Numerical investigation of oil injection in a Roots blower operated as expander

The adoption of positive displacement machines as expanders in Organic Rankine Cycles (ORCs) is increasingly common, especially in the low to medium power range. At the same time, these devices often serve as compressor in Vapor-Compression Refrigeration Systems. In both cases, the application of Computation Fluid Dynamics (CFD) to optimize such machines has become an integrated tool in the design process. As a consequence, several challenges associated with the numerical simulation have to be taken into account. For example, the modeling of the gap represents a challenge for the stability of the numerical analysis. The dynamic of the process, combined with deformations of the clearances and of the working chamber has to be considered with extra care. To raise the efficiency of the machine, oil is typically injected. Its numerical modeling imply an extra challenge in the simulation of the actual operation of the machine. The present work is mainly focused on the multi-phase nature of the flow, with a particular analysis of the lubricant oil injected. In this work, a two-lobe Roots blower operated as expander has been simulated with the open-source software OpenFOAM-v1812, using the SCORG-V5.2.2. This analysis highlights the areas that are affected the most by the oil presence in order to highlight the sealing effect it provides

Man, environment and ozone

U radu se razglaba o ozonu kao prirodnom sastojku atmosfere, nepovoljnu učinku smanjenja ozonskog omotača te porastu koncentracije ozona u troposferi. Dan je prikaz pojedinih industrijskih grana gdje je ozon prisutan uz osvrt na ambijentalnu izloženost. Također se razglaba o akutnoj i kroničnoj toksičnosti ozona te patofiziološkim mehanizmima djelovanja ozona na tkiva, napose na respiratorni sustav. Spominju se mjerenja ozona u Hrvatskoj s kraja 19. stoljeća te ona započeta nakon 1975. koja i danas traju.Ozone is a naturally occurring gas, formed in the trimolecular reaction of oxygen atoms with molecular oxygen. Its strong absorption in the UV region provides protection from excessive irradiation of the Earth\u27s surface. Occupational exposure to ozone involves electric are welding, mercury vapour lamps, office photocopy machines. X-ray generators and other high voltage electrical equipment, water purification and bleaching. Ozone is the most abundant oxidant in the photochemical smog. The lung cell injury induced by ozone involves a complex biochemical mechanism which is due to free radical generation. Moderate exposure produces upper respiratory tract symptoms and eye irritation, severe acute exposure results in pulmonary oedema. Measurements of atmospheric ozone concentrations in Croatia began at the end of the 19th century; continuous monitoring has been earned out since 1975

Polymethyl – Methacrylate Implants in Forehead and Supraorbital Arches Reconstruction: Retrospective Study

Frontobasal injuries and some other diseases of frontal sinuses sometimes require radical surgery with the obliteration of the sinus. A cosmetic correction of the forehead and supraorbital arches has to be performed after such a procedure. Nowadays, there is a wide choice of alloplastic materials on the market. We tried polymethyl methacrylate implants in correction of the exterior appearance of the forehead and supraorbital arches and followed the behaviour of the implants up to 25 years after surgery. The result was 18 (94,7%) successful implantations and one failure (5,3%) with a mild sagging of the borders of the implant. Polymethyl-methacrylate proved pliable for work and modelling, not invasive for the organism and stable. In conclusion, the cure of some frontobasal injuries and diseases with the first surgical step followed by cosmetic correction of the forehead and supraorbital arches (2nd surgical step) using this alloplastic material provides a safe, durable and aesthetically satisfactory solution for the patient

Impact of maritime transport on particulate matter concentrations and chemical compositions in four port-cities of the Adriatic/Ionian area: an overview of the results of POSEIDON project

