Common HEXB polymorphisms reduce serum HexA and HexB enzymatic activities, potentially masking Tay-Sachs disease carrier identification.

Science.gov (United States)

Vallance, Hilary; Morris, Tara J; Coulter-Mackie, Marion; Lim-Steele, Joyce; Kaback, Michael

2006-02-01

A DNA-proven Tay-Sachs disease (TSD) carrier and his brother were found to have serum percent Hexosaminidase A (%HexA) enzymatic activities in the non-carrier range, while the leukocyte %HexA profiles clearly identified them as TSD heterozygotes. Both their serum HexA and HexB enzymatic activities were below reference range, suggesting inheritance of mutations in both the HEXA (alpha-subunit) and HEXB (beta-subunit) genes. DNA sequencing revealed that both individuals, carried the common HEXA 1277_1278insTATC mutation, and two common HEXB polymorphisms: [619A>G (+) delTG]. To determine if these HEXB polymorphisms reduce HexA and HexB enzymatic activities, 69 DNA samples from subjects previously screened enzymatically in both serum and leukocytes for TSD carrier status were selected for either high, mid-range or low serum Total Hex (defined as the sum of HexA and HexB) activities and were tested for the HEXB mutations. Further, three additional TSD carriers ascertained by the atypical pattern of normal serum %HexA but carrier leukocyte %HexA, were found to have the [delTG (+) 619A>G] genotype. In addition, the frequency of the [delTG (+) 619A>G] genotype was significantly higher (P G] haplotype in the Ashkenazi Jewish population (approximately 10%), up to 10% of TSD carriers may have normal serum %HexA values with low total Hex. Accordingly, serum %HexA should not be the sole criterion used for carrier status determination. Where total Hex activity is reduced, further testing with leukocyte Hex profiles is indicated.

Antifungal Activity of Decyl Gallate against Several Species of Pathogenic Fungi

Directory of Open Access Journals (Sweden)

Ana Carolina Alves de Paula e Silva

2014-01-01

Full Text Available This work aims to demonstrate that the gallic acid structure modification to the decyl gallate (G14 compound contributed to increase the antifungal activity against several species of pathogenic fungi, mainly, Candida spp., Cryptococcus spp., Paracoccidioides spp., and Histoplasma capsulatum, according to standardized microdilution method described by Clinical Laboratory Standard Institute (CLSI documents. Moreover this compound has a particularly good selectivity index value, which makes it an excellent candidate for broad-spectrum antifungal prototype and encourages the continuation of subsequent studies for the discovery of its mechanism of action.

Control of a HexaPOD treatment couch for robot-assisted radiotherapy.

Science.gov (United States)

Hermann, Christian; Ma, Lei; Wilbert, Jürgen; Baier, Kurt; Schilling, Klaus

2012-10-01

Moving tumors, for example in the vicinity of the lungs, pose a challenging problem in radiotherapy, as healthy tissue should not be irradiated. Apart from gating approaches, one standard method is to irradiate the complete volume within which a tumor moves plus a safety margin containing a considerable volume of healthy tissue. This work deals with a system for tumor motion compensation using the HexaPOD® robotic treatment couch (Medical Intelligence GmbH, Schwabmünchen, Germany). The HexaPOD, carrying the patient during treatment, is instructed to perform translational movements such that the tumor motion, from the beams-eye view of the linear accelerator, is eliminated. The dynamics of the HexaPOD are characterized by time delays, saturations, and other non-linearities that make the design of control a challenging task. The focus of this work lies on two control methods for the HexaPOD that can be used for reference tracking. The first method uses a model predictive controller based on a model gained through system identification methods, and the second method uses a position control scheme useful for reference tracking. We compared the tracking performance of both methods in various experiments with real hardware using ideal reference trajectories, prerecorded patient trajectories, and human volunteers whose breathing motion was compensated by the system.

Cloning, characterization and targeting of the mouse HEXA gene

Energy Technology Data Exchange (ETDEWEB)

Wakamatsu, N.; Trasler, J.M.; Gravel, R.A. [McGill Univ., Quebec (Canada)] [and others

1994-09-01

The HEXA gene, encoding the {alpha} subunit of {beta}-hexosaminidase A, is essential for the metabolism of ganglioside G{sub M2}, and defects in this gene cause Tay-Sachs disease in humans. To elucidate the role of the gene in the nervous system of the mouse and to establish a mouse model of Tay-Sachs disease, we have cloned and characterized the HEXA gene and targeted a disruption of the gene in mouse ES cells. The mouse HEXA gene spans {approximately}26 kb and consists of 14 exons, similar to the human gene. A heterogeneous transcription initiation site was identified 21-42 bp 5{prime} of the initiator ATG, with two of the sites fitting the consensus CTCA (A = start) as seen for some weak initiator systems. Promoter analysis showed that the first 150 bp 5{prime} of the ATG contained 85% of promoter activity observed in constructs containing up to 1050 bp of 5{prime} sequence. The active region contained a sequence matching that of the adenovirus major late promoter upstream element factor. A survey of mouse tissues showed that the highest mRNA levels were in (max to min): testis (5.5 x brain cortex), adrenal, epididymis, heart, brain, lung, kidney, and liver (0.3 x brain cortex). A 12 kb BstI/SalI fragment containing nine exons was disrupted with the insertion of the bacterial neo{sup r} gene in exon 11 and was targeted into 129/Sv ES cells by homologous recombination. Nine of 153 G418 resistant clones were correctly targeted as confirmed by Southern blotting. The heterozygous ES cells were microinjected into mouse blastocysts and implanted into pseudo-pregnant mice. Nine male chimeric mice, showing that 40-95% chimerism for the 129/Sv agouti coat color marker, are being bred in an effort to generate germline transmission of the disrupted HEXA gene.

BEHAVIOR OF SURFACTANT MIXTURE AT SOLID/LIQUID AND OIL/LIQUID INTERFACE IN CHEMICAL FLOODING SYSTEMS

Energy Technology Data Exchange (ETDEWEB)

Prof. P. Somasundaran

2002-03-01

The aim of the project is to develop and evaluate efficient novel surfactant mixtures for enhanced oil recovery. Preliminary ultra-filtration tests suggest that two kinds of micelles may exist in binary surfactant mixtures at different concentrations. Due to the important role played in interfacial processes by micelles as determined by their structures, focus of the current work is on the delineation of the relationship between such aggregate structures and chemical compositions of the surfactants. A novel analytical centrifuge application is explored to generate information on structures of different surfactants aggregates. In this report, optical systems, typical output of the analytical ultracentrifuge results and four basic experiments are discussed. Initial sedimentation velocity investigations were conducted using nonyl phenol ethoxylated decyl ether (NP-10) to choose the best analytical protocol, calculate the partial specific volume and obtain information on sedimentation coefficient, aggregation mass of micelles. The partial specific volume was calculated to be 0.920. Four softwares: Optima{trademark} XL-A/XL-I data analysis software, DCDT+, Svedberg and SEDFIT, were compared for the analysis of sedimentation velocity experimental data. The sedimentation coefficient and aggregation number of NP-10 micelles obtained using the first three softwares at 25 C are 209, 127, and 111, respectively. The last one is closest to the result from Light Scattering. The reason for the differences in numbers obtained using the three softwares is discussed. Based on these tests, Svedberg and SEDFIT analysis are chosen for further studies. This approach using the analytical ultracentrifugation offers an unprecedented opportunity now to obtain important information on mixed micelles and their role in interfacial processes.

Identification of two HEXA mutations causing infantile-onset Tay-Sachs disease in the Persian population.

Science.gov (United States)

Haghighi, Alireza; Rezazadeh, Jamileh; Shadmehri, Azam Ahmadi; Haghighi, Amirreza; Kornreich, Ruth; Desnick, Robert J

2011-09-01

The β-hexosaminidase A (HEXA) mutations in the first reported cases of infantile Tay-Sachs disease in the Persian population were identified in two unrelated consanguineous families. The clinical diagnoses of the affected infants were confirmed by their markedly deficient levels of HEXA activity in plasma or peripheral leukocytes. The specific causative mutation in each family was determined by sequencing the HEXA alleles in both sets of related parents. Two mutations were identified: c.1A>G (p.MIV), which obliterated the initiating methionine in codon 1, and c.1177C>T (p.R393X), which predicted a termination codon or nonsense mutation.

Performance evaluation of coherent WDM PS-QPSK (HEXA) accounting for non-linear fiber propagation effects.

Science.gov (United States)

Poggiolini, P; Bosco, G; Carena, A; Curri, V; Forghieri, F

2010-05-24

Coherent-detection (CoD) permits to fully exploit the four-dimensional (4D) signal space consisting of the in-phase and quadrature components of the two fiber polarizations. A well-known and successful format exploiting such 4D space is Polarization-multiplexed QPSK (PM-QPSK). Recently, new signal constellations specifically designed and optimized in 4D space have been proposed, among which polarization-switched QPSK (PS-QPSK), consisting of a 8-point constellation at the vertices of a 4D polychoron called hexadecachoron. We call it HEXA because of its geometrical features and to avoid acronym mix-up with PM-QPSK, as well as with other similar acronyms. In this paper we investigate the performance of HEXA in direct comparison with PM-QPSK, addressing non-linear propagation over realistic links made up of 20 spans of either standard single mode fiber (SSMF) or non-zero dispersion-shifted fiber (NZDSF). We show that HEXA not only confirms its theoretical sensitivity advantage over PM-QPSK in back-to-back, but also shows a greater resilience to non-linear effects, allowing for substantially increased span loss margins. As a consequence, HEXA appears as an interesting option for dual-format transceivers capable to switch on-the-fly between PM-QPSK and HEXA when channel propagation degrades. It also appears as a possible direct competitor of PM-QPSK, especially over NZDSF fiber and uncompensated links.

Synthesis and optical properties of new 5'-aryl-substituted 2,5-bis(3-decyl-2,2'-bithiophen-5-yl-1,3,4-oxadiazoles

Directory of Open Access Journals (Sweden)

Anastasia S. Kostyuchenko

2017-02-01

Full Text Available New photoluminescent donor–acceptor–donor (DAD molecules, namely 5'-aryl-substituted 2,5-bis(3-decyl-2,2'-bithiophen-5-yl-1,3,4-oxadiazoles were prepared by palladium-catalyzed coupling from readily available compounds such as ethyl 3-decyl-2,2'-bithiophene-5-carboxylate and aryl halides. The obtained compounds feature increasing bathochromic shifts in their emission spectra with increasing aryl-substituent size yielding blue to bluish-green emissions. At the same time, their absorption spectra are almost independent from the identity of the terminal substituent with λmax values ranging from 395 to 405 nm. The observed trends are perfectly predicted by quantum chemical DFT/TDDFT calculations carried out for these new molecules.

Inositol hexa-phosphate: a potential chelating agent for uranium

International Nuclear Information System (INIS)

Cebrian, D.; Tapia, A.; Real, A.; Morcillo, M.A.

2007-01-01

Chelation therapy is an optimal method to reduce the radionuclide-related risks. In the case of uranium incorporation, the treatment of choice is so far i.v infusion of a 1.4% sodium bicarbonate solution, but the efficacy has been proved to be not very high. In this study, we examine the efficacy of some substances: bicarbonate, citrate, diethylenetriamine pentaacetic acid (DTPA), ethidronate (EHBP) and inositol hexa-phosphate (phytic acid) to chelate uranium using a test developed by Braun et al. Different concentrations of phytic acid, an abundant component of plant seeds that is widely distributed in animal cells and tissues in substantial levels, were tested and compared to the same concentrations of sodium citrate, bicarbonate, EHBP and DTPA. The results showed a strong affinity of inositol hexa-phosphate for uranium, suggesting that it could be an effective chelating agent for uranium in vivo. (authors)

Synthesis and Catalytic Properties of Non-Cross-Linked and Cross-Linked Poly(alkylmethyldiallylammonium bromides) Having Decyl, Octyl, and Hexyl Side Chains

NARCIS (Netherlands)

Wang, G.J; Engberts, J.B.F.N.

1995-01-01

A family of non-cross-linked and cross-linked copolymers containing decyl, octyl, and hexyl groups as side chains ((CL)-CopolC1-10, (CL)-CopolC1-8, and (CL)-CopolC1-6, respectively) were synthesized by radical-initiated cyclocopolymerization of alkylmethyldiallylammonium bromide monomers without and

Transient HEXA expression in a transformed human fetal Tay-Sachs disease neuroglial cell line

Energy Technology Data Exchange (ETDEWEB)

Fernandes, M.J.; Hechtman, P.; Kaplan, F. [McGill Univ., Quebec (Canada)] [and others

1994-09-01

Tay-Sachs disease (TSD) is a severe neurodegenerative disorder characterized by the accumulation of GM{sub 2} ganglioside in the neurons of the central cortex. The recessively inherited disorder results from deficiency of hexosaminidase A (Hex A), a heterodimer of an {alpha} and {beta} subunit encoded by the HEXA and HEXB genes. Expression of HEXA mutations in COS cells has several disadvantages including high endogenous hexosaminidase activity. We report a new transient expression system with very low endogenous Hex A activity. An SV40-transformed fetal TSD neuroglial cell line was assessed for transient expression of the HEXA gene. pCMV{alpha}, a vector incorporating the cytomegalovirus promoter with the human {alpha}-subunit cDNA insert, proved to be the most efficient expression vector. Transfection of 4x10{sup 6} cells with 5-20 {mu}g of plasmid resulted in 100 to 500-fold Hex A activity (4MUGS hydrolysis) relative to mock-transfected cells. Use of pCMV{beta}-Gal as a control for transfection efficiency indicated that 10-20% of cells were transfected. Hex A specific activity increased for at least 72 h post-transfection. This new transient expression system should greatly improve the characterization of mutations in which low levels of HEXA expression result in milder clinical phenotypes and permit studies on enzymatic properties of mutant forms of Hex A. Since the cells used are of CNS origin and synthesize gangliosides, it should also be possible to study, in culture, the metabolic phenotype associated with TSD.

Synthesis, characterization, magnetic and electrochemical properties of a new 3D hexa-copper-substituted germanotungstate

International Nuclear Information System (INIS)

Li, Yanzhou; Luo, Jie; Zhang, Yanting; Zhao, Junwei; Chen, Lijuan; Ma, Pengtao; Niu, Jingyang

2013-01-01

An inorganic–organic hybrid hexa-copper-substituted germanotungstate Na 2 [Cu(dap) 2 ] 2 [Cu(dap) 2 ] ([Cu 6 (H 2 O) 2 (dap) 2 ][B-α-GeW 9 O 34 ] 2 )·4H 2 O (1) (dap=1,2-diaminopropane) has been hydrothermally prepared and characterized by elemental analyses, inductively coupled plasma atomic emission spectrometry (ICP–AES) analyses, IR spectra, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) and single-crystal X-ray diffraction. 1 displays the six-connected 3D network with the long topological (O′Keefe) vertex symbol is 4·4·6 4 ·4·4·4·4·6 4 ·4·4·4·6 4 ·4·4·4 and the short vertex (Schläfli) symbol of 4 12 6 3 . Magnetic measurements indicate that there are the overall ferromagnetic exchange interactions in the belt-like hexa-Cu II cluster in 1. Furthermore, the electrochemical behavior and electrocatalysis of 1 modified carbon paste electrode (1-CPE) have been studied. The reductions of nitrite, bromate and hydrogen peroxide are principally mediated by the W VI -based wave. - Graphical abstract: A hexa-Cu II sandwiched germanotungstate has been synthesized and structurally characterized. The magnetic, solid-state electrochemical and electrocatalytic properties have been investigated. Display Omitted - Highlights: • Transition-metal substituted polyoxometalates. • Hexa-copper-substituted germanotungstate. • Six-connected 3D network. • Electrocatalytic reduction of nitrite, bromate and hydrogen peroxide

Confinement of a nonionic surfactant membrane within a montmorillonite as a new way to prepare organoclay materials

Energy Technology Data Exchange (ETDEWEB)

Guegan, Regis, E-mail: regis.guegan@univ-orleans.fr [Universite d' Orleans (France); Giovanela, Marcelo [Universidade de Caxias do Sul (UCS), RS (Brazil)

2016-11-15

The aim of this study was to prepare and characterize a hybrid layered material (organoclay) with a Na-montmorillonite and the triethylene glycol mono-n-decyl ether (C{sub 10}E{sub 3} ) nonionic surfactant which forms a lamellar phase at room temperature. The synthesized organoclay was characterized by complementary techniques (Fourier transform infrared spectroscopy and X-ray diffraction). Experiments in conjunction with electron density analysis showed that a bilayer or membrane of C{sub 10}E{sub 3} was intercalated within the interlayer space of a naturally exchanged Na-montmorillonite. The intercalation of a bilayer of C{sub 10}E{sub 3} in a clay mineral offers new perspectives for the manufacturing of nanomaterials. While showing a hydrophobic surface and a large interlayer space value, the resulting organoclay preserves the compensating cations within the interlayer space allowing one to perform ion exchanges, making easier the intercalation of further organic molecules of important size with functional properties or for environmental purposes. (author)

Synergistic extraction of actinides : Part I. Hexa-and pentavalent actinides

International Nuclear Information System (INIS)

Patil, S.K.; Ramakrishna, V.V.

1980-01-01

A detailed discussion on the reported literature on the synergistic extraction of hexa- and pentavalent actinide ions, by different combinations of extractants and from different aqueous media, is presented. Structural aspects of the various complexes involved in synergism also are reviewed. A short account of the applications based on synergistic extraction is also given. (author)

Synthesis, characterization, magnetic and electrochemical properties of a new 3D hexa-copper-substituted germanotungstate

Energy Technology Data Exchange (ETDEWEB)

Li, Yanzhou; Luo, Jie; Zhang, Yanting [Institute of Molecular and Crystal Engineering, Henan Key Lab of Polyoxometalate Chemistry, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); Zhao, Junwei, E-mail: zhaojunwei@henu.edu.cn [Institute of Molecular and Crystal Engineering, Henan Key Lab of Polyoxometalate Chemistry, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); Basic Experiment Teaching Center, Henan University, Kaifeng, Henan 475004 (China); Chen, Lijuan, E-mail: ljchen@henu.edu.cn [Institute of Molecular and Crystal Engineering, Henan Key Lab of Polyoxometalate Chemistry, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Ma, Pengtao; Niu, Jingyang [Institute of Molecular and Crystal Engineering, Henan Key Lab of Polyoxometalate Chemistry, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China)

2013-09-15

An inorganic–organic hybrid hexa-copper-substituted germanotungstate Na{sub 2}[Cu(dap){sub 2}]{sub 2}[Cu(dap){sub 2}] ([Cu{sub 6}(H{sub 2}O){sub 2}(dap){sub 2}][B-α-GeW{sub 9}O{sub 34}]{sub 2})·4H{sub 2}O (1) (dap=1,2-diaminopropane) has been hydrothermally prepared and characterized by elemental analyses, inductively coupled plasma atomic emission spectrometry (ICP–AES) analyses, IR spectra, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) and single-crystal X-ray diffraction. 1 displays the six-connected 3D network with the long topological (O′Keefe) vertex symbol is 4·4·6{sub 4}·4·4·4·4·6{sub 4}·4·4·4·6{sub 4}·4·4·4 and the short vertex (Schläfli) symbol of 4{sup 12}6{sup 3}. Magnetic measurements indicate that there are the overall ferromagnetic exchange interactions in the belt-like hexa-Cu{sup II} cluster in 1. Furthermore, the electrochemical behavior and electrocatalysis of 1 modified carbon paste electrode (1-CPE) have been studied. The reductions of nitrite, bromate and hydrogen peroxide are principally mediated by the W{sup VI}-based wave. - Graphical abstract: A hexa-Cu{sup II} sandwiched germanotungstate has been synthesized and structurally characterized. The magnetic, solid-state electrochemical and electrocatalytic properties have been investigated. Display Omitted - Highlights: • Transition-metal substituted polyoxometalates. • Hexa-copper-substituted germanotungstate. • Six-connected 3D network. • Electrocatalytic reduction of nitrite, bromate and hydrogen peroxide.

Synthesis,thermal property and hydrolytic degradation of a novel star-shaped hexa[p-(carbonylglycinomethylester)phenoxy]cyclotriphosphazene

Institute of Scientific and Technical Information of China (English)

无

2009-01-01

A novel star-shaped cyclotriphosphazene substituted by glycinomethylesterphenoxy and its intermediates are synthesized from hexachlorocyclotriphosphazene (HCCP). The structures are characterized by 1H NMR,13C NMR,31P NMR,FTIR and elemental analysis. Their thermal properties are clarified by thermogravimetric analysis (TGA),differential scanning calorimentry (DSC) and FTIR,while hydrolytic degradation behaviour is studied with UV-vis spectrophotometer and by measuring the weight loss,and the phosphorus content of residue. According to hydrolysis behaviour of hexa[p-(carbonylglycinomethylester)phenoxy]cyclotriphosphazene (HGPCP) under different conditions,it is easy to hydrolyze in hydrochloric acid (pH 1.0) than in phosphate buffer (pH 7.4) at 37℃. And the sample hydrolytic degradation still remains at the stage of side groups’ break. The TGA data show that the thermal stability of the hexa[p-(aldehyde)phenoxy]cyclotriphosphazene (HAPCP),hexa[p-(carboxyl) phenoxy]cyclotriphosphazene (HCPCP) and HGPCP is so high that their char residues are 75%,47% and 47% at 800℃,respectively,probably due to cross-linking between molecules.

Measurements of temperature of the tungsten hexa-ethoxide pyrolysis flame using IR camera

CSIR Research Space (South Africa)

Mudau, AE

2010-09-01

Full Text Available In laser pyrolysis, temperature measurement and control plays a vital role during the development of nanoparticles. Authors present the results of temperature measurements using infrared camera on a tungsten hexa-ethoxide pyrolysis flame used...

Tay–Sachs disease mutations in HEXA target the α chain of hexosaminidase A to endoplasmic reticulum–associated degradation

Science.gov (United States)

Dersh, Devin; Iwamoto, Yuichiro; Argon, Yair

2016-01-01

Loss of function of the enzyme β-hexosaminidase A (HexA) causes the lysosomal storage disorder Tay–Sachs disease (TSD). It has been proposed that mutations in the α chain of HexA can impair folding, enzyme assembly, and/or trafficking, yet there is surprisingly little known about the mechanisms of these potential routes of pathogenesis. We therefore investigated the biosynthesis and trafficking of TSD-associated HexA α mutants, seeking to identify relevant cellular quality control mechanisms. The α mutants E482K and G269S are defective in enzymatic activity, unprocessed by lysosomal proteases, and exhibit altered folding pathways compared with wild-type α. E482K is more severely misfolded than G269S, as observed by its aggregation and inability to associate with the HexA β chain. Importantly, both mutants are retrotranslocated from the endoplasmic reticulum (ER) to the cytosol and are degraded by the proteasome, indicating that they are cleared via ER-associated degradation (ERAD). Leveraging these discoveries, we observed that manipulating the cellular folding environment or ERAD pathways can alter the kinetics of mutant α degradation. Additionally, growth of patient fibroblasts at a permissive temperature or with chemical chaperones increases cellular Hex activity by improving mutant α folding. Therefore modulation of the ER quality control systems may be a potential therapeutic route for improving some forms of TSD. PMID:27682588

Rapid identification of HEXA mutations in Tay-Sachs patients.

Science.gov (United States)

Giraud, Carole; Dussau, Jeanne; Azouguene, Emilie; Feillet, François; Puech, Jean-Philippe; Caillaud, Catherine

2010-02-19

Tay-Sachs disease (TSD) is a recessively inherited neurodegenerative disorder due to mutations in the HEXA gene resulting in a beta-hexosaminidase A (Hex A) deficiency. The purpose of this study was to characterize the molecular abnormalities in patients with infantile or later-onset forms of the disease. The complete sequencing of the 14 exons and flanking regions of the HEXA gene was performed with a unique technical condition in 10 unrelated TSD patients. Eleven mutations were identified, including five splice mutations, one insertion, two deletions and three single-base substitutions. Four mutations were novel: two splice mutations (IVS8+5G>A, IVS2+4delAGTA), one missense mutation in exon 6 (c.621T>G (p.D207E)) and one small deletion (c.1211-1212delTG) in exon 11 resulting in a premature stop codon at residue 429. The c.621T>G missense mutation was found in a patient presenting an infantile form. Its putative role in the pathogenesis of TSD is suspected as residue 207 is highly conserved in human, mouse and rat. Moreover, structural modelling predicted changes likely to affect substrate binding and catalytic activity of the enzyme. The time-saving procedure reported here could be useful for the characterization of Tay-Sachs-causing mutations, in particular in non-Ashkenazi patients mainly exhibiting rare mutations. Copyright (c) 2010 Elsevier Inc. All rights reserved.

Methods of use of calcium hexa aluminate refractory linings and/or chemical barriers in high alkali or alkaline environments

Science.gov (United States)

McGowan, Kenneth A; Cullen, Robert M; Keiser, James R; Hemrick, James G; Meisner, Roberta A

2013-10-22

A method for improving the insulating character/and or penetration resistance of a liner in contact with at least one of an alkali and/or alkaline environments is provided. The method comprises lining a surface that is subject to wear by an alkali environment and/or an alkaline environment with a refractory composition comprising a refractory aggregate consisting essentially of a calcium hexa aluminate clinker having the formula CA.sub.6, wherein C is equal to calcium oxide, wherein A is equal to aluminum oxide, and wherein the hexa aluminate clinker has from zero to less than about fifty weight percent C.sub.12A.sub.7, and wherein greater than 98 weight percent of the calcium hexa aluminate clinker having a particle size ranging from -20 microns to +3 millimeters, for forming a liner of the surface. This method improves the insulating character/and or penetration resistance of the liner.

Improving accuracy of Tay Sachs carrier screening of the non-Jewish population: analysis of 34 carriers and six late-onset patients with HEXA enzyme and DNA sequence analysis.

Science.gov (United States)

Park, Noh Jin; Morgan, Craig; Sharma, Rajesh; Li, Yuanyin; Lobo, Raynah M; Redman, Joy B; Salazar, Denise; Sun, Weimin; Neidich, Julie A; Strom, Charles M

2010-02-01

The purpose of this study was to determine whether combining different testing modalities namely beta-hexosaminidase A (HEXA) enzyme analysis, HEXA DNA common mutation assay, and HEXA gene sequencing could improve the sensitivity for carrier detection in non-Ashkenazi (AJ) individuals. We performed a HEXA gene sequencing assay, a HEXA DNA common mutation assay, and a HEXA enzyme assay on 34 self-reported Tay-Sachs disease (TSD) carriers, six late-onset patients with TSD, and one pseudodeficiency allele carrier. Sensitivity of TSD carrier detection was 91% for gene sequencing compared with 91% for the enzyme assay and 52% for the DNA mutation assay. Gene sequencing combined with enzyme testing had the highest sensitivity (100%) for carrier detection. Gene sequencing detected four novel mutations, three of which are predicted to be disease causing [118.delT, 965A-->T (D322V), and 775A-->G (T259A)]. Gene sequencing is useful in identifying rare mutations in patients with TSD and their families, in evaluating spouses of known carriers for TSD who have indeterminate enzyme analysis and negative for common mutation analysis, and in resolving ambiguous enzyme testing results.

GM2 gangliosidoses in Spain: analysis of the HEXA and HEXB genes in 34 Tay-Sachs and 14 Sandhoff patients.

Science.gov (United States)

Gort, Laura; de Olano, Natalia; Macías-Vidal, Judit; Coll, M A Josep

2012-09-10

The GM2 gangliosidoses are autosomal recessive lysosomal storage diseases caused by a deficiency of the β-hexosaminidase A enzyme. This enzyme is composed of two polypeptide chains designated the α- and β- subunits and it interacts with the GM2 activator protein. The HEXA and HEXB genes encode the α-subunit and the β-subunit, respectively. Mutations in these genes are causative of Tay-Sachs disease (HEXA) and Sandhoff disease (HEXB). We analyzed the complete HEXA gene in 34 Spanish patients with Tay-Sachs disease and the HEXB gene in 14 Spanish patients with Sandhoff disease. We identified 27 different mutations, 14 of which were novel, in the HEXA gene and 14 different mutations, 8 of which unreported until now, in the HEXB gene, and we attempted to correlate these mutations with the clinical presentation of the patients. We found a high frequency of c.459+5G>A (IVS4+5G>A) mutation in HEXA affected patients, 22 of 68 alleles, which represent the 32.4%. This is the highest percentage found of this mutation in a population. All patients homozygous for mutation c.459+5G>A presented with the infantile form of the disease and, as previously reported, patients carrying mutation p.R178H in at least one of the alleles presented with a milder form. In HEXB affected patients, the novel deletion c.171delG accounts for 21.4% of the mutant alleles (6/28). All patients with this deletion showed the infantile form of the disease. The Spanish GM2 gangliosidoses affected patients show a great mutational heterogeneity as seen in other inherited lisosomal diseases in this country. Copyright © 2012. Published by Elsevier B.V.

GM2 gangliosidosis associated with a HEXA missense mutation in Japanese Chin dogs: a potential model for Tay Sachs disease.

Science.gov (United States)

Sanders, Douglas N; Zeng, Rong; Wenger, David A; Johnson, Gary S; Johnson, Gayle C; Decker, Jared E; Katz, Martin L; Platt, Simon R; O'Brien, Dennis P

2013-01-01

GM2 gangliosidosis is a fatal lysosomal storage disease caused by a deficiency of β-hexosaminidase (EC 3.2.1.52). There are two major isoforms of the enzyme: hexosaminidase A composed of an α and a β subunit (encoded by HEXA and HEXB genes, respectively); and, hexosaminidase B composed of two β subunits. Hexosaminidase A requires an activator protein encoded by GM2A to catabolize GM2 ganglioside, but even in the absence of the activator protein, it can hydrolyze the synthetic substrates commonly used to assess enzyme activity. GM2 gangliosidosis has been reported in Japanese Chin dogs, and we identified the disease in two related Japanese Chin dogs based on clinical signs, histopathology and elevated brain GM2 gangliosides. As in previous reports, we found normal or elevated hexosaminidase activity when measured with the synthetic substrates. This suggested that the canine disease is analogous to human AB variant of G(M2) gangliosidosis, which results from mutations in GM2A. However, only common neutral single nucleotide polymorphisms were found upon sequence analysis of the canine ortholog of GM2A from the affected Japanese Chins. When the same DNA samples were used to sequence HEXA, we identified a homozygous HEXA:c967G>A transition which predicts a p.E323K substitution. The glutamyl moiety at 323 is known to make an essential contribution to the active site of hexosaminidase A, and none of the 128 normal Japanese Chins and 92 normal dogs of other breeds that we tested was homozygous for HEXA:c967A. Thus it appears that the HEXA:c967G>A transition is responsible for the GM2 gangliosidosis in Japanese Chins. Copyright © 2012 Elsevier Inc. All rights reserved.

Fluorescence spectroscopic study of the aggregation behavior of non-cross-linked and cross-linked poly(alkylmethyldiallylammonium bromides) having decyl, octyl, and hexyl side chains in aqueous solution

NARCIS (Netherlands)

Wang, G.J; Engberts, J.B.F.N.

1996-01-01

The conformational state of a series of non-cross-linked and cross-linked poly(alkylmethyldiallylammonium bromides) bearing decyl, octyl, and hexyl side chains ((CL)-CopolC1-10, (CL)-CopolC1-8, and (CL)-CopolC1-6, respectively) in aqueous solutions were investigated by fluorescence spectroscopy

Tay-Sachs disease mutations in HEXA target the α chain of hexosaminidase A to endoplasmic reticulum-associated degradation.

Science.gov (United States)

Dersh, Devin; Iwamoto, Yuichiro; Argon, Yair

2016-12-01

Loss of function of the enzyme β-hexosaminidase A (HexA) causes the lysosomal storage disorder Tay-Sachs disease (TSD). It has been proposed that mutations in the α chain of HexA can impair folding, enzyme assembly, and/or trafficking, yet there is surprisingly little known about the mechanisms of these potential routes of pathogenesis. We therefore investigated the biosynthesis and trafficking of TSD-associated HexA α mutants, seeking to identify relevant cellular quality control mechanisms. The α mutants E482K and G269S are defective in enzymatic activity, unprocessed by lysosomal proteases, and exhibit altered folding pathways compared with wild-type α. E482K is more severely misfolded than G269S, as observed by its aggregation and inability to associate with the HexA β chain. Importantly, both mutants are retrotranslocated from the endoplasmic reticulum (ER) to the cytosol and are degraded by the proteasome, indicating that they are cleared via ER-associated degradation (ERAD). Leveraging these discoveries, we observed that manipulating the cellular folding environment or ERAD pathways can alter the kinetics of mutant α degradation. Additionally, growth of patient fibroblasts at a permissive temperature or with chemical chaperones increases cellular Hex activity by improving mutant α folding. Therefore modulation of the ER quality control systems may be a potential therapeutic route for improving some forms of TSD. © 2016 Dersh et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Efficient and accurate stereotactic radiotherapy using flattening filter free beams and HexaPOD robotic tables

DEFF Research Database (Denmark)

Nielsen, Morten; Hansen, C. R.; Brink, C.

2016-01-01

Flattening filter free (FFF) high dose rate beam technique was introduced for brain stereotactic radiosurgery (SRS) and lung Stereotactic Body Radiotherapy (SBRT). Furthermore, a HexaPOD treatment table was introduced for the brain SRS to enable correction of rotational setup errors. 19 filter fl...

HexaMob—A Hybrid Modular Robotic Design for Implementing Biomimetic Structures

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Sasanka Sankhar Reddy CH.

2017-10-01

Full Text Available Modular robots are capable of forming primitive shapes such as lattice and chain structures with the additional flexibility of distributed sensing. The biomimetic structures developed using such modular units provides ease of replacement and reconfiguration in co-ordinated structures, transportation etc. in real life scenarios. Though the research in the employment of modular robotic units in formation of biological organisms is in the nascent stage, modular robotic units are already capable of forming such sophisticated structures. The modular robotic designs proposed so far in modular robotics research vary significantly in external structures, sensor-actuator mechanisms interfaces for docking and undocking, techniques for providing mobility, coordinated structures, locomotions etc. and each robotic design attempted to address various challenges faced in the domain of modular robotics by employing different strategies. This paper presents a novel modular wheeled robotic design - HexaMob facilitating four degrees of freedom (2 degrees for mobility and 2 degrees for structural reconfiguration on a single module with minimal usage of sensor-actuator assemblies. The crucial features of modular robotics such as back-driving restriction, docking, and navigation are addressed in the process of HexaMob design. The proposed docking mechanism is enabled using vision sensor, enhancing the capabilities in docking as well as navigation in co-ordinated structures such as humanoid robots.

Surfactant phosphatidylcholine metabolism and surfactant function in preterm, ventilated lambs

International Nuclear Information System (INIS)

Jobe, A.H.; Ikegami, M.; Seidner, S.R.; Pettenazzo, A.; Ruffini, L.

1989-01-01

Preterm lambs were delivered at 138 days gestational age and ventilated for periods up to 24 h in order to study surfactant metabolism and surfactant function. The surfactant-saturated phosphatidylcholine pool in the alveolar wash was 13 +/- 4 mumol/kg and did not change from 10 min to 24 h after birth. Trace amounts of labeled natural sheep surfactant were mixed with fetal lung fluid at birth. By 24 h, 80% of the label had become lung-tissue-associated, yet there was no loss of label from phosphatidylcholine in the lungs when calculated as the sum of the lung tissue plus alveolar wash. De novo synthesized phosphatidylcholine was labeled with choline given by intravascular injection at 1 h of age. Labeled phosphatidylcholine accumulated in the lung tissue linearly to 24 h, and the labeled phosphatidylcholine moved through lamellar body to alveolar pools. The turnover time for alveolar phosphatidylcholine was estimated to be about 13 h, indicating an active metabolic pool. A less surface-active surfactant fraction recovered as a supernatant after centrifugation of the alveolar washes at 40,000 x g increased from birth to 10 min of ventilation, but no subsequent changes in the distribution of surfactant phosphatidylcholine in surfactant fractions occurred. The results were consistent with recycling pathway(s) that maintained surface-active surfactant pools in preterm ventilated lambs

Persurf, a new method to improve surfactant delivery: a study in surfactant depleted rats.

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Wolfram Burkhardt

Full Text Available PURPOSE: Exogenous surfactant is not very effective in adults with ARDS, since surfactant does not reach atelectatic alveoli. Perfluorocarbons (PFC can recruit atelectatic areas but do not replace impaired endogenous surfactant. A surfactant-PFC-mixture could combine benefits of both therapies. The aim of the proof-of-principal-study was to produce a PFC-in-surfactant emulsion (Persurf and to test in surfactant depleted Wistar rats whether Persurf achieves I. a more homogenous pulmonary distribution and II. a more homogenous recruitment of alveoli when compared with surfactant or PFC alone. METHODS: Three different PFC were mixed with surfactant and phospholipid concentration in the emulsion was measured. After surfactant depletion, animals either received 30 ml/kg of PF5080, 100 mg/kg of stained (green dye Curosurf™ or 30 ml/kg of Persurf. Lungs were fixated after 1 hour of ventilation and alveolar aeration and surfactant distribution was estimated by a stereological approach. RESULTS: Persurf contained 3 mg/ml phospholipids and was stable for more than 48 hours. Persurf-administration improved oxygenation. Histological evaluation revealed a more homogenous surfactant distribution and alveolar inflation when compared with surfactant treated animals. CONCLUSIONS: In surfactant depleted rats administration of PFC-in-surfactant emulsion leads to a more homogenous distribution and aeration of the lung than surfactant alone.

Phase equilibria of microemulsion forming system n-decyl-(beta)-D-glucopyranoside/water/n-octane/1-butanol

DEFF Research Database (Denmark)

Kahl, Heike; Quitzsch, Konrad; Stenby, Erling Halfdan

1997-01-01

of multicomponent system is the coexistence of a highly structural liquid phase enriched with amphiphilic compounds and an excess water or an excess oil phase or both of them. The phase behaviour was studied experimentally by use of turbidity titration and HPLC measurements and theoretically by application...... of the UNIQUAC-equation and the UNIFAC-method. The UNIFAC-method is able to describe the phase behaviour in the quaternary system qualitatively, without fitting parameters. However, by applying the UNIQUAC-method, with adjustable parameters, it was only possible to model the ternary subsystems. The modelling......A systematic investigation of the phase behaviour involving microemulsions is presented with respect to experimental and calculated data for the four-component system n-decyl-(beta)-D-glucopyranoside/water/n-octane/1-butanol and its corresponding ternaries at 25°C. The main feature of this kind...

Local Structure in Americium and Californium Hexa-cyanoferrates - Comparison with Their Lanthanide Analogues

International Nuclear Information System (INIS)

Dupouy, G.; Bonhoure, I.; Dumas, Th.; Moisy, Ph.; Petit, S.; Den Auwer, Ch.; Conradson, St.D.; Hennig, Ch.; Scheinost, A.C.; Le Naour, C.; Simoni, E.

2011-01-01

Metal hexa-cyanoferrates are well known molecular solids for a large variety of cations, although very little has been described for actinide adducts. Two new members of actinide(III) hexa-cyanoferrates were synthesized with the cations americium and californium. They were structurally characterized by infrared and X-ray absorption spectroscopy. Combined EXAFS data at the iron K edge and actinide L 3 edge provide evidence for a three-dimensional model for these two new compounds. Structural data in terms of bond lengths were compared to those reported for the parent lanthanide(III) compounds, neodymium and gadolinium hexa-cyanoferrates, respectively: the americium compound with (KNd(III)Fe(II)-Fe-III(CN) 6 .4H 2 O and the californium compound with (KGd(III)Fe(II)(CN) . 3.5H 2 O and (KGd(III)Fe(II)(CN) 6 .3H 2 O. This comparison between actinide and lanthanide homologues has been carried out on the basis of ionic radii considerations. The americium and neodymium environments appear to be very similar and are arranged in a tri-capped trigonal prism polyhedron of coordination number 9 (CN: 9), in which the americium atom is bonded to six nitrogen atoms and to three water molecules. For the californium adduct, a similar comparison and bond length and angle values derived from EXAFS studies suggest that the californium cation sits in a bi-capped trigonal prism (CN: 8) as in (KGd(III)Fe(II)(CN) 6 . 3H 2 O. This arrangement differs from that in the structure of (KGd(III)Fe(II)(CN) 6 .3.5H 2 O, in which the gadolinium atom is surrounded by 9 atoms. This is one of the rare pieces of information revealed by EXAFS spectroscopy for americium and californium in comparison to lanthanide atoms in molecular solid compounds. A discussion on the decrease in bond length and coordination number from americium to californium is also provided, on the basis of crystallographic results reported in the literature for actinide(III) and lanthanide(III) hydrate series. (authors)

Pulmonary surfactant and lung transplantation

NARCIS (Netherlands)

Erasmus, Michiel Elardus

1997-01-01

Pulmonary surfactant lowers the surface tension at the air-water interface inside the alveolus. This is achieved by adsorption of surfactant phospholipids at the air-water interface, a process controlled by surfactant-associated proteins, such as SP-A. In this way, surfactant prevents collapse of

Microemulsion-based lycopene extraction: Effect of surfactants, co-surfactants and pretreatments.

Science.gov (United States)

Amiri-Rigi, Atefeh; Abbasi, Soleiman

2016-04-15

Lycopene is a potent antioxidant that has received extensive attention recently. Due to the challenges encountered with current methods of lycopene extraction using hazardous solvents, industry calls for a greener, safer and more efficient process. The main purpose of present study was application of microemulsion technique to extract lycopene from tomato pomace. In this respect, the effect of eight different surfactants, four different co-surfactants, and ultrasound and enzyme pretreatments on lycopene extraction efficiency was examined. Experimental results revealed that application of combined ultrasound and enzyme pretreatments, saponin as a natural surfactant, and glycerol as a co-surfactant, in the bicontinuous region of microemulsion was the optimal experimental conditions resulting in a microemulsion containing 409.68±0.68 μg/glycopene. The high lycopene concentration achieved, indicates that microemulsion technique, using a low-cost natural surfactant could be promising for a simple and safe separation of lycopene from tomato pomace and possibly from tomato industrial wastes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Structural and magnetic Properties of TbZn-substituted calcium barium M-type nano-structured hexa-ferrites

Energy Technology Data Exchange (ETDEWEB)

Khan, Hasan M. [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Department of Electronics, University of York, York YO10 5DD (United Kingdom); Islam, M.U., E-mail: dr.misbahulislam@bzu.edu.pk [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Xu, Yongbing [Department of Electronics, University of York, York YO10 5DD (United Kingdom); Nanjing–York International Centre of Spintronics and Nano-Engineering, Nanjing University, Nanjing 210093 (China); Asif Iqbal, M. [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); National University of Science and Technology, College of E and ME, Islamabad (Pakistan); Ali, Irshad [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan)

2014-03-15

Highlights: • Tb–Zn substituted Ca{sub 0.5}Ba{sub 0.5}Fe{sub 12}O{sub 19} samples exhibit single magnetoplumbite phase. • Lattice parameters a and c have increasing values. • Coercivity can be tuned at lower substitution level • Crystallites size was found in the range 18–25 nm by TEM and by Scherrer formula. • These hexa-ferrites are suitable for microwave devices and magnetic recording media. -- Abstract: Effect of TbZn substitution on the structural and magnetic properties of Ca{sub 0.5}Ba{sub 0.5−x}Tb{sub x}Zn{sub y}Fe{sub 12−y}O{sub 19}, (x = 0.00–0.10; y = 0.00–1.00) ferrites prepared by sol–gel auto combustion is reported. The synthesized samples were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Vibrating Sample magnetometery. The X-ray diffraction analysis confirmed single phase M-type hexa-ferrite structure. The lattice parameters were found to increase as TbZn contents increases, which is attributed to the ionic sizes of the implicated cations. The TbZn seems to be completely soluble in the lattice. The results of scanning electron microscopy and transmission electron microscopy shows that the grain size decreases with increase of TbZn substitution. The coercivity values (1277–2025 Oe) of all samples lies in the range of M-type hexa-ferrite and indicate that an increase of anisotropy was achieved by substitution of TbZn, while the size of nanoparticles was drastically reduced between 18 and 25 nm. The increased anisotropy and fine particle size are useful for many applications, such as improving signal noise ratio of recording devices.

Structure and Conformational Dynamics of DMPC/Dicationic Surfactant and DMPC/Dicationic Surfactant/DNA Systems

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Maciej Kozak

2013-04-01

Full Text Available Amphiphilic dicationic surfactants, known as gemini surfactants, are currently studied for gene delivery purposes. The gemini surfactant molecule is composed of two hydrophilic “head” groups attached to hydrophobic chains and connected via molecular linker between them. The influence of different concentrations of 1,5-bis (1-imidazolilo-3-decyloxymethyl pentane chloride (gemini surfactant on the thermotropic phase behaviour of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC bilayers with and without the presence of DNA was investigated using Fourier transformed infrared (FTIR and circular dichroism (CD spectroscopies, small angle scattering of synchrotron radiation and differential scanning calorimetry. With increasing concentration of surfactant in DMPC/DNA systems, a disappearance of pretransition and a decrease in the main phase transition enthalpy and temperature were observed. The increasing intensity of diffraction peaks as a function of surfactant concentration also clearly shows the ability of the surfactant to promote the organisation of lipid bilayers in the multilayer lamellar phase.

Surfactant Membrane Phases Containing Mixtures of Hydrocarbon and Fluorocarbon Surfactants

International Nuclear Information System (INIS)

de Campo, Liliana; Warr, G.G.

2005-01-01

Full text: We describe the structure and stability of sponge and lamellar phases comprising mixtures of hydrocarbon and fluorocarbon surfactants. Such mixtures can show limited miscibility with each other, forming for example coexisting populations of hydrocarbon rich and fluorocarbon rich micelles under some circumstances. Our system is based on the well-characterised lamellar and sponge phases of cetylpyridinium chloride, hexanol and 0.2M brine, into which the partially fluorinated surfactant N-1H,1H,2H,2H-tridecafluorooctylpyridinium chloride is incorporated. By probing the structures with SAXS (small angle x-ray scattering) and SANS (small angle neutron scattering) using contrast variation, and by characterizing the dynamic properties with dynamic light scattering, we will describe the effect of incorporating the fluorinated surfactant on the phase equilibria and properties of the surfactant membrane structures. (authors)

Surfactant-Mediated Growth Revisited

International Nuclear Information System (INIS)

Meyerheim, H. L.; Sander, D.; Popescu, R.; Pan, W.; Kirschner, J.; Popa, I.

2007-01-01

The x-ray structure analysis of the oxygen-surfactant-mediated growth of Ni on Cu(001) identifies up to 0.15 monolayers of oxygen in subsurface octahedral sites. This questions the validity of the general view that surfactant oxygen floats on top of the growing Ni film. Rather, the surfactant action is ascribed to an oxygen-enriched zone extending over the two topmost layers. Surface stress measurements support this finding. Our results have important implications for the microscopic understanding of surfactant-mediated growth and the change of the magnetic anisotropy of the Ni films

Surfactants in tribology

CERN Document Server

Biresaw, Girma

2014-01-01

Surface science and tribology play very critical roles in many industries. Manufacture and use of almost all consumer and industrial products rely on the application of advanced surface and tribological knowledge. The fourth in a series, Surfactants in Tribology, Volume 4 provides an update on research and development activities connecting surfactants and tribological phenomena. Written by renowned subject matter experts, the book demonstrates how improved design of surfactants can be harnessed to control tribological phenomena. Profusely illustrated and copiously referenced, the chapters also

Ion-specific weak adsorption of salts and water/octanol transfer free energy of a model amphiphilic hexa-peptide

International Nuclear Information System (INIS)

Dejugnat, Ch.; Dufreche, J.F.; Zemb, Th.; Dejugnat, Ch.

2011-01-01

An amphiphilic hexa-peptide has been used as a model to quantify how specific ion effects induced by addition of four salts tune the hydrophilic/hydrophobic balance and induce temperature-dependant coacervate formation from aqueous solution. The hexa-peptide chosen is present as a dimer with low transfer energy from water to octanol. Taking sodium chloride as the reference state in the Hofmeister scale, we identify water activity effects and therefore measure the free energy of transfer from water to octanol and separately the free energy associated to the adsorption of chaotropic ions or the desorption of kosmotropic ions for the same amphiphilic peptide. These effects have the same order of magnitude: therefore, both energies of solvation as well as transfer into octanol strongly depend on the nature of the electrolytes used to formulate any buffer. Model peptides could be used on separation processes based on criteria linked to 'Hofmeister' but different from volume and valency. (authors)

Surfactant replacement therapy--economic impact.

Science.gov (United States)

Pejaver, R K; al Hifzi, I; Aldussari, S

2001-06-01

Surfactant replacement is an effective treatment for neonatal respiratory distress syndrome. (RDS). As widespread use of surfactant is becoming a reality, it is important to assess the economic implications of this new form of therapy. A comparison study was carried out at the Neonatal Intensive Care Unit (NICU) of Northwest Armed Forces Hospital, Saudi Arabia. Among 75 infants who received surfactant for RDS and similar number who were managed during time period just before the surfactant was available, but by set criteria would have made them eligible for surfactant. All other management modalities except surfactant were the same for all these babies. Based on the intensity of monitoring and nursing care required by the baby, the level of care was divided as: Level IIIA, IIIB, Level II, Level I. The cost per day per bed for each level was calculated, taking into account the use of hospital immovable equipment, personal salaries of nursing, medical, ancillary staff, overheads and maintenance, depreciation and replacement costs. Medications used, procedures done, TPN, oxygen, were all added to individual patient's total expenditure. 75 infants in the Surfactant group had 62 survivors. They spent a total of 4300 days in hospital. (av 69.35) Out of which 970 d (av 15.65 per patient) were ventilated days. There were 56 survivors in the non-surfactant group of 75. They had spent a total of 5023 days in the hospital (av 89.69/patient) out of which 1490 were ventilated days (av 26.60 d). Including the cost of surfactant (two doses), cost of hospital stay for each infant taking the average figures of stay would be SR 118, 009.75 per surfactant treated baby and SR 164, 070.70 per non-surfactant treated baby. The difference of 46,061 SR is 39.03% more in non-surfactant group. One Saudi rial = 8 Rs (approx at the time study was carried out.) Medical care cost varies from place to place. However, it is definitely cost-effective where surfactant is concerned. Quality adjusted

Physical stability, centrifugation tests, and entrapment efficiency studies of carnauba wax-decyl oleate nanoparticles used for the dispersion of inorganic sunscreens in aqueous media.

Science.gov (United States)

Villalobos-Hernández, J R; Müller-Goymann, C C

2006-06-01

Aqueous nanoscale lipid dispersions consisting of carnauba wax-decyl oleate mixtures acting as carriers or accompanying vehicles for inorganic sunscreens such as barium sulfate, strontium carbonate, and titanium dioxide were prepared by high pressure homogenization. For the manufacture of these nanosuspensions, three pigment concentrations (%wt), namely 2, 4, and 6, and two carnauba wax-decyl oleate ratios, 1:1 and 2:1, were used, being some of these combinations chosen for stability studies. Six-month physical stability tests at 4, 20, and 40 degrees C selecting the mean particle size and the polydispersity index of the nanosuspensions as reference parameters were performed. Centrifugation tests of the nanosuspensions assessed by transmission electron microscopy and by the determination of the content of pigments and carnauba wax in the separated fractions were done. The mean particle sizes and the polydispersity indices of the nanosuspensions were not altered after six-month storages at 20 and at 40 degrees C. However, the storage of those at 4 degrees C considerably increased the particle size and polydispersity of the systems, particularly when wax-oil ratios (2:1) were used for the entrapment of the pigments. Transmission electron micrographs of centrifuged samples denoted the presence of three major fractions showing the different types of particles integrated into the nanosuspensions. Furthermore, it was observed that not all the carnauba wax participated in the entrapment of the pigment. Regarding the amount of pigment being encapsulated or bonded by the wax-oil matrices, entrapment efficiencies higher than 85.52% were reported.

Surfactant -- Where Are We in 2003?

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JF Lewis

2004-01-01

Full Text Available Surfactant research has progressed over the past several years to the extent that exogenous surfactant administration in patients with the acute respiratory distress syndrome (ARDS is now being evaluated. Unfortunately, clinical responses have been variable, and we now need to take a look at how surfactant is altered in this disease so that more effective treatment strategies can be developed. This review briefly discusses the biophysical and host defense properties of surfactant, the impact of mechanical ventilation (MV on the endogenous surfactant system and the most recent clinical data involving exogenous surfactant administration in patients with ARDS. Discussions regarding future directions of surfactant research both in ARDS and diseases other than acute lung injury are included.

Thermodynamics of non-ionic surfactant Triton X-100-cationic surfactants mixtures at the cloud point

International Nuclear Information System (INIS)

Batigoec, Cigdem; Akbas, Halide; Boz, Mesut

2011-01-01

Highlights: → Non-ionic surfactants are used as emulsifier and solubilizate in such as textile, detergent and cosmetic. → Non-ionic surfactants occur phase separation at temperature as named the cloud point in solution. → Dimeric surfactants have attracted increasing attention due to their superior surface activity. → The positive values of ΔG cp 0 indicate that the process proceeds nonspontaneous. - Abstract: This study investigates the effects of gemini and conventional cationic surfactants on the cloud point (CP) of the non-ionic surfactant Triton X-100 (TX-100) in aqueous solutions. Instead of visual observation, a spectrophotometer was used for measurement of the cloud point temperatures. The thermodynamic parameters of these mixtures were calculated at different cationic surfactant concentrations. The gemini surfactants of the alkanediyl-α-ω-bis (alkyldimethylammonium) dibromide type, on the one hand, with different alkyl groups containing m carbon atoms and an ethanediyl spacer, referred to as 'm-2-m' (m = 10, 12, and 16) and, on the other hand, with -C 16 alkyl groups and different spacers containing s carbon atoms, referred to as '16-s-16' (s = 6 and 10) were synthesized, purified and characterized. Additions of the cationic surfactants to the TX-100 solution increased the cloud point temperature of the TX-100 solution. It was accepted that the solubility of non-ionic surfactant containing polyoxyethylene (POE) hydrophilic chain was a maximum at the cloud point so that the thermodynamic parameters were calculated at this temperature. The results showed that the standard Gibbs free energy (ΔG cp 0 ), the enthalpy (ΔH cp 0 ) and the entropy (ΔS cp 0 ) of the clouding phenomenon were found positive in all cases. The standard free energy (ΔG cp 0 ) increased with increasing hydrophobic alkyl chain for both gemini and conventional cationic surfactants; however, it decreased with increasing surfactant concentration.

MICROBIAL SURFACTANTS IN ENVIRONMENTAL TECHNOLOGIES

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T. P. Pirog

2015-08-01

Full Text Available It was shown literature and own experimental data concerning the use of microbial surface active glycolipids (rhamno-, sophoro- and trehalose lipids and lipopeptides for water and soil purification from oil and other hydrocarbons, removing toxic heavy metals (Cu2+, Cd2+, Ni2+, Pb2+, degradation of complex pollution (oil and other hydrocarbons with heavy metals, and the role of microbial surfactants in phytoremediation processes. The factors that limit the use of microbial surfactants in environmental technologies are discussed. Thus, at certain concentrations biosurfactant can exhibit antimicrobial properties and inhibit microorganisms destructing xenobiotics. Microbial biodegradability of surfactants may also reduce the effectiveness of bioremediation. Development of effective technologies using microbial surfactants should include the following steps: monitoring of contaminated sites to determine the nature of pollution and analysis of the autochthonous microbiota; determining the mode of surfactant introduction (exogenous addition of stimulation of surfactant synthesis by autochthonous microbiota; establishing an optimal concentration of surfactant to prevent exhibition of antimicrobial properties and rapid biodegradation; research both in laboratory and field conditions.

Two novel exonic point mutations in HEXA identified in a juvenile Tay-Sachs patient: role of alternative splicing and nonsense-mediated mRNA decay.

Science.gov (United States)

Levit, A; Nutman, D; Osher, E; Kamhi, E; Navon, R

2010-06-01

We have identified three mutations in the beta-hexoseaminidase A (HEXA) gene in a juvenile Tay-Sachs disease (TSD) patient, which exhibited a reduced level of HEXA mRNA. Two mutations are novel, c.814G>A (p.Gly272Arg) and c.1305C>T (p.=), located in exon 8 and in exon 11, respectively. The third mutation, c.1195A>G (p.Asn399Asp) in exon 11, has been previously characterized as a common polymorphism in African-Americans. Hex A activity measured in TSD Glial cells, transfected with HEXA cDNA constructs bearing these mutations, was unaltered from the activity level measured in normal HEXA cDNA. Analysis of RT-PCR products revealed three aberrant transcripts in the patient, one where exon 8 was absent, one where exon 11 was absent and a third lacking both exons 10 and 11. All three novel transcripts contain frameshifts resulting in premature termination codons (PTCs). Transfection of mini-gene constructs carrying the c.814G>A and c.1305C>T mutations proved that the two mutations result in exon skipping. mRNAs that harbor a PTC are detected and degraded by the nonsense-mediated mRNA decay (NMD) pathway to prevent synthesis of abnormal proteins. However, although NMD is functional in the patient's fibroblasts, aberrant transcripts are still present. We suggest that the level of correctly spliced transcripts as well as the efficiency in which NMD degrade the PTC-containing transcripts, apparently plays an important role in the phenotype severity of the unique patient and thus should be considered as a potential target for drug therapy.

Dynamic covalent surfactants

NARCIS (Netherlands)

Minkenberg, C.B.

2012-01-01

In this thesis the development of surfactant aggregates with fast exchange dynamics between the aggregated and non-aggregated state is described. Dynamic surfactant exchange plays an important role in natural systems, for instance in cell signaling, cell division, and uptake and release of cargo.

Lung surfactant levels are regulated by Ig-Hepta/GPR116 by monitoring surfactant protein D.

Directory of Open Access Journals (Sweden)

Taku Fukuzawa

Full Text Available Lung surfactant is a complex mixture of lipids and proteins, which is secreted from the alveolar type II epithelial cell and coats the surface of alveoli as a thin layer. It plays a crucial role in the prevention of alveolar collapse through its ability to reduce surface tension. Under normal conditions, surfactant homeostasis is maintained by balancing its release and the uptake by the type II cell for recycling and the internalization by alveolar macrophages for degradation. Little is known about how the surfactant pool is monitored and regulated. Here we show, by an analysis of gene-targeted mice exhibiting massive accumulation of surfactant, that Ig-Hepta/GPR116, an orphan receptor, is expressed on the type II cell and sensing the amount of surfactant by monitoring one of its protein components, surfactant protein D, and its deletion results in a pulmonary alveolar proteinosis and emphysema-like pathology. By a coexpression experiment with Sp-D and the extracellular region of Ig-Hepta/GPR116 followed by immunoprecipitation, we identified Sp-D as the ligand of Ig-Hepta/GPR116. Analyses of surfactant metabolism in Ig-Hepta(+/+ and Ig-Hepta(-/- mice by using radioactive tracers indicated that the Ig-Hepta/GPR116 signaling system exerts attenuating effects on (i balanced synthesis of surfactant lipids and proteins and (ii surfactant secretion, and (iii a stimulating effect on recycling (uptake in response to elevated levels of Sp-D in alveolar space.

Treatment with exogenous surfactant stimulates endogenous surfactant synthesis in premature infants with respiratory distress syndrome

NARCIS (Netherlands)

Bunt, JEH; Carnielli, VP; Janssen, DJ; Wattimena, JLD; Hop, WC; Sauer, PJ; Zimmermann, LJI

2000-01-01

Objective: Treatment of preterm infants with respiratory distress syndrome (RDS) with exogenous surfactant has greatly improved clinical outcome. Some infants require multiple doses, and it has not been studied whether these large amounts of exogenous surfactant disturb endogenous surfactant

Surfactant nebulisation : lung function, surfactant distribution and pulmonary blood flow distribution in lung lavaged rabbits

NARCIS (Netherlands)

Dijk, Peter H.; Heikamp, A; Bambang Oetomo, Sidarto

1997-01-01

Objective: Surfactant nebulisation is a promising alternative to surfactant instillation in newborns with the respiratory distress syndrome. Although less surfactant is deposited in the lung, it improves gas exchange, probably due to a superior distribution. We hypothesize that a more uniform

Surfactants from petroleum paraffin wax

Energy Technology Data Exchange (ETDEWEB)

Kassem, T.M.; Hussein, M.H.; El Sayed, A.S.

Paraffin wax from Egyptian petroleum was purified and then oxidized to fatty acids which were esterified to form their methyl esters, fractionated and then hydrolysed. The obtained fatty acids were converted into the corresponding primary amines which were converted with ethylene oxide to form nonionic surfactants. The prepared primary amines were also converted into tertiary amines and then converted into cationic surfactants through condensation with benzyl chloride or 1-chloromethylnaphthalene. Also, amine oxide surfactants were prepared by oxidation of the tertiary amines with hydrogen peroxide. The surface active properties of all the prepared surfactants were determined, and the effect of their chemical structure on the surfactant properties are discussed in this paper.

Acute Pathophysiological Effects of Intratracheal Instillation of Budesonide and Exogenous Surfactant in a Neonatal Surfactant-depleted Piglet Model

Directory of Open Access Journals (Sweden)

Chia-Feng Yang

2010-08-01

Conclusions: Intratracheal instillation of surfactant or surfactant plus budesonide can improve oxygenation and pulmonary histologic outcome in neonatal surfactant-depleted lungs. The additional use of budesonide does not disturb the function of the exogenous surfactant. Intratracheal administration of a corticosteroid combined with surfactant may be an effective method for alleviating local pulmonary inflammation in severe RDS.

Surfactant flooding of diesel-contaminated soils

International Nuclear Information System (INIS)

Peters, R.W.; Montemagno, C.D.; Shem, L.; Lewis, B.A.

1991-01-01

At one installation, approximately 60,000 gallons of No. 2 diesel fuel leaked into the subsurface environment, with contamination at depths of 6 to 34 m below the surface. Argonne National Laboratory was contracted to perform treatability studies for site remediation. The treatability studies focused on four separate phases: (1) leachability studies on the various contaminated soil borings, (2) air stripping studies, (3) bioremediation studies, and (4) surfactant screening/surfactant flooding studies. This paper summarizes the fourth phase of this research program after initial surfactant screening of 21 surfactants. Three of the surfactants were used for the surfactant flooding studies; the results from that phase of the research program are described

Identification of novel mutations in HEXA gene in children affected with Tay Sachs disease from India.

Directory of Open Access Journals (Sweden)

Mehul Mistri

Full Text Available Tay Sachs disease (TSD is a neurodegenerative disorder due to β-hexosaminidase A deficiency caused by mutations in the HEXA gene. The mutations leading to Tay Sachs disease in India are yet unknown. We aimed to determine mutations leading to TSD in India by complete sequencing of the HEXA gene. The clinical inclusion criteria included neuroregression, seizures, exaggerated startle reflex, macrocephaly, cherry red spot on fundus examination and spasticity. Neuroimaging criteria included thalamic hyperdensities on CT scan/T1W images of MRI of the brain. Biochemical criteria included deficiency of hexosaminidase A (less than 2% of total hexosaminidase activity for infantile patients. Total leukocyte hexosaminidase activity was assayed by 4-methylumbelliferyl-N-acetyl-β-D-glucosamine lysis and hexosaminidase A activity was assayed by heat inactivation method and 4-methylumbelliferyl-N-acetyl-β-D-glucosamine-6-sulphate lysis method. The exons and exon-intron boundaries of the HEXA gene were bidirectionally sequenced using an automated sequencer. Mutations were confirmed in parents and looked up in public databases. In silico analysis for mutations was carried out using SIFT, Polyphen2, MutationT@ster and Accelrys Discovery Studio softwares. Fifteen families were included in the study. We identified six novel missense mutations, c.340 G>A (p.E114K, c.964 G>A (p.D322N, c.964 G>T (p.D322Y, c.1178C>G (p.R393P and c.1385A>T (p.E462V, c.1432 G>A (p.G478R and two previously reported mutations. c.1277_1278insTATC and c.508C>T (p.R170W. The mutation p.E462V was found in six unrelated families from Gujarat indicating a founder effect. A previously known splice site mutation c.805+1 G>C and another intronic mutation c.672+30 T>G of unknown significance were also identified. Mutations could not be identified in one family. We conclude that TSD patients from Gujarat should be screened for the common mutation p.E462V.

Identification of novel mutations in HEXA gene in children affected with Tay Sachs disease from India.

Science.gov (United States)

Mistri, Mehul; Tamhankar, Parag M; Sheth, Frenny; Sanghavi, Daksha; Kondurkar, Pratima; Patil, Swapnil; Idicula-Thomas, Susan; Gupta, Sarita; Sheth, Jayesh

2012-01-01

Tay Sachs disease (TSD) is a neurodegenerative disorder due to β-hexosaminidase A deficiency caused by mutations in the HEXA gene. The mutations leading to Tay Sachs disease in India are yet unknown. We aimed to determine mutations leading to TSD in India by complete sequencing of the HEXA gene. The clinical inclusion criteria included neuroregression, seizures, exaggerated startle reflex, macrocephaly, cherry red spot on fundus examination and spasticity. Neuroimaging criteria included thalamic hyperdensities on CT scan/T1W images of MRI of the brain. Biochemical criteria included deficiency of hexosaminidase A (less than 2% of total hexosaminidase activity for infantile patients). Total leukocyte hexosaminidase activity was assayed by 4-methylumbelliferyl-N-acetyl-β-D-glucosamine lysis and hexosaminidase A activity was assayed by heat inactivation method and 4-methylumbelliferyl-N-acetyl-β-D-glucosamine-6-sulphate lysis method. The exons and exon-intron boundaries of the HEXA gene were bidirectionally sequenced using an automated sequencer. Mutations were confirmed in parents and looked up in public databases. In silico analysis for mutations was carried out using SIFT, Polyphen2, MutationT@ster and Accelrys Discovery Studio softwares. Fifteen families were included in the study. We identified six novel missense mutations, c.340 G>A (p.E114K), c.964 G>A (p.D322N), c.964 G>T (p.D322Y), c.1178C>G (p.R393P) and c.1385A>T (p.E462V), c.1432 G>A (p.G478R) and two previously reported mutations. c.1277_1278insTATC and c.508C>T (p.R170W). The mutation p.E462V was found in six unrelated families from Gujarat indicating a founder effect. A previously known splice site mutation c.805+1 G>C and another intronic mutation c.672+30 T>G of unknown significance were also identified. Mutations could not be identified in one family. We conclude that TSD patients from Gujarat should be screened for the common mutation p.E462V.

Tay-Sachs disease in an Arab family due to c.78G>A HEXA nonsense mutation encoding a p.W26X early truncation enzyme peptide.

Science.gov (United States)

Haghighi, Alireza; Masri, Amira; Kornreich, Ruth; Desnick, Robert J

2011-12-01

Tay-Sachs disease (TSD), a pan-ethnic, autosomal recessive, neurodegenerative, lysosomal disease, results from deficient β-hexosaminidase A activity due to β-hexosaminidase α-subunit (HEXA) mutations. Prenatal/premarital carrier screening programs in the Ashkenazi Jewish community have markedly reduced disease occurrence. We report the first Jordanian Arab TSD patient diagnosed by deficient β-hexosaminidase A activity. HEXA mutation analysis revealed homozygosity for a nonsense mutation, c.78G>A (p.W26X). Previously reported in Arab patients, this mutation is a candidate for TSD screening in Arab populations. Copyright © 2011 Elsevier Inc. All rights reserved.

