Effect Of Surfactant Treatment Research Articles

Phytoremediation potential of Azolla filiculoides for sodium dodecyl benzene sulfonate (SDBS) surfactant considering some physiological responses, effects of operational parameters and biodegradation of surfactant.

In this study, phytoremediation potential of the Azolla filiculoides Lam. was examined for sodium dodecyl benzene sulfonate (SDBS) anionic surfactant. Furthermore, the effect of surfactant treatment on some physiological characteristics of Azolla was studied. The surfactant bioremoval efficiency was studied under variable conditions including treatment time, initial surfactant concentration, Azolla fresh weight, temperature, and pH. Results showed that surfactant removal efficiency of A. filiculoides was significantly enhanced with increasing of temperature, initial surfactant concentration, and amount of Azolla. SDBS led to a reduction in growth rate and total chlorophyll content, but effect index of Azolla increased by higher concentrations of surfactant. In contrast, antioxidant enzymes activities including polyphenol oxidase, ascorbate peroxidase, catalase, and peroxidase, as well as nonenzymatic antioxidants such as total carotenoids and anthocyanin contents significantly increased probably due to the ability of plant to overcome oxidative stress induced by SDBS. An increase in antioxidant activity based on 2, 2-diphenyl-1-picrylhydrazil (DPPH) confirmed this fact. An increase in the amount of hydrogen peroxide and reduction in membrane stability index indicated the induction of oxidative stress. As a result of SDBS biodegradation, 6 homologs of sulfophenyl carboxylates (SPCs) including C2 to C7-SPC and benzenesulfonate ring were identified by liquid chromatography-mass spectroscopy (LC-MS) analysis.

Effects of surfactant treatment in late preterm infants with respiratory distress syndrome

Objective: To evaluate surfactant effectiveness for the treatment of respiratory distress syndrome (RDS) in late preterm infants.Methods: We performed a retrospective cohort study of infants born between 34+0 and 36+6 weeks of gestation admitted for respiratory failure in seven perinatal centers from January 2010 to December 2014. We evaluated changes of FiO2, PaO2 and a/APO2 in surfactant-treated patients, and the need and duration of MV, the duration of noninvasive respiratory support, stay in NICU and in hospital in surfactant-treated and untreated late preterm infants with RDS alone.Results: We studied 562 infants with RDS, 252 (45%) were treated with surfactant and 310 (55%) were not. FiO2, PaO2 and a/APO2 significantly improved after surfactant treatment. The adjusted odds ratio for the need of MV and the adjusted differences of duration of noninvasive respiratory support, and of NICU and hospital stay were not different in the surfactant and non-surfactant groups.Conclusions: Surfactant therapy was followed by a quick and persisting significant improvement of respiratory function in late preterm infants with RDS. Surfactant did not improve short-term outcomes in our population probably because other factors such as the gestational age, occurrence of complications and poor feeding play a relevant role.

Effects of surfactant treatment on mechanical and microwave absorbing properties of graphene nanosheets/multiwalled carbon nanotubes/cyanate ester composites

Graphene nanosheets (GNSs) and multiwalled carbon nanotubes (MWCNTs) were treated with a nonionic surfactant polyvinylpyrrolidone (PVP), and its effects on dispersion state, surface chemistry, structure, and morphology of MWCNTs and GNSs, as well as on the microwave absorbing properties, mechanical properties of GNSs/MWCNTs/cyanate ester nanocomposites were analyzed respectively. Results show that surfactant plays an important role in dispersing the GNSs and MWCNTs in a solvent and polymer. The mechanical properties, such as impact fracture toughness and flexural strength all showed significant improvements after the treatment. The above observations are attributed to the unique amphiphile structures of PVP, which improved the interface characteristic between matrix and the fillers. Besides, PVP can effectively enhance interfacial interactions which gave rise to improved dispersion and wetting of GNSs and MWCNTs in polymer matrix. Unlike chemical functionalization techniques, however, the surfactant treatment exhibited little adverse effect on microwave absorption properties of the nanocomposite. POLYM. COMPOS., 39:110–118, 2018. © 2016 Society of Plastics Engineers

Surfactant-Assisted Dispersion of MWCNTs in Epoxy Resin Used in CFRP Strengthening Systems

