Counter-Current Attrition Process (CCAP) to Remove Metals,Pentachlorophenol (PCP), Dioxins and Furans (PCDDF) from the 1-4-mm Fraction of Contaminated Soil

The objective of this study was to evaluate the potential of a counter-current attrition process (CCAP) over 15 cycles for removing metals, pentachlorophenol (PCP) and polychlorinated dibenzo-p-dioxins and -furans (PCDDF) from contaminated soil. The CCAP, applied to the 1–4-mm fraction of a contaminated soil, included five attrition steps (pulp density (PD) = 40% (w w^?1), surfactant [BW] = 2% (w w^?1), t = 20 min, T = 20°C) followed by one rinsing step. The water emerging from the first attrition step was treated using flocculation in the presence of 0.04 g CMX 123 (commercial flocculent) L^?1 before being reintroduced into the CCAP. The CCAP including the treatment of attrition wastewater (ATW) by flocculation achieved a removal of 44 ± 5% As, 26 ± 6% Cr, 24 ± 5% Cu, 49 ± 4% PCP and 45 ± 3% PCDDF. Moreover, the CCAP enabled a significant reduction (78%) in the amount of water required (around 14.5 m³ of water per ton of the 1–4-mm soil fraction). The high removal yields obtained after 15 attrition cycles of the CCAP for PCP and PCDDF and the significant reduction of water consumption confirm that this CCAP can be considered for industrial applications.     

Formation of model lipid bilayers at the silica-water interface by co-adsorption with non-ionic dodecyl maltoside surfactant

This present article describes a new and simple method for preparing model lipid bilayers. Stable and reproducible surface layers were produced at silica surfaces by co- adsorbing lipid with surfactant at the silica surface from mixed micellar solutions. The adsorption was followed in situ by use of ellipsometry. The mixed micellar solution consisted of a lipid (L-alpha-dioleoyllecithin) and a non-ionic sugar-based surfactant (n-dodecyl-beta-maltoside). The latter showed, by itself, no affinity for the surface and could, therefore, easily be rinsed off the surface after the adsorption step. By first adsorbing from solutions with high lipid and surfactant concentrations and then, in succession, rinsing and re-adsorbing from solutions with lower lipid-surfactant concentrations, a dense-packed lipid bilayer was produced at the silica surface. The same result can be achieved in a one-step process where the rinsing, after adsorption from the concentrated solution, is performed very slowly. The thickness of the adsorbed lecithin bilayer after this treatment found was to be about 44 +/- 3 A, having a mean refractive index of 1.480 +/- 0.004. The calculated surface excess of lipids on silica was about 4.2 mg m(-2), giving an average area per lipid molecule in the two layers of 62 +/- 3 A2. The physical characteristic of the adsorbed bilayer is in good agreement with previously reported data on bulk and surface supported lipid bilayers. However, in contrast to previous investigations, we found no support for the presence of a thicker multi-molecular water layer located between the lipid layer and the solid substrate.     

Influence of membrane viscosity on the lateral and transverse mobility of carboxylic ionophores

The rate of ⁴⁵Ca or ²²Na exchange-diffusion in multilamellar liposomes formed of dipalmitoyl-phosphatidycholine (DPPC) and cholesterol and containing the ionophore A23187 or Br-X537A was dramatically increased when the temperature and, hence, fluidity of the lipid bilayer were increased. In the case of ⁴⁵Ca transport, i.e. when each Ca²⁺ ion binds to two molecules of ionophore, the relative increment in transport velocity in response to a given increase in temperature or fluidity was much more marked in the high range of temperature (30–40°C) than in the low range of temperature (22–28°C). In the case of ²²Na transport, however, i.e. when each Na⁺ ion binds to only one ionophoretic molecule, the temperature-dependency of the transport process followed a single pattern throughout the entire range of temperature. In the latter case, the slope of the temperature-dependent line was the same as that seen for ⁴⁵Ca transport by the same ionophore at high temperatures. A decrease in the ionophore content of the liposomes shifted to a higher temperature the transition point between the flat and steep lines characterizing the temperature dependency of ⁴⁵Ca transport. It is concluded that the membrane viscosity affects both the lateral mobility of the ionophoretic molecules and the transverse mobility of the cation-ionophore complex.     

