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[Hypothesis] l-carnitines in our body systems can be readily converted into acyl-l-carnitines which have a prominent place in cellular energy generation by supporting the transport of long-chain fatty acids into mitochondria. As biocompatible surfactants, acyl-l-carnitines have potential to be useful in technical, personal care and healthcare applications. However, the lack of understanding of the effects of their molecular structures on their physical properties has constrained their potential use., [Experiments] This work reports the study of the influence of the acyl chain lengths of acyl-l-carnitines (CnLC) on solubility, surface adsorption and aggregation. Critical micellar concentrations (CMCs) of CnLC were determined by surface tension measurements. Neutron reflection (NR) was used to further examine the structure and composition of the adsorbed CnLC layer. The structural changes of the micellar aggregates under different concentrations of CnLC, pH and ionic strength were determined by dynamic light scattering (DLS) and small angle neutron scattering (SANS)., [Findings] C12LC is fully soluble over a wide temperature and concentration range. There is however a strong decline of solubility with increasing acyl chain length. The adsorption and aggregation behavior of C14LC was therefore studied at 30 °C and C16LC at 45 °C. The solubility boundaries displayed distinct hysteresis with respect to heating and cooling. The CMCs of C12LC, C14LC and C16LC at pH 7 were 1.1 ± 0.1, 0.10 ± 0.02 and 0.010 ± 0.005 mM, respectively, with the limiting values of the area per molecule at the CMC being 45.4 ± 2, 47.5 ± 2 and 48.8 ± 2 Å2 and the thicknesses of the adsorbed CnLC layers at the air/water interface increasing from 21.5 ± 2 to 22.6 ± 2 to 24.2 ± 2 Å, respectively. All three surfactants formed core–shell spherical micelles with comparable dimensional parameters apart from an increase in core radius with acyl chain length. This study outlines the effects of acyl chain length on the physicochemical properties of CnLCs under different environmental conditions, serving as a useful basis for developing their potential applications., We thank Lonza for funding this project under the grant number P121881. The provision of neutron beam time from ISIS Neutron Facility (LOQ, RB1920293 and Surf, RB1920156) and ILL Neutron Facility (D11, 9-10-1613 and FIGARO, 9-13-840) is acknowledged. We also appreciate the SasView, developed by NSF award DMR-0520547, and Igor pro.

The formation of surface multilayer structures, induced by the addition of multivalent counterions in dilute surfactant solutions, has been widely observed in a range of anionic surfactants. The phenomenon is associated with the ability to manipulate surface properties, especially in the promotion of enhanced surface wetting, and in the presence of an extensive near surface reservoir for rapid surface delivery of surfactant and other active components. Hypothesis. In the single alkyl chain anionic surfactants, such as sodium dodecysulfate, SDS, sodium alkylethoxylsulfate, SAES, and alkylestersulfonate, AES, surface multilayer formation is promoted by trivalent counterions such as Al3+, and is generally not observed with divalent counterions, such as Ca2+ or with monovalent counterions. In the di-alkyl chain anionic surfactant, dodecylbenzenesulfonate, LAS, surface multilayer formation now occurs in the presence of divalent counterions. It is attributed to the closer proximity of a bulk lamellar phase, resulting in a greater tendency for surface multilayer formation, and hence should occur in other di-alkyl chain anionic surfactants. Experiments. Aerosol-OT, AOT, is one of the most commonly used di-alkyl chain anionic surfactants, and is extensively used as an emulsifying, wetting and dispersing agent. This paper reports on predominantly neutron reflectivity, NR, measurements which explore the nature of surface multilayer formation of the sodium salt of AOT at the air-solution interface with the separate addition of Ca2+ and Al3+ counterions. Findings. In the AOT concentration range 0.5 to 2.0 mM surface multilayer formation occurs at the air-solution interface with the addition of Ca2+ or Al3+ counterions. Although the evolution in the surface structure with surfactant and counterion concentration is broadly similar to those reported for SDS, SAES and AES, some notable differences occur. In particular the surfactant and counterion concentration thresholds for surface multilayer formation are higher for Ca2+ than for Al3+. The differences encountered reflect the greater affinity of the di-alkyl chain structure for lamellar formation, and how the surface packing is controlled in part by the headgroup structure and the associated counterion binding affinity.

There is an increased interest in the use of natural surfactant as replacements for synthetic surfactants due to their biosustainable and biocompatible properties. A category of natural surfactants which are attracting much current interest is the triterpenoid saponins; surface active components found extensively in a wide range of plant species. A wide range of different saponin structures exist, depending upon the plant species they are extracted from; but regardless of the variation in structural details they are all highly surface active glycosides. Greater exploitation and application requires a characterisation and understanding of their basic adsorption and self-assembly properties.HypothesisGlycyrrhizic acid, extracted from Licorice root, is a monodesmosidic triterpenoid saponin. It is widely used in cosmetic and pharmaceutical applications due to its anti-inflammatory properties, and is an ingredient in foods as a sweetener additive. It has an additional attraction due to its gel forming properties at relatively low concentrations. Although it has attracted much recent attention, many of its basic surface active characteristics, adsorption and self-assembly, remain relatively unexplored. How the structure of the Glycyrrhizic acid saponin affects its surface active properties and the impact of gelation on these properties are important considerations, and to investigate these are the focus of the study.ExperimentsIn this paper the adsorption properties at the air-water interface and the self-assembly in solution have been investigated using by neutron reflectivity and small angle neutron scattering; in non-gelling and gelling conditions.FindingsThe adsorption isotherm is determined in water and in the presence of gelling additives, and compared with the adsorption behaviour of other saponins. Gelation has minimal impact on the adsorption; apart from producing a rougher surface with a surface texture on a macroscopic length scale. Globular micelles are formed in aqueous solution with modest anisotropy, and are compared with the structure of other saponin micelles. The addition of gelling agents results in only minimal micelle growth, and the solutions remain isotropic under applied shear flow.

A series of nonionic ethoxylate surfactants containing different combinations of alkyl, phenyl, and adamantyl units in nine different arrangements, each combined with penta- and hexa-ethylene glycol groups, were synthesized and purified. The surface properties of all of the surfactants were investigated at the air-water (A-W) interface using surface tension (ST) to determine the limiting surface excess (Γlim), the limiting surface tension (σlim), and the critical micelle concentration (CMC). A smaller selection was investigated at the hydrophilic silica-water interface by neutron reflectometry to obtain the thickness of the adsorbed layer and the total adsorption at the CMC. An unusual and largely unrecognized feature of the ethoxylate group is that it is both hydrophilic and hydrophobic. It was found possible to account for the variation of σlim and Γlim of all of the adsorbed layers in terms of a balance of the estimated STs of the sublayers forming the overall adsorbed layer, including that of the underlying ethoxylate layer. The values of σlim were found to be highest for phenyl- and adamantyl-capped surfactants and lowest mainly when there was more than one methyl group at the surface. However, in terms of the concentration required to reach a given low ST, increasing the number of attached methyl groups was found to be less effective than using a smaller number of better-placed methyl groups. At the solid-liquid interface, adsorption at or above the CMC was in all cases in the form of a fragmented bilayer whose coverage varied approximately linearly with the packing parameter. However, results on the phenyl-capped surfactants showed that the high ST exhibited by these surfactants at the A-W interface becomes a high cohesion energy in the interior of the bilayer and they exhibited significantly higher adsorption than expected from simple packing arguments.