The epoxy resin used as the bonding agent in carbon fiber-reinforced polymer (CFRP) strengthening systems was modified by the infusion of multiwalled carbon nanotubes (MWCNTs). Two types of surfactants, Triton X-100 and C12E8, were used to disperse the nanotubes in the epoxy resin employing ultrasonic mixing. Dynamic mechanical analysis and tensile tests were conducted to study the effect of the surfactant-assisted dispersion of nanotubes on the thermal and mechanical properties of epoxy composites. The morphology of the epoxy composites was interpreted using scanning electron microscopy (SEM). Moreover, the effect of surfactant treatment on the structure of nanotubes was investigated by Fourier transform infrared (FT-IR). Based on the experimental results, the tensile strength and the storage modulus of the epoxy resin were increased by 32% and 26%, respectively, by the addition of MWCNTs. This was attributed to the homogeneous dispersion of nanotubes in the epoxy resin according to the SEM images. Another reason for the enhancement in the tensile properties was the reinforced nanotube/epoxy interaction as a result of the surfactant anchoring effect which was proved by FT-IR. A moderate improvement in the glass transition temperature (T g) was recorded for the composite fabricated using Triton X-100, which was due to the restricted molecular motions in the epoxy matrix. To characterize the temperature-dependent tensile behavior of the modified epoxy composites, tensile tests were conducted at elevated temperatures. It was revealed that the MWCNT modification using surfactant substantially improves the tensile performance of the epoxy adhesive at temperatures above the T g of the neat epoxy.

Effect of surfactant treatment on thermal stability and mechanical properties of CNT/polybenzoxazine nanocomposites

Abstract The mechanical and thermo-mechanical properties of polybenzoxazine nanocomposites containing multi-walled carbon nanotubes (MWCNTs) functionalized with surfactant are studied. The results are specifically compared with the corresponding properties of epoxy-based nanocomposites. The CNTs bring about significant improvements in flexural strength, flexural modulus, storage modulus and glass transition temperature, Tg, of CNT/polybenzoxazine nanocomposites at the expense of impact fracture toughness. The surfactant treatment has a beneficial effect on the improvement of these properties, except the impact toughness, through enhanced CNT dispersion and interfacial interaction. The former four properties are in general higher for the CNT/polybenzoxazine nanocomposites than the epoxy counterparts, and vice versa for the impact toughness. The addition of CNTs has an ameliorating effect of lowering the coefficient of thermal expansion (CTE) of polybenzoxazine nanocomposites in both the regions below and above Tg, whereas the reverse is true for the epoxy nanocomposites. This observation has a particular implication of exploiting the CNT/polybenzoxazine nanocomposites in applications requiring low shrinkage and accurate dimensional control.

Effects of surfactant treatment on mechanical and electrical properties of CNT/epoxy nanocomposites

Surfactant has been successfully applied to enhance the dispersion of carbon nanotubes (CNTs) in polymer and the properties of nanocomposite. CNTs were treated with a nonionic surfactant Triton X-100, and its effects on dispersion state, surface chemistry, structure and morphology of CNTs, as well as on the thermomechanical, mechanical and electrical properties of CNT/epoxy nanocomposites were evaluated. The mechanical properties such as impact fracture toughness, flexural strength and modulus, the thermomechanical properties, as well as the electrical conductivity of the nanocomposite all showed significant improvements after the treatment. The above observations are attributed to the “bridging” effects between the CNT and epoxy, which are introduced by the hydrophobic and hydrophilic segments of the nonionic surfactant. The enhanced interfacial interactions gave rise to improved dispersion and wetting of CNTs in polymer matrix, enhancing the mechanical and fracture properties of the nanocomposite. Unlike chemical functionalization techniques, however, the surfactant treatment exhibited little adverse effect on electrical conducting behavior of the nanocomposite.

