On the randomized Horn problem and the surface tension of hives

Our objective was to determine changes in surface tension of tracheal aspirate over the first 4-5 days of life in babies with hyaline membrane disease, with and without synthetic surfactant replacement. Tracheal aspirates were collected prior to and for 96-108 hr after initiation of a randomized double-blind trial of synthetic surfactant (EXOSURF Neonatal) or air-treated control patients. Using the captive bubble technique, we measured minimum surface tension (initial adsorption, first quasi-static compression, dynamic cycling at 30 cpm, second quasi-static compression and 5 min after quasi-static compressions) in 39 surfactant-treated and 44 control babies. We also compared minimum surface tension with the respiratory support provided. Twelve hours after one dose of synthetic surfactant, minimum surface tension on first quasistatic compression decreased significantly from 20.9+/-1.4 to 17.6+/-1.3 mN/m compared to air-treated babies, who did not show any change. Reduction in minimum tracheal aspirate surface tension on first quasi-static compression and during dynamic cycling over 48-60 hr occurred more rapidly in surfactant-treated babies. Ventilator support did not correlate with minimum tracheal aspirate surface tension. We conclude that treatment of babies with synthetic surfactant improved tracheal aspirate minimum surface tension within 12 hr of the first dose and for the next 48-60 hr.

To the Editor: The paper of Bachofen, Gerber, and Schurch, which appeared in the September 2002 issue of the Journal ([1][1]), is seriously misinformed and consequently substantially misleading. The aim of the reported study was to assess the effect of fixatives on structure-function relationships

This paper reports the preparation of polymeric surfactants (HPSO) via a two-step synthetic procedure: polymerization of soybean oil (PSO) in supercritical carbon dioxide followed by hydrolysis of PSO (HPSO) with a base. HPSO was characterized and identified by using a combination of FTIR, (1)H NMR, (13)C NMR, and GPC methods. The effects of HPSO polysoaps on the surface tension of water and interfacial tension of water-hexadecane were investigated as a function of concentration of HPSO and counterion chemistry. HPSO polysoaps were effective at lowering the surface tension of water and the interfacial tension of water-hexadecane. They displayed minimum values of surface tension in the range of 20.5-39.6 dyn/cm at a concentration range of 3.2-32 μM and minimum values of interfacial tension in the range of 15.6-31.44 dyn/cm. The minimum surface and interfacial tension values were highly dependent on the nature of the counterion and increased in the order K(+) < Na(+) < TEA(+). These results suggested that a very low concentration of surfactant can be used to reduce the surface tension of water and interfacial tension of water-hexadecane. Water-hexadecane interfacial energy was also calculated from measured surface tension data using Antonoff, harmonic mean (HM), and geometric mean (GM) methods. Measured values agreed well with those calculated using the HM and GM. The HM method predicted slightly higher values than the GM method, but the Antonoff method did not agree with measured values.

OF THE DISSERTATION Optimal upper bound for the infinity norm of eigenvectors of random matrices by Ke Wang Dissertation Director: Professor Van Vu Let Mn be a random Hermitian (or symmetric) matrix whose upper diagonal and diagonal entries are independent random variables with mean zero and variance one. It is well known that the empirical spectral distribution (ESD) converges in probability to the semicircle law supported on [−2, 2]. In this thesis we study the local convergence of ESD to the semicircle law. One main result is that if the entries of Mn are bounded, then the semicircle law holds on intervals of scale log n/n. As a consequence, we obtain the delocalization result for the eigenvectors, i.e., the upper bound for the infinity norm of unit eigenvectors corresponding to eigenvalues in the bulk of spectrum, is O( √ log n/n). The bound is the same as the infinity norm of a vector chosen uniformly on the unit sphere in Rn. We also study the local version of Marchenko-Pastur law for random covariance matrices and obtain the optimal upper bound for the infinity norm of singular vectors. This is joint work with V. Vu. In the last chapter, we discuss the delocalization properties for the adjacency matrices of Erdős-Renyi random graph. This is part of some earlier results joint with L. Tran and V. Vu.