Kinetics of microbial death by combined treatment with heat and antimicrobial agents

Studies were made of the death kinetics of Escherichia coli cells heated at 46 to 56°C in 0.05M phosphate buffer (pH 7.0) containing either an amphoteric surfactant (Tego 15DL, 1–10 μg/ml) or sorbic acid (0.5 to 3%). A linear relationship was obtained on the Arrhenius plot for the death of cells heated with each antimicrobial agent. The kinetics of the action of the surfactant, however, differed from that of sorbic acid. With the amphoteric surfactant, the activation enthalpy of the death reaction decreased from 108 to 51 kcal/mol as the concentration of surfactant was increased in the range tested although the death rate remained high; whereas with sorbic acid the activation enthalpy remained fairly constant (104 ± 9 kcal/mol) independent of its concentration and the death rate was similarly high. Further, in the action of the amphoteric surfactant, a thermodynamic compensation effect was observed, the compensation temperature being 334°K (61°C), i.e., relatively close to the observed temperatures. For sorbic acid, however, this temperature seemed to be too high to observe when determined from the Arrhenius plot. The data of the dependency of the death-rate constant upon the concentration of antimicrobial agent indicated a similar difference in the action of the two agents. Based on our results and on data obtained by other workers, we propose that antimicrobial agents that enhance cellular death induced by heating can be characterized into two types.     

The effects of different blend ratios and temperature on the active space of the Oriental fruit moth sex pheromone

Abstract The wing-fanning activation response of male Oriental fruit moths (OFM), Grapholita molesta (Busck), in the field to the three-component pheromone containing the female-produced ratio of components (Z8-12:OAc + 6% E8-12:OAc + 3% Z8-12:OH) was compared with the response to blends containing 2,10 and 20% E with 3% OH, and the 6% E blend containing 30 and 100% OH. Comparisons were made over three temperature ranges: 15–17, 20–21 and 26–28^oC. Both the maximum response distance and male response specificity were significantly altered by changes in odour quality as well as temperature. For blends containing different Z/E ratios the maximum response distance increased significantly with temperature. Response specificity was most pronounced at the 20–21^oC range, with males displaying a lower threshold for the natural 6% E ratio, evidenced by the fact that fewer males responded and at closer distances to the source with off-ratios. At 26–28^oC response specificity for the Z/E ratios was much reduced, primarily due to more males activating to off-ratios. With blends containing different proportions of Z8-12:OH in the 6% E blend, increasing temperature increased the maximum response distance for all treatments, but in addition increasing the proportion of OH alone from 3% to 30% significantly increased the maximum response distance over the three temperature ranges tested. This increase occurred without affecting the proportion of responders or the distribution of response distances around the mean value. However, with 100% OH added to the blend, whereas male response was high at 20–21^oC, the distribution of response distances was significantly more variable than with 3% or 30%, and male response was eliminated or very low at 15–17^oC and 26–28^oC. Our results support previous studies showing that peak response levels in this species are dependent on male perception of the natural blend of components, and that males have a high degree of specificity for the qualitative properties of the pheromone. However, the present results also extend those of previous flight tunnel tests in which response specificity was most pronounced in the upwind flight phase of the sequence, by showing that male OFM also display a     

CuS Microspheres with Tunable Interlayer Space and Micropore as a High‐Rate and Long‐Life Anode for Sodium‐Ion Batteries

Layered transition metal sulfides (LTMSs) have tremendous commercial potential in anode materials for sodium‐ion batteries (SIBs) in large‐scale energy storage application. However, it is a great challenge for most LTMS electrodes to have long cycling life and high‐rate capability due to their larger volume expansion and the formation of soluble polysulfide intermediates caused by the conversion reaction. Herein, layered CuS microspheres with tunable interlayer space and pore volumes are reported through a cost‐effective interaction method using a cationic surfactant of cetyltrimethyl ammonium bromide (CTAB). The CuS–CTAB microsphere as an anode for SIBs reveals a high reversible capacity of 684.6 mAh g^?1 at 0.1 A g^?1, and 312.5 mAh g^?1 at 10 A g^?1 after 1000 cycles with high capacity retention of 90.6%. The excellent electrochemical performance is attributed to the unique structure of this material, and a high pseudocapacitive contribution ensures its high‐rate performance. Moreover, in situ X‐ray diffraction is applied to investigate their sodium storage mechanism. It is found that the long chain CTAB in the CuS provides buffer space, traps polysulfides, and restrains the further growth of Cu particles during the conversion reaction process that ensure the long cycling stability and high reversibility of the electrode material.     

