Detailed analysis of combustion stability in a spark-assisted compression ignition engine under nearly stoichiometric and heavy EGR conditions

Extending the load range of low-temperature combustion is of priority to meet future CO2 and emission targets for reciprocating engine applications. Spark assist is a feasible solution to this challenge for mono-fuel homogeneous charge compression ignition (HCCI). This paper explains how spark-assisted compression ignition (SACI) enables ultra-low NOX targets to be met, with acceptable pressure rise rates and combustion stability, at high load boundary conditions, favourable for HCCI/SACI transition. The work provides new methods of combustion analysis which give better understanding of the mechanisms and their implementation for real-time control of SACI engines. The goals are achieved by a combination of single-cylinder engine research and high-fidelity/high-speed, model-based calculations, performed on an individual cycle basis. The results show that determining the start of the kinetic phase in SACI is possible via standard combustion indicators. The new method is two orders of magnitude faster than the commonly used spline-Wiebe approach. With real-time capability and proven correlation to temperature evolution, triggered by propagating flame, the method enables in-cycle predictive control. Additionally, it gives a deeper insight of the mechanisms underpinning the demonstrated superior performance. The study shows the capability to run SACI at indicated mean effective pressure (IMEP) of 0.5 MPa with engine-out NOX below Euro VI´s heavy-duty engine limit and with specific fuel consumption of 207 g/kWh. Importantly, pressure rise rate and variation in IMEP do not exceed 0.25 MPa/CAD and 3% respectively. Margins for critical parameters are far greater than for baseline autonomous HCCI, providing significant load extension potential.©2020 Elsevier. This manuscript version is made available under the Creative Commons Attribution–NonCommercial–NoDerivatives 4.0 International (CC BY–NC–ND 4.0) license, https://creativecommons.org/licenses/by-nc-nd/4.0/fi=vertaisarvioitu|en=peerReviewed

Effect of physicochemical parameters on zooplankton in the brackish, coastal Vistula Lagoon

This paper analyzes whether physicochemical properties significantly influence the occurrence of zooplankton in a brackish reservoir. The studies were carried out on the Vistula Lagoon in August and September from 2006 to 2009 at 32 research sites. The environmental conditions in the Vistula Lagoon varied widely. At the time of the investigation, 17 species of rotifers, six species of Cladocera, and ten species of Copepoda were noted, and the total density of plankton fauna ranged from 145 to 765 ind. dm−3. Statistical analysis demonstrated a significant correlation between the occurrence of some zooplankton species and certain environmental parameters, whereas the sampling sites were grouped according to study years. The zooplankton systems recorded at the research sites in 2006 constitute the most disparate group. Thus, it can be concluded that physicochemical properties might significantly impact both individual species (depending on their environmental demands) and entire zooplankton clusters

Zooplankton diversity of drainage system reservoirs at an opencast mine

The aim of this study was to determine the structure of zooplankton in three artificial water reservoirs, the technological function of which is to pre-treat waters from a drainage system of a brown coal open mine by removing inorganic suspension. The background for the zooplankton qualitative and quantitative analyses was the hydrochemical conditions in the individual reservoirs. The greatest zooplankton abundance (N), number of taxa (n), Shannon’s diversity (H'), and species eveness (J') was noted in reservoir Chabielice (Nmean = 1311 ind. L−1, n = 26, H' = 2.09, J' = 0.64) which was dominated by eurytopic Rotifera species (Keratella cochlearis,Keratella tecta,Keratella valga,Polyarthra longiremis,Filinia longiseta). Their abundance was positively correlated with water pH and nutrient concentrations. Reservoir Kamień was characterized by the highest mean values of total suspension (9.6 mg L−1), chlorophyll a (Chl a) content (10.4 μg L−1), and water temperature (20.0 °C). These factors significantly correlated with crustacean biomass. The thermal-oxygenation conditions, low trophic level, and low productivity of the water (Chl a = 5.4 μg L−1) in reservoir Północny determined the overall low zooplankton abundance (Nmean = 153 ind. L−1). Artificial water bodies of opencast mine drainage systems are biologically unstable, but they do have some characteristics of natural ecosystems, and they do take over their functions. Zooplankton is an indicator of their ecological functionality. Knowledge gained about such reservoirs could contribute to decision-making about strategies for water reclamation and how to manage it