Hypothesis l -carnitine plays a crucial role in the cellular production of energy by transporting fatty acids into mitochondria. Acylated l -carnitines are amphiphilic and if appropriate physical properties were demonstrated, they could replace many currently used surfactants with improved biocompatibility and health benefits. Experiments This work evaluated the surface adsorption of lauroyl- l -carnitine (C12LC) and its aggregation behavior. The size and shape of the aggregates of C12LC surfactant were studied at different temperatures, concentrations, pH and ionic strength by dynamic light scattering (DLS) and small-angle neutron scattering (SANS). Surface tension measurements were carried out to determine the critical micellar concentration (CMC) of C12LC. Combining with the Gibbs equation, the surface excess at different concentrations could be determined. Neutron reflection (NR) was used to determine the structure of the adsorbed layer at the air/water interface with the help of isotopic contrast variations. Findings At pH 7, the limiting area per molecule (ACMC) of the zwitterionic C12LC adsorbed layer at the air/water interface was found to be 46 A2 from surface tension and neutron reflection, smaller than the values of C12PC, C12E5, DTAB, C12C4betaine and C12C8betaine but close to that of SDS. A pronounced surface tension minimum at pH 2 at the low ionic strength was linked to a minimum value of area per molecule of about 30 A2, indicating the competitive adsorption from traces of lauric acid produced by hydrolysis of C12LC. As the concentration increased, area per molecule reached a plateau of 37–39 A2, indicating the dissolution of the more surface-active lauric acid into the micelles of C12LC. DLS and SANS showed that the size and shape of micelles had little response to temperature, concentration, ionic strength or pH. The SANS profiles measured under 3 isotopic contrasts could be well fitted by the core–shell model, giving a spherical core radius of 15.7 A and a shell thickness of 10.5 A. The decrease of pH led to more protonated carboxyl groups and more positively charged micelles, but the micellar structures remained unchanged, in spite of their stronger interaction. These features make C12LC potentially attractive as a solubilizing agent.

By applying the Gibbs equation to the bulk binding isotherms and surface composition of the air–water (A–W) interface in polyelectrolyte–surfactant (PE–S) systems, we show that their surface behavior can be explained semiquantitatively in terms of four concentration regions, which we label as A, B, C, and D. In the lowest-concentration range A, there are no bound PE–S complexes in the bulk but there may be adsorption of PE–S complexes at the surface. When significant adsorption occurs in this region, the surface tension (ST) drops with increasing concentration like a simple surfactant solution. Region B extends from the onset of bulk PE–S binding to the end of cooperative binding, in which the slow variation of surfactant activity with cooperative binding means that the ST changes relatively little, although adsorption may be significant. This leads to an approximate plateau, which may be at high or low ST. Region C starts where the binding in the bulk complex loses its cooperativity leading to a rapid change of surfactant activity with the total concentration. This, combined with significant adsorption, often leads to a sharp drop in ST. Region D is where precipitation and redissolution of the bulk PE–S complex occur. ST peaks may arise in region D because of loss of the solution complex that matches the value of the preferred surface stoichiometry, which seems to have a well-defined value for each system. The analysis is applied to the experimental systems, sodium polystyrene sulfonate–alkyltrimethylammonium bromides and poly(diallyldimethyl chloride)–sodium alkyl sulfates, with and without the added electrolyte, and includes data from bulk binding isotherms, phase diagrams, aggregation behavior, and direct measurements of the surface excess and stoichiometry of the surface. The successful fits of the Gibbs equation to the data confirm that the surfaces in these systems are largely equilibrated.

Low molecular weight (MW) peptides are an attractive choice for bench scale coagulation tests. In this study, water soluble seed proteins from Moringa oleifera were fractionated, characterised and screened for coagulant activity. Seed proteins were extracted from defatted M. oleifera using distilled water, followed by adjustment to pH 7 and sequential ammonium sulphate precipitation. Positive coagulant activity was observed for 40 wt% fraction that was found to contain a mixture of 6 peptides according to sodium dodecyl sulfate polyacrylamide gel electrophoresis under reducing conditions. Dominant peptides had molecular weights of ∼32, ∼14 and ∼10 kDa, respectively. At a total protein concentration of 0.79 ± 0.03 mg/mL, 40 wt% fraction reduced turbidity by 93%. Our findings suggest the 40 wt% fraction to be the most promising protein fraction for water treatment applications.

Loss of conventional NPK fertilizer in low fertility soils not only reduces profit and pollutes ground and surface water but also causes indirect land-use change. Addition of pure biochar to low fertility soil generally improves crop yield and mitigates climate change but requires added value to be viable. This study aims to establish whether industrially produced oil palm kernel shell (OPKS) biochar impregnated with NH4NO3 and KH2PO4 can release nutrients similar to commercially available slow release fertilizer (Agroblen). Impregnation was carried out via soaking for 21 h with a fertilizer-to-OPKS biochar ratio of 25:75 (w/w) followed by oven-drying until constant weight. Distilled water was added to the leaching column containing quartz sand and the impregnated OPKS biochar, soaked for 1 h before collecting the leachate for spectrophotometric analysis. Agroblen was used as positive and OPKS biochar as negative control. Leaching experiments showed that impregnated OPKS biochar had the greatest nutrient release (NO3− was 52.9%, 77.4% for NH3 and 55.2% for PO4) followed by positive and negative control. The carbon sequestration potential of OPKS biochar was estimated to be 0.398 tonnes CO2 per tonne biomass making it a suitable candidate for climate change mitigation and carbon credit trading further research into the impregnation of NP fertilizer on OPKS biochar with suitable coatings is required to improve its nutrient release.

We conducted a systematic review of the literature on the effects of cordycepin on cell survival and proliferation, inflammation, signal transduction and animal models. A total of 1204 publications on cordycepin were found by the cut-off date of 1 February 2021. After application of the exclusion criteria, 791 papers remained. These were read and data on the chosen subjects were extracted. We found 192 papers on the effects of cordycepin on cell survival and proliferation and calculated a median inhibitory concentration (IC50) of 135 µM. Cordycepin consistently repressed cell migration (26 papers) and cellular inflammation (53 papers). Evaluation of 76 papers on signal transduction indicated consistently reduced PI3K/mTOR/AKT and ERK signalling and activation of AMPK. In contrast, the effects of cordycepin on the p38 and Jun kinases were variable, as were the effects on cell cycle arrest (53 papers), suggesting these are cell-specific responses. The examination of 150 animal studies indicated that purified cordycepin has many potential therapeutic effects, including the reduction of tumour growth (37 papers), repression of pain and inflammation (9 papers), protecting brain function (11 papers), improvement of respiratory and cardiac conditions (8 and 19 papers) and amelioration of metabolic disorders (8 papers). Nearly all these data are consistent with cordycepin mediating its therapeutic effects through activating AMPK, inhibiting PI3K/mTOR/AKT and repressing the inflammatory response. We conclude that cordycepin has excellent potential as a lead for drug development, especially for age-related diseases. In addition, we discuss the remaining issues around the mechanism of action, toxicity and biodistribution of cordycepin.

