Salt-induced reentrant stability of polyion-decorated particles with tunable surface charge density

The electrostatic complexation between DOTAP-DOPC unilamellar liposomes and an oppositely charged polyelectrolyte (NaPA) has been investigated in a wide range of the liposome surface charge density. We systematically characterized the "reentrant condensation" and the charge inversion of polyelectrolyte-decorated liposomes by means of dynamic light scattering and electrophoresis. We explored the stability of this model polyelectrolyte/colloid system by fixing each time the charge of the bare liposomes and by changing two independent control parameters of the suspensions: the polyelectrolyte/colloid charge ratio and the ionic strength of the aqueous suspending medium. The progressive addition of neutral DOPC lipid within the liposome membrane gave rise to a new intriguing phenomenon: the stability diagram of the suspensions showed a novel reentrance due to the crossing of the desorption threshold of the polyelectrolyte. Indeed, at fixed charge density of the bare DOTAP/DOPC liposomes and for a wide range of polyion concentrations, we showed that the simple electrolyte addition first (low salt regime) destabilizes the suspensions because of the enhanced screening of the residual repulsion between the complexes, and then (high salt regime) determines the onset of a new stable phase, originated by the absence of polyelectrolyte adsorption on the particle surfaces. We show that the observed phenomenology can be rationalized within the Velegol-Thwar model for heterogeneously charged particles and that the polyelectrolyte desorption fits well the predictions of the adsorption theory of Winkler and Cherstvy. Our findings unambiguously support the picture of the reentrant condensation as driven by the correlated adsorption of the polyelectrolyte chains on the particle surface, providing interesting insights into possible mechanisms for tailoring complex colloids via salt-induced effects.Comment: 34 pages, 7 figure

Resonant Spin Hall Effect of Light in Random Photonic Arrays

It has been recently shown that the coherent component of light propagating in transversally disordered media exhibits an analogue spin Hall effect (SHE). In non-resonant materials, however, the SHE shows up at a scale much larger than the mean free path, making its observation challenging due to the exponential attenuation of the coherent mode. Here, we show that in disordered photonic arrays, the SHE on the contrary appears at a scale smaller than the mean free path if one operates in the close vicinity of the second, transverse-magnetic Mie resonance of the array. In combination with a weak measurement, this gives rise to a giant SHE visible in optically-thin arrays. Furthermore, we find that by additionally exploiting the coherent flash of light following the abrupt extinction of the incoming beam, one can achieve a time-dependent SHE, observable at large optical thickness as well.Comment: 25 page

Climate , wind energy, and CO2 emissions from energy production in Denmark

The dynamic relation between CO2 emissions and wind energy in Denmark is analyzed using a fractional cointegration approach, extended to accommodate covariates. The impact of climate and forces of demand on the potential of wind power production for emissions abatement is investigated. Emissions decline as temperature increases. Wind power production increases with precipitation and North Atlantic oscillations. Aggregate output matters for emissions in a manner consistent with an environmental Kuznets curve (EKC). Accounting for a seasonal trend, our main estimate of marginal CO2 emissions avoided (MEA) per MWh of wind energy produced is 0.16 tonnes, based on impulse responses. This estimate of the abatement potential of wind power is lower than values reported in the literature, but statistically significant, and robust to including climate and EKC variables. MEA is reduced by about one third by treating electricity prices as endogenous, and by one quarter by including emissions from combustion of biomass. However, formal exogeneity tests indicate that the main MEA estimate is not inflated due to left-out general equilibrium effects. Without covariates, estimated MEA is 0.07, and insignificant