Pulmonary surfactant is composed of phospholipids, neutral lipids and proteins. Surfactant's composition is important for its ability to reduce surface tensions within alveoli. Previous studies showed that serum‐protein mediated surfactant dysfunction can be overcome by the addition of surfactant protein A (SP‐A) to the material. Elevated cholesterol levels in surfactant can also cause surfactant dysfunction, but it is unknown if SP‐A can reverse this form of impairment. It was hypothesized that the addition of SP‐A to surfactant with elevated levels of cholesterol will improve the material's ability to reduce surface tension. Human surfactant was depleted of cholesterol via repeated acetone precipitation and reconstituted with 0, 5, 10 or 20% cholesterol with or without 5% SP‐A. The minimum achievable surface tension of the samples was tested on a captive bubble surfactometer. Results showed that surfactant with 10 and 20% cholesterol had significantly higher minimum surface tensions than surfactant with 0 and 5% cholesterol. Addition of SP‐A to samples with 10 and 20% cholesterol resulted in significantly lower minimum surface tension as compared to analogous samples without SP‐A. In conclusion, cholesterol mediated surfactant dysfunction can be mitigated by SP‐A. Funding was provided by Canadian Institutes for Health Research.

Consider N × N Hermitian or symmetric random matrices H with independent entries, where the distribution of the ( i , j ) matrix element is given by the probability measure ν i j with zero expectation and with variance σ i j 2 . We assume that the variances satisfy the normalization condition ∑ i σ i j 2 = 1 for all j and that there is a positive constant c such that c ⩽ N σ i j 2 ⩽ c − 1 . We further assume that the probability distributions ν i j have a uniform subexponential decay. We prove that the Stieltjes transform of the empirical eigenvalue distribution of H is given by the Wigner semicircle law uniformly up to the edges of the spectrum with an error of order ( N η ) − 1 where η is the imaginary part of the spectral parameter in the Stieltjes transform. There are three corollaries to this strong local semicircle law: (1) Rigidity of eigenvalues: If γ j = γ j , N denotes the classical location of the j-th eigenvalue under the semicircle law ordered in increasing order, then the j-th eigenvalue λ j is close to γ j in the sense that for some positive constants C, c P ( ∃ j : | λ j − γ j | ⩾ ( log N ) C log log N [ min ( j , N − j + 1 ) ] − 1 / 3 N − 2 / 3 ) ⩽ C exp [ − ( log N ) c log log N ] for N large enough. (2) The proof of Dysonʼs conjecture (Dyson, 1962 [15]) which states that the time scale of the Dyson Brownian motion to reach local equilibrium is of order N − 1 up to logarithmic corrections. (3) The edge universality holds in the sense that the probability distributions of the largest (and the smallest) eigenvalues of two generalized Wigner ensembles are the same in the large N limit provided that the second moments of the two ensembles are identical.

We consider $n\times n$ Hermitian matrices with i.i.d. entries $X_{ij}$ whose tail probabilities $\mathbb {P}(|X_{ij}|\geq t)$ behave like $e^{-at^{\alpha}}$ for some $a>0$ and $\alpha \in(0,2)$. We establish a large deviation principle for the empirical spectral measure of $X/\sqrt{n}$ with speed $n^{1+\alpha /2}$ with a good rate function $J(\mu)$ that is finite only if $\mu$ is of the form $\mu=\mu_{\mathrm{sc}}\boxplus\nu$ for some probability measure $\nu$ on $\mathbb {R}$, where $\boxplus$ denotes the free convolution and $\mu_{\mathrm{sc}}$ is Wigner's semicircle law. We obtain explicit expressions for $J(\mu_{\mathrm{sc}}\boxplus\nu)$ in terms of the $\alpha$th moment of $\nu$. The proof is based on the analysis of large deviations for the empirical distribution of very sparse random rooted networks.