Formation of supported phospholipid bilayers via co-adsorption with β-d-dodecyl maltoside

We have investigated the formation of supported model membranes via the adsorption of phospholipid-surfactant mixtures at the Si-water interface by specular neutron reflection. The adsorption of mixed micelles of the nonionic surfactant β-d-dodecyl maltoside and DOPC or POPC was determined as a function of bulk concentration, and using d₂₅-β-d-dodecyl maltoside, the composition of DOPC and POPC bilayers was determined. Bilayer thicknesses of 39±3 Å for DOPC and 41±3 Å for POPC agree well with data from bulk lamellar phases for both lipids, and the average area per lipid molecule can be varied from 62 to 115 Ų by varying the bulk concentrations used. The amount of surfactant in the bilayer is very sensitive to the bulk volume-to-surface area ratio, but it can be fully eliminated by ensuring a sufficiently large dilution/rinsing volume of the solution.     

Conformational and phase transitions in DNA—photosensitive surfactant solutions: Experiment and modeling

DNA binding to trans‐ and cis‐isomers of azobenzene containing cationic surfactant in 5 mM NaCl solution was investigated by the methods of dynamic light scattering (DLS), low‐gradient viscometry (LGV), atomic force microscopy (AFM), circular dichroism (CD), gel electrophoresis (GE), flow birefringence (FB), UV–Vis spectrophotometry. Light‐responsive conformational transitions of DNA in complex with photosensitive surfactant, changes in DNA optical anisotropy and persistent length, phase transition of DNA into nanoparticles induced by high surfactant concentration, as well as transformation of surfactant conformation under its binding to macromolecule were studied. Computer simulations of micelles formation for cis‐ and trans‐isomers of azobenzene containing surfactant, as well as DNA‐surfactant interaction, were carried out. Phase diagram for DNA‐surfactant solutions was designed. The possibility to reverse the DNA packaging induced by surfactant binding with the dilution and light irradiation was shown. © 2014 Wiley Periodicals, Inc. Biopolymers 103: 109–122, 2015.     

Helix–coil stability constants for the naturally occurring amino acids in water. XXI. Glutamine parameters from random poly(hydroxypropylglutamine-co-L-glutamine) and poly(hydroxybutylglutamine-co-L-glutamine)

Water-soluble, random copolymers containing L -glutamine and either N⁵-(3-hydroxypropyl)-L -glutamine or N⁵-(4-hydroxybutyl)-L -glutamine were synthesized, fractionated, and characterized. The thermally induced helix–coil transitions of these copolymers were studied in water. A short-range interaction theory was used to deduce the Zimm-Bragg parameters σ and s for the helix–coil transition in poly(L -glutamine) in water from an analysis of the melting curves of the copolymers in the manner described in earlier papers. The computed values of s indicate that L -glutamine is helix-indifferent at low temperature and a helix-destabilizing residue at high temperature in water. At all temperatures in the range of 0–70°C, the glutamine residue promotes helix–coil boundaries since the computed value of σ is large.     

Interaction of the C-Terminal Peptide of Pulmonary Surfactant Protein B (SP-B) with a Bicellar Lipid Mixture Containing Anionic Lipid

The hydrophobic lung surfactant SP-B is essential for respiration. SP-B promotes spreading and adsorption of surfactant at the alveolar air-water interface and may facilitate connections between the surface layer and underlying lamellar reservoirs of surfactant material. SP-B_63–78 is a cationic and amphipathic helical peptide containing the C-terminal helix of SP-B. ²H NMR has been used to examine the effect of SP-B_63–78 on the phase behavior and dynamics of bicellar lipid dispersions containing the longer chain phospholipids DMPC-d ₅₄ and DMPG and the shorter chain lipid DHPC mixed with a 3∶1∶1 molar ratio. Below the gel-to-liquid crystal phase transition temperature of the longer chain components, bicellar mixtures form small, rapidly reorienting disk-like particles with shorter chain lipid components predominantly found around the highly curved particle edges. With increasing temperature, the particles coalesce into larger magnetically-oriented structures and then into more extended lamellar phases. The susceptibility of bicellar particles to coalescence and large scale reorganization makes them an interesting platform in which to study peptide-induced interactions between lipid assemblies. SP-B_63–78 is found to lower the temperature at which the orientable phase transforms to the more extended lamellar phase. The peptide also changes the spectrum of motions contributing to quadrupole echo decay in the lamellar phase. The way in which the peptide alters interactions between bilayered micelle structures may provide some insight into some aspects of the role of full-length SP-B in maintaining a functional surfactant layer in lungs.     