Herpetofauna del Delta del río Paraná en la provincia de Buenos Aires

Desde el punto de vista zoogeográfico, el Delta del río Paraná en la provincia de Buenos Aires se encuentra en medio de una serie de corrientes de dispersión faunística de diversa naturaleza (Kandus y Malvárez, 2002; Quintana et al., 2002; Giraudo et al., 2004). Dicha región se emplaza en la Ecorregión Delta e Islas del Paraná (Burkart et al. 1999). Se trata de un importante conjunto de islas surcadas por numerosos cursos de agua y formado por sedimentos transportados por el río Paraná. La elevada heterogeneidad ambiental, producto de procesos geológicos pasados y actuales, así como sus particularidades climáticas, determinan diferentes paisajes habitados por una diversa biota (Bó, 2005). En el caso de la herpetofauna, en la zona coexisten especies de las regiones Chaco-Pampeana y Litoral-Mesopotámica. Muchas de éstas especies ingresan y se distribuyen en la región durante las grandes inundaciones (Kandus et al., 2006). De hecho, el Delta del Paraná presenta una importante diversidad específica de reptiles y anfibios, abarcando más del 80% de las especies conocidas para la provincia de Buenos Aires (Williams, 1991). En contraposición con su gran diversidad específica y ecológica, la herpetofauna del Delta del Paraná en Buenos Aires permanece aún pobremente conocida; los relevamientos son escasos y la información con respecto a las especies continúa dispersa. El objetivo del presente trabajo es el de brindar un panorama actualizado que incluya la totalidad de las citas previas encontradas de las especies de anfibios y reptiles para la región, así como las localidades y áreas protegidas para las cuales han sido citadas.Instituto de Limnología "Dr. Raúl A. Ringuelet

Model-Based Identification of Alternative Bidding Zones: Applications of Clustering Algorithms with Topology Constraints

The definition of bidding zones is a relevant question for electricity markets. The bidding zones can be identified starting from information on the nodal prices and network topology, considering the operational conditions that may lead to congestion of the transmission lines. A well-designed bidding zone configuration is a key milestone for an efficient market design and a secure power system operation, being the basis for capacity allocation and congestion management processes, as acknowledged in the relevant European regulation. Alternative bidding zone configurations can be identified in a process assisted by the application of clustering methods, which use a predefined set of features, objectives and constraints to determine the partitioning of the network nodes into groups. These groups are then analysed and validated to become candidate bidding zones. The content of the manuscript can be summarized as follows: (1) A novel probabilistic multi-scenario methodology was adopted. The approach needs the analysis of features that are computed considering a set of scenarios defined from solutions in normal operation and in planned maintenance cases. The weights of the scenarios are indicated by TSOs on the basis of the expected frequency of occurrence; (2) The relevant features considered are the Locational Marginal Prices (LMPs) and the Power Transfer Distribution Factors (PTDFs); (3) An innovative computation procedure based on clustering algorithms was developed to group nodes of the transmission electrical network into bidding zones considering topological constraints. Several settings and clustering algorithms were tested in order to evaluate the robustness of the identified solution

A systematic study of the valence electronic structure of cyclo(Gly–Phe), cyclo(Trp–Tyr) and cyclo(Trp–Trp) dipeptides in the gas phase

The electronic energy levels of cyclo(glycine–phenylalanine), cyclo(tryptophan–tyrosine) and cyclo(tryptophan–tryptophan) dipeptides are investigated with a joint experimental and theoretical approach. Experimentally, valence photoelectron spectra in the gas phase are measured using VUV radiation. Theoretically, we first obtain low-energy conformers through an automated conformer–rotamer ensemble sampling scheme based on tight-binding simulations. Then, different first principles computational schemes are considered to simulate the spectra: Hartree–Fock (HF), density functional theory (DFT) within the B3LYP approximation, the quasi-particle GW correction, and the quantumchemistry CCSD method. Theory allows assignment of the main features of the spectra. A discussion on the role of electronic correlation is provided, by comparing computationally cheaper DFT scheme (and GW) results with the accurate CCSD method

