Uniaxial-deformation behavior of ice Ih as described by the TIP4P/Ice and mW water models

Using molecular dynamics simulations, we assess the uniaxial deformation response of ice Ih as described by two popular water models, namely, the all-atom TIP4P/Ice potential and the coarse-grained mW model. In particular, we investigate the response to both tensile and compressive uniaxial deformations along the [0001] and [01̄10] crystallographic directions for a series of different temperatures. We classify the respective failure mechanisms and assess their sensitivity to strain rate and cell size. While the TIP4P/Ice model fails by either brittle cleavage under tension at low temperatures or large-scale amorphization/melting, the mW potential behaves in a much more ductile manner, displaying numerous cases in which stress relief involves the nucleation and subsequent activity of lattice dislocations. Indeed, the fact that mW behaves in such a malleable manner even at strain rates that are substantially higher than those applied in typical experiments indicates that the mW description of ice Ih is excessively ductile. One possible contribution to this enhanced malleability is the absence of explicit protons in the mW model, disregarding the fundamental asymmetry of the hydrogen bond that plays an important role in the nucleation and motion of lattice dislocations in ice Ih.Fil: Santos Flórez, Pedro Antonio. Universidade Estadual de Campinas; BrasilFil: Ruestes, Carlos Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: de Koning, Maurice. Universidade Estadual de Campinas; Brasi

"The Keynesian Roots of Stock-flow Consistent Macroeconomic Models: Peering Over the Edge of the Short Period"

This paper argues that institutionally rich stock-flow consistent models—that is, models in which economic agents are identified with the main social categories/institutional sectors of actual capitalist economies, the short period behavior of these agents is thoroughly described, and the "period by period" balance sheet dynamics implied by the latter is consistently modeled—are (1) perfectly compatible with John Maynard Keynes's theoretical views, (2) the ideal tool for rigorous post-Keynesian analyses of the medium run, and (3) therefore crucial to the consolidation of the broad post-Keynesian research program.

"Revisiting (and Connecting) Marglin-Bhaduri and Minsky--An SFC Look at Financialization and Profit-led Growth"

Many heterodox strands of thought share both a concern with the study of different phases or growth regimes in the history of capitalism and the use of formal short-run models as an analytical tool. This text suggests that (1) this strategy is potentially misleading; (2) that the stock-flow consistent (SFC) approach, while providing a general framework that may facilitate the dialogue among those currents, is particularly well suited to all those who think that macroeconomic models may illuminate historical quests; and (3) that the main intuitions may be conveyed through the "benchmark" Post Keynesian SFC model presented by Dos Santos and Zezza (2008), dispensing with the complex computer simulations that are normally employed by SFC authors.