Continuous alcohol production from starchy materials with a novel immobilized cell/enzyme bioreactor

In a novel bioreactor system that was packed with both Al alginate biocatalyst A (entrapment of adsorbed-glucoamylase on γ-alumina) and biocatalyst B (entrapment of a mixture of different strains of yeast cells), 60–95 kg/m³ of alcohol solution were continuously produced through parallel operation of saccharifying and fermenting liquefied starchy materials of potato and grains without contamination. This continuous process was anaerobically performed at a pH of 2.8–3.2 and a temperature of 30°C.     

Dispersal of Septoria nodorum Pycnidiospores by Simulated Raindrops in Still Air

Simulated raindrops, diameter c. 3 or 4 mm, fell 13 m down a raintower onto suspensions of Septoria nodorum pycnidiospores, depth 0.5 mm, or infected straw pieces. Splash droplets were collected on pieces of fixed photographic film. It was estimated that one drop generated c. 300 spore carrying splash droplets, containing c. 6000 spores, from a concentrated spore suspension (6.5 × 10⁵ spores/ml) and c. 25 spore-carrying droplets, containing c. 30 spores, from infected straw pieces (11 × 10⁶ spores/g dry wt). When the target was a spore suspension in water without surfactant, most spore-carrying droplets were in the 200—400 μm size category and most spores were carried in droplets with diameter >1000 μm. When surfactant was added to spore suspensions, most spore-carrying droplets were in the 0–200 μm category and most spores were carried in droplets with diameter 200–400 μm and none in droplets >1000 μm. Regression analyses showed a significant (p < 0.001) relationship between square root (number of spores per droplet) and droplet diameter; the slope of the regression line was greatest when surfactant was added to the spore suspensions. The distribution of splash droplets with distance travelled from the target was better fitted by an exponential model than by power law or Gaussian models. The distributions of spore-carrying droplets and spores with distance were fitted better by an exponential model than by a power law model. Thus regressions of log, (number collected) against distance were all significant (p < 0.01); the slopes of the regression lines were steepest when surfactant was added to the spore suspension. At a distance of 10 cm from target spore suspensions most splash droplets and spore-carrying droplets were collected at height 10–20 cm, with none above 40 cm; at a distance of 20 cm there were most at heights 0–10 cm and 40–50 cm.     

Reducing the microcapsule diameter by micro-emulsion to improve the insecticidal activity of Bacillus thuringiensis encapsulated formulations

The emulsion/internal gelation method is highly effective to produce microcapsules of Bacillus thuringiensis (Bt) in a short time; however, it has the limitation to produce microcapsules within a wide range of diameters (1–1000?µm). The aim of this study was to reduce the range of small microcapsule diameters by using a water/corn-oil (W/CO) micro-emulsion as the dispersing medium and the mixture Tween 80–Span 80 as the surfactant. It involved the development of the W/CO micro-emulsion and the determination of the suitable agitation time to disperse the gelling medium (sodium alginate) through the micro-emulsion. A micro-emulsion formulation that allowed reduction of the microcapsule diameter was composed of 82% corn oil, 12% alginate solution and 6% surfactant mixture Tween80–Span80 (31:69). Evaluation of four dispersing times showed that 45 min was suitable to produce 75% of microcapsules of an average diameter of 3.1?±?1?µm containing the spore–protein complex (SPC) produced by Bt. Bioassays carried out at low concentrations of microencapsulated formulations of cry proteins allowed determination of how its insecticidal effect increased if the range of microcapsule diameters was reduced in the range 1–9?µm. Furthermore, the SPC formulation in alginate microcapsules showed high resistance to extreme irradiation (2.9?±?0.5?×?10⁸ erg) of a long wavelength (365?nm), which made the microencapsulated formulation profitable and of high yield since repeated applications of the biopesticide during the same harvest period may not be necessary.     

Investigation of aerobic degradation kinetics of surfactants using respirometric batch experiments