Antitumor activity of antimicrobial peptides against U937 histiocytic cell line

We investigated cytotoxic activity of antimicrobial peptides of different origin (both naturally occurring and synthetic), structure and known mechanisms of action against human histiocytic lymphoma cell line U937. The strongest cytotoxic activity against U937 cell line was shown by Pexiganan MSI-78, followed by Citropin 1.1, Protegrin 1 and a synthetic lipopeptide, N-α-palmitoyl-l-lysyl-l-lysine amide (Pal-Lys-Lys-NH2). The cytotoxic activity of the peptides was more dependent on the time of incubation than concentration. Only for the lipopeptide, whose mode of action was restricted to disruption of electric potential of the cell membrane, the correlation between cytotoxicity and concentration was almost linear. The high cytotoxicity of Pexiganan MSI-78, Protegrin 1 and the lipopeptide could be basically explained by their membranolytic activity leading to necrosis. However, in the case of Citropin 1.1, the cell membrane integrity was disrupted only slightly and independently of the peptide concentration. Therefore, some other mechanism of action might be responsible for its strong dose-dependent cytotoxic activity, e.g., membranolytic activity leading to apoptosis. Furthermore, TNF-α production due to LPS (lipopolysaccharide) stimulation was suppressed by the presence of Citropin 1.1, Pexiganan MSI-78 or Protegrin 1, but not by Buforin 2 or the lipopeptide. Our experiments have shown that cytotoxic activity is not limited to some specific molecular structure of a peptide, but rather to the length of the peptide chain as it is likely to affect the efficiency of the tumor cell membrane disruption and interaction with LPS

Correlation between catchment land use/cover and macrophyte assessment of lake ecological status

The Water Framework Directive (WFD) provides the basis for developing a system to protect and restore the aquatic environment. Macrophytes are one of the groups of organisms for determining ecological status of lakes. Using partial least squares regression (PLS-R), we showed relationships between conductivity and chlorophyll a (to a lesser extent nutrient concentrations) and Ecological State Macrophyte Index (ESMI) values. However, catchment land use/cover (LU/LC) appears to be the important factor affecting macrophyte diversity as expressed by ESMI. The presence of significant correlations was found for the catchment area determined from surface runoff using the platform SCALGO Live, based on a permanently updated numerical terrain model and an accurate land use/cover database used in Poland BDOT10k. The Corine Land Cover (CLC) database commonly used in the EU appeared to be of insufficient resolution. We have shown a high positive impact of the presence of wetlands and reservoirs in the catchment on ESMI values and negative for agricultural and urbanized areas. Obtaining information on lake catchment land use and land cover is costless. Relating LU/LC to lake macrophyte assessment methods allows this no-cost method to be included in the set of biological methods for assessing lake condition. Understanding the factors that determine the condition of lakes is fundamental to managing them according to the requirements of the WFD. The results of our study indicate that the integration of lake catchment area planning with lake water management is imperative

Specific Activation of A3, A2A and A1 Adenosine Receptors in CD73-Knockout Mice Affects B16F10 Melanoma Growth, Neovascularization, Angiogenesis and Macrophage Infiltration.