Fluorescent visualization of a spreading surfactant

Energy Technology Data Exchange (ETDEWEB)

Fallest, David W; Lichtenberger, Adele M; Fox, Christopher J; Daniels, Karen E, E-mail: kdaniel@ncsu.ed [Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States)

2010-07-15

The spreading of surfactants on thin films is an industrially and medically important phenomenon, but the dynamics are highly nonlinear and visualization of the surfactant dynamics has been a long-standing experimental challenge. We perform the first quantitative, spatiotemporally resolved measurements of the spreading of an insoluble surfactant on a thin fluid layer. During the spreading process, we directly observe both the radial height profile of the spreading droplet and the spatial distribution of the fluorescently tagged surfactant. We find that the leading edge of a spreading circular layer of surfactant forms a Marangoni ridge in the underlying fluid, with a trough trailing the ridge as expected. However, several novel features are observed using the fluorescence technique, including a peak in the surfactant concentration that trails the leading edge, and a flat, monolayer-scale spreading film that differs from concentration profiles predicted by current models. Both the Marangoni ridge and the surfactant leading edge can be described to spread as R{approx}t{sup {delta}}. We find spreading exponents {delta}{sub H}{approx}0.30 and {delta}{sub {Gamma}}{approx}0.22 for the ridge peak and surfactant leading edge, respectively, which are in good agreement with theoretical predictions of {delta}=1/4. In addition, we observe that the surfactant leading edge initially leads the peak of the Marangoni ridge, with the peak later catching up to the leading edge.

Surfactant screening of diesel-contaminated soil

International Nuclear Information System (INIS)

Peters, R.W.; Montemagno, C.D.; Shem, L.; Lewis, B.-A.

1992-01-01

At one installation in California, approximately 60,000 gal of No. 2 diesel fuel leaked into the subsurface environment, resulting in contamination at depths from 6 to 34 m below the surface. Argonne National Laboratory was contracted to perform treatability studies for site remediation. This paper summarizes a surfactant screening/surfactant flooding research program in which 22 surfactants were screened for their effectiveness in mobilizing the organics from the contaminated soil prior to bioremediation. Anionic surfactants resulted in the greatest degree of diesel mobilization. The most promising surfactants will be employed on contaminated soil samples obtained from the site

Surfactant nebulization versus instillation during high frequency ventilation in surfactant-deficient rabbits

NARCIS (Netherlands)

Dijk, Peter H.; Heikamp, A; Bambang Oetomo, Sidarto

Surfactant nebulization improves lung function at low alveolar doses of surfactant. However, efficiency of nebulization is low, and lung deposition seems to depend on lung aeration. High frequency ventilation (HFV) has been shown to improve lung aeration. We hypothesize that the combination of HFV

Amide and Ester-Functionalized Humic Acid for Fuel Combustion Enhancement

Science.gov (United States)

Riggs, Mark

Humic acid is a class of naturally occurring molecules composed of large sheet-like regions of cyclic aromatic hydrocarbon networks with surface and edge functional groups including phenols, carboxylic acids, and epoxides. These naturally occurring molecules are found in brown coal deposits near lignite formations. Humic acid has gained attention from the scientific community as a precursor for graphene. Graphene is a 2-dimensional honeycomb structure of fully unsaturated carbon atoms that has exceptional material properties and inherent aromaticity. Graphene's incredible properties are matched by the difficulty associated with reproducibly manufacturing it on a large scale. This issue has limited the use of graphene for commercial applications. The polar functional groups of humic acid contribute to the hydrophilic nature of the molecule, limiting its miscibility in any alkyl-based solvent. Surfactants containing long alkyl chains can affect the miscibility of the molecule in an organic solvent. Surfactants are often difficult to remove from the system. It is theorized that alkylation of the functional sites of humic acid can affect the hydrophilic nature of the molecule, and effectively enable its dispersion into organic solvents without simultaneous incorporation of surfactants. This dissertation investigated the amidation and esterification of humic acid molecules extracted from leonardite. The resulting change in the modified humic acid dispersibility in organic solvents and its potential usage as a fuel additive were evaluated. Butyl, hexyl, octyl, and decyl amide-modified and ester-modified humic acids were synthesized. These products were characterized to confirm successful chemical reaction through thermogravimetric analysis, Fourier-transform infrared spectroscopy, and scanning electron microscopy. The decyl-modified humic acids remained suspended in kerosene mixtures for longer than 1 week. Other organo-humic acids showed varying degrees of flocculation

Next-generation DNA sequencing of HEXA: a step in the right direction for carrier screening

Science.gov (United States)

Hoffman, Jodi D; Greger, Valerie; Strovel, Erin T; Blitzer, Miriam G; Umbarger, Mark A; Kennedy, Caleb; Bishop, Brian; Saunders, Patrick; Porreca, Gregory J; Schienda, Jaclyn; Davie, Jocelyn; Hallam, Stephanie; Towne, Charles

2013-01-01

Tay-Sachs disease (TSD) is the prototype for ethnic-based carrier screening, with a carrier rate of ∼1/27 in Ashkenazi Jews and French Canadians. HexA enzyme analysis is the current gold standard for TSD carrier screening (detection rate ∼98%), but has technical limitations. We compared DNA analysis by next-generation DNA sequencing (NGS) plus an assay for the 7.6 kb deletion to enzyme analysis for TSD carrier screening using 74 samples collected from participants at a TSD family conference. Fifty-one of 74 participants had positive enzyme results (46 carriers, five late-onset Tay-Sachs [LOTS]), 16 had negative, and seven had inconclusive results. NGS + 7.6 kb del screening of HEXA found a pathogenic mutation, pseudoallele, or variant of unknown significance (VUS) in 100% of the enzyme-positive or obligate carrier/enzyme-inconclusive samples. NGS detected the B1 allele in two enzyme-negative obligate carriers. Our data indicate that NGS can be used as a TSD clinical carrier screening tool. We demonstrate that NGS can be superior in detecting TSD carriers compared to traditional enzyme and genotyping methodologies, which are limited by false-positive and false-negative results and ethnically focused, limited mutation panels, respectively, but is not ready for sole use due to lack of information regarding some VUS. PMID:24498621

Solubilization of Hydrophobic Dyes in Surfactant Solutions

Directory of Open Access Journals (Sweden)

Ali Reza Tehrani-Bagha

2013-02-01

Full Text Available In this paper, the use of surfactants for solubilization of hydrophobic organic dyes (mainly solvent and disperse dyes has been reviewed. The effect of parameters such as the chemical structures of the surfactant and the dye, addition of salt and of polyelectrolytes, pH, and temperature on dye solubilization has been discussed. Surfactant self-assemble into micelles in aqueous solution and below the concentration where this occurs—the critical micelle concentration (CMC—there is no solubilization. Above the CMC, the amount of solubilized dye increases linearly with the increase in surfactant concentration. It is demonstrated that different surfactants work best for different dyes. In general, nonionic surfactants have higher solubilization power than anionic and cationic surfactants. It is likely that the reason for the good performance of nonionic surfactants is that they allow dyes to be accommodated not only in the inner, hydrocarbon part of the micelle but also in the headgroup shell. It is demonstrated that the location of a dye in a surfactant micelle can be assessed from the absorption spectrum of the dye-containing micellar solution.

Attainment of barium hexa ferrite nanoparticles by a Pechini method

International Nuclear Information System (INIS)

Galvao, Sheila B.; Timoteo, Flavio Junior J.; Machado, Tercio G.; Souto, Kesia K.O.; Floreoto, Neide T.; Paskocimas, Carlos A.

2009-01-01

The barium hexa ferrites (BaFe 12 O 19 ) are used as a compound of materials applied in electronic devices, as medical devices, satellites, dada servers systems, wireless systems and others. The general properties are strongly related to the microstructure and morphology, and the particles size decrease results in advantages to the majority applications, mainly the high-tech thumbnail devices. These magnetic ceramic materials, with perovskite structure, are traditionally prepared my conventional oxide mixture synthesis. In this work was studied the nanoparticle synthesis of BaFe 12 O 19 by the precursors polymeric method (Pechini), using as precursors the barium carbonate and the iron nitrate, under different thermal treatment conditions. The samples were characterized by XRD, Raman spectroscopy, SEM, BET, DTA and TGA. The results presented the attainment of a monophasic powder with particles size around 100 nm. (author)

NMR study of the dynamics of cationic gemini surfactant 14-2-14 in mixed solutions with conventional surfactants.

Science.gov (United States)

Jiang, Yan; Lu, Xing-Yu; Chen, Hong; Mao, Shi-Zhen; Liu, Mai-Li; Luo, Ping-Ya; Du, You-Ru

2009-06-18

Three kinds of conventional surfactants, namely, two nonionic surfactants [polyethylene glycol (23) lauryl ether (Brij-35) and Triton X-100 (TX-100)], one cationic surfactant [n-tetradecyltrimethyl ammonium bromide (TTAB)], and an anionic surfactant [sodium n-dodecyl sulfate (SDS)}, were mixed into the quaternary ammonium gemini surfactant [C(14)H(29)N(+)(CH(3))(2)](2)(CH(2))(2).2Br(-) (14-2-14) in aqueous solution. The exchange rate constants between 14-2-14 molecules in the mixed micelles and those in the bulk solution were detected using two nuclear magnetic resonance (NMR) methods: one-dimensional (1D) line shape analysis and two-dimensional (2D) exchange spectroscopy (EXSY). The results obtained from these two methods were consistent. Both showed that mixing a nonionic conventional surfactant, either Brij-35 or TX-100, enhanced the exchange process between the 14-2-14 molecules in the mixed micelles and those in the bulk solution. In contrast, the anionic surfactant SDS and the cationic surfactant TTAB slowed the process slightly.

Next-generation DNA sequencing of HEXA: a step in the right direction for carrier screening

OpenAIRE

Hoffman, Jodi D; Greger, Valerie; Strovel, Erin T; Blitzer, Miriam G; Umbarger, Mark A; Kennedy, Caleb; Bishop, Brian; Saunders, Patrick; Porreca, Gregory J; Schienda, Jaclyn; Davie, Jocelyn; Hallam, Stephanie; Towne, Charles

2013-01-01

Tay-Sachs disease (TSD) is the prototype for ethnic-based carrier screening, with a carrier rate of ∼1/27 in Ashkenazi Jews and French Canadians. HexA enzyme analysis is the current gold standard for TSD carrier screening (detection rate ∼98%), but has technical limitations. We compared DNA analysis by next-generation DNA sequencing (NGS) plus an assay for the 7.6 kb deletion to enzyme analysis for TSD carrier screening using 74 samples collected from participants at a TSD family conference. ...

Pulmonary clearance of {sup 99m}Tc-DTPA in experimental surfactant dysfunction treated with surfactant installation

Energy Technology Data Exchange (ETDEWEB)

Nilsson, K.; John, J.; Lachmann, B.; Robertson, B.; Wollmer, P.

1997-02-01

Background: Breakdown of the alveolo-capillary barrier is a characteristic feature of respiratory distress syndrome. Restoration of alveolo-capillary barrier function may be an important aspect of surfactant replacement therapy. We examined the effect of surfactant installation on alveolo-capillary barrier function in an experimental model of surfactant dysfunction by measuring pulmonary clearance of {sup 99m}Tc-DTPA. Methods: Nineteen rabbits were tracheotomized and mechanically ventilated. Surfactant dysfunction was induced by administration of a synthetic detergent in aerosol form. Detergent was given to 13 rabbits; seven rabbits were then treated with installation of natural surfactant, whereas six rabbits received saline. Six rabbits were used as untreated controls. An aerosol of {sup 99m}Tc-DTPA was administered to all animals and the pulmonary clearance was measured with a gamma camera. Results: {sup 99m}Tc-DTPA cleared from the lungs with a half-life of 71{+-}22 min in the control animals, 21.4{+-}7.4 min in the surfactant-treated animals and 5.8{+-}1.5 min in the saline-treated animals. The difference in half-life between groups was highly significant (P<0.001). There was no change in arterial oxygenation or compliance in controls or in animals treated with saline. In animals treated with surfactant, a small transient reduction in arterial oxygen tension and a more long-standing reduction in compliance were observed. Conclusion: Surfactant treatment thus significantly attenuated the effect of detergent treatment but did not restore alveolo-capillary transfer of {sup 99m}Tc-DTPA to normal. (AU) 26 refs.

Surfactant protein A and surfactant protein D variation in pulmonary disease

DEFF Research Database (Denmark)

Sørensen, Grith Lykke; Husby, Steffen; Holmskov, Uffe

2007-01-01

Surfactant proteins A (SP-A) and D (SP-D) have been implicated in pulmonary innate immunity. The proteins are host defense lectins, belonging to the collectin family which also includes mannan-binding lectin (MBL). SP-A and SP-D are pattern-recognition molecules with the lectin domains binding...... lavage and blood have indicated associations with a multitude of pulmonary inflammatory diseases. In addition, accumulating evidence in mouse models of infection and inflammation indicates that recombinant forms of the surfactant proteins are biologically active in vivo and may have therapeutic potential...... in controlling pulmonary inflammatory disease. The presence of the surfactant collectins, especially SP-D, in non-pulmonary tissues, such as the gastrointestinal tract and genital organs, suggest additional actions located to other mucosal surfaces. The aim of this review is to summarize studies on genetic...

Adsorption of dimeric surfactants in lamellar silicates

Energy Technology Data Exchange (ETDEWEB)

Balcerzak, Mateusz; Pietralik, Zuzanna [Department of Macromolecular Physics, Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Domka, Ludwik [Department of Metalorganic Chemistry, Faculty of Chemistry, A. Mickiewicz University, Grunwaldzka 6, 60-780 Poznań (Poland); Skrzypczak, Andrzej [Institute of Chemical Technology, Poznań University of Technology, Berdychowo 4, 60-965 Poznań (Poland); Kozak, Maciej, E-mail: mkozak@amu.edu.pl [Department of Macromolecular Physics, Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland)

2015-12-01

Highlights: • The intercalation of dimeric surfactants changed the morphology of MMT samples. • XRD indicated structures formed by surfactant molecules in interlayer space. • The four-step thermal decomposition of dimeric surfactant, confirms intercalation. - Abstract: The adsorption of different types of cationic surfactants in lamellar silicates changes their surface character from hydrophilic to hydrophobic. This study was undertaken to obtain lamellar silicates modified by a series of novel dimeric (gemini) surfactants of different length alkyl chains and to characterise these organophilised materials. Synthetic sodium montmorillonite SOMASIF® ME 100 (M) and enriched bentonite of natural origin (Nanoclay – hydrophilic bentonite®) were organophilised with dimeric (gemini) surfactants (1,1′-(1,4-butanediyl)bis(alkoxymethyl)imidazolium dichlorides). As a result of surfactant molecule adsorption in interlamellar space, the d-spacing (d{sub 001}) increased from 0.97 nm (for the anhydrous structure) to 2.04 nm. A Fourier transform infrared spectroscopy (FTIR) analysis of the modified systems reveals bands assigned to the stretching vibrations of the CH{sub 2} and CH{sub 3} groups and the scissoring vibrations of the NH group from the structure of the dimeric surfactants. Thermogravimetric (TG) and derivative thermogravimetric (DTG) studies imply a four-stage process of surfactant decomposition. Scanning electron microscopy (SEM) images provide information on the influence of dimeric surfactant intercalation into the silicate structures. Particles of the modified systems show a tendency toward the formation of irregularly shaped agglomerates.

Biodegradation of surfactant bearing wastes

International Nuclear Information System (INIS)

Chitra, S.; Chandran, S.; Sasidhar, P.; Lal, K.B.; Amalraj, R.V.

1991-01-01

In nuclear industry, during decontamination of protective wears and contaminated materials, detergents are employed to bring down the level of radioactive contamination within safe limits. However, the surfactant present in these wastes interferes in the chemical treatment process, reducing the decontamination factor. Biodegradation is an efficient and ecologically safe method for surfactant removal. A surfactant degrading culture was isolated and inoculated separately into simulated effluents containing 1% yeast extract and 5-100 ppm sodium lauryl sulphate (SLS) and 1% yeast extract and 5-100 ppm of commercial detergent respectively. The growth of the bacterial culture and the degradation characteristics of the surfactant in the above effluents were monitored under both dynamic and static conditions. (author). 6 refs., 6 figs., 1 tab

Estimation hydrophilic-lipophilic balance number of surfactants

Energy Technology Data Exchange (ETDEWEB)

Pawignya, Harsa, E-mail: harsa-paw@yahoo.co.id [Chemical Engineering Department Diponegoro University (Indonesia); Chemical Engineering Departement University of Pembangunan Nasional Yogyakarta (Indonesia); Prasetyaningrum, Aji, E-mail: ajiprasetyaningrum@gmail.com; Kusworo, Tutuk D.; Pramudono, Bambang, E-mail: Pramudono2004@yahoo.com [Chemical Engineering Department Diponegoro University (Indonesia); Dyartanti, Endah R. [Chemical Engineering Department Diponegoro University (Indonesia); Chemical Enginering Departement Sebelas Maret University (Indonesia)

2016-02-08

Any type of surfactant has a hydrophilic-lipophilic balance number (HLB number) of different. There are several methods for determining the HLB number, with ohysical properties of surfactant (solubility cloud point and interfacial tension), CMC methods and by thermodynamics properties (Free energy Gibbs). This paper proposes to determined HLB numbers from interfelation methods. The result of study indicated that the CMC method described by Hair and Moulik espesially for nonionic surfactant. The application of exess Gibbs free energy and by implication activity coefficient provides the ability to predict the behavior of surfactants in multi component mixtures of different concentration. Determination of HLB number by solubility and cloud point parameter is spesific for anionic and nonionic surfactant but this methods not available for cationic surfactants.

Degradation of surfactants by sono-irradiation

International Nuclear Information System (INIS)

Ashokkumar, M.; Grieser, F.; Vinodgopal, K.

2000-01-01

Full text: The ultrasound induced decomposition of a commercially available polydisperse nonylphenol ethoxylate surfactant (Teric GN9) has been investigated. Nearly 90% mineralization and/or degradation into volatile products of the surfactant is achieved after sonication for 24 hours. Ultrasound has been found to be a useful tool to achieve a number of chemical processes. Linear and branched alkyl benzene sulfonates and alkyl nonylphenol ethoxylates are widely used surfactants which accumulated in the environment and contribute to a well-recognised pollution problem. We have investigated the use of ultrasound in the degradation of both types of surfactants with the aim of understanding the mechanism of degradation in order to optimise the decomposition process. In this presentation, we report on the sonochemical degradation of Teric GN9- polydisperse, a nonylphenol ethoxylate with an average of 9 ethylene oxide units. The ultrasound unit used for the degradation studies of the surfactant solutions was an Allied Signal (ELAC Nautik) RF generator and transducer with a plate diameter of 54.5 mm operated at 363 kHz in continuous wave mode at an intensity of 2 W/cm 2 . Ultrasound induced cavitation events generate primary radicals inside gas/vapour filled bubbles. Due to the extreme conditions (T ∼ 5000 K; P ∼ 100 atm) generated within the collapsing bubble, H and OH radicals are produced by the homolysis of water molecules, if water is the medium of sonication. These primary radicals attack the surfactant molecules adsorbed at the bubble/water interface. The initial rate of reaction of the surfactant was found to be dependent on the monomer concentration in solution below and above the critical micelle concentration of the surfactants. This result strongly suggests that the initial radical attack on the surfactants occurs at the cavitation bubble/solution interface, followed by oxidative decomposition and pyrolysis of volatile fragments of the surfactant within

Structural analysis of protein complexes with sodium alkyl sulfates by small-angle scattering and polyacrylamide gel electrophoresis.

Science.gov (United States)

Ospinal-Jiménez, Mónica; Pozzo, Danilo C

2011-02-01

Small-angle X-ray (SAXS) and neutron (SANS) scattering is used to probe the structure of protein-surfactant complexes in solution and to correlate this information with their performance in gel electrophoresis. Proteins with sizes between 6.5 to 116 kDa are denatured with sodium alkyl sulfates (SC(x)S) of variable tail lengths. Several combinations of proteins and surfactants are analyzed to measure micelle radii, the distance between micelles, the extension of the complex, the radius of gyration, and the electrophoretic mobility. The structural characterization shows that most protein-surfactant complexes can be accurately described as pearl-necklace structures with spherical micelles. However, protein complexes with short surfactants (SC(8)S) bind with micelles that deviate significantly from spherical shape. Sodium decyl (SC(10)S) and dodecyl (SC(12)S, more commonly abbreviated as SDS) sulfates result in the best protein separations in standard gel electrophoresis. Particularly, SC(10)S shows higher resolutions for complexes of low molecular weight. The systematic characterization of alkyl sulfate surfactants demonstrates that changes in the chain architecture can significantly affect electrophoretic migration so that protein-surfactant structures could be optimized for high resolution protein separations.

Poly(ethylene oxide) surfactant polymers.

Science.gov (United States)

Vacheethasanee, Katanchalee; Wang, Shuwu; Qiu, Yongxing; Marchant, Roger E

2004-01-01

We report on a series of structurally well-defined surfactant polymers that undergo surface-induced self-assembly on hydrophobic biomaterial surfaces. The surfactant polymers consist of a poly(vinyl amine) backbone with poly(ethylene oxide) and hexanal pendant groups. The poly(vinyl amine) (PVAm) was synthesized by hydrolysis of poly(N-vinyl formamide) following free radical polymerization of N-vinyl formamide. Hexanal and aldehyde-terminated poly(ethylene oxide) (PEO) were simultaneously attached to PVAm via reductive amination. Surfactant polymers with different PEO:hexanal ratios and hydrophilic/hydrophobic balances were prepared, and characterized by FT-IR, 1H-NMR and XPS spectroscopies. Surface active properties at the air/water interface were determined by surface tension measurements. Surface activity at a solid surface/water interface was demonstrated by atomic force microscopy, showing epitaxially molecular alignment for surfactant polymers adsorbed on highly oriented pyrolytic graphite. The surfactant polymers described in this report can be adapted for simple non-covalent surface modification of biomaterials and hydrophobic surfaces to provide highly hydrated interfaces.

Surfactant screening of diesel-contaminated soil

International Nuclear Information System (INIS)

Peters, R.W.; Shem, L.; Montemagno, C.D.; Lewis, B.

1991-01-01

At one installation, approximately 60,000 gal of No. 2 diesel fuel leaked into the subsurface environment, with contamination at depths of 6 to 34 m below the surface. Argonne National Laboratory was contracted to perform treatability studies for site remediation. The treatability studies focused on four separate phases: (1) leachability studies on the various contaminated soil borings, (2) air stripping studies, (3) bioremediation studies, and (4) surfactant screening/surfactant flooding studies. This paper summarizes the fourth phase of the research program in which 21 surfactants were screened for possible use to mobilize the organics from the contaminated soil prior to bioremediation. Anionic surfactants resulted in the greatest degree of diesel mobilization. The most promising surfactants will be employed on actual contaminated soil samples obtained from the site

The Effect Of Coupling Agent On Composite Magnet Characteristic Based On Hexa ferrite (Sr M/Ba M) With Polyester And Epoxy Binder

International Nuclear Information System (INIS)

Sudirman; Ridwan; Mujamilah; Karo Karo, Aloma; Handayani, Ari; Rukihati

2004-01-01

Magnetic composites are mixtures of hexa ferrite powder and non magnetic materials such as polymers as binders. These composites have been investigated because they are light, elastic, and cheap. In this study thermoset polymer (epoxy and polyester) were used as binders. Inside study of coupling agent added effect on mechanical properties, hardness and microstructure. The composites were prepared by mixture thermoset polymer epoxy or polyester with hexa ferrite powder Sr M (SrFe 12 O 19 ) or Ba M (BaFe 12 O 19 ) with volume fraction of 40,50 and 60 % v/v, coupling agent of the Tetra Isopropyl Titanate in the amount of 5 ml or 10 ml are added before mix turing of the thermoset polymer epoxy or polyester with hexa ferrite powder. The resulting composite were characterized mechanically (tensile strength), hardness and microstructure test. The results showed that the tensile strength and hardness of the composite magnet were increased by increasing the composition of magnetic powder, either Sr M or Ba M, it caused by microstructure of particle Sr M magnetic powder 1.6 μm in the form splinter, where as the Ba M magnetic powder 1,2 μm in nodular form. Thermoset polymer epoxy as binder have tensile strength and hardness is bigger than composite magnet based on polyester, either Sr M or Ba M. The addition of coupling agent is very influenced on the tensile strength and hardness composite magnet, the more coupling magnet addition causes the more tensile strength and hardness of the composite magnet

Dilute Surfactant Methods for Carbonate Formations

Energy Technology Data Exchange (ETDEWEB)

Kishore K. Mohanty

2006-02-01

There are many fractured carbonate reservoirs in US (and the world) with light oil. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). The process of using dilute anionic surfactants in alkaline solutions has been investigated in this work for oil recovery from fractured oil-wet carbonate reservoirs both experimentally and numerically. This process is a surfactant-aided gravity drainage where surfactant diffuses into the matrix, lowers IFT and contact angle, which decrease capillary pressure and increase oil relative permeability enabling gravity to drain the oil up. Anionic surfactants have been identified which at dilute concentration of 0.05 wt% and optimal salinity can lower the interfacial tension and change the wettability of the calcite surface to intermediate/water-wet condition as well or better than the cationic surfactant DTAB with a West Texas crude oil. The force of adhesion in AFM of oil-wet regions changes after anionic surfactant treatment to values similar to those of water-wet regions. The AFM topography images showed that the oil-wetting material was removed from the surface by the anionic surfactant treatment. Adsorption studies indicate that the extent of adsorption for anionic surfactants on calcite minerals decreases with increase in pH and with decrease in salinity. Surfactant adsorption can be minimized in the presence of Na{sub 2}CO{sub 3}. Laboratory-scale surfactant brine imbibition experiments give high oil recovery (20-42% OOIP in 50 days; up to 60% in 200 days) for initially oil-wet cores through wettability alteration and IFT reduction. Small (<10%) initial gas saturation does not affect significantly the rate of oil recovery in the imbibition process, but larger gas saturation decreases the oil recovery rate. As the core permeability decreases, the rate of oil recovery reduces

Surfactant gene polymorphisms and interstitial lung diseases

Directory of Open Access Journals (Sweden)

Pantelidis Panagiotis

2001-11-01

Full Text Available Abstract Pulmonary surfactant is a complex mixture of phospholipids and proteins, which is present in the alveolar lining fluid and is essential for normal lung function. Alterations in surfactant composition have been reported in several interstitial lung diseases (ILDs. Furthermore, a mutation in the surfactant protein C gene that results in complete absence of the protein has been shown to be associated with familial ILD. The role of surfactant in lung disease is therefore drawing increasing attention following the elucidation of the genetic basis underlying its surface expression and the proof of surfactant abnormalities in ILD.

Formation and characterization of zein-propylene glycol alginate-surfactant ternary complexes: Effect of surfactant type.

Science.gov (United States)

Dai, Lei; Sun, Cuixia; Wei, Yang; Zhan, Xinyu; Mao, Like; Gao, Yanxiang

2018-08-30

In this study, zein, propylene glycol alginate (PGA) and surfactant ternary complexes were fabricated by antisolvent co-precipitation method. Two types of surfactants (rhamnolipid and lecithin) were applied to generate zein-PGA-rhamnolipid (Z-P-R) and zein-PGA-lecithin (Z-P-L) ternary complexes, respectively. Results showed that the surfactant types significantly affected the properties of ternary complexes. The formation of ternary complexes was mainly due to the non-covalent interactions such as hydrogen bonding, electrostatic interaction and hydrophobic interactions among zein, PGA and surfactants. Moreover, the thermal stability of ternary complexes was enhanced with increasing the levels of both surfactants. Notably, ternary complex dispersions exhibited better stability against pH from 2 to 8. Furthermore, a compact network structure was observed in Z-P-R ternary complex, while Z-P-L ternary complex remained the spherical structure. These findings would provide new insights into the development of novel delivery system and expand the options, when zein-based complexes were utilized under different environment conditions. Copyright © 2018 Elsevier Ltd. All rights reserved.

Biomimicry of surfactant protein C.

Science.gov (United States)

Brown, Nathan J; Johansson, Jan; Barron, Annelise E

2008-10-01

Since the widespread use of exogenous lung surfactant to treat neonatal respiratory distress syndrome, premature infant survival and respiratory morbidity have dramatically improved. Despite the effectiveness of the animal-derived surfactant preparations, there still remain some concerns and difficulties associated with their use. This has prompted investigation into the creation of synthetic surfactant preparations. However, to date, no clinically used synthetic formulation is as effective as the natural material. This is largely because the previous synthetic formulations lacked analogues of the hydrophobic proteins of the lung surfactant system, SP-B and SP-C, which are critical functional constituents. As a result, recent investigation has turned toward the development of a new generation of synthetic, biomimetic surfactants that contain synthetic phospholipids along with a mimic of the hydrophobic protein portion of lung surfactant. In this Account, we detail our efforts in creating accurate mimics of SP-C for use in a synthetic surfactant replacement therapy. Despite SP-C's seemingly simple structure, the predominantly helical protein is extraordinarily challenging to work with given its extreme hydrophobicity and structural instability, which greatly complicates the creation of an effective SP-C analogue. Drawing inspiration from Nature, two promising biomimetic approaches have led to the creation of rationally designed biopolymers that recapitulate many of SP-C's molecular features. The first approach utilizes detailed SP-C structure-activity relationships and amino acid folding propensities to create a peptide-based analogue, SP-C33. In SP-C33, the problematic and metastable polyvaline helix is replaced with a structurally stable polyleucine helix and includes a well-placed positive charge to prevent aggregation. SP-C33 is structurally stable and eliminates the association propensity of the native protein. The second approach follows the same design

Remediation using trace element humate surfactant

Energy Technology Data Exchange (ETDEWEB)

Riddle, Catherine Lynn; Taylor, Steven Cheney; Bruhn, Debra Fox

2016-08-30

A method of remediation at a remediation site having one or more undesirable conditions in which one or more soil characteristics, preferably soil pH and/or elemental concentrations, are measured at a remediation site. A trace element humate surfactant composition is prepared comprising a humate solution, element solution and at least one surfactant. The prepared trace element humate surfactant composition is then dispensed onto the remediation site whereby the trace element humate surfactant composition will reduce the amount of undesirable compounds by promoting growth of native species activity. By promoting native species activity, remediation occurs quickly and environmental impact is minimal.

Synthesis of carbohydrate-based surfactants

Energy Technology Data Exchange (ETDEWEB)

Pemberton, Jeanne E.; Polt, Robin L.; Maier, Raina M.

2016-11-22

The present invention provides carbohydrate-based surfactants and methods for producing the same. Methods for producing carbohydrate-based surfactants include using a glycosylation promoter to link a carbohydrate or its derivative to a hydrophobic compound.

Small angle neutron scattering study of doxorubicin–surfactant ...

Indian Academy of Sciences (India)

The binding affinity of doxorubicin within the micelle carrier is enhanced through complex formation of drug and anionic surfactant, aerosol OT (AOT). Electrostatic binding of doxorubicin with negatively charged surfactants leads to the formation of hydrophobic drug–surfactant complexes. Surfactant-induced partitioning of ...

DNA compaction by azobenzene-containing surfactant

International Nuclear Information System (INIS)

Zakrevskyy, Yuriy; Kopyshev, Alexey; Lomadze, Nino; Santer, Svetlana; Morozova, Elena; Lysyakova, Ludmila; Kasyanenko, Nina

2011-01-01

We report on the interaction of cationic azobenzene-containing surfactant with DNA investigated by absorption and fluorescence spectroscopy, dynamic light scattering, and atomic force microscopy. The properties of the surfactant can be controlled with light by reversible switching of the azobenzene unit, incorporated into the surfactant tail, between a hydrophobic trans (visible irradiation) and a hydrophilic cis (UV irradiation) configuration. The influence of the trans-cis isomerization of the azobenzene on the compaction process of DNA molecules and the role of both isomers in the formation and colloidal stability of DNA-surfactant complexes is discussed. It is shown that the trans isomer plays a major role in the DNA compaction process. The influence of the cis isomer on the DNA coil configuration is rather small. The construction of a phase diagram of the DNA concentration versus surfactant/DNA charge ratio allows distancing between three major phases: colloidally stable and unstable compacted globules, and extended coil conformation. There is a critical concentration of DNA above which the compacted globules can be hindered from aggregation and precipitation by adding an appropriate amount of the surfactant in the trans configuration. This is because of the compensation of hydrophobicity of the globules with an increasing amount of the surfactant. Below the critical DNA concentration, the compacted globules are colloidally stable and can be reversibly transferred with light to an extended coil state.

Viscosity of the oil-in-water Pickering emulsion stabilized by surfactant-polymer and nanoparticle-surfactant-polymer system

Science.gov (United States)

Sharma, Tushar; Kumar, G. Suresh; Chon, Bo Hyun; Sangwai, Jitendra S.

2014-11-01

Information on the viscosity of Pickering emulsion is required for their successful application in upstream oil and gas industry to understand their stability at extreme environment. In this work, a novel formulation of oil-in-water (o/w) Pickering emulsion stabilized using nanoparticle-surfactant-polymer (polyacrylamide) system as formulated in our earlier work (Sharma et al., Journal of Industrial and Engineering Chemistry, 2014) is investigated for rheological stability at high pressure and high temperature (HPHT) conditions using a controlled-strain rheometer. The nanoparticle (SiO2 and clay) concentration is varied from 1.0 to 5.0 wt%. The results are compared with the rheological behavior of simple o/w emulsion stabilized by surfactant-polymer system. Both the emulsions exhibit non-Newtonian shear thinning behavior. A positive shift in this behavior is observed for surfactant-polymer stabilized emulsion at high pressure conditions. Yield stress is observed to increase with pressure for surfactant-polymer emulsion. In addition, increase in temperature has an adverse effect on the viscosity of emulsion stabilized by surfactant-polymer system. In case of nanoparticle-surfactant-polymer stabilized o/w emulsion system, the viscosity and yield stress are predominantly constant for varying pressure and temperature conditions. The viscosity data for both o/w emulsion systems are fitted by the Herschel-Bulkley model and found to be satisfactory. In general, the study indicates that the Pickering emulsion stabilized by nanoparticle-surfactant-polymer system shows improved and stable rheological properties as compared to conventional emulsion stabilized by surfactant-polymer system indicating their successful application for HPHT environment in upstream oil and gas industry.

μ-Hexa-thio-metadiphosphato-bis-[(1,4,7,10,13,16-hexa-oxa-cyclo-octa-decane-κ(6) O)rubidium] aceto-nitrile disolvate.

Science.gov (United States)

Gjikaj, Mimoza; Pook, Niels-Patrick; Qarri, Flora

2013-12-01

The asymmetric unit of the title compound, [Rb2(P2S6)(C12H24O6)2]·2CH3CN, contains one half of an [Rb(18-crown-6)2]2[P2S6] unit and one aceto-nitrile solvent mol-ecule. The [Rb(18-crown-6)]2[P2S6] unit is completed by inversion symmetry. Its Rb(+) ion is situated near the centre of the macrocyclic cavity, but is displaced by 0.8972 (1) Å from the O atoms of the crown in the direction of the [P2S6](2-) moiety. The overall coordination number of the cation is eight, defined by the six crown ether O atoms and by two terminal S atoms of the [P2S6](2-) anion. The hexa-thio-metadiphosphate anion is built up from two tetra-hedral PS4 units joined together by a common edge. The crystal structure is characterized by alternating layers of [Rb(18-crown-6)]2[P2S6] and aceto-nitrile solvent mol-ecules stacked along [010].

Binding of cationic surfactants to humic substances

NARCIS (Netherlands)

Ishiguro, M.; Tan, W.; Koopal, L.K.

2007-01-01

Commercial surfactants are introduced into the environment either through waste products or site-specific contamination. The amphiphilic nature of both surfactants and humic substances (HS) leads to their mutual attraction especially when surfactant and HS are oppositely charged. Binding of the

Neutron spin-echo investigation of the microemulsion dynamics. in bicontinuous lamellar and droplet phases

CERN Document Server

Mihailescu, M; Endo, H; Allgaier, J; Gompper, G; Stellbrink, J; Richter, D; Jakobs, B; Sottmann, T; Faragó, B

2002-01-01

Using neutron spin-echo (NSE) spectroscopy in combination with dynamic light scattering (DLS), we performed an extensive investigation of the bicontinuous phase in ternary water-surfactant-oil microemulsions, with extension to lamellar and droplet phases. The dynamical behavior of surfactant monolayers of decyl-polyglycol-ether (C sub 1 sub 0 E sub 4) molecules, or mixtures of surfactant with long amphiphilic block-copolymers of type poly-ethylene propylene/poly-ethylene oxide (PEP-PEO) was studied, under comparable conditions. The investigation techniques provide access to different length scales relative to the characteristic periodicity length of the microemulsion structure. Information on the elastic bending modulus is obtained from the local scale dynamics in view of existing theoretical descriptions and is found to be in accordance with small angle neutron scattering (SANS) studies. Evidence for the modified elastic properties and additional interaction of the amphiphilic layers due to the polymer is mo...

pH regulation of the kinetic stability of the lipase from Thermomyces lanuginosus

DEFF Research Database (Denmark)

Wang, H.; Andersen, Kell Kleiner; Sehgal, P.

2013-01-01

Thermomyces lanuginosus lipase (TlL) is a kinetically stable protein, resistant toward both denaturation and refolding in the presence of the ionic surfactant sodium dodecyl sulfate (SDS) and the nonionic surfactant decyl maltoside (DecM). We investigate the pH dependence of this kinetic stability....... At pH 8, TlL remains folded and enzymatically active at multimillimolar surfactant concentrations but fails to refold from the acid urea-denatured state at submillimolar concentrations of SDS and DecM, indicating a broad concentration range of kinetic trapping or hysteresis. At pH 8, very few SDS...... molecules bind to TlL. The hysteresis SDS concentration range shrinks when moving to pH 4–6; in this pH range, SDS binds as micellelike clusters. Although hysteresis can be eliminated by reducing disulfide bonds, destabilizing the native state, and lowering the unfolding activation barrier, SDS sensitivity...

Surfactants tailored by the class Actinobacteria

Science.gov (United States)

Kügler, Johannes H.; Le Roes-Hill, Marilize; Syldatk, Christoph; Hausmann, Rudolf

2015-01-01

Globally the change towards the establishment of a bio-based economy has resulted in an increased need for bio-based applications. This, in turn, has served as a driving force for the discovery and application of novel biosurfactants. The class Actinobacteria represents a vast group of microorganisms with the ability to produce a diverse range of secondary metabolites, including surfactants. Understanding the extensive nature of the biosurfactants produced by actinobacterial strains can assist in finding novel biosurfactants with new potential applications. This review therefore presents a comprehensive overview of the knowledge available on actinobacterial surfactants, the chemical structures that have been completely or partly elucidated, as well as the identity of the biosurfactant-producing strains. Producer strains of not yet elucidated compounds are discussed, as well as the original habitats of all the producer strains, which seems to indicate that biosurfactant production is environmentally driven. Methodology applied in the isolation, purification and structural elucidation of the different types of surface active compounds, as well as surfactant activity tests, are also discussed. Overall, actinobacterial surfactants can be summarized to include the dominantly occurring trehalose-comprising surfactants, other non-trehalose containing glycolipids, lipopeptides and the more rare actinobacterial surfactants. The lack of structural information on a large proportion of actinobacterial surfactants should be considered as a driving force to further explore the abundance and diversity of these compounds. This would allow for a better understanding of actinobacterial surface active compounds and their potential for biotechnological application. PMID:25852670

Surfactants tailored by the class Actinobacteria

Directory of Open Access Journals (Sweden)

Johannes H Kügler

2015-03-01

Full Text Available Gloablly, the drive towards the establishment of a bio-based economy has resulted in an increased need for bio-based applications. This, in turn, has served as a driving force for the discovery and application of novel biosurfactants. The class Actinobacteria represents a vast group of microorganisms with the ability to produce a diverse range of secondary metabolites, including surfactants. Understanding the extensive nature of the biosurfactants produced by actinobacterial strains can assist in finding novel biosurfactants with new potential applications. This review therefore presents a comprehensive overview of the knowledge available on actinobacterial surfactants, the chemical structures that have been completely or partly elucidated, as well as the identity of the biosurfactant-producing strains. Producer strains of not yet elucidated compounds are discussed, as well as the original habitats of all the producer strains, which seems to indicate that biosurfactant production is environmentally driven. Methodology applied in the isolation, purification and structural elucidation of the different types of surface active compounds, as well as surfactant activity tests, are also discussed. Overall, actinobacterial surfactants can be summarized to include the dominantly occurring trehalose-comprising surfactants, other non-trehalose containing glycolipids, lipopeptides and the more rare actinobacterial surfactants. The lack of structural information on a large proportion of actinobacterial surfactants should be considered as a driving force to further explore the abundance and diversity of these compounds. This would allow for a better understanding of actinobacterial surface active compounds and their potential for biotechnological application.

In vitro surfactant structure-toxicity relationships: implications for surfactant use in sexually transmitted infection prophylaxis and contraception.

Directory of Open Access Journals (Sweden)

Ângela S Inácio

Full Text Available BACKGROUND: The need for woman-controlled, cheap, safe, effective, easy-to-use and easy-to-store topical applications for prophylaxis against sexually transmitted infections (STIs makes surfactant-containing formulations an interesting option that requires a more fundamental knowledge concerning surfactant toxicology and structure-activity relationships. METHODOLOGY/PRINCIPAL FINDINGS: We report in vitro effects of surfactant concentration, exposure time and structure on the viability of mammalian cell types typically encountered in the vagina, namely, fully polarized and confluent epithelial cells, confluent but non-polarized epithelial-like cells, dendritic cells, and human sperm. Representatives of the different families of commercially available surfactants--nonionic (Triton X-100 and monolaurin, zwitterionic (DDPS, anionic (SDS, and cationic (C(nTAB (n = 10 to 16, C(12PB, and C(12BZK--were examined. Triton X-100, monolaurin, DDPS and SDS were toxic to all cell types at concentrations around their critical micelle concentration (CMC suggesting a non-selective mode of action involving cell membrane destabilization and/or destruction. All cationic surfactants were toxic at concentrations far below their CMC and showed significant differences in their toxicity toward polarized as compared with non-polarized cells. Their toxicity was also dependent on the chemical nature of the polar head group. Our results suggest an intracellular locus of action for cationic surfactants and show that their structure-activity relationships could be profitably exploited for STI prophylaxis in vaginal gel formulations. The therapeutic indices comparing polarized epithelial cell toxicity to sperm toxicity for all surfactants examined, except C(12PB and C(12BZK, does not justify their use as contraceptive agents. C(12PB and C(12BZK are shown to have a narrow therapeutic index recommending caution in their use in contraceptive formulations. CONCLUSIONS

Next Generation Surfactants for Improved Chemical Flooding Technology

Energy Technology Data Exchange (ETDEWEB)

Laura Wesson; Prapas Lohateeraparp; Jeffrey Harwell; Bor-Jier Shiau

2012-05-31

The principle objective of this project was to characterize and test current and next generation high performance surfactants for improved chemical flooding technology, focused on reservoirs in the Pennsylvanian-aged (Penn) sands. In order to meet this objective the characteristic curvatures (Cc) of twenty-eight anionic surfactants selected for evaluation for use in chemical flooding formulations were determined. The Cc values ranged from -6.90 to 2.55 with the majority having negative values. Crude oil samples from nine Penn sand reservoirs were analyzed for several properties pertinent to surfactant formulation for EOR application. These properties included equivalent alkane carbon numbers, total acid numbers, and viscosity. The brine samples from these same reservoirs were analyzed for several cations and for total dissolved solids. Surfactant formulations were successfully developed for eight reservoirs by the end of the project period. These formulations were comprised of a tertiary mixture of anionic surfactants. The identities of these surfactants are considered proprietary, but suffice to say the surfactants in each mixture were comprised of varying chemical structures. In addition to the successful development of surfactant formulations for EOR, there were also two successful single-well field tests conducted. There are many aspects that must be considered in the development and implementation of effective surfactant formulations. Taking into account these other aspects, there were four additional studies conducted during this project. These studies focused on the effect of the stability of surfactant formulations in the presence of polymers with an associated examination of polymer rheology, the effect of the presence of iron complexes in the brine on surfactant stability, the potential use of sacrificial agents in order to minimize the loss of surfactant to adsorption, and the effect of electrolytes on surfactant adsorption. In these last four studies

The Molecular Era of Surfactant Biology

OpenAIRE

Whitsett, Jeffrey A.

2014-01-01

Advances in the physiology, biochemistry, molecular and cell biology of the pulmonary surfactant system transformed the clinical care and outcome of preterm infants with respiratory distress syndrome. The molecular era of surfactant biology provided genetic insights into the pathogenesis of pulmonary disorders, previously termed “idiopathic” that affect newborn infants, children and adults. Knowledge related to the structure and function of the surfactant proteins and their roles in alveolar ...

Nanoparticle-enabled delivery of surfactants in porous media.

Science.gov (United States)

Nourafkan, Ehsan; Hu, Zhongliang; Wen, Dongsheng

2018-06-01

The adsorption of surfactants on the reservoir rocks surface is a serious issue in many energy and environment related areas. Learning from the concept of drug delivery in the nano-medicine field, this work proposes and validates the concept of using nanoparticles to deliver a mixture of surfactants into a porous medium. TiO 2 nanoparticles (NPs) are used as carriers for a blend of surfactants mixtures including anionic alkyl aryl sulfonic acid (AAS) and nonionic alcohol ethoxylated (EA) at the optimum salinity and composition conditions. The transport of NPs through a core sample of crushed sandstone grains and the adsorption of surfactants are evaluated. By using TiO 2 NPs, the adsorption of surfactant molecules can be significantly reduced, i.e. half of the initial adsorption value. The level of surfactant adsorption reduction is related to the NPs transport capability through the porous medium. An application study shows that comparing to surfactant flooding alone, the total oil recovery can be increased by 7.81% of original oil in place (OOIP) by using nanoparticle bonded surfactants. Such work shows the promise of NP as an effective surfactant carrier for sandstone reservoirs, which could have many potential applications in enhanced oil recovery (EOR) and environmental remediation. Copyright © 2018 Elsevier Inc. All rights reserved.

Comparison of rSP-C surfactant with natural and synthetic surfactants after late treatment in a rat model of the acute respiratory distress syndrome

Science.gov (United States)

Häfner, Dietrich; Germann, Paul-Georg; Hauschke, Dieter

1998-01-01

In a previous paper we showed that an SP-C containing surfactant preparation has similar activity as bovine-derived surfactants in a rat lung lavage model of the adult respiratory distress syndrome. In this study surfactant was given ten minutes after the last lavage (early treatment). In the present investigation we were interested how different surfactant preparations behave when they are administered 1 h after the last lavage (late treatment). Four protein containing surfactants (rSP-C surfactant, bLES, Infasurf and Survanta) were compared with three protein-free surfactants (ALEC, Exosurf and the phospholipid (PL) mixture of the rSP-C surfactant termed PL surfactant) with respect to their ability to improve gas exchange in this more stringent model when surfactant is given one hour after the last lavage. For better comparison of the surfactants the doses were related to phospholipids. The surfactants were given at doses of 25, 50 and 100 mg kg−1 body weight. The surfactants were compared to an untreated control group that was only ventilated for the whole experimental period. Tracheotomized rats (8–12 per dose and surfactant) were pressure-controlled ventilated (Siemens Servo Ventilator 900C) with 100% oxygen at a respiratory rate of 30 breaths min−1, inspiration expiration ratio of 1 : 2, peak inspiratory pressure of 28 cmH2O at positive endexpiratory pressure (PEEP) of 8 cmH2O. Animals were ventilated for one hour after the last lavage and thereafter the surfactants were intratracheally instilled. During the whole experimental period the ventilation was not changed. Partial arterial oxygen pressures (PaO2, mmHg) at 30 min and 120 min after treatment were used for statistical comparison. All protein containing surfactants caused a dose-dependent increase of the reduced PaO2 values at 30 min after treatment. The protein-free surfactants showed only weak dose-dependent increase in PaO2 values at this time. This difference between the

Surfactant modified clays’ consistency limits and contact angles

Directory of Open Access Journals (Sweden)

S Akbulut

2012-07-01

Full Text Available This study was aimed at preparing a surfactant modified clay (SMC and researching the effect of surfactants on clays' contact angles and consistency limits; clay was thus modified by surfactants formodifying their engineering properties. Seven surfactants (trimethylglycine, hydroxyethylcellulose  octyl phenol ethoxylate, linear alkylbenzene sulfonic acid, sodium lauryl ether sulfate, cetyl trimethylammonium chloride and quaternised ethoxylated fatty amine were used as surfactants in this study. The experimental results indicated that SMC consistency limits (liquid and plastic limits changedsignificantly compared to those of natural clay. Plasticity index and liquid limit (PI-LL values representing soil class approached the A-line when zwitterion, nonionic, and anionic surfactant percentageincreased. However, cationic SMC became transformed from CH (high plasticity clay to MH (high plasticity silt class soils, according to the unified soil classification system (USCS. Clay modifiedwith cationic and anionic surfactants gave higher and lower contact angles than natural clay, respectively.

Probing dynamics and mechanism of exchange process of quaternary ammonium dimeric surfactants, 14-s-14, in the presence of conventional surfactants.

Science.gov (United States)

Liu, Jun; Jiang, Yan; Chen, Hong; Mao, Shi Zhen; Du, You Ru; Liu, Mai Li

2012-12-27

In this Article, we investigated effects of different types of conventional surfactants on exchange dynamics of quaternary ammonium dimeric surfactants, with chemical formula C(14)H(29)N(+)(CH(3))(2)- (CH(2))(s)-N(+)(CH(3))(2)C(14)H(29)·2Br(-), or 14-s-14 for short. Two nonionic surfactants, TritonX-100 (TX-100) and polyethylene glycol (23) laurylether (Brij-35), and one cationic surfactant, n-tetradecyltrimethyl ammonium bromide (TTAB), and one ionic surfactant, sodium dodecyl sulfate (SDS) were chosen as typical conventional surfactants. Exchange rates of 14-s-14 (s = 2, 3, and 4) between the micelle form and monomer in solution were detected by two NMR methods: one-dimensional (1D) line shape analysis and two-dimensional (2D) exchange spectroscopy (EXSY). Results show that the nonionic surfactants (TX-100 and Brij-35), the cationic surfactant (TTAB), and the ionic surfactant (SDS) respectively accelerated, barely influenced, and slowed the exchange rate of 14-s-14. The effect mechanism was investigated by the self-diffusion experiment, relaxation time measurements (T(2)/T(1)), the fluorescence experiment (I(1)/I(3)) and observed chemical shift variations. Results reveal that, nonionic conventional surfactants (TX-100 and Brij-35) loosened the molecule arrangement and decreased hydrophobic interactions in the micelle, and thus accelerated the exchange rate of 14-s-14. The cationic conventional surfactant (TTAB) barely changed the molecule arrangement and thus barely influenced the exchange rate of 14-s-14. The ionic conventional surfactant (SDS) introduced the electrostatic attraction effect, tightened the molecule arrangement, and increased hydrophobic interactions in the micelle, and thus slowed down the exchange rate of 14-s-14. Additionally, the two-step exchange mechanism of 14-s-14 in the mixed solution was revealed through interesting variation tendencies of exchange rates of 14-s-14.

Effects of Surfactant on Geotechnical Characteristics of Silty Soil

International Nuclear Information System (INIS)

Rahman, Z.A.; Sahibin, A.R.; Lihan, T.; Idris, W.M.R.; Sakina, M.

2013-01-01

Surfactants are often used as a cleaning agent for restoration of oil-contaminated soil. However the effect of surfactant on the geotechnical properties of soil is not clearly understood. In this study, the effects of surfactant on silty soil were investigated for consistency index, compaction, permeability and shear strength. Sodium dodecyl sulfate (SDS) was used in this study to prepare the surfactant-treated soil. Our results showed that the soil with added surfactant exhibited a decrease in liquid and plastic limit values. Maximum dry densities increased and optimum moisture contents decreased as contents of added surfactant were increased. The presence of surfactant assists the soil to achieve maximum density at lower water content. The addition of surfactant decreased the permeability of soil from 6.29 x 10 -4 to 1.15 x 10 -4 ms -1 . The shear strength of soil with added surfactant was examined using the undrained unconsolidated triaxial tests. The results showed that the undrained shear strength, Cu was significantly affected, decreased from 319 kPa to 50 kPa for soil with 20 % of added surfactant. The results of this study showed that the presence of surfactant in soil can modify the mechanical behaviour of the soil. (author)

Surfactant-enhanced control of track-etch pore morphology

International Nuclear Information System (INIS)

Apel', P.Yu.; Blonskaya, I.V.; Didyk, A.Yu.; Dmitriev, S.N.; Orelovich, O.L.; Samojlova, L.I.; Vutsadakis, V.A.; Root, D.

2000-01-01

The influence of surfactants on the process of chemical development of ion tracks in polymers is studied. Based on the experimental data, a mechanism of the surfactant effect on the track-etch pore morphology is proposed. In the beginning of etching the surfactant is adsorbed on the surface and creates a layer that is quasi-solid and partially protects the surface from the etching agent. However, some etchant molecules diffuse through the barrier and react with the polymer surface. This results in the formation of a small hole at the entrance to the ion track. After the hole has attained a few annometers in diameter, the surfactant molecules penetrate into the track and cover its walls. Further diffusion of the surfactant into the growing pore is hindered. The adsorbed surfactant layer is not permeable for large molecules. In contrast, small alkali molecules and water molecules diffuse into the track and provide the etching process enlarging the pore. At this stage the transport of the surfactant into the pore channel can proceed only due to the lateral diffusion in the adsorbed layer. The volume inside the pore is free of surfactant molecules and grows at a higher rate than pore entrance. After a more prolonged etching the bottle-like (or 'cigar-like') pore channels are formed. The bottle-like shape of the pore channels depends on the etching conditions such as alkali and surfactant concentration, temperature, and type of the surfactant. The use of surfactants enables one to produce track-etch membranes with improved flow rate characteristics compared with those having cylindrical pores with the same nominal pore diameters

Open lung ventilation preserves the response to delayed surfactant treatment in surfactant-deficient newborn piglets

NARCIS (Netherlands)

van Veenendaal, Mariëtte B.; van Kaam, Anton H.; Haitsma, Jack J.; Lutter, René; Lachmann, Burkhard

2006-01-01

OBJECTIVE: Delayed surfactant treatment (>2 hrs after birth) is less effective than early treatment in conventionally ventilated preterm infants with respiratory distress syndrome. The objective of this study was to evaluate if this time-dependent efficacy of surfactant treatment is also present

Influence of surfactants in forced dynamic dewetting.

Science.gov (United States)

Henrich, Franziska; Fell, Daniela; Truszkowska, Dorota; Weirich, Marcel; Anyfantakis, Manos; Nguyen, Thi-Huong; Wagner, Manfred; Auernhammer, Günter K; Butt, Hans-Jürgen

2016-09-20

In this work we show that the forced dynamic dewetting of surfactant solutions depends sensitively on the surfactant concentration. To measure this effect, a hydrophobic rotating cylinder was horizontally half immersed in aqueous surfactant solutions. Dynamic contact angles were measured optically by extrapolating the contour of the meniscus to the contact line. Anionic (sodium 1-decanesulfonate, S-1DeS), cationic (cetyl trimethylammonium bromide, CTAB) and nonionic surfactants (C 4 E 1 , C 8 E 3 and C 12 E 5 ) with critical micelle concentrations (CMCs) spanning four orders of magnitude were used. The receding contact angle in water decreased with increasing velocity. This decrease was strongly enhanced when adding surfactant, even at surfactant concentrations of 10% of the critical micelle concentration. Plots of the receding contact angle-versus-velocity almost superimpose when being plotted at the same relative concentration (concentration/CMC). Thus the rescaled concentration is the dominating property for dynamic dewetting. The charge of the surfactants did not play a role, thus excluding electrostatic effects. The change in contact angle can be interpreted by local surface tension gradients, i.e. Marangoni stresses, close to the three-phase contact line. The decrease of dynamic contact angles with velocity follows two regimes. Despite the existence of Marangoni stresses close to the contact line, for a dewetting velocity above 1-10 mm s -1 the hydrodynamic theory is able to describe the experimental results for all surfactant concentrations. At slower velocities an additional steep decrease of the contact angle with velocity was observed. Particle tracking velocimetry showed that the flow profiles do not differ with and without surfactant on a scales >100 μm.

Dimeric Surfactants: Promising Ingredients of Cosmetics and Toiletries

Directory of Open Access Journals (Sweden)

Naveen Kumar

2013-11-01

Full Text Available Surfactants are an essential ingredient for cosmetic, toiletries and personal care products for enhancing their performance. Dimeric surfactants demonstrate superiority compared to conventional surfactants in all areas of application. Dimeric surfactants are extremely promising for utilization in various cosmetic formulations viz. shampoo, lotions, creams, conditioners etc. These surfactants possess extremely unique surface properties viz. lower surface tension, unique micellization, low critical micelle concentration (CMC and antimicrobial activity, higher solubilization etc. Dimerics enhance the performances of cosmetics in an extraordinary manner and provide eco-friendly preparations for human epidermis.

Structural study of surfactant-dependent interaction with protein

Energy Technology Data Exchange (ETDEWEB)

Mehan, Sumit; Aswal, Vinod K., E-mail: vkaswal@barc.gov.in [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Kohlbrecher, Joachim [Laboratory for Neutron Scattering, Paul Scherrer Institut, CH-5232 PSI Villigen (Switzerland)

2015-06-24

Small-angle neutron scattering (SANS) has been used to study the complex structure of anionic BSA protein with three different (cationic DTAB, anionic SDS and non-ionic C12E10) surfactants. These systems form very different surfactant-dependent complexes. We show that the structure of protein-surfactant complex is initiated by the site-specific electrostatic interaction between the components, followed by the hydrophobic interaction at high surfactant concentrations. It is also found that hydrophobic interaction is preferred over the electrostatic interaction in deciding the resultant structure of protein-surfactant complexes.

Effect of double-tailed surfactant architecture on the conformation, self-assembly, and processing in polypeptide-surfactant complexes.

Science.gov (United States)

Junnila, Susanna; Hanski, Sirkku; Oakley, Richard J; Nummelin, Sami; Ruokolainen, Janne; Faul, Charl F J; Ikkala, Olli

2009-10-12

This work describes the solid-state conformational and structural properties of self-assembled polypeptide-surfactant complexes with double-tailed surfactants. Poly(L-lysine) was complexed with three dialkyl esters of phosphoric acid (i.e., phosphodiester surfactants), where the surfactant tail branching and length was varied to tune the supramolecular architecture in a facile way. After complexation with the branched surfactant bis(2-ethylhexyl) phosphate in an aqueous solution, the polypeptide chains adopted an alpha-helical conformation. These rod-like helices self-assembled into cylindrical phases with the amorphous alkyl tails pointing outward. In complexes with dioctyl phosphate and didodecyl phosphate, which have two linear n-octyl or n-dodecyl tails, respectively, the polypeptide formed antiparallel beta-sheets separated by alkyl layers, resulting in well-ordered lamellar self-assemblies. By heating, it was possible to trigger a partial opening of the beta-sheets and disruption of the lamellar phase. After repeated heating/cooling, all of these complexes also showed a glass transition between 37 and 50 degrees C. Organic solvent treatment and plasticization by overstoichiometric amount of surfactant led to structure modification in poly(L-lysine)-dioctyl phosphate complexes, PLL(diC8)(x) (x = 1.0-3.0). Here, the alpha-helical PLL is surrounded by the surfactants and these bottle-brush-like chains self-assemble in a hexagonal cylindrical morphology. As x is increased, the materials are clearly plasticized and the degree of ordering is improved: The stiff alpha-helical backbones in a softened surfactant matrix give rise to thermotropic liquid-crystalline phases. The complexes were examined by Fourier transform infrared spectroscopy, small- and wide-angle X-ray scattering, transmission electron microscopy, differential scanning calorimetry, polarized optical microscopy, and circular dichroism.

The Biophysical Function of Pulmonary Surfactant

OpenAIRE

Rugonyi, Sandra; Biswas, Samares C.; Hall, Stephen B.

2008-01-01

Pulmonary surfactant lowers surface tension in the lungs. Physiological studies indicate two key aspects of this function: that the surfactant film forms rapidly; and that when compressed by the shrinking alveolar area during exhalation, the film reduces surface tension to very low values. These observations suggest that surfactant vesicles adsorb quickly, and that during compression, the adsorbed film resists the tendency to collapse from the interface to form a three-dimensional bulk phase....

ADSORPTION OF SURFACTANT ON CLAYS

Science.gov (United States)

Surfactants used to enhance remediation of soils by soil washing are often lost in the process. Neither the amount nor the cause of this loss is known. It is assumed that clays present in the soil are responsible for the loss of the surfactant. In this papere, adsorption prope...

Splash Dynamics of Falling Surfactant-Laden Droplets

Science.gov (United States)

Sulaiman, Nur; Buitrago, Lewis; Pereyra, Eduardo

2017-11-01

Splashing dynamics is a common issue in oil and gas separation technology. In this study, droplet impact of various surfactant concentrations onto solid and liquid surfaces is studied experimentally using a high-speed imaging analysis. Although this area has been widely studied in the past, there is still not a good understanding of the role of surfactant over droplet impact and characterization of resulting splash dynamics. The experiments are conducted using tap water laden with anionic surfactant. The effects of system parameters on a single droplet impingement such as surfactant concentration (no surfactant, below, at and above critical micelle concentration), parent drop diameter (2-5mm), impact velocity and type of impact surface (thin and deep pool) are investigated. Image analysis technique is shown to be an effective technique for identification of coalescence to splashing transition. In addition, daughter droplets size distributions are analyzed qualitatively in the events of splashing. As expected, it is observed that the formation of secondary droplets is affected by the surfactant concentration. A summary of findings will be discussed.

Recovering hydrocarbons with surfactants from lignin

Energy Technology Data Exchange (ETDEWEB)

Naae, D.G.; Whittington, L.E.; Ledoux, W.A.; Debons, F.E.

1988-11-29

This patent describes a method of recovering hydrocarbons from an underground hydrocarbon formation penetrated by at least one injection well and at least one production well, which comprises: injecting into the formation through an injection well a surfactant slug comprising about 0.1% to about 10% by weight of surfactants produced from lignin, the surfactants produced by placing lignin in contact with water, converting the lignin into low molecular weight lignin phenols by reducing the lignin in the presence of a reducing agent of carbon monoxide or hydrogen creating a reduction reaction mixture comprising oil soluble lignin phenols, the reduction occurring at a temperature greater than about 200/sup 0/C and a pressure greater than about 100 psi, recovering the oil soluble lignin phenols from the reduction mixture, and converting the lignin phenols into lignin surfactants by a reaction selected from the group consisting of alkoxylation, sulfonation, sulfation, aklylation, sulfomethylation, and alkoxysulfation; injecting into the formation through the injection well a drive fluid to push the surfactant slug towards a production well; and recovering hydrocarbons at the production well.

Influence of metacide - surfactant complexes on agricultural crops

Directory of Open Access Journals (Sweden)

Orynkul Esimova

2014-12-01

Full Text Available The complexes based on surfactants and polyhexamethyleneguanidine hydrochloride (metacide are important for agriculture. This paper considers compositions of known bactericidal metacide with different surfactants: anionic surfactant sodium dodecylsulphate (DDSNa and nonionic surfactant Tween 80 (monooleate of oxyethylenated anhydrosorbitols. The effect of individual components and associates of metacide and surfactants on productivity and infection of cereals was studied. According to the study, the highest productivity and infection rate were shown by the associate of metacide and Tween-80. At concentration of Tween-80 in aqueous solution equal to 0.001% in combination with metacide, efficiency was 98% at 0% infection. The surface tension and the wetting of metacide, DDSNa, Tween-80, and associates of metacide with surfactants were studied. In comparison with individual components, metacide-DDSNa and metacide-Tween-80 associates have higher surface activity.

Physicochemical characteristics of PFC surfactants for dry decontamination

Energy Technology Data Exchange (ETDEWEB)

Oh, Won Jin; Lee, Chi Woo [Korea University, Seoul (Korea)

2001-04-01

Even the trace amount of the used nuclear fuels of high radioactivity are hazardous to the earth and humans. Perfluorocarbons and perfluorocarbon surfactants are emerging to be efficient chemicals in the dry decontamination process of the used fuels of high radioactivity. The theme was undertaken to increase the knowledge on perfluorocarbon surfactants to develop the perfluorocarbon system in the dry decontamination process in Korea. Several cationic and anionic pfc surfactants were synthesized. Effects of pfc surfactants on electrochemical etching of silicon were investigated to form porous silicons. Forces were measured between silicon surfaces and AFM tip in the absence and presence of pfc surfactants. 7 refs., 10 figs. (Author)

Tunable, antibacterial activity of silicone polyether surfactants.

Science.gov (United States)

Khan, Madiha F; Zepeda-Velazquez, Laura; Brook, Michael A

2015-08-01

Silicone surfactants are used in a variety of applications, however, limited data is available on the relationship between surfactant structure and biological activity. A series of seven nonionic, silicone polyether surfactants with known structures was tested for in vitro antibacterial activity against Escherichia coli BL21. The compounds varied in their hydrophobic head, comprised of branched silicone structures with 3-10 siloxane linkages and, in two cases, phenyl substitution, and hydrophilic tail of 8-44 poly(ethylene glycol) units. The surfactants were tested at three concentrations: below, at, and above their Critical Micelle Concentrations (CMC) against 5 concentrations of E. coli BL21 in a three-step assay comprised of a 14-24h turbidometric screen, a live-dead stain and viable colony counts. The bacterial concentration had little effect on antibacterial activity. For most of the surfactants, antibacterial activity was higher at concentrations above the CMC. Surfactants with smaller silicone head groups had as much as 4 times the bioactivity of surfactants with larger groups, with the smallest hydrophobe exhibiting potency equivalent to sodium dodecyl sulfate (SDS). Smaller PEG chains were similarly associated with higher potency. These data link lower micelle stability and enhanced permeability of smaller silicone head groups to antibacterial activity. The results demonstrate that simple manipulation of nonionic silicone polyether structure leads to significant changes in antibacterial activity. Copyright © 2015 Elsevier B.V. All rights reserved.

Use of surfactants for the remediation of contaminated soils: A review

International Nuclear Information System (INIS)

Mao, Xuhui; Jiang, Rui; Xiao, Wei; Yu, Jiaguo

2015-01-01

Highlights: • The recent advances in use of surfactant for soil remediation are reviewed. • The mechanisms of surfactant-based soil remediation are discussed. • A review on the application of different types of surfactants is made. • The future research direction of surfactant-based technologies is suggested. - Abstract: Due to the great harm caused by soil contamination, there is an increasing interest to apply surfactants to the remediation of a variety of contaminated soils worldwide. This review article summarizes the findings of recent literatures regarding remediation of contaminated soils/sites using surfactants as an enhancing agent. For the surfactant-based remedial technologies, the adsorption behaviors of surfactants onto soil, the solubilizing capability of surfactants, and the toxicity and biocompatibility of surfactants are important considerations. Surfactants can enhance desorption of pollutants from soil, and promote bioremediation of organics by increasing bioavailability of pollutants. The removal of heavy metals and radionuclides from soils involves the mechanisms of dissolution, surfactant-associated complexation, and ionic exchange. In addition to the conventional ionic and nonionic surfactants, gemini surfactants and biosurfactants are also applied to soil remediation due to their benign features like lower critical micelle concentration (CMC) values and better biocompatibility. Mixed surfactant systems and combined use of surfactants with other additives are often adopted to improve the overall performance of soil washing solution for decontamination. Worldwide the field studies and full-scale remediation using surfactant-based technologies are yet limited, however, the already known cases reveal the good prospect of applying surfactant-based technologies to soil remediation

Use of surfactants for the remediation of contaminated soils: A review

Energy Technology Data Exchange (ETDEWEB)

Mao, Xuhui, E-mail: clab@whu.edu.cn [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); Jiang, Rui; Xiao, Wei [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); Yu, Jiaguo, E-mail: jiaguoyu@yahoo.com [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China)

2015-03-21

Highlights: • The recent advances in use of surfactant for soil remediation are reviewed. • The mechanisms of surfactant-based soil remediation are discussed. • A review on the application of different types of surfactants is made. • The future research direction of surfactant-based technologies is suggested. - Abstract: Due to the great harm caused by soil contamination, there is an increasing interest to apply surfactants to the remediation of a variety of contaminated soils worldwide. This review article summarizes the findings of recent literatures regarding remediation of contaminated soils/sites using surfactants as an enhancing agent. For the surfactant-based remedial technologies, the adsorption behaviors of surfactants onto soil, the solubilizing capability of surfactants, and the toxicity and biocompatibility of surfactants are important considerations. Surfactants can enhance desorption of pollutants from soil, and promote bioremediation of organics by increasing bioavailability of pollutants. The removal of heavy metals and radionuclides from soils involves the mechanisms of dissolution, surfactant-associated complexation, and ionic exchange. In addition to the conventional ionic and nonionic surfactants, gemini surfactants and biosurfactants are also applied to soil remediation due to their benign features like lower critical micelle concentration (CMC) values and better biocompatibility. Mixed surfactant systems and combined use of surfactants with other additives are often adopted to improve the overall performance of soil washing solution for decontamination. Worldwide the field studies and full-scale remediation using surfactant-based technologies are yet limited, however, the already known cases reveal the good prospect of applying surfactant-based technologies to soil remediation.