Effects of surfactant treatments on the wettability of a water repellent grass-covered dune sand

The objective of this study was to evaluate the effectiveness of the surfactant formulation Primer®604 for amelioration and management of soil water repellency in grass-covered dune sand. The soil is severely to extremely water repellent to a depth of >0.50 m during dry periods. Primer®604 was applied 12 times between 22 April and 23 November 1999. During that period, soil samples were taken in the untreated and treated plot—8 times in transects and 2 times in soil blocks. A total of 4950 samples were collected for assessment of the actual water repellency and for the spatial and temporal variability of the water content of the soil. Resistance to wetting was determined by measuring the wetting rate of field-moist samples. Measurements of water repellency revealed that applications of Primer®604 resulted in less persistent water repellency in the surface layer to a depth of 0.05 m. No effects were observed deeper in the soil profile, likely due to adsorption of the surfactant material in the surface layer. In the surface layer (0–0.025 and 0.025–0.05 m), the critical soil water content below which the soil is actually water repellent in the field was lowered distinctly by the application of Primer®604, potentially due to coating of water repellent particle surfaces by the surfactant. This suggests that the surface layer (0–0.05 m) in the Primer®604-treated soil can dry to lower water contents than in the untreated soil before water repellency is induced. The thatch layer (0–0.025 m) of the treated soil was often found to have slightly higher water contents than of the untreated soil. The surfactant did not equalise the uneven moisture distribution in the soil below the surface layer (0–0.05 m). Primer®604 applications increased the wetting rate of field-moist samples from the thatch layer. This may result in a more effective wetting of the root-zone during rain events or irrigation, and a reduction in runoff.

Influence of surfactants treatment on silver powder and its thick films

Thick film pastes have very high viscosities to retain the particles in suspension. The effects of surfactant treatment and the particle size of the silver powder on the screen printability (i.e. rheology, thixotropy, etc) and sintering of silver conductor paste have been investigated in this study. The variation in the rheology and sintering microstructure has been found to depend upon the type of surfactant treatment of the powders and their particle size. The paste prepared from silver powder treated with triethanolamine and caprylic acid exhibited a pseudoplastic flow and also demonstrated good screenability and better densification in both dried films as well as fired films as compared to those not treated with surfactants. The prepared powders consist of either separated particles or loose agglomerates, which get wetted and dispersed by the organic vehicle, forming a suspension displaying pseudoplastic behaviour. The powders with nanoscale size (100–200 nm) can be considered appropriate for effective thick film applications. Microstructure evolution after firing at 850 °C has been studied by examining the morphology and sheet resistance of the thick films.

Acute lung injury and lung transplantation influence in vitro subtype conversion of pulmonary surfactant.

The effects of surfactant treatment on surfactant subtype conversion after lung injury were examined. Dogs were subjected to hyperventilation for 8 h with or without surfactant treatment. Lungs were stored for 17 h, and the right lung was transplanted and reperfused for 6 h. Conversion of large aggregate (LA) surfactant to small aggregates was investigated using in vitro surface area cycling. LA from transplanted lungs (Transplant-LA) from the nontreated group converted more rapidly than Transplant-LA from the treated group. Transplant-LA from both groups converted more rapidly than LA from normal lungs. Calculations based on [(3)H]dipalmitoylphosphatidylcholine in the administered surfactant [bovine lipid extract surfactant (BLES)] showed that the endogenous component of Transplant-LA converted more rapidly than the exogenous component. This indicates exogenous BLES did not equilibrate completely with endogenous surfactant. LA from hyperventilated, stored donor right lungs and from the recipients' native lungs from the nontreated group converted more rapidly than corresponding LA in the BLES-treated group. Similar relative conversions were observed with exogenous components from all lungs. Relative conversion of endogenous component from Transplant-LA was more rapid than that from LA from donor's stored right lung or from the recipient's native right lung. Low levels of phenylmethylsulfonyl fluoride inhibited conversion of Transplant-LA to a greater extent than normal LA. LA from all experimental groups had similar protein levels. These studies show acute lung injury, transplant, ischemia-reperfusion, and surfactant treatment have major effects on surfactant subtype integrity.

