Nanocellulose Fragmentation Mechanisms and Inversion of Chirality from the Single Particle to the Cholesteric Phase

Understanding how nanostructure and nanomechanics influence physical material properties on the micro- and macroscale is an essential goal in soft condensed matter research. Mechanisms governing fragmentation and chirality inversion of filamentous colloids are of specific interest because of their critical role in load-bearing and self-organizing functionalities of soft nanomaterials. Here we provide a fundamental insight into the self-organization across several length scales of nanocellulose, an important bio-colloid system with wide-ranging applications as structural, insulating and functional material. Through a combined microscopic and statistical analysis of nanocellulose fibrils at the single particle level, we show how mechanically and chemically induced fragmentation proceed in this system. Moreover, by studying the bottom-up self-assembly of fragmented carboxylated cellulose nanofibrils into cholesteric liquid crystals, we show via direct microscopic observations, that the chirality is inverted from right-handed at the nanofibril level to left-handed at the level of the liquid crystal phase. These results improve our fundamental understanding of nanocellulose and provide an important rationale for their application in colloidal systems, liquid crystals and nanomaterials

On Choosing an Exchange Rate Regimes in Emerging Economies

This paper discusses that a lot of the debate on selecting an exchange rate regime misses the time. It begins explaining the standard theory of choice between exchange rate regimes, and then explores the fragilities in this theory, specifically when this is applied to emerging economies. Next presents a extent of institutional characteristics that might have influence upon a country to choose either fixed or floating rates , and then turns to the converse question of whether the selection of exchange rate regime may make for the development of some helpful institutional traits. The conclusion is that the election of exchange rate regime is likely to be of second order significance to the development of good fiscal, financial, and monetary institutions in causing macroeconomic achievement in emerging market. A greater dedication in strong institution's development instead of focalizing in the exchange rate regimes could make economies healthier and less propense to the crises, as was observed of late years.Regimenes de Tipo de Cambio; Economias Emergentes; Inflacion;Currency Board; Soft Pegs; Hard Pegs

Globalization Effect on both Inflation and Domestic Monetary Policy

This paper discusses that many of the exaggerated claims that globalization has been an important element in the reduction of the inflation in the recent years do not come true. The globalization has, however, the potential to contribute to the stabilization of economies and this has been crucial element in promoting the growth of economies. The paper, therefore, analyzes four issues on the impact of the globalization upon the mechanisms of monetary transmission and arrives at the following findings. ( 1 ) Globalization did not reduce the sensibility of inflation to the domestic production gaps and in consequence to the effectiveness of the monetary policy,. ( 2 ) Gaps in the product of external economies do not play a more important role than in other times,.( 3 ) Domestic monetary policy maintains still the control on the domestic interest rates and that way pursuing the stabilization of inflation and the product,.( 4 ) Globalization affects, by means of different forms, the mechanisms of monetary transmissionGlobalizacion; Inflacion; Politica Monetaria

Modulating self-assembly of a nanotape-forming peptide amphiphile with an oppositely charged surfactant

A peptide amphiphile (PA) C16-KTTKS, containing a pentapeptide headgroup based on a sequence from procollagen I attached to a hexadecyl lipid chain, self-assembles into extended nanotapes in aqueous solution. The tapes are based on bilayer structures, with a 5.2 nm spacing. Here, we investigate the effect of addition of the oppositely charged anionic surfactant sodium dodecyl sulfate (SDS) via AFM, electron microscopic methods, small-angle X-ray scattering and X-ray diffraction among other methods. We show that addition of SDS leads to a transition from tapes to fibrils, via intermediate states that include twisted ribbons. Addition of SDS is also shown to enhance the development of remarkable lateral ‘‘stripes’’ on the nanostructures, which have a 4 nm periodicity. This is ascribed to counterion condensation. The transition in the nanostructure leads to changes in macroscopic properties, in particular a transition from sol to gel is noted on increasing SDS (with a further reentrant transition to sol on further increase of SDS concentration). Formation of a gel may be useful in applications of this PA in skincare applications and we show that this can be controlled via development of a network of fine stranded fibrils

Conformation of Circular DNA in 2 Dimensions

The conformation of circular DNA molecules of various lengths adsorbed in a 2D conformation on a mica surface is studied. The results confirm the conjecture that the critical exponent $\nu$ is topologically invariant and equal to the SAW value (in the present case $\nu=3/4$), and that the topology and dimensionality of the system strongly influences the cross-over between the rigid regime and the self-avoiding regime at a scale $L\approx 8 \ell_p$. Additionally, the bond correlation function scales with the molecular length $L$ as predicted. For molecular lengths $L\leq5 \ell_p$, circular DNA behaves like a stiff molecule with approximately elliptic shape.Comment: 4 pages, 5 figure