Materials Synthesis Of Barium Hexa ferrite Used Local Natural Resources

International Nuclear Information System (INIS)

Ridwan; Sulungbudi, Grace Tj.; Mujamilah

2003-01-01

The magnetic materials of barium hexa ferrites, Ba O.6Fe 2 O 3 successfully synthesized by powder metallurgy method used local natural resources from materials waste of steel fabrication (HSM, CRM), waste of polymer fabrication (LK) as well as iron sands (PBA). These waste as well as iron sands were the main resources of iron oxide, Fe 2 O 3 . The barium oxide used in this experiments are from BaCO 3 product of Merck, and BaCO 4 which is commercially available in the market as barite. Phase identification by x-ray diffraction technique show the synthesized magnetic materials are agreed with the available commercial product, (SUMI). The energy product maximum (BH) max measured by vibrating sample magnetometer (VSM) for the samples used HSM-, CRM- and BaCO 3 as basic materials are 1.141 MGOe and 1.136 MGOe while SUMI is 1.142 MGOe. However for the samples made from LK-, PBA- used of BaCO 3 or CRM- with barite, the energy product maximum (BH) max are relatively lower than commercial product

Targeted disruption of the Hexa gene results in mice with biochemical and pathologic features of Tay-Sachs disease

Energy Technology Data Exchange (ETDEWEB)

Proia, R.L.; Yamanaka, S.; Johnson, M.D. [and others

1994-09-01

Tay-Sachs disease, the prototype of the G{sub M2} gangliosidoses, is a catastrophic neurodegenerative disorder of infancy. The disease is caused by mutations in the HEXA gene resulting in an absence of the lysosomal enzyme, {beta}-hexosaminidase A. As consequence of the enzyme deficiency, G{sub M2} ganglioside accumulates progressively, beginning early in fetal life, to excessive amounts in the central nervous system (CNS). Rapid mental and motor deterioration starting in the first year of life leads to death by 2 to 4 years of age. Through the targeted disruption of the Hexa gene in embryonic stem cells, we have produced mice with biochemical and neuropathologic features of Tay-Sachs disease. The mutant mice exhibited less than 1% of normal {beta}-hexosaminidase A activity and accumulated G{sub M2} ganglioside in their CNS in an age-dependent manner. The accumulated ganglioside was stored in neurons as membranous cytoplasmic bodies characteristically found in the neurons of Tay-Sachs disease patients. At three to five months of age the mutant mice showed no apparent defects in motor or memory function. These {beta}-hexosaminidase A deficient mice should be useful for devising strategies to introduce functional enzymes and genes into the CNS. This model may also be valuable for studying the biochemical and pathologic changes occurring during the course of the disease.

Structure of sodium alkyl sulphate micelles

International Nuclear Information System (INIS)

Vass, Sz.

1990-05-01

Micellar aggregation numbers of aggregated sodium octyl, decyl, dodecyl and tetradecyl sulphate molecules obtained from small-angle neutron scattering (SANS) measurements are reported. The surfactant concentration and solution temperature were varied systematically. A survey of the physical models and evaluation algorithms applied for SANS are presented. By utilizing a new least square fitting algorithm, the formation and annihilation parameters of orthopositronium in the micellar pseudophase and in the aqueous solvent is deduced by evaluating positron lifetime spectra measured by conventional technqiues. (R.P.) 157 refs.; 10 figs

Surfactant-Polymer Interaction for Improved Oil Recovery; FINAL

International Nuclear Information System (INIS)

Gabitto, Jorge; Mohanty, Kishore K.

2002-01-01

The goal of this research was to use the interaction between a surfactant and a polymer for efficient displacement of tertiary oil by improving slug integrity, oil solubility in the displacing fluid and mobility control. Surfactant-polymer flooding has been shown to be highly effective in laboratory-scale linear floods. The focus of this proposal is to design an inexpensive surfactant-polymer mixture that can efficiently recover tertiary oil by avoiding surfactant slug degradation and viscous/heterogeneity fingering

Surfactant properties of human meibomian lipids.

Science.gov (United States)

Mudgil, Poonam; Millar, Thomas J

2011-03-25

Human meibomian lipids are the major part of the lipid layer of the tear film. Their surfactant properties enable their spread across the aqueous layer and help maintain a stable tear film. The purpose of this study was to investigate surfactant properties of human meibomian lipids in vitro and to determine effects of different physical conditions such as temperature and increased osmolarity, such as occur in dry eye, on these properties. Human meibomian lipids were spread on an artificial tear solution in a Langmuir trough. The lipid films were compressed and expanded to record the surface pressure-area (Π-A) isocycles. The isocycles were recorded under different physical conditions such as high pressure, increasing concentration and size of divalent cations, increasing osmolarity, and varying temperature. Π-A isocycles of meibomian lipids showed that they form liquid films that are compressible and multilayered. The isocycles were unaffected by increasing concentration or size of divalent cations and increasing osmolarity in the subphase. Temperature had a marked effect on the lipids. Increase in temperature caused lipid films to become fluid, an expected feature, but decrease in temperature unexpectedly caused expansion of lipids and an increase in pressure suggesting enhanced surfactant properties. Human meibomian lipids form highly compressible, non-collapsible, multilayered liquid films. These lipids have surfactants that allow them to spread across an aqueous subphase. Their surfactant properties are unaffected by increasing divalent cations or hyperosmolarity but are sensitive to temperature. Cooling of meibomian lipids enhances their surfactant properties.

Surfactant selection for a liquid foam-bed photobioreactor.

Science.gov (United States)

Janoska, Agnes; Vázquez, María; Janssen, Marcel; Wijffels, René H; Cuaresma, María; Vílchez, Carlos

2018-02-01

A novel liquid foam-bed photobioreactor has been shown to hold potential as an innovative technology for microalgae production. In this study, a foam stabilizing agent has been selected which fits the requirements of use in a liquid foam-bed photobioreactor. Four criteria were used for an optimal surfactant: the surfactant should have good foaming properties, should not be rapidly biodegradable, should drag up microalgae in the foam formed, and it should not be toxic for microalgae. Ten different surfactants (nonionic, cationic, and anionic) and two microalgae genera (Chlorella and Scenedesmus) were compared on the above-mentioned criteria. The comparison showed the following facts. Firstly, poloxameric surfactants (Pluronic F68 and Pluronic P84) have acceptable foaming properties described by intermediate foam stability and liquid holdup and small bubble size. Secondly, the natural surfactants (BSA and Saponin) and Tween 20 were easily biodegraded by bacteria within 3 days. Thirdly, for all surfactants tested the microalgae concentration is reduced in the foam phase compared to the liquid phase with exception of the cationic surfactant CTAB. Lastly, only BSA, Saponin, Tween 20, and the two Pluronics were not toxic at concentrations of 10 CMC or higher. The findings of this study indicate that the Pluronics (F68 and P84) are the best surfactants regarding the above-mentioned criteria. Since Pluronic F68 performed slightly better, this surfactant is recommended for application in a liquid foam-bed photobioreactor. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 2018. © 2018 American Institute of Chemical Engineers.

History of surfactant up to 1980.

Science.gov (United States)

Obladen, Michael

2005-01-01

Remarkable insight into disturbed lung mechanics of preterm infants was gained in the 18th and 19th century by the founders of obstetrics and neonatology who not only observed respiratory failure but also designed devices to treat it. Surfactant research followed a splendid and largely logical growth curve. Pathological changes in the immature lung were characterized in Germany by Virchow in 1854 and by Hochheim in 1903. The Swiss physiologist von Neergard fully understood surfactant function in 1929, but his paper was ignored for 25 years. The physical properties of surfactant were recognized in the early 1950s from research on warfare chemicals by Pattle in Britain and by Radford and Clements in the United States. The causal relationship of respiratory distress syndrome (RDS) and surfactant deficiency was established in the USA by Avery and Mead in 1959. The Australian obstetrician Liggins induced lung maturity with glucocorticoids in 1972, but his discovery was not fully believed for another 20 years. A century of basic research was rewarded when Fujiwara introduced surfactant substitution in Japan in 1980 for treatment and prevention of RDS. Copyright 2005 S. Karger AG, Basel

Adsorption of anionic surfactants in limestone medium during oil recovery

Energy Technology Data Exchange (ETDEWEB)

Canbolat, Serhat; Bagci, Suat [Middle East Technical Univ., Dept. of Petroleum and Natural Gas Engineering, Ankara (Turkey)

2004-07-15

Foam-forming surfactant performance was evaluated by several experimental methods (interfacial tension, foam stability, corefloods) using commercial surfactants. There is considerable interest in the use of foam-forming surfactants for mobility control in water flood. To provide effective mobility control, the injected surfactant must propagate from the injection well toward the production well. One of the important parameters affecting propagation of foam-forming surfactant through the reservoir is the retention of surfactant due to its adsorption on reservoir rock. The determination of the adsorption of foam-forming surfactants in limestone reservoirs is important for the residual oil recovery efficiency. Adsorption measurements, recovery efficiencies, and surfactant and alkaline flooding experiments carried out with the representative of the selected surfactants alkaline solutions, linear alkyl benzene sulphonic acid (LABSA), sodium lauryl ether sulfate (SLES), and NaOH in a limestone medium. These surfactants were selected with respect to their foaming ability. Calibration curves formed by pH measurements were used to determine the correct adsorption amount of the used surfactants and recovery efficiency of these surfactants compared with base waterflooding. The results showed that LABSA adsorbed more than SLES in limestone reservoirs. The recovery efficiency of SLES was higher than the recovery efficiency of LABSA, and they decreased the recovery efficiency with respect to only the water injection case. (Author)

In vitro erythemal UV-A protection factors of inorganic sunscreens distributed in aqueous media using carnauba wax-decyl oleate nanoparticles.

Science.gov (United States)

Villalobos-Hernández, J R; Müller-Goymann, C C

2007-01-01

This paper describes the in vitro photoprotection in the UV-A range, i.e. 320-400 nm obtained by the use of carnauba wax-decyl oleate nanoparticles either as encapsulation systems or as accompanying vehicles for inorganic sunscreens such as barium sulfate, strontium carbonate and titanium dioxide. Lipid-free inorganic sunscreen nanosuspensions, inorganic sunscreen-free wax-oil nanoparticle suspensions and wax-oil nanoparticle suspensions containing inorganic sunscreens dispersed either in their oil phase or their aqueous phase were prepared by high pressure homogenization. The in vitro erythemal UV-A protection factors (EUV-A PFs) of the nanosuspensions were calculated by means of a sun protection analyzer. EUV-A PFs being no higher than 4 were obtained by the encapsulation of barium sulfate and strontium carbonate, meanwhile by the distribution of titanium dioxide in presence of wax-oil nanoparticles, the EUV-A PFs varied between 2 and 19. The increase in the EUV-A PFs of the titanium dioxide obtained by the use of wax-oil nanoparticles demonstrated a better performance of the sun protection properties of this pigment in the UV-A region.

Use of surfactants for the remediation of contaminated soils: a review.

Science.gov (United States)

Mao, Xuhui; Jiang, Rui; Xiao, Wei; Yu, Jiaguo

2015-03-21

Due to the great harm caused by soil contamination, there is an increasing interest to apply surfactants to the remediation of a variety of contaminated soils worldwide. This review article summarizes the findings of recent literatures regarding remediation of contaminated soils/sites using surfactants as an enhancing agent. For the surfactant-based remedial technologies, the adsorption behaviors of surfactants onto soil, the solubilizing capability of surfactants, and the toxicity and biocompatibility of surfactants are important considerations. Surfactants can enhance desorption of pollutants from soil, and promote bioremediation of organics by increasing bioavailability of pollutants. The removal of heavy metals and radionuclides from soils involves the mechanisms of dissolution, surfactant-associated complexation, and ionic exchange. In addition to the conventional ionic and nonionic surfactants, gemini surfactants and biosurfactants are also applied to soil remediation due to their benign features like lower critical micelle concentration (CMC) values and better biocompatibility. Mixed surfactant systems and combined use of surfactants with other additives are often adopted to improve the overall performance of soil washing solution for decontamination. Worldwide the field studies and full-scale remediation using surfactant-based technologies are yet limited, however, the already known cases reveal the good prospect of applying surfactant-based technologies to soil remediation. Copyright © 2014 Elsevier B.V. All rights reserved.

Silica micro- and nanoparticles reduce the toxicity of surfactant solutions.

Science.gov (United States)

Ríos, Francisco; Fernández-Arteaga, Alejandro; Fernández-Serrano, Mercedes; Jurado, Encarnación; Lechuga, Manuela

2018-04-20

In this work, the toxicity of hydrophilic fumed silica micro- and nanoparticles of various sizes (7 nm, 12 nm, and 50 μm) was evaluated using the luminescent bacteria Vibrio fischeri. In addition, the toxicity of an anionic surfactant solution (ether carboxylic acid), a nonionic surfactant solution (alkyl polyglucoside), and a binary (1:1) mixture of these solutions all containing these silica particles was evaluated. Furthermore, this work discusses the adsorption of surfactants onto particle surfaces and evaluates the effects of silica particles on the surface tension and critical micellar concentration (CMC) of these anionic and nonionic surfactants. It was determined that silica particles can be considered as non-toxic and that silica particles reduce the toxicity of surfactant solutions. Nevertheless, the toxicity reduction depends on the ionic character of the surfactants. Differences can be explained by the different adsorption behavior of surfactants onto the particle surface, which is weaker for nonionic surfactants than for anionic surfactants. Regarding the effects on surface tension, it was found that silica particles increased the surface activity of anionic surfactants and considerably reduced their CMC, whereas in the case of nonionic surfactants, the effects were reversed. Copyright © 2018 Elsevier B.V. All rights reserved.

Synergism and Physicochemical Properties of Anionic/Amphoteric Surfactant Mixtures with Nonionic Surfactant of Amine Oxide Type

Science.gov (United States)

Blagojević, S. M.; Pejić, N. D.; Blagojević, S. N.

2017-12-01

The physicochemical properties of initial formulation, that is anionic/amphoteric surfactants mixture SLES/AOS/CAB (sodium lauryl ether sulfate (SLES), α-olefin sulfonates (AOS) and cocamidopropyl betaine (CAB) at ratio 80 : 15 : 5) with nonionic surfactant of amine oxide type (lauramine oxide (AO)) in various concentration (1-5%) were studied. To characterize the surfactants mixture, the critical micelle concentration (CMC), surface tension (γ), foam volume, biodegradability and irritability were determined. This study showed that adding of AO in those mixtures lowered both γ and CMC as well as enhanced SLES/AOS/CAB foaming properties, but did not significantly affect biodegradability and irritability of initial formulation. Moreover, an increase in AO concentration has a meaningful synergistic effect on the initial formulation properties. All those results indicates that a nonionic surfactant of amine oxide type significantly improves the performance of anionic/amphoteric mixed micelle systems, and because of that anionic/amphoteric/nonionic mixture can be used in considerably lower concentrations as a cleaning formulation.

Surfactant therapy in late preterm infants

Directory of Open Access Journals (Sweden)

Murat Yurdakök

2013-06-01

Full Text Available Late preterm (LPT neonates are at a high risk for respiratory distress soon after birth due to respiratory distress syndrome (RDS, transient tachypnea of the newborn, persistent pulmonary hypertension, and pneumonia along with an increased need for surfactant replacement therapy, continuous positive airway pressure, and ventilator support when compared with the term neonates. In the past, studies on outcomes of infants with respiratory distress have primarily focused on extremely premature infants, leading to a gap in knowledge and understanding of the developmental biology and mechanism of pulmonary diseases in LPT neonates. Surfactant deficiency is the most frequent etiology of RDS in very preterm and moderately preterm infants, while cesarean section and lung infection play major roles in RDS development in LPT infants. The clinical presentation and the response to surfactant therapy in LPT infants may be different than that seen in very preterm infants. Incidence of pneumonia and occurrence of pneumothorax are significantly higher in LPT and term infants. High rates of pneumonia in these infants may result in direct injury to the type II alveolar cells of the lung with decreasing synthesis, release, and processing of surfactant. Increased permeability of the alveolar capillary membrane to both fluid and solutes is known to result in entry of plasma proteins into the alveolar hypophase, further inhibiting the surface properties of surfactant. However, the oxygenation index value do not change dramatically after ventilation or surfactant administration in LPT infants with RDS compared to very preterm infants. These finding may indicate a different pathogenesis of RDS in late preterm and term infants. In conclusion, surfactant therapy may be of significant benefit in LPT infants with serious respiratory failure secondary to a number of insults. However, optimal timing and dose of administration are not so clear in this group. Additional

Charging and Screening in Nonpolar Solutions of Nonionizable Surfactants

Science.gov (United States)

Behrens, Sven

2010-03-01

Nonpolar liquids do not easily accommodate electric charges, but surfactant additives are often found to dramatically increase the solution conductivity and promote surface charging of suspended colloid particles. Such surfactant-mediated electrostatic effects have been associated with equilibrium charge fluctuations among reverse surfactant micelles and in some cases with the statistically rare ionization of individual surfactant molecules. Here we present experimental evidence that even surfactants without any ionizable group can mediate charging and charge screening in nonpolar oils, and that they can do so at surfactant concentrations well below the critical micelle concentration (cmc). Precision conductometry, light scattering, and Karl-Fischer titration of sorbitan oleate solutions in hexane, paired with electrophoretic mobility measurements on suspended polymer particles, reveal a distinctly electrostatic action of the surfactant. We interpret our observations in terms of a charge fluctuation model and argue that the observed charging processes are likely facilitated, but not limited, by the presence of ionizable impurities.

Is surfactant a promising additive drug in ALI/ARDS-patients?

NARCIS (Netherlands)

Schultz, MJ; Kesecioglu, J

The rationale for surfactant replacement therapy in patients with acute respiratory distress syndrome (ARDS) is to restore the normal composition of the surfactant system, as well as to overcome ongoing inactivation of present surfactant. Indeed, surfactant replacement therapy call normalize the

Is surfactant a promising additive drug in ALI/ARDS-patients?

NARCIS (Netherlands)

Schultz, Marcus J.; Kesecioglu, Jozef

2004-01-01

The rationale for surfactant replacement therapy in patients with acute respiratory distress syndrome (ARDS) is to restore the normal composition of the surfactant system, as well as to overcome ongoing inactivation of present surfactant. Indeed, surfactant replacement therapy call normalize the

Maintained inspiratory activity during proportional assist ventilation in surfactant-depleted cats early after surfactant instillation: phrenic nerve and pulmonary stretch receptor activity

Directory of Open Access Journals (Sweden)

Schaller Peter

2006-03-01

Full Text Available Abstract Background Inspiratory activity is a prerequisite for successful application of patient triggered ventilation such as proportional assist ventilation (PAV. It has recently been reported that surfactant instillation increases the activity of slowly adapting pulmonary stretch receptors (PSRs followed by a shorter inspiratory time (Sindelar et al, J Appl Physiol, 2005 [Epub ahead of print]. Changes in lung mechanics, as observed in preterm infants with respiratory distress syndrome and after surfactant treatment, might therefore influence the inspiratory activity when applying PAV early after surfactant treatment. Objective To investigate the regulation of breathing and ventilatory response in surfactant-depleted young cats during PAV and during continuous positive airway pressure (CPAP early after surfactant instillation in relation to phrenic nerve activity (PNA and the activity of PSRs. Methods Seven anesthetized, endotracheally intubated young cats were exposed to periods of CPAP and PAV with the same end-expiratory pressure (0.2–0.5 kPa before and after lung lavage and after surfactant instillation. PAV was set to compensate for 75% of the lung elastic recoil. Results Tidal volume and respiratory rate were higher with lower PaCO2 and higher PaO2 during PAV than during CPAP both before and after surfactant instillation (p Conclusion PSR activity and the control of breathing are maintained during PAV in surfactant-depleted cats early after surfactant instillation, with a higher ventilatory response and a lower breathing effort than during CPAP.

Ecotoxicological characterization of polyoxyethylene glycerol ester non-ionic surfactants and their mixtures with anionic and non-ionic surfactants.

Science.gov (United States)

Ríos, Francisco; Fernández-Arteaga, Alejandro; Lechuga, Manuela; Fernández-Serrano, Mercedes

2017-04-01

This paper reports on a study that investigated the aquatic toxicity of new non-ionic surfactants derived from renewable raw materials, polyoxyethylene glycerol ester (PGE), and their binary mixtures with anionic and non-ionic surfactants. Toxicity of pure PGEs was determined using representative organisms from different trophic levels: luminescent bacteria (Vibrio fischeri), microalgae (Pseudokirchneriella subcapitata), and freshwater crustaceans (Daphnia magna). Relationships between toxicity and the structural parameters such as unit of ethylene oxide (EO) and hydrophilic-lipophilic balance (HLB) were evaluated. Critical micellar concentration (CMC) in the conditions of the toxicity test was also determined. It was found that the toxicity of the aqueous solutions of PGE decreased when the number of EO units in the molecule, HLB, and CMC increased. PGEs showed lower CMC in marine medium, and the toxicity to V. ficheri is lower when the CMC was higher. Given their non-polar nature, narcosis was expected to be the primary mode of toxic action of PGEs. For the mixture of surfactants, we observed that the mixtures with PGE that had the higher numbers of EO units were more toxic than the aqueous solutions of pure surfactants. Moreover, we found that concentration addition was the type of action more likely to occur for mixtures of PGE with lower numbers of EO units with non-ionic surfactants (alkylpolyglucoside and fatty alcohol ethoxylate), whereas for the mixture of PGE with lower EO units and anionic surfactant (ether carboxylic derivative), the most common response type was response addition. In case of mixtures involving amphoteric surfactants and PGEs with the higher numbers of EO units, no clear pattern with regard to the mixture toxicity response type could be observed.

Synthesis and properties evaluation of sulfobetaine surfactant with double hydroxyl

Science.gov (United States)

Zhou, Ming; Luo, Gang; Zhang, Ze; Li, Sisi; Wang, Chengwen

2017-09-01

A series of sulfobetaine surfactants {N-[(3-alkoxy-2-hydroxyl)propoxy] ethyl-N,N-dimethyl-N-(2-hydroxyl)propyl sulfonate} ammonium chloride were synthesized with raw materials containing linear saturated alcohol, N,N-dimethylethanolamine, sodium 3-chloro-2-hydroxyl propane sulfonic acid and epichlorohydrin. The molecule structures of sulfobetaine surfactants were characterized by FTIR, 1HNMR and elemental analysis. Surface tension measurements can provide us information about the surface tension at the CMC (γCMC), pC20, Γmax and Amin. The pC20 values of sulfobetaine surfactants increase with the hydrophobic chain length increasing. Amin values of the surfactants decrease with increasing hydrophobic chain length from 10 to 14. The critical micelle concentration (CMC) and surface tension (γCMC) values of the sulfobetaine surfactants decrease with increasing hydrophobic chain length from 10 to 16. The lipophilicity of surfactant was enhanced with the increase of the carbon chain, however, the ability of anti-hard water was weakened. The minimum oil/water interfacial tension of four kinds of sulfobetaine surfactants is 10-2-10-3 mN/m magnitude, which indicates that the synthesized bis-hydroxy sulfobetaine surfactants have a great ability to reduce interfacial tension in the surfactant flooding system. The surface tension (γCMC) values of synthesized surfactants were lower compared with conventional anionic surfactant sodium dodecyl sulfonate.

Surfactant treatment before first breath for respiratory distress syndrome in preterm lambs: comparison of a peptide-containing synthetic lung surfactant with porcine-derived surfactant

Directory of Open Access Journals (Sweden)

van Zyl JM

2013-08-01

Full Text Available Johann M van Zyl,1 Johan Smith2 1Division of Pharmacology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, South Africa; 2Department of Paediatrics and Child Health, Tygerberg Children's Hospital, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, South Africa Background: In a recent study utilizing a saline-lavaged adult rabbit model, we described a significant improvement in systemic oxygenation and pulmonary shunt after the instillation of a novel synthetic peptide-containing surfactant, Synsurf. Respiratory distress syndrome in the preterm lamb more closely resembles that of the human infant, as their blood gas, pH values, and lung mechanics deteriorate dramatically from birth despite ventilator support. Moreover, premature lambs have lungs which are mechanically unstable, with the advantage of being able to measure multiple variables over extended periods. Our objective in this study was to investigate if Synsurf leads to improved systemic oxygenation, lung mechanics, and histology in comparison to the commercially available porcine-derived lung surfactant Curosurf® when administered before first breath in a preterm lamb model. Materials and methods: A Cesarean section was performed under general anesthesia on 18 time-dated pregnant Dohne Merino ewes at 129–130 days gestation. The premature lambs were delivered and ventilated with an expiratory tidal volume of 6–8 mL/kg for the first 30 minutes and thereafter at 8–10 mL/kg. In a randomized controlled trial, the two surfactants tested were Synsurf and Curosurf®, both at a dose of 100 mg/kg phospholipids (1,2-dipalmitoyl-L-α-phosphatidylcholine; 90% in Synsurf, 40% in Curosurf®. A control group of animals was treated with normal saline. Measurements of physiological variables, blood gases, and lung mechanics were made before and after surfactant and saline replacement and at 15, 30, 45, 60, 90, 120, 180

Surfactant use with nitrate-based bioremediation

International Nuclear Information System (INIS)

Wilson, B.H.; Hutchins, S.R.; West, C.C.

1995-01-01

This study presents results of an initial survey on the effect of six surfactants on the biodegradation of petroleum hydrocarbons in bioremediation applications using nitrate as the electron acceptor. Aquifer material from Park City, Kansas, was used for the study. The three atomic surfactants chosen were Steol CS-330, Dowfax 8390 and sodium dodecylbenzene sulfonate (SDBS); the three nonionic surfactants were T-MAZ-60, Triton X-100, and Igepal CO-660. Both Steol CS-330 and T-MAZ-60 biodegraded under denitrifying conditions. The Steol inhibited biodegradation of benzene, toluene, ethylbenzene, xylenes, and trimethylbenzenes (BTEXTMB). Only toluene was rapidly degraded in the presence of T-MAZ-60. Biodegradation of all compounds, including toluene, appears to be inhibited by Dowfax 8390 and SDBS. No biodegradation of Dowfax 8390 or SDBS was observed. SDBS inhibited denitrification, but Dowfax 8390 did not. For the microcosms containing Triton X-100 or Igepal CO-660, removal of toluene, ethylbenzene, m-xylene, 1,3,5-TMB, and 1,2,4-TMB were similar to their removals in the no-surfactant treatment. These two surfactants did not biodegrade, did not inhibit biodegradation of the alkylbenzenes, and did not inhibit denitrification. Further studies are continuing with aquifer material from Eglin Air Force Base

Foaming behaviour of polymer-surfactant solutions

International Nuclear Information System (INIS)

Cervantes-MartInez, Alfredo; Maldonado, Amir

2007-01-01

We study the effect of a non-ionic amphiphilic polymer (PEG-100 stearate also called Myrj 59) on the foaming behaviour of aqueous solutions of an anionic surfactant (sodium dodecyl sulfate or SDS). The SDS concentration was kept fixed while the Myrj 59 concentration was varied. Measurements of foamability, surface tension and electrical conductivity were carried out. The results show two opposite effects depending on the polymer concentration: foamability is higher when the Myrj 59 concentration is low; however, it decreases considerably when the polymer concentration is increased. This behaviour is due to the polymer adsorption at the air/liquid interface at lower polymer concentrations, and to the formation of a polymer-surfactant complex in the bulk at higher concentrations. The results are confirmed by surface tension and electrical conductivity measurements, which are interpreted in terms of the microstructure of the polymer-surfactant solutions. The observed behaviour is due to the amphiphilic nature of the studied polymer. The increased hydrophobicity of Myrj 59, compared to that of water-soluble polymers like PEG or PEO, increases its 'reactivity' towards SDS, i.e. the strength of its interaction with this anionic surfactant. Our results show that hydrophobically modified polymers have potential applications as additives in order to control the foaming properties of surfactant solutions

Surfactant Sensors in Biotechnology; Part 1 – Electrochemical Sensors

Directory of Open Access Journals (Sweden)

Milan Sak-Bosnar

2004-01-01

Full Text Available An overview on electrochemical surfactant sensors is given with special attention to papers published since 1993. The importance of surfactants in modern biotechnology is stressed out. Electrochemical sensors are usually divided according to the measured physical quantity to potentiometric, amperometric, conductometric and impedimetric surfactant sensors. The last ones are very few. Potentiometric surfactant sensors are the most numerous due to their simplicity and versatility. They can be used either as end-point titration sensors or as direct EMF measurement sensors, in batch or flow-through mode. Some amperometric surfactant sensors are true biosensors that use microorganisms or living cells.

Generation of HEXA-deficient hiPSCs from fibroblasts of a Tay-Sachs disease patient

Directory of Open Access Journals (Sweden)

Zhong Liu

2016-09-01

Full Text Available Human iPSC line TSD-01-hiPSC was generated from fibroblasts of a patient with infantile Tay-Sachs disease (TSD. The patient is compound heterozygous at the HEXA gene by carrying a 1278insTATC allele and an IVS12+1G>C allele. STEMCCA lentivirus, which expresses OCT4, SOX2, KLF4, and c-MYC from a polycistronic transcript, were used for reprogramming. TSD-01-hiPSC express pluripotency markers such as OCT4, SOX2, NANOG, Tra-1-60, and alkaline phosphatase, and can differentiate into tissues from all the three embryonic germ layers. This TSD patient-derived hiPSC line may serve as a valuable in vitro tool for disease modeling and drug test.

A level-set method for two-phase flows with soluble surfactant

Science.gov (United States)

Xu, Jian-Jun; Shi, Weidong; Lai, Ming-Chih

2018-01-01

A level-set method is presented for solving two-phase flows with soluble surfactant. The Navier-Stokes equations are solved along with the bulk surfactant and the interfacial surfactant equations. In particular, the convection-diffusion equation for the bulk surfactant on the irregular moving domain is solved by using a level-set based diffusive-domain method. A conservation law for the total surfactant mass is derived, and a re-scaling procedure for the surfactant concentrations is proposed to compensate for the surfactant mass loss due to numerical diffusion. The whole numerical algorithm is easy for implementation. Several numerical simulations in 2D and 3D show the effects of surfactant solubility on drop dynamics under shear flow.

Regulatory network controlling extracellular proteins in Erwinia carotovora subsp. carotovora: FlhDC, the master regulator of flagellar genes, activates rsmB regulatory RNA production by affecting gacA and hexA (lrhA) expression.

Science.gov (United States)

Cui, Yaya; Chatterjee, Asita; Yang, Hailian; Chatterjee, Arun K

2008-07-01

Erwinia carotovora subsp. carotovora produces an array of extracellular proteins (i.e., exoproteins), including plant cell wall-degrading enzymes and Harpin, an effector responsible for eliciting hypersensitive reaction. Exoprotein genes are coregulated by the quorum-sensing signal, N-acyl homoserine lactone, plant signals, an assortment of transcriptional factors/regulators (GacS/A, ExpR1, ExpR2, KdgR, RpoS, HexA, and RsmC) and posttranscriptional regulators (RsmA, rsmB RNA). rsmB RNA production is positively regulated by GacS/A, a two-component system, and negatively regulated by HexA (PecT in Erwinia chrysanthemi; LrhA [LysR homolog A] in Escherichia coli) and RsmC, a putative transcriptional adaptor. While free RsmA, an RNA-binding protein, promotes decay of mRNAs of exoprotein genes, binding of RsmA with rsmB RNA neutralizes the RsmA effect. In the course of studies of GacA regulation, we discovered that a locus bearing strong homology to the flhDC operon of E. coli also controls extracellular enzyme production. A transposon insertion FlhDC(-) mutant produces very low levels of pectate lyase, polygalacturonase, cellulase, protease, and E. carotovora subsp. carotovora Harpin (Harpin(Ecc)) and is severely attenuated in its plant virulence. The production of these exoproteins is restored in the mutant carrying an FlhDC(+) plasmid. Sequence analysis and transcript assays disclosed that the flhD operon of E. carotovora subsp. carotovora, like those of other enterobacteria, consists of flhD and flhC. Complementation analysis revealed that the regulatory effect requires functions of both flhD and flhC products. The data presented here show that FlhDC positively regulates gacA, rsmC, and fliA and negatively regulates hexA (lrhA). Evidence shows that FlhDC controls extracellular protein production through cumulative effects on hexA and gacA. Reduced levels of GacA and elevated levels of HexA in the FlhDC(-) mutant are responsible for the inhibition of rsmB RNA

Regulatory Network Controlling Extracellular Proteins in Erwinia carotovora subsp. carotovora: FlhDC, the Master Regulator of Flagellar Genes, Activates rsmB Regulatory RNA Production by Affecting gacA and hexA (lrhA) Expression▿

Science.gov (United States)

Cui, Yaya; Chatterjee, Asita; Yang, Hailian; Chatterjee, Arun K.

2008-01-01

Erwinia carotovora subsp. carotovora produces an array of extracellular proteins (i.e., exoproteins), including plant cell wall-degrading enzymes and Harpin, an effector responsible for eliciting hypersensitive reaction. Exoprotein genes are coregulated by the quorum-sensing signal, N-acyl homoserine lactone, plant signals, an assortment of transcriptional factors/regulators (GacS/A, ExpR1, ExpR2, KdgR, RpoS, HexA, and RsmC) and posttranscriptional regulators (RsmA, rsmB RNA). rsmB RNA production is positively regulated by GacS/A, a two-component system, and negatively regulated by HexA (PecT in Erwinia chrysanthemi; LrhA [LysR homolog A] in Escherichia coli) and RsmC, a putative transcriptional adaptor. While free RsmA, an RNA-binding protein, promotes decay of mRNAs of exoprotein genes, binding of RsmA with rsmB RNA neutralizes the RsmA effect. In the course of studies of GacA regulation, we discovered that a locus bearing strong homology to the flhDC operon of E. coli also controls extracellular enzyme production. A transposon insertion FlhDC− mutant produces very low levels of pectate lyase, polygalacturonase, cellulase, protease, and E. carotovora subsp. carotovora Harpin (HarpinEcc) and is severely attenuated in its plant virulence. The production of these exoproteins is restored in the mutant carrying an FlhDC+ plasmid. Sequence analysis and transcript assays disclosed that the flhD operon of E. carotovora subsp. carotovora, like those of other enterobacteria, consists of flhD and flhC. Complementation analysis revealed that the regulatory effect requires functions of both flhD and flhC products. The data presented here show that FlhDC positively regulates gacA, rsmC, and fliA and negatively regulates hexA (lrhA). Evidence shows that FlhDC controls extracellular protein production through cumulative effects on hexA and gacA. Reduced levels of GacA and elevated levels of HexA in the FlhDC− mutant are responsible for the inhibition of rsmB RNA production

Performance enhancement of NdFeB nanoflakes prepared by surfactant-assisted ball milling at low temperature by using different surfactants

Science.gov (United States)

An, Xiaoxin; Jin, Kunpeng; Wang, Fang; Fang, Qiuli; Du, Juan; Xia, Weixing; Yan, Aru; Liu, J. Ping; Zhang, Jian

2017-02-01

Hard magnetic NdFeB submicron and nanoflakes were successfully prepared by surfactant-assisted ball milling at room temperature (SABMRT) and low temperature (SABMLT) by using oleic acid (OA), oleylamine (OLA) and trioctylamine (TOA) as surfactant, respectively. Among the surfactants used, OA and OLA have similar effects on the morphology of the NdFeB nanoflakes milled at both room and low temperature. In the case of TOA, irregular micron-sized particles and submirco/nanoflakes were obtained for the NdFeB powders prepared by SABMRT and SABMLT, respectively. Samples prepared by SABMLT show better crystallinity and better degree of grain alignment than that prepared by SABMRT with the same surfactant. Comparing with the samples milled at RT, higher coercivity and larger remanence ratio were achieved in the NdFeB samples prepared at LT. The amounts of residual surfactants in final NdFeB powders were also calculated, which reveals that the final NdFeB powders milled at LT possess lower amount of residual surfactants than those milled at RT. It was found that lowering milling temperature of SABM would be a promising way for fabricating permanent magnetic materials with better hard magnetic properties.

Line-on-line organic-organic heteroepitaxy of quaterrylene on hexa-peri-hexabenzocoronene on Au(111).

Science.gov (United States)

Kasemann, Daniel; Wagner, Christian; Forker, Roman; Dienel, Thomas; Müllen, Klaus; Fritz, Torsten

2009-11-03

In a recent paper, we discussed the optical properties of a heterostructure consisting of a highly ordered monolayer of quaterrylene (QT), electronically decoupled from the gold substrate by a predeposited epitaxial monolayer of hexa-peri-hexabenzocoronene (HBC). Here we now present the detailed structural investigation of this organic double-layer system. We show that the structure of the heterosystem can be identified as line-on-line coincidence (lol), a new type of epitaxy discovered by us previously for the system 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) on HBC on highly oriented pyrolytic graphite (HOPG). Additionally, we provide evidence on the basis of advanced potential energy calculations that indeed energetic gain drives this lol growth mode.

Poly(ethylene oxide) surfactant polymers

OpenAIRE

VACHEETHASANEE, KATANCHALEE; WANG, SHUWU; QIU, YONGXING; MARCHANT, ROGER E.

2004-01-01

We report on a series of structurally well-defined surfactant polymers that undergo surface-induced self-assembly on hydrophobic biomaterial surfaces. The surfactant polymers consist of a poly(vinyl amine) backbone with poly(ethylene oxide) and hexanal pendant groups. The poly(vinyl amine) (PVAm) was synthesized by hydrolysis of poly(N-vinyl formamide) following free radical polymerization of N-vinyl formamide. Hexanal and aldehyde-terminated poly (ethyleneoxide) (PEO) were simultaneously att...

ASSOCIATION OF BRANCHED POLYETHYLENE IMINE WITH SURFACTANTS IN AQUEOUS SOLUTION

Directory of Open Access Journals (Sweden)

Ismael C. Bellettini

2015-07-01

Full Text Available Three polymer-surfactant systems comprised of branched polyethylene imine (PEI with an anionic surfactant (sodium dodecylsulfate; SDS, a cationic surfactant (tetradecyltrimethylammonium bromide; TTAB, and a zwitterionic surfactant (N-tetradecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate; SB3-14 were studied based on the properties of surface tension, pyrene fluorescence emission, dynamic light scattering, pH, and zeta potential measurements. The critical aggregation concentration (cac and polymer saturation point (psp were determined for all three systems. The effect of these surfactants on the physico-chemical characteristics (diameter and surface charge of the complexes formed was determined. Polymer-surfactant interactions occurred in all of the systems studied, with the strongest interactions, electrostatic in nature, occurring in the SDS-PEI system. After the neutralization of the polymer charges with the addition of the surfactant, the hydrophobic effect started to control the interlacing of the polymer chains. For the PEI-TTAB system, a very dense film was formed at surfactant concentrations above 2.0 mmol L-1. In this case, the bromide counter-ion interacted with both the positively-charged PEI and the head of the surfactant, which is responsible for the formation of double layer coordination complexes. For the system composed of PEI and the zwitterionic surfactant, less cooperative associations occurred in comparison with the other systems.

The effect of nanoparticle aggregation on surfactant foam stability.

Science.gov (United States)

AlYousef, Zuhair A; Almobarky, Mohammed A; Schechter, David S

2018-02-01

The combination of nanoparticles (NPs) and surfactant may offer a novel technique of generating stronger foams for gas mobility control. This study evaluates the potential of silica NPs to enhance the foam stability of three nonionic surfactants. Results showed that the concentration of surfactant and NPs is a crucial parameter for foam stability and that there is certain concentrations for strong foam generation. A balance in concentration between the nonionic surfactants and the NPs can enhance the foam stability as a result of forming flocs in solutions. At fixed surfactant concentration, the addition of NPs at low to intermediate concentrations can produce a more stable foam compared to the surfactant. The production of small population of flocs as a result of mixing the surfactant and NPs can enhance the foam stability by providing a barrier between the gas bubbles and delaying the coalescence of bubbles. Moreover, these flocs can increase the solution viscosity and, therefore, slow the drainage rate of thin aqueous film (lamellae). The measurements of foam half-life, bubble size, and mobility tests confirmed this conclusion. However, the addition of more solid particles or surfactant might have a negative impact on foam stability and reduce the maximum capillary pressure of coalescence as a result of forming extensive aggregates. Copyright © 2017 Elsevier Inc. All rights reserved.

Surfactant/detergent titration analysis method and apparatus for machine working fluids, surfactant-containing wastewater and the like

Science.gov (United States)

Smith, Douglas D.; Hiller, John M.

1998-01-01

The present invention is an improved method and related apparatus for quantitatively analyzing machine working fluids and other aqueous compositions such as wastewater which contain various mixtures of cationic, neutral, and/or anionic surfactants, soluble soaps, and the like. The method utilizes a single-phase, non-aqueous, reactive titration composition containing water insoluble bismuth nitrate dissolved in glycerol for the titration reactant. The chemical reaction of the bismuth ion and glycerol with the surfactant in the test solutions results in formation of micelles, changes in micelle size, and the formation of insoluble bismuth soaps. These soaps are quantified by physical and chemical changes in the aqueous test solution. Both classical potentiometric analysis and turbidity measurements have been used as sensing techniques to determine the quantity of surfactant present in test solutions. This method is amenable to the analysis of various types of new, in-use, dirty or decomposed surfactants and detergents. It is a quick and efficient method utilizing a single-phase reaction without needing a separate extraction from the aqueous solution. It is adaptable to automated control with simple and reliable sensing methods. The method is applicable to a variety of compositions with concentrations from about 1% to about 10% weight. It is also applicable to the analysis of waste water containing surfactants with appropriate pre-treatments for concentration.

Surfactant/detergent titration analysis method and apparatus for machine working fluids, surfactant-containing wastewater and the like

Science.gov (United States)

Smith, D.D.; Hiller, J.M.

1998-02-24

The present invention is an improved method and related apparatus for quantitatively analyzing machine working fluids and other aqueous compositions such as wastewater which contain various mixtures of cationic, neutral, and/or anionic surfactants, soluble soaps, and the like. The method utilizes a single-phase, non-aqueous, reactive titration composition containing water insoluble bismuth nitrate dissolved in glycerol for the titration reactant. The chemical reaction of the bismuth ion and glycerol with the surfactant in the test solutions results in formation of micelles, changes in micelle size, and the formation of insoluble bismuth soaps. These soaps are quantified by physical and chemical changes in the aqueous test solution. Both classical potentiometric analysis and turbidity measurements have been used as sensing techniques to determine the quantity of surfactant present in test solutions. This method is amenable to the analysis of various types of new, in-use, dirty or decomposed surfactants and detergents. It is a quick and efficient method utilizing a single-phase reaction without needing a separate extraction from the aqueous solution. It is adaptable to automated control with simple and reliable sensing methods. The method is applicable to a variety of compositions with concentrations from about 1% to about 10% weight. It is also applicable to the analysis of waste water containing surfactants with appropriate pre-treatments for concentration. 1 fig.

Atrazine and Diuron partitioning within a soil-water-surfactant system

Science.gov (United States)

Wang, P.; Keller, A.

2006-12-01

The interaction between pesticide and soil and water is even more complex in the presence of surfactants. In this study, batch equilibrium was employed to study the sorption of surfactants and the partitioning behaviors of Atrazine and Diuron within a soil-water-surfactant system. Five soils and four surfactants (nonionic Triton- 100, cationic Benzalkonium Chloride (BC), anionic Linear Alkylbenzenesulfonate (LAS), and anionic Sodium Dodecyl Sulfate (SDS)) were used. All surfactant sorption isotherms exhibited an initial linear increase at low surfactant concentrations but reached an asymptotic value as the surfactant concentrations increased. Among the surfactants, BC had the highest sorption onto all soils, followed by Triton-100 and then by LAS and SDS, implying that the nature of the charge significantly influences surfactant sorption. Sorption of either Triton-100 or BC was highly correlated with soil Cation Exchange Capacity (CEC) while that of LAS and SDS was complicated by the presence of Ca2+ and Mg2+ in the aqueous phase and the CEC sites. Both LAS and SDS formed complexes with Ca2+ and Mg2+, resulting in a significant decrease in the detergency of the surfactants. At high surfactant concentrations and with micelles present in the aqueous phase, the micelles formed a more competitive partitioning site for the pesticides, resulting in less pesticide sorbed to the soil. At low Triton-100 and BC concentration, the sorption of the surfactants first resulted in less Atrazine sorption but more Diuron sorption, implying competition between the surfactants and Atrazine, which serves as an indirect evidence that there is a different sorption mechanism for Atrazine. Atrazine is a weak base and it protonates and becomes positively charged near particle surfaces where the pH is much lower than in the bulk solution. The protonated Atrazine may then be held on the CEC sites via electrostatic attraction. Triton-100, LAS and SDS sorbed on the soil showed similar

Polyelectrolyte surfactant aggregates and their deposition on macroscopic surfaces

International Nuclear Information System (INIS)

Voisin, David

2002-01-01

Oppositely charged surfactant and polyelectrolyte are present in hair shampoos and conditioners, together with particles (e.g. anti-dandruff agents for scalp) and droplets (e.g. silicone oil for the hair). These are normally formulated at high surfactant concentrations, beyond the flocculation region for the polyelectrolyte concentration used. However, on dilution with water, during application, flocs are formed which carry the particles and droplets to the scalp and hair. The addition of an anionic surfactant to an aqueous solution of cationic polyelectrolyte, at a given concentration, can lead to the formation of polyelectrolyte-surfactant 'particles', in which the surfactant 'binds' to the polyelectrolyte. This occurs from the critical association concentration (CAC), up to the surfactant concentration corresponding to maximum binding. Within this range of surfactant concentrations, the surfactant bound to the polyelectrolyte is thought to associate to form what might be termed 'internal micelles'. Each polyelectrolyte-surfactant particle in the region of the CAC, and just beyond, contains many polyelectrolyte chains, held together essentially by micelle bridges. These particles, however, remain net positively charged, and therefore stable. At the other end of the binding range of the surfactant, so many internal micelles are present that the polymer-surfactant particles are now net negatively charged. Indeed binding stops since no further micelles can be accommodated. Again, the particles are stable. However, there exists a range of surfactant concentrations, lying within the range referred to above, where the net charge is reduced sufficiently that the polymer-surfactant particles will flocculate to form much larger structures. The onset of this second range might be termed the 'critical flocculation concentration' (CFC), and the end, the 'critical stabilisation concentration' (CSC). In this work, the CFC and the CSC have been determined for mixtures of

Generation of HEXA-deficient hiPSCs from fibroblasts of a Tay-Sachs disease patient.

Science.gov (United States)

Liu, Zhong; Zhao, Rui

2016-09-01

Human iPSC line TSD-01-hiPSC was generated from fibroblasts of a patient with infantile Tay-Sachs disease (TSD). The patient is compound heterozygous at the HEXA gene by carrying a 1278insTATC allele and an IVS12+1G>C allele. STEMCCA lentivirus, which expresses OCT4, SOX2, KLF4, and c-MYC from a polycistronic transcript, were used for reprogramming. TSD-01-hiPSC express pluripotency markers such as OCT4, SOX2, NANOG, Tra-1-60, and alkaline phosphatase, and can differentiate into tissues from all the three embryonic germ layers. This TSD patient-derived hiPSC line may serve as a valuable in vitro tool for disease modeling and drug test. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Acute toxicity of anionic and non-ionic surfactants to aquatic organisms.

Science.gov (United States)

Lechuga, M; Fernández-Serrano, M; Jurado, E; Núñez-Olea, J; Ríos, F

2016-03-01

The environmental risk of surfactants requires toxicity measurements. As different test organisms have different sensitivity to the toxics, it is necessary to establish the most appropriate organism to classify the surfactant as very toxic, toxic, harmful or safe, in order to establish the maximum permissible concentrations in aquatic ecosystems. We have determined the toxicity values of various anionic surfactants ether carboxylic derivatives using four test organisms: the freshwater crustacean Daphnia magna, the luminescent bacterium Vibrio fischeri, the microalgae Selenastrum capricornutum (freshwater algae) and Phaeodactylum tricornutum (seawater algae). In addition, in order to compare and classify the different families of surfactants, we have included a compilation of toxicity data of surfactants collected from literature. The results indicated that V. fischeri was more sensitive to the toxic effects of the surfactants than was D. magna or the microalgae, which was the least sensitive. This result shows that the most suitable toxicity assay for surfactants may be the one using V. fischeri. The toxicity data revealed considerable variation in toxicity responses with the structure of the surfactants regardless of the species tested. The toxicity data have been related to the structure of the surfactants, giving a mathematical relationship that helps to predict the toxic potential of a surfactant from its structure. Model-predicted toxicity agreed well with toxicity values reported in the literature for several surfactants previously studied. Predictive models of toxicity is a handy tool for providing a risk assessment that can be useful to establish the toxicity range for each surfactant and the different test organisms in order to select efficient surfactants with a lower impact on the aquatic environment. Copyright © 2015 Elsevier Inc. All rights reserved.

Surfactant protein D in newborn infants

DEFF Research Database (Denmark)

Dahl, Marianne; Juvonen, Pekka Olavi; Holmskov, Uffe

2005-01-01

Surfactant protein D (SP-D) is a collectin that plays an important role in the innate immune system. The role of SP-D in the metabolism of surfactant is as yet quite unclear. The aims of this study were to establish normal values of SP-D in the umbilical cord blood and capillary blood of mature...

Status of surfactants as penetration enhancers in transdermal drug delivery

Directory of Open Access Journals (Sweden)

Iti Som

2012-01-01

Full Text Available Surfactants are found in many existing therapeutic, cosmetic, and agro-chemical preparations. In recent years, surfactants have been employed to enhance the permeation rates of several drugs via transdermal route. The application of transdermal route to a wider range of drugs is limited due to significant barrier to penetration across the skin which is associated with the outermost stratum corneum layer. Surfactants have effects on the permeability characteristics of several biological membranes including skin. They have the potential to solubilize lipids within the stratum corneum. The penetration of the surfactant molecule into the lipid lamellae of the stratum corneum is strongly dependent on the partitioning behavior and solubility of surfactant. Surfactants ranging from hydrophobic agents such as oleic acid to hydrophilic sodium lauryl sulfate have been tested as permeation enhancer to improve drug delivery. This article reviews the status of surfactants as permeation enhancer in transdermal drug delivery of various drugs.

Influence of stability of polymer surfactant on oil displacement mechanism

Science.gov (United States)

Liu, Li; Li, Chengliang; Pi, Yanming; Wu, Di; He, Ying; Geng, Liang

2018-02-01

At present, most of the oilfields of China have entered the late stage of high water-cut development, and three oil recovery technique has become the leading technology for improving oil recovery. With the improvement of three oil recovery techniques, the polymer surfactant flooding technology has been widely promoted in oil fields in recent years. But in the actual field experiment, it has been found that the polymer surfactant has chromatographic separation at the extraction end, which indicates that the property of the polymer surfactant has changed during the displacement process. At present, there was few literature about how the stability of polymer surfactant affects the oil displacement mechanism. This paper used HuaDing-I polymer surfactant to conduct a micro photolithography glass flooding experiment, and then compared the oil displacement law of polymer surfactant before and after static setting. Finally, the influence law of stability of polymer surfactant on the oil displacement mechanism is obtained by comprehensive analysis.

Enhanced solubilization of curcumin in mixed surfactant vesicles.

Science.gov (United States)

Kumar, Arun; Kaur, Gurpreet; Kansal, S K; Chaudhary, Ganga Ram; Mehta, S K

2016-05-15

Self-assemblies of equimolar double and single chain mixed ionic surfactants, with increasing numbers of carbon atoms of double chain surfactant, were analyzed on the basis of fluorescence and conductivity results. Attempts were also made to enhance the solubilization of curcumin in aqueous equimolar mixed surfactant systems. Mixed surfactant assembly was successful in retarding the degradation of curcumin in alkaline media (only 25-28 40% degraded in 10h at pH 13). Fluorescence spectroscopy and fluorescence quenching methods were employed to predict the binding position and mechanism of curcumin with self-assemblies. Results indicate that the interactions take place according to both dynamic and static quenching mechanisms and curcumin was distributed in a palisade layer of mixed aggregates. Antioxidant activity (using DPPH radical) and biocompatibility (using calf-thymus DNA) of curcumin-loaded mixed surfactant formulations were also evaluated. The prepared systems improved the stability, solubility and antioxidant activity of curcumin and additionally are biocompatible. Copyright © 2015 Elsevier Ltd. All rights reserved.

FLOTATION DE-INKING OF 50% ONP/ 50% OMG RECOVERED PAPERS MIXTURES USING NONIONIC SURFACTANT, SOAP, AND SURFACTANT/SOAP BLENDS

Directory of Open Access Journals (Sweden)

Jeremy Allix

2010-11-01

Full Text Available A laboratory flotation column equipped with Venturi aerators and an adjustable froth removal system was used to study the effect of calcium soap and a mixture of calcium soap/alkyl phenol ethoxylate surfactant on ink and fibres transfer during flotation de-inking of a 50% old newprint (ONP / 50% old magazines (OMG recovered papers mixture. Mass transport phenomena determining the yield of the flotation process were interpreted using model equations describing particle removal in terms of flotation, entrainment, and drainage in the froth. A decrease in the ink and mineral fillers flotation rate constant, drainage through the froth, and in fibre entrainment was observed when increasing the surfactant concentration. These trends were consistent with the typical dispersing action of the studied nonionic surfactant. An opposite effect on ink and fillers was observed when using calcium soap alone, and the increase in the flotation rate constant and drainage through the froth were consistent with the collecting and defoaming action of the calcium soap. Moreover, fibre entrainment decreased when increasing the soap concentration. The study of the surfactant/soap mixture highlighted the absence of synergy between the calcium soap and the surfactant.

A novel lignin-based surfactant system for the Salem Unit

International Nuclear Information System (INIS)

DeBons, F.E.; Whittington, L.E.

1991-01-01

Texaco conducted a successful surfactant/polymer flood in a 60-acre [24 ha] portion of the Salem Benoist reservoir in Salem, Illinois, in 1981. This pilot used a brine-tolerant petroleum sulfonate surfactant system blended in injection brine followed by a xanthan mobility control polymer in fresher water. The oil recovery over the seven year life of the flood was 487,050 bbl [77 435 m 3 ]. This represents 45% of the oil remaining in the total thickness of 73% of that from the more permeable lower interval where most of the surfactant flowed. Since this successful project, Texaco has continued to improve enhanced oil recovery surfactant systems. We have developed novel, brine tolerant surfactants based on the renewable resources lignin and tallow amine. This paper describes the laboratory work leading to a surfactant system which has been recommended for field testing. The laboratory work includes blending, interfacial tension measurements, and core floods in Berea and reservoir cores. The type of lignin based surfactant system described in this report has applicability in all fields where conventional petroleum-based surfactants have been used. Their much lower cost means that they can be used economically at lower crude oil prices

Nonlinear vibrational spectroscopy of surfactants at liquid interfaces

Energy Technology Data Exchange (ETDEWEB)

Miranda, Paulo B. [Univ. of California, Berkeley, CA (United States)

1998-12-14

Surfactants are widely used to modify physical and chemical properties of interfaces. They play an important role in many technological problems. Surfactant monolayer are also of great scientific interest because they are two-dimensional systems that may exhibit a very rich phase transition behavior and can also be considered as a model system for biological interfaces. In this Thesis, we use a second-order nonlinear optical technique (Sum-Frequency Generation - SFG) to obtain vibrational spectra of surfactant monolayer at Iiquidhapor and solid/liquid interfaces. The technique has several advantages: it is intrinsically surface-specific, can be applied to buried interfaces, has submonolayer sensitivity and is remarkably sensitive to the confirmational order of surfactant monolayers.

The Inhibiting or Accelerating Effect of Different Surfactants on ...

African Journals Online (AJOL)

The course of differential capacity curves of the electric double layer at the mercury electrode/surfactant solution interface was described for three different surfactants from different groups. Using square-wave voltammetry (SWV) it was found that the surfactants had a varying effect on the kinetics of electroreduction of Zn2+ ...

Effect of Gemini-type surfactant on methane hydrate formation

Energy Technology Data Exchange (ETDEWEB)

Jeong, K.E.; Park, J.M.; Kim, C.U.; Chae, H.J.; Jeong, S.Y. [Korea Research Inst. of Chemical Technology, Jang-Dong, Yuseong-Gu, Daejeon (Korea, Republic of)

2008-07-01

Natural gas hydrates are formed from water and natural gas molecules at particular temperatures and pressures that become ice-like inclusion compounds. Gas hydrates offer several benefits such as energy resource potential and high storage capacity of natural gas in the form of hydrates. However, the application of natural gas hydrates has been deterred by its low formation rate and low conversion ratio of water into hydrate resulting in low actual storage capacity. This paper presented an experimental study to determine the effect of adding a novel Gemini-type surfactant on methane hydrate formation. The experimental study was described with reference to the properties of prepared diols and properties of prepared disulfonates. Gemini surfactant is the family of surfactant molecules possessing more than one hydrophobic tail and hydrophilic head group. They generally have better surface-active properties than conventional surfactants of equal chain length. The paper presented the results of the study in terms of the reactions of diols with propane sultone; storage capacity of hydrate formed with and without surfactant; and methane hydrate formation with and without disulfonate. It was concluded that the methane hydrate formation was accelerated by the addition of novel anionic Gemini-type surfactants and that hydrate formation was influenced by the surfactant concentration and alkyl chain length. For a given concentration, the surfactant with the highest chain length demonstrated the highest formation rate and storage capacity. 5 refs., 3 tabs., 4 figs.

Identifying the Imprint of Surfactant Stabilisation in Whitecap Foam Evolution

Science.gov (United States)

Callaghan, A. H.; Deane, G. B.; Stokes, D.

2016-02-01

Surfactants are ubiquitous in the world's oceans and can affect climatically-relevant processes such as air-sea gas exchange, sea spray aerosol (SSA) flux, and air-sea momentum transfer. Surfactants are amphiphilic and help form the physically and chemically distinct ocean surface microlayer (SML), however, the spatial distribution, concentration and composition of the SML is not well understood, especially under conditions of vigorous wave breaking. Like the SML, breaking waves also influence physical exchange processes at the air-sea interface, and oceanic whitecap foam coverage is commonly used to quantify bubble-mediated exchange processes. However, surfactants can increase the lifetime of foam over clean water conditions, potentially complicating the use of whitecap coverage to parameterise air-sea gas exchange and SSA production flux. A better understanding of how surfactants affect the evolution of whitecap foam is needed to improve whitecap parameterisations of bubble-mediated processes, and may also provide a remote sensing approach to map the spatial distribution of surfactants at the water surface. Here we present results from a laboratory study that looked at whitecap foam evolution in "clean" and "surfactant-added" seawater regimes. We find that the whitecap foam area growth timescale is largely insensitive to the presence of surfactants, but that surfactant stabilization of whitecap foam becomes important during the whitecap foam area decay phase. The timescale at which this occurs appears to be consistent for breaking waves of different scale and intensity. A simple method is then used to isolate the surfactant signal and derive an equivalent "clean" seawater foam decay time for the whitecaps in the "surfactant-added" regime. The method is applied to oceanic whitecaps and results compared to the laboratory whitecaps from the "clean" and "surfactant-added" regimes.

Effective Surfactants Blend Concentration Determination for O/W Emulsion Stabilization by Two Nonionic Surfactants by Simple Linear Regression.

Science.gov (United States)

Hassan, A K

2015-01-01

In this work, O/W emulsion sets were prepared by using different concentrations of two nonionic surfactants. The two surfactants, tween 80(HLB=15.0) and span 80(HLB=4.3) were used in a fixed proportions equal to 0.55:0.45 respectively. HLB value of the surfactants blends were fixed at 10.185. The surfactants blend concentration is starting from 3% up to 19%. For each O/W emulsion set the conductivity was measured at room temperature (25±2°), 40, 50, 60, 70 and 80°. Applying the simple linear regression least squares method statistical analysis to the temperature-conductivity obtained data determines the effective surfactants blend concentration required for preparing the most stable O/W emulsion. These results were confirmed by applying the physical stability centrifugation testing and the phase inversion temperature range measurements. The results indicated that, the relation which represents the most stable O/W emulsion has the strongest direct linear relationship between temperature and conductivity. This relationship is linear up to 80°. This work proves that, the most stable O/W emulsion is determined via the determination of the maximum R² value by applying of the simple linear regression least squares method to the temperature-conductivity obtained data up to 80°, in addition to, the true maximum slope is represented by the equation which has the maximum R² value. Because the conditions would be changed in a more complex formulation, the method of the determination of the effective surfactants blend concentration was verified by applying it for more complex formulations of 2% O/W miconazole nitrate cream and the results indicate its reproducibility.

Polyelectrolyte surfactant aggregates and their deposition on macroscopic surfaces

Energy Technology Data Exchange (ETDEWEB)

Voisin, David

2002-07-01

Oppositely charged surfactant and polyelectrolyte are present in hair shampoos and conditioners, together with particles (e.g. anti-dandruff agents for scalp) and droplets (e.g. silicone oil for the hair). These are normally formulated at high surfactant concentrations, beyond the flocculation region for the polyelectrolyte concentration used. However, on dilution with water, during application, flocs are formed which carry the particles and droplets to the scalp and hair. The addition of an anionic surfactant to an aqueous solution of cationic polyelectrolyte, at a given concentration, can lead to the formation of polyelectrolyte-surfactant 'particles', in which the surfactant 'binds' to the polyelectrolyte. This occurs from the critical association concentration (CAC), up to the surfactant concentration corresponding to maximum binding. Within this range of surfactant concentrations, the surfactant bound to the polyelectrolyte is thought to associate to form what might be termed 'internal micelles'. Each polyelectrolyte-surfactant particle in the region of the CAC, and just beyond, contains many polyelectrolyte chains, held together essentially by micelle bridges. These particles, however, remain net positively charged, and therefore stable. At the other end of the binding range of the surfactant, so many internal micelles are present that the polymer-surfactant particles are now net negatively charged. Indeed binding stops since no further micelles can be accommodated. Again, the particles are stable. However, there exists a range of surfactant concentrations, lying within the range referred to above, where the net charge is reduced sufficiently that the polymer-surfactant particles will flocculate to form much larger structures. The onset of this second range might be termed the 'critical flocculation concentration' (CFC), and the end, the 'critical stabilisation concentration' (CSC). In this work, the CFC and

Mechanical Properties Analysis Of Composite Magnetic Base On hexa ferrite And Polyester Or Epoxy Matrix With Silane Additive Addition

International Nuclear Information System (INIS)

Sudirman; Ridwan; Mujamilah; K K, Aloma; Rembulan, Marisa; Fitriyanti

2003-01-01

Application of composite magnetic especially hexa ferrite magnet for industry and home industry in Indonesia has been used. Research purposes were making composite magnetic by mixing hexa ferrite powder with polyester or epoxy and studying the effect of coupling agent 3-aminopropyltriethoxysilane (3-APE) addition on mechanical properties of composite magnetic. The coupling agent may increase bonding properties between magnetic powder and matrix polymer, so that tensile strength of magnetic composite will increase without decreasing the magnetic properties. Magnetic powder (SrM or BaM) wich be coated by coupling agent were added to matrix polyester and mekpo or epoxy and versamid, mixed until homogen then pressing into to the dumbbell form molding. For epoxy matrix, pressing was done in hot press at 70 deg. C and 150 kg/cm 2 following by cooling in cold press, while for polyester matrix pressing was done in hydraulic press and following by curing at 70 deg. C in an oven for 1 hour. The composition of magnetic powder were varied to 30, 40 and 50% volume fraction and coupling agent were varied to 5, 10 and 15 ml for every volume fraction. The result showed that 10 ml added of coupling agent was give best mechanical properties both polyester and epoxy matrix. However generally, increasing of magnetic powder content decreased the tensile strength of magnetic composite. The properties of magnetic composite SrM was better than BaM either in polyester or epoxy matrix

Variation of intrinsic magnetic parameters of single domain Co-N interstitial nitrides synthesized via hexa-ammine cobalt nitrate route

Energy Technology Data Exchange (ETDEWEB)

Ningthoujam, R.S. [Department of Chemistry, Indian Institute of Technology, Kanpur 208016 (India); Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Panda, R.N., E-mail: rnp@bits-goa.ac.in [Chemistry Group, Birla Institute of Technology and Science-Pilani, Goa Campus, Zuari Nagar, Goa 403726 (India); Gajbhiye, N.S. [Department of Chemistry, Indian Institute of Technology, Kanpur 208016 (India)

2012-05-15

Highlights: Black-Right-Pointing-Pointer Variation of intrinsic magnetic parameters of Co-N. Black-Right-Pointing-Pointer Synthesis by hexa-ammine cobalt complex route. Black-Right-Pointing-Pointer Tuning of coercivity by variation of size. - Abstract: We report the variation of Curie temperature (T{sub c}) and coercivity (H{sub c}) of the single domain Co-N interstitial materials synthesized via nitridation of the hexa-ammine Cobalt(III) nitrate complex at 673 K. Co-N materials crystallize in the fcc cubic structure with unit cell parameter, a = 3.552 Angstrom-Sign . The X-ray diffraction (XRD) peaks are broader indicating the materials to be nano-structured with crystallite sizes of 5-14 nm. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies confirm the nanocrystalline nature of the materials. TEM images show chain-like clusters indicating dipolar interactions between the particles. Magnetic studies focus on the existence of giant magnetic Co atoms in the Co-N lattice that are not influenced by the thermal relaxation. The values of the H{sub c} could be tuned with the dimension of the particles. The values of T{sub c} of the nitride materials are masked by the onset of the ferromagnetic to superparamagnetic transition at higher temperatures. Thermomagnetic studies show an increasing trend in the Curie temperature, T{sub c}, with decrease in particle dimension. This result has been explained qualitatively on the basis of ferromagnetic to superparamagnetic transition and finite size scaling effects.