Catalytic Liquefaction of Coal with Highly Dispersed Fe2S3 Impregnated in-Situ

Daliuta subbituminous coal, from Shenfu, Shanxi province of China, was liquefied in a 50 mL micro-autoclave apparatus at 440 °C, initial hydrogen pressure of 6.0 MPa, soaking time of 30 min, using a mixture of tetralin and cyclohexane as solvent. The experiments were carried out to investigate the effects of in-situ impregnated Fe2S3 on the liquefaction conversion, oil and gas yields of the coal, and the aromatic, aliphatic, and polar compounds fraction content in the oil. The effect of surfactant treatment during catalyst impregnation was also studied using hexadecyl-trimethylammonium bromide. Gradient elution chromatography (GEC), GC, and GC-MS were used to characterize and quantify the coal liquids. XRD and TEM were used to characterize the catalyst. The results indicate that without catalyst the conversion and oil yield are 43.2 and 37.4 wt %, respectively. At the same reaction condition but with the addition of 1.0 wt % Fe (based on daf coal), the conversion and oil yield reach 62.6 and 54.2 wt %, respectively. When the surfactant was used during the 1 wt % Fe catalyst impregnation, the conversion and oil yield became 68.8 and 59.5 wt %, respectively. The catalyst is dispersed in nanometer size particles in amorphous phase that transforms to pyrrholite phase during the liquefaction. The addition of 9.2 × 10-4 M surfactant changes the ζ-potential of the coal particles from −15 mV to +29 mV, decreases the size of catalyst particle on the coal surface from 30−40 to 15−20 nm. The oil products are complex aromatics with 2 to 3 rings.

Effects of surfactant treatment on gas-exchange and clinical course in near-term newborns with RDS.

To determine if there is a relationship between acute improvement in pulmonary gas exchange and surfactant use in near-term (35-39 weeks' gestation) infants with respiratory distress syndrome (RDS). We examined retrospectively the records of 54 infants admitted during a 15 month period who were 35 or more weeks of gestation, and who demonstrated all the diagnostic features of RDS. Data analyzed included: birth weight; gestational age; Apgar scores; calculated alveolar to arterial oxygen gradient (AaDO2) and oxygenation index (0I); hours of life at intubation; surfactant administration; complications with surfactant administration; use of inotropic medications. A total of 30 of infants were treated with intubation and surfactant administration. Mean FiO2 at the time of surfactant administration was 0.96. The AaDO2 decreased from 64.0 +/- 14.8 kPa to 41.8 +/- 22.5 kPa by 6 hrs (p < 0.0001). There was no relationship between age at treatment (6-89 hr) and response to treatment as measured by changes in AaDO2, FiO2, or oxygenation index (OI). Near-term infants with severe RDS often respond to exogenous surfactant, suggesting a functional deficiency of endogenous surfactant at a "late" stage in their disease process. We speculate that delayed treatment may still be effective in these patients.

Effects of Early Treatment with rSP-C Surfactant on Oxygenation and Histology in Rats with Acute Lung Injury

Surfactant treatment in patients with acute respiratory distress syndrome (ARDS) may be a promising treatment strategy. The aim of this study was to investigate whether addition of a recombinant surfactant protein C (rSP-C) to a plain phospholipid (PL) surfactant (PL surfactant) can result in activity comparable to commercially available surfactant preparations (Alveofact and bLES) which contain surfactant protein B and C. In this investigation dose–response comparisons of four surfactants were performed in an animal model of ARDS induced by total lung lavage. The surfactants were given shortly (10 min) after the last lavage. The effects of surfactant treatment were compared with respect to improve oxygenation and to prevent histopathological changes, such as hyaline membrane formation. The surfactants were compared to lavaged, untreated controls. The surfactants were administered at doses of 25, 50 and 100 mg total amount of phospholipids/kg body weight. At 120 min after early treatment, all three doses of rSP-C surfactant showed statistically significant higher improvements in oxygenation than PL surfactant. This improvement was comparable to bLES and superior to Alveofact. The rSP-C surfactant showed the most prominent effect on preventing hyaline membrane formation. It was again superior to PL surfactant and comparable to bLES. It is concluded that addition of rSP-C enhances the activity of a pure PL surfactant. The rSP-C surfactant showed comparable or even superior activity to bovine-derived surfactant preparations containing both, SP-B and SP-C.

Effect of Surfactant Treatment on Trends in Bronchopulmonary Dysplasia

Effect of Surfactant Treatment on Trends in Bronchopulmonary Dysplasia

Experimental neonatal respiratory failure induced by lysophosphatidylcholine: effect of surfactant treatment.