The mineralization of a non-ionic alcohol ethoxylate (AEO) surfactant was investigated over the concentration range occurring in rinsing water from surfactant production processes. For this, an experimental set-up for respirometric batch experiments was developed. The set-up and the method were validated by experiments with glucose as the single carbon source. It was possible to calculate substrate decay from the time course of exogenously consumed oxygen during respirometric batch experiments. The kinetic coefficients calculated by respirometry showed a lower standard deviation than those calculated from emasured glucose concentrations. The degradation mechanism of AEO was investigated by identification of metabolities, occurring during the mineralization process of AEO, using Flow Injection Mass spectrometry (FI-MS). It was concluded that the degradation of AEO occurs in two main steps. First, the enzymatic hydrolysis of AEO into alcohol and polythylene glycol (PEG) is performed. Second, the mineralization of both substances takes place, while the mineralization of the alcohol is faster than that of the PEG. The mineralization kinetics were investigated in respirometric batch experiments. The model used is based on double MONOD kinetics for the substrates being produced by hydrolysis (μ_max1 = 0.047 h^?1, K_s1 = 15 mg/l DOC for alcohol; μ_max2 = 0.027 h^?1, K_S2 = 4 mg/l DOC for PEG). The validation of the model by calculating the results obtained from measurements in a continuously operated lab scale CSTR with bacteria recycle was successful.     

Biosynthesis of sucrose-6-acetate catalyzed by surfactant-coated Candida rugosa lipase immobilized on sol–gel supports

Sucrose-6-acetate is an important intermediate in the preparation of sucralose (a finest sweetener). In our study, Candida rugosa lipase coated with surfactant was firstly immobilized on sol–gel supports. Then, the immobilized enzyme was used in the regioselective synthesis of sucrose-6-acetate by transesterification of sucrose and vinyl acetate. The screening results revealed that Tween 80 was an ideal surfactant to coat lipase immobilized in sol–gel and exhibited the highest yield of sucrose-6-acetate. Other factors that influenced the yield during the preparation process were also studied. Under optimal conditions, the yield of sucrose-6-acetate could reach up to 78.68 %, while free lipase was easily inactivated in polar solvent. Thermal and operational stabilities were also improved significantly. Surfactant-coated lipase immobilized in sol–gel remained stable when the temperature was higher than 60 °C. Moreover, they could maintain high catalytic activity after six recycles. This strategy is economical, convenient and promising for the food industry.     

A downstream process with microemulsion extraction for microbial transformation in cloud point system

A downstream process strategy for a whole microbial transformation to produce l-phenylacetylcarbinol (PAC) in a nonionic surfactant Triton X mediated cloud point system was developed. By application of a Winsor I microemulsion, the product and the nonionic surfactant in the microbial transformation broth was separated successfully. Then the nonionic surfactant was recovered with a Winsor II microemulsion. In a single stage Winsor I microemulsion extraction process, the product recovery ratio 76.9% and the nonionic surfactant recovery ratio 66.5% were achieved. A discrete countercurrent extraction operation was also carried out to improve the separation efficiency. Finally, character of the recovery nonionic surfactant was also examined.     

Self-Nanoemulsifying Drug Delivery System of Nifedipine: Impact of Hydrophilic–Lipophilic Balance and Molecular Structure of Mixed Surfactants

A simple but novel mixed surfactant system was designed to fabricate a self-nanoemulsifying drug delivery system (SNEDDS) based on hydrophilic–lipophilic balance (HLB) value. The impacts of HLB and molecular structure of surfactants on the formation of SNEDDS were investigated. After screening various oils and surfactants, nifedipine (NDP)-loaded liquid SNEDDS was formulated with Imwitor^® 742 as oil and Tween^®/Span^® or Cremophor^®/Span^® as mixed surfactant. Droplet size of the emulsions obtained after dispersing SNEDDS containing Tween^®/Span^® in aqueous medium was independent of the HLB of a mixed surfactant. The use of the Cremophor^®/Span^® blend gave nanosized emulsion at higher HLB. The structure of the surfactant was found to influence the emulsion droplet size. Solid SNEDDS was then prepared by adsorbing NDP-loaded liquid SNEDDS comprising Cremophor^® RH40/Span^® 80 onto Aerosil^® 200 or Aerosil^® R972 as inert solid carrier. Solid SNEDDS formulations using higher amounts (30–50% w/w) of Aerosil^® 200 exhibited good flow properties with smooth surface and preserved the self-emulsifying properties of liquid SNEDDS. Differential scanning calorimetry and X-ray diffraction studies of solid SNEDDS revealed the transformation of the crystalline structure of NDP due to its molecular dispersion state. In vitro dissolution study demonstrated higher dissolution of NDP from solid SNEDDS compared with NDP powder.     