International audience; Background: Ofatumumab, a subcutaneous anti-CD20 monoclonal antibody, selectively depletes B cells. Teriflunomide, an oral inhibitor of pyrimidine synthesis, reduces T-cell and B-cell activation. The relative effects of these two drugs in patients with multiple sclerosis are not known.Methods: In two double-blind, double-dummy, phase 3 trials, we randomly assigned patients with relapsing multiple sclerosis to receive subcutaneous ofatumumab (20 mg every 4 weeks after 20-mg loading doses at days 1, 7, and 14) or oral teriflunomide (14 mg daily) for up to 30 months. The primary end point was the annualized relapse rate. Secondary end points included disability worsening confirmed at 3 months or 6 months, disability improvement confirmed at 6 months, the number of gadolinium-enhancing lesions per T1-weighted magnetic resonance imaging (MRI) scan, the annualized rate of new or enlarging lesions on T2-weighted MRI, serum neurofilament light chain levels at month 3, and change in brain volume.Results: Overall, 946 patients were assigned to receive ofatumumab and 936 to receive teriflunomide; the median follow-up was 1.6 years. The annualized relapse rates in the ofatumumab and teriflunomide groups were 0.11 and 0.22, respectively, in trial 1 (difference, -0.11; 95% confidence interval [CI], -0.16 to -0.06; P

Palm oil mill effluent (POME) is a highly polluted industrial wastewater that may cause detrimental environmental pollution if discharged directly due to its biochemical oxygen demand (BOD) and chemical oxygen demand (COD) concentrations. In the present study, the performance of FeSO4.7H2O waste from titanium oxide industry was investigated in removing BOD, COD, and total suspended solids (TSS) from POME. Jar tests were conducted with varying coagulant doses (1–5 g L−1), pH (2–10), and temperature (40–80 °C) as a function of treatment time ranging from 5 to 90 min. Results show that the FeSO4.7H2O waste can remove about 70% COD, over 80% BOD, and over 85% TSS in a single stage coagulation treatment. The coagulation adsorption mechanisms for the removal of COD, BOD, and TSS from POME were investigated based on Brunauer–Emmett–Teller (BET), Freundlich, and Langmuir isotherm models. The removal of COD, BOD, and TSS from POME was best described by the Freundlich isotherm model, indicating that coagulation adsorption occurred in a multilayer formation with non-uniform distribution of adsorbed particles. The coagulation adsorption kinetics studies revealed that the removal of COD, BOD, and TSS from POME using FeSO4.7H2O waste followed the second-order-kinetics modeling. Our findings suggest that the FeSO4.7H2O waste has the potential to be utilized as a coagulant for treating POME in compliance with the standard discharge limits.

Conventional coagulants, like aluminium sulphate and ferric chloride, are used in potable water treatment and involve non-sustainable mining and transformation of raw materials for their production with costly sludge disposal. Natural coagulants are mostly obtained from bacteria, fungi, animals and plants and are classified as polysaccharide, amino-polysaccharide, poly-phenols and proteins-based substances. Plant-based coagulants extracted from Moringa oleifera, Strychnos potatorum Linn, Plantago ovate, Trigonella foenum graecum and Opuntia ficus indica are potential substitutes to chemicals mostly based on bench-scale testing. These are organic polymers and polyelectrolytes that are classified as cationic, anionic and non-ionic coagulants. This paper provides a historical and contemporary review of plant-based coagulants, their notable milestones achieved, chemistry involved, as well as bench, pilot and full scale trials, highlighting the effects of plant-based coagulants on physico-bio-chemical properties of raw water. Commercialisation constrains are also included and discussed.

Yak dung is used as fuel in Tibetan homes; however, this use is hazardous to health. An alternative use of the dung that would be profitable and offset the loss as a fuel would be very beneficial. Sweet sorghum silage with yak dung biochar as an additive was compared with a control silage with no additives and three silages with different commercial additives, namely Lactobacillus buchneri, Lactobacillus plantarum and Acremonium cellulase. Biochar-treated silage had a significantly greater concentration of water-soluble carbohydrates than the other silages (76 vs 12.4-45.8 g/kg DM) and a greater crude protein content (75.5 vs 61.4 g/kg DM), lactic acid concentration (40.7 vs 27.7 g/kg DM) and gross energy yield (17.8 vs 17.4 MJ/kg) than the control silage. Biochar-treated and control silages did not differ in in vitro digestibility and in total gas (507 vs 511 L/kg DM) and methane production (57.9 vs 57.1 L/kg DM). Biochar inhibited degradation of protein and water-soluble carbohydrates and enhanced lactic acid production, which improved storability of feed. It was concluded that yak dung biochar is an efficient, cost-effective ensiling additive. The profit could offset the loss of dung as fuel and improve the health of Tibetan people.

Hypothesis: The α-sulfo alkyl ester, AES, surfactants are a class of anionic surfactants which have potential for improved sustainable performance in a range of applications, and an important feature is their enhanced tolerance to precipitation in the presence of multivalent counterions. It is proposed that their adsorption properties can be adjusted substantially by changing the length of the shorter alkyl chain, that of the alkanol group in the ester. Experiments: Surface tension and neutron reflectivity have been used to investigate the variation in the adsorption properties with the shorter alkyl chain length (methyl, ethyl and propyl), the impact of NaCl on the adsorption, the tendency to form surface multilayer structures in the presence of AlCl3, and the effects of mixing the methyl ester sulfonate with the ethyl and propyl ester sulfonates on the adsorption. Findings: The variations in the critical micelle concentration, CMC, the adsorption isotherms, the saturation adsorption values, and the impact of NaCl illustrate the subtle influence of varying the shorter alkyl chain length of the surfactant. The non-ideal mixing of pairs of AES surfactants with different alkanol group lengths of the ester show that the extent of the non-ideality changes as the difference in the alkanol length increases. The surface multilayer formation observed in the presence of AlCl3 varies in a complex manner with the length of the short chain and for mixtures of surfactants with different chains lengths.

Decellularized porcine corneal scaffolds are a potential alternative to human cornea for keratoplasty. Although clinical trials have reported promising results, there can be corneal haze or scar tissue. Here, we examined if recellularizing the scaffolds with human keratocytes would result in a better outcome. Scaffolds were prepared that retained little DNA (14.89 ± 5.56 ng/mg) and demonstrated a lack of cytotoxicity by in vitro. The scaffolds were recellularized using human corneal stromal cells and cultured for between 14 in serum-supplemented media followed by a further 14 days in either serum free or serum-supplemented media. All groups showed full-depth cell penetration after 14 days. When serum was present, staining for ALDH3A1 remained weak but after serum-free culture, staining was brighter and the keratocytes adopted a native dendritic morphology with an increase (p < 0.05) of keratocan, decorin, lumican and CD34 gene expression. A rabbit anterior lamellar keratoplasty model was used to compare implanting a 250 μm thick decellularized lenticule against one that had been recellularized with human stromal cells after serum-free culture. In both groups, host rabbit epithelium covered the implants, but transparency was not restored after 3 months. Post-mortem histology showed under the epithelium, a less-compact collagen layer, which appeared to be a regenerating zone with some α-SMA staining, indicating fibrotic cells. In the posterior scaffold, ALDH1A1 staining was present in all the acellular scaffold, but in only one of the recellularized lenticules. Since there was little difference between acellular and cell-seeded scaffolds in our in vivo study, future scaffold development should use acellular controls to determine if cells are necessary.

