Self-assembly of model short triblock amphiphiles in dilute solution

In this work, a molecular theory is used to study the self-assembly of short diblock and triblock amphiphiles, with head-tail and head-linker-tail structures, respectively. The theory was used to systematically explore the effects of the molecular architecture and the affinity of the solvent for the linker and tail blocks on the relative stability of the different nanostructures formed by the amphiphiles in dilute solution, which include spherical micelles, cylindrical fibers and planar lamellas. Moreover, the theory predicts that each of these nanostructures can adopt two different types of internal organization: (i) normal nanostructures with a core composed of tail segments and a corona composed of head segments, and (ii) nanostructures with a core formed by linker segments and a corona formed by tail and head segments. The theory predicts the occurrence of a transition from micelle to fiber to lamella when increasing the length of the tail or the linker blocks, which is in qualitative agreement with the geometric packing theory and with experiments in the literature. The theory also predicts a transition from micelle to fiber to lamella as the affinity of the solvent for the tail or linker block is decreased. This result is also in qualitative agreement with experiments in the literature but cannot be explained in terms of the geometric packing theory. The molecular theory provides an explanation for this result in terms of the competition between solvophobic attractions among segments in the core and steric repulsions between segments in the corona for the different types of self-assembled nanostructures.Fil: Zaldivar, Gervasio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Samad, M. B.. University of Nebraska; Estados UnidosFil: Conda Sheridan, Martin. University of Nebraska; Estados UnidosFil: Tagliazucchi, Mario Eugenio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentin

PERFORMANCE OF SPECIES Mabea fistulifera AND Eucalyptus urograndis WITH USE OF CELLULOSE RESIDUE IN DEGRADED AREAS

The planting of forest species contributes to the recovery of degraded areas, and the use of industrial waste can favor this process. However, there is still little information on this aspect in Cerrado. The objective of this work was to evaluate the performance of seedlings of the native species Mabea fistulifera Mart. and of the exotic hybrid Eucalyptus urograndis, under fertilization with residue of the industrial production of cellulose, in monospecific plantations in degraded area. Fertilization treatments, applied in the planting line, were three doses of the residue (10, 15 and 20 Mg ha -1); conventional mineral fertilizer (NPK); absence of fertilization (control). The experimental design was a randomized block design, with a portion of subdivided parts: species in the portions (15 m x 60 m, n = 4 / species) and treatments in the subportions (15 m x 12 m, n = 1 / treatment / portion) total of 18 plants in each subplot. Survival rate and growth attributes (height, crown diameter, stem diameter at ground level) were evaluated for two consecutive years. The largest increases in seedling survival and growth of both species were provided by mineral fertilization, followed by the 10 Mg ha -1 dose of the residue, which should be the recommended

Self-Assembled Nanostructures of Peptide Amphiphiles: Charge Regulation by Size Regulation

Self-assembled nanostructures of peptide amphiphiles (PAs) with molecular structures C16K2 and C16K3 (where C indicates the number of carbon atoms in the alkyl chain and K is the lysine in the head group) were studied by a combination of theoretical modeling, transmission electron and atomic force microscopes, and acid-base titration experiments. The supramolecular morphology of the PAs (micelles, fibers, or lamellas) was dependent on the pH and ionic strength of the solution. Theoretical modeling was performed using a molecular theory that allows determining the equilibrium morphology, the size, and the charge of the soft nanoassemblies as a function of the molecular structure of the PA, and the pH and salt concentration of the solution. Theoretical predictions showed good agreement with experimental data for the pH-dependent morphology and size of the nanoassemblies and their apparent pKa's. Two interesting effects associated with charge regulation mechanisms were found: first, ionic strength plays a dual role in the modulation of the electrostatic interactions in the system, which leads to complex dependencies of the aggregation numbers with salt concentration; second, the aggregation number of the nanostructures decreases upon increasing the charge per PA. The second mechanism, charge regulation by size regulation, tunes the net charge of the assemblies to decrease the electrostatic repulsions. A remarkable consequence of this behavior is that adding an extra lysine residue to the charged region of the PAs can lead to an unexpected decrease in the total charge of the micelles.Fil: Zaldivar, Gervasio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Vemulapalli, Sridhar. University Of Nebraska Medical Center; Estados UnidosFil: Udumula, Venkatareddy. University Of Nebraska Medical Center; Estados UnidosFil: Conda Sheridan, Martin. University Of Nebraska Medical Center; Estados UnidosFil: Tagliazucchi, Mario Eugenio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentin

The spectrograph: a prototype for a digital spectrometer

Optical spectroscopy is a conceptual referent which links classical and modern Physics. This paper will consider how an educational path has to involve students in interpretative activities. Experiments can allow one to highlight the link between energy levels in atoms and discrete light emissions. After analysing several commercial devices and apps for mobile devices, our Physics Education Research Unit from Udine University (Italy) designed and created a digital spectrometer using a simple webcam and implemented the various functionalities which can be connected to PCs via USBs. Both hardware and software have been designed in order to obtain spectral images of various sources and the digitised spectrum. The hardware allows the use of different diffraction grating, coloured and optical filters and an optical goniometer, whilst the software is designed to allow calibration and qualitative and quantitative measures of wavelengths. We will describe this system in detail as well as some experimental activities which can be carried out by secondary school students and freshmen in biotechnology.peer-reviewe