Effect of surfactant and surfactant blends on pseudoternary phase diagram behavior of newly synthesized palm kernel oil esters

Directory of Open Access Journals (Sweden)

Mahdi ES

2011-06-01

Full Text Available Elrashid Saleh Mahdi1, Mohamed HF Sakeena1, Muthanna F Abdulkarim1, Ghassan Z Abdullah1,3, Munavvar Abdul Sattar2, Azmin Mohd Noor11Department of Pharmaceutical Technology, 2Department of Physiology, School of Pharmaceutical Sciences, Universiti Sains Malaysia, Minden, Penang, Malaysia; 3Department of Pharmaceutical Technology, International Medical University, Bukit Jalil, Kuala Lumpur, MalaysiaBackground: The purpose of this study was to select appropriate surfactants or blends of surfactants to study the ternary phase diagram behavior of newly introduced palm kernel oil esters.Methods: Nonionic surfactant blends of Tween® and Tween®/Span® series were screened based on their solubilization capacity with water for palm kernel oil esters. Tween® 80 and five blends of Tween® 80/Span® 80 and Tween® 80/Span® 85 in the hydrophilic-lipophilic balance (HLB value range of 10.7–14.0 were selected to study the phase diagram behavior of palm kernel oil esters using the water titration method at room temperature.Results: High solubilization capacity was obtained by Tween® 80 compared with other surfactants of Tween® series. High HLB blends of Tween® 80/Span® 85 and Tween® 80/Span® 80 at HLB 13.7 and 13.9, respectively, have better solubilization capacity compared with the lower HLB values of Tween® 80/Span® 80. All the selected blends of surfactants were formed as water-in-oil microemulsions, and other dispersion systems varied in size and geometrical layout in the triangles. The high solubilization capacity and larger areas of the water-in-oil microemulsion systems were due to the structural similarity between the lipophilic tail of Tween® 80 and the oleyl group of the palm kernel oil esters.Conclusion: This study suggests that the phase diagram behavior of palm kernel oil esters, water, and nonionic surfactants is not only affected by the HLB value, but also by the structural similarity between palm kernel oil esters and the surfactant

Tailor-made surfactants for optimized chemical EOR. Meeting oil reservoir conditions by applied knowledge of structure-performance relationship in extended surfactants

Energy Technology Data Exchange (ETDEWEB)

Trahan, G.; Sorensen, W. [Sasol North America Inc., Westlake, LA (United States); Jakobs-Sauter, B. [Sasol Germany GmbH (Germany)

2013-08-01

Formulating the surfactant package for chemical EOR is a time consuming and expensive process - the formulation needs to fit the specific reservoir conditions (like oil type, temperature, salinity, etc.) to give optimum performance and the number of formulation variables is virtually endless. This paper studies the impact of surfactant structure on EOR formulation ability and performance and how to adjust the structure of the surfactant molecule to meet a specific reservoir's needs. Data from salinity phase boundary studies of alcohol propoxy sulfates illustrate how changes in alcohol structure as well as in propylene oxide level can shift optimum salinity and temperature to the desired range in a given model oil. From these data the impact of individual structural units was evaluated. Application of the HLD model (Hydrophilic-Lipophilic Deviation) shows how to extrapolate from the known data set to actual reservoir conditions. This is illustrated by studies on crude oil samples. Additional tests study how effective the selected surfactants perform. The HLD concept proves to be a valuable tool to select and tailor surfactants to individual reservoir needs, thus simplifying the surfactant screening process for EOR formulations by pre-selection of suitable structures and ultimately reducing cost and effort on the way to the most effective chemical EOR package. (orig.)

MICROBIAL SURFACTANTS. I. GLYCOLIPIDS

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Pirog T. Р.

2014-02-01

Full Text Available The review is devoted to surface-active glycolipids. The general characteristics, the physiological role of the rhamnolipids, trehalose lipids, sophorolipids, mannosylerythritol lipids and their traditional producers — the representatives of the genera Pseudozyma, Pseudomonas, Rhodococcus and Candida are given. The detailed analysis of the chemical structure, the stages of the biosynthesis and the regulation of some low molecular glycolipids are done. The own experimental data concerning the synthesis intensification, the physiological role and the practical use of Rhodococcus erythropolis IMV Ac-5017, Acinetobacter calcoaceticus IMV B-7241 and Nocardia vaccinii IMV B-7405 surfactants, which are a complex of the glyco-, phospho-, amino- and neutral lipids (glycolipids of all strains are presented by trehalose mycolates are summarized. It was found that R. erythropolis IMV Ac-5017, A. calcoaceticus IMV B-7241 and N. vaccinii IMV B-7405 surfactants have protective, antimicrobial and antiadhesive properties. It was shown that R. erythropolis IMV Ac-5017, A. calcoaceticus IMV B-7241 and N. vaccinii IMV B-7405 surfactants preparation of cultural liquid intensified the degradation of oil in water due to the activation of the natural petroleum-oxidizing microflora.

Solution processable monosubstituted hexa-peri-hexabenzocoronene self-assembling dyes

Energy Technology Data Exchange (ETDEWEB)

Ren, Shijie; Yan, Chao; Vak, Doojin; Jones, David J.; Holmes, Andrew B.; Wong, Wallace W.H. [School of Chemistry, University of Melbourne, Bio21 Institute, Parkville, Victoria (Australia)

2012-05-23

Molecular organization behavior and visible light absorption ability are important factors for organic materials to be used in efficient bulk heterojunction solar cells applications. In this context, a series of monosubstituted fluorenyl hexa-peri-hexabenzocoronene (FHBC) are synthesized with the aim to combine the self-association property of the FHBC unit with broadened light absorption of a small molecule organic dye, bisthienylbenzothiadiazole (TBT). Optical and electrochemical properties of the FHBC compounds vary according to their structures. Introduction of a TBT unit into the FHBC system broadens the absorption. All of the FHBC compounds show strong {pi}-{pi} intermolecular association in solution. X-ray scattering measurements on thermally extruded filaments and thin films showed ordered alignment of these compounds in the solid state. In atomic force microscopy experiments, nanoscale phase separation is observed in thin films of FHBC and fullerene derivative blends. Solar cell devices with these compounds as donors are fabricated. FHBC compounds with the TBT unit show higher short circuit current while the high open circuit voltages are maintained. With C{sub 60} derivative as acceptor, power conversion efficiency of 1.12% is achieved in the unoptimized solar cell devices under simulated solar irradiation. The efficiency was further improved to 1.64% when C{sub 70} derivative was used as the acceptor. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Serum and sputum surfactants -A and -D in multidrug-resistant and ...

African Journals Online (AJOL)

Abnormal production and function of surfactants are associated with pulmonary diseases. Also, pulmonary infections alter surfactant metabolism. Due to lack of information on the levels of surfactants A (SP-A) and D (SP-D) in Nigerian tuberculosis (TB) patients, this study assessed these surfactants in both sputum and ...

Photoisomerization of merocyanine 540 in polymer-surfactant ...

Indian Academy of Sciences (India)

Photoisomerization of merocyanine 540 (MC540) in a polymer-surfactant aggregate is studied using picosecond time resolved emission spectroscopy. The aggregate consists of the polymer, poly(vinylpyrrolidone) (PVP) and the surfactant, sodium dodecyl sulphate (SDS). With increase in the concentration of SDS in an ...

Dysfunction of pulmonary surfactant mediated by phospholipid oxidation is cholesterol-dependent.

Science.gov (United States)

Al-Saiedy, Mustafa; Pratt, Ryan; Lai, Patrick; Kerek, Evan; Joyce, Heidi; Prenner, Elmar; Green, Francis; Ling, Chang-Chun; Veldhuizen, Ruud; Ghandorah, Salim; Amrein, Matthias

2018-04-01

Pulmonary surfactant forms a cohesive film at the alveolar air-lung interface, lowering surface tension, and thus reducing the work of breathing and preventing atelectasis. Surfactant function becomes impaired during inflammation due to degradation of the surfactant lipids and proteins by free radicals. In this study, we examine the role of reactive nitrogen (RNS) and oxygen (ROS) species on surfactant function with and without physiological cholesterol levels (5-10%). Surface activity was assessed in vitro in a captive bubble surfactometer (CBS). Surfactant chemistry, monolayer fluidity and thermodynamic behavior were also recorded before and after oxidation. We report that physiologic amounts of cholesterol combined with oxidation results in severe impairment of surfactant function. We also show that surfactant polyunsaturated phospholipids are the most susceptible to oxidative alteration. Membrane thermodynamic experiments showed significant surfactant film stiffening after free radical exposure in the presence of cholesterol. These results point to a previously unappreciated role for cholesterol in amplifying defects in surface activity caused by oxidation of pulmonary surfactant, a finding that may have implications for treating several lung diseases. Copyright © 2018 Elsevier B.V. All rights reserved.

Alkyl-imidazolium glycosides: non-ionic-cationic hybrid surfactants from renewable resources.

Science.gov (United States)

Salman, Abbas Abdulameer; Tabandeh, Mojtaba; Heidelberg, Thorsten; Hussen, Rusnah Syahila Duali; Ali, Hapipah Mohd

2015-08-14

A series of surfactants combining carbohydrate and imidazolium head groups were prepared and investigated on their assembly behavior. The presence of the imidazolium group dominated the interactions of the surfactants, leading to high CMCs and large molecular surface areas, reflected in curved rather than lamellar surfactant assemblies. The carbohydrate, on the other hand, stabilized molecular assemblies slightly and reduced the surface tension of surfactant solutions considerably. A comparative emulsion study discourages the use of pure alkyl imidazolium glycosides owing to reduced assembly stabilities compared with APGs. However, the surfactants are believed to have potential as component in carbohydrate based surfactant mixtures. Copyright © 2015 Elsevier Ltd. All rights reserved.

The toxicity of cationic surfactant HDTMA-Br, desorbed from surfactant modified zeolite, towards faecal indicator and environmental microorganisms.

Science.gov (United States)

Reeve, Peter J; Fallowfield, Howard J

2017-10-05

Surfactant Modified Zeolite (SMZ) represents a versatile, cost-effective permeable reactive material, capable of treating multiple classes of contaminants. The potential for HDTMA-Br, a cationic surfactant commonly used to modify zeolite, to desorb from the zeolite surface has been identified as a potential issue for the ongoing use of SMZ in water remediation contexts. This paper investigates the toxicity of HDTMA-Br towards enteric virus surrogates, F-RNA bacteriophage MS2 and E. coli, Bacillus subtilis, and soil microflora. The concentration of surfactant desorbing from SMZ was quantified through a bioassay using E. coli. Results showed HDTMA-Br concentrations of ≥10 -5 M were toxic to MS2, ≥10 -4 M were toxic to E. coli and ≥10 -6 M were toxic to B. subtilis. No toxic relationship was established between HDTMA-Br and soil microflora. Desorption of ≥10 -4 M of HDTMA-Br was shown for the two SMZ samples under the mixing conditions used. Effects of this surfactant on total soil microflora were ambiguous since no toxic relationship could be established, however, HDTMA-Br, at concentrations desorbing from SMZ, were shown to impact the soil bacterium B. subtilis. Further research is required to determine the effect of this surfactant on microbial populations and species diversity in soils. Copyright © 2017 Elsevier B.V. All rights reserved.

Adsorption of dissymmetric cationic gemini surfactants at silica/water interface

Science.gov (United States)

Sun, Yuhai; Feng, Yujun; Dong, Hongwei; Chen, Zhi

2007-05-01

Adsorption of a series of cationic gemini surfactants 12-2- m ( m = 8, 12, 16) on the surface of silica was investigated. The critical micelle concentrations, cmcs, of cationic gemini surfactants in the initial solutions and in the supernatants were measured by conductometry and tensiometer. The changes in cmc values indicate that the ion exchanges take place between polar groups of gemini surfactants adsorbed and ions bound on the surface of silica. The adsorption isotherms of cationic gemini surfactants were obtained by a solution depletion method. Based on the driving force, the adsorption includes two steps, one of which is ion exchange, and the other is hydrophobic interaction. In each step, the tendency of surfactant molecules in the solution to form aggregates or to be adsorbed on the silica varies with their structures. The maximum adsorption amount of gemini surfactants on the silica, τmax, decreases as increasing in the length of one alkyl chain, m, from 8, 12 to 16. So the results show that the adsorption behaviors of gemini surfactants are closely related to the dissymmetry of gemini molecules.

Surfactant-Enhanced Benard Convection on an Evaporating Drop

Science.gov (United States)

Nguyen, Van X.; Stebe, Kathleen J.

2001-11-01

Surfactant effects on an evaporating drop are studied experimentally. Using a fluorescent probe, the distribution and surface phase of the surfactant is directly imaged throughout the evaporation process. From these experiments, we identify conditions in which surfactants promote surface tension-driven Benard instabilities in aqueous systems. The drops under study contain finely divided particles, which act as tracers in the flow, and form well-defined patterns after the drop evaporates. Two flow fields have been reported in this system. The first occurs because the contact line becomes pinned by solid particles at the contact line region. In order for the contact line to remain fixed, an outward flow toward the ring results, driving further accumulation at the contact ring. A ‘coffee ring’ of particles is left as residue after the drop evaporates[1]. The second flow is Benard convection, driven by surface tension gradients on the drop[2,3]. In our experiments, an insoluble monolayer of pentadecanoic acid is spread at the interface of a pendant drop. The surface tension is recorded, and the drop is deposited on a well-defined solid substrate. Fluorescent images of the surface phase of the surfactant are recorded as the drop evaporates. The surfactant monolayer assumes a variety of surface states as a function of the area per molecule at the interface: surface gaseous, surface liquid expanded, and surface liquid condensed phases[4]. Depending upon the surface state of the surfactant as the drop evaporates, transitions of residue patterns left by the particles occur, from the coffee ring pattern to Benard cells to irregular patterns, suggesting a strong resistance to outward flow are observed. The occurrence of Benard cells on a surfactant-rich interface occurs when the interface is in LE-LC coexistence. Prior research concerning surfactant effects on this instability predict that surfactants are strongly stabilizing[5]. The mechanisms for this change in behavior

Gemini Surfactant-Modified Activated Carbon for Remediation of Hexavalent Chromium from Water

Directory of Open Access Journals (Sweden)

Yingying Zhou

2018-01-01

Full Text Available Gemini surfactants, with double hydrophilic and hydrophobic groups, offer potentially orders of magnitude greater surface activity compared to similar single unit molecules. A cationic Gemini surfactant (Propyl didodecyldimethylammonium Bromide, PDDDAB and a conventional cationic surfactant (Dodecyltrimethylammonium Bromide, DTAB were used to pre-treat and generate activated carbon. The removal efficiency of the surfactant-modified activated carbon through adsorption of chromium(VI was investigated under controlled laboratory conditions. Fourier-transform infrared spectroscopy (FT-IR and scanning electron microscopy (SEM were used to investigate the surface changes of surfactant-modified activated carbon. The effect of important parameters such as adsorbent dosage, pH, ionic strength and contact time were also investigated. The chromium(VI was adsorbed more significantly on the Gemini surfactant-modified activated carbon than on the conventional surfactant-modified activated carbon. The correlation coefficients show the data best fit the Freundlich model, which confirms the monolayer adsorption of chromium(VI onto Gemini surfactant-modified activated carbon. From this assessment, the surfactant-modified (especially Gemini surfactant-modified activated carbon in this study showed promise for practical applications to treat water pollution.

Method of cement-solidification of radioactive liquid wastes containing surfactant

Energy Technology Data Exchange (ETDEWEB)

Sugimoto, Y; Yusa, H

1979-04-10

Purpose: To provide the subject method comprising the steps of adjusting the concentration of the surfactant to a value less than the predetermined value even when the concentration of the surfactant is high, and rendering the uniaxial compression strength of the cement-solidification body into more than the defined fabrication reference value. Method: To radioactive liquid wastes there are applied means for boiling and heating liquid wastes by addition of sulfuric acid, means for cracking surfactants by the addition of oxidants and means for precipitating and arresting surfactants. After suppressing the hindrance of the cement hydration reaction by surfactants, the radioactive liquid wastes are cement-solidified. (Nakamura, S.).

Controlling block copolymer phase behavior using ionic surfactant

Energy Technology Data Exchange (ETDEWEB)

Ray, D.; Aswal, V. K. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India E-mail: debes.phys@gmail.com (India)

2016-05-23

The phase behavior of poly(ethylene oxide)-poly(propylene oxide-poly(ethylene oxide) PEO-PPO-PEO triblock copolymer [P85 (EO{sub 26}PO{sub 39}EO{sub 26})] in presence of anionic surfactant sodium dodecyl sulfate (SDS) in aqueous solution as a function of temperature has been studied using dynamic light scattering (DLS) and small-angle neutron scattering (SANS). The measurements have been carried out for fixed concentrations (1 wt%) of block copolymer and surfactants. Each of the individual components (block copolymer and surfactant) and the nanoparticle–surfactant mixed system have been examined at varying temperature. The block copolymer P85 forms spherical micelles at room temperature whereas shows sphere-to-rod like micelle transition at higher temperatures. On the other hand, SDS surfactant forms ellipsoidal micelles over a wide temperature range. Interestingly, it is found that phase behavior of mixed micellar system (P85 + SDS) as a function of temperature is drastically different from that of P85, giving the control over the temperature-dependent phase behavior of block copolymers.

Aerobic biodegradation of amphoteric amine-oxide-based surfactants: Effect of molecular structure, initial surfactant concentration and pH.

Science.gov (United States)

Ríos, Francisco; Lechuga, Manuela; Fernández-Serrano, Mercedes; Fernández-Arteaga, Alejandro

2017-03-01

The present study was designed to provide information regarding the effect of the molecular structure of amphoteric amine-oxide-based surfactants and the initial surfactant concentration on their ultimate biodegradation. Moreover, given this parameter's pH-dependence, the effect of pH was also investigated. Three amine-oxide-based surfactants with structural differences in their hydrophobic alkyl chain were tested: Lauramine oxide (AO-R 12 ), Myristamine oxide (AO-R 14 ) and Cocamidopropylamine oxide (AO-Cocoamido). We studied the ultimate biodegradation using the Modified OECD Screening Test at initial surfactant concentrations ranged from 5 to 75 mg L -1 and at pH levels from 5 to 7.4. The results demonstrate that at pH 7.4, amine-oxide-based surfactants are readily biodegradable. In this study, we concluded that ω-oxidation can be assumed to be the main biodegradation pathway of amine-oxides and that differences in the biodegradability between them can be explained by the presence of an amide group in the alkyl chain of AO-Cocoamido; the CN fission of the amide group slows down their mineralization process. In addition, the increase in the concentration of the surfactant from 5 to 75 mg L -1 resulted in an increase in the final biodegradation of AO-R 12 and AO-R 14 . However, in the case of AO-Cocoamido, a clear relationship between the concentration and biodegradation cannot be stated. Conversely, the biodegradability of AO-R 12 and AO-R 14 was considerably lower in an acid condition than at a pH of 7.4, whereas AO-Cocoamido reached similar percentages in acid conditions and at a neutral pH. However, microorganisms required more time to acclimate. Copyright © 2016 Elsevier Ltd. All rights reserved.

Laser-heating-induced displacement of surfactants on the water surface

NARCIS (Netherlands)

Backus, E.H.G.; Bonn, D.; Cantin, S.; Roke, S.; Bonn, M.

2012-01-01

We report a combined vibrational sum-frequency generation (SFG) spectroscopy, Brewster angle microscopy (BAM), and ellipsometry study of different surfactants on water as a function of surfactant density. Vibrational SFG spectra of surfactants on the water surface in a Langmuir trough have been

Molecular-thermodynamic theory of micellization of pH-sensitive surfactants.

Science.gov (United States)

Goldsipe, Arthur; Blankschtein, Daniel

2006-04-11

A predictive, molecular-thermodynamic theory is developed to model the micellization of pH-sensitive surfactants. The theory combines a molecular-thermodynamic description of micellization in binary surfactant mixtures with the protonation equilibrium of the surfactant monomers. The thermodynamic component of the theory models the pH-mediated equilibrium between micelles, surfactant monomers, and counterions. These counterions may originate from the surfactant or from added salt, acid, or base. The molecular component of the theory models the various contributions to the free energy of micellization, which corresponds to the free-energy change associated with forming a mixed micelle from the protonated and deprotonated forms of the surfactant and from the bound counterions. The free energy of micellization includes hydrophobic, interfacial, packing, steric, electrostatic, and entropic contributions, which are all calculated molecularly. The theory also requires knowledge of the surfactant molecular structure and the solution conditions, including the temperature and the amount of any added salt, acid, or base. To account for the pH sensitivity of the surfactant, the theory requires knowledge of the surfactant monomer equilibrium deprotonation constant (pK1), which may be obtained from experimental titration data obtained below the critical micelle concentration (cmc). The theory can be utilized to predict the equilibrium micelle and solution properties, including the cmc, the micelle composition, the micelle shape and aggregation number, the solution pH, and the micelle deprotonation equilibrium constant (pKm). Theoretical predictions of the cmc, the micelle aggregation number, and the pKm compare favorably with the available experimental data for alkyldimethylamine oxide surfactants. This class of pH-sensitive surfactants exhibits a form of self-synergy, which has previously been attributed to hydrogen-bond formation at the micelle interface. Instead, we show that

A multicenter, randomized trial comparing synthetic surfactant with modified bovine surfactant extract in the treatment of neonatal respiratory distress syndrome

NARCIS (Netherlands)

Adams, E; Vollman, J; Giebner, D; Maurer, M; Dreyer, G; Bailey, L; Anderson, M; Mefford, L; Beaumont, E; Sutton, D; Puppala, B; Mangurten, HH; Secrest, J; Lewis, WJ; Carteaux, P; Bednarek, F; Welsberger, S; Gosselin, R; Pantoja, AF; Belenky, A; Campbell, P; Patole, S; Duenas, M; Kelly, M; Alejo, W; Lewallen, P; DeanLieber, S; Hanft, M; Ferlauto, J; Newell, RW; Bagwell, J; Levine, D; Lipp, RW; Harkavy, K; Vasa, R; Birenbaum, H; Broderick, KA; Santos, AQ; Long, BA; Gulrajani, M; Stern, M; Hopgood, G; Hegyi, T; Alba, J; Christmas, L; McQueen, M; Nichols, N; Brown, M; Quissell, BJ; Rusk, C; Marks, K; Gifford, K; Hoehn, G; Pathak, A; Marino, B; Hunt, P; Fox, [No Value; Sharpstein, C; Feldman, B; Johnson, N; Beecham, J; Balcom, R; Helmuth, W; Boylan, D; Frakes, C; Magoon, M; Reese, K; Schwersenski, J; Schutzman, D; Soll, R; Horbar, JD; Leahy, K; Troyer, W; Juzwicki, C; Anderson, P; Dworsky, M; Reynolds, L; Urrutia, J; Gupta, U; Adray, C

Objective. To compare the efficacy of a synthetic surfactant (Exosurf Neonatal, Burroughs-Wellcome Co) and a modified bovine surfactant extract (Survanta, Ross Laboratories) in the treatment of neonatal respiratory distress syndrome (RDS). Design. Multicenter, randomized trial. Setting. Thirty-eight

Early surfactant therapy and nasal continuous positive airways ...

African Journals Online (AJOL)

respiratory distress syndrome (RDS) receiving nasal continuous positive airways ... required FiO2 was allowed to rise above 0.4 before surfactant was administered. ... group received surfactant immediately and the high-threshold group ...

A novel biosensor method for surfactant determination based on acetylcholinesterase inhibition

International Nuclear Information System (INIS)

Kucherenko, I S; Soldatkin, O O; Arkhypova, V M; Dzyadevych, S V; Soldatkin, A P

2012-01-01

A novel enzyme biosensor based on acetylcholinesterase inhibition for the determination of surfactants in aqueous solutions is described. Acetylcholinesterase-based bioselective element was deposited via glutaraldehyde on the surface of conductometric transducers. Different variants of inhibitory analysis of surfactants were tested, and finally surfactant's concentration was evaluated by measuring initial rate of acetylcholinesterase inhibition. Besides, we studied the effect of solution characteristics on working parameters of the biosensor for direct measurement of acetylcholine and for inhibitory determination of surfactants. The biosensor's sensitivity to anionic and cationic surfactants (0.35 mg l −1 ) was tested. The high operational stability of the biosensor during determination of acetylcholine (RSD 2%) and surfactants (RSD 11%) was shown. Finally, we discussed the selectivity of the biosensor toward surfactants and other AChE inhibitors. The proposed biosensor can be used as a component of the multibiosensor for ecological monitoring of toxicants. (paper)

Effect of surfactant types and their concentration on the structural characteristics of nanoclay

Science.gov (United States)

Zawrah, M. F.; Khattab, R. M.; Saad, E. M.; Gado, R. A.

2014-03-01

A series of organo-modified nanoclays was synthesized using three different surfactants having different alkyl chain lengths and concentrations [0.5-5.0 cation exchange capacity (CEC)]. These surfactants were Ethanolamine (EA), Cetyltrimethylammoniumbromide (CTAB) and Tetraoctadecylammoniumbromide (TO). The obtained modified nanoclays were characterized by X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) and compared with unmodified nanoclay. The results of XRD analysis indicated that the basal d-spacing has increased with increasing alkyl chain length and surfactant concentration. From the obtained microstructures of these organo-modified nanoclays, the mechanism of surfactant adsorption was proposed. At relatively low loading of surfactant, most of surfactant entered the spacing by an ion-exchange mechanism and is adsorbed onto the interlayer cation sites. When the concentration of the surfactant exceeds the CEC of clay, the surfactant molecules then adhere to the surface adsorbed surfactant. Some surfactants entered the interlayers, whereas the others were attached to the clay surface. When the concentration of surfactant increased further beyond 2.0 CEC, the surfactants might occupy the inter-particle space within the house-of-cards aggregate structure.

Nanoparticle decoration with surfactants: Molecular interactions, assembly, and applications

Science.gov (United States)

Heinz, Hendrik; Pramanik, Chandrani; Heinz, Ozge; Ding, Yifu; Mishra, Ratan K.; Marchon, Delphine; Flatt, Robert J.; Estrela-Lopis, Irina; Llop, Jordi; Moya, Sergio; Ziolo, Ronald F.

2017-02-01

Nanostructures of diverse chemical nature are used as biomarkers, therapeutics, catalysts, and structural reinforcements. The decoration with surfactants has a long history and is essential to introduce specific functions. The definition of surfactants in this review is very broad, following its lexical meaning ;surface active agents;, and therefore includes traditional alkyl modifiers, biological ligands, polymers, and other surface active molecules. The review systematically covers covalent and non-covalent interactions of such surfactants with various types of nanomaterials, including metals, oxides, layered materials, and polymers as well as their applications. The major themes are (i) molecular recognition and noncovalent assembly mechanisms of surfactants on the nanoparticle and nanocrystal surfaces, (ii) covalent grafting techniques and multi-step surface modification, (iii) dispersion properties and surface reactions, (iv) the use of surfactants to influence crystal growth, as well as (v) the incorporation of biorecognition and other material-targeting functionality. For the diverse materials classes, similarities and differences in surfactant assembly, function, as well as materials performance in specific applications are described in a comparative way. Major factors that lead to differentiation are the surface energy, surface chemistry and pH sensitivity, as well as the degree of surface regularity and defects in the nanoparticle cores and in the surfactant shell. The review covers a broad range of surface modifications and applications in biological recognition and therapeutics, sensors, nanomaterials for catalysis, energy conversion and storage, the dispersion properties of nanoparticles in structural composites and cement, as well as purification systems and classical detergents. Design principles for surfactants to optimize the performance of specific nanostructures are discussed. The review concludes with challenges and opportunities.

Gemini (dimeric) Surfactants

Indian Academy of Sciences (India)

is in turn bonded to an identical hydrocarbon tail; alternatively,. ~. Tail spacer ... formed is dependent on surfactant structure, temperature, ionic strength and pH. The models of GS are .... micelle to the air/water interface. Moreover, GS can be ...

The impact of alkyl sulfate surfactant geometry and electrolyte on the co-adsorption of anionic surfactants with model perfumes at the air-solution interface.

Science.gov (United States)

Bradbury, Robert; Penfold, Jeffrey; Thomas, Robert K; Tucker, Ian M; Petkov, Jordan T; Jones, Craig

2013-08-01

The impact of surfactant geometry and electrolyte on the co-adsorption of anionic surfactants and model perfumes at the air-solution interface has been studied by neutron reflectivity. The more hydrophobic perfume linalool, competes more favourably for the surface with sodium dodecylsulfate than was previously reported for the anionic surfactant, sodium dodecyl 6-benzenesulfonate. Due to an increase in surface activity of the sodium dodecylsulfate, the addition of electrolyte results in a reduction in the linalool adsorption. Changing the alkyl chain length affects the relative adsorption of linalool and surfactant at the interface. Similar measurements for the different alkyl sulfates and with electrolyte with the more hydrophilic perfume phenyl ethanol, reveal broadly similar trends. Although the relative adsorption of phenyl ethanol with sodium dodecylsulfate is substantially enhanced compared to sodium dodecyl-6-benzenesulfonate the effects are not as significant as was observed with linalool. The variations with alkyl chain geometry show the importance of the hydrophobic interaction between the perfume and surfactant and changes in the packing constraints on the relative adsorption. The results highlight the importance of the specific interaction between the surfactant and perfume, and the surfactant and perfume geometries on the relative adsorption at the interface. Copyright © 2013 Elsevier Inc. All rights reserved.

Micellar solubilization in strongly interacting binary surfactant systems. [Binary surfactant systems of: dodecyltrimethylammonium chloride + sodium dodecyl sulfate; benzyldimethyltetradecylammonium chloride + tetradecyltrimethylammonium chloride

Energy Technology Data Exchange (ETDEWEB)

Treiner, C. (Universite Pierre et Marie Curie, Paris (France)); Nortz, M.; Vaution, C. (Faculte de Pharmacie de Paris-sud, Chatenay-Malabry (France))

1990-07-01

The apparent partition coefficient P of barbituric acids between micelles and water has been determined in mixed binary surfactant solutions from solubility measurements in the whole micellar composition range. The binary systems chosen ranged from the strongly interacting system dodecyltrimethylammonium chloride + sodium dodecyl sulfate to weakly interacting systems such as benzyldimethyltetradecylammonium chloride + tetradecyltrimethyammonium chloride. In all cases studied, mixed micelle formation is unfavorable to micellar solubilization. A correlation is found between the unlike surfactants interaction energy, as measured by the regular solution parameter {beta} and the solute partition coefficient change upon surfactant mixing. By use of literature data on micellar solubilization in binary surfactant solutions, it is shown that the change of P for solutes which are solubilized by surface adsorption is generally governed by the sign and amplitude of the interaction parameter {beta}.

Complex phase behavior in solvent-free nonionic surfactants

DEFF Research Database (Denmark)

Hillmyer, M.A.; Bates, F.S.; Almdal, K.

1996-01-01

Unsolvated block copolymers and surfactant solutions are ''soft materials'' that share a common set of ordered microstructures, A set of polyethyleneoxide-polyethylethylene (PEG-PEE) block copolymers that are chemically similar to the well-known alkane-oxyethylene (C(n)EO(m)) nonionic surfactants...... was synthesized here. The general phase behavior in these materials resembles that of both higher molecular weight block copolymers and lower molecular weight nonionic surfactant solutions. Two of the block copolymers exhibited thermally induced order-order transitions and were studied in detail by small...

Biodegradability of bacterial surfactants.

Science.gov (United States)

Lima, Tânia M S; Procópio, Lorena C; Brandão, Felipe D; Carvalho, André M X; Tótola, Marcos R; Borges, Arnaldo C

2011-06-01

This work aimed at evaluating the biodegradability of different bacterial surfactants in liquid medium and in soil microcosms. The biodegradability of biosurfactants by pure and mixed bacterial cultures was evaluated through CO(2) evolution. Three bacterial strains, Acinetobacter baumanni LBBMA ES11, Acinetobacter haemolyticus LBBMA 53 and Pseudomonas sp. LBBMA 101B, used the biosurfactants produced by Bacillus sp. LBBMA 111A (mixed lipopeptide), Bacillus subtilis LBBMA 155 (lipopeptide), Flavobacterium sp. LBBMA 168 (mixture of flavolipids), Dietzia Maris LBBMA 191(glycolipid) and Arthrobacter oxydans LBBMA 201(lipopeptide) as carbon sources in minimal medium. The synthetic surfactant sodium dodecyl sulfate (SDS) was also mineralized by these microorganisms, but at a lower rate. CO(2) emitted by a mixed bacterial culture in soil microcosms with biosurfactants was higher than in the microcosm containing SDS. Biosurfactant mineralization in soil was confirmed by the increase in surface tension of the soil aqueous extracts after incubation with the mixed bacterial culture. It can be concluded that, in terms of biodegradability and environmental security, these compounds are more suitable for applications in remediation technologies in comparison to synthetic surfactants. However, more information is needed on structure of biosurfactants, their interaction with soil and contaminants and scale up and cost for biosurfactant production.

Single well surfactant test to evaluate surfactant floods using multi tracer method

Science.gov (United States)

Sheely, Clyde Q.

1979-01-01

Data useful for evaluating the effectiveness of or designing an enhanced recovery process said process involving mobilizing and moving hydrocarbons through a hydrocarbon bearing subterranean formation from an injection well to a production well by injecting a mobilizing fluid into the injection well, comprising (a) determining hydrocarbon saturation in a volume in the formation near a well bore penetrating formation, (b) injecting sufficient mobilizing fluid to mobilize and move hydrocarbons from a volume in the formation near the well bore, and (c) determining the hydrocarbon saturation in a volume including at least a part of the volume of (b) by an improved single well surfactant method comprising injecting 2 or more slugs of water containing the primary tracer separated by water slugs containing no primary tracer. Alternatively, the plurality of ester tracers can be injected in a single slug said tracers penetrating varying distances into the formation wherein the esters have different partition coefficients and essentially equal reaction times. The single well tracer method employed is disclosed in U.S. Pat. No. 3,623,842. This method designated the single well surfactant test (SWST) is useful for evaluating the effect of surfactant floods, polymer floods, carbon dioxide floods, micellar floods, caustic floods and the like in subterranean formations in much less time and at much reduced cost compared to conventional multiwell pilot tests.

Pyrene removal from contaminated soil using electrokinetic process combined with surfactant

Directory of Open Access Journals (Sweden)

Seyed Enayat Hashemi

2015-07-01

Full Text Available Background: Pyrene is one of the stable polycyclic aromatic hydrocarbons that is considered as an important pollutants, because of extensive distribution in the environment and carcinogenic and mutagenic properties. Among the various treatment techniques, electrokinetic method is an environmental- friendly process for organic and mineral pollutants adsorbed to soil with fine pore size the same as clay and low hydraulic conductivity soils. For improving the efficiency of pyrene removal from soil, soulobilization of pyrene from soil could be used by surfactants. Materials and Methods : In this study, clay soil was selected as model because of the specific properties. Combined method using surfactant and electrokinetic was applied for pyrene removal from soil. Experiments were designed using response surface methodology (RSM, and effect of three variables includes surfactant concentration, voltage and surfactant type were evaluated for pyrene removal from contaminated soil. Results: Pyrene removal using anionic surfactants(SDS and nonionic surfactants(TX100 as a solubilizing agents has high removal efficiency. In the optimum condition with 95% confidence coefficient, utilizing mixed surfactants of sodium dodecyl sulfate and triton X-100 with the same volume, induced of 18.54 volt and 6.53 percent surfactant concentration have 94.6% pyrene removal efficiency. Conclusion:: Results of this study shows that electrokinetic process combined with surfactant as solubilizing agent could be applied as an efficient method for treating the pyrene-contaminated soils.

Enhanced Oil Recovery with Surfactant Flooding

DEFF Research Database (Denmark)

Sandersen, Sara Bülow

, thus reducing the interfacial tension (IFT) to ultra low (0.001 mN/m), which consequently will mobilize the residual oil and result in improved oil recovery. This EOR technology is, however, made challenging by a number of factors, such as the adsorption of surfactant and co-surfactant to the rock...... be resistant to and remain active at reservoir conditions such as high temperatures, pressures and salinities. Understanding the underlying mechanisms of systems that exhibit liquid-liquid equilibrium (e.g. oil-brine systems) at reservoir conditions is an area of increasing interest within EOR. This is true...... studied. The effect of increased pressure became more significant when combined with increasing temperature. The experiments performed on the oil/ seawater systems were similar to the high pressure experiments for the surfactant system discussed above. Oil was contacted with different brine solutions...

Determination of the critical micelle concentration in simulations of surfactant systems

Energy Technology Data Exchange (ETDEWEB)

Santos, Andrew P.; Panagiotopoulos, Athanassios Z., E-mail: azp@princeton.edu [Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544 (United States)

2016-01-28

Alternative methods for determining the critical micelle concentration (cmc) are investigated using canonical and grand canonical Monte Carlo simulations of a lattice surfactant model. A common measure of the cmc is the “free” (unassociated) surfactant concentration in the presence of micellar aggregates. Many prior simulations of micellizing systems have observed a decrease in the free surfactant concentration with overall surfactant loading for both ionic and nonionic surfactants, contrary to theoretical expectations from mass-action models of aggregation. In the present study, we investigate a simple lattice nonionic surfactant model in implicit solvent, for which highly reproducible simulations are possible in both the canonical (NVT) and grand canonical (μVT) ensembles. We confirm the previously observed decrease of free surfactant concentration at higher overall loadings and propose an algorithm for the precise calculation of the excluded volume and effective concentration of unassociated surfactant molecules in the accessible volume of the solution. We find that the cmc can be obtained by correcting the free surfactant concentration for volume exclusion effects resulting from the presence of micellar aggregates. We also develop an improved method for determination of the cmc based on the maximum in curvature for the osmotic pressure curve determined from μVT simulations. Excellent agreement in cmc and other micellar properties between NVT and μVT simulations of different system sizes is observed. The methodological developments in this work are broadly applicable to simulations of aggregating systems using any type of surfactant model (atomistic/coarse grained) or solvent description (explicit/implicit)

Determination of the critical micelle concentration in simulations of surfactant systems.

Science.gov (United States)

Santos, Andrew P; Panagiotopoulos, Athanassios Z

2016-01-28

Alternative methods for determining the critical micelle concentration (cmc) are investigated using canonical and grand canonical Monte Carlo simulations of a lattice surfactant model. A common measure of the cmc is the "free" (unassociated) surfactant concentration in the presence of micellar aggregates. Many prior simulations of micellizing systems have observed a decrease in the free surfactant concentration with overall surfactant loading for both ionic and nonionic surfactants, contrary to theoretical expectations from mass-action models of aggregation. In the present study, we investigate a simple lattice nonionic surfactant model in implicit solvent, for which highly reproducible simulations are possible in both the canonical (NVT) and grand canonical (μVT) ensembles. We confirm the previously observed decrease of free surfactant concentration at higher overall loadings and propose an algorithm for the precise calculation of the excluded volume and effective concentration of unassociated surfactant molecules in the accessible volume of the solution. We find that the cmc can be obtained by correcting the free surfactant concentration for volume exclusion effects resulting from the presence of micellar aggregates. We also develop an improved method for determination of the cmc based on the maximum in curvature for the osmotic pressure curve determined from μVT simulations. Excellent agreement in cmc and other micellar properties between NVT and μVT simulations of different system sizes is observed. The methodological developments in this work are broadly applicable to simulations of aggregating systems using any type of surfactant model (atomistic/coarse grained) or solvent description (explicit/implicit).

Determination of the critical micelle concentration in simulations of surfactant systems

International Nuclear Information System (INIS)

Santos, Andrew P.; Panagiotopoulos, Athanassios Z.

2016-01-01

Alternative methods for determining the critical micelle concentration (cmc) are investigated using canonical and grand canonical Monte Carlo simulations of a lattice surfactant model. A common measure of the cmc is the “free” (unassociated) surfactant concentration in the presence of micellar aggregates. Many prior simulations of micellizing systems have observed a decrease in the free surfactant concentration with overall surfactant loading for both ionic and nonionic surfactants, contrary to theoretical expectations from mass-action models of aggregation. In the present study, we investigate a simple lattice nonionic surfactant model in implicit solvent, for which highly reproducible simulations are possible in both the canonical (NVT) and grand canonical (μVT) ensembles. We confirm the previously observed decrease of free surfactant concentration at higher overall loadings and propose an algorithm for the precise calculation of the excluded volume and effective concentration of unassociated surfactant molecules in the accessible volume of the solution. We find that the cmc can be obtained by correcting the free surfactant concentration for volume exclusion effects resulting from the presence of micellar aggregates. We also develop an improved method for determination of the cmc based on the maximum in curvature for the osmotic pressure curve determined from μVT simulations. Excellent agreement in cmc and other micellar properties between NVT and μVT simulations of different system sizes is observed. The methodological developments in this work are broadly applicable to simulations of aggregating systems using any type of surfactant model (atomistic/coarse grained) or solvent description (explicit/implicit)

LOWER COST METHODS FOR IMPROVED OIL RECOVERY (IOR) VIA SURFACTANT FLOODING

Energy Technology Data Exchange (ETDEWEB)

William A. Goddard III; Yongchun Tang; Patrick Shuler; Mario Blanco; Seung Soon Jang; Shiang-Tai Lin; Prabal Maiti; Yongfu Wu; Stefan Iglauer; Xiaohang Zhang

2004-09-01

This report provides a summary of the work performed in this 3-year project sponsored by DOE. The overall objective of this project is to identify new, potentially more cost-effective surfactant formulations for improved oil recovery (IOR). The general approach is to use an integrated experimental and computational chemistry effort to improve our understanding of the link between surfactant structure and performance, and from this knowledge, develop improved IOR surfactant formulations. Accomplishments for the project include: (1) completion of a literature review to assemble current and new surfactant IOR ideas, (2) Development of new atomistic-level MD (molecular dynamic) modeling methodologies to calculate IFT (interfacial tension) rigorously from first principles, (3) exploration of less computationally intensive mesoscale methods to estimate IFT, Quantitative Structure Property Relationship (QSPR), and cohesive energy density (CED) calculations, (4) experiments to screen many surfactant structures for desirable low IFT and solid adsorption behavior, and (5) further experimental characterization of the more promising new candidate formulations (based on alkyl polyglycosides (APG) and alkyl propoxy sulfate surfactants). Important findings from this project include: (1) the IFT between two pure substances may be calculated quantitatively from fundamental principles using Molecular Dynamics, the same approach can provide qualitative results for ternary systems containing a surfactant, (2) low concentrations of alkyl polyglycoside surfactants have potential for IOR (Improved Oil Recovery) applications from a technical standpoint (if formulated properly with a cosurfactant, they can create a low IFT at low concentration) and also are viable economically as they are available commercially, and (3) the alkylpropoxy sulfate surfactants have promising IFT performance also, plus these surfactants can have high optimal salinity and so may be attractive for use in higher

The effect of surfactant on pollutant biosorption of Trametes versicolor

Science.gov (United States)

Gül, Ülküye Dudu; Silah, Hülya; Akbaş, Halide; Has, Merve

2016-04-01

The major problem concerning industrial wastewater is treatment of dye and heavy metal containing effluents. Industrial effluents are also contained surfactants that are used as levelling, dispersing and wetting agents. The purpose of this study was to investigate the effect of surfactant on textile dye biosorption properties of a white rot fungus named Trametes versicolor. Reactive dyes are commonly used in textile industry because of their advantages such as brightness and excellent color fastness. A recative textile dye, called Everzol Black, was used in this study. The low-cost mollasses medium is used for fungal growth. The usage of mollases, the sugar refinery effluent as a source of energy and nutrients, gained importance because of reducing the cost and also reusing another waste. In biosorption process the effect of surfactant on dye removal properties of T. versicolor was examined as a function of pH, dye consentration and surfactant concentration. The results of this study showed that the surfactant enhanced the dye removal capacity of Trametes versicolor. The dye and surfactant molecules were interacted electrostatically and these electrostatic interactions improved dye removal properties of filamentous fungus T. versicolor. The results of this study recommended the use of surfactants as an inducer in textile wastewater treatment technologies.

Surfactant-enhanced recovery of dissolved hydrocarbons at petroleum production facilities

International Nuclear Information System (INIS)

Freeman, J.T.; Mayes, M.; Wassmuth, F.; Taylor, K.; Rae, W.; Kuipers, F.

1997-01-01

The feasibility and cost effectiveness of surfactant-enhanced pumping to reduce source concentrations of petroleum hydrocarbons from contaminated soils was discussed. Light non-aqueous phase liquids (LNAPL) hydrocarbons are present beneath many petroleum production processing facilities in western Canada. Complete removal of LNAPLs from geologic materials is difficult and expensive. Treatment technologies include costly ex-situ methods such as excavation and in-situ methods such as physical extraction by soil venting and pumping, bioremediation, and combination methods such as bioventing, bioslurping or air sparging. Surfactant-aided pumping can reduce source hydrocarbon concentrations when used in conjunction with traditional pump and treat, or deep well injection. This study involved the selection of an appropriate surfactant from a wide variety of commercially available products. A site contaminated by hydrocarbons in Turner Valley, Alberta, was used for field scale testing. One of the major problems was quantifying the increase in the dissolved hydrocarbon concentrations in the recovered water once a surfactant was added. From the 30 surfactants screened in a series of washing and oil solubilization tests, two surfactants, Brij 97 and Tween 80, were selected for further evaluation. Increased hydrocarbon recovery was observed within 10 days of the introduction of the first surfactant. 2 refs., 7 figs

Contribution of Seawater Surfactants to Generated Primary Marine Aerosol Particles

Science.gov (United States)

Frossard, A. A.; Gerard, V.; Duplessis, P.; Kinsey, J. D.; Lu, X.; Zhu, Y.; Bisgrove, J.; Maben, J. R.; Long, M. S.; Chang, R.; Beaupre, S. R.; Kieber, D. J.; Keene, W. C.; Noziere, B.; Cohen, R. C.

2017-12-01

Surfactants account for minor fractions of total organic carbon in the ocean but may have major impacts on the surface tension of bursting bubbles at the sea surface that drive the production of primary marine aerosol particles (PMA). Surfactants associated with marine aerosol may also significantly reduce the surface tension of water thereby increasing the potential for cloud droplet activation and growth. During September and October 2016, PMA were produced from bursting bubbles in seawater using a high capacity generator at two biologically productive and two oligotrophic stations in the western North Atlantic, as part of a cruise on the R/V Endeavor. Surfactants were extracted from paired PMA and seawater samples, and their ionic compositions, total concentrations, and critical micelle concentrations (CMC) were quantified and compared for the four hydrographic stations. Higher surfactant concentrations were determined in the aerosol produced from biologically productive seawater compared to oligotrophic seawater, and the surfactants extracted from productive seawater were stronger (had lower CMCs) than those in the oligotrophic seawater. Surfactants associated with PMA and seawater in productive regions also varied over diel cycles, whereas those in the oligotrophic regions did not. This work demonstrates a direct link between surfactants in seawater and those in PMA.

Molecular docking studies of (1E,3E,5E)-1,6-Bis(substituted phenyl)hexa-1,3,5-triene and 1,4-Bis(substituted trans-styryl)benzene analogs as novel tyrosinase inhibitors.

Science.gov (United States)

Ha, Young Mi; Lee, Hye Jin; Park, Daeui; Jeong, Hyoung Oh; Park, Ji Young; Park, Yun Jung; Lee, Kyung Jin; Lee, Ji Yeon; Moon, Hyung Ryong; Chung, Hae Young

2013-01-01

We simulated the docking of the tertiary structure of mushroom tyrosinase with our compounds. From the structure-tyrosinase inhibitory activity relationship, it is notable that compounds 4, 8 and 11 showed similar or better activity rates than kojic acid which was used as a positive control. Compounds 17, 21, and 23 among benzene analogs that possess the same substituent showed significantly lower tyrosinase inhibitory effects. Therefore, we have confirmed that among the compounds showing better tyrosinase inhibitory effects than kojic acid, the compounds with triene analogs have better tyrosinase inhibitory effect than the compounds with benzene analogs. Docking simulation suggested the mechanism of compounds by several key residues which had possible hydrogen bonding interactions. The pharmacophore model underlined the features of active compounds, 4,4'-((1E,3E,5E)-hexa-1,3,5-triene-1,6-diyl)diphenol, 5,5'-((1E,3E,5E)-hexa-1,3,5-triene-1,6-diyl)bis(2-methoxy-phenol), and 5,5'-((1E,3E,5E)-hexa-1,3,5-triene-1,6-diyl)dibenzene-1,3-diol among triene derivatives which had several hydrogen bond groups on both terminal rings. The soundness of the docking results and the agreement with the pharmacophores suggest that it can be conveniently exploited to design inhibitors with an improved affinity for tyrosinase.

Adsorption of surfactants and polymers at interfaces

Science.gov (United States)

Rojas, Orlando Jose

Surface tension and high-resolution laser light scattering experiments were used to investigate the adsorption of isomeric sugar-based surfactants at the air/liquid interface in terms of surfactant surface packing and rheology. Soluble monolayers of submicellar surfactant solutions exhibited a relatively viscous behavior. It was also proved that light scattering of high-frequency thermally-induced capillary waves can be utilized to study surfactant exchange between the surface and the bulk solution. Such analysis revealed the existence of a diffusional relaxation mechanism. A procedure based on XPS was developed for quantification, on an absolute basis, of polymer adsorption on mica and Langmuir-Blodgett cellulose films. The adsorption of cationic polyelectrolytes on negatively-charged solid surfaces was highly dependent on the polymer ionicity. It was found that the adsorption process is driven by electrostatic mechanisms. Charge overcompensation (or charge reversal) of mica occurred after adsorption of polyelectrolytes of ca. 50% charge density, or higher. It was demonstrated that low-charge-density polyelectrolytes adsorb on solid surfaces with an extended configuration dominated by loops and tails. In this case the extent of adsorption is limited by steric constraints. The conformation of the polyelectrolyte in the adsorbed layer is dramatically affected by the presence of salts or surfactants in aqueous solution. The phenomena which occur upon increasing the ionic strength are consistent with the screening of the electrostatic attraction between polyelectrolyte segments and solid surface. This situation leads to polyelectrolyte desorption accompanied by both an increase in the layer thickness and the range of the steric force. Adsorbed polyelectrolytes and oppositely charged surfactants readily associate at the solid/liquid interface. Such association induces polyelectrolyte desorption at a surfactant concentration which depends on the polyelectrolyte charge

Nonlinear vibrational spectroscopy of surfactants at liquid interfaces

Science.gov (United States)

Miranda, Paulo Barbeitas

Surfactants are widely used to modify physical and chemical properties of interfaces. They play an important role in many technological problems. Surfactant monolayers are also of great scientific interest because they are two-dimensional systems that may exhibit a very rich phase transition behavior and can also be considered as a model system for biological interfaces. In this Thesis, we use a second-order nonlinear optical technique (Sum-Frequency Generation - SFG) to obtain vibrational spectra of surfactant monolayers at liquid/vapor and solid/liquid interfaces. The technique has several advantages: it is intrinsically surface-specific, can be applied to buried interfaces, has submonolayer sensitivity and is remarkably sensitive to the conformational order of surfactant monolayers. The first part of the Thesis is concerned with surfactant monolayers at the air/water interface (Langmuir films). Surface crystallization of an alcohol Langmuir film and of liquid alkanes are studied and their phase transition behaviors are found to be of different nature, although driven by similar intermolecular interactions. The effect of crystalline order of Langmuir monolayers on the interfacial water structure is also investigated. It is shown that water forms a well-ordered hydrogen-bonded network underneath an alcohol monolayer, in contrast to a fatty acid monolayer which induces a more disordered structure. In the latter case, ionization of the monolayer becomes more significant with increase of the water pH value, leading to an electric-field-induced ordering of interfacial water molecules. We also show that the orientation and conformation of fairly complicated molecules in a Langmuir monolayer can be completely mapped out using a combination of SFG and second harmonic generation (SHG). For a quantitative analysis of molecular orientation at an interface, local-field corrections must be included. The second part is a study of self-assembled surfactant monolayers at the

Respiratory Mechanics and Gas Exchange: The Effect of Surfactants

Science.gov (United States)

Jbaily, Abdulrahman; Szeri, Andrew J.

2017-11-01

The purpose of the lung is to exchange gases, primarily oxygen and carbon dioxide, between the atmosphere and the circulatory system. To enable this exchange, the airways in the lungs terminate in some 300 million alveoli that provide adequate surface area for transport. During breathing, work must be done to stretch various tissues to accommodate a greater volume of gas. Considerable work must also be done to expand the liquid lining (hypophase) that coats the interior surfaces of the alveoli. This is enabled by a surface active lipo-protein complex, known as pulmonary surfactant, that modifies the surface tension at the hypophase-air interface. Surfactants also serve as physical barriers that modify the rate of gas transfer across interfaces. We develop a mathematical model to study the action of pulmonary surfactant and its determinative contributions to breathing. The model is used to explore the influence of surfactants on alveolar mechanics and on gas exchange: it relates the work of respiration at the level of the alveolus to the gas exchange rate through the changing influence of pulmonary surfactant over the breathing cycle. This work is motivated by a need to develop improved surfactant replacement therapies to treat serious medical conditions.

Effects of magnetic pre-alignment of nano-powders on formation of high textured barium hexa-ferrite quasi-single crystals via a magnetic forming and liquid participation sintering route

International Nuclear Information System (INIS)

Liu, Junliang; Zeng, Yanwei; Zhang, Xingkai; Zhang, Ming

2015-01-01

Highly textured barium hexa-ferrite quasi-single crystal with narrow ferromagnetic resonance line-width is believed to be a potential gyromagnetic material for self-biased microwave devices. To fabricate barium hexa-ferrite quasi-single crystal with a high grain orientation degree, a magnetic forming and liquid participation sintering route has been developed. In this paper, the effects of the pre-alignment of the starting nano-powders on the formation of barium quasi-single crystal structures have been investigated. The results indicated that: the crystallites with large sizes and small specific surfaces were easily aligned for they got higher driving forces and lower resistances during magnetic forming. The average restricting magnetic field was about 4.647 kOe to overcome the average friction barrier between crystallites. The pre-aligned crystallites in magnetic forming acted as the “crystal seeds” for oriented growth of the un-aligned crystallites during liquid participation sintering to achieve a high grain orientation. To effectively promote the grain orientation degrees of the sintered pellets, the grain orientation degrees of the green compacts must be higher than a limited value of 15.0%. Barium hexa-ferrite quasi-single crystal with a high grain orientation degree of 98.6% was successfully fabricated after sintering the green compact with its grain orientation degree of 51.1%. - Highlights: • Aligned particles acted as “crystal seeds” for un-aligned ones' oriented growth. • Magnetic field of 4.647 kOe was needed to overcome crystallites' friction barrier. • GOD dramatically increased after sintering if starting GOD exceeded to 15.0%. • Quasi-single crystal was prepared by sintering green compact with GOD of 51.1%

Effects of magnetic pre-alignment of nano-powders on formation of high textured barium hexa-ferrite quasi-single crystals via a magnetic forming and liquid participation sintering route

Energy Technology Data Exchange (ETDEWEB)

Liu, Junliang, E-mail: liujunliang@yzu.edu.cn [Key Laboratory of Environmental Materials and Engineering of Jiangsu Province, School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002 (China); Zeng, Yanwei [State Key Laboratory of Materials-Oriented Chemical Engineering, School of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009 (China); Zhang, Xingkai [Key Laboratory of Environmental Materials and Engineering of Jiangsu Province, School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002 (China); Zhang, Ming [Key Laboratory of Environmental Materials and Engineering of Jiangsu Province, School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002 (China); Testing Center of Yangzhou University, Yangzhou 225002 (China)

2015-05-15

Highly textured barium hexa-ferrite quasi-single crystal with narrow ferromagnetic resonance line-width is believed to be a potential gyromagnetic material for self-biased microwave devices. To fabricate barium hexa-ferrite quasi-single crystal with a high grain orientation degree, a magnetic forming and liquid participation sintering route has been developed. In this paper, the effects of the pre-alignment of the starting nano-powders on the formation of barium quasi-single crystal structures have been investigated. The results indicated that: the crystallites with large sizes and small specific surfaces were easily aligned for they got higher driving forces and lower resistances during magnetic forming. The average restricting magnetic field was about 4.647 kOe to overcome the average friction barrier between crystallites. The pre-aligned crystallites in magnetic forming acted as the “crystal seeds” for oriented growth of the un-aligned crystallites during liquid participation sintering to achieve a high grain orientation. To effectively promote the grain orientation degrees of the sintered pellets, the grain orientation degrees of the green compacts must be higher than a limited value of 15.0%. Barium hexa-ferrite quasi-single crystal with a high grain orientation degree of 98.6% was successfully fabricated after sintering the green compact with its grain orientation degree of 51.1%. - Highlights: • Aligned particles acted as “crystal seeds” for un-aligned ones' oriented growth. • Magnetic field of 4.647 kOe was needed to overcome crystallites' friction barrier. • GOD dramatically increased after sintering if starting GOD exceeded to 15.0%. • Quasi-single crystal was prepared by sintering green compact with GOD of 51.1%.

Marangoni flows induced by non-uniform surfactant distributions

NARCIS (Netherlands)

Hanyak, M.

2012-01-01

The spreading dynamics of surfactants is of crucial importance for numerous technological applications ranging from printing and coating processes, pulmonary drug delivery to crude oil recovery. In the area of inkjet printing surfactants are necessary for lowering surface tension of water-based ink

Polymeric surfactants for enhanced oil recovery : A review

NARCIS (Netherlands)

Raffa, Patrizio; Broekhuis, Antonius A.; Picchioni, Francesco

Chemical enhanced oil recovery (EOR) is surely a topic of interest, as conventional oil resources become more scarce and the necessity of exploiting heavy and unconventional oils increases. EOR methods based on polymer flooding, surfactant-polymer flooding and alkali-surfactant-polymer flooding are

Reaction limited aggregation in surfactant-mediated epitaxy

Science.gov (United States)

Wu, Jing; Liu, Bang-Gui; Zhang, Zhenyu; Wang, E. G.

2000-05-01

A theoretical model for reaction limited aggregation (RLA) is introduced to study the effect of a monolayer of surfactant on the formation of two-dimensional islands in heteroepitaxial and homoepitaxial growth. In this model the basic atomic processes are considered as follows. A stable island consists of the adatoms that have exchanged positions with the surfactant atoms beneath them. Movable active adatoms may (a) diffuse on the surfactant terrace, (b) exchange positions with the surfactant atoms beneath them and become island seeds (seed exchange), or (c) stick to stable islands and become stuck but still active adatoms. The rate-limiting step for the formation of a stable island is the seed exchange. Furthermore, a stuck but still active adatom must overcome a sizable potential-energy barrier to exchange positions with the surfactant atom beneath it and become a member of the stable island (aided exchange). The seed exchange process can occur with an adatom or collectively with an addimer. In the case of dimer exchange, the diffusing adatoms on the surfactant terrace can meet and (after exchanging) form stable dimers, which can then become island seeds. Systematic kinetic Monte Carlo simulations and rate-equation analysis of the model are carried out. The key finding of these simulations is that a counterintuitive fractal-to-compact island shape transition can be induced either by increasing deposition flux or by decreasing growth temperature. This major qualitative conclusion is valid for both the monomer and the dimer seed exchanges and for two different substrate lattices (square and triangular, respectively), although there are some quantitative differences in the flux and temperature dependence of the island density. The shape transition observed is contrary to the prediction of the classic diffusion-limited aggregation (DLA) theory, but in excellent qualitative agreement with recent experiments. In rationalizing the main finding, it is crucial to realize

Evaporation kinetics of surfactant solution droplets on rice (Oryza sativa) leaves

Science.gov (United States)

Cao, Li-Dong; Zheng, Li; Xu, Jun; Li, Feng-Min; Huang, Qi-Liang

2017-01-01

The dynamics of evaporating sessile droplets on hydrophilic or hydrophobic surfaces is widely studied, and many models for these processes have been developed based on experimental evidence. However, few research has been explored on the evaporation of sessile droplets of surfactant or pesticide solutions on target crop leaves. Thus, in this paper the impact of surfactant concentrations on contact angle, contact diameter, droplet height, and evolution of the droplets’ evaporative volume on rice leaf surfaces have been investigated. The results indicate that the evaporation kinetics of surfactant droplets on rice leaves were influenced by both the surfactant concentrations and the hydrophobicity of rice leaf surfaces. When the surfactant concentration is lower than the surfactant CMC (critical micelle concentration), the droplet evaporation time is much longer than that of the high surfactant concentration. This is due to the longer existence time of a narrow wedge region under the lower surfactant concentration, and such narrow wedge region further restricts the droplet evaporation. Besides, our experimental data are shown to roughly collapse onto theoretical curves based on the model presented by Popov. This study could supply theoretical data on the evaporation of the adjuvant or pesticide droplets for practical applications in agriculture. PMID:28472108

Partitioning of hydrophobic pesticides within a soil-water-anionic surfactant system.

Science.gov (United States)

Wang, Peng; Keller, Arturo A

2009-02-01

Surfactants can be added to pesticide-contaminated soils to enhance the treatment efficiency of soil washing. Our results showed that pesticide (atrazine and diuron) partitioning and desorbability within a soil-water-anionic surfactant system is soil particle-size dependent and is significantly influenced by the presence of anionic surfactant. Anionic surfactant (linear alkylbenzene sulphonate, LAS) sorption was influenced by its complexation with both the soluble and exchangeable divalent cations in soils (e.g. Ca2+, Mg2+). In this study, we propose a new concept: soil system hardness which defines the total amount of soluble and exchangeable divalent cations associated with a soil. Our results showed that anionic surfactant works better with soils having lower soil system hardness. It was also found that the hydrophobic organic compounds (HOCs) sorbed onto the LAS-divalent cation precipitate, resulting in a significant decrease in the aqueous concentration of HOC. Our results showed that the effect of exchangeable cations and sorption of HOC onto the surfactant precipitates needs to be considered to accurately predict HOC behavior within soil-water-anionic surfactant systems.

Physicochemical treatments of anionic surfactants wastewater: Effect on aerobic biodegradability.

Science.gov (United States)

Aloui, Fathi; Kchaou, Sonia; Sayadi, Sami

2009-05-15

The effect of different physicochemical treatments on the aerobic biodegradability of an industrial wastewater resulting from a cosmetic industry has been investigated. This industrial wastewater contains 11423 and 3148mgL(-1) of chemical oxygen demand (COD) and anionic surfactants, respectively. The concentration of COD and anionic surfactants were followed throughout the diverse physicochemical treatments and biodegradation experiments. Different pretreatments of this industrial wastewater using chemical flocculation process with lime and aluminium sulphate (alum), and also advanced oxidation process (electro-coagulation (Fe and Al) and electro-Fenton) led to important COD and anionic surfactants removals. The best results were obtained using electro-Fenton process, exceeding 98 and 80% of anionic surfactants and COD removals, respectively. The biological treatment by an isolated strain Citrobacter braakii of the surfactant wastewater, as well as the pretreated wastewater by the various physicochemical processes used in this study showed that the best results were obtained with electro-Fenton pretreated wastewater. The characterization of the treated surfactant wastewater by the integrated process (electro-coagulation or electro-Fenton)-biological showed that it respects Tunisian discharge standards.

Adsorption and intercalation of anionic surfactants onto layered ...

Indian Academy of Sciences (India)

Layered double hydroxides (LDH) with brucite like structure was modified with various anionic surfactants containing sulfonate, carboxyl, phosphonate and sulfate end group through ion-exchange method. XRD reports indicated that the sulfonate group containing surfactants led to an adsorption process whereas the sulfate ...

Surfactant mediated liquid phase exfoliation of graphene

Science.gov (United States)

Narayan, Rekha; Kim, Sang Ouk

2015-10-01

Commercialization of graphene based applications inevitably requires cost effective mass production. From the early days of research on graphene, direct liquid phase exfoliation (LPE) of graphite has been considered as the most promising strategy to produce high-quality mono or few-layer graphene sheets in solvent dispersion forms. Substantial success has been achieved thus far in the LPE of graphene employing numerous solvent systems and suitable surfactants. This invited review article principally showcase the recent research progress as well as shortcomings of surfactant assisted LPE of graphene. In particular, a comprehensive assessment of the quality and yield of the graphene sheets produced by different categories of the surfactants are summarized. Future direction of LPE methods is also proposed for the eventual success of commercial applications.

Fullerene surfactants and their use in polymer solar cells

Science.gov (United States)

Jen, Kwan-Yue; Yip, Hin-Lap; Li, Chang-Zhi

2015-12-15

Fullerene surfactant compounds useful as interfacial layer in polymer solar cells to enhance solar cell efficiency. Polymer solar cell including a fullerene surfactant-containing interfacial layer intermediate cathode and active layer.

An arbitrary Lagrangian-Eulerian method for interfacial flows with insoluble surfactants

Science.gov (United States)

Yang, Xiaofeng

Interfacial flows, fluid flows involving two or more fluids that do not mix, are common in many natural and industrial processes such as rain drop formation, crude oil recovery, polymer blending, fuel spray formation, and so on. Surfactants (surface active substances) play an important role in such processes because they significantly change the interfacial dynamics. In this thesis, an arbitrary Lagrangian-Eulerian (ALE) method has been developed to numerically simulate interfacial flows with insoluble surfactants. The interface is captured using a coupled level set and volume of fluid method. To evolve the surfactant concentration, the method directly tracks the surfactant mass and the interfacial area. The surfactant concentration, which determines the local surface tension through an equation of state, is then computed as surfactant mass per interfacial area. By directly tracking the surfactant mass, the method conserves the surfactant mass exactly. To accurately approximate the interfacial area, the fluid interface is reconstructed using piecewise parabolas. The evolution of the level set function, volume fraction, interfacial area, and the surfactant mass is performed using an ALE approach. The fluid flow is governed by Stokes equations, which are solved using a finite element method. The surface forces are included in the momentum equation using a continuum surface stress formulation. To efficiently resolve the complex interfacial dynamics, interfacial regions of high surface curvature, and near contact regions between two interacting interfaces, the grid near the interface is adaptively refined. The method is extendible to axisymmetric and 3D spaces, and can be coupled with other flow solvers, such as Navier-Stokes and viscoelastic flow solvers, as well. The method has been applied to study the effect of surfactants on drop deformation and breakup in an extensional flow. Drop deformation results are compared with available experimental and theoretical

Surfactant Ligand Removal and Rational Fabrication of Inorganically Connected Quantum Dots

KAUST Repository

Zhang, Haitao; Hu, Bo; Sun, Liangfeng; Hovden, Robert; Wise, Frank W.; Muller, David A.; Robinson, Richard D.

2011-01-01

in that no new surfactant ligands are introduced and the post-treated NC surfaces are nearly bare. The detailed mechanism study shows that the high reactivity between (NH 4) 2S and metal-surfactant ligand complexes enables the complete removal of surfactant

Mutagenicity of diesel exhaust soot dispersed in phospholipid surfactants

Energy Technology Data Exchange (ETDEWEB)

Wallace, W.; Keane, M.; Xing, S.; Harrison, J.; Gautam, M.; Ong, T.

1994-06-01

Organics extractable from respirable diesel exhaust soot particles by organic solvents have been known for some time to be direct acting frameshift mutagens in the Ames Salmonella typhimurium histidine reversion assay. Upon deposition in a pulmonary alveolus or respiratory bronchiole, respirable diesel soot particles will contact first the hypophase which is coated by and laden with surfactants. To model interactions of soot and pulmonary surfactant, the authors dispersed soots in vitro in the primary phospholipid pulmonary surfactant dipalmitoyl glycerophosphorylcholine (lecithin) (DPL) in physiological saline. They have shown that diesel soots dispersed in lecithin surfactant can express mutagenic activity, in the Ames assay system using S. typhimurium TA98, comparable to that expressed by equal amounts of soot extracted by dichloromethane/dimethylsulfoxide (DCM/DMSO). Here the authors report additional data on the same system using additional exhaust soots and also using two other phospholipids, dipalmitoyl glycerophosphoryl ethanolamine (DPPE), and dipalmitoyl phosphatidic acid (DPPA), with different ionic character hydrophilic moieties. A preliminary study of the surfactant dispersed soot in an eucaryotic cell test system also is reported.