Saponins are highly surface active glycosides, derived from a wide range of plant species. Their ability to produce stable foams and emulsions has stimulated their applications in beverages, foods, and cosmetics. To explore a wider range of potential applications, their surface mixing properties with conventional surfactants have been investigated. The competitive adsorption of the triterpenoid saponin escin with an anionic surfactant sodium dodecyl sulfate, SDS, at the air-water interface has been studied by neutron reflectivity, NR, and surface tension. The NR measurements, at concentrations above the mixed critical micelle concentration, demonstrate the impact of the relative surface activities of the two components. The surface mixing is highly nonideal and can be described quantitatively by the pseudophase approximation with the inclusion of the quadratic and cubic terms in the excess free energy of mixing. Hence, the surface mixing is highly asymmetrical and reflects both the electrostatic and steric contributions to the intermolecular interactions. The relative importance of the steric contribution is reinforced by the observation that the micelle mixing is even more nonideal than the surface mixing. The mixing properties result in the surface adsorption being largely dominated by the SDS over the composition and concentration range explored. The results and their interpretation provide an important insight into the wider potential for mixing saponins with more conventional surfactants.

open access article Understanding peptide self-assembly mechanisms and stability of the formed assemblies is crucial for the development of functional nanomaterials. Herein, we have adopted a rational design approach to demonstrate how a minimal structural modification to a nonassembling ultrashort ionic selfcomplementary tetrapeptide FEFK (Phe4) remarkably enhanced the stability of self-assembly into β-sheet nanofibers and induced hydrogelation. This was achieved by replacing flexible phenylalanine residue (F) by the rigid phenylglycine (Phg), resulting in a constrained analogue PhgEPhgK (Phg4), which positioned aromatic rings in an orientation favorable for aromatic stacking. Phg4 self-assembly into stable β-sheet ladders was facilitated by π-staking of aromatic side chains alongside hydrogen bonding between backbone amides along the nanofiber axis. The contribution of these noncovalent interactions in stabilizing self-assembly was predicted by in silico modeling using molecular dynamics simulations and semiempirical quantum mechanics calculations. In aqueous medium, Phg4 β-sheet nanofibers entangled at a critical gelation concentration ≥20 mg/mL forming a network of nanofibrous hydrogels. Phg4 also demonstrated a unique surface activity in the presence of immiscible oils and was superior to commercial emulsifiers in stabilizing oil-in-water (O/W) emulsions. This was attributed to interfacial adsorption of amphiphilic nanofibrils forming nanofibrilized microspheres. To our knowledge, Phg4 is the shortest ionic self-complementary peptide rationally designed to self-assemble into stable β-sheet nanofibers capable of gelation and emulsification. Our results suggest that ultrashort ionic-complementary constrained peptides or UICPs have significant potential for the development of cost-effective, sustainable, and multifunctional soft bionanomaterials.

The adsorption of the polyelectrolyte-cationic surfactant mixture of sodium poly(acrylic acid), NaPAA, and dodecyl trimethyl ammonium bromide, C 12TAB, at the air-water interface has been studied using neutron reflectivity and surface tension. The results provide direct evidence of the relative roles of the electrostatic and hydrophobic interactions between the polyelectrolyte and surfactant on the adsorption behaviour. At both pH 4.2 and 9.2 the addition of NaPAA results in a strong reduction in the surface tension at low C12TAB concentrations, consistent with the adsorption of polymer-surfactant complexes at the interface. This is confirmed and quantified by neutron reflectivity measurements. At pH 4.2 a mixed polymer-surfactant monolayer (∼20 Å thick) is adsorbed at the interface over the entire surfactant concentration range measured. Whereas at pH 9.2, where the polyelectrolyte is more highly charged, the adsorption pattern is similar at low surfactant concentrations to that measured at low pH. However, at higher surfactant concentrations there is a transition from monolayer adsorption to the formation of a 'layered' structure at the interface. This is indicative of a stronger polymer-surfactant interaction at the surface, and has some similarity with that observed in other polyelectrolyte-ionic surfactant mixtures. At high pH, the results imply that at the lower surfactant concentrations the adsorption is dominated by the hydrophobic interaction, whereas at higher surfactant concentrations it is dominated by the electrostatic interaction. At low pH the dominant interaction would appear to be hydrophobic in nature. © The Royal Society of Chemistry 2005.

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Louis-Ferdinand, Robert Thomas, Ph.D. , University of Rhode Island August, 1969. The Modification of Hepatic Microsomal Drug Metabolism by Phenobarbital and Amphetamine. Major Professor: Dr. George C. Fuller. This investigation was carried out to provide a mechanistic explanation for the modification of hepatic microsomal drug metabolism produced by amphetamine· and phenobarbital. The influence of phenobarbital administration on the activity of microsomal ribonuclease during induction of drug-metabolizing enzymes, was determined. Administration of phenobarbital (100 mg/kg) for six days resulted in a significant (P .£0. 05) increase in hepatic microsomal oxidative demethylation. Conversely, hepatic microsomal ribonuclease activity of phenobarbital-treated rats was significantly reduced to less than 5% of control values. When phenobarbital (50 mg/kg) was administered for 5 days ribonuclease activity was inhibited to about one-half of control values. Phenolpthalein {3-glucuronidase activity of hepatic microsomal fractions obtained from phenobarbital treated animals was not significantly (P) O. 05) different from controls. Phenobarbital(lxlo-\1olar) did not inhibit ribonuclease activity following in vitro additions to the assay system. Time-response studies were. conducted following the administration of a single dose of phenobarbital (100 mg/kg). Results of these studies indicated that microsomal p-chloro-N-methylaniline (PCMA) demethylase stimulation and ribonuclease inhibition were temporaily related, except for a 24 hour lag in the PCMA demethylase response. Administration of phenobarbital (50 mg/kg twice-daily) produced significant inhibition of ribonuclease and stimulaticn of drug metabolism in liver microsomes of intact, adrenalectomized or hypophysectomized rats. Administration of 3-methylcholanthrene (40 mg/kg) to male rats resulted in a non-significant inhibition of ribonuclease activity while p-nitroanisole demethylation was stimulated three-fold. In vitro recombination experiments in which 105, 000 x g rat liver supernatants from control and treated animals were combined ·with rnicrosomes

Previous biochar research has primarily focused on agricultural annual cropping systems with very little attention given to highly fragile, complex and diverse natural alpine grassland ecosystems. The present study investigated the effect of biochar on the growth of alpine meadows and soil health. This study was conducted in the Qinghai Tibetan Plateau over a three year period to investigate the effect of three rice husk biochar application rates alone and combination with high and low NPK fertilizer dosages on alpine meadow productivity, soil microbial diversity as well as pH, carbon and nitrogen content at 0–10 cm and 10–20 cm depth. At the end of the 3rd year soil samples were analysed and assessed by combined analysis of variance. The results showed that biochar application in combination with nitrogen (N), phosphorus (P) and potassium (K) fertilizer had a significant increase in fresh and dry biomass during the second and third year of the study as compared to control and alone biochar application (p ≤ 0.05). Biochar alone and in combination with NPK fertilizer resulted in a significant increase in the soil pH and carbon contents of the soil. XPS results, the SEM imaging and EDS analysis of aged biochar demonstrated that the biochar has undergone complex changes over the 3 years as compared to fresh biochar. This research suggests that biochar has positive effect on alpine meadow growth and soil health and may be an effective tool for alpine meadow restoration.

