Effect of cooling and coating on thermoplastic starch/poly(lactic acid) blend sheets

AbstractThe influence of the processing conditions (cooling rate) and coating on the physicochemical properties of thermoplastic starch/poly(lactic acid) blend sheets was studied. Two cooling rates were used: fast and slow, and in the latter case the sheets were both non-coated and coated with cross-linked chitosan. The physicochemical properties investigated were crystallinity, morphology, water affinity (moisture sorption isotherm, water vapor permeability, water solubility and contact angle) and mechanical properties. In general, the sheets cooled at the slow rate were more crystalline, less permeable and less soluble in water than those cooled at the fast rate. They also produced a more homogeneous morphology. The coated sheets were less soluble in water and mechanically stronger than uncoated sheets cooled at the slow rate. The concentration of plasticizer in the TPS affected only the sorption isotherm and contact angle since a higher plasticizer content caused a greater affinity for water

Particle tracking in kaon electroproduction with cathode-charge sampling in multi-wire proportional chambers

Wire chambers are routinely operated as tracking detectors in magnetic spectrometers at high-intensity continuous electron beams. Especially in experiments studying reactions with small cross-sections the reaction yield is limited by the background rate in the chambers. One way to determine the track of a charged particle through a multi-wire proportional chamber (MWPC) is the measurement of the charge distribution induced on its cathodes. In practical applications of this read-out method, the algorithm to relate the measured charge distribution to the avalanche position is an important factor for the achievable position resolution and for the track reconstruction efficiency. An algorithm was developed for operating two large-sized MWPCs in a strong background environment with multiple-particle tracks. Resulting efficiencies were determined as a function of the electron beam current and on the signal amplitudes. Because of the different energy-losses of pions, kaons, and protons in the momentum range of the spectrometer the efficiencies depend also on the particle species

Coherent \pi^0 threshold production from the deuteron at Q^2 = 0.1 GeV^2/c^2

First data on coherent threshold \pi^0 electroproduction from the deuteron taken by the A1 Collaboration at the Mainz Microtron MAMI are presented. At a four-momentum transfer of q^2=-0.1 GeV^2/c^2 the full solid angle was covered up to a center-of-mass energy of 4 MeV above threshold. By means of a Rosenbluth separation the longitudinal threshold s wave multipole and an upper limit for the transverse threshold s wave multipole could be extracted and compared to predictions of Heavy Baryon Chiral Perturbation Theory.Comment: 7 pages, 7 figures, latex2

Precise Neutron Magnetic Form Factors

Precise data on the neutron magnetic form factor G_{mn} have been obtained with measurements of the ratio of cross sections of D(e,e'n) and D(e,e'p) up to momentum transfers of Q^2 = 0.9 (GeV/c)^2. Data with typical uncertainties of 1.5% are presented. These data allow for the first time to extract a precise value of the magnetic radius of the neutron.Comment: 10 pages, 2 figures, submitted to Physics Letters

Mapping soil organic carbon content in Patagonian forests based on climate, topography and vegetation metrics from satellite imagery