Analytic Continuation of Mellin Transforms up to two-loop Order

The analytic continuation of the Mellin transforms to complex values of N for the basic functions $g_i(x)$ of the momentum fraction x emerging in the quantities of massless QED and QCD up to two-loop order, as the unpolarized and polarized splitting functions, coefficient functions, and hard scattering cross sections for space- and time-like momentum transfer are evaluated. These Mellin transforms provide the analytic continuations of all finite harmonic sums up to the level of the threefold sums of transcendentality four, where the basis-set ${g_i(x)}$ consists of products of {\sc Nielsen}-integrals up to transcendentality four. The computer code {\tt ANCONT} is provided.Comment: 31 pages LATEX, 1 style fil

Fractal Dimension and Localization of DNA Knots

The scaling properties of DNA knots of different complexities were studied by atomic force microscope. Following two different protocols DNA knots are adsorbed onto a mica surface in regimes of (i) strong binding, that induces a kinetic trapping of the three-dimensional (3D) configuration, and of (ii) weak binding, that permits (partial) relaxation on the surface. In (i) the gyration radius of the adsorbed DNA knot scales with the 3D Flory exponent $\nu\approx 0.58$ within error. In (ii), we find $\nu\approx 0.66$, a value between the 3D and 2D ($\nu=3/4$) exponents, indicating an incomplete 2D relaxation or a different polymer universality class. Compelling evidence is also presented for the localization of the knot crossings in 2D.Comment: 4 pages, 3 figure

Beyond Trust Species: The Conservation Potential of the National Wildlife Refuge System in the Wake of Climate Change

Over the last two decades, the U.S. Fish and Wildlife Service (“FWS”) has come to define its conservation mission in the context of species protection. The concept of “trust species” is now a common focal point for the myriad responsibilities of the FWS. This has become problematic for one of the major programs of the agency: management of the world’s largest biodiversity conservation network, the national wildlife refuge system (“NWRS”). A major legislative overhaul of the NWRS charter and the imperatives of climate change adaptation have weakened the concept as a reliable touchstone for NWRS management and expansion. The FWS should build on its culture and history to respond to new challenges that the conservation network cannot meet with the “trust species” concept alone. While management to benefit specific species offers a simple measure of accomplishment, as a policy tool it creates more problems than it solves. Adherence to the “trust species” theme limits full engagement with, and abdicates the FWS’ leadership role in, contemporary conservation challenges and science. This article makes the case for alternative measures of NWRS conservation success that move beyond just counting populations. We begin in Part I by tracing the rise of the trust concept to prominence as the dominant FWS conservation theme. We illustrate how the idea works in practice with three examples. In Part II we proceed to analyze what the “trust species” theme offers for conservation objectives and what problems it presents for the NWRS. We conclude that, on balance, its strengths do not justify its predominance. In particular, the trust concept has four problems. First, it fails to capture the full, systemic statutory mandate, and thus neglects an important part of Congress’ instructions. Second, it invites confusion with real federal trust duties pertaining to natural resources damages and relations with Indian tribes. Third, it risks conflation with state public trust doctrines, and therefore blurs the distinction between the FWS’ functions and the state role in wildlife management. Fourth, it narrows the FWS’ conservation vision to only a few elements of the broader ecological concerns animating landscape-level nature protection. Part III shows how climate change, ecosystem management, and land acquisition would be better addressed through a broader approach. We conclude with some suggestions for alternatives to the reductive “trust species” focus. Ecological integrity offers a more accurate theme for the NWRS goals, a more robust tool for adapting to climate change, and a concept that the scientific literature recognizes and quantifies

Harmonic Sums and Mellin Transforms up to two-loop Order

A systematic study is performed on the finite harmonic sums up to level four. These sums form the general basis for the Mellin transforms of all individual functions $f_i(x)$ of the momentum fraction $x$ emerging in the quantities of massless QED and QCD up to two--loop order, as the unpolarized and polarized splitting functions, coefficient functions, and hard scattering cross sections for space and time-like momentum transfer. The finite harmonic sums are calculated explicitly in the linear representation. Algebraic relations connecting these sums are derived to obtain representations based on a reduced set of basic functions. The Mellin transforms of all the corresponding Nielsen functions are calculated.Comment: 44 pages Latex, contract number adde