The structures of layers of three different dodecylcarboxybetaine surfactants adsorbed at the air-water interface have been determined by neutron reflection. The zwitterionic compounds differed in the length of the spacer separating the quaternary ammonium and carboxylate groups, which was (CH2)1, (CH2)4, or (CH2)8. The limiting area per molecule was found to be 45, 52, or 84 Å(2), respectively, and compared reasonably with results from surface tension showing that the Gibbs prefactor is 1 in each case. Isotopic labeling was used to distinguish between the position of the alkyl and spacer groups in the layer. The spacer was found to be well-immersed in water for the (CH2)1 and (CH2)4 spacers but significantly above water for the (CH2)8 spacer. The distribution of the (CH2)8 spacer along the surface normal was found to be similar to that of the dodecyl group; i.e., it projects out of the water, contrary to an earlier hypothesis that it forms a loop. Comparison of the overlap of water with dodecyl and spacer groups also indicates that the (CH2)8 spacer is well out of the water. This in turn suggests that the anionic carboxylic acid group, which is dissociated in solution, is not ionized in the adsorbed layer. A further observation is that the dodecylcarboxybetaine with the (CH2)8 spacer reaches surface saturation at one-tenth of the critical micelle concentration. This is highly unusual and is attributed to the long spacer destabilizing the micelle relative to the surface layer.

Optimising detergency at lower temperatures is of increasing interest due to environmental and economic factors, and requires a greater understanding of the effects of temperature on the adsorption of surfactant mixtures at interfaces. The adsorption properties of surfactant mixtures and biosurfactant/surfactant mixtures have been studied at room temperatures and at temperatures below ambient using surface tension and neutron reflectivity measurements. For the ternary surfactant mixture of octaethylene monododecyl ether, C12E8, sodium dodecyl 6-benzene sulfonate, LAS, and sodium dioxyethylene glycol monododecyl sulfate, SLES, the surface tension at the air-water interface increases with decreasing temperature. In contrast, there is a notable reduction in the increase in the surface tension with a decrease in temperature from 25 °C to 10 °C for the 5 component rhamnolipid/surfactant mixture of the mono-rhamnose, R1, and di-rhamnose, R2, with C12E8/LAS/SLES. The associated neutron reflectivity data for the ternary C12E8/LAS/SLES mixture and the significant observation is that the 3, 4, and 5-component mixtures containing rhamnolipids in conjunction with the other surfactants show changes in composition and adsorbed amounts of the individual components which are close to the experimental error. However the significant observation is that the neutron reflectivity data indicate that the improved surface tension tolerance at lower temperatures is associated with the dominance of the rhamnolipid adsorption in such mixtures. Hence the introduction of the rhamnolipids provides a tolerance to the adverse effects associated with reduced temperatures, and a potential for improved detergency at relatively low temperatures.

There is an increasing interest in biosustainable surfactants and surface active proteins for a range of applications, in home and personal care products, cosmetics, pharmaceuticals, and food and drink formulations. This review focuses on two plant derived biosurfactants, the surface active glycoside, saponin, and the surface active globular protein, hydrophobin. A particular emphasis in the review is on the role of neutron reflectivity in probing the adsorption, structure of the adsorbed layer, and their mixing at the interface with a range of more conventional surfactants and proteins.

Saponins are surface active glycosides which can be extracted from a range of different plant species. This class of biosurfactants is of much current interest because of their biocompatibility and biosustainability, and a range of other interesting properties. The Quillaja saponin, the focus of this paper, is extensively used in foods, beverages and cosmetics due to their accessibility and agency approval. Aspects of their wider application rests with their use in combination with different synthetic surfactants, to optimise and tailor performance and functionality. Characterising and understanding the self-assembly of such mixtures is an essential requirement for that wider exploitation. The surface activity of a range of different saponins has been extensively reported, but the self-assembly properties of the Quillaja saponin, and its mixture with different synthetic surfactants has not been reported in any detail. Of particular interest is how the bidesmodic structure of the Quillaja saponin and the mixing with the different cosurfactants affects the evolution in the micelle structure, and this is the focus of this study. Small angle neutron scattering, SANS, has been used to characterise the micelle formation of the Quillaja saponin and of its mixtures with the anionic surfactant sodium dodecyl sulfate, SDS, and the nonionic surfactants, dodecaethylene glycol monododecyl ether, C12E12, and pentaethylene glycol monododecyl ether, C12E5. The Quillaja saponins form relatively small globular micelles with a relatively small aggregation number. In mixtures with SDS and the nonionic surfactants the micelles retain their globular structure. In the mixtures the micelle aggregation number evolves towards the value for the pure synthetic surfactant component, as the packing constraints change with the decreasing mole fraction of saponin in the micelle. The evolution in the micelle structure and size reflects the change in the structure and geometry of the associated surfactant components, and is largely dominated by the Quillaja structure. The results provide an interesting insight into the factors controlling the self-assembly in saponin – surfactant mixtures, and how the saponin structure affects the self-assembly.

Surface compositions of adsorbed monolayers at the air/water interface, formed from binary surfactant mixtures in equilibrium, have been studied using neutron reflectivity at three discrete temperatures: 10, 25, and 40 °C. The binary compositions studied are sodium lauryl dodecyl ether sulfate (SLES EO3)/C12E n, where n = 6 and 8, at a fixed concentration of 2 mM with and without the addition of 0.1 M NaCl. Without NaCl, the nonionic surfactant dominates at the interface and nonideal mixing behavior is observed. This is modeled using the pseudophase approximation with a quadratic expansion of the free energy of mixing. The addition of 0.1 M NaCl screens the charge interaction between the surfactants and drives the surface composition of each system closer to that of the bulk composition. However, model fits to both the micelles and surface layers suggest that nonideal mixing is still taking place, although it is difficult to establish the extent of nonideality due to the limited data quality. The effect of temperature changes on the surface adsorption and composition of the surfactant mixtures is minimal and within error, with and without NaCl, but the critical micelle concentrations are significantly affected. This indicates the dominant influence of steric hindrances and surfactant charge interactions in determining interfacial behavior for these surfactants, relative to the temperature changes. The study also highlights the delicate effect of a relatively small change in the number of EO groups on mixing behavior.