Conformal Electrodeposition of Antimicrobial Hydrogels Formed by Self-Assembled Peptide Amphiphiles

The colonization of biomedical surfaces by bacterial biofilms is concerning because these microorganisms display higher antimicrobial resistance in biofilms than in liquid cultures. Developing antimicrobial coatings that can be easily applied to medically-relevant complex-shaped objects, such as implants and surgical instruments, is an important and challenging research direction. This work reports the preparation of antibacterial surfaces via the electrodeposition of a conformal hydrogel of self-assembling cationic peptide-amphiphiles (PAs). Hydrogels of three PAs are electrodeposited: C16K2, C16K3, and C18K2, where Cn is an alkyl chain of n methylene groups and Km is an oligopeptide of m lysines. The processing variables (electrodeposition time, potential, pH, salt concentration, agitation) enable fine control of film thickness, demonstrating the flexibility of the method and allowing to unravel the mechanisms underlying electrodeposition. The electrochemically prepared hydrogels inhibit the growth of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa in agar plates, and prevent the formation of biofilms of Acinetobacter baumannii and P. aeruginosa and the formation of A. baumannii colonies in solid media. C16K2 and C16K3 hydrogels outperform the antimicrobial activity of those of C18K2 while maintaining good compatibility with human cells

Investigation With Large-eddy Simulation of the Sea Breeze Regimes

Neste trabalho, investigam-se as interações entre a brisa marítima e a turbulência sobre a Terra empregando uma simulação dos grandes turbilhões (LES). Os resultados mostram que o modelo LES é capaz de similar um regime de brisa Mar-Terra-Mar

Structure of the connexin-43 gap junction channel in a putative closed state

Gap junction channels (GJCs) mediate intercellular communication by connecting two neighbouring cells and enabling direct exchange of ions and small molecules. Cell coupling via connexin-43 (Cx43) GJCs is important in a wide range of cellular processes in health and disease (Churko and Laird, 2013; Liang et al., 2020; Poelzing and Rosenbaum, 2004), yet the structural basis of Cx43 function and regulation has not been determined until now. Here, we describe the structure of a human Cx43 GJC solved by cryo-EM and single particle analysis at 2.26 Å resolution. The pore region of Cx43 GJC features several lipid-like densities per Cx43 monomer, located close to a putative lateral access site at the monomer boundary. We found a previously undescribed conformation on the cytosolic side of the pore, formed by the N-terminal domain and the transmembrane helix 2 of Cx43 and stabilized by a small molecule. Structures of the Cx43 GJC and hemichannels (HCs) in nanodiscs reveal a similar gate arrangement. The features of the Cx43 GJC and HC cryo-EM maps and the channel properties revealed by molecular dynamics simulations suggest that the captured states of Cx43 are consistent with a closed state

Base de Información Bioantropológica de Patagonia Austral (B.I.B.P.A)

The human skeletal remains of Southern Patagonia are scattered throughout numerous European and American institutions. Currently there are more than 1150 individuals in those institutions. Information about the remains and the peer-reviewed published bioanthropological information about each of them have been compiled in the Base de Información Bioantropológica de Patagonia Austral (Southern Patagonian Bioanthropological Information Base). This platform is conceived as a tool that seeks to facilitate and streamline the work of the community of bioanthropologists and other scientists. The database is public and open source, and it is available to both the scientific community and the wider public. It will be updated periodically, with the information that the community generates and makes available to its peers by meansof the various formats that scientists employ to publish their scientific work.Los restos óseos humanos de Patagonia Austral se encuentran dispersos en numerosas instituciones europeas y americanas. Actualmente se contabilizan más de 1150 individuos. Esos sujetos y la información de orden bioantropológica publicada acerca de cada uno de ellos ha sido compilada en la Base de Información Bioantropológica de Patagonia Austral. Esta plataforma se concibe como una herramienta que busca facilitar y agilizar la labor de la comunidad de antropólogos biólogos y afines, de la región. Es de carácter público y código abierto, y se encuentra a disposición tanto de la comunidad científica como de la sociedad. Se actualizará de manera periódica, con la información que la comunidad genere y ponga a disposición de sus pares a través de los diversos formatos que los científicos tienen para difundir su labor científica

Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

Penilaian Kinerja Keuangan Koperasi di Kabupaten Pelalawan

This paper describe development and financial performance of cooperative in District Pelalawan among 2007 - 2008. Studies on primary and secondary cooperative in 12 sub-districts. Method in this stady use performance measuring of productivity, efficiency, growth, liquidity, and solvability of cooperative. Productivity of cooperative in Pelalawan was highly but efficiency still low. Profit and income were highly, even liquidity of cooperative very high, and solvability was good