The main objective of this paper is to analyse the composition of a sulphate-free binary or ternary surfactant system with alkyl olefin sulfonate (AOS), alkyl polyglucoside (APG) and lauryl hydroxysultaine (Sultaine). The composition was optimized by observing critical parameters such as surface activity and rheological properties while varying the concentration of APG in a ternary system, varying the ratio of AOS and Sultaine in a binary system and studying the effect of sodium chloride addition. The experimental results can provide an alternative, sulphate-free surfactant system to replace the common system containing sodium laureth sulfate (SLES) and cocamidopropyl betaine (CapB), without compromising on the parameters previously mentioned. A DuNouy Ring was utilized on a tensiometer to measure the surface tension of the samples. To observe foaming abilities of samples, a visual foaming study was conducted and recorded by taking pictures. A TA instruments mechanical rheometer was used to measure the viscosity. Studying the effect of APG concentration on surface tension illustrated that as APG concentration decreases, surface tension decreases as well. The minimum surface tension was found to be 26.587 for 7.5wt.% AOS and 7.5wt.% Sultaine. When the ratio between AOS and Sultaine changed, the 1:1system produced the lowest surface tension value again. As the concentration of AOS decreased in the ratio, the surface tension increased. When the ratio was held constant, and APG was introduced into the system, the systems containing APG had higher surface tension values compared with the systems with the same ratios but did not have APG added. As the concentration of salt increased, the surface tension decreased for AOS, increased for the binary mixture and had no effect on Sultaine. Foaming has a direct correlation with surface tension so a decrease in surface tension led to better foaming abilities; therefore, the 1:1 ratio of AOS:Sultaine had the best foaming qualities. The AOS/Sultaine system exhibited Maxwellian behaviour, suggesting the presence of worm-like micellar structures. As the concentration of APG increased, the viscosity decreased and at a concentration of 2.5wt.% AOS, 5wt.% APG and 7.5wt.% Sultaine, the system changed from shear thinning non-Newtonian fluid to Newtonian. Varying the ratio of AOS:Sultaine in the binary system, showed as the ratio changed, the viscosity decreased, and at a ratio of 1:3 AOS:Sultaine, the system was primarily Newtonian. As the ratio remained constant and APG was added, the viscosity continued to decrease and the 1:3 ratio was completely Newtonian. The addition of salt had no effect on the viscosity of Sultaine, but the viscosity of AOS increased at a salt concentration of 2wt.%. The binary mixture saw as the concentration of salt increased, the viscosity profile decreased, even though the system remained non-Newtonian and shear thinning. The surface activity and rheological study of the sulfate-free surfactant systems unveil a strong synergistic interaction between AOS and Sultaine specifically at a ratio of 1:1 resulting in high surface activity and corresponding good foaming and formation of entangled wormlike micelles resulting in excellent viscosity build in the system. If introducing a biobased surfactant into this system is desired without completely compromising the performance properties, the ternary surfactant system 4.5wt.% AOS, 3wt.% APG and 7.5wt.% Sultaine should be considered optimal. Any further addition of APG or changing the ratio results in detrimental reductions of all performance controlling physio-chemical parameters.

This study examined the effect of temperature on the surface activity of surface-modified silica nanoparticles’ dispersions. Silica nanoparticles were functionalized with hydrophobic n-propyl, n-hexyl, or n-octyl groups, as well as hydrophilic methoxy poly(ethylene glycol) groups, enabling regulation of their wettability. The nanoparticles’ ability to alter water surface tension was examined at various temperatures ranging from 20 to 70 ° C . The unmodified nanoparticle causes a slight modulation in surface tension, which shows insignificant dependence on nanoparticle concentration. As the temperature rises, the surface tension exhibits a linear decrease. The unmodified-silica nanofluid demonstrates a thermal dependence of surface tension closely resembling the behavior observed in double-distilled water. The surface-modified silica nanofluids exhibit a nonlinear dependence of surface tension on temperature. Nanoparticles comprising, at least, methoxy poly(ethylene glycol) groups display a surface tension minimum at the air–water interface. Two distinct regimes are observed for the thermal dependence of the surface tension. One is at temperatures less than surface-tension-minimum temperature, where the temperature significantly modulates the surface tension. The other regime is observed beyond the surface-tension-minimum temperature, where the temperature does not have much effect on the surface tension. Besides, the thermal stability of the nanoparticles was examined by aging the corresponding nanofluids at 60 ° C and monitoring the nanoparticles’ stability and surface properties according to a specified schedule. The nanoparticles’ stability and surface activity were found to diminish significantly with aging. • Effect of temperature on surface activity of surface-modified silica nanoparticles. • Nonlinear surface tension dependence on temperature for the surface-modified silica. • A surface tension minimum for nanoparticles with methoxy poly(ethylene glycol) groups. • The nanoparticles’ stability and surface activity diminish significantly with aging.

The present study characterizes the dynamic interfacial properties of calf lung surfactant (CLS) and samples reconstituted in a stepwise fashion from phospholipid (PL), hydrophobic apoprotein (HA), surfactant apoprotein A (SP-A), and neutral lipid fractions. Dipalmitoylphosphatidylcholine (DPPC), the major PL component of surfactant, was examined for comparison. Surface tension was measured over a range of oscillation frequencies (1-100 cycles/min) and bulk phase concentrations (0.01-1 mg/ml) by using a pulsating bubble surfactometer. Distinct differences in behavior were seen between samples. These differences were interpreted by using a previously validated model of surfactant adsorption kinetics that describes function in terms of 1) adsorption rate coefficient (k1), 2) desorption rate coefficient (k2), 3) minimum equilibrium surface tension (gamma*), 4) minimum surface tension at film collapse (gammamin), and 5) change in surface tension with interfacial area for gamma < gamma* (m2). Results show that DPPC and PL have k1 and k2 values several orders of magnitude lower than CLS. PL had a gammamin of 19-20 dyn/cm, significantly greater than CLS (nearly zero). Addition of the HA to PL restored dynamic interfacial behavior to nearly that of CLS. However, m2 remained at a reduced level. Addition of the SP-A to PL + HA restored m2 to a level similar to that of CLS. No further improvement in function occurred with the addition of the neutral lipid. These results support prior studies that show addition of HA to the PL markedly increases adsorption and film stability. However, SP-A is required to completely normalize dynamic behavior.