Coumarin therapy has been associated with high levels of inter- and intra-individual variation in the required dose to reach a therapeutic anticoagulation outcome. Therefore, a dynamic system that is able to achieve accurate delivery of a warfarin dose is of significant importance. Here we assess, the ability of 3D printing to fabricate and deliver tailored individualised precision dosing using an in-vitro model. Sodium warfarin loaded filaments were compounded using hot melt extrusion (HME) and further fabricated via fused deposition modelling (FDM) 3D printing to produce capsular-ovoid-shaped dosage forms loaded at 200 and 400 µg dose. The solid dosage forms and comparator warfarin aqueous solutions were administered by oral gavage to Sprague-Dawley rats. In vitro, warfarin release was faster at pH 1.2 in comparison to pH 2. A novel UV imaging approach indicated that the erosion of the methacrylate matrix was at a rate of 16.4 and 15.2 µm/min for horizontal and vertical planes respectively. In vivo, 3D printed forms were as proportionately effective as their comparative solution form in doubling plasma exposure following a doubling of warfarin dose (184% versus 192% respectively). The 3D printed ovoids showed a lower C of warfarin (1.51 and 3.33 mg/mL versus 2.5 and 6.44 mg/mL) and a longer T (6 and 3.7 versus 4 and 1.5 h) in comparison to liquid formulation. This work demonstrates for the first time in vivo, the potential of FDM 3D printing to produce a tailored specific dosage form and to accurately titrate coumarin dose response to an individual patient. [Abstract copyright: Copyright © 2018. Published by Elsevier B.V.]

Conventional immediate release dosage forms involve compressing the powder with a disintegrating agent that enables rapid disintegration and dissolution upon oral ingestion. Among 3D printing technologies, the fused deposition modelling (FDM) 3D printing technique has considerable potential for patient-specific dosage form. However, the use of FDM 3D printing in tablet manufacturing requires large portion of polymer, which slows down drug release through erosion and diffusion mechanisms. In this study, we demonstrate for the first time the use of a novel design approach of caplets with perforating channels to accelerate drug release from 3D printed tablets. This strategy has been implemented using a caplet design with perforating channels of increasing width (0.2, 0.4, 0.6, 0.8 or 1.0mm) and variable length, and alignment (parallel or at right angle to tablet long axis). Hydrochlorothiazide (BCS class IV drug) was chosen as model drug as enhanced dissolution rate is vital to guarantee oral bioavailability. The inclusion of channels exhibited an increase in the surface are/volume ratio, however, the release pattern was also influenced by the width and the length of the channel. A channel width≥0.6mm deemed critical to meet the USP criteria of immediate release products. Shorter multiple channels (8.6mm) were more efficient at accelerating drug release than longer channels (18.2mm) despite having comparable surface area/mass ratio. This behaviour may be linked to the reduced flow resistance within the channels and the faster fragmentation during dissolution of these tablets. In conclusion, the width and length of the channel should be carefully considered in addition to surface area/mass when optimizing drug release from 3D printed designs. The incorporation of short channels can be adopted in the designs of dosage forms, implants or stents to enhance the release rate of eluting drug from rich polymeric structures. [Abstract copyright: Copyright © 2017. Published by Elsevier B.V.]

In the present study, the leaching of Cu(II) from the waste mobile phone printed circuit board (WM-PCB) was investigated using concentrated sulphuric acid solution. Cu(II)) uptake efficiency was determined at varying pH (pH 2.0 – pH 8.0), temperatures (40 oC-80 oC) and treatment time (15 - 90 min). It was observed that the copper uptake increased with increasing temperature and acid concentration. The highest Cu(II) uptake was found to be 190 mg/g at pH 6.0 and 80°C within 60 min. Results indicate that sulphuric acid has the potential to recover the heavy metals from WM-PCB.

Saponins are plant based biosurfactants that are obtained from a wide variety of plant species. They are surface active glycosides with a hydrophobic group, which is commonly a triterpenoid or steroidal group, and saccharide hydrophilic units. Their structures are markedly different from conventional synthetic surfactants, and present interesting challenges in understanding their optimal packing in self-assembled structures such as micelles. Furthermore the wide variety of molecular structures available provide interesting opportunities to optimise the packing in mixed systems. In the current literature there is limited information available on saponin self-assembly, and especially in saponin mixtures. The general view is that globular to more elongated micelle structures form at relatively low concentrations. Here small angle neutron scattering, SANS, is used to investigate and quantify the structure of escin, tea and glycyrrhizic acid micelles and particularly of escin/tea, tea/glycyrrhizic acid and escin/glycyrrhizic acid mixtures at relatively low concentrations. The focus is principally on how the different saccharide headgroup structures affect the self-assembly. Tea saponins form relatively small globular micelles, whereas escin and glycyrrhizic acid form larger more elongated globular micelle structures. The micelle structure and changes observed reflect the packing constraints associated with the aglycone triterpenoid hydrophobic section and the differences in the saccharide headgroups. In the escin/tea and glycyrrhizic acid/tea mixtures the greater intrinsic curvature associated with the tea saponin dominates the micelle structure over much of the composition range explored. For the escin/glycyrrhizic acid mixture the micelle size and aggregation number go through a minimum at an approximately equimolar composition, and this implies an intrinsic difficulty in efficient packing of the two different saponin structures, which results in an increase in the preferred curvature

Saponins are a class of bio-surfactants obtained from a wide variety of plant species. They are surface active glycosides which are used in the stabilisation of foams and emulsions in many food, drink and cosmetic applications. Their wider utilisation and application will involve their mixture with different synthetic and bio-derived surfactants, proteins and polymers. Understanding the mixing properties of saponins with other surfactants at surfaces and in self-assembly is key to their wider exploitation; and the focus here is on triterpenoid saponin escin and the anionic surfactant sodium dodecylsulfate, SDS. Previous analysis of the surface adsorption and critical micelle concentration, cmc, data using the pseudo phase approximation, PPA, indicate that the micelle mixing is more non-ideal than the surface mixing. The non-ideality is associated with the packing constraints arising from the quite different molecular structures and how this impacts upon the mixture self-assembly is probed here. To address specifically the self-assembly properties of saponin-surfactant mixtures, small angle neutron scattering, SANS, has been used to explore the nature of mixed micelles of escin and SDS. The SANS data for the escin / SDS mixtures are modelled as globular ellipsoidal micelles. The micelles exhibit an overall increase in size and aggregation number as the solution becomes richer in escin, and the evolution in micelle size goes through a minimum at relatively rich SDS solutions. The results illustrate the impact of the disparity in the molecular structures of escin and SDS on the self-assembly, and provides an insight into the factors affecting the departure from ideal mixing.