Soil organic carbon (SOC) content supports several ecosystem services. Quantifying SOC requires: (i) accurate C estimates of forest components, and (ii) soil estimates. However, SOC is difficult to measure, so predictive models are needed. Our objective was to model SOC stocks within 30 cm depth in Patagonian forests based on climatic, topographic and vegetation productivity measures from satellite images, including Dynamic Habitat Indices and Land Surface Temperature derived from Landsat-8. We used data from 1320 stands of different forest types in Patagonia, and random forest regression to map SOC. The model captured SOC variability well (R2 = 0.60, RMSE = 22.1%), considering the huge latitudinal extension (36.4◦ to 55.1◦ SL) and the great diversity of forest types. Mean SOC was 134.4 ton C ha−1 ± 25.2, totaling 404.2 million ton C across Patagonia. Overall, SOC values were highest in valleys of the Andes mountains and in southern Tierra del Fuego, ranging from 53.5 to 277.8 ton C ha−1 for the whole Patagonia region. Soil organic carbon is a metric relevant to many applications, connecting major issues such as forest management, conservation, and livestock production, and having spatially explicit estimates of SOC enables managers to fulfil the international agreements that Argentina has joined.EEA EsquelFil: Martínez Pastur, Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas (CADIC). Laboratorio de Recursos Agroforestales; ArgentinaFil: Aravena Acuña, Marie Claire. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas (CADIC). Laboratorio de Recursos Agroforestales; ArgentinaFil: Silveira, Eduarda M. O. University of Wisconsin. Department of Forest and Wildlife Ecology. SILVIS Lab.; Estados UnidosFil: von Müller, Axel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agroforestal Esquel; ArgentinaFil: La Manna, Ludmila. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: La Manna, Ludmila. Universidad Nacional de la Patagonia San Juan Bosco. Facultad de Ingeniería. Centro de Estudios Ambientales Integrados; ArgentinaFil: González Polo, Marina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: González Polo, Marina. Universidad Nacional del Comahue. Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA); ArgentinaFil: Chaves, Jimena E. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas (CADIC). Laboratorio de Recursos Agroforestales; ArgentinaFil: Cellini, Juan M. Universidad Nacional de La Plata. Laboratorio de Investigaciones en Maderas (LIMAD); ArgentinaFil: Lencinas, María V. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas (CADIC). Laboratorio de Recursos Agroforestales; ArgentinaFil: Radeloff, Volker C. University of Wisconsin. Department of Forest and Wildlife Ecology. SILVIS Lab.; Estados UnidosFil: Pidgeon, Anna M. University of Wisconsin. Department of Forest and Wildlife Ecology. SILVIS Lab.; Estados UnidosFil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral; Argentina.Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Cosmological particle production, causal thermodynamics, and inflationary expansion

Combining the equivalence between cosmological particle creation and an effective viscous fluid pressure with the fact that the latter represents a dynamical degree of freedom within the second-order Israel-Stewart theory for imperfect fluids, we reconsider the possibility of accelerated expansion in fluid cosmology. We find an inherent self-limitation for the magnitude of an effective bulk pressure which is due to adiabatic (isentropic) particle production. For a production rate which depends quadratically on the Hubble rate we confirm the existence of solutions which describe a smooth transition from inflationary to noninflationary behavior and discuss their interpretation within the model of a decaying vacuum energy density. An alternative formulation of the effective imperfect fluid dynamics in terms of a minimally coupled scalar field is given. The corresponding potential is discussed and an entropy equivalent for the scalar field is found.Comment: 16 pages, revtex file, submitted to Phys. Rev.

Nonequilibrium phase transitions induced by multiplicative noise: effects of self-correlation

A recently introduced lattice model, describing an extended system which exhibits a reentrant (symmetry-breaking, second-order) noise-induced nonequilibrium phase transition, is studied under the assumption that the multiplicative noise leading to the transition is colored. Within an effective Markovian approximation and a mean-field scheme it is found that when the self-correlation time of the noise is different from zero, the transition is also reentrant with respect to the spatial coupling D. In other words, at variance with what one expects for equilibrium phase transitions, a large enough value of D favors disorder. Moreover, except for a small region in the parameter subspace determined by the noise intensity and D, an increase in the self-correlation time usually preventsthe formation of an ordered state. These effects are supported by numerical simulations.Comment: 15 pages. 9 figures. To appear in Phys.Rev.

Self energies of the pion and the delta isobar from the ^3He(e,e'pi^+)^3H reaction

In a kinematically complete experiment at the Mainz microtron MAMI, pion angular distributions of the $^3$He(e,e'$\pi^+)^3$H reaction have been measured in the excitation region of the $\Delta$ resonance to determine the longitudinal ($L$), transverse ($T$), and the $LT$ interference part of the differential cross section. The data are described only after introducing self-energy modifications of the pion and $\Delta$-isobar propagators. Using Chiral Perturbation Theory (ChPT) to extrapolate the pion self energy as inferred from the measurement on the mass shell, we deduce a reduction of the $\pi^+$ mass of $\Delta m_{\pi^+} = (-1.7^{+ 1.7}_{- 2.1})$ MeV/c$^2$ in the neutron-rich nuclear medium at a density of $\rho = (0.057^{+ 0.085}_{- 0.057})$ fm$^{-3}$. Our data are consistent with the $\Delta$ self energy determined from measurements of $\pi^0$ photoproduction from $^4$He and heavier nuclei.Comment: Elsart, 12 pages and 4 figures, Correspondent: Professor Dr. Dr. h.c. mult. Achim Richter, [email protected], submitted to Phys. Rev. Let