CD73 (ecto-5'-nucleotidase), a cell surface enzyme hydrolyzing AMP to adenosine, was lately demonstrated to play a direct role in tumor progression including regulation of tumor vascularization. It was also shown to stimulate tumor macrophage infiltration. Interstitial adenosine, accumulating in solid tumors due to CD73 enzymatic activity, is recognized as a main mediator regulating the production of pro- and anti-angiogenic factors, but the engagement of specific adenosine receptors in tumor progression in vivo is still poorly researched. We have analyzed the role of high affinity adenosine receptors A1, A2A, and A3 in B16F10 melanoma progression using specific agonists (CCPA, CGS-21680 and IB-MECA, respectively). We limited endogenous extracellular adenosine background using CD73 knockout mice treated with CD73 chemical inhibitor, AOPCP (adenosine α,β-methylene 5'-diphosphate). Activation of any adenosine receptor significantly inhibited B16F10 melanoma growth but only at its early stage. At 14th day of growth, the decrease in tumor neovascularization and MAPK pathway activation induced by CD73 depletion was reversed by all agonists. Activation of A1AR primarily increased angiogenic activation measured by expression of VEGF-R2 on tumor blood vessels. However, mainly A3AR activation increased both the microvessel density and expression of pro-angiogenic factors. All agonists induced significant increase in macrophage tumor infiltration, with IB-MECA being most effective. This effect was accompanied by substantial changes in cytokines regulating macrophage polarization between pro-inflammatory and pro-angiogenic phenotype. Our results demonstrate an evidence that each of the analyzed receptors has a specific role in the stimulation of tumor angiogenesis and confirm significantly more multifaceted role of adenosine in its regulation than was already observed. They also reveal previously unexplored consequences to extracellular adenosine signaling depletion in recently proposed anti-CD73 cancer therapy

A₃, A_2A or A₁ adenosine receptors regulate expression of the main pro-angiogenic factors in B16F10 melanoma.

<p>Protein expression was analyzed in lysates from tumors on the 14^th day of growth in WT or CD73^-/- mice. CD73^-/- mice were treated with AOPCP and, where indicated, with specific adenosine receptor agonist, IB-MECA (agonist for A₃AR), CGS-2168 (A_2AAR) or CCPA (A₁AR). For separate control of agonist solvent, WT mice were treated with DMSO. Semi-quantitative antibody microarrays were used to obtain protein expression profile presented as the fold change between groups calculated from the mean values for each protein separately, assuming that the average expression of the protein in all three control groups is equal to 1. *P<0.05 vs. WT, ^#P<0.05 vs. WT + DMSO, ^$P<0.05 vs. CD73^-/- + AOPCP (other statistical differences are not shown).</p

Specific Activation of A₃, A_2A and A₁ Adenosine Receptors in CD73-Knockout Mice Affects B16F10 Melanoma Growth, Neovascularization, Angiogenesis and Macrophage Infiltration

<div><p>CD73 (ecto-5'-nucleotidase), a cell surface enzyme hydrolyzing AMP to adenosine, was lately demonstrated to play a direct role in tumor progression including regulation of tumor vascularization. It was also shown to stimulate tumor macrophage infiltration. Interstitial adenosine, accumulating in solid tumors due to CD73 enzymatic activity, is recognized as a main mediator regulating the production of pro- and anti-angiogenic factors, but the engagement of specific adenosine receptors in tumor progression <i>in vivo</i> is still poorly researched. We have analyzed the role of high affinity adenosine receptors A₁, A_2A, and A₃ in B16F10 melanoma progression using specific agonists (CCPA, CGS-21680 and IB-MECA, respectively). We limited endogenous extracellular adenosine background using CD73 knockout mice treated with CD73 chemical inhibitor, AOPCP (adenosine α,β-methylene 5’-diphosphate). Activation of any adenosine receptor significantly inhibited B16F10 melanoma growth but only at its early stage. At 14th day of growth, the decrease in tumor neovascularization and MAPK pathway activation induced by CD73 depletion was reversed by all agonists. Activation of A₁AR primarily increased angiogenic activation measured by expression of VEGF-R2 on tumor blood vessels. However, mainly A₃AR activation increased both the microvessel density and expression of pro-angiogenic factors. All agonists induced significant increase in macrophage tumor infiltration, with IB-MECA being most effective. This effect was accompanied by substantial changes in cytokines regulating macrophage polarization between pro-inflammatory and pro-angiogenic phenotype. Our results demonstrate an evidence that each of the analyzed receptors has a specific role in the stimulation of tumor angiogenesis and confirm significantly more multifaceted role of adenosine in its regulation than was already observed. They also reveal previously unexplored consequences to extracellular adenosine signaling depletion in recently proposed anti-CD73 cancer therapy.</p></div