Surface rheology of surfactant solutions close to equilibrium

NARCIS (Netherlands)

Baets, P.J.M.; Stein, H.N.

1994-01-01

In this paper the authors present surface rheol. measurements of various surfactant solns. close to equil. in a Langmuir trough. The authors find that the storage modulus is, in the systems investigated, higher than the loss modulus. The rheol. behavior depends strongly on the surfactant concn.,

Theoretical and Simulations-Based Modeling of Micellization in Linear and Branched Surfactant Systems

Science.gov (United States)

Mendenhall, Jonathan D.

Surfactants are chemically-heterogeneous molecules possessing hydrophilic (head) and hydrophobic (tail) moieties. This dual nature of surfactants leads to interesting phase behavior in aqueous solution as a function of surfactant concentration, including: (i) formation of surfactant monolayers at surfaces and interfaces, and (ii) self-assembly into finite aggregates (micelles) in the bulk solution beyond the critical micelle concentration (cmc). This concentration-dependent phase behavior induces changes in solution properties. For example, the surface activity of surfactants can decrease the surface tension, and self-assembly in bulk solution can lead to changes in viscosity, equivalent conductivity, solubilization capacity, and other bulk properties. These effects make surfactants quite attractive and unique for use in product formulations, where they are utilized as detergents, dispersants, emulsifiers, solubilizers, surface and interfacial tension modifiers, and in other contexts. The specific chemical structure of the surfactant head and tail is essential in determining the overall performance properties of a surfactant in aqueous media. The surfactant tail drives the self-assembly process through the hydrophobic effect, while the surfactant head imparts a certain extent of solubility to the surfactant in aqueous solution through preferential interactions with the hydrogen-bonding network of water. The interplay between these two effects gives rise to the particular phase diagram of a surfactant, including the specific cmc at which micelles begin to form. In addition to serving as a quantitative indicator of micelle formation, the cmc represents a limit to surface monolayer formation, and hence to surface and interfacial tension reduction, because surfactant adsorption at interfaces remains approximately constant beyond the cmc. In addition, the cmc represents the onset of changes in bulk solution properties. This Thesis is concerned with the prediction of cmc

Phase transitions in surfactant monolayers

International Nuclear Information System (INIS)

Casson, B.D.

1998-01-01

Two-dimensional phase transitions have been studied in surfactant monolayers at the air/water interface by sum-frequency spectroscopy and ellipsometry. In equilibrium monolayers of medium-chain alcohols C n H 2n+1 OH (n = 9-14) a transition from a two-dimensional crystalline phase to a liquid was observed at temperatures above the bulk melting point. The small population of gauche defects in the solid phase increased only slightly at the phase transition. A model of the hydrocarbon chains as freely rotating rigid rods allowed the area per molecule and chain tilt in the liquid phase to be determined. The area per molecule, chain tilt and density of the liquid phase all increased with increasing chain length, but for each chain length the density was higher than in a bulk liquid hydrocarbon. In a monolayer of decanol adsorbed at the air/water interface a transition from a two-dimensional liquid to a gas was observed. A clear discontinuity in the coefficient of ellipticity as a function of temperature showed that the transition is first-order. This result suggests that liquid-gas phase transitions in surfactant monolayers may be more widespread than once thought. A solid-liquid phase transition has also been studied in mixed monolayers of dodecanol with an anionic surfactant (sodium dodecyl sulphate) and with a homologous series of cationic surfactants (alkyltrimethylammonium bromides: C n TABs, n = 12, 14, 16). The composition and structure of the mixed monolayers was studied above and below the phase transition. At low temperatures the mixed monolayers were as densely packed as a monolayer of pure dodecanol in its solid phase. At a fixed temperature the monolayers under-went a first-order phase transition to form a phase that was less dense and more conformationally disordered. The proportion of ionic surfactant in the mixed monolayer was greatest in the high temperature phase. As the chain length of the C n TAB increased the number of conformational defects

Surfactant nebulisation prevents the adverse effects of surfactant therapy on blood pressure and cerebral blood flow in rabbits with severe respiratory failure

NARCIS (Netherlands)

Dijk, Peter H.; Heikamp, A; Bambang Oetomo, Sidarto

1997-01-01

Objective: Surfactant replacement therapy for the neonatal respiratory distress syndrome has shown beneficial effects on lung function and survival. Recently, rapid fluctuations of haemodynamics and cerebral perfusion following surfactant instillation have beer, described and an association with the

(Cationic + nonionic) mixed surfactant aggregates for solubilisation of curcumin

International Nuclear Information System (INIS)

Kumar, Arun; Kaur, Gurpreet; Kansal, S.K.; Chaudhary, G.R.; Mehta, S.K.

2016-01-01

Highlights: • Critical micelle concentration of mixed surfactant has been measured. • Aqueous solubility and alkaline stability of curcumin has been significantly improved. • Location of curcumin within micelles has been evaluated. • Scavenging activity of curcumin has been improved. • Non-intercalative binding with ct-DNA has been observed. - Abstract: Curcumin is a potential drug for variety of diseases. Major limitations of curcumin are low water solubility, rapid hydrolytic degradation in alkaline medium and poor bioavailability. To overcome these limitations, highly potential mixed micellar system has been prepared. In order to reduce inter ionic repulsion and precipitation of surfactants, (cationic + non-ionic) mixed system have been chosen that directly influence its applicability. Hydrophobic chain of non-ionic surfactant significantly influences the cmc of mixed surfactant system as indicated by fluorescence and conductivity data. UV–visible spectroscopy analyses show that solubility, stability and antioxidant property of the curcumin is remarkably improved depending on cmc and aggregation number (N_a_g_g) of mixed surfactants, where N_a_g_g plays crucial role. Generally, curcumin undergoes complete degradation in slight basic medium, but stability has been maintained up to 8 h at pH-13 using formulated mixed micelles (only (20 to 25)% degraded). Location of curcumin which is monitored using emission spectroscopy, fluorescence quenching and "1H NMR spectroscopy techniques play the most important role. Observed results show that the major population of curcumin is located at the polar region and some are in hydrophobic region of the mixed micelles. To ensure the effect of mixed surfactants and curcumin loaded mixed surfactants on DNA, the interaction parameter indicates non-interclative interactions.

Dispersion of nanoparticulate suspensions using self-assembled surfactant aggregates

Science.gov (United States)

Singh, Pankaj Kumar

The dispersion of particles is critical for several industrial applications such as paints, inks, coatings, and cosmetics. Several emerging applications such as abrasives for precision polishing, and drug delivery systems are increasingly relying on nanoparticulates to achieve the desired performance. In the case of nanoparticles, the dispersion becomes more challenging because of the lack of fundamental understanding of dispersant adsorption and interparticle force prediction. Additionally, many of these processes use severe processing environments such as high normal forces (>100 mN/m), high shear forces (>10,000 s -1), and high ionic strengths (>0.1 M). Under such processing conditions, traditionally used dispersants based on electrostatics, and steric force repulsion mechanism may not be adequate. Hence, the development of optimally performing dispersants requires a fundamental understanding of the dispersion mechanism at the atomic/molecular scale. This study explores the use of self-assembled surfactant aggregates at the solid-liquid interface for dispersing nanoparticles in severe processing environments. Surfactant molecules can provide a feasible alternative to polymeric or inorganic dispersants for stabilizing ultrafine particles. The barrier to aggregation in the presence of surfactant molecules was measured using atomic force microscopy. The barrier heights correlated to suspension stability. To understand the mechanism for nanoparticulate suspension stability in the presence of surfactant films, the interface was characterized using zeta potential, contact angle, adsorption, and FT-IR (adsorbed surfactant film structure measurements). The effect of solution conditions such as pH and ionic strength on the suspension stability, and the self-assembled surfactant films was also investigated. It was determined that a transition from a random to an ordered orientation of the surfactant molecules at the interface was responsible for stability of

Impact of cationic surfactant on the self-assembly of sodium caseinate.

Science.gov (United States)

Vinceković, Marko; Curlin, Marija; Jurašin, Darija

2014-08-27

The impact of a cationic surfactant, dodecylammonium chloride (DDACl), on the self-assembly of sodium caseinate (SC) has been investigated by light scattering, zeta potential, and rheological measurements as well as by microscopy (transmission electron and confocal laser scanning microscopy). In SC dilute solutions concentration-dependent self-assembly proceeds through the formation of spherical associates and their aggregation into elongated structures composed of connected spheres. DDACl interacts with SC via its hydrophilic and hydrophobic groups, inducing changes in SC self-assembled structures. These changes strongly depend on the surfactant aggregation states (monomeric or micellar) as well as concentration ratio of both components, leading to the formation of soluble and insoluble complexes of nano- to microdimensions. DDACl monomers interact with SC self-assembled entities in a different way compared to their micelles. Surfactant monomers form soluble complexes (similar to surfactant mixed micelles) at lower SC concentration but insoluble gelatinous complexes at higher SC concentration. At surfactant micellar concentration soluble complexes with casein chains wrapped around surfactant micelles are formed. This study suggests that the use of proper cationic surfactant concentration will allow modification and control of structural changes of SC self-assembled entities.

Separation of oil and grease from oil sludge using surfactant

International Nuclear Information System (INIS)

Ainon Abdul Aziz; Syed Hakimi Sakuma Syed Ahmad; Zalina Laili

2005-01-01

The objective of the experiments was to observe the efficiency of the surfactant to remove oil and grease from oil sludges using various surfactant concentration ranging from 10 %, 15 %, 20 % and 30 %. The surfactant solution consists of two mixtures of Aqua 2000 and D Bond. The oil sludge were subjected to heating and surfactant treatment process. Remaining oil and grease concentration were observed on the oil sludges after treatment. Small scale experiments were conducted by heating process, without heating process and heating process with addition of sodium chloride. Surfactant solution was added in each process. Results shows that there is separation of oil and grease from the oil sludges. There were formation of mini emulsions (oil in water). The higher the concentration of surfactant used, the higher the concentrations of mini emulsion formed as observed. Solid remains after the treatment process were found to contain lesser oil concentration with presence of bitumen, sediment, organic and inorganic materials. After a washing process using distilled water, the solid was still black but less oily than before the treatment. There is no separation of oil occurred in aqueous solution for the control experiment. (Author)

New gluconamide-type cationic surfactants: Interactions with DNA and lipid membranes

Czech Academy of Sciences Publication Activity Database

Misiak, P.; Wilk, K. A.; Kral, Teresa; Wozniak, E.; Pruchnik, H.; Frackowiak, R.; Hof, Martin; Rózycka-Roszak, B.

180-181, OCT-NOV (2013), s. 44-54 ISSN 0301-4622 R&D Projects: GA ČR GBP208/12/G016 Institutional support: RVO:61388955 Keywords : Glucose-derived surfactant * Soft surfactant * Cationic surfactant Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.319, year: 2013

Use of surfactants in cleaning paraffin from oil wells

Energy Technology Data Exchange (ETDEWEB)

Liebold, G; Rehberg, W

1969-05-01

The use of surfactants is described especially oxethylated alkylphenols, in the cleaning of oil wells from paraffin. Aqueous 1 or 10% solutions of the surfactant were injected into the well through the annulus, partially in combination with demulsifiers (for example Separol-brands of BASF). Injection was accomplished continuously or in intervals; in the beginning of 50 ppm surfactant, afterward 15 to 30 ppm as related to the wet crude was necessary. Efficiency of the treatment could be proved by the decrease of pressure in the pipes, the loosening of paraffin shells, and considerably prolonged operation periods in wells which otherwise would have come to a standstill. In quite a number of wells, treatment with hot oil and electric heating could be completely replaced by injection of surfactants. (11 refs.)

Pulmonary Surfactants for Acute and Chronic Lung Diseases (Part II

Directory of Open Access Journals (Sweden)

O. A. Rozenberg

2014-01-01

Full Text Available Part 2 of the review considers the problem of surfactant therapy for acute respiratory distress syndrome (ARDS in adults and young and old children. It gives information on the results of surfactant therapy and prevention of ARDS in patients with severe concurrent trauma, inhalation injuries, complications due to complex expanded chest surgery, or severe pneumonias, including bilateral pneumonia in the presence of A/H1N1 influenza. There are data on the use of a surfactant in obstetric care and prevention of primary graft dysfunction during lung transplantation. The results of longterm use of surfactant therapy in Russia, suggesting that death rates from ARDS may be substantially reduced (to 20% are discussed. Examples of surfactant therapy for other noncritical lung diseases, such as permanent athelectasis, chronic obstructive pulmonary diseases, and asthma, as well tuberculosis, are also considered.

Structure-function relationships in pulmonary surfactant membranes: from biophysics to therapy.

Science.gov (United States)

Lopez-Rodriguez, Elena; Pérez-Gil, Jesús

2014-06-01

Pulmonary surfactant is an essential lipid-protein complex to maintain an operative respiratory surface at the mammalian lungs. It reduces surface tension at the alveolar air-liquid interface to stabilise the lungs against physical forces operating along the compression-expansion breathing cycles. At the same time, surfactant integrates elements establishing a primary barrier against the entry of pathogens. Lack or deficiencies of the surfactant system are associated with respiratory pathologies, which treatment often includes supplementation with exogenous materials. The present review summarises current models on the molecular mechanisms of surfactant function, with particular emphasis in its biophysical properties to stabilise the lungs and the molecular alterations connecting impaired surfactant with diseased organs. It also provides a perspective on the current surfactant-based strategies to treat respiratory pathologies. This article is part of a Special Issue entitled: Membrane Structure and Function: Relevance in the Cell's Physiology, Pathology and Therapy. Copyright © 2014 Elsevier B.V. All rights reserved.

Molecular dynamics simulations of surfactant and nanoparticle self-assembly at liquid-liquid interfaces

Energy Technology Data Exchange (ETDEWEB)

Luo Mingxiang; Dai, Lenore L [Department of Chemical Engineering, Texas Tech University, Lubbock, TX 79409 (United States)

2007-09-19

We have performed molecular dynamics (MD) simulations to investigate self-assembly at water-trichloroethylene (TCE) interfaces with the emphasis on systems containing modified hydrocarbon nanoparticles (1.2 nm in diameter) and sodium dodecyl sulfate (SDS) surfactants. The nanoparticles and surfactants were first distributed randomly in the water phase. The MD simulations have clearly shown the progress of migration and final equilibrium of the SDS molecules at the water-TCE interfaces with the nanoparticles either at or in the vicinity of the interfaces. One unique feature is the 'attachment' of surfactant molecules to the nanoparticle clusters in the water phase followed by the 'detachment' at the water-TCE interfaces. At low concentrations of surfactants, the surfactants and nanoparticles co-equilibrate at the interfaces. However, the surfactants, at high concentrations, competitively dominate the interfaces and deplete nanoparticles away from the interfaces. The interfacial properties, such as interfacial thickness and interfacial tension, are significantly influenced by the presence of the surfactants, but not the nanoparticles. The order of the surfactants at the interfaces increases with increasing surfactant concentration, but is independent of nanoparticle concentration. Finally, the simulation has shown that surfactants can aggregate along the water-TCE interfaces, with and without the presence of nanoparticles.

Preparation of nanocrystalline MgO by surfactant assisted precipitation method

International Nuclear Information System (INIS)

Rezaei, Mehran; Khajenoori, Majid; Nematollahi, Behzad

2011-01-01

Highlights: → Nanocrystalline magnesium oxide with high surface area. → MgO prepared with surfactant showed different morphologies compared with the sample prepared without surfactant. → MgO prepared with surfactant showed a plate-like shape. → Refluxing temperature and time and the surfactant to metal molar ratio affect the textural properties of MgO. -- Abstract: Nanocrystalline magnesium oxide with high surface area was prepared by a simple precipitation method using pluronic P123 triblock copolymer (Poly (ethylene glycol)-block, Poly (propylene glycol)-block, Poly (ethylene glycol)) as surfactant and under refluxing conditions. The prepared samples were characterized by X-ray diffraction (XRD), N 2 adsorption (BET) and scanning and transmission electron microscopies (SEM and TEM). The obtained results revealed that the refluxing time and temperature and the molar ratio of surfactant to metal affect the structural properties of MgO, because of the changes in the rate and extent of P123 adsorption on the prepared samples. The results showed that the addition of surfactant is effective to prepare magnesium oxide with high surface area and affects the morphology of the prepared samples. With increasing the P123/MgO molar ratio to 0.05 the pore size distribution was shifted to larger size. The sample prepared with addition of surfactant showed a plate-like shape which was completely different with the morphology of the sample prepared without surfactant. The formation of nanoplate-like MgO was related to higher surface density of Mg ions on the (0 0 1) plane than that on the other planes of the Mg(OH) 2 crystal. The (0 0 1) plane would be blocked preferentially by the adsorbed P123 molecules during the growing process of Mg(OH) 2 nanoentities and the growth on the (0 0 1) plane would be markedly restricted, and the consequence is the generation of nanoplate-like MgO. In addition, increase in refluxing temperature and time increased the specific surface area

Preparation of nanocrystalline MgO by surfactant assisted precipitation method

Energy Technology Data Exchange (ETDEWEB)

Rezaei, Mehran, E-mail: rezaei@kashanu.ac.ir [Catalyst and Advanced Materials Research Laboratory, Chemical Engineering Department, Faculty of Engineering, University of Kashan, Kashan (Iran, Islamic Republic of); Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan (Iran, Islamic Republic of); Khajenoori, Majid; Nematollahi, Behzad [Catalyst and Advanced Materials Research Laboratory, Chemical Engineering Department, Faculty of Engineering, University of Kashan, Kashan (Iran, Islamic Republic of)

2011-10-15

Highlights: {yields} Nanocrystalline magnesium oxide with high surface area. {yields} MgO prepared with surfactant showed different morphologies compared with the sample prepared without surfactant. {yields} MgO prepared with surfactant showed a plate-like shape. {yields} Refluxing temperature and time and the surfactant to metal molar ratio affect the textural properties of MgO. -- Abstract: Nanocrystalline magnesium oxide with high surface area was prepared by a simple precipitation method using pluronic P123 triblock copolymer (Poly (ethylene glycol)-block, Poly (propylene glycol)-block, Poly (ethylene glycol)) as surfactant and under refluxing conditions. The prepared samples were characterized by X-ray diffraction (XRD), N{sub 2} adsorption (BET) and scanning and transmission electron microscopies (SEM and TEM). The obtained results revealed that the refluxing time and temperature and the molar ratio of surfactant to metal affect the structural properties of MgO, because of the changes in the rate and extent of P123 adsorption on the prepared samples. The results showed that the addition of surfactant is effective to prepare magnesium oxide with high surface area and affects the morphology of the prepared samples. With increasing the P123/MgO molar ratio to 0.05 the pore size distribution was shifted to larger size. The sample prepared with addition of surfactant showed a plate-like shape which was completely different with the morphology of the sample prepared without surfactant. The formation of nanoplate-like MgO was related to higher surface density of Mg ions on the (0 0 1) plane than that on the other planes of the Mg(OH){sub 2} crystal. The (0 0 1) plane would be blocked preferentially by the adsorbed P123 molecules during the growing process of Mg(OH){sub 2} nanoentities and the growth on the (0 0 1) plane would be markedly restricted, and the consequence is the generation of nanoplate-like MgO. In addition, increase in refluxing temperature and time

Tuning metal–carboxylate coordination in crystalline metal–organic frameworks through surfactant media

Energy Technology Data Exchange (ETDEWEB)

Gao, Junkuo [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Ye, Kaiqi [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012 (China); He, Mi [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Xiong, Wei-Wei; Cao, Wenfang; Lee, Zhi Yi [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Wang, Yue [State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012 (China); Wu, Tom [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Huo, Fengwei [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Liu, Xiaogang [Department of Chemistry, National University of Singapore, Singapore 117543 (Singapore); Institute of Materials Research Engineering, Agency for Science, Technology and Research, Singapore 117602 (Singapore); Zhang, Qichun, E-mail: qczhang@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

2013-10-15

Although it has been widely demonstrated that surfactants can efficiently control the size, shape and surface properties of micro/nanocrystals of metal–organic frameworks (MOFs) due to the strong interactions between surfactants and crystal facets of MOFs, the use of surfactants as reaction media to grow MOF single crystals is unprecedented. In addition, compared with ionic liquids, surfactants are much cheaper and can have multifunctional properties such as acidic, basic, neutral, cationic, anionic, or even block. These factors strongly motivate us to develop a new synthetic strategy: growing crystalline MOFs in surfactants. In this report, eight new two-dimensional (2D) or three-dimensional (3D) MOFs have been successfully synthesized in an industrially-abundant and environmentally-friendly surfactant: polyethylene glycol-200 (PEG-200). Eight different coordination modes of carboxylates, ranging from monodentate η{sup 1} mode to tetra-donor coordination µ{sub 3}-η{sup 1}:η{sup 2}:η{sup 1} mode, have been founded in our research. The magnetic properties of Co-based MOFs were investigated and MOF NTU-Z6b showed a phase transition with a Curie temperature (T{sub c}) at 5 K. Our strategy of growing crystalline MOFs in surfactant could offer exciting opportunities for preparing novel MOFs with diverse structures and interesting properties. - Graphical abstract: Surfactants have been used as reaction media to grow MOF single crystals for the first time. Eight new two-dimensional or three-dimensional MOFs were successfully synthesized in surfactant polyethylene glycol-200 (PEG-200). Coordination modes of carboxylates up to eight were founded. Our strategy of growing crystalline MOFs in surfactant could offer exciting opportunities for preparing novel MOFs with diverse structures and interesting properties. Display Omitted - Highlights: • Surfactant-thermal synthesis of crystalline metal–organic frameworks. • Eight new 2-D or 3-D metal–organic frameworks

A simplified treatment of surfactant effects on cloud drop activation

Directory of Open Access Journals (Sweden)

T. Raatikainen

2011-02-01

Full Text Available Dissolved surface active species, or surfactants, have a tendency to partition to solution surface and thereby decrease solution surface tension. Activating cloud droplets have large surface-to-volume ratios, and the amount of surfactant molecules in them is limited. Therefore, unlike with macroscopic solutions, partitioning to the surface can effectively deplete the droplet interior of surfactant molecules.

Surfactant partitioning equilibrium for activating cloud droplets has so far been solved numerically from a group of non-linear equations containing the Gibbs adsorption equation coupled with a surface tension model and an optional activity coefficient model. This can be a problem when surfactant effects are examined by using large-scale cloud models. Namely, computing time increases significantly due to the partitioning calculations done in the lowest levels of nested iterations.

Our purpose is to reduce the group of non-linear equations to simple polynomial equations with well known analytical solutions. In order to do that, we describe surface tension lowering using the Szyskowski equation, and ignore all droplet solution non-idealities. It is assumed that there is only one surfactant exhibiting bulk-surface partitioning, but the number of non-surfactant solutes is unlimited. It is shown that the simplifications cause only minor errors to predicted bulk solution concentrations and cloud droplet activation. In addition, computing time is decreased at least by an order of magnitude when using the analytical solutions.

Flow improvers for water injection based on surfactants

Energy Technology Data Exchange (ETDEWEB)

Oskarsson, H.; Uneback, I.; Hellsten, M.

2006-03-15

In many cases it is desirable to increase the flow of injection water when an oil well deteriorates. It is very costly in offshore operation to lay down an additional water pipe to the injection site. Flow improvers for the injection water will thus be the most cost-effective way to increase the flow rate. During the last years water-soluble polymers have also been applied for this purpose. These drag-reducing polymers are however only slowly biodegraded which has been an incentive for the development of readily biodegradable surfactants as flow improvers for injection water. A combination of a zwitterionic and an anionic surfactant has been tested in a 5.5 inch, 700 m long flow loop containing sulphate brine with salinity similar to sea water. A drag reduction between 75 and 80% was achieved with 119 ppm in solution of the surfactant blend at an average velocity of 1.9 m/s and between 50 and 55% at 2.9 m/s. The surfactants in this formulation were also found to be readily biodegradable in sea water and low bio accumulating which means they have an improved environmental profile compared to the polymers used today. Due to the self-healing properties of the drag-reducing structures formed by surfactants, these may be added before the pump section - contrary to polymers which are permanently destroyed by high shear forces. (Author)

Synthesis of mesoporous nano-hydroxyapatite by using zwitterions surfactant

Science.gov (United States)

Mesoporous nano-hydroxyapatite (mn-HAP) was successfully synthesized via a novel micelle-templating method using lauryl dimethylaminoacetic acid as zwitterionic surfactant. The systematic use of such a surfactant in combination with microwave energy inputenables the precise contr...

Effects of concentration, head group, and structure of surfactants on the degradation of phenanthrene

International Nuclear Information System (INIS)

Jin Danyue; Jiang Xia; Jing Xin; Ou Ziqing

2007-01-01

The effects of concentration, polar/ionic head group, and structure of surfactants on the biodegradation of polycyclic aromatic hydrocarbons (PAHs) in the aqueous phase, as well as their effects on the bacterial activity were investigated. The toxicity ranking of studied surfactants is: non-ionic surfactants (Tween 80, Brij30, 10LE and Brij35) -1 ) served the sole carbon and energy resource. However, the degradation of 14 C-phenanthrene showed either a decrease or no obvious change with the surfactants present at all tested concentrations (5-40 mg L -1 ). Thus, the surfactant addition is not beneficial to the removal of phenanthrene or other PAH contaminants due presumably to the preferential utilization of surfactants at low levels as the non-toxic nutrient resource and to the high toxicity of the surfactants at high levels to the microorganism activity. Biodegradation of phenanthrene was also influenced by the surfactant concentration, head group type, and structure. Much more research has yet to be completed on the use of surfactants for soil remediation due to the surfactant toxicity or biodegradation effect

Systems of mechanized and reactive droplets powered by multi-responsive surfactants

Science.gov (United States)

Yang, Zhijie; Wei, Jingjing; Sobolev, Yaroslav I.; Grzybowski, Bartosz A.

2018-01-01

Although ‘active’ surfactants, which are responsive to individual external stimuli such as temperature, electric or magnetic fields, light, redox processes or chemical agents, are well known, it would be interesting to combine several of these properties within one surfactant species. Such multi-responsive surfactants could provide ways of manipulating individual droplets and possibly assembling them into larger systems of dynamic reactors. Here we describe surfactants based on functionalized nanoparticle dimers that combine all of these and several other characteristics. These surfactants and therefore the droplets that they cover are simultaneously addressable by magnetic, optical and electric fields. As a result, the surfactant-covered droplets can be assembled into various hierarchical structures, including dynamic ones, in which light powers the rapid rotation of the droplets. Such rotating droplets can transfer mechanical torques to their non-nearest neighbours, thus acting like systems of mechanical gears. Furthermore, droplets of different types can be merged by applying electric fields and, owing to interfacial jamming, can form complex, non-spherical, ‘patchy’ structures with different surface regions covered with different surfactants. In systems of droplets that carry different chemicals, combinations of multiple stimuli can be used to control the orientations of the droplets, inter-droplet transport, mixing of contents and, ultimately, sequences of chemical reactions. Overall, the multi-responsive active surfactants that we describe provide an unprecedented level of flexibility with which liquid droplets can be manipulated, assembled and reacted.

Evaluation of a common commercial surfactant in a water recycle system

International Nuclear Information System (INIS)

Rector, T.; Jackson, A.; Rainwater, K.; Pickering, S.

2002-01-01

The fate of a common commercial surfactant was investigated in the biological reactors of a water recycle system. A NO 2 - reducing packed-bed bioreactor was employed to evaluate degradation of surfactant present in a typical greywater stream. The research was conducted to determine if an alternative commercial surfactant could be used in a biological water recycle system proposed for space travel in place of the current surfactant. The commercial soap used in the research was Pert Plus for Kids (PPK), which contains sodium laureth sulfate (SLES) as the active surfactant. Experiments included a combination of microcosm studies as well as a continuous-flow packed-bed bioreactor. The hydraulic retention time of the packed-bed bioreactor was varied through changes in flow rate to yield different steady-state values for NO 2 -N, TOC, and COD. Steady-state values will allow the determination of the bacterial kinetic parameters. Initial results suggest that the commercial surfactant may be difficult to treat in the time frame of typical biological systems. NO 2 - reduction was favorable in the packed-bed reactor, but TOC removal rates did not correspond to the NO 2 - removal. It is theorized that, due to its high K oc value (1200), SLES has an affinity to absorb to the media contained in the bed, which in turn allows for adsorption of the surfactant. Future research will include development of an isotherm model to characterize the adsorption rates and correlate them to surfactant removal. (author)

Safety assessment of decyl glucoside and other alkyl glucosides as used in cosmetics.

Science.gov (United States)

Fiume, Monice M; Heldreth, Bart; Bergfeld, Wilma F; Belsito, Donald V; Hill, Ronald A; Klaassen, Curtis D; Liebler, Daniel; Marks, James G; Shank, Ronald C; Slaga, Thomas J; Snyder, Paul W; Andersen, F Alan

2013-01-01

The Cosmetic Ingredient Review (CIR) Expert Panel assessed the safety of 19 alkyl glucosides as used in cosmetics and concluded that these ingredients are safe in the present practices of use and concentration when formulated to be nonirritating. Most of these ingredients function as surfactants in cosmetics, but some have additional functions as skin-conditioning agents, hair-conditioning agents, or emulsion stabilizers. The Panel reviewed the available animal and clinical data on these ingredients. Since glucoside hydrolases in human skin are likely to break down these ingredients to release their respective fatty acids and glucose, the Panel also reviewed CIR reports on the safety of fatty alcohols and were able to extrapolate data from those previous reports to support safety.

Numerical approach for enhanced oil recovery with surfactant flooding

Directory of Open Access Journals (Sweden)

Sadegh Keshtkar

2016-03-01

Full Text Available The remained oil in the reservoir after conventional water-flooding processes, forms a dispersed phase in the form of oil drops which is trapped by capillary forces and is almost about 70% of the original oil in the place (OOIP. To reduce oil residual saturation in laboratory experiments and field projects, surfactant flooding is effective via decreasing the interfacial tension mobility ratio between oil and water phases. Estimation of the role of design variables, like chemical concentrations, partition coefficient and injection rate in different performance quantities, considering a heterogeneous and multiphase oil reservoir is a critical stage for optimal design. Increasing demand for oil production from water-flooded reservoirs has caused an increasing interest in surfactant-polymer (SP and alkali-surfactant-polymer (ASP. Modeling minimizes the risk of high cost of chemicals by improving our insight of process. In the present paper, a surfactant compositional flood model for a three-component (water, petroleum and surfactant, two phase (aqueous and oleic system is studied. A homogeneous, two-dimensional, isothermal reservoir with no free gas or alkali is assumed. The governing equations are in three categories: the continuity equations for the transport of each component, Darcy's equation for the transport of each phase and other auxiliary equations. The equations are solved by finite-differences using a procedure implicit in pressure and explicit in saturation. The validation of the model is achieved through comparing the modeling results with CMG simulators and Buckley–Leverett theory. The results of modeling showed good agreement with CMG results, and the comparison with Buckley–Leverett theory is explained according to different assumptions. After validation of the model, in order to investigate sensitivity analysis, the effects of system variables (partition coefficient, surface tension, oil viscosity and surface injection

Performance improvement of ionic surfactant flooding in carbonate rock samples by use of nanoparticles

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Mohammad Ali Ahmadi

2016-07-01

Full Text Available Abstract Various surfactants have been used in upstream petroleum processes like chemical flooding. Ultimately, the performance of these surfactants depends on their ability to reduce the interfacial tension between oil and water. The surfactant concentration in the aqueous solution decreases owing to the loss of the surfactant on the rock surface in the injection process. The main objective of this paper is to inhibit the surfactant loss by means of adding nanoparticles. Sodium dodecyl sulfate and silica nanoparticles were used as ionic surfactant and nanoparticles in our experiments, respectively. AEROSIL® 816 and AEROSIL® 200 are hydrophobic and hydrophilic nanoparticles. To determine the adsorption loss of the surfactant onto rock samples, a conductivity approach was used. Real carbonate rock samples were used as the solid phase in adsorption experiments. It should be noted that the rock samples were water wet. This paper describes how equilibrium adsorption was investigated by examining adsorption behavior in a system of carbonate sample (solid phase and surfactant solution (aqueous phase. The initial surfactant and nanoparticle concentrations were 500–5000 and 500–2000 ppm, respectively. The rate of surfactant losses was extremely dependent on the concentration of the surfactant in the system, and the adsorption of the surfactant decreased with an increase in the nanoparticle concentration. Also, the hydrophilic nanoparticles are more effective than the hydrophobic nanoparticles.

Nonlinear dynamics in experimental devices with compressed/expanded surfactant monolayers

International Nuclear Information System (INIS)

Higuera, M; Perales, J M; Vega, J M

2014-01-01

A theory is provided for a common experimental set up that is used to measure surface properties in surfactant monolayers. The set up consists of a surfactant monolayer (over a shallow liquid layer) that is compressed/expanded in a periodic fashion by moving in counter-phase two parallel, slightly immersed solid barriers, which vary the free surface area and thus the surfactant concentration. The simplest theory ignores the fluid dynamics in the bulk fluid, assuming spatially uniform surfactant concentration, which requires quite small forcing frequencies and provides reversible dynamics in the compression/expansion cycles. In this paper, we present a long-wave theory for not so slow oscillations that assumes local equilibrium but takes the fluid dynamics into account. This simple theory uncovers the physical mechanisms involved in the surfactant behavior and allows for extracting more information from each experimental run. The conclusion is that the fluid dynamics cannot be ignored, and that some irreversible dynamics could well have a fluid dynamic origin. (paper)

The interactions between ionic surfactants and phosphatidylcholine vesicles: Conductometry

Science.gov (United States)

Tsao, Heng-Kwong; Tseng, Wen Liang

2001-11-01

The interaction between ionic surfactants and phosphatidylcholine vesicles, which are prepared without addition of buffer and salt, is investigated by conductivity measurements. On the basis of the vesicle acting as a trap of charge carriers, the bilayer/aqueous phase partition coefficient K and the surfactant/lipid molar ratio Re of nine surfactants are determined. The thermodynamic consistency is satisfied by the measured parameters. The effects of the alkyl chain length (C10-C16) and ionic head group are then studied. The inverse partition coefficient K-1 is linearly related to the critical micelle concentration. The solubilizing ability Reb is a consequence of the competition between the surfactant incorporation into the bilayer and the formation of micelles. Consequently, the K parameter rises whereas the Reb parameter declines as the chain length is increased. The influence due to addition of salt is also discussed.

Practical Considerations and Challenges Involved in Surfactant Enhanced Bioremediation of Oil

Directory of Open Access Journals (Sweden)

Sagarika Mohanty

2013-01-01

Full Text Available Surfactant enhanced bioremediation (SEB of oil is an approach adopted to overcome the bioavailability constraints encountered in biotransformation of nonaqueous phase liquid (NAPL pollutants. Fuel oils contain n-alkanes and other aliphatic hydrocarbons, monoaromatics, and polynuclear aromatic hydrocarbons (PAHs. Although hydrocarbon degrading cultures are abundant in nature, complete biodegradation of oil is rarely achieved even under favorable environmental conditions due to the structural complexity of oil and culture specificities. Moreover, the interaction among cultures in a consortium, substrate interaction effects during the degradation and ability of specific cultures to alter the bioavailability of oil invariably affect the process. Although SEB has the potential to increase the degradation rate of oil and its constituents, there are numerous challenges in the successful application of this technology. Success is dependent on the choice of appropriate surfactant type and dose since the surfactant-hydrocarbon-microorganism interaction may be unique to each scenario. Surfactants not only enhance the uptake of constituents through micellar solubilization and emulsification but can also alter microbial cell surface characteristics. Moreover, hydrocarbons partitioned in micelles may not be readily bioavailable depending on the microorganism-surfactant interactions. Surfactant toxicity and inherent biodegradability of surfactants may pose additional challenges as discussed in this review.

Practical Considerations and Challenges Involved in Surfactant Enhanced Bioremediation of Oil

Science.gov (United States)

Mohanty, Sagarika; Jasmine, Jublee

2013-01-01

Surfactant enhanced bioremediation (SEB) of oil is an approach adopted to overcome the bioavailability constraints encountered in biotransformation of nonaqueous phase liquid (NAPL) pollutants. Fuel oils contain n-alkanes and other aliphatic hydrocarbons, monoaromatics, and polynuclear aromatic hydrocarbons (PAHs). Although hydrocarbon degrading cultures are abundant in nature, complete biodegradation of oil is rarely achieved even under favorable environmental conditions due to the structural complexity of oil and culture specificities. Moreover, the interaction among cultures in a consortium, substrate interaction effects during the degradation and ability of specific cultures to alter the bioavailability of oil invariably affect the process. Although SEB has the potential to increase the degradation rate of oil and its constituents, there are numerous challenges in the successful application of this technology. Success is dependent on the choice of appropriate surfactant type and dose since the surfactant-hydrocarbon-microorganism interaction may be unique to each scenario. Surfactants not only enhance the uptake of constituents through micellar solubilization and emulsification but can also alter microbial cell surface characteristics. Moreover, hydrocarbons partitioned in micelles may not be readily bioavailable depending on the microorganism-surfactant interactions. Surfactant toxicity and inherent biodegradability of surfactants may pose additional challenges as discussed in this review. PMID:24350261

Nanocomposites of PP and bentonite clay modified with different surfactants

International Nuclear Information System (INIS)

Rodrigues, Andre W.B.; Agrawal, Pankaj; Araujo, Edcleide M.; Melo, Tomas J.A.; Ueki, Marcelo M.

2009-01-01

The aim of this work was the development of nano composites of polypropylene (PP) and national bentonite clay modified with different surfactants. The results of X-Ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) showed that the organophilization process was effective. The surfactants led to a significant increase in the basal spacing of Brasgel PA clay. XRD results of the mixture PP/Brasgel PA clay modified with Praepagem WB surfactant indicated that a nanocomposite with intercalated structure was formed. When the Brasgel PA clay was modified with Praepagem HY surfactant, DRX results indicated that a micro composite was formed. Screw speed, clay content and PP viscosity had no influence on the XRD pattern of the obtained materials. (author)

Factors controlling leaching of polycyclic aromatic hydrocarbons from petroleum source rock using nonionic surfactant

Energy Technology Data Exchange (ETDEWEB)

Akinlua, Akinsehinwa [Obafemi Awolowo Univ., Ile-Ife (Nigeria). Fossil Fuels and Environmental Geochemistry Group; Jochmann, Maik A.; Qian, Yuan; Schmidt, Torsten C. [Duisburg-Essen Univ., Essen (Germany). Instrumental Analytical Chemistry; Sulkowski, Martin [Duisburg-Essen Univ., Essen (Germany). Inst. of Environmental Analytical Chemistry

2012-03-15

The extraction of polycyclic aromatic hydrocarbons (PAHs) from petroleum source rock by nonionic surfactants with the assistance of microwave irradiation was investigated and the conditions for maximum yield were determined. The results showed that the extraction temperatures and type of surfactant have significant effects on extraction yields of PAHs. Factors such as surfactant concentration, irradiation power, sample/solvent ratio and mixing surfactants (i.e., mixture of surfactant at specific ratio) also influence the extraction efficiencies for these compounds. The optimum temperature for microwave-assisted nonionic surfactant extraction of PAHs from petroleum source rock was 120 C and the best suited surfactant was Brij 35. The new method showed extraction efficiencies comparable to those afforded by the Soxhlet extraction method, but a reduction of the extraction times and environmentally friendliness of the new nonionic surfactant extraction system are clear advantages. The results also show that microwave-assisted nonionic surfactant extraction is a good and efficient green analytical preparatory technique for geochemical evaluation of petroleum source rock. (orig.)

N-Decyl-S-trityl-(R)-cysteine, a new chiral selector for "green" ligand-exchange chromatography applications.

Science.gov (United States)

Carotti, Andrea; Ianni, Federica; Camaioni, Emidio; Pucciarini, Lucia; Marinozzi, Maura; Sardella, Roccaldo; Natalini, Benedetto

2017-09-10

In search for new enantioselectivity profiles, the N-decyl-S-trityl-(R)-cysteine [C 10 -(R)-STC] was synthesized through a one-step procedure and then hydrophobically adsorbed onto an octadecylsilica surface to generate a stable chiral stationary phase for ligand-exchange chromatography (CLEC-CSP) applications. The CLEC analysis was carried out on underivatized amino acids, by using a Cu(II) sulphate (1.0mM) containing aqueous eluent system. Most of the analysed compounds (34 out of 45) were enantiodiscriminated by the C 10 -(R)-STC-based CSP, with resolution factor (R S ) values up to 8.86. Conformationally rigid and hydrophobic ligands often experienced the largest enantioselectivity effects. A high loadability emerged from the analysis of rac-NorVal (selected as prototype test compound): up to 20mg/mL were efficiently enantioseparated with the CLEC-CSP. Two in-line hand-made cartridges filled with a strong cation-exchange resin allowed the effective catching of Cu(II) ions after the semi-preparative enantioseparation. The quantitative recovery of the rac-NorVal enantiomers was made possible by flowing through the cartridge a 5% (v) ammonia solution. The CLEC phase proved successful in the enantioselective analysis of a commercially available (S)-Leu containing tablet. Furthermore, in order to understand the molecular basis for a successful use of the C 10 -(R)-STC-based CLEC system, a descriptive structure-separation relationship study was performed. As a result, all compounds with a MEAN-QPlogS (a hydrophilicity descriptor) value lower than 0.373 can be most likely enantioseparated with the CLEC system under investigation. In the work, the numerous aspects complying with the principles of green chromatography are highlighted and discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of Surfactants on Mechanical, Thermal, and Photostability of a Monoclonal Antibody.

Science.gov (United States)

Agarkhed, Meera; O'Dell, Courtney; Hsieh, Ming-Ching; Zhang, Jingming; Goldstein, Joel; Srivastava, Arvind

2018-01-01

The purpose of this work was to evaluate the effect of commonly used surfactants (at 0.01% w/v concentration) on mechanical, thermal, and photostability of a monoclonal antibody (MAb1) of IgG1 sub-class and to evaluate the minimum concentration of surfactant (Polysorbate 80) required in protecting MAb1 from mechanical stress. Surfactants evaluated were non-ionic surfactants, Polysorbate 80, Polysorbate 20, Pluronic F-68 (polyoxyethylene-polyoxypropylene block polymer), Brij 35 (polyoxyethylene lauryl ether), Triton X-100, and an anionic surfactant, Caprylic acid (1-Heptanecarboxylic acid). After evaluating effect of surfactants and determining stabilizing effect of Polysorbate 80 against mechanical stress without compromising thermal and photostability of MAb1, the minimum concentration of Polysorbate 80 required for mechanical stability was further examined. Polysorbate 80 concentration was varied from 0 to 0.02%. Mechanical stability was evaluated by agitation of MAb1 at 300 rotations per minute at room temperature for 72 h. Samples were analyzed for purity by SEC-HPLC, turbidity by absorbance at 350 nm, visible particles by visual inspection, and sub-visible particles by light obscuration technique on a particle analyzer. All non-ionic surfactants tested showed a similar effect in protecting against mechanical stress and did not exhibit any significant negative effect on thermal and photostability. However, Caprylic acid had a slightly negative effect on mechanical and photostability when compared to the non-ionic surfactants or sample without surfactant. This work demonstrated that polysorbate 80 is better than other surfactants tested and that a concentration of at least 0.005% (w/v) Polysorbate 80 is needed to protect MAb1 against mechanical stress.

Molecular dynamics simulations of phase separation in the presence of surfactants

DEFF Research Database (Denmark)

Laradji, Mohamed; Mouritsen, Ole G.; Toxvaerd, Søren

1994-01-01

The dynamics of phase separation in two-dimensional binary mixtures diluted by surfactants is studied by means of molecular dynamics simulations. In contrast to pure binary systems, characterized by an algebraic time dependence of the average domain size, we find that systems containing surfactants...... not fully phase separate, we observe a dynamical scaling which is independent of the surfactant concentration. The results of these simulations are in general in agreement with previous Langevin simulations [Laradji, Guo, Grant, and Zuckermann, J. Phys. A 44, L629 (1991)] and a theory of Ostwald ripening...... exhibit nonalgebraic, slow dynamics. The average domain size eventually saturates at a value inversely proportional to the surfactant concentration. We also find that phase separation in systems with different surfactant concentrations follow a crossover scaling form. Finally, although these systems do...

Marine toxicity and persistence of surfactants used in the petroleum producing industry

International Nuclear Information System (INIS)

Maddin, C.M.

1991-01-01

This paper presents a survey of marine toxicity and biodegradability data for surfactants used in the petroleum industry. Surfactants are key chemicals in the formulation of products such as emulsifiers, demulsifiers, dispersants and inhibitors. They are also used directly as foaming and defoaming agents. Because they function at low concentrations, below 1%, and have a tendency to adsorb on solid surfaces, their long-term environmental effects are minimal. In applications such as cementing, surfactants cannot migrate into the environment and, thus, have no bioavailability. The possibility of environmental contamination has caused well operators and regulatory agencies to require fish toxicity and persistence data for products used in servicing wells. This data has been organized for nonionic, anionic, cationic and amphoteric surfactants. Nonionic surfactants are toxic to fish at concentrations below 10 mg/L to over 2500 mg/L depending on their chemical compositions. Anionic surfactants are toxic to fish at concentrations under 1 mg/L to several hundred mg/L depending on their chemical compositions. cationic and amphoteric surfactants are generally toxic to fish at concentrations below 50 mg/L. Overall efforts are aimed at low toxicity and high biodegradability with the least compromise in product efficiency. This requires the continual testing and environmental evaluation of surfactants summarized herein

Numerical Study of Surfactant Dynamics during Emulsification in a T-Junction Microchannel.

Science.gov (United States)

Riaud, Antoine; Zhang, Hao; Wang, Xueying; Wang, Kai; Luo, Guangsheng

2018-04-18

Microchannel emulsification requires large amounts of surfactant to prevent coalescence and improve emulsions lifetime. However, most numerical studies have considered surfactant-free mixtures as models for droplet formation in microchannels, without taking into account the distribution of surfactant on the droplet surface. In this paper, we investigate the effects of nonuniform surfactant coverage on the microfluidic flow pattern using an extended lattice-Boltzmann model. This numerical study, supported by micro-particle image velocimetry experiments, reveals the likelihood of uneven distribution of surfactant during the droplet formation and the appearance of a stagnant cap. The Marangoni effect affects the droplet breakup by increasing the shear rate. According to our results, surfactant-free and surfactant-rich droplet formation processes are qualitatively different, such that both the capillary number and the Damköhler number should be considered when modeling the droplet generation in microfluidic devices. The limitations of traditional volume and pressure estimation methods for determining the dynamic interfacial tension are also discussed on the basis of the simulation results.

Comprehensive study of tartrazine/cationic surfactant interaction.

Science.gov (United States)

Shahir, Afshin Asadzadeh; Javadian, Soheila; Razavizadeh, Bi Bi Marzieh; Gharibi, Hussein

2011-12-15

Interaction of a food dye, tartrazine, with some cationic conventional and gemini surfactants, tetradecyltrimethylammonium bromide (TTAB), N,N'-ditetradecyl-N,N,N',N'-tetramethyl-N,N'-butanediyl-diammonium dibromide (14,4,14), and N,N'-didodecyl-N,N,N',N'-tetramethyl-N,N'-butanediyl-diammonium dibromide (12,4,12), were first investigated comprehensively employing conductometry, tensiometry, and UV-visible spectroscopy. Tartrazine was found to behave in the same manner as aromatic counterions. The formation of ion pairs reflected as a considerable increase of the surfactant efficiency in tensiometry plots and their stoichiometry were determined by Job's method of continuous variations. For the tartrazine/TTAB system, nonionic DS(3), ionic DS(2-), and/or DS(2)(-) ion pairs, their small premicelles, and tartrazine-rich micelles were constituted as well as dye-containing TTAB-rich micelles. Insoluble J-aggregates of DS(-) ion pairs and cylindrical surfactant-rich micelles were also formed in tartrazine/gemini surfactant systems and recognized by transmission electron microscopy. The zeta potential and the size of the aggregates were determined using dynamic light scattering and confirmed the suggested models for the processes happening in each system. Cyclic voltammetry was applied successfully to track all of these species using tartrazine's own reduction peak current for the first time.

Extraction and Characterization of Surfactants from Atmospheric Aerosols.

Science.gov (United States)

Nozière, Barbara; Gérard, Violaine; Baduel, Christine; Ferronato, Corinne

2017-04-21

Surface-active compounds, or surfactants, present in atmospheric aerosols are expected to play important roles in the formation of liquid water clouds in the Earth's atmosphere, a central process in meteorology, hydrology, and for the climate system. But because specific extraction and characterization of these compounds have been lacking for decades, very little is known on their identity, properties, mode of action and origins, thus preventing the full understanding of cloud formation and its potential links with the Earth's ecosystems. In this paper we present recently developed methods for 1) the targeted extraction of all the surfactants from atmospheric aerosol samples and for the determination of 2) their absolute concentrations in the aerosol phase and 3) their static surface tension curves in water, including their Critical Micelle Concentration (CMC). These methods have been validated with 9 references surfactants, including anionic, cationic and non-ionic ones. Examples of results are presented for surfactants found in fine aerosol particles (diameter <1 μm) collected at a coastal site in Croatia and suggestions for future improvements and other characterizations than those presented are discussed.

Use of functionalized surfactants in flame atomic analysis: Final technical report

International Nuclear Information System (INIS)

Armstrong, D.W.

1987-01-01

Research results in the following areas are briefly summarized: basic properties of surfactants, micelles, and cyclodextrins as they relate to chemical analysis; use of functionalized surfactants, micelles, and cyclodextrins in spectroscopic analysis; macromolecular separation theory and mechanism; use of functionalized surfactants and cyclodextrins in separations; capillary work for future coupling of spectroscopic and LC projects

Poloxamer-Decorated Polymer Nanoparticles for Lung Surfactant Compatibility

DEFF Research Database (Denmark)

Beck-Broichsitter, Moritz; Bohr, Adam; Ruge, Christian A

2017-01-01

Lung-delivered polymer nanoparticles provoked dysfunction of the essential lung surfactant system. A steric shielding of the nanoparticle surface with poloxamers could minimize the unwanted interference of polymer nanoparticles with the biophysical function of lung surfactant. The extent of poly......(styrene) and poly(lactide) nanoparticle-induced lung surfactant inhibition could be related to the type and content of the applied poloxamer. Escalations of the adsorbed coating layer thickness (>3 nm) as well as concentration (brush- rather than mushroom-like conformation of poly(ethylene glycol), chain......-associated proteins. Poloxamer-modified polymer nanoparticles represent a promising nanomedicine platform intended for respiratory delivery revealing negligible effects on the biophysical functionality of the lining layer present in the deep lungs....

Novel nanoparticulate carrier system based on carnauba wax and decyl oleate for the dispersion of inorganic sunscreens in aqueous media.

Science.gov (United States)

Villalobos-Hernández, J R; Müller-Goymann, C C

2005-05-01

The purpose of this study was to characterize carrier systems for inorganic sunscreens based on a matrix composed of carnauba wax and decyl oleate. Ultraviolet radiation attenuators like barium sulfate, strontium carbonate and titanium dioxide were tested. The lipid matrices were used either as capsules or as accompanying vehicles for the pigments in aqueous dispersions. Manufacturing was performed using high pressure homogenization at 300bar and a temperature of 75 degrees C. To evaluate the effect of the pigments on the crystalline structure of the wax-oil mixture, X-ray diffraction and differential scanning calorimetry were used. Further parameters determined were particle size, polydispersity index, z-potential, viscosity and sun protection factor (SPF). Transmission electron microscopy was also applied for visualization of nanoparticles. The X-ray diffraction patterns and the melting points of the lipid mixtures remained unchanged after the pigments were added. The particle sizes of the encapsulated species ranged from 239 to 749.9nm showing polydispersity values between 0.100 and 0.425. Surface charge measurements comprising values up to -40.8mV denoted the presence of stable dispersions. The formulations could be described as ideal viscous presenting viscosities in a range of 1.40-20.5mPas. Significant increases in SPF up to about 50 were reported after the encapsulation of titanium dioxide. Freeze fracture micrographs confirmed the presence of encapsulated inorganic crystals.

Surfactant therapy for maternal blood aspiration: an unusual cause of neonatal respiratory distress syndrome.

Science.gov (United States)

Celik, Istemi Han; Demirel, Gamze; Canpolat, Fuat Emre; Erdeve, Omer; Dilmen, Ugur

2012-10-01

Surfactant replacement therapy is the main treatment of neonatal respiratory distress syndrome. However, surfactant therapy has been shown to be effective in the treatment of other diseases causing neonatal respiratory diseases such as pulmonary hemorrhage, meconium aspiration syndrome, pneumonia/sepsis, pulmonary edema or acute lung injury resulting a secondary surfactant deficiency (SSD). Rarely, as like as in the present patient, exogenous blood aspiration such as breast milk or formula aspiration may lead to SSD. Blood in alveolus leads to a significant biochemical and functional disturbance of the surfactant system and inhibits surfactant production. Here, the authors report a preterm infant of 33 wk gestational age with secondary surfactant deficiency due to maternal blood aspiration because of abruptio placentae. She was received two courses of beractant, a natural bovine surfactant, therapy in 24 h. She was extubated on second day and did not require oxygen on 4(th) day. To the authors' knowledge, this is the first reported case of SSD due to maternal blood aspiration treated with surfactant. In conditions such as abruptio placentae, infant should be protected from blood aspiration and if respiratory distress occurs, surfactant inhibition and need for surfactant administration should be considered.

The Accelerated Late Adsorption of Pulmonary Surfactant

OpenAIRE

Loney, Ryan W.; Anyan, Walter R.; Biswas, Samares C.; Rananavare, Shankar B.; Hall, Stephen B.

2011-01-01

Adsorption of pulmonary surfactant to an air−water interface lowers surface tension (γ) at rates that initially decrease progressively, but which then accelerate close to the equilibrium γ. The studies here tested a series of hypotheses concerning mechanisms that might cause the late accelerated drop in γ. Experiments used captive bubbles and a Wilhelmy plate to measure γ during adsorption of vesicles containing constituents from extracted calf surfactant. The faster fall in γ reflects faster...

Binding of alkylpyridinium chloride surfactants to sodium polystyrene sulfonate

NARCIS (Netherlands)

Ishiguro, M.; Koopal, L.K.

2009-01-01

Binding of cationic surfactants to anionic polymers is well studied. However, the surfactant binding characteristics at very low concentration near the start of binding and at high concentration, where charge compensation may Occur. are less well known. Therefore, the binding characteristics of

Mineral-Surfactant Interactions for Minimum Reagents Precipitation and Adsorption for Improved Oil Recovery

Energy Technology Data Exchange (ETDEWEB)

P. Somasundaran

2008-09-20

Chemical EOR can be an effective method for increasing oil recovery and reducing the amount of produced water; however, reservoir fluids are chemically complex and may react adversely to the polymers and surfactants injected into the reservoir. While a major goal is to alter rock wettability and interfacial tension between oil and water, rock-fluid and fluid-fluid interactions must be understood and controlled to minimize reagent loss, maximize recovery and mitigate costly failures. The overall objective of this project was to elucidate the mechanisms of interactions between polymers/surfactants and the mineral surfaces responsible for determining the chemical loss due to adsorption and precipitation in EOR processes. The role of dissolved inorganic species that are dependent on the mineralogy is investigated with respect to their effects on adsorption. Adsorption, wettability and interfacial tension are studied with the aim to control chemical losses, the ultimate goal being to devise schemes to develop guidelines for surfactant and polymer selection in EOR. The adsorption behavior of mixed polymer/surfactant and surfactant/surfactant systems on typical reservoir minerals (quartz, alumina, calcite, dolomite, kaolinite, gypsum, pyrite, etc.) was correlated to their molecular structures, intermolecular interactions and the solution conditions such as pH and/or salinity. Predictive models as well as general guidelines for the use of polymer/surfactant surfactant/surfactant system in EOR have been developed The following tasks have been completed under the scope of the project: (1) Mineral characterization, in terms of SEM, BET, size, surface charge, and point zero charge. (2) Study of the interactions among typical reservoir minerals (quartz, alumina, calcite, dolomite, kaolinite, gypsum, pyrite, etc.) and surfactants and/or polymers in terms of adsorption properties that include both macroscopic (adsorption density, wettability) and microscopic (orientation

Distribution of endotracheally instilled surfactant protein SP-C in lung-lavaged rabbits.

NARCIS (Netherlands)

Bambang Oetomo, Sidarto; de Leij, Louis; Curstedt, T; ter Haar, J G; Schoots, Coenraad; Wildevuur, Charles; Okken, Albert

In lung-lavaged surfactant-deficient rabbits (n = 6) requiring artificial ventilation, porcine surfactant was instilled endotracheally. This resulted in improvement of lung function so that the animals could be weaned off artificial ventilation. The animals were killed 4 1/2 h after surfactant

The effect of titanium dioxide nanoparticles on pulmonary surfactant function and ultrastructure

Directory of Open Access Journals (Sweden)

Braun Armin

2009-09-01

Full Text Available Abstract Background Pulmonary surfactant reduces surface tension and is present at the air-liquid interface in the alveoli where inhaled nanoparticles preferentially deposit. We investigated the effect of titanium dioxide (TiO2 nanosized particles (NSP and microsized particles (MSP on biophysical surfactant function after direct particle contact and after surface area cycling in vitro. In addition, TiO2 effects on surfactant ultrastructure were visualized. Methods A natural porcine surfactant preparation was incubated with increasing concentrations (50-500 μg/ml of TiO2 NSP or MSP, respectively. Biophysical surfactant function was measured in a pulsating bubble surfactometer before and after surface area cycling. Furthermore, surfactant ultrastructure was evaluated with a transmission electron microscope. Results TiO2 NSP, but not MSP, induced a surfactant dysfunction. For TiO2 NSP, adsorption surface tension (γads increased in a dose-dependent manner from 28.2 ± 2.3 mN/m to 33.2 ± 2.3 mN/m (p min slightly increased from 4.8 ± 0.5 mN/m up to 8.4 ± 1.3 mN/m (p 2 NSP concentrations. Presence of NSP during surface area cycling caused large and significant increases in both γads (63.6 ± 0.4 mN/m and γmin (21.1 ± 0.4 mN/m. Interestingly, TiO2 NSP induced aberrations in the surfactant ultrastructure. Lamellar body like structures were deformed and decreased in size. In addition, unilamellar vesicles were formed. Particle aggregates were found between single lamellae. Conclusion TiO2 nanosized particles can alter the structure and function of pulmonary surfactant. Particle size and surface area respectively play a critical role for the biophysical surfactant response in the lung.

Inhaled Surfactant Therapy in Newborns in Artificial Lung Ventilation

Directory of Open Access Journals (Sweden)

S. A. Perepelitsa

2014-01-01

Full Text Available Objective: to evaluate the efficiency of inhaled surfactant therapy in neonatal infants with respiratory failure.Subjects and methods. The trial enrolled 13 premature neonatal infants; their mean gestational age was 31.8±2.8 weeks and the birth weight was 1825±600.9 g. They had a oneminute Apgar score of 4.3±1.4. All the neonates needed mechanical ventilation (MV atbirth because the leading clinical sign was respiratory failure caused by acute intranatal hypoxia, neonatal amniotic fluid aspiration, respiratory distress syndrome (RDS, and cerebral ischemia. Curosurf was injected in a dose of 174.7±21 mg/kg in the infants with neonatal RDS at 35 minutes of life. All the babies included in the study were noted to have severe disease and prolonged MV. After stabilization of their status, the neonates received combination therapy involving surfactantBL inhalation to reduce the duration of MV. The dose of the agent was 75 mg. Results. After surfactantBL inhalation, effective spontaneous respiration occurred in 69.2% of the newborn infants; successful extubation was carried out. The median duration ofMV after surfactant BL inhalation was 22 hours (4—68 hours. There were no reintubated cases after inhalation therapy. Following surfactantBL inhalation, 4 (30.8% patients remained to be on MV as a control regimen; 3 of them had highfre quency MV. SurfactantBL inhalation made it possible to change the respiratory support regimen and to reduce MV parame ters in these babies. 

Kinetics and mechanism for the sonochemical degradation of a nonionic surfactant.

Science.gov (United States)

Singla, Ritu; Grieser, Franz; Ashokkumar, Muthupandian

2009-03-26

The sonolytic degradation of the nonionic surfactant, octaethylene glycol monododecyl ether (C(12)E(8)), has been studied at various initial concentrations below and above its critical micelle concentration (CMC). It has been observed that the degradation rate increases with an increase in the initial concentration of the surfactant until the CMC is reached. Above the CMC an almost constant degradation rate is observed, suggesting that the surfactant in its monomer form is involved in the degradation process. The degradation process of C(12)E(8) involves two distinct primary processes occurring at the bubble/solution interface: (a) hydroxylation/oxidation of the surfactant and (b) pyrolytic fragmentation of the surfactant. The oxidative cleavage of ethylene oxide units provides evidence for OH radical attack. Hydroxylation of the ethoxy chain gives rise to various short-chain carboxyalkyl-polyethylene glycol intermediates. The polyethylene glycol chain formed, due to the scission of the C(12)E(8) molecule, undergoes rapid hydroxylation/oxidation to yield simple compounds that have the potential to undergo further degradation. The detection of multiple intermediates indicates that several processes affect the complete degradation pathways of the surfactant molecule. TOC analysis, however, indicates that the sonolytic mineralization of the surfactant is difficult to achieve at reasonable rates due to the relatively low surface activity of the degradation products formed during sonolysis.

Surfactant-Enhanced Size-Excluded Transport of Bacteria Through Unsaturated Porous Media.

Science.gov (United States)

Zhu, J.

2017-12-01

US domestic waste water is rich in surfactants because of the intensive usage of surfactants-containing household product. It results in a surfactants presence environment when this untreated waste water released into subsurface. It was reported that surfactants enhance the colloidal transport in porous media, which have significant effect on issues such as subsurface pathogens contamination and biodegradation. In this study, soil column experiments were conducted. The soil column was remained unsaturated and with a steady flow passing through it. Escherichia coli K-12 transported in the soil column and its breakthrough data was collected in presence of surfactant anionic surfactant linear alkylbenzene sulfonate (LAS) concentration range over 0, 0.25, 0.5, 0.75, 1, and 2 times Critical Micelle Concentration (CMC). It was found that the increase in LAS concentration greatly increases breakthrough concentration C/C0 and decreases breakthrough time tb until LAS concentration reaches 1 xCMC. Numerical models were built simulating and investigating this phenomenon. The goodness of model fitting was greatly improved by adding exclusion factor into the model, which indicated that the presence of surfactant might enhance the exclusion effect. The relationships between LAS concentration and the two coefficients, deposition rate coefficient k and exclusion effect coefficient θim, were found can be fitted by a quasi-Langmuir equation. And the model validation with observed data showed that the model has an acceptable reliability.

Biomimetic Fluorocarbon Surfactant Polymers Reduce Platelet Adhesion on PTFE/ePTFE Surfaces

Science.gov (United States)

Wang, Shuwu; Gupta, Anirban Sen; Sagnella, Sharon; Barendt, Pamela M.; Kottke-Marchant, Kandice; Marchant, Roger E.

2010-01-01

We describe a series of fluorocarbon surfactant polymers designed as surface-modifying agents for improving the thrombogenicity of ePTFE vascular graft materials by the reduction of platelet adhesion. The surfactant polymers consist of a poly(vinyl amine) backbone with pendent dextran and perfluoroundecanoyl branches. Surface modification is accomplished by a simple dip-coating process in which surfactant polymers undergo spontaneous surface-induced adsorption and assembly on PTFE/ePTFE surface. The adhesion stability of the surfactant polymer on PTFE was examined under dynamic shear conditions in PBS and human whole blood with a rotating disk system. Fluorocarbon surfactant polymer coatings with three different dextran to perfluorocarbon ratios (1:0.5, 1:1 and 1:2) were compared in the context of platelet adhesion on PTFE/ePTFE surface under dynamic flow conditions. Suppression of platelet adhesion was achieved for all three coated surfaces over the shear-stress range of 0–75 dyn/cm2 in platelet-rich plasma (PRP) or human whole blood. The effectiveness depended on the surfactant polymer composition such that platelet adhesion on coated surfaces decreased significantly with increasing fluorocarbon branch density at 0 dyn/cm2. Our results suggest that fluorocarbon surfactant polymers can effectively suppress platelet adhesion and demonstrate the potential application of the fluorocarbon surfactant polymers as non-thrombogenic coatings for ePTFE vascular grafts. PMID:19323880

Alpha-1-antitrypsin studies: canine serum and canine surfactant protein

International Nuclear Information System (INIS)

Tuttle, W.C.; Slauson, D.O.; Dahlstrom, M.; Gorman, C.

1974-01-01

Canine serum alpha-1-antitrypsin was isolated by gel filtration and affinity chromatography and characterized by polyacrylamide gel electrophoresis and immunoelectrophoresis. Measurement of the trypsin inhibitory capacity of the separated protein indicated a ninefold concentration of functional trypsin inhibitor during the isolation procedure. Electrophoresis demonstrated the presence of a single protein with alpha-globulin mobility and a molecular weight near that of human alpha-1-antitrypsin. The trypsin inhibitory capacity of pulmonary surfactant protein from five Beagle dogs was measured, related to total surfactant protein concentration, and compared with similar measurements on whole serum from the same animals. Results indicated a variable concentration of trypsin inhibitor in the canine pulmonary surfactant protein. However, the concentration in the surfactant protein was always significantly higher than that in the corresponding serum sample. Preliminary experiments designed to separate the trypsin inhibitory fraction(s) from the other surfactant proteins by gel filtration chromatography indicated that the trypsin inhibitor was probably a single protein with a molecular weight near that of alpha-1-antitrypsin. (U.S.)

A review of shampoo surfactant technology: consumer benefits, raw materials and recent developments.

Science.gov (United States)

Cornwell, P A

2018-02-01

Surfactants form the core of all shampoo formulations, and contribute to a wide range of different benefits, including cleansing, foaming, rheology control, skin mildness and the deposition of benefit agents to the hair and scalp. The purpose of this review was to assist the design of effective, modern, shampoo surfactant technologies. The mechanisms through which surfactants help deliver their effects are presented, along with the appraisal techniques through which surfactant options can be tested and screened for product development. The steps that should be taken to select the most appropriate blend of surfactants are described, and useful information on the most widely used surfactants is provided. The review concludes with an examination of recent developments in 'greener' surfactants, 'sulphate-free' technologies and structured liquid phases for novel sensory properties and for suspending benefit agents. © 2017 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Surfactant Effect on the Average Flow Generation Near Curved Interface

Science.gov (United States)

Klimenko, Lyudmila; Lyubimov, Dmitry

2018-02-01

The present work is devoted to the average flow generation near curved interface with a surfactant adsorbed on the surface layer. The investigation was carried out for a liquid drop embedded in a viscous liquid with a different density. The liquid flows inside and outside the drop are generated by small amplitude and high frequency vibrations. Surfactant exchange between the drop surface and the surrounding liquid is limited by the process of adsorption-desorption. It was assumed that the surfactant is soluble in the surrounding liquid, but not soluble in the liquid drop. Surrounding liquid and the liquid in the drop are considered incompressible. Normal and shear viscous stresses balance at the interface is performed under the condition that the film thickness of the adsorbed surfactant is negligible. The problem is solved under assumption that the shape of the drop in the presence of adsorbed surfactant remains spherical symmetry. The effective boundary conditions for the tangential velocity jump and shear stress jump, describing the above generation have been obtained by matched asymptotic expansions method. The conditions under which the drop surface can be considered as a quasi-solid are determined. It is shown that in the case of the significant effect of surfactant on the surface tension, the dominant mechanism for the generation is the Schlichting mechanisms under vibrations.