The ICH M7(R1) guideline describes a framework to assess the carcinogenic risk of mutagenic and carcinogenic pharmaceutical impurities following less-than-lifetime (LTL) exposures. This LTL framework is important as many pharmaceuticals are not administered for a patient's lifetime and as clinical trials typically involve LTL exposures. While there has been regulatory caution about applying LTL concepts to cohort of concern (COC) impurities such as N-nitrosamines, ICH M7 does not preclude this and indeed literature data suggests that the LTL framework will be protective of patient safety for N-nitrosamines. The goal was to investigate if applying the LTL framework in ICH M7 would control exposure to an acceptable excess cancer risk in humans. Using N-nitrosodiethylamine as a case study, empirical data correlating exposure duration (as a percentage of lifespan) and cancer incidence in rodent bioassays indicate that the LTL acceptable intake (AI) as derived using the ICH M7 framework would not exceed a negligible additional risk of cancer. Therefore, controlling N-nitrosamines to an LTL AI based on the ICH M7 framework is thus demonstrated to be protective for potential carcinogenic risk to patients over the exposure durations typical of clinical trials and many prescribed medicines.

Bradykinin (BK) promotes insulin sensitivity and glucose uptake in adipocytes and other cell types. We demonstrated that in rat adipocytes BK enhances insulin-stimulated glucose transport via endothelial nitric oxide synthase, nitric oxide (NO) generation, and decreased activity of the mitogen-activated protein kinase (MAPK) JNK (c-Jun NH2-terminal kinase). In endothelial cells, NO increases soluble guanylate cyclase (sGC) activity, which, in turn, activates protein kinase G (PKG) by increasing cGMP levels. In this study, we investigated whether BK acts via the sGC-cGMP-PKG pathway to inhibit the negative effects of JNK on insulin signaling and glucose uptake in rat adipocytes. BK augmented cGMP concentrations. The BK-induced enhancement of insulin-stimulated glucose uptake was mimicked by the sGC activator YC-1 and a cell-permeable cGMP analog, CPT-cGMP, and inhibited by the sGC inhibitor ODQ and the PKG inhibitor KT 5823. Transfection of dominant-negative PKG reduced the BK augmentation of insulin-induced Akt phosphorylation. The activation of JNK and ERK1/2 by insulin was attenuated by BK, which was mediated by the sGC-cGMP-PKG pathway. Whereas insulin-stimulated phosphorylation of upstream activators of JNK and ERK, i.e., MKK4 and MEK1/2, was unaffected, BK augmented insulin-mediated induction of MKP-5 mRNA and protein levels. Furthermore, zaprinast, a phosphodiesterase inhibitor, enhanced cGMP and MKP-5 and prolonged the action of BK. These data indicate that BK enhances insulin action by inhibition of negative feedback by JNK and ERK via upregulation of MKP-5, mediated by the sGC-cGMP-PKG signaling pathway.

Manufacture of red blood cells (RBCs) from progenitors has been proposed as a method to reduce reliance on donors. Such a process would need to be extremely efficient for economic viability given a relatively low value product and high 2E12 cell dose. Therefore, the aim of these studies was to define the productivity of an industry standard stirred-tank bioreactor and determine engineering limitations of commercial RBC production. Cord blood derived CD34+ cells were cultured under erythroid differentiation conditions in a stirred micro-bioreactor (ambr™). Enucleated cells of 80% purity could be created under optimal physical conditions: pH 7.5, 50% oxygen, without gas-sparging (which damaged cells) and with mechanical agitation (which directly increased enucleation). O2 consumption was low (~5x10(-8) µg/cell.hr) theoretically enabling erythroblast densities in excess of 5x10(8) /ml in commercial bioreactors and sub-10 L/unit production volumes. The bioreactor process achieved a 24% and 42% reduction in media volume and culture time respectively relative to unoptimized flask processing. However, media exchange limited productivity to 1 unit of erythroblasts per 500 L of media. Systematic replacement of media constituents, as well as screening for inhibitory levels of ammonia, lactate and key cytokines did not identify a reason for this limitation. We conclude that the properties of erythroblasts are such that the conventional constraints on cell manufacturing efficiency, such as mass transfer and metabolic demand, should not prevent high intensity production; furthermore this could be achieved in industry standard equipment. However, identification and removal of an inhibitory mediator is required to enable these economies to be realized.

Background & Aim One of the most effective vehicles for delivery of therapeutic nucleic acids are viral vectors, demonstrated by their utility in many commercial cell and gene therapies. Despite success, gaps remain in the optimization of viral vector storage. Traditional polypropylene snap- and screw-cap vials used in academic and research settings do not have the closure integrity or inert properties required for storage of a commercial drug product. Further, glass vials commonly used for protein biologic drug products have not been fully characterized in the context of viral vectors, which have a need for colder storage temperatures and an associated need for increased break resistance. In the present work, two vial types used for biologic drug product storage, cyclic olefin polymer (COP) and glass, were evaluated for preservation of adeno-associated virus (AAV) during low-temperature storage. Methods, Results & Conclusion Preservation of AAV was evaluated using an AAV2 serotype GFP expression vector that was stored frozen at -80°C in either COP or glass vials. Different storage volumes were investigated in both vial types to determine if surface area-to-volume ratio would have any effect on viral recovery. A quantitative viral titer assay was used to measure any loss of nucleic acid content during the freeze-thaw process and HEK293 transduction efficiency was evaluated as a functional readout using flow cytometry. Overall, viral recovery was greater for larger volume samples, indicating that surface area-to-volume ratio of the storage container may be an important consideration during viral gene therapy formulation. Further, AAV recovery was greater after storage in COP as compared to storage in glass. The results provide baseline data indicating that the storage container used for a viral vector therapy can affect product quality, and that the COP vial may serve as a preferred container for commercial viral vector storage.

Enhanced surface delivery and retention of perfumes at interfaces are the keys to their more effective and efficient deployment in a wide range of home and personal care related formulations. It has been previously demonstrated that the addition of multivalent counterions, notably Ca(2+), induces multilayer adsorption at the air-water interface for the anionic surfactant, sodium dodecyl-6-benzenesulfonate, LAS-6. Neutron reflectivity, NR, measurements are reported here which demonstrate that such surfactant surface multilayer structures are a potentially promising vehicle for enhanced delivery of perfumes to interfaces. The data show that the incorporation of the model perfumes, phenylethanol, PE, and linalool, LL, into the surface multilayer structure formed by LAS-6/Ca(2+) results in the surface structures being retained up to relatively high perfume mole fractions. Furthermore the amount of perfume at the surface is enhanced by at least an order of magnitude, compared to that co-adsorbed with a surfactant monolayer.