The purpose of this study was to characterize the toxic effects of lysophosphatidylcholine (lyso-PC) on neonatal lung function. Various doses of lyso-PC (from 0 to 40 mg/kg) were administered to near-term newborn rabbits. Lung-thorax compliance during mechanical ventilation was significantly decreased by doses >/=10 mg/kg, and static lung volumes during deflation were decreased by doses >/=20 mg/kg. Using the same experimental model, we investigated the effects of modified porcine surfactant (Curosurf, 200 mg/kg). Animals exposed to lyso-PC at birth and treated simultaneously with surfactant showed a satisfactory therapeutic response, whereas those treated after 30 min failed to respond. These animals also had a much larger leak of albumin into the air spaces and an elevated minimum surface tension of the lavage fluid in a pulsating bubble surfactometer, suggesting inactivation of the exogenous surfactant. Timing of surfactant administration may thus be essential for the therapeutic effect in this experimental model of acute lung injury.

Enhancement of Surfactant Effect by a Mechanical Volume Recruitment Maneuver Depends on the Lungs Preexisting Distension

‘Rescue’ surfactant treatment of premature infants with respiratory distress syndrome (RDS) results in two mechanisms: stabilization of alveoli already being ventilated and recruitment of alveoli collapsed before surfactant administration. Mechanical recruitment of alveoli from this collapsed compartment might enhance the immediate effects of surfactant treatment. To test this hypothesis 15 mechanically ventilated young rabbits underwent repeated airway lavage with normal saline at a constant, positive end-expiratory pressure (PEEP) of 3 cm H₂O until both the a/A ratio was <0.12 and a peak inspiratory pressure (PIP) >20 mbar was needed to keep the tidal volume (V_T) at 10 ml/kg. Surfactant (Survanta^®) was given over 4 min in conjunction with a mechanical volume recruitment maneuver (VRM) which consisted of an increased PIP by 33% of baseline values. The effects of surfactant were assessed using two indices of gas exchange (a/A ratio and PaCO₂), four indices of lung function (functional residual capacity, FRC, dynamic lung compliance, C_rs, V_T and the alveolar portion of V_T) and postmortem pressure-volume curves and were compared with two groups of rabbits receiving surfactant alone or no surfactant at all. VRM yielded an increase in C_rs by +22% whereas V_T increased by +58% suggesting overdistension of terminal airways to some extent. There were no differences between the surfactant and the VRM+surfactant groups for all indices assessed after an observational period of 2 h following surfactant administration. In a previous model using a PEEP of 1 cm H₂O [Krause et al., Am J Respir Crit Care Med 1997;156:862–866], significant differences have been disclosed for C_rs, V_T and FRC. In conclusion, the enhancement of surfactant effect by VRM largely depends on the preexisting distension of the lungs.

Rate of surfactant administration influences lung function and gas exchange in a surfactant‐deficient rabbit model

The aim of this study was to test whether the effect of surfactant treatment on lung function in a surfactant-deficient animal model can be influenced by the rate at which surfactant is administered. Surfactant deficiency was induced in 18 New Zealand white rabbits (weighing approx. 1 kg each) by lung lavage with normal saline. The arterial/alveolar oxygen ratio (a/A ratio), functional residual capacity (FRC), dynamic compliance of the respiratory system (Crs), tidal volume (VT), alveolar portion of the tidal volume (VA) and arterial PCO2 (Pa,CO2) were measured before and after lavage and 15, 30, 60, 90, and 120 min after administration of a single dose of surfactant (Survanta®, 100 mg/kg). Two surfactant administration protocols were compared over a 2-h interval: an infusion lasting 4 min and an infusion over 2 min. Both administrations were given during continuous mechanical ventilation. The six lung function and gas exchange parameters improved significantly following surfactant administration over 2 min compared with a control group. However, only the a/A ratio and VA improved following the 4-min protocol. Comparison of the two intervention protocols yielded significantly differences in VA and Pa,CO2, favoring the shorter administration. These results support the hypothesis that fast (2 min) administration of surfactant will improve its distribution to formerly collapsed alveoli and results in better lung function, improved ventilation, and (to a lesser extent) better oxygenation than prolonged infusions (4 min). Pediatr. Pulmonol. 1998; 25:196–204. © 1998 Wiley-Liss, Inc.