Production of surfactant by Arthrobacter paraffineus ATCC 19558

A. paraffineus ATCC 19558 grown in MMSM (modified mineral salts medium) containing hydrocarbon produced surfactant, with a maximum CMC(-1) value obtained by using hexadecane as the carbon source. No activity of surface active agent in whole broth was observed when glucose was used in the MMSM instead of hexadecane. The biomass concentration obtained with glucose was about 40% of that obtained with hexadecane. Glucose (4%) in the medium contaning hexadecane caused a 27 and 21% decrease of biomass and surfactant concentrations, respectively. In the process of surfactant production, glucose can be used as a carbon source for growth, and hexadecane added later can serve for production of the surface active agent. The optimum temperature for production of surfactant is 27 degrees C.     

Thermodynamics of interaction of octyl glucoside with phosphatidylcholine vesicles: partitioning and solubilization as studied by high sensitivity titration calorimetry

The interaction of the surfactant octyl glucoside (OG) with dimyristoylphosphatidylcholine (DMPC), dipalmitoylphosphatidylcholine (DPPC), distearoylphosphatidylcholine (DSPC), and soy bean phosphatidylcholine (soy bean PC) was studied using high-sensitivity titration calorimetry. We determined the partition coefficient of OG between water and lipid bilayers and the transfer enthalpy of the surfactant by addition of lipid vesicles to OG monomers or vice versa. Comparison with the micellization enthalpy of the surfactant gives information on differences in the hydrophobic environment of OG in a liquid-crystalline bilayer or a micelle. The average partition coefficient P in mole fraction units for x_e≈0.12–0.2 decreases slightly from 4152 at 27°C to 3479 at 70°C for DMPC and from 4260 to 3879 for soy bean PC, respectively. The transfer enthalpy ΔH^T of OG into lipid vesicles is positive at 27°C and negative at 70°C. Its temperature dependence is larger for the incorporation of OG into DMPC than into soy bean PC vesicles. It is concluded that OG in DMPC vesicles is better shielded from water than in soy bean PC vesicles or in micelles. Titration calorimetry was also used to determine the phase boundaries of the coexistence region of mixed vesicles and mixed micelles in the systems OG/DMPC, OG/DPPC, OG/DSPC, and OG/soy bean PC vesicles at 70°C in the liquid-crystalline phase. DMPC and soy bean PC solubilization was also studied at 27°C to investigate the effect of temperature. The effective surfactant to lipid ratios at saturation, R_e^sat, for all PCs studied are in the range between 1.33–1.72 and the ratios at complete solubilization, R_e^sol, are between 1.79–3.06. At 70°C, the R_e^sat values decrease with increasing chain length of the saturated PC. The ratios depend also slightly on temperature and the degree of unsaturation of the fatty acyl chains. For the OG/soy bean PC system, the coexistence range for mixed vesicles and mixed micelles is larger than for the corresponding PCs with saturated chains.     

Effects of palmitoylation on dynamics and phospholipid-bilayer-perturbing properties of the N-terminal segment of pulmonary surfactant protein SP-C as shown by 2H-NMR

It has been proposed that palmitoylation of the N-terminal segment of surfactant protein SP-C is important for maintaining association of pulmonary surfactant complexes with interfacial films compressed to high pressures at the end of expiration. In this study, we examined surfactant membrane models containing palmitoylated and nonpalmitoylated synthetic peptides, based on the N-terminal SP-C sequence, in dipalmitoylphosphatidylcholine (DPPC)/egg phosphatidylglycerol (7:3, w/w) by ²H-NMR. Perturbations of lipid properties by the peptide versions were compared in samples containing chain- and headgroup-deuterated lipid (DPPC-d₆₂ and DPPC-d₄ respectively). Also, deuterated peptide palmitate chains were compared with those of DPPC in otherwise identical lipid-protein mixtures. Palmitoylated peptide increased average DPPC-d₆₂ chain orientational order slightly, particularly for temperatures spanning gel and liquid crystalline coexistence, implying penetration of palmitoylated peptide into ordered membrane. In contrast, the nonpalmitoylated peptide had a small disordering effect in this temperature range. Both peptide versions perturbed DPPC-d₄ headgroup orientation similarly, suggesting little effect of palmitoylation on the largely electrostatic peptide-headgroup interaction. Deuterated acyl chains attached to the SP-C N-terminal segment displayed a qualitatively different distribution of chain order, and lower average order, than DPPC-d₆₂ in the same membranes. This likely reflects local perturbation of lipid headgroup spacing by the peptide portion interacting with the bilayer near the peptide palmitate chains. This study suggests that SP-C-attached acyl chains could be important for coupling of lipid and protein motions in surfactant bilayers and monolayers, especially in the context of ordered phospholipid structures such as those potentially formed during exhalation, when stabilization of the respiratory surface by surfactant is the most crucial.