Enzymatic Inhibition By Lignin During Second Generation Ethanol Production

An important hindrance to commercialization of lignocellulosic ethanol is the high cost of enzymes. Reducing enzyme loadings is necessary to reduce costs. Knowledge of the inhibitors of these enzymes is necessary to better inform enzyme development and process design. Five factors have been identified: soluble inhibitors, solid lignin adsorption, product inhibition, mixing efficiency and oxygen deactivation of the enzymes that hydrolyze cellulose to glucose. These factors are intertwined and properly assessing them individually require the elimination of the others. Isolating each factor, however, has not been done throughout literature leading to lumped constants. Soluble inhibitors reduce conversion sharply leading to high enzyme loadings and impeding the evaluation of any of the other factors. Through washing, the soluble inhibitors may be eliminated, and only washed biomass (either sugar cane bagasse or corn stover) was used to study the other factors. This work further investigates adsorption on lignin, mixing, and the effect of air on washed pretreated sugarcane bagasse and corn stover. Studies of enzyme adsorption on lignin, showed lignin/enzyme interaction was temperature dependent and proportional to pretreatment severity. Lowering reaction temperatures to 30°C, eliminated enzyme adsorption and was opposite to what was expected, indicating a possible entropic process. On a practical basis, the additional free enzyme partial makes up for the lower activity of the enzyme mixture that occurs due to reduced reaction rate at the lower temperature of 30°C. Lower hydrolysis rates also require longer reaction times to achieve the same extent of conversion to glucose. An alternative to counter adsorption of enzyme on lignin occurs by regulating the amount of lignin exposed by adjusting pretreatment conditions. At higher temperatures a large portion of lignin is solubilized and redeposited, increasing lignin exposure and adsorption is higher. At a lower severity, lignin is less exposed, and adsorption is lower. However, higher severity is needed to increase the accessibility of cellulose, thereby facilitating accessibility and conversion. For sugarcane bagasse a 10.74 severity pretreatment (200°C for 20 minute) using liquid hot water resulted in minimal protein adsorption and therefore was interpreted to coincide with a small extent of lignin exposure, as qualitatively confirmed using SEM. Efficient conversion (71- 76%) was achieved when hydrolysis with 6.5 mg of Cellic CTEC3 / g total solids. A more recalcitrant biomass would require a more intense pretreatment to be hydrolyzed at satisfactory levels. Mixing and product inhibition were more intricately linked than the others. When efficient mixing was achieved, product inhibition was decreased relative to cases where mixing was not readily achieved. In these runs, concentrations of pretreated and washed corn stover were at initial concentrations of 10 to 200 g/L. At 200 g/L, the higher efficiency led to faster liquefaction of biomass in the early stages. Faster liquefaction resulted in significantly high glucose conversions (up to 47% final yields) after 72 hours of hydrolysis compared to minimally liquefied material where conversion was 34% Efficient mixing allowed deactivation due to air to be evaluated properly. This factor is the least understood in the literature and has a potentially major effect on the amount enzyme required for a given level of hydrolysis. Deactivation was isolated and observed by measuring conversion in a mixed 1 L reactor either in the presence of absence of air, except in these experiments with a different enzyme formulation, Cellic CTEC2 was used at 3.6 mg protein (Cellic CTEC2) / g solids. Cellic CTEC2 has lower activity, and the lower amount ensured that differences between the two conditions would be more obvious. Air was shown to decrease conversion by 10 to 15% with lower loss of activity corresponding to high solids loading. The impact of unfavorable conditions (presence of lignin, inefficient mixing and inadequate air exposure) can be minimized by adjusting the biomass pretreatment and hydrolysis processes. The extent of adsorption of cellulolytic enzymes on lignin can be reduced by lowering hydrolysis temperature or reducing pretreatment severity. Efficient mixing facilitates liquefaction and increases final glucose conversion from cellulose compared to inefficient mixing methods. Limiting the presence of air increases enzyme activity and the associated final conversions. Adoption of the combined adjustments reduced enzyme loading by 50% (from 6 FPU to 3 FPU / g solids) for the enzyme Cellic CTEC2

Sugarcane bagasse hydrolysis enhancement using BSA

Lignocellulose is composed of polysaccharides linked to lignin and other aromatic compounds, making the sugars not readily available to fermentation. This entails that biomass must go through the unit operations of pretreatment and enzyme hydrolysis. Pretreatment opens the structure to allow the enzymes to act on and hydrolyze cellulose and hemicellulose to glucose and/or xylose which in turn are fermented to ethanol. Concomitantly, the enzymes interact with soluble phenols and insoluble solids derived from lignin that inhibit hydrolysis. This leads to high enzyme loadings and higher production costs. Soluble phenols can be eliminated through washing. Insoluble lignin, however, demands another approach. Using bovine serum albumin (BSA) and pretreated sugarcane bagasse, the effect of blocking solid lignin from adsorbing enzymes during hydrolysis after 72 hours was evaluated. Hydrolysis was carried using 6.25 FPU (Cellulase 13P) and 12.5 IU (Novozyme 188) /g solids (10 mg protein/g solids) at pH 4.8 and 50°C. The conversion was generally higher when BSA was present, 51% (±1%) vs 42% (±1%) with 1.5% solids loading and 46% (±1%) vs 40% (±1%) with 8% solids loading. The use of BSA produced an increase in the final conversion (p-value \u3c 0.001), but conversion decreased as loadings increased. This has been observed in multiple other studies and cannot be explained by a single factor. The basis of this phenomenon is being investigated. Initial experiments that adjusted the enzyme preparation to 2.5 FPU/g glucan (10.5 mg protein/g glucan) of Cellic CTEC3 and improved the mixing of the slurry elevated the conversion to 72% (±5%) without BSA and 76% (±10%) with it, at 1% (w/v) solids loading and 73% (±6%) without BSA and 80% (±10%) with it, at 10% (w/v) solids loading