Effect of surfactant treatment on the formation of bound polymer on titanium dioxide powders

Effect of surfactant treatment on the formation of bound polymer on titanium dioxide powders

Surfactant treatment and ventilation effects on surfactant SP-A, SP-B, and SP-C mRNA levels in preterm lamb lungs

The effects of exogenous surfactant treatment combined with postnatal ventilation on surfactant protein (SP)-A, SP-B, and SP-C steady-state mRNA levels were evaluated in preterm sheep at 120, 132, and 139 days gestation. Three groups were studied at each gestation period: animals ventilated and treated with 100 mg/kg natural sheep surfactant, animals ventilated and not treated with surfactant, and a comparison group of lambs that were neither ventilated nor treated with surfactant. In unventilated lambs, SP-A and SP-C mRNA levels measured by densitometry from Northern blots increased between 120 and 132 days gestation (P < 0.05). At 120 days gestation, no differences in SP-A, SP-B, or SP-C mRNA levels were noted among the three groups. At 132 days gestation, SP-A mRNA levels increased in both ventilated groups (P < 0.01), but no additional surfactant effect on SP-A mRNA expression was detected. There were no changes in SP-B or SP-C mRNA levels among the groups at 132 days gestation. At 139 days gestation, mRNA levels for both SP-A and SP-B increased after ventilation, compared with the unventilated groups (P < 0.05). Furthermore, an additional effect of surfactant treatment to increase SP-A mRNA levels relative to animals undergoing ventilation alone was noted (P < 0.05). We conclude that postnatal changes in mRNA levels for the surfactant proteins are gestationally regulated and protein specific.

Effect of surfactant treatment on the formation of bound polymer on titanium dioxide powders

The dispersibility of agglomerates into polymeric media is affected by the interactions between the medium and the particles and between the particles themselves. In this work, we have used the amount of bound polymer as a measure of interfacial interactions between the particles and the medium. Titanium dioxide powders with surfaces modified with silica and/or alumina were analyzed for their interactions with various liquid media by suspending them in different solvents and monitoring dispersion stability for given periods of time. Applying the concept that materials which have cohesive energy densities in close range are compatible, data for the solubility parameters of liquids have been used to characterize the pigment surface. The adsorption of surfactants onto the particle surface will modify its characteristics, and consequently, the interfacial interactions with various media. Determination of the bound polymer in dispersions of different coated titania particles in linear low density poly(ethylene) showed better interactions between the polymer and the filler particles for surfactant treated powders.

Lung parenchyma and type II cell morphometrics: effect of surfactant treatment on preterm ventilated lamb lungs

The effect of exogenous surfactant treatment on lung and type II cell structure of ventilated lambs of 137-138 days gestational age was studied. Thirty-four lambs were delivered and randomized to control or 100 mg/kg of natural sheep surfactant treatment groups. Lungs from one group of lambs not treated with surfactant were fixed before ventilation, and the other animals were ventilated to maintain normal blood gas values for 3, 24, or 48 h. Morphometric assessment of the inflation-fixed lung parenchyma of ventilated lungs was compared with the architectural appearance of alveoli and alveolar ducts in the unventilated lungs. Mechanical ventilation resulted in distension of alveolar ducts accompanied by the shallowing and loss of well-defined alveoli and areas of atelectasis at 3 h. These abnormalities increased in severity after 24 and 48 h of ventilation. Surfactant treatment before ventilation significantly reduced the extent and degree of dilatation and concomitant atelectasis. The fraction of normal parenchyma was 38 +/- 7% in untreated lambs vs. 64 +/- 6% in treated lambs after 24 h of ventilation. After 48 h of ventilation, significant differences between control (39 +/- 6%) and surfactant-treated (55 +/- 6%) lambs were still evident. Alveolar type II cells contained approximately 15% lamellar bodies by volume. Neither surfactant treatment nor time of ventilation altered the volume density of lamellar bodies or other organelles, except for a decrease in glycogen from 8% in nonventilated lungs to 2.5% in lungs ventilated for 24 h. These findings indicate that a surfactant treatment at birth results in the maintenance of more normal parenchyma with less atelectasis during prolonged ventilation of the immature lung.(ABSTRACT TRUNCATED AT 250 WORDS)