Chiral and herringbone symmetry breaking in water-surface monolayers

We report the observation from monolayers of eicosanoic acid in the L′2 phase of three distinct out-of-plane first-order diffraction peaks, indicating molecular tilt in a nonsymmetry direction and hence the absence of mirror symmetry. At lower pressures the molecules tilt in the direction of their nearest neighbors. In this region we find a structural transition, which we tentatively identify as the rotator-herringbone transition L2d−L2h

Density-functional theory of elastically deformed finite metallic system: work function and surface stress

The effect of external strain on surface properties of simple metals is considered within the modified stabilized jellium model. The equations for the stabilization energy of the deformed Wigner-Seitz cells are derived as a function of the bulk electron density and the given deformation. The results for surface stress and work function of aluminium calculated within the self-consistent Kohn-Sham method are also given. The problem of anisotropy of the work function of finite system is discussed. A clear explanation of independent experiments on stress-induced contact potential difference at metal surfaces is presented.Comment: 15 pages, 1 figur

Morphology selection of nanoparticle dispersions by polymer media

A systematic theory of ultrathin polymer films as organizing media to achieve 2D nanoparticle arrangements was developed. The key physical variables to achieve nanoparticle dispersions and control morphology were determined.open727

Upcycling spent brewery grains through the production of carbon adsorbents: application to the removal of carbamazepine from water

Spent brewery grains, a by-product of the brewing process, were used as precursor of biochars and activated carbons to be applied to the removal of pharmaceuticals from water. Biochars were obtained by pyrolysis of the raw materials, while activated carbons were produced by adding a previous chemical activation step. The influence of using different precursors (from distinct fermentation processes), activating agents (potassium hydroxide, sodium hydroxide, and phosphoric acid), pyrolysis temperatures, and residence times was assessed. The adsorbents were physicochemically characterized and applied to the removal of the antiepileptic carbamazepine from water. Potassium hydroxide activation produced the materials with the most promising properties and adsorptive removals, with specific surface areas up to 1120 m2 g-1 and maximum adsorption capacities up to 190 ± 27 mg g-1 in ultrapure water. The adsorption capacity suffered a reduction of < 70% in wastewater, allowing to evaluate the impact of realistic matrices on the efficiency of the materials.publishe

Behavior and Impact of Zirconium in the Soil–Plant System: Plant Uptake and Phytotoxicity

Because of the large number of sites they pollute, toxic metals that contaminate terrestrial ecosystems are increasingly of environmental and sanitary concern (Uzu et al. 2010, 2011; Shahid et al. 2011a, b, 2012a). Among such metals is zirconium (Zr), which has the atomic number 40 and is a transition metal that resembles titanium in physical and chemical properties (Zaccone et al. 2008). Zr is widely used in many chemical industry processes and in nuclear reactors (Sandoval et al. 2011; Kamal et al. 2011), owing to its useful properties like hardness, corrosion-resistance and permeable to neutrons (Mushtaq 2012). Hence, the recent increased use of Zr by industry, and the occurrence of the Chernobyl and Fukashima catastrophe have enhanced environmental levels in soil and waters (Yirchenko and Agapkina 1993; Mosulishvili et al. 1994 ; Kruglov et al. 1996)

Detection of autoantibodies against reactive oxygen species modified glutamic acid decarboxylase-65 in type 1 diabetes associated complications

<p>Abstract</p> <p>Background</p> <p>Autoantibodies against glutamate decarboxylase-65 (GAD₆₅Abs) are thought to be a major immunological tool involved in pathogenic autoimmunity development in various diseases. GAD₆₅Abs are a sensitive and specific marker for type 1 diabetes (T1D). These autoantibodies can also be found in 6-10% of patients classified with type 2 diabetes (T2D), as well as in 1-2% of the healthy population. The latter individuals are at low risk of developing T1D because the prevalence rate of GAD₆₅Abs is only about 0.3%. It has, therefore, been suggested that the antibody binding to GAD₆₅in these three different GAD₆₅Ab-positive phenotypes differ with respect to epitope specificity. The specificity of reactive oxygen species modified GAD₆₅(ROS-GAD₆₅) is already well established in the T1D. However, its association in secondary complications of T1D has not yet been ascertained. Hence this study focuses on identification of autoantibodies against ROS-GAD₆₅(ROS-GAD₆₅Abs) and quantitative assays in T1D associated complications.</p> <p>Results</p> <p>From the cohort of samples, serum autoantibodies from T1D retinopathic and nephropathic patients showed high recognition of ROS-GAD₆₅as compared to native GAD₆₅(N-GAD₆₅). Uncomplicated T1D subjects also exhibited reactivity towards ROS-GAD₆₅. However, this was found to be less as compared to the binding recorded from complicated subjects. These results were further proven by competitive ELISA estimations. The apparent association constants (AAC) indicate greater affinity of IgG from retinopathic T1D patients (1.90 × 10^-6M) followed by nephropathic (1.81 × 10^-6M) and uncomplicated (3.11 × 10^-7M) T1D patients for ROS-GAD₆₅compared to N-GAD₆₅.</p> <p>Conclusion</p> <p>Increased oxidative stress and blood glucose levels with extended duration of disease in complicated T1D could be responsible for the gradual formation and/or exposing cryptic epitopes on GAD₆₅that induce increased production of ROS-GAD₆₅Abs. Hence regulation of ROS-GAD₆₅Abs could offer novel tools for analysing and possibly treating T1D complications.</p

Active microrheology and simultaneous visualization of sheared phospholipid monolayers

Two-dimensional films of surface-active agents—from phospholipids and proteins to nanoparticles and colloids—stabilize fluid interfaces, which are essential to the science, technology and engineering of everyday life. The 2D nature of interfaces present unique challenges and opportunities: coupling between the 2D films and the bulk fluids complicates the measurement of surface dynamic properties, but allows the interfacial microstructure to be directly visualized during deformation. Here we present a novel technique that combines active microrheology with fluorescence microscopy to visualize fluid interfaces as they deform under applied stress, allowing structure and rheology to be correlated on the micron-scale in monolayer films. We show that even simple, single-component lipid monolayers can exhibit viscoelasticity, history dependence, a yield stress and hours-long time scales for elastic recoil and aging. Simultaneous visualization of the monolayer under stress shows that the rich dynamical response results from the cooperative dynamics and deformation of liquid-crystalline domains and their boundaries

Molecular fluorescence above metallic gratings

P. Andrew and William L. Barnes, Physical Review B, Vol. 64, article 125405 (2001). "Copyright © 2001 by the American Physical Society."We present measurements of the fluorescence of emitters located in close proximity (d<λ) to metallic grating surfaces. By measuring both the spontaneous emission lifetime and angle-dependent radiation pattern of a monolayer of dye molecules as a function of their separation from planar and periodically corrugated mirrors of increasing modulation depth, we are able to examine the effect of varying the surface profile on the emission process. Both the distance dependence of the lifetime and the spatial distribution of the emitted light are significantly changed upon the introduction of a corrugation, quite apart from the appearance of the familiar Bragg-scattered bound-mode features. It is postulated that these perturbations arise from the interference of the grating scattered dipole fields with the usual upward propagating and reflected fields. In addition, the measurement of nonexponential decay transients for the deepest gratings examined provide evidence for the existence of optically dissimilar dipole positions above the grating surface