Surface tension (ST) and neutron reflection (NR) measurements have been made on a series of mixtures of two ionic surfactants, one anionic (SDS) and one cationic (C12TAB), with the two zwitterionic surfactants dodecyldimethylammonium propanesulfonate (C12SB) and dodecyldimethylammonium acetate C12CB. The anionic surfactant SDS interacts equally strongly with both zwitterionics and the C12TAB less strongly. For the SDS-C12SB mixtures simultaneous fitting of ST and NR data made it possible to use the pseudophase approximation with an expansion of the excess free energy, GE, up to and including the quartic term. GE is asymmetric for the adsorbed layer and the minimum occurs at a surface mole fraction, xSDS, of 0.38 with a depth of -2.8RT. NR was also used to follow the adsorption above the CMC, and the changes showed that the intramicellar interaction is more asymmetric, but weaker than the surface interaction with a depth of GE of -2.2RT at the minimum of xSDS = 0.23. A strong synergy in the total surface excess was observed above the mixed CMC with an enhancement over the adsorption of the pure components of about 45%, which appears to result from a sharp variation of the packing with surface composition coupled with the effects of the strongly asymmetric micellization. NR data on SDS-C12CB showed that GE for both surface and micelles was similarly asymmetric to those for SDS-C12SB, but there is no strong synergy in adsorption. This is attributed to the more rigid headgroup. C12TAB-C12SB has an asymmetric GE for both surface and micelle similar to those for SDS-C12SB but the depths are smaller at -0.6RT and -0.5RT, respectively, and there is no synergy in the total adsorption.

A full comparison of results from binding isotherms and surface tension (ST) measurements on polyelectrolyte (PE)–surfactant (S) mixtures, especially the polymer dependence, shows up clear distinctions between the behavior of two representative PE–S systems, poly(sodium styrenesulfonate) (NaPSS) with dodecyltrimethylammonium bromide (C12TAB) and poly(dimethyldiallylammonium chloride) (PDMDAAC) with sodium dodecylsulfate (SDS) in 100 mM NaCl. The surfactant–monomer binding constant in NaPSS–C12TAB is an order of magnitude greater than that in the PDMDAAC–SDS–NaCl system. This results in the ST behavior being dominated largely by non-cooperativity in the former and by cooperativity in the latter. This leads to the ST in PDMDAAC–SDS–NaCl being at its lowest when the average bound fraction is low but increasing rapidly as saturation approaches. A full analysis is also given of how this is altered in the mixture of PDMDAAC–SDS–NaCl with the nonionic surfactant hexethylene glycol monododecyl ether. In contrast, the much stronger interaction in NaPSS–C12TAB leads to high ST complexes at low bound fractions, whereas the lowest ST occurs near the maximum bound fraction, close to or at precipitation. In the PDMDAAC–SDS–NaCl system, the ST drops to a low value at low surfactant concentrations but then increases to a high value just before precipitation occurs, which, combined with increasing surface adsorption of the free surfactant, results in a sharp ST peak. In the NaPSS–C12TAB system, the ST does not drop until the system is at or close to precipitation and it then stays on a plateau until the point at which free surfactant takes over. Thermodynamics does not allow large step changes in the ST, and it is suggested that where these have been observed they are the result of self-depletion of PE or PE–S complexes on the finely divided precipitate of the complex and are therefore not representative of full equilibrium.

A Markov chain (MC) model has been used to model the following binary surfactant mixtures: linear alkylbenzenesulfonate (LAS4)/octaethylene glycol monododecyl ether (C12E8) at 10 and 25 °C, LAS6/acidic sophorolipid (AS), C12Betaine/C12Maltoside, sodium lauryl ether sulfate (SLES2)/C12E8, and rhamnolipid (R1)/LAS6. The critical micellar concentration and the composition of the adsorbed layer, for each system, can be modeled using the same monomer reactivity ratio values, g1 and g2. This implies that the interactions between the surfactants in the bulk solution and at the interface are the same, within error. For the LAS4/C12E8 system at 25 °C, the ranges of g1 and g2 values which can model both sets of data are within 0.03–0.05 and 1.55–2.10, respectively; g1 ≪ g2 implies that C12E8 is significantly more surface active than LAS4. The MC model indicates a negative change in the free energy upon mixing for all of the surfactant systems, consistent with the literature. The interfacial mixing behavior of LAS4/...

The direct reaction of methyl chloride with magnesium and palladium infused silica substrates to synthesize methyl chlorosilanes is reported. First, high energy ball milling on solid Mg-SiO2 mixtures produces elemental silicon and MgO. When PdCl2 is infused into the mixture, after additional ball milling and high-temperature reduction under H2 , dipalladium silicide (Pd2 Si) is produced. The silicon of the Pd2 Si readily reacts with MeCl under Muller-Rochow reaction conditions, to produce methyl chlorosilanes at yield ratios analogous to those of the traditional process. The dominant product is Me2 SiCl2 (selectivity > 30%), followed by MeSiCl3 and Me3 SiCl, with minor amounts of the remaining chlorosilanes. Silicon conversion exceeds 20% for most of the substrates. The elemental palladium, which remains within the Pd-Mg-SiO2 contact mass is re-converted to Pd2 Si at the next H2 /high-temperature treatment and reacts again with MeCl to repeat the methyl chlorosilane production. In principle, the resulting cycle of the mechanochemically induced formation of Pd2 Si followed by the reaction with MeCl can be repeated until the starting SiO2 converts completely to methyl chlorosilanes.

Coagulant proteins from Moringa oleifera (MO) seeds were successfully purified by removing seed oil followed by a protein salting out method at 40% (NH 4 ) 2 SO 4 combined with subsequent dialysis and heat treatment. A microtiter plate-based coagulation activity assay was then performed using colloidal bentonite solution and alum as positive control. The results show an oil recovery of 40 ± 2% while the water-soluble protein fraction in the defatted MO seed was 12.5 ± 0.5 mg/g or 4.4% of the total seed protein content. Heating the desalted protein fraction to 121 °C helped to obtain a 94% pure protein of approximately 7 kDa. Computational analyses support the hypothesis that the coagulating MO protein is an intrinsically disordered protein, providing reason for its stability at extreme temperatures (121 °C). The purified, thermo-stable coagulating protein retained its coagulating activity paving the way to economically produce a sterile natural coagulant from MO seeds.

Significantly enhanced adsorption at the air-water interface arises in polyelectrolyte/ionic surfactant mixtures, such as poly(ethylenimine)/sodium dodecyl sulfate (PEI/SDS), down to relatively low surfactant concentrations due to a strong surface interaction between the polyelectrolyte and surfactant. In the region of charge neutralization this can result in precipitation or coacervation and give rise to undesirable properties in many applications. Ethoxylation of the PEI can avoid precipitation, but can also considerably weaken the interaction. Localization of the ethoxylation can overcome these shortcomings. Further manipulation of the polyelectrolyte-surfactant interaction can be achieved by selective ethoxylation and propoxylation of the PEI amine groups. Neutron reflectivity and surface tension data are presented here which show how the polyelectrolyte-surfactant interaction can be manipulated by tuning the PEI structure. Using deuterium labeled surfactant and polymer the neutron reflectivity measurements provide details of the surface composition and structure of the adsorbed layer. The general pattern of behavior is that at low surfactant concentrations there is enhanced surfactant adsorption due to the strong surface interaction; whereas around the region of the SDS critical micellar concentration, cmc, the surface is partially depleted of surfactant in favor bulk aggregate structures. The results presented here show how these characteristic features of the adsorption are affected by the degree of ethoxylation and propoxylation. Increasing the degree of propoxylation enhances the surfactant adsorption, whereas varying the degree of ethoxylation has a less pronounced effect. In the region of surfactant surface depletion increasing both the degree of ethoxylation and propoxylation result in an increased surface depletion.