Pollutant emissions from ships and harbour activities constitute an important source of pollution of coastal areas with potential influences on the climate and the health of their inhabitants. A recent review (Viana et al., 2014) shows that these emissions could have an important impact on the Mediterranean and that there is a lack of data for the Eastern and South-Eastern part of this area. This work presents an analysis of the impact of ship emissions to atmospheric particle concentrations (PM) in four important port-cities (Patras Greece, Brindisi and Venice Italy, and Rijeka Croatia) of the Adriatic/Ionian area. The study was performed within the POSEIDON project (Pollution monitoring of ship emissions: an integrated approach for harbours of the Adriatic basin, funded within the MED Programme 2007-2013). The study uses an integrated approach using emission inventories, dispersion modelling and measurements taken at high temporal resolution (1 min) and low temporal resolution for chemical characterization of PM. The emission inventories of the four port-cities show that ships contribute between 11.7% and 31.0% of the total PM emissions being a source locally comparable with road traffic (ranging between 11.8% and 26.6%). The source apportionment using the receptor model PMF showed and oil combustion source (that includes ship emissions), characterized by V and Ni, in Brindisi, Venice and Rijeka with V/Ni ratio ranging between 1.4 and 4.2 indicating local differences in chemical profiles of the emissions. The V concentrations were used to evaluate the contributions of primary ship emissions to PM (Agrawal et al., 2009) that resulted between 1.3% and 2.8%. The contribution to secondary sulphate was 11% of PM2.5 in Brindisi (Cesari et al., 2014). The analysis of high-temporal resolution measurements taken near the harbour areas of Venice, Patras and Brindisi showed a contribution of ship emissions to PM2.5 varying between 3.5% and 7.4%. The relative contribution to particle number concentrations (PNC) was larger at all sites (between 6% and 26%). This demonstrates that ship particulate missions include mainly small and ultrafine particles. The trend of the impact of passenger ships primary emissions to PM2.5 concentrations in Venice between 2007 and 2012 showed a decrease from 7% (+-1%) to 3.5% (+-1%) even if the gross tonnage of ship traffic increased in the same period by 47% (Contini et al., 2015). This was a consequence of the use of low-sulphur content fuels due to the application of local mitigation strategies and of the European Directive 2005/33/EC. The WRF-CAMx modeling system was applied over the Central and Eastern Mediterranean so as to identify the air quality impact of ship emissions. The zero-out modelling method was implemented involving model simulations performed while including and omitting the ship emissions. The results for both gaseous and particulate pollutant concentrations generally show a fairly good agreement with observations at the areas under study. Agrawal et al., 2009. Environmental Science and Technology 43, 5398-5402. Cesari et al., 2014. Science of the Total Environment 497-498, 392-400. Contini et al., 2015. Atmospheric Environment 102, 183-190. Viana et al., 2014. Atmospheric Environment 90, 96-105

Multi-genome identification and characterization of chlamydiae-specific type III secretion substrates: the Inc proteins

<p>Abstract</p> <p>Background</p> <p><it>Chlamydiae </it>are obligate intracellular bacteria that multiply in a vacuolar compartment, the inclusion. Several chlamydial proteins containing a bilobal hydrophobic domain are translocated by a type III secretion (TTS) mechanism into the inclusion membrane. They form the family of Inc proteins, which is specific to this phylum. Based on their localization, Inc proteins likely play important roles in the interactions between the microbe and the host. In this paper we sought to identify and analyze, using bioinformatics tools, all putative Inc proteins in published chlamydial genomes, including an environmental species.</p> <p>Results</p> <p>Inc proteins contain at least one bilobal hydrophobic domain made of two transmembrane helices separated by a loop of less than 30 amino acids. Using bioinformatics tools we identified 537 putative Inc proteins across seven chlamydial proteomes. The amino-terminal segment of the putative Inc proteins was recognized as a functional TTS signal in 90% of the <it>C. trachomatis </it>and <it>C. pneumoniae </it>sequences tested, validating the data obtained <it>in silico</it>. We identified a <it>macro </it>domain in several putative Inc proteins, and observed that Inc proteins are enriched in segments predicted to form coiled coils. A surprisingly large proportion of the putative Inc proteins are not constitutively translocated to the inclusion membrane in culture conditions.</p> <p>Conclusions</p> <p>The Inc proteins represent 7 to 10% of each proteome and show a great degree of sequence diversity between species. The abundance of segments with a high probability for coiled coil conformation in Inc proteins support the hypothesis that they interact with host proteins. While the large majority of Inc proteins possess a functional TTS signal, less than half may be constitutively translocated to the inclusion surface in some species. This suggests the novel finding that translocation of Inc proteins may be regulated by as-yet undetermined mechanisms.</p