Induction of virulence gene expression in Staphylococcus aureus by pulmonary surfactant.

Science.gov (United States)

Ishii, Kenichi; Adachi, Tatsuo; Yasukawa, Jyunichiro; Suzuki, Yutaka; Hamamoto, Hiroshi; Sekimizu, Kazuhisa

2014-04-01

We performed a genomewide analysis using a next-generation sequencer to investigate the effect of pulmonary surfactant on gene expression in Staphylococcus aureus, a clinically important opportunistic pathogen. RNA sequence (RNA-seq) analysis of bacterial transcripts at late log phase revealed 142 genes that were upregulated >2-fold following the addition of pulmonary surfactant to the culture medium. Among these genes, we confirmed by quantitative reverse transcription-PCR analysis that mRNA amounts for genes encoding ESAT-6 secretion system C (EssC), an unknown hypothetical protein (NWMN_0246; also called pulmonary surfactant-inducible factor A [PsiA] in this study), and hemolysin gamma subunit B (HlgB) were increased 3- to 10-fold by the surfactant treatment. Among the major constituents of pulmonary surfactant, i.e., phospholipids and palmitate, only palmitate, which is the most abundant fatty acid in the pulmonary surfactant and a known antibacterial substance, stimulated the expression of these three genes. Moreover, these genes were also induced by supplementing the culture with detergents. The induction of gene expression by surfactant or palmitate was not observed in a disruption mutant of the sigB gene, which encodes an alternative sigma factor involved in bacterial stress responses. Furthermore, each disruption mutant of the essC, psiA, and hlgB genes showed attenuation of both survival in the lung and host-killing ability in a murine pneumonia model. These findings suggest that S. aureus resists membrane stress caused by free fatty acids present in the pulmonary surfactant through the regulation of virulence gene expression, which contributes to its pathogenesis within the lungs of the host animal.

Membrane-surfactant interactions. The role of surfactant in mitochondrial complex III-phospholipid-Triton X-100 mixed micelles

International Nuclear Information System (INIS)

Valpuesta, J.M.; Arrondo, J.L.; Barbero, M.C.; Pons, M.; Goni, F.M.

1986-01-01

Complex III (ubiquinol-cytochrome c reductase) was purified from beef heart mitochondria in the form of protein-phospholipid-Triton X-100 mixed micelles (about 1:80:100 molar ratio). Detergent may be totally removed by sucrose density gradient centrifugation, and the resulting lipoprotein complexes retain full enzyme activity. In order to understand the role of surfactant in the mixed micelles, and the interaction of Triton X-100 with integral membrane proteins and phospholipid bilayers, both the protein-lipid-surfactant mixed micelles and the detergent-free lipoprotein system were examined from the point of view of particle size and ultrastructure, enzyme activity, tryptophan fluorescence quenching, 31P NMR, and Fourier transform infrared spectroscopy. The NMR and IR spectroscopic studies show that surfactant withdrawal induces a profound change in phospholipid architecture, from a micellar to a lamellar-like phase. However, electron microscopic observations fail to reveal the existence of lipid bilayers in the absence of detergent. We suggest that, under these conditions, the lipid:protein molar ratio (80:1) is too low to permit the formation of lipid bilayer planes, but the relative orientation and mobility of phospholipids with respect to proteins is similar to that of the lamellar phase. Protein conformational changes are also detected as a consequence of surfactant removal. Fourier transform infrared spectroscopy indicates an increase of peptide beta-structure in the absence of Triton X-100; changes in the amide II/amide I intensity ratio are also detected, although the precise meaning of these observations is unclear

Optimization of surfactant-aided remediation of industrially contaminated soils

International Nuclear Information System (INIS)

Joshi, M.M.; Lee, S.

1996-01-01

Soil matrices contaminated with polycyclic aromatic hydrocarbons (PAHs) abound at the sites of coke-oven gas plants, refineries, and many other major chemical industries. The removal of PAHs from soil using pure water, via soil washing (ex situ) or soil flushing (in situ), is quite ineffective due to their low solubility and hydrophobicity. However, addition of suitable surfactant(s) has been shown to increase the removal efficiency several fold. For the present work, the removal of PAHs occurring in industrially contaminated soil was studied. The objective was to use a nonionic surfactant solution for in situ soil flushing and to evaluate the optimal range of process parameters that can significantly increase the removal efficiency. The process parameters chosen were surfactant concentration, ratio of washing solution volume to soil weight, and temperature of washing solution. These parameters were found to have a significant effect on PAH removal from the contaminated soil and an optimal range was determined for each parameter under given washing conditions

Mechanisms of dynamic wetting failure in the presence of soluble surfactants

Science.gov (United States)

Kumar, Satish; Liu, Chen-Yu; Carvalho, Marcio S.

2017-11-01

A hydrodynamic model and flow visualization experiments are used to understand the mechanisms through which soluble surfactants can influence the onset of dynamic wetting failure. In the model, a Newtonian liquid displaces air in a rectangular channel in the absence of inertia. A Navier-slip boundary condition and constant contact angle are used to describe the dynamic contact line, and surfactants are allowed to adsorb to the interface and moving channel wall (substrate). The Galerkin finite element method is used to calculate steady states and identify the critical capillary number Cacrit at which wetting failure occurs. It is found that surfactant solubility weakens the influence of Marangoni stresses, which tend to promote the onset of wetting failure. The experiments indicate that Cacrit increases with surfactant concentration. For the more viscous solutions used, this behaviour can largely be explained by accounting for changes to the mean surface tension and static contact angle produced by surfactants. For the lowest-viscosity solution used, comparison between the model predictions and experimental observations suggests that other surfactant-induced phenomena such as Marangoni stresses may play a more important role.

Synthesis, surface properties and antimicrobial activity of some germanium nonionic surfactants.

Science.gov (United States)

Zaki, Mohamed F; Tawfik, Salah M

2014-01-01

Esterification reaction between different fatty acid namely; lauric, stearic, oleic and linoleic acids and polyethylene glycol-400 were performed. The produced polyethylene glycol ester were reacted with p-amine benzoic acid followed by condensation reaction with germanium dioxide in presence of sodium carbonate to form desired germinate surfactants. The chemical structures of the synthesized surfactants were determined using different spectra tools. The surface parameter including: the critical micelle concentration (CMC), effectiveness (π(cmc)), efficiency (Pc20), maximum surface excess (Γ(max)) and minimum surface area (A(min)), were calculated from the surface tension measurements. The synthesized surfactants showed higher surface activity. The thermodynamic parameters showed that adsorption and micellization processes are spontaneous. It is clear that the synthesized nonionic surfactants showed their tendency towards adsorption at the interfaces and also micellization in the bulk of their solutions. The synthesized surfactants were tested against different strain of bacteria using inhibition zone diameters. The synthesized surfactants showed good antimicrobial activities against the tested microorganisms including Gram positive, Gram negative as well as fungi. The promising inhibition efficiency of these compounds against the sulfate reducing bacteria facilitates them to be applicable as new categories of sulfate reducing bacteria biocides.

Mechanisms of polyelectrolyte enhanced surfactant adsorption at the air-water interface.

Science.gov (United States)

Stenger, Patrick C; Palazoglu, Omer A; Zasadzinski, Joseph A

2009-05-01

Chitosan, a naturally occurring cationic polyelectrolyte, restores the adsorption of the clinical lung surfactant Survanta to the air-water interface in the presence of albumin at much lower concentrations than uncharged polymers such as polyethylene glycol. This is consistent with the positively charged chitosan forming ion pairs with negative charges on the albumin and lung surfactant particles, reducing the net charge in the double-layer, and decreasing the electrostatic energy barrier to adsorption to the air-water interface. However, chitosan, like other polyelectrolytes, cannot perfectly match the charge distribution on the surfactant, which leads to patches of positive and negative charge at net neutrality. Increasing the chitosan concentration further leads to a reduction in the rate of surfactant adsorption consistent with an over-compensation of the negative charge on the surfactant and albumin surfaces, which creates a new repulsive electrostatic potential between the now cationic surfaces. This charge neutralization followed by charge inversion explains the window of polyelectrolyte concentration that enhances surfactant adsorption; the same physical mechanism is observed in flocculation and re-stabilization of anionic colloids by chitosan and in alternate layer deposition of anionic and cationic polyelectrolytes on charged colloids.

SCREENING METHODS FOR SELECTION OF SURFACTANT FORMULATIONS FOR IOR FROM FRACTURED CARBONATE RESERVOIRS

Energy Technology Data Exchange (ETDEWEB)

William A. Goddard III; Yongchun Tang; Patrick Shuler; Mario Blanco; Yongfu Wu; Seung Soon Jang

2005-07-01

This topical report presents details of the laboratory work performed to complete Task 1 of this project; developing rapid screening methods to assess surfactant performance for IOR (Improved Oil Recovery) from fractured carbonate reservoirs. The desired outcome is to identify surfactant formulations that increase the rate and amount of aqueous phase imbibition into oil-rich, oil-wet carbonate reservoir rock. Changing the wettability from oil-wet to water-wet is one key to enhancing this water-phase imbibition process that in turn recovers additional oil from the matrix portion of a carbonate reservoir. The common laboratory test to evaluate candidate surfactant formulations is to measure directly the aqueous imbibition rate and oil recovery from small outcrop or reservoir cores, but this procedure typically requires several weeks. Two methods are presented here for the rapid screening of candidate surfactant formulations for their potential IOR performance in carbonate reservoirs. One promising surfactant screening protocol is based on the ability of a surfactant solution to remove aged crude oil that coats a clear calcite crystal (Iceland Spar). Good surfactant candidate solutions remove the most oil the quickest from the chips, plus change the apparent contact angle of the remaining oil droplets on the surface that thereby indicate increased water-wetting. The other fast surfactant screening method is based on the flotation behavior of powdered calcite in water. In this test protocol, first the calcite power is pre-treated to make the surface oil-wet. The next step is to add the pre-treated powder to a test tube and add a candidate aqueous surfactant formulation; the greater the percentage of the calcite that now sinks to the bottom rather than floats, the more effective the surfactant is in changing the solids to become now preferentially water-wet. Results from the screening test generally are consistent with surfactant performance reported in the literature.

Magnetic surfactants as molecular based-magnets with spin glass-like properties

International Nuclear Information System (INIS)

Brown, Paul; Hatton, T Alan; Smith, Gregory N; Hernández, Eduardo Padrón; James, Craig; Eastoe, Julian; Nunes, Wallace C; Settens, Charles M; Baker, Peter J

2016-01-01

This paper reports the use of muon spin relaxation spectroscopy to study how the aggregation behavior of magnetic surfactants containing lanthanide counterions may be exploited to create spin glass-like materials. Surfactants provide a unique approach to building in randomness, frustration and competing interactions into magnetic materials without requiring a lattice of ordered magnetic species or intervening ligands and elements. We demonstrate that this magnetic behavior may also be manipulated via formation of micelles rather than simple dilution, as well as via design of surfactant molecular architecture. This somewhat unexpected result indicates the potential of using novel magnetic surfactants for the generation and tuning of molecular magnets. (paper)

Surfactants: behavior and some of their applications in the petroleum industry

International Nuclear Information System (INIS)

Rivas, Hercilio; Gutierrez, Xiomara

1999-01-01

The most important theoretical aspect related to the behavior of surfactants in solution and the mechanism which govern the processes of their adsorption at the liquid - liquid, liquid- gas and liquid - solid interfaces are discussed in this paper. The basic principles, which characterize the phase behavior of surfactants in solution are described, and the procedures for stablishing the condition under which surfactants ca be successfully used in basic and applied research activities are given. Finally, the most important aspect of the different processes carried out in the oil industry, with special mention to those in exploration and production, where the surfactants play a very important role, are briefly discussed

Surfactant media for constant-current coulometry. Application for the determination of antioxidants in pharmaceuticals

Energy Technology Data Exchange (ETDEWEB)

Ziyatdinova, Guzel, E-mail: Ziyatdinovag@mail.ru [Analytical Chemistry Department, A.M. Butlerov Institute of Chemistry, Kazan (Volga Region) Federal University, Kremlyevskaya, 18, Kazan 420008 (Russian Federation); Ziganshina, Endzhe; Budnikov, Herman [Analytical Chemistry Department, A.M. Butlerov Institute of Chemistry, Kazan (Volga Region) Federal University, Kremlyevskaya, 18, Kazan 420008 (Russian Federation)

2012-09-26

Highlights: Black-Right-Pointing-Pointer Applicability of surfactants in constant-current coulometry is shown for the first time. Black-Right-Pointing-Pointer Reactions of antioxidants with electrogenerated titrants in surfactant media are investigated. Black-Right-Pointing-Pointer Water insoluble antioxidants can be determined in water media with addition of surfactants. Black-Right-Pointing-Pointer Coulometric determination of antioxidants in pharmaceutical dosage forms using surfactants media is developed. - Abstract: Effect of surfactant presence on electrochemical generation of titrants has been evaluated and discussed for the first time. Cationic (1-dodecylpyridinium and cetylpyridinium bromide), anionic (sodium dodecyl sulfate) and nonionic (Triton X100 and Brij{sup Registered-Sign} 35) surfactants as well as nonionic high molecular weight polymer (PEG 4000) do not react with the electrogenerated bromine, iodine and hexacyanoferrate(III) ions. The electrogenerated chlorine chemically interact with Triton X100 and Brij{sup Registered-Sign} 35. The allowable range of surfactants concentrations providing 100% current yield has been found. Chain-breaking low molecular weight antioxidants (ascorbic acid, rutin, {alpha}-tocopherol and retinol) were determined by reaction with the electrogenerated titrants in surfactant media. Nonionic and cationic surfactants can be used for the determination of antioxidants by reaction with the electrogenerated halogens. On contrary, cationic surfactants gives significantly overstated results of antioxidants determination with electrogenerated hexacyanoferrate(III) ions. The use of surfactants in coulometry of {alpha}-tocopherol and retinol provides their solubilization and allows to perform titration in water media. Simple, express and reliable coulometric approach for determination of {alpha}-tocopherol, rutin and ascorbic acid in pharmaceuticals using surfactant media has been developed. The relative standard deviation of the

Cost Effective Surfactant Formulations for Improved Oil Recovery in Carbonate Reservoirs

Energy Technology Data Exchange (ETDEWEB)

William A. Goddard; Yongchun Tang; Patrick Shuler; Mario Blanco; Yongfu Wu

2007-09-30

This report summarizes work during the 30 month time period of this project. This was planned originally for 3-years duration, but due to its financial limitations, DOE halted funding after 2 years. The California Institute of Technology continued working on this project for an additional 6 months based on a no-cost extension granted by DOE. The objective of this project is to improve the performance of aqueous phase formulations that are designed to increase oil recovery from fractured, oil-wet carbonate reservoir rock. This process works by increasing the rate and extent of aqueous phase imbibition into the matrix blocks in the reservoir and thereby displacing crude oil normally not recovered in a conventional waterflood operation. The project had three major components: (1) developing methods for the rapid screening of surfactant formulations towards identifying candidates suitable for more detailed evaluation, (2) more fundamental studies to relate the chemical structure of acid components of an oil and surfactants in aqueous solution as relates to their tendency to wet a carbonate surface by oil or water, and (3) a more applied study where aqueous solutions of different commercial surfactants are examined for their ability to recover a West Texas crude oil from a limestone core via an imbibition process. The first item, regarding rapid screening methods for suitable surfactants has been summarized as a Topical Report. One promising surfactant screening protocol is based on the ability of a surfactant solution to remove aged crude oil that coats a clear calcite crystal (Iceland Spar). Good surfactant candidate solutions remove the most oil the quickest from the surface of these chips, plus change the apparent contact angle of the remaining oil droplets on the surface that thereby indicate increased water-wetting. The other fast surfactant screening method is based on the flotation behavior of powdered calcite in water. In this test protocol, first the calcite

Inactivation of pulmonary surfactant due to serum-inhibited adsorption and reversal by hydrophilic polymers: experimental

DEFF Research Database (Denmark)

Taeusch, H William; de la Serna, Jorge Bernardino; Perez-Gil, Jesus

2005-01-01

adsorption of surface active serum proteins. Aqueous suspensions of native porcine surfactant, organic extracts of native surfactant, and the clinical surfactants Curosurf, Infasurf, and Survanta spread on buffered subphases increase the surface pressure, pi, to approximately 40 mN/m within 2 min....... The variation with concentration, temperature, and mode of spreading confirmed Brewster angle microscopy observations that subphase to surface adsorption of surfactant is the dominant form of surfactant transport to the interface. However (with the exception of native porcine surfactant), similar rapid...... increases in pi did not occur when surfactants were applied to subphases containing serum. Components of serum are surface active and adsorb reversibly to the interface increasing pi up to a concentration-dependent saturation value, pi(max). When surfactants were applied to subphases containing serum...

Application of surfactant enhanced permanganate oxidation and bidegradation of trichloroethylene in groundwater

Energy Technology Data Exchange (ETDEWEB)

Tsai, T.T.; Kao, C.M. [Institute of Environmental Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan (China); Yeh, T.Y. [Department of Civil and Environmental Engineering, National University of Kaohsiung, Kaohsiung, Taiwan (China)], E-mail: tyyeh@nuk.edu.tw; Liang, S.H.; Chien, H.Y. [Institute of Environmental Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan (China)

2009-01-15

The industrial solvent trichloroethylene (TCE) is among the most ubiquitous chlorinated solvents found in groundwater contamination. The main objectives of this study were to evaluate the feasibility of using non-ionic surfactant Simple Green{sup TM} (SG) to enhance the oxidative dechlorination of TCE by potassium permanganate (KMnO{sub 4}) employing a continuous stir batch reactor system (CSBR) and column experiments. The effect of using surfactant SG to enhance the biodegradation of TCE via aerobic cometabolism was also examined. Results from CSBR experiments revealed that combination of KMnO{sub 4} with surfactant SG significantly enhanced contaminant removal, particularly when the surfactant SG concentrated at its CMC. TCE degradation rates ranged from 74.1% to 85.7% without addition of surfactant SG while TCE degradation rates increased to ranging from 83.8% to 96.3% with presence of 0.1 wt% SG. Furthermore, results from column experiments showed that TCE was degraded from 38.1 {mu}M to 6.2 {mu}M in equivalent to 83.7% of TCE oxidation during first 560 min reaction. This study has also demonstrated that the addition of surfactant SG is a feasible method to enhance bioremediation efficiency for TCE contaminated groundwater. The complete TCE degradation was detected after 75 days of incubation with both 0.01 and 0.1 wt% of surfactant SG addition. Results revealed that surfactant enhanced chemical oxidation and bioremediation technology is one of feasible approaches to clean up TCE contaminated groundwater.

The magnetic properties of aligned M hexa-ferrite fibres

International Nuclear Information System (INIS)

Pullar, R.C.; Bhattacharya, A.K.

2006-01-01

Aligned and random fibres of strontium hexa ferrite (SrM, SrFe 12 O 19 ) and barium hexaferrite (BaM, BaFe 12 O 19 ) were manufactured by blow spinning from an aqueous inorganic sol-gel precursor, which was then fired to give the hexagonal ferrite fibre. Their magnetic properties were studied by VSM, investigating the evolution of these properties with firing and measurement temperature, and in particular the effects of fibre alignment. It has been predicted that aligned ferrite fibres will demonstrate an enhanced magnetisation along the axis of alignment with respect to perpendicular to the axis, and this has been demonstrated here for the first time. The optimum firing temperature was 1000 deg. C, at which point they still had submicron grains. In BaM random fibres M s =63.8 emu g -1 and H c =428.1 kA m -1 , and in SrM random fibres M s =63.3 emu g -1 and H c =452.8 kA m -1 , high values for polycrystalline materials. Fibres aligned parallel to the applied field had saturation magnetisation (M s ) values equal to those of the random fibres, whilst fibres aligned perpendicular to the field had M s values 62% and 75% lower, for BaM and SrM, respectively. There was no change in coercivity (H c ) between random or aligned fibres of any orientation, and fibres aligned 45 deg. and parallel to H appeared identical. Therefore, properties along the axis of alignment were superior when compared to measurements perpendicular to the axis of alignment, giving a directionality to the magnetisation in an otherwise randomly oriented ferrite material

Flavonoid-surfactant interactions: A detailed physicochemical study

Science.gov (United States)

Singh, Onkar; Kaur, Rajwinder; Mahajan, Rakesh Kumar

2017-01-01

The aim of this article is to study the interactions between flavonoids and surfactants with attention of finding the probable location of flavonoids in micellar media that can be used for controlling their antioxidant behavior. In present study, the micellar and interfacial behavior of twin tailed anionic surfactants viz. sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and sodium bis(2-ethylhexyl)phosphate (NaDEHP) in the presence of two flavonoids, namely quercetin (QUE) and kaempferol (KFL) have been studied by surface tension measurements. UV-visible, fluorescence and differential pulse voltammetric (DPV) measurements have been employed to predict the probable location of flavonoids (QUE/KFL) within surfactant (AOT/NaDEHP) aggregates. Dynamic light scattering (DLS) measurements further confirmed the solubilization of QUE/KFL in AOT/NaDEHP aggregates deduced from increased hydrodynamic diameter (Dh) of aggregates in the presence of flavonoids. Both radical scavenging activity (RSA) and degradation rate constant (k) of flavonoids are found to be higher in NaDEHP micelles as compared to AOT micelles.

Systematic Investigation of the Role of Surfactant Composition and Choice of oil

DEFF Research Database (Denmark)

Schmidt, Signe Tandrup; Neustrup, Malene Aaby; Harloff-Helleberg, Stine

2017-01-01

humoral and CMI responses. METHODS: The influence of emulsion composition was analyzed using a systematic approach. Three factors were varied: i) saturation of the oil phase, ii) type and saturation of the applied surfactant mixture, and iii) surfactant mixture net charge. RESULTS: The emulsions were...... colloidally stable with a droplet diameter of 150-250 nm, and the zeta-potential correlated closely with the net charge of the surfactant mixture. Only cationic emulsions containing the unsaturated surfactant mixture induced concomitant humoral and CMI responses upon immunization of mice with a Ct antigen...

Interaction of biocompatible natural rosin-based surfactants with human serum albumin: A biophysical study

International Nuclear Information System (INIS)

Ishtikhar, Mohd; Ali, Mohd Sajid; Atta, Ayman M.; Al-Lohedan, H.A.; Nigam, Lokesh; Subbarao, Naidu; Hasan Khan, Rizwan

2015-01-01

Biophysical insight into interaction of biocompatible rosin-based surfactants with human serum albumin (HSA) was studied at physiological conditions using various spectroscopic, calorimetric and molecular docking approaches. The binding constant (K b ), enthalpy (ΔH 0 ), entropy (ΔS 0 ) and Gibbs free energy change (ΔG 0 ) were calculated by spectroscopic and calorimetric method. We have also calculated the probability of energy transfer by FRET analysis. The circular dichroism study showed that the cationic surfactant QRMAE significantly altered the secondary structure of HSA as compared to the nonionic rosin surfactants. The thermodynamic study was performed by ITC to determine binding constant as well as change in enthalpy of HSA in presence of rosin surfactants. It clearly showed that hydrogen binding and hydrophobic interaction play an important role in the binding of HSA to rosin surfactants. We have also performed molecular docking studies to locate the binding site on HSA and to visualize the mode of interaction. The present study provides a significant insight into HSA–rosin surfactants interaction, which also improves our understanding of the possible effect of rosin surfactants on human health. - Highlights: • RMPEG 750 has the highest Kb, Kq and Ksv value as compared to other rosin surfactants. • The probability of energy transfer from HSA to rosin surfactants was maximum in the case of RMPEG 750. • Cationic surfactant QRMAE significantly altered the secondary structure of the HSA as compared to other rosin surfactants. • Molecular docking and ITC experiment studies, to locate the binding site on HSA and to investigate the mode of interaction

Surfactant-thermal method to prepare two new cobalt metal-organic frameworks

Energy Technology Data Exchange (ETDEWEB)

Yu, Xianglin [School of Materials Science and Engineering and School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430074 (China); Toh, Yong Siang [School of Materials Science and Engineering and School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Zhao, Jun [College of Materials and Chemical Engineering, Hubei Provincial Collaborative Innovation Center for New Energy Microgrid, China Three Gorges University, Yichang 443002 (China); Nie, Lina [School of Materials Science and Engineering and School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Ye, Kaiqi; Wang, Yue [State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012 (China); Li, Dongsheng [College of Materials and Chemical Engineering, Hubei Provincial Collaborative Innovation Center for New Energy Microgrid, China Three Gorges University, Yichang 443002 (China); Zhang, Qichun, E-mail: qczhang@ntu.edu.sg [School of Materials Science and Engineering and School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore)

2015-12-15

Employing surfactants as reaction media, two new metal-organic frameworks (MOFs):(HTEA){sub 3}[Co{sub 3}(BTC){sub 3}] (NTU-Z33) and (HTEA)[Co{sub 3}(HBTC){sub 2}(BTC)] (NTU-Z34) (H{sub 3}BTC=1,3,5-benzenetricarboxylic acid, TEA=trimethylamine, and NTU=Nanyang Technological University), have been successfully synthesized and fully characterized. Note that NTU-Z33 has an unusual trimeric [Co{sub 3}(COO){sub 9}] secondary building unit (SBU). Magnetic characterization suggests that both compounds have weak antiferromagnetic behaviors. Our success in preparing new crystalline Co-BTC based MOFs under different surfactant media could provide a new road to prepare new diverse MOFs through various combinations of surfactants. - Graphical abstract: Employing surfactants as reaction media, two new metal-organic frame-works (MOFs) have been successfully synthesized and magnetic study suggests that both compounds have weak antiferromagnetic behaviors. - Highlights: • Two novel metal-organic frame-works (MOFs). • Synthesis through surfactant-thermal condition. • weak antiferromagnetic behaviors for both compounds.

Surfactant-thermal method to prepare two new cobalt metal-organic frameworks

International Nuclear Information System (INIS)

Yu, Xianglin; Toh, Yong Siang; Zhao, Jun; Nie, Lina; Ye, Kaiqi; Wang, Yue; Li, Dongsheng; Zhang, Qichun

2015-01-01

Employing surfactants as reaction media, two new metal-organic frameworks (MOFs):(HTEA)_3[Co_3(BTC)_3] (NTU-Z33) and (HTEA)[Co_3(HBTC)_2(BTC)] (NTU-Z34) (H_3BTC=1,3,5-benzenetricarboxylic acid, TEA=trimethylamine, and NTU=Nanyang Technological University), have been successfully synthesized and fully characterized. Note that NTU-Z33 has an unusual trimeric [Co_3(COO)_9] secondary building unit (SBU). Magnetic characterization suggests that both compounds have weak antiferromagnetic behaviors. Our success in preparing new crystalline Co-BTC based MOFs under different surfactant media could provide a new road to prepare new diverse MOFs through various combinations of surfactants. - Graphical abstract: Employing surfactants as reaction media, two new metal-organic frame-works (MOFs) have been successfully synthesized and magnetic study suggests that both compounds have weak antiferromagnetic behaviors. - Highlights: • Two novel metal-organic frame-works (MOFs). • Synthesis through surfactant-thermal condition. • weak antiferromagnetic behaviors for both compounds.

Study on the surfactants present in atmospheric aerosols collected in the Okinawa Japan

Science.gov (United States)

Kamegawa, A.; Kasaba, T.; Shimabukuro, W.; Arakaki, T.

2017-12-01

The main constituent of atmospheric aerosols is organic substances, which occupy 20 to 70% of the mass. Organic matters in the aerosols contain organic acids, protein and humic acid, which behave similar to surfactants. Since surfactants contain both hydrophobic and hydrophilic functional groups in the molecule, they can play important roles in cloud formation and can affect climate change, but detailed mechanisms and magnitude are not well understood. In addition, surfactants can cause asthma, allergy, dry eye and so on. In this study, our aim is to characterize surfactants in the aerosols collected in different seasons in Okinawa, Japan. Atmospheric aerosols were collected at Cape Hedo Atmosphere and Aerosol Monitoring Station (CHAAMS) during Sep. 2013 and July 2014. Surfactants in the environment are comprised of artificially synthesized compounds and naturally derived organics so we only differentiate them into anionic and cationic surfactants. Colorimetric methods were used to determine the concentrations of anionic surfactants as methylene blue active substance (MBAS). Cationic surfactants were also measured by colorimetric method as disulfine blue active substance (DBAS) and showed always below detection limit. Thus, we only discuss anionic surfactants measured as MBAS. Water soluble organic carbon (WSOC) and metal concentrations were also measured for the same aerosol samples. Concentrations of MBAS in the studied samples were 2-3 times higher in spring, fall and winter than those collected in summer. MBAS concentration in the aerosols showed strong correlation with sulfate ion and WSOC, and slightly weaker correlation with nss-sulfate ion. Among the metals, only sodium ion showed a relatively strong correlation with MBAS concentrations. It is suggested that the anionic surfactants in the studied aerosols are mainly derived from marine sources.

Control of stain geometry by drop evaporation of surfactant containing dispersions.

Science.gov (United States)

Erbil, H Yildirim

2015-08-01

Control of stain geometry by drop evaporation of surfactant containing dispersions is an important topic of interest because it plays a crucial role in many applications such as forming templates on solid surfaces, in ink-jet printing, spraying of pesticides, micro/nano material fabrication, thin film coatings, biochemical assays, deposition of DNA/RNA micro-arrays, and manufacture of novel optical and electronic materials. This paper presents a review of the published articles on the diffusive drop evaporation of pure liquids (water), the surfactant stains obtained from evaporating drops that do not contain dispersed particles and deposits obtained from drops containing polymer colloids and carbon based particles such as carbon nanotubes, graphite and fullerenes. Experimental results of specific systems and modeling attempts are discussed. This review also has some special subtopics such as suppression of coffee-rings by surfactant addition and "stick-slip" behavior of evaporating nanosuspension drops. In general, the drop evaporation process of a surfactant/particle/substrate system is very complex since dissolved surfactants adsorb on both the insoluble organic/inorganic micro/nanoparticles in the drop, on the air/solution interface and on the substrate surface in different extends. Meanwhile, surfactant adsorbed particles interact with the substrate giving a specific contact angle, and free surfactants create a solutal Marangoni flow in the drop which controls the location of the particle deposition together with the rate of evaporation. In some cases, the presence of a surfactant monolayer at the air/solution interface alters the rate of evaporation. At present, the magnitude of each effect cannot be predicted adequately in advance and consequently they should be carefully studied for any system in order to control the shape and size of the final deposit. Copyright © 2014 Elsevier B.V. All rights reserved.

New thermo-sensitive chelating surfactants for selective solvent-free extraction of uranyl nitrate

International Nuclear Information System (INIS)

Prevost, S.; Larpent, C.; Testard, F.; Coulombeau, H.; Baczko, K.; Berthon, L.; Desvaux, H.; Madic, C.; Zemb, T.

2004-01-01

Functional surfactants were synthesised by grafting a chelating group (amino-acid residue) to the tip of a poly-ethoxylated nonionic surfactant chain (C i E j : C i H 2i +1(OCH 2 CH 2 ) j OH)) or in a branched position. C i E j nonionic surfactants are known to be thermo-reversible and to exhibit a clouding phenomenon associated to phase separation of micelles. The functional surfactants retain both surface-active properties, characteristic thermo-reversible behaviour and have efficient complexing properties toward uranyl. In the presence of uranyl nitrate, small micelles are formed at ambient temperature and the de-mixing leads to a separation of the target ion trapped by the functional surfactant (cloud point extraction). Those surfactants are more efficient than mixture of classical C i E j and complexing agent solubilized in the micelles. This reveals a synergistic effect of the covalent bond between the chelating group and the nonionic surfactant C i E j . This paper presents a systematic study of the extraction and aggregation properties and the influence of the nature of the ions. (authors)

The influence of nonionic surfactant Brij 30 on biodegradation of ...

African Journals Online (AJOL)

ONOS

2010-09-06

Sep 6, 2010 ... polluted air stream using biological process is highly efficient and has low ... Brij 30 was the most biodegradable surfactant among Brij 30, Tween 80 and ... The filter material contained surfactants that would enhance the ...

Surfactant from neonatal to pediatric ICU: bench and bedside evidence.

Science.gov (United States)

Boet, A; Brat, R; Aguilera, S S; Tissieres, P; De Luca, D

2014-12-01

Surfactant is a cornerstone of neonatal critical care for the treatment of respiratory distress syndrome of preterm babies. However, other indications have been studied for various clinical conditions both in term neonates and in children beyond neonatal age. A high degree of evidence is not yet available in some cases and this is due to the complex and not yet totally understood physiopathology of the different types of pediatric and neonatal lung injury. We here summarise the state of the art of the bench and bedside knowledge about surfactant use for the respiratory conditions usually cared for in neonatal and pediatric intensive care units. Future research direction will also be presented. On the whole, surfactant is able to improve oxygenation in infection related respiratory failure, pulmonary hemorrhage and meconium aspiration syndrome. Bronchoalveolar lavage with surfactant solution is currently the only means to reduce mortality or need for extracorporeal life support in neonates with meconium aspiration. While surfactant bolus or lavage only improves the oxygenation and ventilatory requirements in other types of postneonatal acute respiratory distress syndrome (ARDS), there seems to be a reduction in the mortality of small infants with RSV-related ARDS.

Activated carbon oxygen content influence on water and surfactant adsorption.

Science.gov (United States)

Pendleton, Phillip; Wu, Sophie Hua; Badalyan, Alexander

2002-02-15

This research investigates the adsorption properties of three activated carbons (AC) derived from coconut, coal, and wood origin. Each carbon demonstrates different levels of resistance to 2 M NaOH treatment. The coconut AC offers the greatest and wood AC the least resistance. The influence of base treatment is mapped in terms of its effects on specific surface area, micropore volume, water adsorption, and dodecanoic acid adsorption from both water and 2 M NaOH solution. A linear relationship exists between the number of water molecules adsorbed at the B-point of the water adsorption isotherm and the oxygen content determined from elemental analysis. Surfactant adsorption isotherms from water and 2 M NaOH indicate that the AC oxygen content effects a greater dependence on affinity for surfactant than specific surface area and micropore volume. We show a linear relationship between the plateau amount of surfactant adsorbed and the AC oxygen content in both water and NaOH phases. The higher the AC oxygen content, the lower the amount of surfactant adsorbed. In contrast, no obvious relationship could be drawn between the surfactant amount adsorbed and the surface area.

Interactions of a zwitterionic thiophene-based conjugated polymer with surfactants

DEFF Research Database (Denmark)

Costa, Telma; De Azevedo, Diego; Stewart, Beverly

2015-01-01

In this paper we investigate the optical and structural properties of a zwitterionic poly[3-(N-(4-sulfonato-1-butyl)-N,N-diethylammonium)hexyl-2,5-thiophene] (P3SBDEAHT) conjugated polyelectrolyte (CPE) and its interaction in water with surfactants, using absorption, photoluminescence (PL......), electrical conductivity, molecular dynamics simulations (MDS) and small-angle X-ray scattering (SAXS). Different surfactants were studied to evaluate the effect of the head group and chain length on the self-assembly. PL data emphasize the importance of polymer-surfactant electrostatic interactions...... in the formation of complexes. Nevertheless, conductivity and MDS data have shown that nonspecific interactions also play an important role. These seem to be responsible for the spatial position of the surfactant tail in the complex and, eventually, for breaking-up P3SBDEAHT aggregates. SAXS measurements on P3...

Effect of alkyl length of cationic surfactants on desorption of Cs from contaminated clay

Energy Technology Data Exchange (ETDEWEB)

Kim, Bo Hyun; Park, Chan Woo; Yang, Hee Man; Seo, Bum Kyoung; Lee, Kune Woo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Park, So Jin [Chungnam National University, Daejeon (Korea, Republic of)

2017-03-15

In this study, desorption characteristics of Cs from clay according to the hydrophobic alkyl chain length of the cationic surfactant were investigated. Alkyltrimethylammonium bromide was used as a cationic surfactant, and the length of the hydrophobic alkyl chain of the cationic surfactant was varied from –octyl to –cetyl. The adsorbed amount of the cationic surfactant on montmorillonite increased with the length of the hydrophobic alkyl chain, and intercalation of the cationic surfactant into the clay interlayer increased the interlayer distances. The Cs removal efficiency was also enhanced with increasing alkyl chain length, and the cationic surfactant with the cetyl group showed a maximum Cs removal efficiency of 99±2.9%.

(Surfactant + polymer) interaction parameter studied by (liquid + liquid) equilibrium data of quaternary aqueous solution containing surfactant, polymer, and salt

Energy Technology Data Exchange (ETDEWEB)

Foroutan, Masumeh [Physical Chemistry Department, School of Chemistry, College of Science, University of Tehran, 14155-6455 Tehran (Iran, Islamic Republic of)], E-mail: foroutan@khayam.ut.ac.ir; Heidari, Nosrat; Mohammadlou, Maryam [Chemistry Department, Faculty of Science, Uremia University, Uremia (Iran, Islamic Republic of); Sojahrood, Amin Jafari [Physics Department, Faculty of Science, Uremia University, Uremia (Iran, Islamic Republic of)

2009-02-15

(Liquid + liquid) equilibrium (LLE) data of quaternary aqueous system containing polyoxyethylene (20) cetyl ether (with abbreviation name Brij 58, non-ionic surfactant), diammonium hydrogen phosphate, and poly ethylene glycol (PEG) with three molar masses {l_brace}M{sub W} = (1000, 6000, and 35,000) g . mol{sup -1}{r_brace} have been determined experimentally at T = 313.15 K. Furthermore, the Flory-Huggins theory with two electrostatic terms (Debye-Hueckel and Pitzer-Debye-Hueckel equations) have been used to calculate the phase behavior of the quaternary systems and (surfactant + polymer) interaction parameter as well as interaction parameters between other species. Temperature dependency of the parameters of the Flory-Huggins theory has been obtained. Also an effort have been done to show that addition of PEG as well as increasing the temperature can shift the binodal curves of the ternary aqueous system containing surfactant and salt to lower mole fraction of salt. Also the effect of polymer molar mass on the binodal diagram displacement has been discussed.

The Effect of Surfactants on Gas-Liquid Pipe Flows

NARCIS (Netherlands)

Van Nimwegen, A.T.

2015-01-01

Liquid loading is a major problem in the natural gas industry, in which gas production is limited by the accumulation of liquids in the well tubing. Liquid loading can be prevented by the injection of surfactants at the bottom of the well. The surfactants cause the liquid in the well to foam,

Surfactant-nanotube interactions in water and nanotube separation by diameter: atomistic simulations

Science.gov (United States)

Carvalho, E. J. F.; Dos Santos, M. C.

2010-05-01

A non-destructive sorting method to separate single-walled carbon nanotubes (SWNTs) by diameter was recently proposed. By this method, SWNTs are suspended in water by surfactant encapsulation and the separation is carried out by ultracentrifugation in a density gradient. SWNTs of different diameters are distributed according to their densities along the centrifuge tube. A mixture of two anionic surfactants, namely sodium dodecylsulfate (SDS) and sodium cholate (SC), presented the best performance in discriminating nanotubes by diameter. Unexpectedly, small diameter nanotubes are found at the low density part of the centrifuge tube. We present molecular dynamics studies of the water-surfactant-SWNT system to investigate the role of surfactants in the sorting process. We found that surfactants can actually be attracted towards the interior of the nanotube cage, depending on the relationship between the surfactant radius of gyration and the nanotube diameter. The dynamics at room temperature showed that, as the amphiphile moves to the hollow cage, water molecules are dragged together, thereby promoting the nanotube filling. The resulting densities of filled SWNT are in agreement with measured densities.

Microwave-assisted nonionic surfactant extraction of aliphatic hydrocarbons from petroleum source rock

Energy Technology Data Exchange (ETDEWEB)

Akinlua, A., E-mail: geochemresearch@yahoo.com [Fossil Fuels and Environmental Geochemistry Group, Department of Chemistry, Obafemi Awolowo University, Ile-Ife (Nigeria); Jochmann, M.A.; Laaks, J.; Ewert, A.; Schmidt, T.C. [Instrumental Analytical Chemistry, University Duisburg-Essen, Universitaetsstr, 5, 45141 Essen (Germany)

2011-04-08

The extraction of aliphatic hydrocarbons from petroleum source rock using nonionic surfactants with the assistance of microwave was investigated and the conditions for maximum yield were determined. The results showed that the extraction temperatures and kinetic rates have significant effects on extraction yields of aliphatic hydrocarbons. The optimum temperature for microwave-assisted nonionic surfactant extraction of aliphatic hydrocarbons from petroleum source rock was 105 deg. C. The optimum extraction time for the aliphatic hydrocarbons was at 50 min. Concentration of the nonionic surfactant solution and irradiation power had significant effect on the yields of aliphatic hydrocarbons. The yields of the analytes were much higher using microwave assisted nonionic surfactant extraction than with Soxhlet extraction. The recoveries of the n-alkanes and acyclic isoprenoid hydrocarbons for GC-MS analysis from the extractant nonionic surfactant solution by in-tube extraction (ITEX 2) with a TENAX TA adsorbent were found to be efficient. The results show that microwave-assisted nonionic surfactant extraction (MANSE) is a good and efficient green analytical preparatory technique for geochemical evaluation of petroleum source rock.

Microwave-assisted nonionic surfactant extraction of aliphatic hydrocarbons from petroleum source rock

International Nuclear Information System (INIS)

Akinlua, A.; Jochmann, M.A.; Laaks, J.; Ewert, A.; Schmidt, T.C.

2011-01-01

The extraction of aliphatic hydrocarbons from petroleum source rock using nonionic surfactants with the assistance of microwave was investigated and the conditions for maximum yield were determined. The results showed that the extraction temperatures and kinetic rates have significant effects on extraction yields of aliphatic hydrocarbons. The optimum temperature for microwave-assisted nonionic surfactant extraction of aliphatic hydrocarbons from petroleum source rock was 105 deg. C. The optimum extraction time for the aliphatic hydrocarbons was at 50 min. Concentration of the nonionic surfactant solution and irradiation power had significant effect on the yields of aliphatic hydrocarbons. The yields of the analytes were much higher using microwave assisted nonionic surfactant extraction than with Soxhlet extraction. The recoveries of the n-alkanes and acyclic isoprenoid hydrocarbons for GC-MS analysis from the extractant nonionic surfactant solution by in-tube extraction (ITEX 2) with a TENAX TA adsorbent were found to be efficient. The results show that microwave-assisted nonionic surfactant extraction (MANSE) is a good and efficient green analytical preparatory technique for geochemical evaluation of petroleum source rock.

Surfactive stabilization of multi-walled carbon nanotube dispersions with dissolved humic substances

Energy Technology Data Exchange (ETDEWEB)

Chappell, Mark A. [Environmental Laboratory, Engineering Research and Development Center, US Army Corps of Engineers, 3909 Halls Ferry Road, Vicksburg, MS 39180 (United States)], E-mail: mark.a.chappell@usace.army.mil; George, Aaron J.; Dontsova, Katerina M.; Porter, Beth E. [SpecPro, Inc., 4815 Bradford Drive, Suite 201, Huntsville, AL 35805 (United States); Price, Cynthia L. [Environmental Laboratory, Engineering Research and Development Center, US Army Corps of Engineers, 3909 Halls Ferry Road, Vicksburg, MS 39180 (United States); Zhou Pingheng; Morikawa, Eizi [J. Bennett Johnston Sr. Center for Advanced Microstructures and Devices, Louisiana State University, 6980 Jefferson Highway, Baton Rouge, LA 70806 (United States); Kennedy, Alan J.; Steevens, Jeffery A. [Environmental Laboratory, Engineering Research and Development Center, US Army Corps of Engineers, 3909 Halls Ferry Road, Vicksburg, MS 39180 (United States)

2009-04-15

Soil humic substances (HS) stabilize carbon nanotube (CNT) dispersions, a mechanism we hypothesized arose from the surfactive nature of HS. Experiments dispersing multi-walled CNT in solutions of dissolved Aldrich humic acid (HA) or water-extractable Catlin soil HS demonstrated enhanced stability at 150 and 300 mg L{sup -1} added Aldrich HA and Catlin HS, respectively, corresponding with decreased CNT mean particle diameter (MPD) and polydispersivity (PD) of 250 nm and 0.3 for Aldrich HA and 450 nm and 0.35 for Catlin HS. Analogous trends in MPD and PD were observed with addition of the surfactants Brij 35, Triton X-405, and SDS, corresponding to surfactant sorption maximum. NEXAFS characterization showed that Aldrich HA contained highly surfactive domains while Catlin soil possessed a mostly carbohydrate-based structure. This work demonstrates that the chemical structure of humic materials in natural waters is directly linked to their surfactive ability to disperse CNT released into the environment. - Suspensions of multi-walled carbon nanotubes are stabilized by relatively low concentrations of dissolved humic substances in solution through surfactive mechanisms.

Surfactive stabilization of multi-walled carbon nanotube dispersions with dissolved humic substances

International Nuclear Information System (INIS)

Chappell, Mark A.; George, Aaron J.; Dontsova, Katerina M.; Porter, Beth E.; Price, Cynthia L.; Zhou Pingheng; Morikawa, Eizi; Kennedy, Alan J.; Steevens, Jeffery A.

2009-01-01

Soil humic substances (HS) stabilize carbon nanotube (CNT) dispersions, a mechanism we hypothesized arose from the surfactive nature of HS. Experiments dispersing multi-walled CNT in solutions of dissolved Aldrich humic acid (HA) or water-extractable Catlin soil HS demonstrated enhanced stability at 150 and 300 mg L -1 added Aldrich HA and Catlin HS, respectively, corresponding with decreased CNT mean particle diameter (MPD) and polydispersivity (PD) of 250 nm and 0.3 for Aldrich HA and 450 nm and 0.35 for Catlin HS. Analogous trends in MPD and PD were observed with addition of the surfactants Brij 35, Triton X-405, and SDS, corresponding to surfactant sorption maximum. NEXAFS characterization showed that Aldrich HA contained highly surfactive domains while Catlin soil possessed a mostly carbohydrate-based structure. This work demonstrates that the chemical structure of humic materials in natural waters is directly linked to their surfactive ability to disperse CNT released into the environment. - Suspensions of multi-walled carbon nanotubes are stabilized by relatively low concentrations of dissolved humic substances in solution through surfactive mechanisms

Increased drop formation frequency via reduction of surfactant interactions in flow-focusing microfluidic devices.

Science.gov (United States)

Josephides, Dimitris N; Sajjadi, Shahriar

2015-01-27

Glass capillary based microfluidic devices are able to create extremely uniform droplets, when formed under the dripping regime, at low setup costs due to their ease of manufacture. However, as they are rarely parallelized, simple methods to increase droplet production from a single device are sought. Surfactants used to stabilize drops in such systems often limit the maximum flow rate that highly uniform drops can be produced due to the lowering interfacial tension causing jetting. In this paper we show that by simple design changes we can limit the interactions of surfactants and maximize uniform droplet production. Three flow-focused configurations are explored: a standard glass capillary device (consisting of a single round capillary inserted into a square capillary), a nozzle fed device, and a surfactant shielding device (both consisting of two round capillaries inserted into either end of a square capillary). In principle, the maximum productivity of uniform droplets is achieved if surfactants are not present. It was found that surfactants in the standard device greatly inhibit droplet production by means of interfacial tension lowering and tip-streaming phenomena. In the nozzle fed configuration, surfactant interactions were greatly limited, yielding flow rates comparable to, but lower than, a surfactant-free system. In the surfactant shielding configuration, flow rates were equal to that of a surfactant-free system and could make uniform droplets at rates an order of magnitude above the standard surfactant system.

Screening and Optimization of Bio surfactant Production by the Hydrocarbon-Degrading Bacteria

International Nuclear Information System (INIS)

Ainon Hamzah; Noramiza Sabturani; Shahidan Radiman

2013-01-01

Bio surfactants are amphiphilic compounds produced by microorganisms as secondary metabolite. The unique properties of bio surfactants make them possible to replace or to be added to synthetic surfactants which are mainly used in food, cosmetics and pharmaceutical industries and in environmental applications. In this study twenty hydrocarbon-degrading bacteria were screened for bio surfactant production. All of the bacterial isolates were grown in mineral salt medium (MSM) with addition of 1 % (v/v) Tapis crude oil as carbon source. The presence of bio surfactant was determined by the drop-collapse test, microplate analysis, oil spreading technique, emulsification index (%EI24) and surface tension measurement. Only one isolate, Pseudomonas aeruginosa UKMP14T, was found to be positive for all the qualitative tests and reducing the surface tension of the medium to 49.5 dynes/ with emulsification index of 25.29 %. This isolate produced bio surfactant optimally at pH 9.0 and incubation temperature of 37 degree Celsius. Furthermore, P. aeruginosa UKMP14T when grown in MSM with addition of 1 % (v/v) glycerol and 1.3 g/ L ammonium sulphate with C/N ratio 14:1 produced bio surfactant with percentage of surface tension reduction at 55 % or 30.6 dynes/ cm with %EI24 of 43 %. This percentage of surface tension reduction represents an increasing reduction in surface tension of medium by 39 % over the value before optimization. This study showed that P. aeruginosa UKMP14T has the ability to biodegrade hydrocarbon and concurrently produce bio surfactant. (author)

Study of surfactant-free microemulsions and microemulsions with fatty acid salts

OpenAIRE

Marcus, Julien

2016-01-01

This thesis deals with the study of microemulsions and is composed of two main parts. In the first part, surfactant-free microemulsions are studied, whereas in the second part microemulsions with surfactants and cosurfactants are investigated. Over the last few years, surfactant-free microemulsions became a major topic at our institute and were thoroughly studied using the reference system water/ethanol/1-octanol. As explained later in the Fundamentals part (see section 1.2), fluctuating ...

Interaction of biocompatible natural rosin-based surfactants with human serum albumin: A biophysical study

Energy Technology Data Exchange (ETDEWEB)

Ishtikhar, Mohd [Protein Biophysics Laboratory, Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202002 (India); Ali, Mohd Sajid [Surfactant Research Chair, Department of Chemistry, King Saud University, P.O. Box-2455, Riyadh 11451 (Saudi Arabia); Atta, Ayman M. [Surfactant Research Chair, Department of Chemistry, King Saud University, P.O. Box-2455, Riyadh 11451 (Saudi Arabia); Petroleum Application department, Egyptian Petroleum Research Institute, Ahmad Elzomor St., Nasr city, Cairo-11727 (Egypt); Al-Lohedan, H.A. [Surfactant Research Chair, Department of Chemistry, King Saud University, P.O. Box-2455, Riyadh 11451 (Saudi Arabia); Nigam, Lokesh; Subbarao, Naidu [Centre for Computational Biology and Bioinformatics, School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi 110067 (India); Hasan Khan, Rizwan, E-mail: rizwanhkhan@hotmail.com [Protein Biophysics Laboratory, Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202002 (India)

2015-11-15

Biophysical insight into interaction of biocompatible rosin-based surfactants with human serum albumin (HSA) was studied at physiological conditions using various spectroscopic, calorimetric and molecular docking approaches. The binding constant (K{sub b}), enthalpy (ΔH{sup 0}), entropy (ΔS{sup 0}) and Gibbs free energy change (ΔG{sup 0}) were calculated by spectroscopic and calorimetric method. We have also calculated the probability of energy transfer by FRET analysis. The circular dichroism study showed that the cationic surfactant QRMAE significantly altered the secondary structure of HSA as compared to the nonionic rosin surfactants. The thermodynamic study was performed by ITC to determine binding constant as well as change in enthalpy of HSA in presence of rosin surfactants. It clearly showed that hydrogen binding and hydrophobic interaction play an important role in the binding of HSA to rosin surfactants. We have also performed molecular docking studies to locate the binding site on HSA and to visualize the mode of interaction. The present study provides a significant insight into HSA–rosin surfactants interaction, which also improves our understanding of the possible effect of rosin surfactants on human health. - Highlights: • RMPEG 750 has the highest Kb, Kq and Ksv value as compared to other rosin surfactants. • The probability of energy transfer from HSA to rosin surfactants was maximum in the case of RMPEG 750. • Cationic surfactant QRMAE significantly altered the secondary structure of the HSA as compared to other rosin surfactants. • Molecular docking and ITC experiment studies, to locate the binding site on HSA and to investigate the mode of interaction.

Surfactant Apoprotein D in Preterm Neonates with Acute Respiratory Distress Syndrome

Directory of Open Access Journals (Sweden)

S. A. Perepelitsa

2009-01-01

Full Text Available Objective: to study the production of surfactant apoprotein D in preterm neonates with acute respiratory distress syndrome (ARDS during artificial ventilation (AV. Subjects and methods. The paper presents the results of studying the production of surfactant protein D (SP-D in various biological fluids in 44 preterm neonates. Two groups of newborn infants were identified according to the clinical manifestations of ARDS. The study group comprised 25 infants with the severe course of the disease, in this connection the preventive administration of the exogenous surfactant Curosurf and AV were made in all the neonates at birth. The control group included 19 preterm babies without signs of ARDS. Results. The study has demonstrated that in parturients and preterm neonatal infants, surfactant apoprotein D is detectable in various biological fluids: amniotic fluid, the gastric aspirate obtained just after birth, residual umbilical cord blood, serum following 8 hours of birth, and bronchoalveolar fluid. Despite the low gestational age of the neonates, the lung surfactant system is able to produce SP-D, as evidenced by its high content in the amniotic fluid and residual umbilical cord blood of preterm neonates. The production of apoprotein D in preterm neonates considerably reduces in the next few hours after birth. Conclusion. The findings suggest that fetal tissues generate SP-D, which improves pulmonary gas exchange in preterm neonates in the first hours after birth and that alveolar-capillary membrane dysfunctions are transient in the neonates on AV. Key words: preterm neonates, acute respiratory distress syndrome, surfactant, surfactant apoprotein D.

The effect of pressure on the phase behavior of surfactant systems: An experimental study

DEFF Research Database (Denmark)

Sandersen, Sara Bülow; Stenby, Erling Halfdan; von Solms, Nicolas

2012-01-01

Enhanced oil recovery is employed in many mature oil reservoirs to maintain or increase the reservoir recovery factor. In this context, surfactant flooding has recently gained interest again. Surfactant flooding is the injection of surfactants (and co-surfactants) into the reservoir, in order...... to create microemulsions at the interface between crude oil and water, thus obtaining very low interfacial tension, which consequently helps mobilize the trapped oil.In this work a surfactant system, which has been thoroughly described at atmospheric pressure, is examined at elevated pressure. The effect...

Adsorption of surfactants on sand surface in enhanced oil recovery: Isotherms, kinetics and thermodynamic studies

Energy Technology Data Exchange (ETDEWEB)

Bera, Achinta; Kumar, T.; Ojha, Keka; Mandal, Ajay, E-mail: mandal_ajay@hotmail.com

2013-11-01

Adsorption of surfactants onto reservoir rock surface may result in the loss and reduction of their concentrations in surfactant flooding, which may render them less efficient or ineffective in practical applications of enhanced oil recovery (EOR) techniques. Surfactant flooding for EOR received attraction due to its ability to increase the displacement efficiency by lowering the interfacial tension between oil and water and mobilizing the residual oil. This article highlights the adsorption of surfactants onto sand surface with variation of different influencing factors. It has been experimentally found that adsorption of cationic surfactant on sand surface is more and less for anionic surfactant, while non-ionic surfactant shows intermediate behaviour. X-ray diffraction (XRD) study of clean sand particles has been made to determine the main component present in the sand particles. The interaction between sand particles and surfactant has been studied by Fourier Transform Infrared (FTIR) Spectroscopy of the sand particles before and after aging with surfactant. Salinity plays an important role in adsorption of anionic surfactant. Batch experiments were also performed to understand the effects of pH and adsorbent dose on the sorption efficiency. The sand particles exhibited high adsorption efficiency at low pH for anionic and nonionic surfactants. But opposite trend was found for cationic surfactant. Adsorption data were analyzed by fitting with Langmuir, Freundlich, Redlich-Peterson, and Sips isotherm models. Results show that the Langmuir isotherm and pseudo-second order kinetics models suit the equilibrium and kinetics of adsorption on sand surface. Thermodynamics feasibility of the adsorption process was also studied to verify the spontaneity of the process.

Evaluation of bacterial surfactant toxicity towards petroleum degrading microorganisms.

Science.gov (United States)

Lima, Tânia M S; Procópio, Lorena C; Brandão, Felipe D; Leão, Bruna A; Tótola, Marcos R; Borges, Arnaldo C

2011-02-01

The acute toxicity of bacterial surfactants LBBMA111A, LBBMA155, LBBMA168, LBBMA191 and LBBMA201 and the synthetic surfactant sodium dodecyl sulfate (SDS) on the bioluminescent bacterium Vibrio fischeri was evaluated by measuring the reduction of light emission (EC(20)) by this microorganism when exposed to different surfactant concentrations. Moreover, the toxic effects of different concentrations of biological and synthetic surfactants on the growth of pure cultures of isolates Acinetobacter baumannii LBBMA04, Acinetobacter junni LBBMA36, Pseudomonas sp. LBBMA101B and Acinetobacter baumanni LBBMAES11 were evaluated in mineral medium supplemented with glucose. The EC(20) values obtained confirmed that the biosurfactants have a significantly lower toxicity to V. fischeri than the SDS. After 30 min of exposure, bacterial luminescence was almost completely inhibited by SDS at a concentration of 4710 mg L(-1). Growth reduction of pure bacterial cultures caused by the addition of biosurfactants to the growth medium was lower than that caused by SDS. Copyright © 2010 Elsevier Ltd. All rights reserved.

Factors affecting responses of infants with respiratory distress syndrome to exogenous surfactant therapy.

Science.gov (United States)

Ho, N K

1993-02-01

Approximately 20% to 30% of infants with respiratory distress syndrome (RDS) do not respond to surfactant replacement therapy. Unfortunately there is no uniform definition of 'response' or 'non-response' to surfactant therapy. Response was based on improvement in a/A PO2 and/or mean airway pressure (MAP) by some and on improvement in FIO2 and/or MAP by others. Even the point of time at which evaluation of response was done is different in various reports. There is an urgent need to adopt an uniform definition. Most premature babies are surfactant deficient which is the aetiological factor of RDS. Generally good antenatal care and perinatal management are essential in avoidance of premature birth. Babies with lung hypoplasia and who are extremely premature (less than 24 weeks of gestation) do not respond well to exogenous surfactant replacement because of structural immaturity. Prompt management of asphyxiated birth and shock are necessary as there may be negative response to surfactant replacement. Foetal exposure to glucocorticoids improves responsiveness to postnatal administration of surfactant. Antenatal steroid therapy has become an important part of management of RDS with surfactant replacement. The premature lungs with high alveolar permeability tend to develop pulmonary oedema. With the presence of plasma-derived surfactant inhibitors, the response to exogenous surfactant may be affected. These inhibitors may also be released following ventilator barotrauma. The standard of neonatal intensive care such as ventilatory techniques has an important bearing on the outcome of the RDS babies.(ABSTRACT TRUNCATED AT 250 WORDS)

Growth Mechanism of Gold Nanorods in Binary Surfactant System

Energy Technology Data Exchange (ETDEWEB)

Kim, Bo-Mi; Seo, Sun-Hwa; Joe, Ara; Shim, Kyu-Dong; Jang, Eue-Soon [Kumoh National Institute of Technology, Gumi (Korea, Republic of)

2016-06-15

In order to reveal the growth mechanism of gold nanorods (GNRs) in a binary surfactant system, we synthesized various GNRs by changing the concentration of the surfactants, AgNO{sub 3}, and HBr in the growth solution. We found that the benzyldime thylhexadecylammoniumchloride surfactant had weak interaction with the gold ions, but it could reduce the membrane fluidity. In addition, we could dramatically decrease the cetyltrimethylammonium bromide concentration required for GNR growth by adding an HBr solution. Notably, Ag{sup +} ions were necessary to break the symmetry of the seed crystals for GNR growth, but increasing the concentration of Ag{sup +} and Br{sup -} ions caused a decrease in the template size.

Atomistic simulations of surfactant adsorption kinetics at interfaces

Science.gov (United States)

Iskrenova, Eugeniya; Patnaik, Soumya

2014-03-01

Heat transfer control and enhancement is an important and challenging problem in a variety of industrial and technological applications including aircraft thermal management. The role of additives in nucleate boiling and phase change in general has long been recognized and studied experimentally and modeled theoretically but in-depth description and atomistic understanding of the multiscale processes involved are still needed for better prediction and control of the heat transfer efficiency. Surfactant additives have been experimentally observed to either enhance or inhibit the boiling heat transfer depending on the surfactant concentration and chemistry and, on a molecular level, their addition leads to dynamic surface tension and changes in interfacial and transfer properties, thus contributing to the complexity of the problem. We present our atomistic modeling study of the interfacial adsorption kinetics of aqueous surfactant (sodium dodecyl sulfate) systems at a range of concentrations at room and boiling temperatures. Classical molecular dynamics and Umbrella Sampling simulations were used to study the surfactant transport properties and estimate the adsorption and desorption rates at liquid-vacuum and liquid-solid interfaces. The authors gratefully acknowledge funding from AFOSR Thermal Science Program and the Air Force Research Laboratory DoD Supercomputing Resource Center for computing time and resources.

Effect of Surfactants on Plasmid DNA Stability and Release from ...

African Journals Online (AJOL)

Purpose: To evaluate the effect of surfactants on plasmid DNA during preparation and release from polylactic glycolide (PLGA) microspheres. Methods: Various surfactants, both ionic and non-ionic (Span, Tween, Triton X100, cetyltrimethylammonium bromide and sodium dodecyl sulphate), were added during the ...

Spectral behaviour of eosin Y in different solvents and aqueous surfactant media

Science.gov (United States)

Chakraborty, Moumita; Panda, Amiya Kumar

2011-10-01

Photophysical behaviour of the anionic xanthene dye, eosin Y (EY) was investigated in solvents of different polarities as well as in the presence of aqueous cationic surfactants. From the correlation between ET(30) and Kosower Z values of EY in different solvents, subsequent parameters for EY were determined in the presence of surfactants. A red shift, both in the absorption and emission spectra of EY, was observed with decreasing solvent polarity. Dimerisation of EY was found to be dependent on solvent polarity. Cationic surfactants retarded the process of dimerisation, which were evident from the lower dimerisation constant ( KD) values, compared to that of in pure water. Dye-surfactant interaction constants were determined at different temperatures (298-318 K) and subsequently the thermodynamic parameters, viz., Δ G°, Δ H° and Δ S° were evaluated using the interaction constant values. The fluorescence spectra of EY followed the same trend as in the absorption spectra, although with lesser extents. Stokes shifts were calculated and correlated with the polarity of the medium. Fluorescence of EY was initially quenched by the cationic surfactants in their pre-micellar region, which then followed a red shift with intensity enhancement. Fluorescence quenching was found to be of Stern-Volmer type where the excited state lifetime of EY remained unchanged in different surfactant media. However, the anisotropy value of EY was changed in the post micellar region of surfactants.

Mathematical Modelling of Surfactant Self-assembly at Interfaces

KAUST Repository

Morgan, C. E.

2015-01-01

© 2015 Society for Industrial and Applied Mathematics. We present a mathematical model to describe the distribution of surfactant pairs in a multilayer structure beneath an adsorbed monolayer. A mesoscopic model comprising a set of ordinary differential equations that couple the rearrangement of surfactant within the multilayer to the surface adsorption kinetics is first derived. This model is then extended to the macroscopic scale by taking the continuum limit that exploits the typically large number of surfactant layers, which results in a novel third-order partial differential equation. The model is generalized to allow for the presence of two adsorbing boundaries, which results in an implicit free-boundary problem. The system predicts physically observed features in multilayer systems such as the initial formation of smaller lamellar structures and the typical number of layers that form in equilibrium.

Coupling the Alkaline-Surfactant-Polymer Technology and The Gelation Technology to Maximize Oil Production

Energy Technology Data Exchange (ETDEWEB)

Malcolm Pitts; Jie Qi; Dan Wilson; Phil Dowling; David Stewart; Bill Jones

2005-12-01

Gelation technologies have been developed to provide more efficient vertical sweep efficiencies for flooding naturally fractured oil reservoirs or reservoirs with different sand lenses with high permeability contrast. The field proven alkaline-surfactant-polymer technology economically recovers 15% to 25% OOIP more crude oil than waterflooding from swept pore space of an oil reservoir. However, alkaline-surfactant-polymer technology is not amenable to naturally fractured reservoirs or reservoirs with high permeability contrast zones because much of injected solution bypasses target pore space containing oil. This work investigates whether combining these two technologies could broaden applicability of alkaline-surfactant-polymer flooding into these reservoirs. Fluid-fluid interaction with different gel chemical compositions and alkaline-surfactant-polymer solution with pH values ranging from 9.2 to 12.9 have been tested. Aluminum-polyacrylamide gels are not stable to alkaline-surfactant-polymer solutions at any pH. Chromium-polyacrylamide gels with polymer to chromium ion ratios of 25 or greater were stable to alkaline-surfactant-polymer solutions if solution pH was 10.6 or less. When the polymer to chromium ion was 15 or less, chromium-polyacrylamide gels were stable to alkaline-surfactant-polymer solutions with pH values up to 12.9. Chromium-xanthan gum gels were stable to alkaline-surfactant-polymer solutions with pH values of 12.9 at the polymer to chromium ion ratios tested. Silicate-polyacrylamide, resorcinol-formaldehyde, and sulfomethylated resorcinol-formaldehyde gels were also stable to alkaline-surfactant-polymer solutions with pH values ranging from 9.2 to 12.9. Iron-polyacrylamide gels were immediately destroyed when contacted with any of the alkaline-surfactant-polymer solutions with pH values ranging from 9.2 to 12.9. Gel solutions under dynamic conditions of linear corefloods showed similar stability to alkaline-surfactant-polymer solutions as in

Molecular self assembly of mixed comb-like dextran surfactant polymers for SPR virus detection.

Science.gov (United States)

Mai-Ngam, Katanchalee; Kiatpathomchai, Wansika; Arunrut, Narong; Sansatsadeekul, Jitlada

2014-11-04

The synthesis of two comb-like dextran surfactant polymers, that are different in their dextran molecular weight (MW) distribution and the presence of carboxylic groups, and their characterization are reported. A bimodal carboxylic dextran surfactant polymer consists of poly(vinyl amine) (PVAm) backbone with carboxyl higher MW dextran, non-functionalized lower MW dextran and hydrophobic hexyl branches; while a monomodal dextran surfactant polymer is PVAm grafted with non-functionalized lower MW dextran and hexyl branches. Layer formation of non-covalently attached dextran chains with bimodal MW distributions on a surface plasmon resonance (SPR) chip was investigated from the perspective of mixed physisorption of the bimodal and monomodal surfactant polymers. Separation distances between the carboxylic longer dextran side chains within the bimodal surfactant polymer and between the whole bimodal surfactant molecules on the chip surface could be well-controlled. SPR analysis of shrimp yellow head virus using our mixed surfactant chips showed dependence on synergetic adjustment of these separation distances. Copyright © 2014 Elsevier Ltd. All rights reserved.