Electron and ion spectroscopy of Azobenzene in the valence and core shells

Azobenzene is a prototype and building block of a class of molecules of extreme technological interest as molecularphoto-switches. We present a joint experimental and theoretical study of its response to irradiation with light across theUV to X-ray spectrum. The study of valence and inner shell photo-ionization and excitation processes, combined withmeasurement of valence photoelectron-photoion coincidence (PEPICO) and of mass spectra across the core thresholdsprovides a detailed insight onto the site- and state-selected photo-induced processes. Photo-ionization and excita-tion measurements are interpreted via the multi-configurational restricted active space self-consistent field (RASSCF)method corrected by second order perturbation theory (RASPT2). Using static modelling, we demonstrate that thecarbon and nitrogen K edges of Azobenzene are suitable candidates for exploring its photoinduced dynamics thanks tothe transient signals appearing in background-free regions of the NEXAFS and XP

An integrated approach to the evaluation of patients with asymptomatic or minimally symptomatic hyperCKemia

INTRODUCTION/AIMS: Currently, there are no straightforward guidelines for the clinical and diagnostic management of hyperCKemia, a frequent and nonspecific presentation in muscle diseases. Therefore, we aimed to describe our diagnostic workflow for evaluating patients with this condition. METHODS: We selected 83 asymptomatic or minimally symptomatic patients with persistent hyperCKemia for participation in this Italian multicenter study. Patients with facial involvement and distal or congenital myopathies were excluded, as were patients with suspected inflammatory myopathies or predominant respiratory or cardiac involvement. All patients underwent a neurological examination and nerve conduction and electromyography studies. The first step of the investigation included a screening for Pompe disease. We then evaluated the patients for myotonic dystrophy type II–related CCTG expansion and excluded patients with copy number variations in the DMD gene. Subsequently, the undiagnosed patients were investigated using a target gene panel that included 20 genes associated with isolated hyperCKemia. RESULTS: Using this approach, we established a definitive diagnosis in one third of the patients. The detection rate was higher in patients with severe hyperCKemia and abnormal electromyographic findings. DISCUSSION: We have described our diagnostic workflow for isolated hyperCKemia, which is based on electrodiagnostic data, biochemical screening, and first‐line genetic investigations, followed by successive targeted sequencing panels. Both clinical signs and electromyographic abnormalities are associated with increased diagnostic yields

Three-row versus two-row circular staplers for left-sided colorectal anastomosis: a propensity score-matched analysis of the iCral 2 and 3 prospective cohorts

Background: Since most anastomoses after left-sided colorectal resections are performed with a circular stapler, any technological change in stapling devices may influence the incidence of anastomotic adverse events. The aim of the present study was to analyze the effect of a three-row circular stapler on anastomotic leakage and related morbidity after left-sided colorectal resections. Materials and methods: A circular stapled anastomosis was performed in 4255 (50.9%) out of 8359 patients enrolled in two prospective multicenter studies in Italy, and, after exclusion criteria to reduce heterogeneity, 2799 (65.8%) cases were retrospectively analyzed through a 1:1 propensity score-matching model including 20 covariates relative to patient characteristics, to surgery and to perioperative management. Two well-balanced groups of 425 patients each were obtained: group (A) – true population of interest, anastomosis performed with a three-row circular stapler; group (B) – control population, anastomosis performed with a two-row circular stapler. The target of inferences was the average treatment effect in the treated (ATT). The primary endpoints were overall and major anastomotic leakage and overall anastomotic bleeding; the secondary endpoints were overall and major morbidity and mortality rates. The results of multiple logistic regression analyses for the outcomes, including the 20 covariates selected for matching, were presented as odds ratios (OR) and 95% confidence intervals (95% CI). Results: Group A versus group B showed a significantly lower risk of overall anastomotic leakage (2.1 vs. 6.1%; OR 0.33; 95% CI 0.15–0.73; P = 0.006), major anastomotic leakage (2.1 vs. 5.2%; OR 0.39; 95% CI 0.17–0.87; P = 0.022), and major morbidity (3.5 vs. 6.6% events; OR 0.47; 95% CI 0.24–0.91; P = 0.026). Conclusion: The use of three-row circular staplers independently reduced the risk of anastomotic leakage and related morbidity after left-sided colorectal resection. Twenty-five patients were required to avoid one leakage