Analysis of the Influence of Droplet Breakup Time using Kelvin-Helmholtz Model, on the Diesel Spray Formation, Evaporation and Combustion

A numerical simulation of the intake and compression stroke and fuel spray and combustion in a direct injection compression ignition engine was performed using the Converge CFD software. For this purpose, the Reynolds Average Navier-Stokes (RANS) k-e RNG model and an n-dodecane kinetic mechanism were used in order to obtain the flow fields in the cylinder and to perform the breakup time analysis of the Kelvin-Helmholtz model in the variables related to the spray and combustion. The turbulent flow inside the cylinder was analysed, obtaining consistent results with experimental pressure data and other research authors. The droplet breakup time is evaluated as a function of the breakup time constant (B1), the initial droplet radius (ro), the wavelength and the maximum growth rate ( . The results indicate that the numerical method and the models used in this work are adequate to perform subsequent representative combustion analyses with values of B1=7. It was possible to show that the formation of the species OH is greater for low values of B1. Also, higher values of the breakup time, variables such as temperature, pressure, fuel evaporation, ignition delay, and species formation are affected.

Predicting the growth of Listeria monocytogenes in cooked sliced deli turkey breast as function of clean label antimicrobial, pH, moisture and salt

The use of antimicrobials in formulations of ready-to-eat meat and poultry products has been identified as a major strategy to control Listeria monocytogenes . The USDA-FSIS recommends no more than 2-logs of Listeria outgrowth over the stated shelf life if antimicrobials are used as a control measure for a product with post-lethality environmental exposure. This study was designed to understand the efficacy of a clean label antimicrobial against the growth of L. monocytogenes as affected by the product attributes. A response surface method-central composite design was used to investigate the effects of product pH, moisture, salt content, and a commercial “clean-label” antimicrobial on the growth of L. monocytogenes in a model turkey deli meat formulation. Thirty treatment combinations of pH (6.3, 6.5, and 6.7), moisture (72, 75, and 78%), salt (1.0, 1.5, and 2.0%), and antimicrobial (0.75, 1.375, and 2.0%) with six replicated center points and eight design star points were evaluated. Treatments were surface inoculated with a 3 log 10 CFU/g target of a five-strain L. monocytogenes cocktail, vacuum packaged, and stored at 5°C for up to 16 weeks. Populations of L. monocytogenes were enumerated from triplicate samples every week until the stationary growth phase was reached. The enumeration data was fitted to a Baranyi and Roberts growth curve to calculate the lag time and maximum growth rate for each treatment. Linear least-squares regression of the lag-time and growth-rate against the full quadratic, including the second order interaction terms, design matrix was performed. Both lag time and maximum growth rate were significantly affected ( p <0.01) by the antimicrobial concentration and product pH. Product moisture and salt content affected ( p <0.05) lag phase and maximum growth rate, respectively. The availability of a validated growth model assists meat scientists and processors with faster product development and commercialization.

Broadband Design of Acoustic Metasurfaces for the Stabilization of a Mach 4 Boundary Layer Flow

A piecewise acoustic metasurface is designed to suppress the first mode while marginally amplifying the Mack second mode in a Mach 4 flat-plate boundary layer (BL) flow. The results of linear stability theory (LST) and the eN method demonstrate the stabilization effect and transition delay performance, respectively. However, the direct numerical simulation (DNS) results indicate that the designed broadband acoustic metasurface actually weakly excites the first mode with a slightly larger fluctuating pressure amplitude at the surface, which is in contrast to the analysis of LST. The discrepancies are found to lie in the ‘roughness’ effect caused by the recirculation zones inside the microslits and the alternating expansion and compression waves induced at the slit edges, which significantly amplifies the first mode. For further clarification of the competitive mechanism between the acoustic stabilization and ‘roughness’ destabilization effects of metasurfaces on the first mode, a carefully designed metasurface is installed at the maximum growth rate region, which excites the first mode on the metasurface but inhibits its development downstream.