μ-Hexa­thio­metadiphosphato-bis­[(1,4,7,10,13,16-hexa­oxa­cyclo­octa­decane-κ6 O)rubidium] aceto­nitrile disolvate

Science.gov (United States)

Gjikaj, Mimoza; Pook, Niels-Patrick; Qarri, Flora

2013-01-01

The asymmetric unit of the title compound, [Rb2(P2S6)(C12H24O6)2]·2CH3CN, contains one half of an [Rb(18-crown-6)2]2[P2S6] unit and one aceto­nitrile solvent mol­ecule. The [Rb(18-crown-6)]2[P2S6] unit is completed by inversion symmetry. Its Rb+ ion is situated near the centre of the macrocyclic cavity, but is displaced by 0.8972 (1) Å from the O atoms of the crown in the direction of the [P2S6]2− moiety. The overall coordination number of the cation is eight, defined by the six crown ether O atoms and by two terminal S atoms of the [P2S6]2− anion. The hexa­thio­metadiphosphate anion is built up from two tetra­hedral PS4 units joined together by a common edge. The crystal structure is characterized by alternating layers of [Rb(18-crown-6)]2[P2S6] and aceto­nitrile solvent mol­ecules stacked along [010]. PMID:24860286

Small-angle neutron scattering studies of nonionic surfactant: Effect

Indian Academy of Sciences (India)

Micellar solution of nonionic surfactant -dodecyloligo ethyleneoxide surfactant, decaoxyethylene monododecyl ether [CH3(CH2)11(OCH2CH2)10OH], C12E10 in D2O solution have been analysed by small-angle neutron scattering (SANS) at different temperatures (30, 45 and 60°C) both in the presence and absence of ...

Removal of cationic surfactant (CTAB from aqueous solution on to activated carbon obtained from corncob.

Directory of Open Access Journals (Sweden)

S. M. Yakout

2009-05-01

Full Text Available Direct and indirect releases of large quantities of surfactants to the environment may result in serious health and environmental problems. Therefore, surfactants should be removed from water before water is released to the environment or delivered for public use. Using powdered activated carbon (PAC as adsorbent may be an effective technique to remove surfactants. In this study, the removal of surfactants by PAC was investigated and the influencesof the operating parameters on the effectiveness on adsorption rate were studied. Cationic surfactant, Cetyl trimethyl ammonium bromide (CTAB was selected for the experiments. A series of batch experiments were performed to determine the sorption isotherms of surfactants to PAC. The results showed that carbon structure affect mainly on the surfactant adsorption. Surfactant equilibrium data fitted very well to the binary langmuir model. The pseudo first-,second- order and intraparticle diffusion kinetic models were applied. Both, the external mass transfer and intraparticle diffusion mechanisms involve in CTAB sorption.

Composition, structure and mechanical properties define performance of pulmonary surfactant membranes and films

DEFF Research Database (Denmark)

Ortiz, Elisa Parra; Perez-Gil, Jesús

2015-01-01

of breathing and avoiding alveolar collapse, especially at the end of expiration. The goal of the present review is to summarize current knowledge regarding the structure, lipid-protein interactions and mechanical features of surfactant membranes and films and how these properties correlate with surfactant...... biological function inside the lungs. Surfactant mechanical properties can be severely compromised by different agents, which lead to surfactant inhibition and ultimately contributes to the development of pulmonary disorders and pathologies in newborns, children and adults. A detailed comprehension...

Dicationic alkylammonium bromide gemini surfactants. Membrane perturbation and skin irritation.

Directory of Open Access Journals (Sweden)

João A S Almeida

Full Text Available Dicationic alkylammonium bromide gemini surfactants represent a class of amphiphiles potentially effective as skin permeation enhancers. However, only a limited number of studies has been dedicated to the evaluation of the respective cytotoxicity, and none directed to skin irritation endpoints. Supported on a cell viability study, the cytotoxicity of gemini surfactants of variable tail and spacer length was assessed. For this purpose, keratinocyte cells from human skin (NCTC 2544 cell line, frequently used as a model for skin irritation, were employed. The impact of the different gemini surfactants on the permeability and morphology of model vesicles was additionally investigated by measuring the leakage of calcein fluorescent dye and analyzing the NMR spectra of ³¹P, respectively. Detail on the interaction of gemini molecules with model membranes was also provided by a systematic differential scanning calorimetry (DSC and molecular dynamics (MD simulation. An irreversible impact on the viability of the NCTC 2544 cell line was observed for gemini concentrations higher than 25 mM, while no cytotoxicity was found for any of the surfactants in a concentration range up to 10 mM. A higher cytotoxicity was also found for gemini surfactants presenting longer spacer and shorter tails. The same trend was obtained in the calorimetric and permeability studies, with the gemini of longest spacer promoting the highest degree of membrane destabilization. Additional structural and dynamical characterization of the various systems, obtained by ³¹P NMR and MD, provide some insight on the relationship between the architecture of gemini surfactants and the respective perturbation mechanism.

Effect of selected non-ionic surfactants on the flow behavior of aqueous veegum suspensions.

Science.gov (United States)

Kennedy, Ross A; Kennedy, Michelle L

2007-03-30

The aim of this work was to investigate the influence of some non-ionic surfactants, Tween 80 and Brij 98, on the viscosity and flow behavior of a commercial montmorillonite clay, Veegum Granules. The effect of different concentrations of the surfactants on the shear stress-shear rate rheograms of hydrated concentrated clay suspensions was determined by shear viscometry. The addition of either surfactant increased the plastic viscosity and the yield stress of the suspensions. Furthermore, both surfactants altered the thixotropy of the suspensions to an extent that depended on both the surfactant concentration and the time of equilibration of the surfactant and Veegum. Brij 98 had a greater and more rapid effect. It is proposed that the surfactant polar head-groups anchor at the tetrahedral sheet surface, leaving the alkyl chains extending away from the edges and faces. Consequently, the alkyl chains undergo hydrophobic interactions that facilitate the association between the platelets and increase the physical structure within the suspension. Stereochemical differences between the polar groups may lead to differences in the way the surfactants associate with the tetrahedral sheet and hence their ultimate effect on the rheological behavior. There is a significant interaction between these surfactants and montmorillonite clays, and the rheological changes that occur could have a major impact on any pharmaceutical formulation that uses these ingredients.

Contrast media inhibit exogenous surfactant therapy in rats with acute respiratory distress syndrome

NARCIS (Netherlands)

Kesecioglu, Jozef; Haitsma, Jack J.; Schultz, Marcus J.; den Heeten, Gerard J.; Lachmann, Burkhard

2006-01-01

AIM: To test the effects of various contrast media on the pulmonary surfactant system. MATERIAL AND METHODS: In a rat model of acute respiratory distress syndrome (ARDS) induced by lung lavage, the effects of surfactant suspended in saline were compared with surfactant suspended in the contrast

Essential Regulation of Lung Surfactant Homeostasis by the Orphan G Protein-Coupled Receptor GPR116

Directory of Open Access Journals (Sweden)

Mi Young Yang

2013-05-01

Full Text Available GPR116 is an orphan seven-pass transmembrane receptor whose function has been unclear. Global disruption of the Gpr116 gene in mice revealed an unexpected, critical role for this receptor in lung surfactant homeostasis, resulting in progressive accumulation of surfactant lipids and proteins in the alveolar space, labored breathing, and a reduced lifespan. GPR116 expression analysis, bone marrow transplantation studies, and characterization of conditional knockout mice revealed that GPR116 expression in ATII cells is required for maintaining normal surfactant levels. Aberrant packaging of surfactant proteins with lipids in the Gpr116 mutant mice resulted in compromised surfactant structure, function, uptake, and processing. Thus, GPR116 plays an indispensable role in lung surfactant homeostasis with important ramifications for the understanding and treatment of lung surfactant disorders.

Enhanced oil recovery with surfactant flooding

Energy Technology Data Exchange (ETDEWEB)

Buelow Sandersen, S.

2012-05-15

Understanding the underlying mechanisms of systems that exhibit liquid-liquid equilibrium (e.g. oil-brine systems) at reservoir conditions is an area of increasing interest within EOR. This is true both for complex surfactant systems as well as for oil and brine systems. It is widely accepted that an increase in oil recovery can be obtained through flooding, whether it is simple waterflooding, waterflooding where the salinity has been modified by the addition or removal of specific ions (socalled ''smart'' waterflooding) or surfactant flooding. High pressure experiments have been carried out in this work on a surfactant system (surfactant/ oil/ brine) and on oil/ seawater systems (oil/ brine). The high pressure experiments were carried out on a DBR JEFRI PVT cell, where a glass window allows observation of the phase behavior of the different systems at various temperatures and pressures inside the high pressure cell. Phase volumes can also be measured visually through the glass window using precision equipment. The surfactant system for which an experimental study was carried out consisted of the mixture heptane, sodium dodecyl sulfate (SDS)/ 1-butanol/ NaCl/ water. This system has previously been examined at ambient pressures and temperatures but this has been extended here to pressures up to 400 bar and to slightly higher temperatures (40 deg. C, 45 deg. C and 50 deg. C). Experiments were performed at constant salinity (6.56 %), constant surfactant-alcohol ratio (SAR) but with varying water-oil ratios (WOR). At all temperatures it was very clear that the effect of pressure was significant. The system changed from the two phase region, Winsor II, to the three phase region, Winsor III, as pressure increased. Increasing pressures also caused a shift from the three phase region (Winsor III), to a different two phase region, (Winsor I). These changes in equilibrium phase behavior were also dependent on the composition of the system. A number of

Effect of surfactant for magnetic properties of iron oxide nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Haracz, S. [Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89B, 61-614 Poznań (Poland); Hilgendorff, M. [Freie Universität Berlin, Fachbereich Physik, Arnimalle 14, 14195 Berlin (Germany); Rybka, J.D. [Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89B, 61-614 Poznań (Poland); Giersig, M. [Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89B, 61-614 Poznań (Poland); Freie Universität Berlin, Fachbereich Physik, Arnimalle 14, 14195 Berlin (Germany)

2015-12-01

Highlights: • Dynamic behavior of magnetic nanoparticles. • Synthesis of iron oxide nanoparticles. • Effect of surfactant for magnetic properties. - Abstract: For different medical applications nanoparticles (NPs) with well-defined magnetic properties have to be used. Coating ligand can change the magnetic moment on the surface of nanostructures and therefore the magnetic behavior of the system. Here we investigated magnetic NPs in a size of 13 nm conjugated with four different kinds of surfactants. The surface anisotropy and the magnetic moment of the system were changed due to the presence of the surfactant on the surface of iron oxide NPs.

An association between diet quality index for Koreans (DQI-K) and total mortality in Health Examinees Gem (HEXA-G) study.

Science.gov (United States)

Lim, Jiyeon; Lee, Yunhee; Shin, Sangah; Lee, Hwi-Won; Kim, Claire E; Lee, Jong-Koo; Lee, Sang-Ah; Kang, Daehee

2018-06-01

Diet quality scores or indices, based on dietary guidelines, are used to summarize dietary intake into a single numeric variable. The aim of this study was to examine the association between the modified diet quality index for Koreans (DQI-K) and mortality among Health Examinees-Gem (HEXA-G) study participants. The DQI-K was modified from the original diet quality index. A total of 134,547 participants (45,207 men and 89,340 women) from the HEXA-G study (2004 and 2013) were included. The DQI-K is based on eight components: 1) daily protein intake, 2) percent of energy from fat, 3) percent of energy from saturated fat, 4) daily cholesterol intake, 5) daily whole-grain intake, 6) daily fruit intake, 7) daily vegetable intake, and 8) daily sodium intake. The association between all-cause mortality and the DQI-K was examined using Cox proportional hazard regression models. Hazard ratios and confidence intervals were estimated after adjusting for age, gender, income, smoking status, alcohol drinking, body mass index, and total energy intake. The total DQI-K score was calculated by summing the scores of the eight components (range 0-9). In the multivariable adjusted models, with good diet quality (score 0-4) as a reference, poor diet quality (score 5-9) was associated with an increased risk of all-cause mortality (hazard ratios = 1.23, 95% confidence intervals = 1.06-1.43). Moreover, a one-unit increase in DQI-K score resulted in a 6% higher mortality risk. A poor diet quality DQI-K score was associated with an increased risk of mortality. The DQI-K in the present study may be used to assess the diet quality of Korean adults.

Molecular characterization of a novel HEXA mutation at the +3 position of intron 8 in a Tay-Sachs disease patient

Energy Technology Data Exchange (ETDEWEB)

Richard, M.; Triggs-Raine, B. [Univ. of Manitoba, Winnipeg (Canada); Natowicz, M. [E.K. Shriver Center, Waltham, MA (United States)

1994-09-01

Tay-Sachs disease is an autosomal recessive lysosomal storage disorder resulting from mutations in the HEXA gene that cause a deficiency in the activity of that enzyme {beta}-hexosaminidase A (Hex A). This deficiency leads to the build-up of G{sub M2} ganglioside, resulting in neurodegeneration and death. Biochemical analysis of a non-Jewish patient with a late-infantile form of Tay-Sachs disease revealed a substantial level of Hex A activity (38.4%) when 4-MUG was used as the substrate. However, when a substrate (4-MUGS) specific for the {alpha}-subunit of Hex A ({alpha}{beta}) was used, almost no activity was detected in the HEXA gene of the patient using SSCP analysis followed by sequencing. The first mutation, a G533A substitution in exon 5, is previously described and associated with the B1 form of Tay-Sachs disease. The second mutation is a novel a-to-g base change at the +3 position of intron 8. This was confirmed using the AIRS method, whereby a MaeIII site was created in the presence of the mutation. Normal and patient mRNA was reverse transcribed and exons 7 to 9 were PCR-amplified from the cDNA. An abnormally sized amplification product detected only in the patient cDNA was sequenced; exon 8 had been deleted and exons 7 and 9 were spliced together. A substantial level of normally-sized PCR product was also detected in the patient`s cDNA. Experiments are in progress to determine if this is produced from the allele harboring the G533A mutation. Given that previous mutations of this type have been associated with 97-100% abnormal splicing, this mutation is likely to be the cause, together with the G533A mutation, of Tay-Sachs disease in this patient.

Coupling the Alkaline-Surfactant-Polymer Technology and the Gelation Technology to Maximize Oil Production

Energy Technology Data Exchange (ETDEWEB)

Malcolm Pitts; Jie Qi; Dan Wilson; Phil Dowling; David Stewart; Bill Jones

2005-12-01

Gelation technologies have been developed to provide more efficient vertical sweep efficiencies for flooding naturally fractured oil reservoirs or reservoirs with different sand lenses with high permeability contrast. The field proven alkaline-surfactant-polymer technology economically recovers 15% to 25% OOIP more crude oil than waterflooding froin swept pore space of an oil reservoir. However, alkaline-surfactant-polymer technology is not amenable to naturally fractured reservoirs or reservoirs with high permeability contrast zones because much of injected solution bypasses target pore space containing oil. This work investigates whether combining these two technologies could broaden applicability of alkaline-surfactant-polymer flooding into these reservoirs. Fluid-fluid interaction with different gel chemical compositions and alkaline-surfactant-polymer solution with pH values ranging from 9.2 to 12.9 have been tested. Aluminum-polyacrylamide gels are not stable to alkaline-surfactant-polymer solutions at any pH. Chromium-polyacrylamide gels with polymer to chromium ion ratios of 25 or greater were stable to alkaline-surfactant-polymer solutions if solution pH was 10.6 or less. When the polymer to chromium ion was 15 or less, chromium-polyacrylamide gels were stable to alkaline-surfactant-polymer solutions with pH values up to 12.9. Chromium-xanthan gum gels were stable to alkaline-surfactant-polymer solutions with pH values of 12.9 at the polymer to chromium ion ratios tested. Silicate-polyacrylamide, resorcinol-formaldehyde, and sulfomethylated resorcinol-formaldehyde gels were also stable to alkaline-surfactant-polymer solutions with pH values ranging from 9.2 to 12.9. Iron-polyacrylamide gels were immediately destroyed when contacted with any of the alkaline-surfactant-polymer solutions with pH values ranging from 9.2 to 12.9. Gel solutions under dynamic conditions of linear corefloods showed similar stability to alkaline-surfactant-polymer solutions as in

Interactions of short chain phenylalkanoic acids within ionic surfactant micelles in aqueous media

Directory of Open Access Journals (Sweden)

Naeem Kashif

2012-01-01

Full Text Available % SDS KR nema Solubilization and interactions of phenylalkanoic acids induced by cationic surfactant, cetyltrimethylammonium bromide (CTAB and an anionic surfactant, sodium dodecyl sulfate (SDS was investigated spectrophotometrically at 25.0°C. The UV spectra of the additives (acids were measured with and without surfactant above and below critical micelle concentration (cmc of the surfactant. The presence of alkyl chain in phenylalkanoic acids is responsible for hydrophobic interaction resulting in shift of the spectra towards longer wavelength (red shift. The value of partition coefficient (Kx between the bulk water and surfactant micelles and in turn standard free energy change of solubilization (ΔGpº were also estimated by measuring the differential absorbance (ΔA of the additives in micellar solutions.

Investigations of the kinetics of surfactant-assisted growth of cobalt/copper multilayers

Science.gov (United States)

Peterson, Brennan Lovelace

Surfactants---a term given to a broad family of surface additives used in thin film growth---provide a potentially useful tool for the deposition engineer. A long history of work on the field has produced a sometimes conflicting view of what surfactants do, and while their efficacy in improving magnetic films is well established, the attendant structural changes remain unclear. Early work on surfactant-assisted growth was generally confined to deposition at near equilibrium conditions: high temperature and very slow deposition rates on very smooth (single crystal) substrates. In the case of low temperature sputter deposition, the kinetic phenomena differ greatly from the near-equilibrium case: high rate, more interlayer diffusive pathways, high grain boundary density, and few well defined atomic steps. There are two major ideas which underlie and explain the use of surfactants. First, they are used to alter growth kinetics of a single material by changing the diffusion barriers on the growing surface. Second, surfactants alter the initial nucleation parameters in heteroepitaxial growth, which is often explained with reference to changes in the surface energy, gamma. Changes to these parameters result, in turn, to variations of the roughness and conformality of thin films grown with the assistance of surfactants. Finally, the roughness and conformality are critical for determining the performance of modern thin film magnetic sensors. As surfactants offer a way to alter the nucleation and growth kinetics, they offer tremendous potential benefits. However, before surfactants are trustworthy deposition tool, a better understanding of their structural effects and underlying surface energy and kinetic changes is necessary. In order to investigate these phenomena, DC magnetron sputtered [Co/Cu] multilayers were deposited on Si/SiO2 substrates using O2 , Ag, Pb, and In as surfactants. Oxygen was introduced during growth at partial pressures ranging from 10-9 to 10-6 Torr

Desorption of organophosphorous pesticides from soil with wastewater and surfactant solutions

International Nuclear Information System (INIS)

Hernandez-Soriano, M. C.; Mingorance, M. D.; Pena, A.

2009-01-01

Surfactants can be introduced in the environment by wastewater discharge, point-charge pollution or deliberate action, e. g. to remediate contaminated soil or groundwater. The irrigation of soil with wastewater containing surfactants may modify pesticide desorption from soil, thus affecting their affecting their environmental fate. Desorption from soil of the plain of Granada (South-eastern Spain) of two organophosphorous pesticides, diazinon and dimethoate, differing in solubility and hydrophobicity, has been evaluated in the presence of different surfactant aqueous solutions and municipal wastewater. (Author)

Summer/winter variability of the surfactants in aerosols from Grenoble, France

Science.gov (United States)

Baduel, Christine; Nozière, Barbara; Jaffrezo, Jean-Luc

2012-02-01

Many atmospheric aerosols seem to contain strong organic surfactants likely to enhance their cloud-forming properties. Yet, few techniques allow for the identification and characterization of these compounds. Recently, we introduced a double extraction method to isolate the surfactant fraction of atmospheric aerosol samples, and evidenced their very low surface tension (≤30 mN m -1). In this work, this analytical procedure was further optimized. In addition to an optimized extraction and a reduction of the analytical time, the improved method led to a high reproducibility in the surface tension curves obtained (shapes and minimal values), illustrated by the low uncertainties on the values, ±10% or less. The improved method was applied to PM 10 aerosols from the urban area of Grenoble, France collected from June 2009 to January 2010. Significant variability was observed between the samples. The minimum surface tension obtained from the summer samples was systematically lower (30 mN m -1) than that of the winter samples (35-45 mN m -1). Sharp transitions in the curves together with the very low surface tensions suggested that the dominating surfactants in the summer samples were biosurfactants, which would be consistent with the high biogenic activity in that season. One group of samples from the winter also displayed sharp transitions, which, together with the slightly higher surface tension, suggested the presence of weaker, possibly man-made, surfactants. A second group of curves from the winter did not display any clear transition but were similar to those of macromolecular surfactants such as polysaccharides or humic substances from wood burning. These surfactants are thus likely to originate from wood burning, the dominating source for aerosols in Grenoble in winter. These observations thus confirm the presence of surfactants from combustion processes in urban aerosols reported by other groups and illustrates the ability of our method to distinguish between

Micelle formation of nonionic surfactants in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate: surfactant chain length dependence of the critical micelle concentration.

Science.gov (United States)

Inoue, Tohru; Yamakawa, Haruka

2011-04-15

Micellization behavior was investigated for polyoxyethylene-type nonionic surfactants with varying chain length (C(n)E(m)) in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF(4)). Critical micelle concentration (cmc) was determined from the variation of (1)H NMR chemical shift with the surfactant concentration. The logarithmic value of cmc decreased linearly with the number of carbon atoms in the surfactant hydrocarbon chain, similarly to the case observed in aqueous surfactant solutions. However, the slope of the straight line is much smaller in bmimBF(4) than in aqueous solution. Thermodynamic parameters for micelle formation estimated from the temperature dependence of cmc showed that the micellization in bmimBF(4) is an entropy-driven process around room temperature. This behavior is also similar to the case in aqueous solution. However, the magnitude of the entropic contribution to the overall micellization free energy in bmimBF(4) is much smaller compared with that in aqueous solution. These results suggest that the micellization in bmimBF(4) proceeds through a mechanism similar to the hydrophobic interaction in aqueous surfactant solutions, although the solvophobic effect in bmimBF(4) is much weaker than the hydrophobic effect. Copyright © 2011 Elsevier Inc. All rights reserved.

Surfactant effect on functionalized carbon nanotube coated snowman-like particles and their electro-responsive characteristics

Energy Technology Data Exchange (ETDEWEB)

Zhang, Ke; Liu, Ying Dan [Department of Polymer Science and Engineering, Inha University, Incheon 402-751 (Korea, Republic of); Choi, Hyoung Jin, E-mail: hjchoi@inha.ac.kr [Department of Polymer Science and Engineering, Inha University, Incheon 402-751 (Korea, Republic of)

2012-10-15

The core–shell structured snowman-like (SL) microparticles coated by functionalized multi-walled carbon nanotube (MWNT) were prepared in the presence of different surfactants including cationic surfactant-cetyl trimethylammonium bromide (CTAB) and anionic surfactant-sodium lauryl sulfate (SDS). The effect of surfactants on adsorption onto SL particles was characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and conductivity. The cationic surfactant is found to be more effective than anionic surfactant for helping nanotube adsorbed onto microparticle due to the presence of electrostatic interaction between the functionalized MWNT and the surfactant. Furthermore, the MWNT/SL particles dispersed in silicone oil exhibited a typical fibril structure of the electrorheological characteristics under an applied electric field observed by an optical microscope (OM), in which the state of nanotubes wrapped on the particles strongly affects their electro-responsive characteristics.

Surfactant effect on functionalized carbon nanotube coated snowman-like particles and their electro-responsive characteristics

International Nuclear Information System (INIS)

Zhang, Ke; Liu, Ying Dan; Choi, Hyoung Jin

2012-01-01

The core–shell structured snowman-like (SL) microparticles coated by functionalized multi-walled carbon nanotube (MWNT) were prepared in the presence of different surfactants including cationic surfactant-cetyl trimethylammonium bromide (CTAB) and anionic surfactant-sodium lauryl sulfate (SDS). The effect of surfactants on adsorption onto SL particles was characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and conductivity. The cationic surfactant is found to be more effective than anionic surfactant for helping nanotube adsorbed onto microparticle due to the presence of electrostatic interaction between the functionalized MWNT and the surfactant. Furthermore, the MWNT/SL particles dispersed in silicone oil exhibited a typical fibril structure of the electrorheological characteristics under an applied electric field observed by an optical microscope (OM), in which the state of nanotubes wrapped on the particles strongly affects their electro-responsive characteristics.

Surfactant Ligand Removal and Rational Fabrication of Inorganically Connected Quantum Dots

KAUST Repository

Zhang, Haitao

2011-12-14

A novel method is reported to create inorganically connected nanocrystal (NC) assemblies for both II-VI and IV-VI semiconductors by removing surfactant ligands using (NH 4) 2S. This surface modification process differs from ligand exchange methods in that no new surfactant ligands are introduced and the post-treated NC surfaces are nearly bare. The detailed mechanism study shows that the high reactivity between (NH 4) 2S and metal-surfactant ligand complexes enables the complete removal of surfactant ligands in seconds and converts the NC metal-rich shells into metal sulfides. The post-treated NCs are connected through metal-sulfide bonding and form a larger NCs film assembly, while still maintaining quantum confinement. Such "connected but confined" NC assemblies are promising new materials for electronic and optoelectronic devices. © 2011 American Chemical Society.

Adsorption of hydrophobic organic compounds onto a hydrophobic carbonaceous geosorbent in the presence of surfactants.

Science.gov (United States)

Wang, Peng; Keller, Arturo A

2008-06-01

The adsorption of hydrophobic organic compounds (HOCs; atrazine and diuron) onto lampblack was studied in the presence of nonionic, cationic, and anionic surfactants (Triton(R) X-100), benzalkonium chloride [BC], and linear alkylbenzene sulfonate [LAS]) to determine the effect of the surfactant on HOC adsorption onto a hydrophobic carbonaceous geosorbent. Linear alkylbenzene sulfonate showed an adsorption capacity higher than that of BC but similar to that of Triton X-100, implying the charge property of a surfactant is not a useful indicator for predicting the surfactant's adsorption onto a hydrophobic medium. The results also indicated that the octanol-water partition coefficient (K(OW)) of a surfactant is not a good predictor of that surfactant's sorption onto a hydrophobic medium. Under subsaturation adsorption conditions (i.e., before sorption saturation is reached), surfactant adsorption reduced HOC adsorption to a significant extent, with the reduction in HOC adsorption increasing monotonically with the amount of surfactant adsorbed. Among the three surfactants, Triton X-100 was the most effective in reducing HOC adsorption, whereas BC and LAS showed similar effectiveness in this regard. Under the same amount of the surfactant sorbed, the reduction in atrazine adsorption was consistently greater than that for diuron because of atrazine's lower hydrophobicity. No significant difference was observed in the amount of the HOC adsorbed under different adsorption sequences. Our results showed that the presence of surfactant can significantly decrease HOC adsorption onto hydrophobic environmental media and, thus, is important in predicting HOC fate and transport in the environment.

Early CPAP versus surfactant in extremely preterm infants.

Science.gov (United States)

Finer, Neil N; Carlo, Waldemar A; Walsh, Michele C; Rich, Wade; Gantz, Marie G; Laptook, Abbot R; Yoder, Bradley A; Faix, Roger G; Das, Abhik; Poole, W Kenneth; Donovan, Edward F; Newman, Nancy S; Ambalavanan, Namasivayam; Frantz, Ivan D; Buchter, Susie; Sánchez, Pablo J; Kennedy, Kathleen A; Laroia, Nirupama; Poindexter, Brenda B; Cotten, C Michael; Van Meurs, Krisa P; Duara, Shahnaz; Narendran, Vivek; Sood, Beena G; O'Shea, T Michael; Bell, Edward F; Bhandari, Vineet; Watterberg, Kristi L; Higgins, Rosemary D

2010-05-27

There are limited data to inform the choice between early treatment with continuous positive airway pressure (CPAP) and early surfactant treatment as the initial support for extremely-low-birth-weight infants. We performed a randomized, multicenter trial, with a 2-by-2 factorial design, involving infants who were born between 24 weeks 0 days and 27 weeks 6 days of gestation. Infants were randomly assigned to intubation and surfactant treatment (within 1 hour after birth) or to CPAP treatment initiated in the delivery room, with subsequent use of a protocol-driven limited ventilation strategy. Infants were also randomly assigned to one of two target ranges of oxygen saturation. The primary outcome was death or bronchopulmonary dysplasia as defined by the requirement for supplemental oxygen at 36 weeks (with an attempt at withdrawal of supplemental oxygen in neonates who were receiving less than 30% oxygen). A total of 1316 infants were enrolled in the study. The rates of the primary outcome did not differ significantly between the CPAP group and the surfactant group (47.8% and 51.0%, respectively; relative risk with CPAP, 0.95; 95% confidence interval [CI], 0.85 to 1.05) after adjustment for gestational age, center, and familial clustering. The results were similar when bronchopulmonary dysplasia was defined according to the need for any supplemental oxygen at 36 weeks (rates of primary outcome, 48.7% and 54.1%, respectively; relative risk with CPAP, 0.91; 95% CI, 0.83 to 1.01). Infants who received CPAP treatment, as compared with infants who received surfactant treatment, less frequently required intubation or postnatal corticosteroids for bronchopulmonary dysplasia (Pneonatal outcomes did not differ significantly between the two groups. The results of this study support consideration of CPAP as an alternative to intubation and surfactant in preterm infants. (ClinicalTrials.gov number, NCT00233324.) 2010 Massachusetts Medical Society

Impact of surfactants on the target recognition of Fab-conjugated PLGA nanoparticles.

Science.gov (United States)

Kennedy, Patrick J; Perreira, Ines; Ferreira, Daniel; Nestor, Marika; Oliveira, Carla; Granja, Pedro L; Sarmento, Bruno

2018-06-01

Targeted drug delivery with nanoparticles (NPs) requires proper surface ligand presentation and availability. Surfactants are often used as stabilizers in the production of targeted NPs. Here, we evaluated the impact of surfactants on ligand functionalization and downstream molecular recognition. Our model system consisted of fluorescent poly(lactic-co-glycolic acid) (PLGA) NPs that were nanoprecipitated in one of a small panel of commonly-used surfactants followed by equivalent washes and conjugation of an engineered Fab antibody fragment. Size, polydispersity index and zeta potential were determined by dynamic light scattering and laser Doppler anemometry, and Fab presence on the NPs was assessed by enzyme-linked immunosorbent assay. Most importantly, Fab-decorated NP binding to the cell surface receptor was monitored by fluorescence-activated cell sorting. 2% polyvinyl alcohol, 1% sodium cholate, 0.5% Pluronic F127 (F127) and 2% Tween-80 were initially tested. Of the four surfactants tested, PLGA NPs in 0.5% F127 and 2% Tween-80 had the highest cell binding. These two surfactants were then retested in two different concentrations, 0.5% and 2%. The Fab-decorated PLGA NPs in 2% F127 had the highest cell binding. This study highlights the impact of common surfactants and their concentrations on the downstream targeting of ligand-decorated NPs. Similar principles should be applied in the development of future targeted nanosystems where surfactants are employed. Copyright © 2018 Elsevier B.V. All rights reserved.

Relating Structure to Efficiency in Surfactant-Free Polymer/Fullerene Nanoparticle-Based Organic Solar Cells.

Science.gov (United States)

Gärtner, Stefan; Clulow, Andrew J; Howard, Ian A; Gilbert, Elliot P; Burn, Paul L; Gentle, Ian R; Colsmann, Alexander

2017-12-13

Nanoparticle dispersions open up an ecofriendly route toward printable organic solar cells. They can be formed from a variety of organic semiconductors by using miniemulsions that employ surfactants to stabilize the nanoparticles in dispersion and to prevent aggregation. However, whenever surfactant-based nanoparticle dispersions have been used to fabricate solar cells, the reported performances remain moderate. In contrast, solar cells from nanoparticle dispersions formed by precipitation (without surfactants) can exhibit power conversion efficiencies close to those of state-of-the-art solar cells processed from blend solutions using chlorinated solvents. In this work, we use small-angle neutron scattering measurements and transient absorption spectroscopy to investigate why surfactant-free nanoparticles give rise to efficient organic solar cells. We show that surfactant-free nanoparticles comprise a uniform distribution of small semiconductor domains, similar to that of bulk-heterojunction films formed using traditional solvent processing. This observation differs from surfactant-based miniemulsion nanoparticles that typically exhibit core-shell structures. Hence, the surfactant-free nanoparticles already possess the optimum morphology for efficient energy conversion before they are assembled into the photoactive layer of a solar cell. This structural property underpins the superior performance of the solar cells containing surfactant-free nanoparticles and is an important design criterion for future nanoparticle inks.

The application of a mulch biofilm barrier for surfactant enhanced polycyclic aromatic hydrocarbon bioremediation

International Nuclear Information System (INIS)

Seo, Youngwoo; Lee, Woo-Hyung; Sorial, George; Bishop, Paul L.

2009-01-01

Lab scale mulch biofilm barriers were constructed and tested to evaluate their performance for preventing the migration of aqueous and surfactant solubilized PAHs. The spatial distribution of viable PAH degrader populations and resultant biofilm formation were also monitored to evaluate the performance of the biobarrier and the prolonged surfactant effect on the PAH degrading microorganism consortia in the biobarrier. Sorption and biodegradation of PAHs resulted in stable operation of the system for dissolved phenanthrene and pyrene during 150 days of experimentation. The nonionic surfactant could increase the solubility of phenanthrene and pyrene significantly. However, the biobarrier itself couldn't totally prevent the migration of micellar solubilized phenanthrene and pyrene. The presence of surfactant and the resultant highly increased phenanthrene or pyrene concentration didn't appear to cause toxic effects on the attached biofilm in the biobarrier. However, the presence of surfactant did change the structural composition of the biofilm. - Mulch biofilm barrier showed potential for surfactant enhanced bioremediation, and the presence of surfactant changed the structural composition of the biofilm

Surfactant induced flows in thin liquid films : an experimental study

NARCIS (Netherlands)

Sinz, D.K.N.

2012-01-01

The topic of the experimental work summarized in my thesis is the flow in thin liquid films induced by non-uniformly distributed surfactants. The flow dynamics as a consequence of the deposition of a droplet of an insoluble surfactant onto a thin liquid film covering a solid substrate where

Nonionic surfactant Brij35 effects on toluene biodegradation in a ...

African Journals Online (AJOL)

Nonionic surfactant effects on the toluene dissolved in the water phase and biodegradation kinetic behaviors of toluene in a composite bead biofilter were investigated. The toluene dissolved in the water phase was enhanced by the addition of surfactant into aqueous solution and the enhancing effect was more pronounced ...

Effects of surfactant micelles on viscosity and conductivity of poly(ethylene glycol) solutions

Science.gov (United States)

Wang, Shun-Cheng; Wei, Tzu-Chien; Chen, Wun-Bin; Tsao, Heng-Kwong

2004-03-01

The neutral polymer-micelle interaction is investigated for various surfactants by viscometry and electrical conductometry. In order to exclude the well-known necklace scenario, we consider aqueous solutions of low molecular weight poly(ethylene glycol) (2-20)×103, whose radial size is comparable to or smaller than micelles. The single-tail surfactants consist of anionic, cationic, and nonionic head groups. It is found that the viscosity of the polymer solution may be increased several times by micelles if weak attraction between a polymer segment and a surfactant exists, ɛsurfactant concentration is therefore attributed to the considerable cross links among micelles and polymers (transient network). In addition to substantial alteration of the transport properties, this weak interaction also influences the onset point of thermodynamic instability associated with polymer-surfactant solutions. The examples include the decrease of critical aggregation concentration for ionic surfactant and clouding point for nonionic surfactant due to PEG addition.

Surfactant-adsorption-induced initial depinning behavior in evaporating water and nanofluid sessile droplets.

Science.gov (United States)

Zhong, Xin; Duan, Fei

2015-05-19

A surfactant-induced autophobic effect has been observed to initiate an intense depinning behavior at the initial stage of evaporation in both pure water and nanofluid sessile droplets. The cationic surfactant adsorbing to the negatively charged silicon wafer makes the solid surface more hydrophobic. The autophobing-induced depinning behavior, leading to an enlarged contact angle and a shortened base diameter, takes place only when the surfactant concentration is below its critical micelle concentration (cmc). The initial spreading degree right before the droplet retraction, the retracting velocity of the contact line, and the duration of the initial droplet retraction are shown to depend negatively on the surfactant concentration below the cmc. An unexpected enhancement in the initial depinning has been found in the nanofluid droplets, possibly resulting from the hydrophilic interplay between the graphite nanoparticle deposition and the surfactant molecules. Such promotion of the initial depinning due to the nanoparticle deposition makes the droplet retract even at a surfactant concentration higher than the cmc (1.5 cmc). The resulting deposition formed in the presence of the depinning behavior has great enhancement for coffee-ring formation as compared to the one free of surfactant, implying that the formation of a coffee ring does not require the pinning of the contact line during the entire drying process.

Influence of pulmonary surfactant on in vitro bactericidal activities of amoxicillin, ceftazidime, and tobramycin

NARCIS (Netherlands)

A. van 't Veen (Annemarie); J.W. Mouton (Johan); D.A.M.P.J. Gommers (Diederik); J.A.J.W. Kluytmans (Jan); P. Dekkers; B.F. Lachmann (Burkhard)

1995-01-01

textabstractThe influence of a natural pulmonary surfactant on antibiotic activity was investigated to assess the possible use of exogenous surfactant as a vehicle for antibiotic delivery to the lung. The influence of surfactant on the bactericidal activity of

Improved surfactants formulation for remediation of oil sludge recovery

International Nuclear Information System (INIS)

Syed Hakimi Sakuma Syed Ahmad; Shahidan Radiman

2000-01-01

Surfactant enhanced remediation based on mobilisation of the residual NAPLs (oil sludge) which is radioactive depends on the tendency of the surfactants to lower interfacial tension. Mobilisation has greater potential than solubilisation to increase the rate of remediation. Optimised surfactants formulation was determined with concentration of Aqua 2000 and D Bond of 1% wt respectively, sodium chloride concentration of 2 gmL -1 and addition of 3% wt butanol as cosolvent. The formulation was of benefit not only able to decrease further the interfacial tension of aqueous solution containing oil emulsion, but also to make possible to be more mobile and destruction of mixed liquid crystals that formed. Formation of liquid crystals can hinders significantly recovery efficiency of aqueous solution containing oil emulsion in field remediation work. In a 100 litres soil column experiment conducted containing oil emulsion in field sludge soil and using the surfactants formulation for flushing, miniemulsion formed sizes maintained at average size between 125 nm and 280 nm before and after remediation. Total oil and grease concentration removed from the soil were significant due to the decreased in oil emulsion sizes, increase mobility and solubility. (Author)

Surfactants non-monotonically modify the onset of Faraday waves

Science.gov (United States)

Strickland, Stephen; Shearer, Michael; Daniels, Karen

2017-11-01

When a water-filled container is vertically vibrated, subharmonic Faraday waves emerge once the driving from the vibrations exceeds viscous dissipation. In the presence of an insoluble surfactant, a viscous boundary layer forms at the contaminated surface to balance the Marangoni and Boussinesq stresses. For linear gravity-capillary waves in an undriven fluid, the surfactant-induced boundary layer increases the amount of viscous dissipation. In our analysis and experiments, we consider whether similar effects occur for nonlinear Faraday (gravity-capillary) waves. Assuming a finite-depth, infinite-breadth, low-viscosity fluid, we derive an analytic expression for the onset acceleration up to second order in ɛ =√{ 1 / Re } . This expression allows us to include fluid depth and driving frequency as parameters, in addition to the Marangoni and Boussinesq numbers. For millimetric fluid depths and driving frequencies of 30 to 120 Hz, our analysis recovers prior numerical results and agrees with our measurements of NBD-PC surfactant on DI water. In both case, the onset acceleration increases non-monotonically as a function of Marangoni and Boussinesq numbers. For shallower systems, our model predicts that surfactants could decrease the onset acceleration. DMS-0968258.

Vitamin K-dependent carboxylation of pulmonary surfactant-associated proteins

International Nuclear Information System (INIS)

Rannels, S.R.; Gallaher, K.J.; Wallin, R.; Rannels, D.E.

1987-01-01

Rat type II pneumocytes expressed vitamin K-dependent carboxylase activity that incorporated 14 CO 2 into microsomal protein precursors of molecular weights similar to those of surfactant-associated proteins (SAP). Compared to carboxylated precursor proteins present in the liver, these molecules appeared to be unique to the lung. Antibodies raised against purified rat surfactant reacted with SAP resolved by NaDodSO 4 /PAGE and with surfactant-containing lamellar bodies in type II pneumocyte cytoplasm. NaDodSO 4 /PAGE of microsomal proteins, after carboxylase-catalyzed incorporation of 14 CO 2 , demonstrated radiolabeled, immunoreactive products identical to SAP. The presence of γ-carboxyglutamic acid in these proteins was confirmed by HPLC analysis of SAP hydrolysates. Furthermore, lung carboxylase activity and SAP matured over similar time courses during fetal lung development. These results show that SAP are carboxylated by type II cells via a vitamin K-dependent pathway analogous to that for hepatic carboxylation of clotting factors. Further analogy to the clotting system suggest that γ-carboxyglutamic acid residues in SAP polypeptides play a role in Ca 2+ binding and thus in the known requirements for both cation and SAP in the physiological function of pulmonary surfactant

Clearance of 99mTc-DTPA and experimentally increased alveolar surfactant content

International Nuclear Information System (INIS)

Bos, J.A.H.; Wollmer, P.; Bakker, W.; Hannappel, E.; Lachmann, B.

1992-01-01

The authors measured clearance of 99m Tc-labeled diethylenetriamine pentaacetic acid ( 99m Tc-DTPA) in rabbits with experimentally increased alveolar surfactant content. In one group of animals, surfactant production was increased by treatment with ambroxol, and another group of animals was treated with tracheal instillation of natural surfactant. A group of untreated control animals and animals treated with instillation of saline were also studied. Clearance was measured during standard conditions of mechanical ventilation and during ventilation with large tidal volumes. In ambroxol- and surfactant-treated groups, clearance rate was reduced compared with untreated control animals. In contrast, clearance rate increased after saline instillation. The differences were observed at both modes of ventilation. The findings indicate that the pulmonary surfactant system is a rate-limiting factor for the clearance of 99m Tc-DTPA and that the volume dependence of clearance is not explained by stretching of the alveolar wall only. 28 refs., 2 figs., 1 tab

Experimental Study on the Properties and Displacement Effects of Polymer Surfactant Solution

Directory of Open Access Journals (Sweden)

Ke-Liang Wang

2013-01-01

Full Text Available Based on the characteristics of oil reservoirs and the requirements of further enhancing oil recovery at high water cut stage of Pubei Oilfield, the displacement performance of polymer surfactant is evaluated. Reasonable injection parameters and oil displacement effects after water flooding are also researched. Compared with conventional polymer with intermediate molecular weight, polymer surfactant has the properties of higher viscosity at low concentration condition and lower interfacial tension. Laboratory experiments indicate that the displacement effect of polymer surfactant is much better than that of conventional polymer at a slug size of 0.57 PV. The oil recovery of polymer surfactant increases by more than 10% after water flooding. Considering the actual situation of low-permeability of Pubei Oilfield reservoirs, the system viscosity of 30 mPa·s is chosen. The corresponding concentration of Type III polymer surfactant is 600 mg/L and the injected slug is 0.57 PV and the oil recovery can be increased by 11.69%.

Stable intermediates determine proteins' primary unfolding sites in the presence of surfactants

DEFF Research Database (Denmark)

Petersen, Steen Vang; Andersen, Kell kleiner; Enghild, Jan J.

2009-01-01

Despite detailed knowledge of the overall structural changes and stoichiometries of surfactant binding, little is known about which protein regions constitute the preferred sites of attack for initial unfolding. Here we have exposed three proteins to limited proteolysis at anionic (SDS) and catio......Despite detailed knowledge of the overall structural changes and stoichiometries of surfactant binding, little is known about which protein regions constitute the preferred sites of attack for initial unfolding. Here we have exposed three proteins to limited proteolysis at anionic (SDS......) and cationic (DTAC) surfactant concentrations corresponding to specific conformational transitions, using the surfactant-robust broad-specificity proteases Savinase and Alcalase. Cleavage sites are identified by SDS-PAGE and N-terminal sequencing. We observe well-defined cleavage fragments, which suggest......, cleavage sites can be rationalized from the structure of the protein's folding transition state and the position of loops in the native state. Nevertheless, they are more sensitive to choice of surfactant and protease, probably reflecting a heterogeneous and fluctuating ensemble of partially unfolded...

Structure-activity relationship of surfactant for preparing DMFC anodic catalyst

International Nuclear Information System (INIS)

Su Yi; Xue Xinzhong; Xu Weilin; Liu Changpeng; Xing Wei; Zhou Xiaochun; Tian Tian; Lu Tianhong

2006-01-01

Three kinds of surfactants as stabilizer were applied to the preparation of electrocatalysts for direct methanol fuel cell (DMFC). The catalysts have been characterized by examining their catalytic activities, morphologies and particle sizes by means of cyclic voltammetry, chronoamperometry, X-ray diffraction and transmission electron microscopy (TEM). It is found that the surfactants with different structures have a significantly influence on the catalyst shape and activity. The catalysts prepared with non-ionic surfactants as the stabilizer show higher activity for direct oxidation of methanol. The structure-activity relationship (SAR) analysis has been explored and the effect of hydrophile-lipophile balance (HLB value) has also been discussed

Biosynthesis of Bio surfactant by Egyptian Local Bacterial Isolates Using Different Agricultural Wastes

International Nuclear Information System (INIS)

El-Shahawy, M.R.

2014-01-01

Fifteen bacterial isolates were isolated from sea water from the coast of the General Petroleum Company on Suez Gulf. They were screened for bio surfactant production using emulsification activity and haemolytic activity. The most potent isolate B11 were selected according to two parameters: The ability to grow and produce surfactant and its haemolytic activity on blood agar plates. The isolate B11 was characterized and identified as Bacillus licheniformis according to API system. The isolate was subjected to different doses of gamma irradiation in a trial to improve its ability for bio surfactant production which resulted in a passive effect on bio surfactant production. Three types of agricultural wastes (Rice straw, Cane Bagasse, Corn straw) were used as fertilizers for bio surfactant biosynthesis by the promising isolate in concentrations of 1, 2, 3, 4, 5 g/l. At five g/l concentration cane bagasse gave high production of bio surfactant with maximum capacity at (32%) flowed by rice straw at 18% and corn straw at 9.8 %.

Influence of MWCNT/surfactant dispersions on the mechanical properties of Portland cement pastes

Science.gov (United States)

Rodríguez, B.; Quintero, J. H.; Arias, Y. P.; Mendoza-Reales, O. A.; Ochoa-Botero, J. C.; Toledo-Filho, R. D.

2017-12-01

This work studies the reinforcing effect of Multi Walled Carbon Nanotubes (MWCNT) on cement pastes. A 0.35% solid concentration of MWCNT in powder was dispersed in deionized water with sodium dodecyl sulfate (cationic surfactant), cetylpyridinium chloride (anionic surfactant) and triton X-100 (amphoteric surfactant) using an ultrasonic tip processor. Three concentrations of each surfactant (1mM, 10mM and 100mM) were tested, and all samples were sonicated until an adequate dispersion degree was obtained. Cement pastes with additions of carbon nanotubes of 0.15% by mass of cement were produced in two steps; first the dispersions of MWCNT were combined with the mixing water using an ultrasonic tip processor to guarantee homogeneity, and then cement was added and mixed until a homogeneous paste was obtained. Direct tensile strength, apparent density and open porosity of the pastes were measured after 7 days of curing. It was found that the MWCNT/surfactants dispersions decrease the mechanical properties of the cement based matrix due to an increased porosity caused by the presence of surfactants.

Liquid crystalline states of surfactant solutions of isotropic micelles

International Nuclear Information System (INIS)

Bagdassarian, C.; Gelbart, W.M.; Ben-Shaul, A.

1988-01-01

We consider micellar solutions whose surfactant molecules prefer strongly to form small, globular aggregates in the absence of intermicellar interactions. At sufficiently high volume fraction of surfactant, the isotropic phase of essentially spherical micelles is shown to be unstable with respect to an orientationally ordered (nematic) state of rodlike aggregates. This behavior is relevant to the phase diagrams reported for important classes of aqueous amphiphilic solutions

Surfactant flushing remediation of o-dichlorobenzene and p-dichlorobenzene contaminated soil.

Science.gov (United States)

Pei, Guangpeng; Zhu, Yuen; Cai, Xiatong; Shi, Weiyu; Li, Hua

2017-10-01

Surfactant-enhanced remediation is used to treat dichlorobenzene (DCB) contaminated soil. In this study, soil column experiments were conducted to investigate the removal efficiencies of o-dichlorobenzene (o-DCB) and p-dichlorobenzene (p-DCB) from contaminated soil using micellar solutions of biosurfactants (saponin, alkyl polyglycoside) compare to a chemically synthetic surfactant (Tween 80). Leachate was collected and analyzed for o-DCB and p-DCB content. In addition, soil was analyzed to explore the effect of surfactants on soil enzyme activities. Results showed that the removal efficiency of o-DCB and p-DCB was highest for saponin followed by alkyl polyglycoside and Tween 80. The maximum o-DCB and p-DCB removal efficiencies of 76.34% and 80.43%, respectively, were achieved with 4 g L -1 saponin solution. However, an opposite result was observed in the cumulative mass of o-DCB and p-DCB in leachate. The cumulative extent of o-DCB and p-DCB removal by the biosurfactants saponin and alkyl polyglycoside was lower than that of the chemically synthetic surfactant Tween 80 in leachate. Soil was also analyzed to explore the effect of surfactants on soil enzyme activities. The results indicated that surfactants were potentially effective in facilitating soil enzyme activities. Thus, it was confirmed that the biosurfactants saponin and alkyl polyglycoside could be used for remediation of o-DCB and p-DCB contaminated soil. Copyright © 2017 Elsevier Ltd. All rights reserved.

Studies on interfacial tension and contact angle of synthesized surfactant and polymeric from castor oil for enhanced oil recovery

Science.gov (United States)

Babu, Keshak; Pal, Nilanjan; Bera, Achinta; Saxena, V. K.; Mandal, Ajay

2015-10-01

New synthesized polymeric surfactants have immensely attracted the researchers for further development of chemical enhanced oil recovery method particularly in surfactant flooding. Contact angle and interfacial tension measurement tests are the effective ways to identify proper chemicals/surfactants for enhanced oil recovery by chemical/surfactant flooding. In the present study a new polymeric surfactant was synthesized from pre-synthesized sodium methyl ester sulfonate (surfactant) and acrylamide for application in chemical enhanced oil recovery. The synthesized surfactant and polymeric surfactant were used to measure interfacial tension between their aqueous phase and crude oil phase to investigate the efficiency of the surfactants in reduction of interfacial tension. The synthesized polymeric surfactant has also ability to control the mobility because of its viscous nature in aqueous solution. Contact angles of solid-crude oil-surfactant interface were also measured to study the effect of the synthesized surfactant and polymeric surfactant on wettability alteration mechanism. Synergistic effect was studied by using NaCl and synthesized surfactants on interfacial tension. Dynamic interfacial tensions of the surfactant and polymeric surfactant solutions with crude oil were measured at different NaCl concentrations. Interfacial tension was found to be lowered up to 10-2 to 10-3 mN/m which is effective for oil recovery. Measurement of contact angle indicates the wettability change of the quartz surface. Comparative studies on efficiencies of synthesized sodium methyl ester sulfonate surfactant and polymeric surfactant were also carried out with respect to interfacial tension reduction and contact angle change.

Influence of clay and surfactant content in non-aqueous fluid rheology

International Nuclear Information System (INIS)

Guedes, I.C.; Gomes, N.L.; Menezes, R.R.; Campos, L.F.A.; Ferreira, H.S.

2012-01-01

The bentonite clay used as viscosity agent in the production of non-aqueous fluids cannot be used without organic treatment for their surfaces to become hydrophobic. These clays are called organophilic clays, and are generally obtained by adding, in an aqueous way, ionic or a nonionic surfactant. Recent studies of the variables involved in the dispersion of bentonite clays and in the process of organophilization, showed their lack of influence. This work aims to study the influence of clay content and surfactants on the rheology of nonaqueous fluids. To this end, the clays were treats and characterized, evidencing the incorporation of the surfactant, and then formulated non-aqueous fluids, following PETROBRAS standards, being possible to verify the influence of clay content and surfactant both from the point of view as the characterizing and rheological behavior. (author)

COUPLING THE ALKALINE-SURFACTANT-POLYMER TECHNOLOGY AND THE GELATION TECHNOLOGY TO MAXIMIZE OIL PRODUCTION

Energy Technology Data Exchange (ETDEWEB)

Malcolm Pitts; Jie Qui; Dan Wilson; Phil Dowling

2004-05-01

Gelation technologies have been developed to provide more efficient vertical sweep efficiencies for flooding naturally fractured oil reservoirs or more efficient areal sweep efficiency those with high permeability contrast ''thief zones''. The field proven alkaline-surfactant-polymer technology economically recovers 15% to 25% OOIP more oil than waterflooding in the swept pore space of an oil reservoir. However, alkaline-surfactant-polymer technology is not amenable to the naturally fractured reservoirs or those with thief zones because much of the injected solution bypasses the target pore space containing oil. The objective of this work is to investigate whether combining these two technologies could broaden the applicability of alkaline-surfactant-polymer flooding into these reservoirs. Fluid-fluid interaction with different gel chemical compositions and alkaline-surfactant-polymer solution with pH values ranging from 9.2 to 12.9 have been tested. Aluminum-polyacrylamide gels are not stable to alkaline-surfactant-polymer solutions at any pH. Chromium--polyacrylamide gels with polymer to chromium ion ratios of 25 or greater were stable to alkaline-surfactant-polymer solutions if solution pH was 10.6 or less. When the polymer to chromium ion was 15 or less, chromium-polyacrylamide gels were stable to alkaline-surfactant-polymer solutions with pH values up to 12.9. Chromium-xanthan gum gels were stable to alkaline-surfactant-polymer solutions with pH values of 12.9 at the polymer to chromium ion ratios tested. Silicate-polyacrylamide, resorcinol-formaldehyde, and sulfomethylated resorcinol-formaldehyde gels were also stable to alkaline-surfactant-polymer solutions with pH values ranging from 9.2 to 12.9. Iron-polyacrylamide gels were immediately destroyed when contacted with any of the alkaline-surfactant-polymer solutions with pH values of 9.2 to 12.9.

Modification of Deeply Buried Hydrophobic Interfaces by Ionic Surfactants

Energy Technology Data Exchange (ETDEWEB)

L Tamam; D Pontoni Z Sapir; S Yefet; S Sloutskin; B Ocko; H Reichert; M Deutsch

2011-12-31

Hydrophobicity, the spontaneous segregation of oil and water, can be modified by surfactants. The way this modification occurs is studied at the oil-water interface for a range of alkanes and two ionic surfactants. A liquid interfacial monolayer, consisting of a mixture of alkane molecules and surfactant tails, is found. Upon cooling, it freezes at T{sub s}, well above the alkane's bulk freezing temperature, T{sub b}. The monolayer's phase diagram, derived by surface tensiometry, is accounted for by a mixtures-based theory. The monolayer's structure is measured by high-energy X-ray reflectivity above and below T{sub s}. A solid-solid transition in the frozen monolayer, occurring approximately 3 C below T{sub s}, is discovered and tentatively suggested to be a rotator-to-crystal transition.

Effect of surfactants on the spectrofluorimetric properties of zearalenone

International Nuclear Information System (INIS)

Appell, Michael; Bosma, Wayne B.

2011-01-01

The chemiluminescent properties of the estrogenic mycotoxin zearalenone in the presence of aqueous micellar media were investigated using steady state fluorescence techniques. Micelles of surfactants sodium dodecyl sulfate (SDS), hexadecyltrimethylammonium bromide (CTAB), and non-ionic Triton X-100 enhanced the fluorescence intensity of zearalenone in aqueous solutions. The binding constants have been determined and indicate zearalenone has the highest affinity for Triton X-100, followed by CTAB, and then by SDS. The encapsulation of zearalenone by the micelles studied is spontaneous and exothermic. The selective microenvironments provided by organized micellar systems offer an attractive medium to modulate fluorescence detection of zearalenone. - Highlights: → Surfactants can selectively modulate the fluorescence detection of zearalenone. → Binding studies provide information on the zearalenone-surfactant interactions. → Fluorescence intensity of zearalenone is related to the micelle microenvironment.

Surfactant mediated slurry formulations for Ge CMP applications

KAUST Repository

Basim, G. Bahar

2013-01-01

In this study, slurry formulations in the presence of self-assembled surfactant structures were investigated for Ge/SiO2 CMP applications in the absence and presence of oxidizers. Both anionic (sodium dodecyl sulfate-SDS) and cationic (cetyl trimethyl ammonium bromide-C12TAB) micelles were used in the slurry formulations as a function of pH and oxidizer concentration. CMP performances of Ge and SiO2 wafers were evaluated in terms of material removal rates, selectivity and surface quality. The material removal rate responses were also assessed through AFM wear rate tests to obtain a faster response for preliminary analyses. The surfactant adsorption characteristics were studied through surface wettability responses of the Ge and SiO2 wafers through contact angle measurements. It was observed that the self-assembled surfactant structures can help obtain selectivity on the silica/germanium system at low concentrations of the oxidizer in the slurry. © 2013 Materials Research Society.

Synchrotron x-ray study of the orientational ordering D2-D1 structural phase transition of freely suspended discotic strands in triphenylene hexa-n-dodecanoate

International Nuclear Information System (INIS)

Safinya, C.R.; Liang, K.S.; Varady, W.A.; Clark, N.A.; Andersson, G.

1984-01-01

We demonstrate the feasibility of x-ray scattering studies of freely suspended strands of discotic liquid crystals (of triphenylene hexa-n-dodecanoate). We are able to grow strands, which are stable for days, of diameter >50 μm with a few single crystal domains. Unexpectedly, we find that the quasi two-dimensional structural phase transition from columnar D2 to columnar D1 corresponds to the orientational ordering of columns of molecules with the molecules tilted at finite angles to the column axis in both phases

Surfactant Sputtering: Theory of a new method of surface nanostructuring by ion beams

International Nuclear Information System (INIS)

Kree, R.; Yasseri, T.; Hartmann, A.K.

2009-01-01

We present a new Monte Carlo model and a new continuum theory of surface pattern formation due to 'surfactant sputtering', i.e. erosion by ion beam sputtering including a submonolayer coverage of additional, co-sputtered surfactant atoms. This setup, which has been realized in recent experiments in a controlled way leads to a number of interesting possibilities to modify pattern forming processing conditions. We will present three simple scenarios, which illustrate some potential applications of the method. In all three cases, simple Bradley-Harper type ripples appear in the absence of surfactant, whereas new, interesting structures emerge during surfactant sputtering.

Exogenous surfactant kinetics in infant respiratory distress syndrome : A novel method with stable isotopes

NARCIS (Netherlands)

Torresin, M; Zimmermann, LJI; Cogo, PE; Cavicchioli, P; Badon, T; Giordano, G; Zacchello, F; Sauer, PJJ; Carnielli, VP

Little is known about surfactant metabolism in newborn infants, since radioactive isotopes cannot be used in humans. We describe here a new method for studying exogenous surfactant pharmacokinetics in vivo. We measured surfactant half-life, pool size, and turnover time in eight preterm infants

[Reduction of 137caesium contamination in wild boars by supplementing offered food with ammonium-iron-hexa-cyanoferrate].

Science.gov (United States)

Morfeld, P; Reddemann, J; Schungel, P; Kienzle, E

2014-01-01

This replication study investigated whether the 137caesium (137Cs) contamination of wild boars could be relevantly reduced under field conditions by adding ammonium-iron-hexa-cyanoferrate (AFCF; Prussian blue) to the food. In 285 wild boars that had been shot in six Bavarian hunting territories during the season (November until May) between 01 November 2010 and 10 December 2011 137Cs contamination was analysed. Thirty-five animals originated from two hunting territories in which offered food had been supplemented with 1250 mg AFCF per kilogram food. The control animals showed a mean 137Cs contamination of 522 Bq/kg lean skeletal muscle meat. Direct (univariable) comparisons of the two experimental territories with the four control territories yielded a mean reduction in 137Cs contamination due to Prussian bluefeeding by -211 Bq/kg (p contamination by -380 Bq/kg due to the feeding of Prussian blue in other territories.

Some aspects of surfactant action mechanism in the organic reagents - metal ions systems

International Nuclear Information System (INIS)

Chernova, R.K.; Shtykov, S.N.; Beloliptseva, G.M.; Sukhova, L.K.; Amelin, V.G.; Kulapina, E.G.

1984-01-01

Results are reviewed of investigations into the interaction of ions of Mo(6), W, Zr, Be, Sc, Nb, Ta, J, rare earths, a. o. with organic reagents of triphenylmethane class in the 8M H 2 SO 4 -pH14 acidity range and the 1x10 -3 -5x10 -6 M concentration range both in the presence and absence of different surfactant type (cetylpyridine, methyltrimethylammonium, synthanols, etc). Three types of effects, determining enhancement of the sensitivity and selectivity of reactions jn the Me-R-surfactant systems, were determined: an increase in the number of coordinated ligands, the activating effect of cation surfactants resulting in a potential complexing in acid media, multicenter interaction of polydentate ligands both via chelating groups and auxochrome groups in the presence of cation surfactants. Protolytic and flotation properties of ionic associates are considered. The observed effects are explained from the viewpoint of electrostatic and hydrophobic interactions in the R-surfactant systems, observed by the methods of NMR, polarography amperometry, conductometry. A possible use of the investigated M-R-surfactant systems as complexonometric indicators was evaluated. A possibility was shown of using them for direct titrimetric determination of hundredth milligram portions of Cu, Ga, In and Sc at a titrant concentratjon of less than 0.01 M. It follows from the estimation of basic optical parameters of the Me-R-surfactant systems that detection

Action of Monomeric/Gemini Surfactants on Free Cells and Biofilm of Asaia lannensis

Directory of Open Access Journals (Sweden)

Anna Koziróg

2017-11-01

Full Text Available We investigated the biological activity of surfactants based on quaternary ammonium compounds: gemini surfactant hexamethylene-1,6-bis-(N,N-dimethyl-N-dodecylammonium bromide (C6, synthesized by the reaction of N,N-dimethyl-N-dodecylamine with 1,6-dibromohexane, and its monomeric analogue dodecyltrimethylammonium bromide (DTAB. The experiments were performed with bacteria Asaia lannensis, a common spoilage in the beverage industry. The minimal inhibitory concentration (MIC values were determined using the tube standard two-fold dilution method. The growth and adhesive properties of bacterial cells were studied in different culture media, and the cell viability was evaluated using plate count method. Both of the surfactants were effective against the bacterial strain, but the MIC of gemini compound was significantly lower. Both C6 and DTAB exhibited anti-adhesive abilities. Treatment with surfactants at or below MIC value decreased the number of bacterial cells that were able to form biofilm, however, the gemini surfactant was more effective. The used surfactants were also found to be able to eradicate mature biofilms. After 4 h of treatment with C6 surfactant at concentration 10 MIC, the number of bacterial cells was reduced by 91.8%. The results of this study suggest that the antibacterial activity of the gemini compound could make it an effective microbiocide against the spoilage bacteria Asaia sp. in both planktonic and biofilm stages.

Action of Monomeric/Gemini Surfactants on Free Cells and Biofilm of Asaia lannensis.

Science.gov (United States)

Koziróg, Anna; Kręgiel, Dorota; Brycki, Bogumił

2017-11-22

We investigated the biological activity of surfactants based on quaternary ammonium compounds: gemini surfactant hexamethylene-1,6-bis-( N,N -dimethyl- N -dodecylammonium bromide) (C6), synthesized by the reaction of N,N -dimethyl- N- dodecylamine with 1,6-dibromohexane, and its monomeric analogue dodecyltrimethylammonium bromide (DTAB). The experiments were performed with bacteria Asaia lannensis , a common spoilage in the beverage industry. The minimal inhibitory concentration (MIC) values were determined using the tube standard two-fold dilution method. The growth and adhesive properties of bacterial cells were studied in different culture media, and the cell viability was evaluated using plate count method. Both of the surfactants were effective against the bacterial strain, but the MIC of gemini compound was significantly lower. Both C6 and DTAB exhibited anti-adhesive abilities. Treatment with surfactants at or below MIC value decreased the number of bacterial cells that were able to form biofilm, however, the gemini surfactant was more effective. The used surfactants were also found to be able to eradicate mature biofilms. After 4 h of treatment with C6 surfactant at concentration 10 MIC, the number of bacterial cells was reduced by 91.8%. The results of this study suggest that the antibacterial activity of the gemini compound could make it an effective microbiocide against the spoilage bacteria Asaia sp. in both planktonic and biofilm stages.

Surfactant proteins gene variants in premature newborn infants with severe respiratory distress syndrome.

Science.gov (United States)

Somaschini, Marco; Presi, Silvia; Ferrari, Maurizio; Vergani, Barbara; Carrera, Paola

2017-12-19

Genetic surfactant dysfunction causes respiratory failure in term and near-term newborn infants, but little is known of such condition in prematures. We evaluated genetic surfactant dysfunction in premature newborn infants with severe RDS. A total of 68 preterm newborn infants with gestational age ≤32 weeks affected by unusually severe RDS were analysed for mutations in SFTPB, SFTPC and ABCA3. Therapies included oxygen supplementation, nasal CPAP, different modalities of ventilatory support, administration of exogenous surfactant, inhaled nitric oxide and steroids. Molecular analyses were performed on genomic DNA extracted from peripheral blood and Sanger sequencing of whole gene coding regions and intron junctions. In one case histology and electron microscopy on lung tissue was performed. Heterozygous previously described rare or novel variants in surfactant proteins genes ABCA3, SFTPB and SFTPC were identified in 24 newborn infants. In total, 11 infants died at age of 2 to 6 months. Ultrastructural analysis of lung tissue of one infant showed features suggesting ABCA3 dysfunction. Rare or novel genetic variants in genes encoding surfactant proteins were identified in a large proportion (35%) of premature newborn infants with particularly severe RDS. We speculate that interaction of developmental immaturity of surfactant production in association with abnormalities of surfactant metabolism of genetic origin may have a synergic worsening phenotypic effect.

Switching wormlike micelles of selenium-containing surfactant using redox reaction.

Science.gov (United States)

Zhang, Yongmin; Kong, Weiwei; Wang, Cheng; An, Pengyun; Fang, Yun; Feng, Yujun; Qin, Zhirong; Liu, Xuefeng

2015-10-14

A novel redox-switchable wormlike micellar system was developed based on a mixture of selenium-containing zwitterionic surfactant and commercially available anionic surfactant sodium dodecyl sulfate, which reversibly and quickly responds to H2O2 and vitamin C, and shows circulatory gel/sol transition, reflecting changes in aggregate morphology from entangled worms to vesicles.

Synthesis and characterization of zeolite material from coal ashes modified by surfactant

International Nuclear Information System (INIS)

Fungaro, D.A.; Borrely, S.I.

2010-01-01

Coal ash was used as starting material for zeolite synthesis by means of hydrothermal treatment. The surfactant-modified zeolite (SMZ) was prepared by adsorbing the cationic surfactant hexadecyltrimethylammonium bromide (HDTMA-Br) on the external surface of the zeolite from coal ash. The zeolite structure stability was monitored during the characterization of the materials by FTIR, XDR and SEM. The structural parameters of surfactant-modified zeolite are very close to that of corresponding non-modified zeolite which indicates that the crystalline nature of the zeolite remained intact after required chemical treatment with HDTMA-Br molecules and heating treatment for drying. The most intense peaks in the FTIR spectrum of HDTMA-Br were observed in SMZ spectrum confirming adsorption of surfactant on zeolites. (author)

Effect of Dialkyl Ammonium Cationic Surfactants on the Microfluidity of Membranes Containing Raft Domains.

