Search results for "Surfactant"
showing 10 items of 397 documents
Liquid Phase Micro-Extraction of Linear Alkylbenzene Sulfonate Anionic Surfactants in Aqueous Samples
2011
Hollow fiber liquid phase micro-extraction (LPME) of linear alkylbenzene sulfonates (LAS) from aqueous samples was studied. Ion pair extraction of C10, C11, C12 and C13 homologues was facilitated with trihexylamine as ion-pairing agent, using di-n-hexylether as solvent for the supported liquid membrane (SLM). Effects of extraction time, acceptor buffer concentration, stirring speed, sample volume, NaCl and humic acids were studied. At 10–50 µg L−1 linear R2-coefficients were 0.99 for C10 and C11 and 0.96 for C12. RSD was typically ~15%. Three observations were especially made. Firstly, LPME for these analytes was unusually slow with maximum enrichment observed after 15–24 h (depending on sa…
MASS SPECTROMETRY IN THE STUDY OF PHOSPHATIDYLCHOLINE ADDUCTS
2008
Supramolecular surfactant aggregates in gas-phase:monocharged sodium alkanesulfonate clusters
2009
Dynamic tuning of the director field in liquid crystal shells using block copolymers
2020
When an orientationally ordered system, like a nematic liquid crystal (LC), is confined on a self-closing spherical shell, topological constraints arise with intriguing consequences that depend critically on how the LC is aligned in the shell. We demonstrate reversible dynamic tuning of the alignment, and thereby the topology, of nematic LC shells stabilized by the nonionic amphiphilic block copolymer Pluronic F127. Deep in the nematic phase, the director (the average molecule orientation) is tangential to the interface, but upon approaching the temperature TNI of the nematic– isotropic transition, the director realigns to normal. We link this to a delicate interplay between an interfacial …
Effects of ultrasonically activated irrigants with or without surfactant on smear layer removal after post space preparation
2012
The aim of this study was to compare the effects of different NaOCl and EDTA formulations with/without ultrasonic use on smear layer removal and root canal surface characteristics after post space preparation. Study design: After post space preparations, forty-six teeth were subjected to different post space irrigation regimes; G1, 17% EDTA; G2, 17% EDTA+Ultrasonic activation; G3, EDTA-T; G4, EDTA-T+Ultrasonic activation; G5, NaOCl; G6, NaOCl+Ultrasonic activation. Specimens were examined under scanning electron microscope and scored for debris and smear layer removal and dentinal tubule opening and statistically analyzed with Kruskal Wallis and Dunn's test. Significance value was set at p<…
Serum surfactant protein D is a potential biomarker of lung damage in systemic sclerosis
2016
Background: Interstitial lung disease (ILD) complicates the course of systemic sclerosis (SSc) up to two-third of the cases, representing the main cause of death in these patients. Assessment of lung involvement by HRCT and close monitoring of lung function are mandatory. At present no serologic biomarkers are validated for the assessment for lung damage in SSc. The current study was designed to test the hypothesis that the levels of surfactant are altered in SSc compared to healthy controls. To this aim serum levels of SP-A (Surfactant Protein A) and SP-D (Surfactant Protein-D) in serum were assessed. Methods: We enrolled 12 consecutive patients (M/F: 2/10) affected by scleroderma referred…
Supraglottic airway devices for surfactant treatment: systematic review and meta-analysis
2019
Objective: To compare surfactant administration via supraglottic airway device (SAD) vs. nasal CPAP alone or INSURE. Study design: A systematic search of PubMed, EMBASE, SCOPUS, Cochrane Central Register of Controlled Trials and Clinicaltrials.gov was performed. Articles meeting inclusion criteria (RCT, surfactant administration via SAD, laryngeal mask, I-gel) were assessed Results: Five RCTs were eligible. Surfactant administration via SAD reduced the need for intubation/mechanical ventilation (RR 0.57, 95%CI 0.38–0.85) and short-term oxygen requirements (MD −8.00, 95%CI −11.09 to −4.91) compared to nCPAP alone. Surfactant administration via SAD reduced the need for intubation/mechanical v…
Spatially ordered surfactant assemblies in the gas phase: negatively charged bis(2-ethylhexyl)sulfosuccinate- alkaline metal ion aggregates
2009
The formation and structural features of negatively charged aggregates of sodium bis(2-ethylhexyl)sulfosuccinate (AOTNa) surfactant molecules in the gas phase have been investigated by electrospray ionization mass spectrometry (ESI-MS) and density functional theory calculations. Mainly driven by the interactions of alkali metal ions both with the oxygen atoms of the sulfonate group and with the succinate moiety of the AOT(-) anion, spatially ordered supramolecular assemblies, characterized by an internal core composed of surfactant counterions and hydrophilic head groups surrounded by the surfactant alkyl chains pointing outwards, are formed. Calculations have shown that surfactant self-org…
Micelles in Mixtures of Sodium Dodecyl Sulfate and a Bolaform Surfactant
2006
Mixtures composed of water, sodium dodecyl sulfate (SDS), and a bolaform surfactant with two aza-crown ethers as polar headgroups (termed Bola C-16) were investigated by modulating the mole ratios between the components. The two surfactants have ionic and nonionic, but ionizable, headgroups, respectively. The ionization is due to the complexation of alkali ions by the aza-crown ether unit(s). Structural, thermodynamic, and transport properties of the above mixtures were investigated. Results from surface tension, translational self-diffusion, and small angle neutron scattering ( SANS) are reported and discussed. Interactions between the two surfactants to form mixed micelles result in a com…