Ecophysiology of Fusarium chaquense a Novel Type A Trichothecene Producer Species Isolated from Natural Grasses

Fusarium chaquense, a recently formally described novel species, has been identified as an T-2 toxin (T-2), HT-2 toxin (HT-2) and other toxins producer in natural grasses (Poaceae) from Argentina. The major objective of this study was to describe the effect of water activity (aW, 0.995, 0.98, 0.95, 0.93 and 0.91), temperature (15, 25 and 30 °C) and incubation time (5, 15 and 25 days) on growth and to evaluate the production of T-2, HT-2 toxins and beauvericin (BEA) by two F. chaquense strains in a grass-based media. The results showed a wide range of conditions for F. chaquense growth and mycotoxin production. Both strains had a maximum growth rate at the highest aW (0.995) and 25 °C. Regarding mycotoxin production, more T-2 than the other analysed mycotoxins were produced by the two strains. T-2 production was favoured at 0.995 aW and 30 °C, while HT-2 production at 0.98–0.95 aW and 15 °C. The maximum levels of BEA were produced at 0.995 aW and 25–30 °C. Two-dimensional profiles of aW by temperature interactions were obtained from these data in order to identify areas where conditions indicate a significant risk of mycotoxins accumulation on grass. For its versatility on growth and mycotoxin production in a wide range of aW and temperatures, F. chaquense would have an adaptive advantage over other Fusarium species, and this would explain its high frequency of isolation in natural grasses grown up in the Chaco wetlands.

EFFECT OF SOME AGRO-INDUSTRIAL RESIDUES ON MYCELIAL GROWTH AND PRODUCTION OF LIGNOCELLULOLYTIC ENZYMES BY A FUNGUS NATIVE TO ALGERIAN FOREST

Valorization of agricultural and agro-food by-products by fermentation constitutes a very interesting biotechnological approach for the production of lignocellulolytic enzymes. This work was carried out to reveal the effect of some lignocellulosic materials on the mycelial growth and lignocellulolytic enzymes production by Bjerkandera adusta BRFM 1916. The strain showed ABTS- and guaiacol-oxidation activities. The optimal temperature for mycelial growth was 28 °C. The maximum growth rate of this fungus was achieved on wheat bran (2.08 ± 0.05 cm day-1), followed by barley bran, with a significant reduction of 6.73%. Several agricultural lignocellulosic residues were used as substrates for enzymes production. All the data indicated differential utilization of the various materials by the fungus. The selected fungus produced good CMCase (690 ± 0.066 UL-1) and β-Glu (253 UL-1) activities on wheat bran and orange peels, respectively. A high level of MnP activity (449.21 ± 3.44 UL-1) was obtained on wheat bran.

PRODUCTIVITY OF GRAIN PRODUCTION IN RUSSIA: TRENDS AND PROSPECTS

The purpose of this study is to assess and predict the factors of productivity of Russian grain production in the context of the ongoing territorial and sectoral structural changes. The research methodology includes a retrospective assessment of the production of major grain crops in the key grain-producing zones of the country. The identification of tendencies and trends was carried out using the methods of nonlinear dynamics. The time period of the study covers 1990-2020. Calculations show that, in Russia as a whole, by 2030 there will be a stable growth in the values of the yields of grain and leguminous crops. The maximum growth rate will be demonstrated by rye (1.9 times more than the average), buckwheat (1.5) and corn (1.3). Wheat and barley yields will grow at the average level. A significant part of the structure of grain production with growth trends will be wheat (winter and spring), as well as barley and corn for grain. The following federal districts will be the leading regions of Russia in grain production: Southern, Central, Povolzhsky, Siberian, North Caucasian. Russia has a enough margin of stability in the productivity of grain production. The growth trends of the main indicators of the productivity of grain production in Russia will continue: the gross harvest of grain and leguminous crops due to the factors of intensification of production has a reserve of 10.4 - 25.7 million tons in excess of the officially planned indicators by 2030. The extensive option of grain production (expansion of the sown area while maintaining the global growth rates of yield) is additionally estimated at 24.5 - 42.6 million tons of the planned values of strategic documents. An increase in demand for grain in the world market will lead to the strengthening of wheat in the structure of grain production in Russia, a sharp increase in specialized zones for the production of corn for grain

Subtle Differences in the Representation of Consumer Dynamics Have Large Effects in Marine Food Web Models

Projecting ocean biogeochemistry and fisheries resources under climate change requires confidence in simulation models. Core to such models is the description of consumer dynamics relating prey abundance to capture, digestion efficiency and growth rate. Capture is most commonly described as a linear function of prey encounter or by rectangular hyperbola. Most models also describe consumers as eating machines which “live-to-eat,” where growth (μ) is limited by a maximum grazing rate (Gmax). Real consumers can feed much faster than needed to support their maximum growth rate (μmax); with feeding modulated by satiation, they “eat-to-live.” A set of strategic analyses were conducted of these alternative philosophies of prey consumption dynamics and testing of their effects in the StrathE2E end-to-end marine food web and fisheries model. In an experiment where assimilation efficiencies were decreased by 10%, such as might result from a change in temperature or ocean acidity, the different formulation resulted in up to 100% variation in the change in abundances of food web components, especially in the mid-trophic levels. Our analysis points to a need for re-evaluation of some long-accepted principles in consumer-resource modeling.

