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Search Results: 1 - 10 of 649 matches for " surfactant "
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The Expression of Surfactant Proteins A and D in the Intestines and Pancreas of Murine Fetuses  [PDF]
Ryuta Saka, Hiroomi Okuyama, Kaoru Uchida, Kumiko Nakahira, Takashi Sasaki, Satoko Nose, Masahiro Nakayama, Masahiro Fukuzawa, Itaru Yanagihara
Open Journal of Pediatrics (OJPed) , 2014, DOI: 10.4236/ojped.2014.41002
Abstract:

Purpose: Surfactant proteins exist in the digestive tract and may play an important role in the host defense. However, the expression of surfactant proteins in the premature digestive system remains unclear. The aim of this study was to investigate the expression of surfactant proteins in the intes-tines and pancreas of murine fetuses. Methods: Immunostaining for SP-A and SP-D was assessed in the small intestine and pancreas of ICR murine fetuses on days 15, 16, 17 and 18 of gestation (normal duration of pregnancy: 19 - 21 days). RT-PCR was performed to detect the expression of spa and spd mRNA in the small intestine and pancreas on day 16, 17 and 18 of gestation. Results: Immunoreactivity for SP-A and SP-D in the

Urban Pond Water Contamination in India  [PDF]
Ankit Yadav, Pravin Kumar Sahu, Suryakant Chakradhari, Keshaw Prakash Rajhans, Shobhana Ramteke, Nohar Singh Dahariya, Gaurav Agnihotri, Khageshwar Singh Patel
Journal of Environmental Protection (JEP) , 2016, DOI: 10.4236/jep.2016.71005
Abstract: The stagnant water reservoirs in urban area of India are severely contaminated with surfactant and microbe due to anthropogenic activities. In this work, water quality of pond water of the most industrialized city: Raipur, CG, India is described. The concentration of surfactant in the term of sodium lauryl sulfate (SLS) in water (n = 16) is ranged from 7.0 - 27 mg/L with mean value of 17 ± 3 mg/L. All ponds are found to be contaminated with microbes i.e. bacteria, algae and fungi at elevated levels. The physico-chemical characteristics of the pond water are discussed.
Effects of Invasion of Water with and without Surfactant on the Oil Production and Flowback through an Oil Wet Matrix—A Microfluidic Chip Based Study  [PDF]
Srikanth Tangirala, James Sheng
Open Journal of Yangtze Oil and Gas (OJOGas) , 2018, DOI: 10.4236/ojogas.2018.34024
Abstract: The invasion of hydraulic fracturing fluids into the matrix through a relatively conductive fracture network causes capillary entrapment of the fluids that lead to the reduction of relative permeability of oil during production. Such a formation damage could be alleviated by the use of surfactants, however, their use does not always guarantee an efficient oil recovery. Through a microfluidic-chip based experimental study, the present work highlights the factors that control the later oil productivity and flowback especially through an oil-wetting matrix. The results from this study indicate that for an oil-wet formation, at shallow invasions, a water-based fracture fluid gives higher later oil production rates than a moderate IFT-reducing surfactant, and at deep invasions, the latter fluid gives better later oil production rates than the former. These results are very useful to the oil industry in making well informed decisions for selecting appropriate fracture fluids to stimulate oil-wet formations.
Electrochemical study of sulfide solution in the presence of surfactants
Yi Qing feng,Chen Qi yuan,Zhang Ping min
环境科学学报(英文版) , 1998,
Abstract: lectrochemicalstudyofsulfidesolutioninthepresenceofsurfactantsYiQingfengDepartmentofChemicalEnginering,XiangtanPolytechnicU...
The results of treating Hyaline membrane disease with Surfactant during 1 year at Ali-Asghar Hospital, neonatal intensive care unit
Naeri F,Samaei H
Tehran University Medical Journal , 1999,
Abstract: The routine intake of surfactant as a part of HMD (Hyaline Membrane Disease) treatment had significant effect on the prognosis of premature neonates. But since in our country this drug is not widely and routinely used, and there are not records about its use, we decided to make good on this shortcoming through a retrospective study. During 1 year, 54 neonates with HMD were admitted in Ali-Asghar's NICU, 30 of them had gestational age of less than 34 weeks and for 15 cases, surfactant was used. The results of treating this group were then compared with another group of neonates, who were not given this drug. From a statistical point of view, mortality, the length of the period in which the respirator was used, the use of high pressure in respirator, pneumothorax and pulmonary hemorrhage in neonates under treatment with surfactant was significantly less than those of the other group.
Application of Statistical Design Strategies to Optimize the Preparation of Cuo Nanoparticles by Hydrothermal Technique  [PDF]
Reda Mohamed, Ibreheem Mkhalid, Elham Azaam
Materials Sciences and Applications (MSA) , 2011, DOI: 10.4236/msa.2011.28132
Abstract: Synthesis of CuO nanoparticles by hydrothermal technique in presence of cetyltrimethylammonium bromide (CTAB) as surfactant was carried out by statistically designed experiments based on Box Behnken method. Reaction parameters as time, temperature and surfactant concentration have been studied to show their effect on CuO particle size and morphology. The results of experimental design indicate that the surfactant concentration, reaction time and temperature were significant in. CuO particles were characterized using XRD and SEM. These work findings showed that CuO nanoparticles were formed at 100oC. On other hand, their crystallinity was improved with rising temperature from 100 to 200oC to achieve particle size of CuO in the range of 49-92 nm.
Clay Modification by the Use of Organic Cations  [PDF]
Pankil Singla, Rajeev Mehta, Siddh Nath Upadhyay
Green and Sustainable Chemistry (GSC) , 2012, DOI: 10.4236/gsc.2012.21004
Abstract: To render layered silicates miscible with polymer matrices, one must convert the normally hydrophilic silicate surface to an organophilic one, making the intercalation of polymeric chain between silicate layers possible. This can be done by ion-exchange reactions with cationic surfactants. Sodium montmorillonite (Na-MMT) was modified with several organic cationic surfactants. Organoclays with water soluble surfactants were prepared by the traditional cation exchange reaction. An alternative procedure was used to prepare organoclays with water insoluble salts. The basal spacing and thermal behavior of organoclays were characterized by X-ray diffraction, XRD and Thermogravimetric analysis, TGA respectively.
Investigation of Chiral Molecular Micelles by NMR Spectroscopy and Molecular Dynamics Simulation  [PDF]
Kevin F. Morris, Eugene J. Billiot, Fereshteh H. Billiot, Kenny B. Lipkowitz, William M. Southerland, Yayin Fang
Open Journal of Physical Chemistry (OJPC) , 2012, DOI: 10.4236/ojpc.2012.24032
Abstract: NMR spectroscopy and Molecular Dynamics (MD) simulation analyses of the chiral molecular micelles poly-(Sodium Undecyl-(L,L)-Leucine-Valine) (poly-SULV) and poly-(Sodium Undecyl-(L,L)-Valine-Leucine) (poly-(SUVL)) are reported. Both molecular micelles are used as chiral selectors in electrokinetic chromatography and each consists of covalently linked surfactant chains with chiral dipeptide headgroups. To provide experimental support for the structures from MD simulations, NOESY spectra were used to identify protons in close spatial proximity. Results from the NOESY analyses were then compared to radial distribution functions from MD simulations. In addition, the hydrodynamic radii of both molecular micelles were calculated from NMR-derived diffusion coefficients. Corresponding radii from the MD simulations were found to be in agreement with these experimental results. NMR diffusion experiments were also used to measure association constants for polar and non-polar binaphthyl analytes binding to both molecular micelles. Poly (SUVL) was found to bind the non-polar analyte enantiomers more strongly, while the more polar analyte enantiomers interacted more strongly with poly(SULV). MD simulations in turn showed that poly(SULV) had a more open structure that gave greater access for water molecules to the dipeptide headgroup region.
A Molecular Dynamics Simulation Study of Two Dipeptide Based Molecular Micelles: Effect of Amino Acid Order  [PDF]
Kevin F. Morris, Eugene J. Billiot, Fereshteh H. Billiot, Kenny B. Lipkowitz, William M. Southerland, Yayin Fang
Open Journal of Physical Chemistry (OJPC) , 2013, DOI: 10.4236/ojpc.2013.31004
Abstract:

Molecular dynamics (MD) simulations were used to compare the structures of the chiral molecular micelles (MM) poly-(sodium undecyl-(L,L)-leucine-valine) (poly(SULV)) and poly-(sodium undecyl-(L,L)-valine-leucine) (poly (SUVL)). Both MM contained polymerized surfactant monomers terminated by chiral dipeptide headgroups. The study was undertaken to investigate why poly(SULV) is generally a better chiral selector compared to poly(SUVL) in electrokinetic chromatography separations. When comparing poly(SULV) to poly(SUVL), poly(SULV) had the more conformational flexible dipeptide headgroup and hydrogen bond analyses revealed that the poly(SULV) headgroup conformation allowed a larger number of intramolecular hydrogen bonds to form between monomer chains. In addition, a larger number of water molecules surrounded the chiral centers of the poly(SULV) molecular micelle. Poly(SULV) was also found to have a larger solvent accessible surface area (SASA) than poly(SUVL) and fluctuations in the poly(SULV) SASA during the MD simulation allowed dynamic monomer chain motions expected to be important in chiral recognition to be identified. Finally, approximately 50% of the Na+ counterions were found in the first three solvation shells surrounding both MM, with the remainder located in the bulk. Overall the MD simulations point to both greater headgroup flexibility and solvent and analyte access to the chiral centers of the dipeptide headgroup as factors contributing to the enhanced chiral selectivity observed with poly(SULV).

Effect of Surfactant Concentration on Aqueous LiBr Solution Absorption Rate  [PDF]
Ahmed F. Elsafty
Open Journal of Physical Chemistry (OJPC) , 2013, DOI: 10.4236/ojpc.2013.31001
Abstract:

It is well known that small amounts of surfactants, such as 1-Octanol, in the aqueous solution can increase the absorption rate significantly. In this paper, experimental data were obtained for absorption of water vapour into an aqueous LiBr solution with different concentrations of 1-Octanol. An experimental rig was specifically designed and developed in this work in order to investigate the effect of surfactant (1-Octanol) on the enhancement of the heat and mass transfer in the absorption process, in addition to, the investigation of the impact of the use of magnetic stirrer inside the absorber. The experimental rig for this study was based on the refrigeration mode of the intermittent vapour absorption system. In order to study the heat and mass transfer in water-lithium bromide vapour absorption air conditioning systems, it was necessary to monitor the concentration of the solution continuously. As a consequence, two procedures for obtaining the LiBr solution concentration were used. The first method was based on the measurement of the density and temperature of the solution, while the second was based on its electrolyte conductivity and the temperature. The experimental results showed that the surfactant concentration has a significant effect on the absorption rate; this is called the Marangoni instability. It has been concluded that, in order to clarify the absorption enhancement phenomenon, it is necessary to understand the physicochemical aspects of the absorption process and the effect of surfactants on the enhancement of such process. Additionally, it has been concluded that new approaches are needed to explain the observed behaviour.

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