Science.gov (United States)

Uyama, Makoto; Inoue, Kaori; Kinoshita, Koichi; Miyahara, Reiji; Yokoyama, Hirokazu; Nakano, Minoru

2018-01-01

It has been reported that a lot of receptors localize in lipid raft domains and that the microfluidity of these domains regulates the activation of these receptors. In this study, we focused on the lipid raft and in order to evaluate the physicochemical effects of surfactants on microfluidity of lipid membranes, we used liposomes comprising of egg-yolk L-α-phosphatidylcholine, egg-yolk sphingomyelin, and cholesterol as a model of cell membranes containing raft domains. The microfluidity of the domains was characterized by fluorescence spectrometry using 1,6-diphenyl-1,3,5-hexatriene and 2-dimethylamino-6-lauroylnaphthalene. Among several surfactants, dialkylammonium-type cationic surfactants most efficiently increased the microfluidity. It is therefore concluded that (1) the electrostatic interaction between the cationic surfactant and eggPC/eggSM/cholesterol liposome could be important, (2) surfactants with alkyl chains more effectively inserted into membranes than those with acyl chains, and (3) cationic surfactants with lower T m values have a greater ability to increase the fluidity.

Coupling surfactants with permanganate for DNAPL removal : coinjection or sequential application as delivery methods

Energy Technology Data Exchange (ETDEWEB)

Dugan, P.J. [Carus Corp., Peru, IL (United States); Siegrist, R.L. [Colorado School of Mines, Golden, CO (United States); Crimi, M.L. [Clarkson Univ., Potsdam, NY (United States)

2010-07-01

This PowerPoint presentation described a study conducted to test the effectiveness of surfactant-enhanced permanganate for the remediation of dense nonaqueous phase liquids (DNAPL). When DNAPL enters the environment, it can pollute millions of gallons of ground water and create huge dissolved plumes that act as long-term sources of contamination. Surfactants were used to enhance the solubilization and mobilization of DNAPL during the remediation process. In situ chemical oxidation (ISCO) was then used to deliver oxidants into the sub-surface to destroy organic contaminants in the soil and ground water. Experimental 2-D flow-through cell studies of 72 surfactants were conducted with the permanganate to evaluate delivery methods and determine compatible co-solvents for the surfactant process. Delivery methods included co-injection and sequential application. Four compatible surfactants were found to be compatible with the permanganate. A 90 percent DNAPL remediation rate was achieved using relatively low surfactant and oxidant concentrations. tabs., figs.

Mass spectrometry compatible surfactant for optimized in-gel protein digestion.

Science.gov (United States)

Saveliev, Sergei V; Woodroofe, Carolyn C; Sabat, Grzegorz; Adams, Christopher M; Klaubert, Dieter; Wood, Keith; Urh, Marjeta

2013-01-15

Identification of proteins resolved by SDS-PAGE depends on robust in-gel protein digestion and efficient peptide extraction, requirements that are often difficult to achieve. A lengthy and laborious procedure is an additional challenge of protein identification in gel. We show here that with the use of the mass spectrometry compatible surfactant sodium 3-((1-(furan-2-yl)undecyloxy)carbonylamino)propane-1-sulfonate, the challenges of in-gel protein digestion are effectively addressed. Peptide quantitation based on stable isotope labeling showed that the surfactant induced 1.5-2 fold increase in peptide recovery. Consequently, protein sequence coverage was increased by 20-30%, on average, and the number of identified proteins saw a substantial boost. The surfactant also accelerated the digestion process. Maximal in-gel digestion was achieved in as little as one hour, depending on incubation temperature, and peptides were readily recovered from gel eliminating the need for postdigestion extraction. This study shows that the surfactant provides an efficient means of improving protein identification in gel and streamlining the in-gel digestion procedure requiring no extra handling steps or special equipment.

Surfactant-enhanced alkaline flooding for light oil recovery. Final report

Energy Technology Data Exchange (ETDEWEB)

Wasan, D.T.

1996-05-01

In this report, we present the results of our experimental and theoretical studies in surfactant-enhanced alkaline flooding for light oil recovery. The overall objective of this work is to develop a very cost-effective method for formulating a successful surfactant-enhanced alkaline flood by appropriately choosing mixed alkalis which form inexpensive buffers to obtain the desired pH (between 8.5 and 12. 0) for ultimate spontaneous emulsification and ultralow interfacial tension. In addition, we have (1) developed a theoretical interfacial activity model for determining equilibrium interfacial tension, (2) investigated the mechanisms for spontaneous emulsification, (3) developed a technique to monitor low water content in oil and (4) developed a technique to study water-in-oil emulsion film properties, (5) investigated the effect of surfactant on the equilibrium and transient interfacial tension, (6) investigated the kinetics of oil removal from a silica surface, and (7) developed a theoretical interfacial activity model for determining equilibrium interfacial tension, accounting for added surfactant. The results of the studies conducted during the course of this project are discussed.

Expression of the benign HEXA mutations, Arg247Trp and Arg249Trp, associated with beta-hexosaminidase A pseudodeficiency

Energy Technology Data Exchange (ETDEWEB)

Cao, Z.; Petroulakis, E.; Salo, T. [Univ. of Manitoba (Canada)] [and others

1994-09-01

{beta}-Hexosaminidase (Hex A) is a heterodimer of {alpha} and {beta} subunits encoded by the HEXA and HEXB genes, respectively. Mutations in the HEXA gene typically cause Tay-Sachs disease or less severe forms of G{sub M2} gangliosidosis. However, two benign mutations (Arg247Trp and Arg249Trp) in the {alpha}-subunit of Hex A account for Hex A deficiency in {approximately}36% of non-Jewish enzyme-defined Tay-Sachs disease carriers. These mutations do not result in any apparent clinical phenotype in individuals who are genetic compounds with a second disease-causing mutation. We expressed the {alpha}-subunit harboring each of the benign mutations separately to study activity toward the synthetic substrate, 4-MUGS, for comparison to activity from enzymes containing mutations associated with other forms of G{sub M2} gangliosidosis. The C739T (Arg247Trp;benign), C745T (Arg 249Trp; benign), G805A (Gly269Ser; adult-onset), G749A (Gly250Asp; juvenile), and C508T (Arg170Trp; infantile) mutations were introduced into the {alpha}-subunit cDNA. These were transfected alone, or with the {beta}-subunit cDNA, to generate Hex S ({alpha}{alpha}) or Hex A ({alpha}{beta}), respectively. The activities were monitored using 4-MUGS, and the levels of {alpha}-subunit protein were assessed by Western blotting. Repeated experiments show that the benign mutations produce approximately 35% of normal Hex S and 40% of normal Hex A activity. This level is much higher than that of Hex A harbouring the Gly169Ser adult-onset mutation (12%). A sequential decrease in expressed Hex A activity is observed as mutations associated with more severe phenotypes are expressed. The benign mutations also result in lower levels of mature {alpha}-subunit protein compared to normal, and slightly reduced levels of {alpha}-subunit precursor protein. The Hex A deficiency resulting from benign mutations is not as great as that associated with disease-causing mutations.

The corrosion inhibition of pure zinc in NH{sub 4}Cl aqueous solutions by N-Alkyl quaternary ammonium bromides

Energy Technology Data Exchange (ETDEWEB)

Branzoi, V.; Pilan, Luisa; Pruna, Alina [University ' Politehnica' of Bucharest, Faculty of Industrial Chemistry, Department of Physical Chemistry and Electrochemistry, Calea Grivitei, 132, Bucharest (Romania); Branzoi, Florina [Institute of Physical Chemistry Bucharest, Splaiul Independentei, 202, Bucharest (Romania)

2004-07-01

The corrosion of zinc in NH{sub 4}Cl solutions of different concentrations has been studied by potentiostatic and potentiodynamic methods and by impedance measurements. The results obtained in a potential region near the zinc corrosion potential showed that the cathodic reaction of hydrogen discharge does not fit a simple exponential law because the Tafel coefficient appears to be electrode potential dependent. At low overvoltages, in the anodic region, the corrosion process is under activation control, while at high overvoltages the process is under diffusion control. N-dodecyl, n-tetra-decyl and n-hexa-decyl ammonium bromides were used as organic inhibitors. The potentiostatic and potentiodynamic polarization studies and EIS measurements showed that each quaternary ammonium salt inhibits the corrosion of pure zinc in 1M NH{sub 4}Cl at 30 deg. C. The inhibition efficiency of the cations was discussed on the basis of Coulomb adsorption behaviour, using molecular coverage areas and polar substituent constant. The inhibition efficiency obtained from the corrosion currents was found to increase linearly with an increase in the molecular coverage area (A) for the series of tetra-alkyl ammonium ions. The efficiency of the cations increased with an increase in the positive charge of the nitrogen atom, which was due to the inductive effect of the electron-attractive groups. This effect on the Coulomb adsorption of the cations was, however, far less than that of the electron donating groups on the chemisorption of un-protonated amines. The steric requirements for the adsorption of the quaternaries with branched alkyl chains were small. Each organic compound exhibits Langmuir behaviour and inhibition increases with increasing alkyl chain length. This is attributed to cohesive Van der Waals forces between the positive head groups co-adsorbed with bromide ions on the positively charged zinc surface. (authors)

REMEDIATION OF SOILS CONTAMINATED WITH MOTOR OIL BY HIGHLY BIODEGRADABLE SURFACTANTS

Directory of Open Access Journals (Sweden)

Ignacio Moya-Ramírez

2014-06-01

Full Text Available The remediation of a sandy soil contaminated with motor oil was studied by applying two different washing procedures: one discontinuous and the other continuous. In addition the capacity of three highly biodegradable surfactants, two synthetic (Glucopon 600 and Findet 1214N/23 and a biosurfactant from Bacillus subtilis, to enhance oil removal was tested. The results obtained with the continuous procedure were much better than those achieved with the discontinuous one, even in experiments conducted with distilled water. Both the addition of surfactants and the rise in temperature significantly increased the removal of the pollutant in experiments conducted with the discontinuous procedure, but the biosurfactant showed a higher capacity for soil remediation than the synthetic surfactants at concentrations close to its CMC. Conversely, when the continuous method was used, surfactant concentration seems to have a lower effect on motor oil removal, at least below the CMC.

Fabrication of the tricontinuous mesoporous IBN-9 structure with surfactant CTAB

KAUST Repository

Zhao, Yunfeng

2011-12-13

IBN-9 is the first tricontinuous mesoporous material, consisting of three identical interpenetrating channels that are separated by a single continuous silica wall. It was originally synthesized using a specially designed surfactant as template. The need of special surfactant in the synthesis inhibits extensive investigation of this novel structure and its applications. We demonstrate in this study that such a complicated tricontinuous mesostructure can also be fabricated from the most common and commercially available surfactant cetyltrimethylammonium bromide (CTAB) with the help of polar organic additives, e.g., n-butanol. The role of n-butanol is to finely tune the surface curvature of the organic/inorganic interface during the cooperative self-assembly process. Electron microscopic techniques are employed to identify different mesostructures from the mixture. This study reveals the possibility of discovering unprecedented mesostructures from conventional surfactant-water- silicates systems. © 2011 American Chemical Society.

The Effect Of Organic Surfactants On The Properties Of Common Hygroscopic Particles: Effective Densities, Reactivity And Water Evaporation Of Surfactant Coated Particles

Science.gov (United States)

Cuadrarodriguez, L.; Zelenyuk, A.; Imre, D.; Ellison, B.

2006-12-01

Measurements of atmospheric aerosol compositions routinely show that organic compounds account for a very large fraction of the particle mass. The organic compounds that make up this aerosol mass represent a wide range of molecules with a variety of properties. Many of the particles are composed of hygroscopic salts like sulfates, nitrates and sea-salt internally mixed with organics. While the properties of the hygroscopic salts are known, the effect of the organic compounds on the microphysical and chemical properties which include CCN activity is not clear. .One particularly interesting class of internally mixed particles is composed of aqueous salts solutions that are coated with organic surfactants which are molecules with long aliphatic chain and a water soluble end. Because these molecules tend to coat the particles' surfaces, a monolayer might be sufficient to drastically alter their hygroscopic properties, their CCN activity, and reactivity. The aliphatic chains, being exposed to the oxidizing atmosphere are expected to be transformed through heterogeneous chemistry, yielding complex products with mixed properties. We will report the results from a series of observations on ammonium sulfate, sodium chloride and sea salt particles coated with three types of surfactant molecules: sodium lauryl sulfate, sodium oleate and laurtrimonium chloride. We have been able to measure the effective densities of internally mixed particles with a range of surfactant concentration that start below a monolayer and extend all the way to particles composed of pure surfactant. For many of the measurements the data reveal a rather complex picture that cannot be simply interpreted in terms of the known pure-compound densities. For unsaturated hydrocarbons we observed and quantified the effect of oxidation by ozone on particle size, effective density and individual particle mass spectral signatures. One of the more important properties of these surfactants is that they can form a

Degradation of Surfactants in Hydroponic Wheat Root Zones

Science.gov (United States)

Monje, Oscar; McCoy, Lashelle; Flanagan, Aisling

Hygiene water recycling in recirculating hydroponic systems can be enhanced by plant roots by providing a substrate and root exudates for bacterial growth. However, reduced plant growth can occur during batch mode additions of high concentrations of surfactant. An analog hygiene water stream containing surfactants (Steol CS330, Mirataine CB) was added to a hydroponically-grown wheat plant root zone. The plants were grown at 700 mol mol-1 CO2, a photosynthetic photon flux of 300 mol m-2 s-1, and a planting density of 380 plants m-2. Volumetric oxygen mass transfer coefficients were determined using the fermentative/dynamic outgassing method to maintain adequate oxygen mass transfer rates in the root zone. This analysis suggested an optimal flow rate of the hydroponic solution of 5 L min-1. The hydroponic system was inoculated with biofilm from a bioreactor and rates of surfactant degradation were measured daily based on reduction in chemical oxygen demand (COD). The COD decreased from 400 to 100 mg L-1 after 2 days following batch addition of the analog hygiene water to the hydroponic system. Measurements of dissolved oxygen concentration and solution temperature suggest that the root zone was provided adequate aeration to meet both oxygen demands from plant and microbial respiration during the degradation of the surfactant. Results from this study show that hydroponic systems can be used to enhance rates of hygiene water processing.

Biomimetic oligosaccharide and peptide surfactant polymers designed for cardiovascular biomaterials

Science.gov (United States)

Ruegsegger, Mark Andrew

A common problem associated with cardiovascular devices is surface induced thrombosis initiated by the rapid, non-specific adsorption of plasma proteins onto the biomaterial surface. Control of the initial protein adsorption is crucial to achieve the desired longevity of the implanted biomaterial. The cell membrane glycocalyx acts as a non-thrombogenic interface through passive (dense oligosaccharide structures) and active (ligand/receptor interactions) mechanisms. This thesis is designed to investigate biomimicry of the cell glycocalyx to minimize non-specific protein adsorption and promote specific ligand/receptor interactions. Biomimetic macromolecules were designed through the molecular-scale engineering of polymer surfactants, utilizing a poly(vinyl amine) (PVAm) backbone to which hydrophilic (dextran, maltose, peptide) and hydrophobic alkyl (hexanoyl or hexanal) chains are simultaneously attached. The structure was controlled through the molar feed ratio of hydrophobic-to-hydrophilic groups, which also provided control of the solution and surface-active properties. To mimic passive properties, a series of oligomaltose surfactants were synthesized with increasing saccharide length (n = 2, 7, 15 where n is number of glucose units) to investigate the effect of coating height on protein adsorption. The surfactants were characterized by infra red (IR) and nuclear magnetic resonance (NMR) spectroscopies for structural properties and atomic force microscopy (AFM) and contact angle goniometry for surface activity. Protein adsorption under dynamic flow (5 dyn/cm2) was reduced by 85%--95% over the bare hydrophobic substrate; platelet adhesion dropped by ˜80% compared to glass. Peptide ligands were incorporated into the oligosaccharide surfactant to promote functional activity of the passive coating. The surfactants were synthesized to contain 0%, 25%, 50%, 75%, and 100% peptide ligand density and were stable on hydrophobic surfaces. The peptide surface density was

Naturally occurring surfactants and their functional design. Seitai yurai safakutanto to kinoka sekkei

Energy Technology Data Exchange (ETDEWEB)

Ishigami, Y [National Inst. of Materials and Chemical Research, Tsukuba (Japan)

1994-04-20

An active use of the natural materials replaced the petroleum chemical products and an attempt for a development of the organism imitation materials are not limited only on the surfactants, but become a great trend also widely over the dyestuff, plastics material, food, cosmetics, agricultural chemicals and so forth. In addition, an institution of the recognition system for an 'eco-mark' is done, and a development of the environment conformity materials (eco-material) is advanced. In Japan since around 1950, a practical application and a research and development of new surfactants have been rapidly progressed making the derivatives originated in a petroleum chemistry as an axis. In this paper, including a viewpoint of the ecotechnology, a chemical structure and function of the surfactant being derived from the organisms, a molecule design and attempt for functional material making of the biomimetic surfactants are described. The author considers the biomimetic surfactants as one of the approaches to develop a new functional surfactant as the new raw materials, and is performing a development of the admixtures for improving a defect the soap has and so forth. 80 refs., 3 figs., 5 tabs.

Surfactant-aided size exclusion chromatography

NARCIS (Netherlands)

Horneman, D.A.; Wolbers, M.; Zomerdijk, M.; Ottens, M.; Keurentjes, J.T.F.; Wielen, van der L.A.M.

2004-01-01

The flexibility and selectivity of size exclusion chromatog. (SEC) for protein purifn. can be modified by adding non-ionic micelle-forming surfactants to the mobile phase. The micelles exclude proteins from a liq. phase similar to the exclusion effect of the polymer fibers of the size exclusion

A PIV Study of Drop-interface Coalescence with Surfactants

Science.gov (United States)

Weheliye, Weheliye Hashi; Dong, Teng; Angeli, Panagiota

2017-11-01

In this work, the coalescence of a drop with an aqueous-organic interface was studied by Particle Image Velocimetry (PIV). The effect of surfactants on the drop surface evolution, the vorticity field and the kinetic energy distribution in the drop during coalescence were investigated. The coalescence took place in an acrylic rectangular box with 79% glycerol solution at the bottom and Exxsol D80 oil above. The glycerol solution drop was generated through a nozzle fixed at 2cm above the aqueous/oil interface and was seeded with Rhodamine particles. The whole process was captured by a high-speed camera. Different mass ratios of non-ionic surfactant Span80 to oil were studied. The increase of surfactant concentration promoted deformation of the interface before the rupture of the trapped oil film. At the early stages after film rupture, two counter-rotating vortices appeared at the bottom of the drop which then travelled to the upper part. The propagation rates, as well as the intensities of the vortices decreased at high surfactant concentrations. At early stages, the kinetic energy was mainly distributed near the bottom part of the droplet, while at later stages it was distributed near the upper part of the droplet. Programme Grant MEMPHIS, Chinese Scholarship Council (CSC).

Interactions of structurally modified surfactants with reservoir minerals: Calorimetric, spectroscopic and electrokinetic study

Energy Technology Data Exchange (ETDEWEB)

Somasundaran, P.; Sivakumar, A.; Xu, Q.

1991-03-01

The objective of this project is to elucidate mechanisms of adsorption of structurally modified surfactants on reservoir minerals and to develop a full understanding of the effect of the surfactant structure on the nature of the adsorbed layers at the molecular level. An additional aim is to study the adsorption of surfactant mixtures on simple well-characterized minerals and on complex minerals representing real conditions. The practical goal of these studies is the identification of the optimum surfactant structures and their combinations for micellar flooding. In this work, the experiments on adsorption were focussed on the position of sulfonate and methyl groups on the aromatic ring of alkyl xylene sulfonates. A multi-pronged approach consisting of calorimetry, electrokinetics, wettability and spectroscopy is planned to elucidate the adsorption mechanism of surfactants and their mixtures on minerals such as alumina and kaolinite. 32 refs., 15 figs., 7 tabs.

Interfacial rheological properties of adsorbed protein layers and surfactants : a review

NARCIS (Netherlands)

Bos, M.A.; Vliet, T. van

2001-01-01

Proteins and low molecular weight (LMW) surfactants are widely used for the physical stabilisation of many emulsions and foam based food products. The formation and stabilisation of these emulsions and foams depend strongly on the interfacial properties of the proteins and the LMW surfactants.

Vacuolar ATPase regulates surfactant secretion in rat alveolar type II cells by modulating lamellar body calcium.

Directory of Open Access Journals (Sweden)

Narendranath Reddy Chintagari

2010-02-01

Full Text Available Lung surfactant reduces surface tension and maintains the stability of alveoli. How surfactant is released from alveolar epithelial type II cells is not fully understood. Vacuolar ATPase (V-ATPase is the enzyme responsible for pumping H(+ into lamellar bodies and is required for the processing of surfactant proteins and the packaging of surfactant lipids. However, its role in lung surfactant secretion is unknown. Proteomic analysis revealed that vacuolar ATPase (V-ATPase dominated the alveolar type II cell lipid raft proteome. Western blotting confirmed the association of V-ATPase a1 and B1/2 subunits with lipid rafts and their enrichment in lamellar bodies. The dissipation of lamellar body pH gradient by Bafilomycin A1 (Baf A1, an inhibitor of V-ATPase, increased surfactant secretion. Baf A1-stimulated secretion was blocked by the intracellular Ca(2+ chelator, BAPTA-AM, the protein kinase C (PKC inhibitor, staurosporine, and the Ca(2+/calmodulin-dependent protein kinase II (CaMKII, KN-62. Baf A1 induced Ca(2+ release from isolated lamellar bodies. Thapsigargin reduced the Baf A1-induced secretion, indicating cross-talk between lamellar body and endoplasmic reticulum Ca(2+ pools. Stimulation of type II cells with surfactant secretagogues dissipated the pH gradient across lamellar bodies and disassembled the V-ATPase complex, indicating the physiological relevance of the V-ATPase-mediated surfactant secretion. Finally, silencing of V-ATPase a1 and B2 subunits decreased stimulated surfactant secretion, indicating that these subunits were crucial for surfactant secretion. We conclude that V-ATPase regulates surfactant secretion via an increased Ca(2+ mobilization from lamellar bodies and endoplasmic reticulum, and the activation of PKC and CaMKII. Our finding revealed a previously unrealized role of V-ATPase in surfactant secretion.

Nanofiltration: ion exchange system for effective surfactant removal from water solutions

Directory of Open Access Journals (Sweden)

I. Kowalska

2014-12-01

Full Text Available A system combining nanofiltration and ion exchange for highly effective separation of anionic surfactant from water solutions was proposed. The subjects of the study were nanofiltration polyethersulfone membranes and ion-exchange resins differing in type and structure. The quality of the treated solution was affected by numerous parameters, such as quality of the feed solution, membrane cut-off, resin type, dose and the solution contact time with the resin. A properly designed purification system made it possible to reduce the concentration of anionic surfactant below 1 mg L-1 from feed solutions containing surfactant in concentrations above the CMC value.

Derecruitment Test and Surfactant Therapy in Patients with Acute Lung Injury

Directory of Open Access Journals (Sweden)

Alexey A. Smetkin

2012-01-01

Full Text Available Introduction. A recruitment maneuver (RM may improve gas exchange in acute lung injury (ALI. The aim of our study was to assess the predictive value of a derecruitment test in relation to RM and to evaluate the efficacy of RM combined with surfactant instillation in patients with ALI. Materials and Methods. Thirteen adult mechanically ventilated patients with ALI were enrolled into a prospective pilot study. The patients received protective ventilation and underwent RM followed by a derecruitment test. After a repeat RM, bovine surfactant (surfactant group, n=6 or vehicle only (conventional therapy group, n=7 was instilled endobronchially. We registered respiratory and hemodynamic parameters, including extravascular lung water index (EVLWI. Results. The derecruitment test decreased the oxygenation in 62% of the patients. We found no significant correlation between the responses to the RM and to the derecruitment tests. The baseline EVLWI correlated with changes in SpO2 following the derecruitment test. The surfactant did not affect gas exchange and lung mechanics but increased EVLWI at 24 and 32 hrs. Conclusions. Our study demonstrated no predictive value of the derecruitment test regarding the effects of RM. Surfactant instillation was not superior to conventional therapy and might even promote pulmonary edema in ALI.

BINDING OF IONIC SURFACTANTS ON OPPOSITELY CHARGED POLYELECTROLYTES OBSERVED BY FLUORESCENCE METHODS

Institute of Scientific and Technical Information of China (English)

Zhen Tong; Chao-yang Wang; Bi-ye Ren; Xin-xing Liu; Fang Zeng

2003-01-01

Our recent studies concerning the binding of ionic surfactants on oppositely charged polyelectrolytes observed with fluorescence techniques are reviewed. The cationic surfactants cetyltrimethylammonium bromide (CTAB),dodecyltrimethylammonium chloride (DTAC), and nonionic surfactant octaethylene glycol monododecyl ether (C12E8) were allowed to bind on anionic poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) and its pyrene and/or naphthalene labeled copolymers. The relative excimer emission intensity IE/IM of a cationic probe 1-pyrenemethylamine hydrochloride were chosen to monitor the binding process and the conformation change of surfactant-bound polyelectrolytes. The 1:1aggregation of polyelectrolyte-CTAB with respect to the charge was found as long as the CTAB concentration was slightly higher than its critical aggregation concentration (CAC). The intermolecular NRET indicated that the CTAB-bound polyelectrolytes aggregated together through the hydrophobic interaction between the CTAB tails. However, neither 1:1polyelectrolyte-DTAC aggregation nor intermolecular aggregation of DTAC-bound polyelectrolyte was observed owing to its weaker hydrophobicity of 12 carbon atoms in the tail, which is shorter than that of CTAB. As known from the fluorescence results, nonionic surfactant C12E8 did not bind on the anionic polyelectrolytes, but the presence of PAMPS promoted the micelle formation for C12E8 at the CAC slightly below its critical micelle concentration (CMC). The solid complex of dansyl labeled AMPS copolymer-surfactant exhibited a decrease in local polarity with increasing charge density of the polyelectrolyte or with alkane tail length of the surfactant. SAXS suggested a lamella structure for the AMPS copolymersurfactant solid complexes with a long period of 3.87 nm for CTAB and 3.04 nm for DTAC, respectively.

Modification of shape oscillations of an attached bubble by surfactants

Directory of Open Access Journals (Sweden)

Tihon J.

2013-04-01

Full Text Available Surface-active agents (surfactants, e.g. washing agents strongly modifies properties of gas-liquid interface. We have carried out extensive experiments, in which we study effect of surfactants on the shape oscillations of a bubble, which is attached at a tip of a capillary. In the experiments, shape oscillations of a bubble are invoked by a motion of a capillary, to which the bubble is injected. Decaying oscillations are recorded and their frequency and damping are evaluated. By changing the excitation frequency, three lowest oscillation modes are studied. Experiments were repeated in aqueous solution of several surfactants (terpineol, SDS, CTAB, Triton X-100, Triton X-45 at various concentrations. Generally, these features are observed: Initially a surfactant addition leads to an increase of the oscillation frequency (though surface tension is decreasing; this effect can be attributed to the increasing interfacial elasticity. The decay time of oscillation is strongly decreasing, as a consequence of energy dissipation linked with Marangoni stresses. At a certain critical concentration, frequency decreases abruptly and the decay time passes by a minimum. With further addition of surfactant, frequency decreases, and the decay time slightly lengthens. Above critical micelle concentration, all these parameters stabilize. Interestingly, the critical concentration, at which frequency drop occurs, depends on mode order. This clearly shows that the frequency drop and minimum decay time are not a consequence of some abrupt change of interfacial properties, but are a consequence of some phenomena, which still need to be explained.

Interactions between Surfactants in Solution and Electrospun Protein Fibers: Effects on Release Behavior and Fiber Properties

DEFF Research Database (Denmark)

Boutrup Stephansen, Karen; García-Díaz, María; Jessen, Flemming

2016-01-01

, and drug delivery. In the present study, we present a systematic investigation of how surfactants and proteins, as physiologically relevant components, interact with insulin-loaded fish sarcoplasmic protein (FSP) electrospun fibers (FSP-Ins fibers) in solution and thereby affect fiber properties...... such as accessible surface hydrophilicity, physical stability, and release characteristics of an encapsulated drug. Interactions between insulin-loaded protein fibers and five anionic surfactants (sodium taurocholate, sodium taurodeoxycholate, sodium glycocholate, sodium glycodeoxycholate, and sodium dodecyl sulfate......), a cationic surfactant (benzalkonium chloride), and a neutral surfactant (Triton X-100) were studied. The anionic surfactants increased the insulin release in a concentration-dependent manner, whereas the neutral surfactant had no significant effect on the release. Interestingly, only minute amounts...

Effects of Surfactants on the Rate of Chemical Reactions

Directory of Open Access Journals (Sweden)

B. Samiey

2014-01-01

Full Text Available Surfactants are self-assembled compounds that depend on their structure and electric charge can interact as monomer or micelle with other compounds (substrates. These interactions which may catalyze or inhibit the reaction rates are studied with pseudophase, cooperativity, and stoichiometric (classical models. In this review, we discuss applying these models to study surfactant-substrate interactions and their effects on Diels-Alder, redox, photochemical, decomposition, enzymatic, isomerization, ligand exchange, radical, and nucleophilic reactions.

Use of surfactants to control island size and density

Science.gov (United States)

Merrell, Jason; Liu, Feng; Stringfellow, Gerald B.

2017-08-15

Methods of controlling island size and density on an OMVPE growth film may comprise adding a surfactant at a critical concentration level, allowing a growth phase for a first period of time, and ending the growth phase when desired island size and density are achieved. For example, the island size and density of an OMVPE grown InGaN thin film may be controlled by adding an antimony surfactant at a critical concentration level.

Micro-scale displacement of NAPL by surfactant and microemulsion in heterogeneous porous media

Science.gov (United States)

Javanbakht, Gina; Arshadi, Maziar; Qin, Tianzhu; Goual, Lamia

2017-07-01

Industrial processes such as remediation of oil-contaminated aquifers and enhanced oil recovery (EOR) often utilize chemical additives to increase the removal of non-aqueous phase liquids (NAPLs) from subsurface formations. Although the majority of crude oils are classified as LNAPLs, they often contain heavy molecules (DNAPLs) such as asphaltenes that tend to adsorb on minerals and alter their wettability. Effective additives are therefore those that can reduce the threshold capillary pressure, thus mobilizing LNAPL inside pore spaces and solubilizing DNAPL from rock surfaces. Nonionic surfactants in brine have often been injected to oil or contaminated aquifer formations in order to enhance NAPL displacement through IFT reduction. Recent studies revealed that surfactant-based microemulsions have a higher tendency to alter the wettability of surfaces, compared to surfactants alone, leading to more effective NAPL removal. However, the impact of these additives on pore-scale displacement mechanisms and multi-phase fluid occupancy in porous media is, to date, still unclear. In this study, x-ray microtomography experiments were performed to investigate the impact of surfactants and microemulsions on the mobilization and solubilization of NAPL in heterogeneous rocks. Saturation profiles indicated that an incremental NAPL removal was attained by addition of microemulsion to brine, compared with surfactant. Residual cluster size distributions revealed that microemulsions could break up large clusters into smaller disconnected ones, improving their mobilization in the rock. In-situ contact angle measurements showed that microemulsions could reverse the wettability of rough contaminated surfaces to a higher extent than surfactants. Unlike surfactant alone, the surfactant-solvent blend in the carrier fluid of microemulsions was able to penetrate rough grain surfaces, particularly those of dolomite cement, and desorb asphaltenes in the form of small-emulsified NAPL droplets

Photoactivation and perturbation of photoluminescent properties of aqueous ZnS nanoparticles: Probing the surfactant-semiconductor interfaces

International Nuclear Information System (INIS)

Mehta, S.K.; Kumar, Sanjay

2011-01-01

Graphical abstract: The variation in PL emission intensity of growing ZnS NPs during first hour of their growth depends upon the nature of surfactants used for their stabilization. Highlights: ► Photoluminescence (PL) intensity of growing ZnS NPs increases linearly with time. ► Significant PL enhancement in anionic surfactant stabilized ZnS NPs on irradiation. ► PL decay with delay time after removing from UV-irradiation in all the surfactants. ► Better PL stability of ZnS NPs stabilized in anionic surfactants than cationic ones. - Abstract: The in situ photochemistry of aqueous colloidal ZnS has been studied in relation to variety of the surfactants as surface passivating agents. The photoluminescence (PL) intensity of ZnS nanoparticles (NPs) has been drastically enhanced as compared to their bare counterparts due to surface passivation by surfactants depending upon their molecular structure. Cationic surfactants of alkyltrimethylammonium bromide series with different chain lengths (C 16 , C 14 and C 12 ) have been tested. The PL emission of ZnS NPs decreases with decrease in chain length because of ineffective stabilization and passivation of surface because the larger sized NPs were produced in the surfactant with smaller chain length. On the other hand, three anionic surfactants with C 12 chain length with different head groups have been capable of comparatively effective passivation to produce stable NPs with better luminescence. The changing nature of surface states during growth and long time ripening of ZnS NPs has also been monitored by comparing time evolution PL emission in different surfactants. The influence of UV-light irradiation in enhancing the PL emission has been found to be surfactant structure dependent with maximum enhancement observed with the surfactants having π-electrons in their head group functionalities. The anionic surfactants also display better tendency to retain the enhanced PL of ZnS NPs for longer time durations.

Respiratory and Systemic Effects of LASSBio596 Plus Surfactant in Experimental Acute Respiratory Distress Syndrome

Directory of Open Access Journals (Sweden)

Johnatas Dutra Silva

2016-02-01

Full Text Available Background/Aims: Exogenous surfactant has been proposed as adjunctive therapy for acute respiratory distress syndrome (ARDS, but it is inactivated by different factors present in the alveolar space. We hypothesized that co-administration of LASSBio596, a molecule with significant anti-inflammatory properties, and exogenous surfactant could reduce lung inflammation, thus enabling the surfactant to reduce edema and improve lung function, in experimental ARDS. Methods: ARDS was induced by cecal ligation and puncture surgery in BALB/c mice. A sham-operated group was used as control (CTRL. After surgery (6 hours, CTRL and ARDS animals were assigned to receive: (1 sterile saline solution; (2 LASSBio596; (3 exogenous surfactant or (4 LASSBio596 plus exogenous surfactant (n = 22/group. Results: Regardless of exogenous surfactant administration, LASSBio596 improved survival rate and reduced collagen fiber content, total number of cells and neutrophils in PLF and blood, cell apoptosis, protein content in BALF, and urea and creatinine levels. LASSBio596 plus surfactant yielded all of the aforementioned beneficial effects, as well as increased BALF lipid content and reduced surface tension. Conclusion: LASSBio596 exhibited major anti-inflammatory and anti-fibrogenic effects in experimental sepsis-induced ARDS. Its association with surfactant may provide further advantages, potentially by reducing surface tension.

Some aspects of surfactant action mechanism in the organic reagents - metal ions systems

Energy Technology Data Exchange (ETDEWEB)

Chernova, R K; Shtykov, S N; Beloliptseva, G M; Sukhova, L K; Amelin, V G; Kulapina, E G [Saratovskij Gosudarstvennyj Univ. (USSR)

1984-06-01

Results are reviewed of investigations into the interaction of ions of Mo(6), W, Zr, Be, Sc, Nb, Ta, J, rare earths, a. o. with organic reagents of triphenylmethane class in the 8M H/sub 2/SO/sub 4/-pH14 acidity range and the 1x10/sup -3/-5x10/sup -6/ M concentration range both in the presence and absence of different surfactant type (cetylpyridine, methyltrimethylammonium, synthanols, etc). Three types of effects, determining enhancement of the sensitivity and selectivity of reactions jn the Me-R-surfactant systems, were determined: an increase in the number of coordinated ligands, the activating effect of cation surfactants resulting in a potential complexing in acid media, multicenter interaction of polydentate ligands both via chelating groups and auxochrome groups in the presence of cation surfactants. Protolytic and flotation properties of ionic associates are considered. The observed effects are explained from the viewpoint of electrostatic and hydrophobic interactions in the R-surfactant systems, observed by the methods of NMR, polarography amperometry, conductometry. A possible use of the investigated M-R-surfactant systems as complexonometric indicators was evaluated. A possibility was shown of using them for direct titrimetric determination of hundredth milligram portions of Cu, Ga, In and Sc at a titrant concentratjon of less than 0.01 M. It follows from the estimation of basic optical parameters of the Me-R-surfactant systems that detection.

Bacterial degradation of emulsified crude oil and the effects of various surfactants

International Nuclear Information System (INIS)

Bruheim, P.; Bredholt, H.; Eimhjellen, K.

1997-01-01

The effects of surfactants on the oxidation rate of alkanes in crude oil were investigated using a selected bacterial species, Rhodococcus sp., pregrown to various growth stages. Oxidation rates were measured in a three-hour period by Warburg respirometry. Response to emulsified oil was found to be dependent on the physiological state of the bacteria. In the exponential growth phase oxidation rates were negatively affected by surfactant amendment, whereas in the stationary growth phase oxidation rates appear to have been stimulated. The stimulatory effect was attributed to the chemical structure and physico-chemical properties of the surfactants. Surfactants with hydrophilic-lipophilic balance values (HLB) in the intermediate range of 8-12 gave the best values. Neither the commercial dispersants nor the biosurfactants exhibited any stimulative effects. 21 refs., 4 tabs., 1 fig

Reactive surfactants in heterophase polymerization

NARCIS (Netherlands)

Guyot, A.; Tauer, K.; Asua, J.M.; Es, van J.J.G.S.; Gauthier, C.; Hellgren, A.C.; Sherrington, D.C.; Montoya-Goni, A.; Sjöberg, M.; Sindt, O.; Vidal, F.F.M.; Unzue, M.; Schoonbrood, H.A.S.; Schipper, E.T.W.M.; Lacroix-Desmazes, P.

1999-01-01

This paper summarizes the work carried out during 3 years in a Network of the program "Human Capital and Mobility" of the European Union CHRX 93-0159 entitled "Reactive surfactants in heterophase polymerization for high performance polymers". A series of about 25 original papers will be published in

The effect of surfactants on path instability of a rising bubble

Science.gov (United States)

Tagawa, Yoshiyuki; Takagi, Shu; Matsumoto, Yoichiro

2013-11-01

We experimentally investigate the surfactant effect on path instability of an air bubble rising in quiescent water. An addition of surfactant varies the gas-water boundary condition from zero shear stress to non-zero shear stress. We report three main findings: firstly, while the drag force acting on the bubble increases with the surfactant concentration as expected, the lift force shows a non-monotonic behavior; secondly, the transient trajectory starting from helical to zigzag is observed, which has never been reported in the case of purified water; lastly, a bubble with the intermediate slip conditions between free-slip and no-slip show a helical motion for a broad range of the Reynolds number. Aforementioned results are rationalized by considering the adsorption-desorption kinetics of the surfactants on gas-water interface and the wake dynamics. Y.T. thanks for financial support from Grant-in-Aid for JSPS Fellows (20-10701). We also thank for Grant-in-Aid for Scientific Research (B) (21360079).

The effects of exogenous surfactant administration on ventilation-induced inflammation in mouse models of lung injury.

Science.gov (United States)

Puntorieri, Valeria; Hiansen, Josh Qua; McCaig, Lynda A; Yao, Li-Juan; Veldhuizen, Ruud A W; Lewis, James F

2013-11-20

Mechanical ventilation (MV) is an essential supportive therapy for acute lung injury (ALI); however it can also contribute to systemic inflammation. Since pulmonary surfactant has anti-inflammatory properties, the aim of the study was to investigate the effect of exogenous surfactant administration on ventilation-induced systemic inflammation. Mice were randomized to receive an intra-tracheal instillation of a natural exogenous surfactant preparation (bLES, 50 mg/kg) or no treatment as a control. MV was then performed using the isolated and perfused mouse lung (IPML) set up. This model allowed for lung perfusion during MV. In experiment 1, mice were exposed to mechanical ventilation only (tidal volume =20 mL/kg, 2 hours). In experiment 2, hydrochloric acid or air was instilled intra-tracheally four hours before applying exogenous surfactant and ventilation (tidal volume =5 mL/kg, 2 hours). For both experiments, exogenous surfactant administration led to increased total and functional surfactant in the treated groups compared to the controls. Exogenous surfactant administration in mice exposed to MV only did not affect peak inspiratory pressure (PIP), lung IL-6 levels and the development of perfusate inflammation compared to non-treated controls. Acid injured mice exposed to conventional MV showed elevated PIP, lung IL-6 and protein levels and greater perfusate inflammation compared to air instilled controls. Instillation of exogenous surfactant did not influence the development of lung injury. Moreover, exogenous surfactant was not effective in reducing the concentration of inflammatory cytokines in the perfusate. The data indicates that exogenous surfactant did not mitigate ventilation-induced systemic inflammation in our models. Future studies will focus on altering surfactant composition to improve its immuno-modulating activity.

Radioactive slurry waste treatment (2) - surfactants dose effects on filtration

International Nuclear Information System (INIS)

Jung, K. H.; Park, S. K.; Jung, W. S.; Baek, S. T.; Jung, K. J.

1999-01-01

The influence of anionic flocculants on the dewatering of radioactive slurries has been investigated in a laboratory-scale vacuum filtration unit. Simultaneously the influence of certain surfactants has also been investigated. Test results show that the flocculated filter cake generally contains higher residual water than the unflocculated cake. The non-ionic surfactant was effective in reducing the moisture content of the cake

COUPLING THE ALKALINE-SURFACTANT-POLYMER TECHNOLOGY AND THE GELATION TECHNOLOGY TO MAXIMIZE OIL PRODUCTION

Energy Technology Data Exchange (ETDEWEB)

Malcolm Pitts; Jie Qi; Dan Wilson

2004-10-01

Gelation technologies have been developed to provide more efficient vertical sweep efficiencies for flooding naturally fractured oil reservoirs or more efficient areal sweep efficiency for those with high permeability contrast ''thief zones''. The field proven alkaline-surfactant-polymer technology economically recovers 15% to 25% OOIP more oil than waterflooding from swept pore space of an oil reservoir. However, alkaline-surfactant-polymer technology is not amenable to naturally fractured reservoirs or those with thief zones because much of injected solution bypasses target pore space containing oil. This work investigates whether combining these two technologies could broaden applicability of alkaline-surfactant-polymer flooding into these reservoirs. A prior fluid-fluid report discussed interaction of different gel chemical compositions and alkaline-surfactant-polymer solutions. Gel solutions under dynamic conditions of linear corefloods showed similar stability to alkaline-surfactant-polymer solutions as in the fluid-fluid analyses. Aluminum-polyacrylamide, flowing gels are not stable to alkaline-surfactant-polymer solutions of either pH 10.5 or 12.9. Chromium acetate-polyacrylamide flowing and rigid flowing gels are stable to subsequent alkaline-surfactant-polymer solution injection. Rigid flowing chromium acetate-polyacrylamide gels maintained permeability reduction better than flowing chromium acetate-polyacrylamide gels. Silicate-polyacrylamide gels are not stable with subsequent injection of either a pH 10.5 or a 12.9 alkaline-surfactant-polymer solution. Neither aluminum citrate-polyacrylamide nor silicate-polyacrylamide gel systems produced significant incremental oil in linear corefloods. Both flowing and rigid flowing chromium acetate-polyacrylamide gels produced incremental oil with the rigid flowing gel producing the greatest amount. Higher oil recovery could have been due to higher differential pressures across cores. None of

Adsorption of naphthalene and ozone on atmospheric air/ice interfaces coated with surfactants: a molecular simulation study.

Science.gov (United States)

Liyana-Arachchi, Thilanga P; Valsaraj, Kalliat T; Hung, Francisco R

2012-03-15

The adsorption of gas-phase naphthalene and ozone molecules onto air/ice interfaces coated with different surfactant species (1-octanol, 1-hexadecanol, or 1-octanal) was investigated using classical molecular dynamics (MD) simulations. Naphthalene and ozone exhibit a strong preference to be adsorbed at the surfactant-coated air/ice interfaces, as opposed to either being dissolved into the bulk of the quasi-liquid layer (QLL) or being incorporated into the ice crystals. The QLL becomes thinner when the air/ice interface is coated with surfactant molecules. The adsorption of both naphthalene and ozone onto surfactant-coated air/ice interfaces is enhanced when compared to bare air/ice interface. Both naphthalene and ozone tend to stay dissolved in the surfactant layer and close to the QLL, rather than adsorbing on top of the surfactant molecules and close to the air region of our systems. Surfactants prefer to orient at a tilted angle with respect to the air/ice interface; the angular distribution and the most preferred angle vary depending on the hydrophilic end group, the length of the hydrophobic tail, and the surfactant concentration at the air/ice interface. Naphthalene prefers to have a flat orientation on the surfactant coated air/ice interface, except at high concentrations of 1-hexadecanol at the air/ice interface; the angular distribution of naphthalene depends on the specific surfactant and its concentration at the air/ice interface. The dynamics of naphthalene molecules at the surfactant-coated air/ice interface slow down as compared to those observed at bare air/ice interfaces. The presence of surfactants does not seem to affect the self-association of naphthalene molecules at the air/ice interface, at least for the specific surfactants and the range of concentrations considered in this study.

Degradation of surfactant-modified montmorillonites in HCl

International Nuclear Information System (INIS)

Madejová, Jana; Pálková, Helena; Jankovič, Ľuboš

2012-01-01

The effect of surfactant size on the extent of montmorillonites decomposition in HCl was investigated. Na-SAz montmorillonite and tetraalkylammonium salts of alkyl-chains length increasing from methyl- Me 4 N to pentyl- Pe 4 N were used for organo-montmorillonites preparation. Decreasing intensity of d 001 diffraction proved destruction of montmorillonite structure connected with gradual surfactant release. A shift of the SiO stretching band to 1097 cm −1 confirmed formation of amorphous silica phase. A new band near 7315 cm −1 corresponding to SiOH overtone revealed creation of protonated silica. This band was observed in the spectra of all acid-treated samples, also in those with minor decomposition of the structure. The size of the cations significantly affected decomposition of montmorillonites in HCl. The less stable were Na-SAz and Me 4 N-SAz in which the content of octahedral atoms dropped to ∼5% of their original values upon 8 h treatments. Et 4 N-SAz and Pr 4 N-SAz were slightly more resistant mainly at short times. Bu 4 N-SAz and Pe 4 N-SAz showed the least structural modifications, only 50% and 35% of octahedral atoms, respectively, were released into solution within 8 h treatments. This observation proves that bulky alkylammonium cations covering the inner and outer surfaces of montmorillonite prevent effectively the access of protons to the layers protecting the mineral from degradation in the acid. - Highlights: ► Hybrid materials were prepared from montmorillonite and alkylammonium cations with short alkyl chains. ► The effect of surfactant on organo-montmorillonites dissolution in HCl was studied. ► With increasing size of cation the extent of montmorillonite decomposition decreased. ► Bulky surfactants prevent the access of protons to the layers and thus protect montmorillonite from degradation.

Two-phase aqueous micellar systems: an alternative method for protein purification

Directory of Open Access Journals (Sweden)

Rangel-Yagui C. O.

2004-01-01

Full Text Available Two-phase aqueous micellar systems can be exploited in separation science for the extraction/purification of desired biomolecules. This article reviews recent experimental and theoretical work by Blankschtein and co-workers on the use of two-phase aqueous micellar systems for the separation of hydrophilic proteins. The experimental partitioning behavior of the enzyme glucose-6-phosphate dehydrogenase (G6PD in two-phase aqueous micellar systems is also reviewed and new results are presented. Specifically, we discuss very recent work on the purification of G6PD using: i a two-phase aqueous micellar system composed of the nonionic surfactant n-decyl tetra(ethylene oxide (C10E4, and (ii a two-phase aqueous mixed micellar system composed of C10E4 and the cationic surfactant decyltrimethylammonium bromide (C10TAB. Our results indicate that the two-phase aqueous mixed (C10E4/C10TAB micellar system can improve significantly the partitioning behavior of G6PD relative to that observed in the two-phase aqueous C10E4 micellar system.

Adsorption of surfactant ions and binding of their counterions at an air/water interface.

Science.gov (United States)

Tagashira, Hiroaki; Takata, Youichi; Hyono, Atsushi; Ohshima, Hiroyuki

2009-01-01

An expression for the surface tension of an aqueous mixed solution of surfactants and electrolyte ions in the presence of the common ions was derived from the Helmholtz free energy of an air/water surface. By applying the equation to experimental data for the surface tension, the adsorption constant of surfactant ions onto the air/water interface, the binding constant of counterions on the surfactants, and the surface potential and surface charge density of the interface were estimated. The adsorption constant and binding constant were dependent on the species of surfactant ion and counterion, respectively. Taking account of the dependence of surface potential and surface charge density on the concentration of electrolyte, it was suggested that the addition of electrolyte to the aqueous surfactant solution brings about the decrease in the surface potential, the increase in the surface density of surfactant ions, and consequently, the decrease in the surface tension. Furthermore, it was found that the configurational entropy plays a predominant role for the surface tension, compared to the electrical work.

NATURAL SURFACTANTS AND THEIR USE IN FOOD INDUSTRY

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František Kreps

2011-12-01

Full Text Available Microorganisms produce wide range of surfactants, generally called biosurfactants. These compounds are mainly divided according to their molecular weight, physico - chemical properties and mode of action. Saponins, plant surfactants, have properties of  soap and they are high foaming and therefore are used in cosmetic (shampoos, liquid soaps et cetera and food industry (sweeteners, food additives into the effervescents et cetera. Most of them are spread in plants of agriculture importance and some of them are basic segments in human food. They often occur in plants (in more then 100 species. Saponins can be find in vegetables as a soya, a bean, a lentil, a spinach, a tomato, a potato, a garlic, a onion. Today biosurfactants are mainly used in bioremediation but they can be utilized in many sectors of food industry. We have paid attention to some microbial and plant surfactants and their prospects of exploitation in this industry.doi:10.5219/170 

Theoretical model to investigate the alkyl chain and anion dependent interactions of gemini surfactant with bovine serum albumin.

Science.gov (United States)

Vishvakarma, Vijay K; Kumari, Kamlesh; Patel, Rajan; Dixit, V S; Singh, Prashant; Mehrotra, Gopal K; Chandra, Ramesh; Chakrawarty, Anand Kumar

2015-05-15

Surfactants are used to prevent the irreversible aggregation of partially refolded proteins and they also assist in protein refolding. We have reported the design and screening of gemini surfactant to stabilize bovine serum albumin (BSA) with the help of computational tool (iGEMDOCK). A series of gemini surfactant has been designed based on bis-N-alkyl nicotinate dianion via varying the alkyl group and anion. On changing the alkyl group and anion of the surfactant, the value of Log P changes means polarity of surfactant can be tuned. Further, the virtual screening of the gemini surfactant has been carried out based on generic evolutionary method. Herein, thermodynamic data was studied to determine the potential of gemini surfactant as BSA stabilizer. Computational tools help to find out the efficient gemini surfactant to stabilize the BSA rather than to use the surfactant randomly and directionless for the stabilization. It can be confirmed through the experimental techniques. Previously, researcher synthesized one of the designed and used gemini surfactant to stabilize the BSA and their interactions were confirmed through various techniques and computational docking. But herein, the authors find the most competent gemini surfactant to stabilize BSA using computational tools on the basis of energy score. Different from the single chain surfactant, the gemini surfactants exhibit much stronger electrostatic and hydrophobic interactions with the protein and are thus effective at much lower concentrations. Based on the present study, it is expected that gemini surfactants may prove useful in the protein stabilization operations and may thus be effectively employed to circumvent the problem of misfolding and aggregation. Copyright © 2015 Elsevier B.V. All rights reserved.

Catheter and Laryngeal Mask Endotracheal Surfactant Therapy: the CALMEST approach as a novel MIST technique.

Science.gov (United States)

Vannozzi, Ilaria; Ciantelli, Massimiliano; Moscuzza, Francesca; Scaramuzzo, Rosa T; Panizza, Davide; Sigali, Emilio; Boldrini, Antonio; Cuttano, Armando

2017-10-01

Neonatal respiratory distress syndrome (RDS) is a major cause of mortality and morbidity among preterm infants. Although the INSURE (INtubation, SURfactant administration, Estubation) technique for surfactant replacement therapy is so far the gold standard method, over the last years new approaches have been studied, i.e. less invasive surfactant administration (LISA) or minimally invasive surfactant therapy (MIST). Here we propose an originally modified MIST, called CALMEST (Catheter And Laryngeal Mask Endotracheal Surfactant Therapy), using a particular laryngeal mask as a guide for a thin catheter to deliver surfactant directly in the trachea. We performed a preliminary study on a mannequin and a subsequent in vivo pilot trial. This novel procedure is quick, effective and well tolerated and might represent an improvement in reducing neonatal stress. Ultimately, CALMEST offers an alternative approach that could be extremely useful for medical staff with low expertise in laryngoscopy and intubation.

Surfactant-assisted sacrificial template-mediated synthesis

Indian Academy of Sciences (India)

... spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopyand photoluminescence studies. Influence of surfactant and solvents on morphology and luminescence of the final product in sacrificial template-assisted method has been investigated in detail.

Lung surfactant microbubbles increase lipophilic drug payload for ultrasound-targeted delivery.

Science.gov (United States)

Sirsi, Shashank R; Fung, Chinpong; Garg, Sumit; Tianning, Mary Y; Mountford, Paul A; Borden, Mark A

2013-01-01

The cavitation response of circulating microbubbles to targeted ultrasound can be used for noninvasive, site-specific delivery of shell-loaded materials. One challenge for microbubble-mediated delivery of lipophilic compounds is the limitation of drug loading into the microbubble shell, which is commonly a single phospholipid monolayer. In this study, we investigated the use of natural lung surfactant extract (Survanta(®), Abbott Nutrition) as a microbubble shell material in order to improve drug payload and delivery. Pulmonary surfactant extracts such as Survanta contain hydrophobic surfactant proteins (SP-B and SP-C) that facilitate lipid folding and retention on lipid monolayers. Here, we show that Survanta-based microbubbles exhibit wrinkles in bright-field microscopy and increased lipid retention on the microbubble surface in the form of surface-associated aggregates observed with fluorescence microscopy. The payload of a model lipophilic drug (DiO), measured by flow cytometry, increased by over 2-fold compared to lipid-coated microbubbles lacking SP-B and SP-C. Lung surfactant microbubbles were highly echogenic to contrast enhanced ultrasound imaging at low acoustic intensities. At higher ultrasound intensity, excess lipid was observed to be acoustically cleaved for localized release. To demonstrate targeting, a biotinylated lipopolymer was incorporated into the shell, and the microbubbles were subjected to a sequence of radiation force and fragmentation pulses as they passed through an avidinated hollow fiber. Lung surfactant microbubbles showed a 3-fold increase in targeted deposition of the model fluorescent drug compared to lipid-only microbubbles. Our results demonstrate that lung surfactant microbubbles maintain the acoustic responsiveness of lipid-coated microbubbles with the added benefit of increased lipophilic drug payload.

Recycling of surfactant template in mesoporous MCM-41 synthesis

Science.gov (United States)

Lai, J. Y.; Twaiq, F.; Ngu, L. H.

2017-06-01

The recycling of surfactant template is investigated through the reuse of the surfactant template in the mesoporous MCM-41 synthesis process. In the synthesis of MCM-41, tetraethylorthosilicate (TEOS) solution in water was utilized as the silica source while hexadecyltrimethylammonium bromide (CTAB) solution in ethyl alcohol was used as a surfactant template. The synthesized gel is formed thoroughly by mixing the two solutions under acid conditions with a pH value of 0.5 for 1 hour and kept for crystallization for 48 hours. The as-synthesized MCM-41 powder is recovered by filtration while the filtrate (mother liquor) was then reused for the second synthesis cycle. The synthesis procedure was repeated till no further solid product was formed. The synthesized gel was not produced in the unifying solution in the fifth cycle of MCM-41 synthesis. The quality of the calcined MCM-41 powder produced in each synthesis cycle was evaluated by calculating the amount of MCM-41 produced and the surface area of the powder product. The result showed that 1.28, 0.37, 1.64, 1.90 and 0.037 g were obtained in the 1st, 2nd, 3rd, 4th and 5th synthesis cycle, respectively. The surface area of the powder produced was found to be 1170, 916, 728, and 508 m2/g for 1st, 2nd, 3rd and 4th respectively. The concentration of the surfactant template has reached value lower than the critical micelle concentration (CMC) and remained constant after the 4th cycle. There was no further formation of gel due to low availability in the interaction between silicate anions and surfactant cations when the amount of TEOS was fixed for every synthesis cycle.

The effect of surfactants on the electropolishing behavior of copper in orthophosphoric acid

Energy Technology Data Exchange (ETDEWEB)

Taha, A.A., E-mail: asia_taha@yahoo.com; Ahmed, A.M.; Rahman, H.H. Abdel; Abouzeid, F.M.

2013-07-15

The electropolishing behavior of copper was studied in orthophosphoric acid with Triton X-100, sodium dodecyl sulphate and cetyl pyridinium chloride as additives for improving the finish obtained on copper surface. This was investigated by measuring and comparing anode potential-limiting current relationships in solutions of gradually increasing concentration of surfactants. The addition of surfactants to the electropolishing solution results in a lower limiting current. This confirms the mass transport of dissolved species from the anode surface to the bulk of solution as the rate-determining step in the presence of three surfactants in all concentrations investigated. Scanning electron microscope (SEM), atomic force microscope (AFM) and measured brightness values were used to investigate the copper surface after electropolishing and the results were compared to polishing done in absence of surfactants. According to SEM images and brightness values, addition of Triton X-100 was effective to enhance levelling and brightening more than sodium dodecyl sulphate and cetyl pyridinium chloride. AFM analysis showed that the roughness values (R{sub a}) for an electropolished copper surface, in presence of surfactants, is significantly lower than in absence of surfactants. Different reaction conditions and the physical properties of solutions are studied to obtain dimensionless correlation among all these parameters.

Current Issues and Challenges in the Use of Aerosolized Surfactant for Respiratory Distress Syndrome in the Newborns

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Dion Darius Samsudin

2013-08-01

Full Text Available BACKGROUND: Surfactant replacement therapy is a recognized treatment for respiratory distress syndrome (RDS in the newborns. Over the past 30 years, human and animal trials have been performed regarding administration of aerosolized surfactant to the injured lung, however the result has been unsatisfactory when compared with instilled surfactant delivery via endotracheal tube (ETT. This review aims to investigate the current issues, challenges and future recommendation of aerosolized surfactant therapy. CONTENT: Five randomized clinical trials in humans and 13 animal trials met the inclusion criteria and were reviewed. Most animal trials agree that this method of treatment is feasible. However, human trials presented conflicting results, and generally showed it to be ineffective. When compared with surfactant delivery via ETT, aerosolized surfactant is less effective in improving respiratory function. SUMMARY: The current data from human trials does not support the implementation of aerosolized surfactant therapy to treat newborns with RDS. Further research is necessary to improve nebulization, delivery, distribution and deposition in the lung, to investigate aerosolized surfactant delivery via ETT and to determine the appropriate dose. KEYWORDS: surfactant, aerosol, prematurity, respiratory distress syndrome.

Influence of surfactants on gas-hydrate formation' kinetics in water-oil emulsion

Science.gov (United States)

Zemenkov, Yu D.; Shirshova, A. V.; Arinstein, E. A.; Shuvaev, A. N.

2018-05-01

The kinetics of gas hydrate formation of propane in a water-oil emulsion is experimentally studied when three types of surfactants (SAA (surface acting agent)) - anionic type emulsifiers - are added to the aqueous phase. It is shown that all three types of surfactants decelerate the growth of the gas-hydrate in the emulsion and can be considered as anti-agglutinating and kinetic low-dose inhibitors. The most effective inhibitor of hydrate formation in water-oil emulsion of SV-102 surfactant was revealed. For comparison, experimental studies of gas-hydrate formation under the same conditions for bulk water have been carried out. It is shown that in bulk water, all the surfactants investigated act as promoters (accelerators) of hydrate formation. A qualitative explanation of the action mechanisms of emulsifiers in the process of gas-hydrate formation in water-oil emulsion is given.

The Accelerated Late Adsorption of Pulmonary Surfactant

Science.gov (United States)

2011-01-01

Adsorption of pulmonary surfactant to an air−water interface lowers surface tension (γ) at rates that initially decrease progressively, but which then accelerate close to the equilibrium γ. The studies here tested a series of hypotheses concerning mechanisms that might cause the late accelerated drop in γ. Experiments used captive bubbles and a Wilhelmy plate to measure γ during adsorption of vesicles containing constituents from extracted calf surfactant. The faster fall in γ reflects faster adsorption rather than any feature of the equation of state that relates γ to surface concentration (Γ). Adsorption accelerates when γ reaches a critical value rather than after an interval required to reach that γ. The hydrophobic surfactant proteins (SPs) represent key constituents, both for reaching the γ at which the acceleration occurs and for producing the acceleration itself. The γ at which rates of adsorption increase, however, is unaffected by the Γ of protein in the films. In the absence of the proteins, a phosphatidylethanolamine, which, like the SPs, induces fusion of the vesicles with the interfacial film, also causes adsorption to accelerate. Our results suggest that the late acceleration is characteristic of adsorption by fusion of vesicles with the nascent film, which proceeds more favorably when the Γ of the lipids exceeds a critical value. PMID:21417351

Alkali/Surfactant/Polymer Flooding in the Daqing Oilfield Class II Reservoirs Using Associating Polymer

Directory of Open Access Journals (Sweden)

Ru-Sen Feng

2013-01-01

Full Text Available Hydrophobically modified associating polyacrylamide (HAPAM has good compatibility with the Daqing heavy alkylbenzene sulfonate surfactant. The HAPAM alkali/surfactant/polymer (ASP system can generate ultralow interfacial tension in a wide range of alkali/surfactant concentrations and maintain stable viscosity and interfacial tension for 120 days. The HAPAM ASP system has good injectivity for the Daqing class II reservoirs (100–300 × 10−3 μm2 and can improve oil recovery by more than 25% on top of water flooding. In the presence of both the alkali and the surfactant, the surfactant interacts with the associating groups of the polymer to form more micelles, which can significantly enhance the viscosity of the ASP system. Compared with using HPAM (Mw = 2.5 MDa, using HAPAM can reduce the polymer use by more than 40%.

Influence of chemical surfactants on the biodegradation of crude oil by a mixed bacterial culture

International Nuclear Information System (INIS)

Van Hamme, J.D.; Ward, O.P.

1999-01-01

A study was conducted in which the effects of surfactant physicochemical properties on crude oil biodegradation by a mixed-bacterial culture were examined. The effects of hydrophile-lipophile balance (HLB) and molecular structure on the biodegradation of Bow River crude oil were determined. It was shown that chemical surfactants have the potential to improve crude oil biodegradation in complex microbial systems. Surfactant selection should consider factors such as molecular structure, HLB and surfactant concentration. 26 refs., 4 tabs., 3 figs

Adsorption behavior of hydrophobin and hydrophobin/surfactant mixtures at the air-water interface.

Science.gov (United States)

Zhang, Xiaoli L; Penfold, Jeffrey; Thomas, Robert K; Tucker, Ian M; Petkov, Jordan T; Bent, Julian; Cox, Andrew; Campbell, Richard A

2011-09-20

The adsorption of the surface-active protein hydrophobin, HFBII, and the competitive adsorption of HFBII with the cationic, anionic, and nonionic surfactants hexadecyltrimethylammonium bromide, CTAB, sodium dodecyl sulfate, SDS, and hexaethylene monododecyl ether, C(12)E(6), has been studied using neutron reflectivity, NR. HFBII adsorbs strongly at the air-water interface to form a dense monolayer ∼30 Å thick, with a mean area per molecule of ∼400 Å(2) and a volume fraction of ∼0.7, for concentrations greater than 0.01 g/L, and the adsorption is independent of the solution pH. In competition with the conventional surfactants CTAB, SDS, and C(12)E(6) at pH 7, the HFBII adsorption totally dominates the surface for surfactant concentrations less than the critical micellar concentration, cmc. Above the cmc of the conventional surfactants, HFBII is displaced by the surfactant (CTAB, SDS, or C(12)E(6)). For C(12)E(6) this displacement is only partial, and some HFBII remains at the surface for concentrations greater than the C(12)E(6) cmc. At low pH (pH 3) the patterns of adsorption for HFBII/SDS and HFBII/C(12)E(6) are different. At concentrations just below the surfactant cmc there is now mixed HFBII/surfactant adsorption for both SDS and C(12)E(6). For the HFBII/SDS mixture the structure of the adsorbed layer is more complex in the region immediately below the SDS cmc, resulting from the HFBII/SDS complex formation at the interface. © 2011 American Chemical Society

Surface properties and aggregate morphology of partially fluorinated carboxylate-type anionic gemini surfactants.

Science.gov (United States)

Yoshimura, Tomokazu; Bong, Miri; Matsuoka, Keisuke; Honda, Chikako; Endo, Kazutoyo

2009-11-01

Three anionic homologues of a novel partially fluorinated carboxylate-type anionic gemini surfactant, N,N'-di(3-perfluoroalkyl-2-hydroxypropyl)-N,N'-diacetic acid ethylenediamine (2C(n)(F) edda, where n represents the number of carbon atoms in the fluorocarbon chain (4, 6, and 8)) were synthesized. In these present gemini surfactants, the relatively small carboxylic acid moieties form hydrophilic head groups. The surface properties or structures of the aggregates of these surfactants are strongly influenced by the nonflexible fluorocarbons and small head groups; this is because these surfactants have a closely packed molecular structure. The equilibrium surface tension properties of these surfactants were measured at 298.2K for various fluorocarbon chain lengths. The plot of the logarithm of the critical micelle concentration (cmc) against the fluorocarbon chain lengths for 2C(n)(F) edda (n=4, 6, and 8) showed a minimum for n=6. Furthermore, the lowest surface tension of 2C(6)(F) edda at the cmc was 16.4mNm(-1). Such unique behavior has not been observed even in the other fluorinated surfactants. Changes in the shapes and sizes of these surfactant aggregate with concentration were investigated by dynamic light scattering and transmission electron microscopy (TEM). The TEM micrographs showed that in an aqueous alkali solution, 2C(n)(F) edda mainly formed aggregates with stringlike (n=4), cagelike (n=6), and distorted bilayer structures (n=8). The morphological changes in the aggregates were affected by the molecular structure composed of nonflexible fluorocarbon chains and flexible hydrocarbon chains.

Morphological alterations of exogenous surfactant inhibited by meconium can be prevented by dextran

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Stichtenoth Guido

2006-06-01

Full Text Available Abstract Background Surfactant dysfunction due to inhibition is involved in the pathophysiology of meconium aspiration syndrome. Dextran addition has been shown to reverse exogenous surfactant inactivation by meconium, but the precise mechanisms and the morphological correlate of this effect are yet unknown. Morphological surfactant analysis by transmission electron microscopy (TEM and stereology allows the differentiation of active (large aggregates = LA and inactive (small aggregates = SA subtypes. Methods To determine the in vitro effects of meconium and dextran addition on the morphology of a modified porcine natural surfactant (Curosurf, Curosurf samples were either incubated alone or together with meconium or with meconium and dextran, fixed and processed for TEM. Volume fractions of surfactant subtypes [lamellar body-like forms (LBL, multilamellar vesicles (MV, unilamellar vesicles (UV] were determined stereologically. Results All preparations contained LBL and MV (corresponding to LA as well as UV (corresponding to SA. The volume fraction of UV increased with addition of meconium and decreased with further addition of dextran. Correspondingly, the UV/(LBL+MV ratio (resembling the SA/LA ratio increased when meconium was added and decreased when dextran was added to the surfactant-meconium mixture. Conclusion Meconium causes alterations in the ultrastructural composition of Curosurf that can be visualized and analyzed by TEM and stereology. These alterations resemble an increase in the SA/LA ratio and are paralleled by an increase in minimum surface tension. Dextran prevents these effects and may therefore be a useful additive to exogenous surfactant preparations to preserve their structural and functional integrity, thereby improving their resistance to inactivation.