Herdabilidade estimada por diferentes métodos em quatro gerações de progênies de um cruzamento de guandu

The objective of this work was to compare different methods to estimate heritability in 30 pigeon pea families from the F3, F4, F5, and F6 generations, for nine variables. The experimental design was a randomized complete block with three replicates and 20 plants per plot. Broad-sense heritability was estimated by the analysis of variance (ANOVA) [h2b-E(MS)], restricted maximum likelihood/best linear unbiased prediction (REML/BLUP) (h2b-REML), parent-offspring regression (h2PO), and standard deviation unit (h2UP). The h2b-E(MS) and h2b-REML estimates were similar for seven of the analyzed variables. For a higher genetic control and easier selection, values of h2b-E(MS) and h2b-REML >0.70 were estimated for two variables in four generations, two variables in three generations, three variables in two generations, and one variable in one generation. Values of h2UP and h2PO >0.70 were obtained for four and five variables, respectively. The estimates via regression or parent-offspring correlation showed some values outside the expected range of 0 to 1. The ANOVA [h2b-E(MS)] and REML/BLUP [h2b-REML] methods are the best to estimate pigeon pea heritability.O objetivo deste trabalho foi comparar diferentes métodos para estimar a herdabilidade em 30 linhagens de guandu das gerações F3, F4, F5 e F6,  para nove variáveis. O delineamento experimental foi em blocos ao acaso, com três repetições e 20 plantas por parcela. Estimou-se a herdabilidade no sentido amplo por meio de análise de variância (ANOVA) [h2b-E(MS)], máxima verossimilhança restrita/melhor predição linear não viciada (REML/BLUP) (h2b-REML), regressão pai-filho (h2PO) e unidade do desvio-padrão (h2UP). As estimativas de h2b-E(MS) e h2b-REML foram de magnitude próxima para sete das variáveis analisadas. Para maior controle genético e facilidade na seleção, valores de h2b-E(MS) e h2b-REML >0,70 foram estimados para duas variáveis em quatro gerações, duas variáveis em três gerações, três variáveis em duas gerações e uma variável em uma geração. Valores de h2UP e h2PO >0,70 foram obtidos para quatro e cinco variáveis, respectivamente. As estimativas via regressão ou correlação pai-filho mostraram alguns valores fora da variação esperada de 0 a 1. Os métodos ANOVA [h2b-E(MS)] e REML/BLUP [h2b-REML] são os melhores para estimar a herdabilidade em guandu

GESTÃO DO PROCESSO DE CAPTAÇÃO DE LEITE: UM ESTUDO DE CASO NA COOPERATIVA AGRÃCOLA ALTO RIO GRANDE LTDA (CAARG)

The aim of this work was to assess the milking process in an agricultural cooperative in Lavras, Minas Gerais state. The study was done between August and November/2004, employing a qualitative research methodology that involved the researchers and the cooperative’s employees. Process management promotes the organization and management of information in the company, favoring cost administration and control. The study presented some lines with average costs above R$ 1.51/Km, and others below. This fact could impair the efficiency of the process. To ensure quality, legal parameters were defined, through laboratory analysis, to classify the milk. The observance of the strong and weak points are the best way to maximize the organization’s efficiency. However, these weak points deserve special attention from the CAARG’s decision makers in order to guarantee the cooperative’s performance. The main strategies implemented were financing and allowance of the outgoing tanks, combined with payment according to the volume and quality of the milk. Nevertheless, vertical integration should be adopted through supply contracts or quota definition, which is extremely important in guaranteeing not only the supply, but mainly the quality of the raw-material.competitive Strategy, Agricultural Cooperative, Vertical Integration, and costs of milk transportation, Agribusiness, Agricultural Finance, Industrial Organization,