Maturation of fetal alveolar type II epithelial cells in utero is characterized by specific changes to lung surfactant phospholipids. Here, we quantified the effects of hormonal differentiation in vitro on the molecular specificity of cellular and secreted phospholipids from human fetal type II epithelial cells using electrospray ionization mass spectrometry. Differentiation, assessed by morphology and changes in gene expression, was accompanied by restricted and specific modifications to cell phospholipids, principally enrichments of shorter chain species of phosphatidylcholine (PC) and phosphatidylinositol, that were not observed in fetal lung fibroblasts. Treatment of differentiated epithelial cells with secretagogues stimulated the secretion of functional surfactant-containing surfactant proteins B and C (SP-B and SP-C). Secreted material was further enriched in this same set of phospholipid species but was characterized by increased contents of short-chain monounsaturated and disaturated species other than dipalmitoyl PC (PC16:0/16:0), principally palmitoylmyristoyl PC (PC16:0/14:0) and palmitoylpalmitoleoyl PC (PC16:0/16:1). Mixtures of these PC molecular species, phosphatidylglycerol, and SP-B and SP-C were functionally active and rapidly generated low surface tension on compression in a pulsating bubble surfactometer. These results suggest that hormonally differentiated human fetal type II cells do not select the molecular composition of surfactant phospholipid on the basis of saturation but, more likely, on the basis of acyl chain length.

The Gibbs adsorption equation is the thermodynamic cornerstone for the description and understanding of the surface tension in a surfactant solution. It relates the decrease in surface tension to an increased surfactant adsorption. In the early 1940s, it therefore puzzled researchers to sometimes observe a minimum in the surface tension for certain surfactant solutions, which seemed to indicate surfactant desorption (even depletion) according to the Gibbs adsorption equation. It is now understood that the minimum is related to contamination of the surfactant (notably by dodecanol), and its occurrence has since then been studied extensively in experiments. Still, the precise role of the (tiny amount of) contaminant present is not well understood and a quantitative description and understanding of the minimum in the experimental surface tension is lacking. It is the aim of the present article to provide such a quantitative description. Our theoretical analysis is based on a Statistical Thermodynamic treatment of the Langmuir model for a surfactant mixture combined with the mass action model adapted to describe the formation of mixed micelles. A new Statistical Thermodynamic expression for the surface tension is derived and used to compare with a number of surface tension experiments for both ionic and nonionic surfactant systems.

Numerous literature has been accumulated on the inter-face action or pulmonary surfactant material, however, only few papers are dealt with the physiological aspect of this material or inter-face action in asthmatic bronchitis. This communication is concerned with the alteration of the surfactant and interface action of the lung in experimentally induced asthmatic bronchitic condition in guinea pigs. The alteration of the interface action is quantitatively determined by the measurement of the phosphatidyl choline. The state of the anaphyractoid condition in asthmatic bronchitic change in passively sensitized and then locally desensitized guinea pigs had been clinically and anatomically observed.The lung wash solution which was obtained through airway was subjected for determining surface tension and quantitative determination of the phosphatidyl choline. The maximum surface tension and minimum surface tension were calibrated from the hysteresis curve, namely diagram of the surface tension and area ratio which was drawn by X-Y axis curve, being connected by modified wilhelmy balance which was widely used for determination of the interface action of the lung.The stability index was also caliculated from the given formula as follows :The phosphatidyl choline was purified from the specimen and identified by the two dimensional paper chromatography and semi-quantitative determination of this substance was performed.The results obtained were as follows :(1) Actively sensitized guinea pigs with airsole exposure of the antigen led to cause slight degree of anaphyractic state. In this circumstance, the lungs were edematous with overexpansion and presence of occasional hemorrhagic foci.On the other hand, local desensitized guinea pigs with repeated airsole exposure to the antigen turned out to be devoid of the anaphyractic reaction. The pathological findings of the lungs remained to be a lesser extent and were essentially identical with those of the control group.(2) The elevation of the maximum and minimum surface tension was observed in the passively sensitized guinea pigs and contrary, locally desensitized guinea pigs with repeated airsole exposure to the antigen remained in normal range as of the control group. As the matter of fact, the stability index was lowered in the former group and returned to the range of the control group.(3) The semi-quantitative determination of the phosphatidyl choline disclosed decrease in the former group and increase to the normal range as of the control group respectively. Therefore, it is postulated that the pulmonary surface tension is elevated at the sequence of the repeated attacks of the asthmatic condition and is lowered at recovery from the state. It is also reasonable to assume the alteration of the pulmonary surface tension is based on the quantitative changes of the pulmonary surfactant.