Bank Ownership vs Credit Growth: Empirical Evidence from Vietnamese Commercial Banks

This paper is aimed at analyzing the relationship between bank ownership and credit growth of Vietnamese commercial banks. With the data of 20 commercial banks in period 2009-2018 period, the REM method is applied. The key findings are: First, credit growth rate of state-owned commercial banks in Vietnam is higher than of private commercial banks, which is opposite to the expected signal. The main reasons are (i) decision making of state-owned commercial banks on lending are backed by the government, which is more straight-forward than private banks; (ii) State Bank of Vietnam considers credit policy as one of the important monetary policy tools, of which state-owned commercial banks are the key drivers; (iii) state-owned commercial banks have stable and cheap funding sources, which create the good base for expanding credit with cheap interest rates. Second, asset size does not have any impact on credit growth. Credit growth rates are determined by the bank’s overall performance and maximum growth rate set by State Bank of Vietnam, not on assets. Third, the other bank-specific factors are statistically significant with credit growth, of which liquidity and ROA have the strongest influences. Recommendations for better credit growth management of commercial banks include: (i) State Bank of Vietnam and the Government to ensure soundness of the banking system, including applying the Basel II requirements to all banks; and establish more support packages in order to boost the lending activities of privately-owned banks. (ii) Commercial banks to reduce its non-performing loans in order to stimulate the growth in lending. Keywords: bank liquidity, bank ownership, credit growth, non-performing loans, ROA.

Comparison of Intra-Annual Xylem and Phloem Formation of Picea crassifolia Stands at Two Latitudes in Northwest China

Understanding the changes in xylem and phloem formation of trees and their relationship along latitudes are important for evaluating and predicting how fragile forests may respond to climate change; however, corresponding studies are still relatively scarce. This study investigated the intra-annual dynamics of xylem and phloem formation of Picea crassifolia and their relationship at two latitudes of arid and semi-arid forests in China. The results showed that both xylem and phloem formation varied at different latitudes. Xylem formation at the low-latitude site (Luoshan) started two weeks earlier than that at the high-latitude site (Helanshan) but ended one week later, resulting in an extended growing season at the low-latitude site. Phloem formation preceded cambium activity and xylogenesis at both sites by 24.6 days in Luoshan, which had warmer conditions, and by 17.3 days in Helanshan. In Luoshan, compared to Helanshan, there occurred significantly more enlarging and wall thickening cells, during (relatively wet) June–August, but significantly fewer enlarging and wall thickening cells as well as total xylem cells, during (relatively dry) April–May. Sample trees produced significantly fewer early phloem cells during the early growing season (April–May) in Luoshan, but generated significantly more late phloem cells during the late growing season in Helanshan. Additionally, different trade-offs between xylem and phloem formation were observed at different sites. The longer duration of early phloem formation might have shortened the duration of xylem lignification in Helanshan; in Luoshan, the date that late phloem reached its maximum growth rate was significantly positively correlated with the date when xylem lignification ended. The results revealed the plasticity of xylem and phloem formation under changing environmental conditions and a complex and site-specific relationship between xylem and phloem formation. These findings could help us better understand and predict the future growth of arid and semi-arid forests in China in response to climate change.

Estimating the maximal growth rates of eukaryotic microbes from cultures and metagenomes via codon usage patterns

Microbial eukaryotes are ubiquitous in the environment and play important roles in key ecosystem processes, including accounting for a significant portion of global primary production. Yet, our tools for assessing the functional capabilities of eukaryotic microbes in the environment are quite limited because many microbes have yet to be grown in culture. Maximum growth rate is a fundamental parameter of microbial lifestyle that reveals important information about an organism's functional role in a community. We developed and validated a genomic estimator of maximum growth rate for eukaryotic microbes, enabling the assessment of growth potential for both cultivated and yet-to-be-cultivated organisms. We produced a database of over 700 growth predictions from genomes, transcriptomes, and metagenome-assembled genomes, and found that closely related and/or functionally similar organisms tended to have similar maximal growth rates. By comparing the maximal growth rates of existing culture collections with environmentally-derived genomes we found that, unlike for prokaryotes, culture collections of microbial eukaryotes are only minimally biased in terms of growth potential. We then extended our tool to make community-wide estimates of growth potential from over 500 marine metagenomes, mapping growth potential across the global oceans. We found that prokaryotic and eukaryotic communities have highly correlated growth potentials near the ocean surface, but that this relationship disappears deeper in the water column. This suggests that fast growing eukaryotes and prokaryotes thrive under similar conditions at the ocean surface, but that there is a decoupling of these communities as resources become scarce deeper in the water column.