Pulmonary surfactant is a mixture of 85% phospholipids, 5–8% cholesterol and 5–8% surfactant proteins which forms a surface tension reducing lipid film at the air‐liquid interface of the alveoli. By reducing the surface tension to near 0mN/m values during compression (i.e. exhalation) surfactant maintains alveolar stability at low lung volumes and maintains proper lung compliance. The importance of surfactant is evident in Acute Respiratory Distress Syndrome (ARDS) in which the dysfunction of surfactant contributes to hypoxemia, regional areas of collapse and reduced lung compliance. Specifically, serum proteins, such as Albumin, leaking into the lung during ARDS have been shown to interfere with surfactant's ability to reach low surface tension. In addition, recent studies suggest that elevated cholesterol within surfactant also contribute to surfactant dysfunction in the setting of lung injury. Although the effects of cholesterol and serum proteins with surfactant have been studied independently, the interaction between the two has not previously been investigated. It was hypothesized that elevated levels of cholesterol within surfactant will make surfactant more susceptible to serum protein inhibition.MethodsBovine Lipid Extract Surfactant (BLES), a commercially available exogenous surfactant, was utilized and modified to generate samples with concentrations of 0, 2.5, 5 and 10% (w/w) cholesterol. Varying amounts of Bovine Serum Albumin (BSA) were subsequently added to each sample to attain concentrations of 0, 20, 30, 40 and 50 mg/ml. A constrained sessile drop surfactometer was used to determine the minimal achievable surface tensions during dynamic compression/expansion cycles.ResultsSamples with various levels of cholesterol, in the absence of BSA, reached minimum surface tension values of near 0mN/m during compression. At moderate levels of BSA (20 &amp; 30mg/ml), minimum surface tensions were lower in surfactant samples containing cholesterol as compared to samples containing no cholesterol. Finally, at high BSA values, all surfactant samples had surface tension values that were higher than those at the lower BSA concentration but were not significantly different among the sample with different cholesterol concentrations.DiscussionContrary to the hypothesis, values of up to 10% cholesterol within surfactant do not appear to increase the susceptibility of surfactant to serum protein inhibition. In fact, the results suggest that cholesterol mitigates the effect of moderate levels of BSA on surfactant function. It is concluded that cholesterol within surfactant contributes to its resistance against inhibition by albumin.Support or Funding InformationCanadian Institutes for Health Research.

Bacteria produce a variety of biosurfactants capable of significantly reducing liquid (aqueous) surface tension (γ) with a range of biological roles and biotechnological uses. To determine the lowest achievable surface tension (γMin ), we tested a diverse collection of Pseudomonas-like isolates from contaminated soil and activated sludge and identified those expressing biosurfactants by drop-collapse assay. Liquid surface tension-reducing ability was quantitatively determined by tensiometry, with 57 isolates found to significantly lower culture supernatant surface tensions to 24·5-49·1mNm(-1) . Differences in biosurfactant behaviour determined by foaming, emulsion and oil-displacement assays were also observed amongst isolates producing surface tensions of 25-27mNm(-1) , suggesting that a range of structurally diverse biosurfactants were being expressed. Individual distribution identification (IDI) analysis was used to identify the theoretical probability distribution that best fitted the surface tension data, which predicted a γMin of 24·24mNm(-1) . This was in agreement with predictions based on earlier work of published mixed bacterial spp. data, suggesting a fundamental limit to the ability of bacterial biosurfactants to reduce surface tensions in aqueous systems. This implies a biological restriction on the synthesis and export of these agents or a physical-chemical restriction on their functioning once produced. Numerous surveys of biosurfactant-producing bacteria have been conducted, but only recently has an attempt been made to predict the minimum liquid surface tension these surface-active agents can achieve. Here, we determine a theoretical minimum of 24mNm(-1) by statistical analysis of tensiometry data, suggesting a fundamental limit for biosurfactant activity in bacterial cultures incubated under standard growth conditions. This raises a challenge to our understanding of biosurfactant expression, secretion and function, as well as being of interest to biotechnology where they are used in an increasingly wide range of applications.