Surface Energy Budgets of Arctic Tundra During Growing Season

This study analyzed summer observations of diurnal and seasonal surface energy budgets across several monitoring sites within the Arctic tundra underlain by permafrost. In these areas, latent and sensible heat fluxes have comparable magnitudes, and ground heat flux enters the subsurface during short summer intervals of the growing period, leading to seasonal thaw. The maximum entropy production (MEP) model was tested as an input and parameter parsimonious model of surface heat fluxes for the simulation of energy budgets of these permafrost‐underlain environments. Using net radiation, surface temperature, and a single parameter characterizing the thermal inertia of the heat exchanging surface, the MEP model estimates latent, sensible, and ground heat fluxes that agree closely with observations at five sites for which detailed flux data are available. The MEP potential evapotranspiration model reproduces estimates of the Penman‐Monteith potential evapotranspiration model that requires at least five input meteorological variables (net radiation, ground heat flux, air temperature, air humidity, and wind speed) and empirical parameters of surface resistance. The potential and challenges of MEP model application in sparsely monitored areas of the Arctic are discussed, highlighting the need for accurate measurements and constraints of ground heat flux.Plain Language SummaryGrowing season latent and sensible heat fluxes are nearly equal over the Arctic permafrost tundra regions. Persistent ground heat flux into the subsurface layer leads to seasonal thaw of the top permafrost layer. The maximum energy production model accurately estimates the latent, sensible, and ground heat flux of the surface energy budget of the Arctic permafrost regions.Key PointThe MEP model is parsimonious and well suited to modeling surface energy budget in data‐sparse permafrost environmentsPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150560/1/jgrd55584.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150560/2/jgrd55584_am.pd

Genes of nuclear encoded mitochondrial proteins: evidence for a variant of the 3' splice-site consensus sequence.

The introns of animal nuclear genes and of viral genes encoding protein possess at their 3' splice-site the consensus sequence (CT)11NTCAG (Mount, S.M. (1982) Nucl. Acids Res. 10, 459-472; Green, M.R. (1986) Ann. Rev. Genet. 20, 671-708). However, the total 39 introns of the 5 imported mitochondrial proteins of higher eucaryotes whose gene structure has been determined to date show a predominance of 44% for base T at position -4. Apparently, a variant consensus sequence, i.e. (CT)11TTCAG, characterizes the genes of nuclear encoded mitochondrial proteins

Disease intensity of some tomato viroses in Serbia

In this paper rye present the data on the disease intensity of the tomato plants grown in glass and plastic-houses, and in the open field. The infection was caused by the following viruses: Tomato mosaic virus (ToMV), Tobacco mosaic virus (TMV), Tomato spotted wilt virus (TSWV), Alfalfa mosaic virus (AMV), Potato virus X (PVX), Potato virus Y (PVY), Tomato black ring virus (TBRV), Tomato ringspot virus (ToRSV), Tomato aspermy virus (TAV), and Cucumber mosaic virus (CMV). These viruses represented most frequent tomato pathogens in Serbia. According to the obtained results, it could be concluded that 92.94 % of the rested tomato plants grown in glass and plastic-houses, and 89.82 % grown in the open field were infected by one of the above viruses. Most of the plant samples were infected by two or more viruses. The most frequent viruses - tomato pathogens in Serbia were ToMV, PVY and TMV

Tools for designing amphipathic helical antimicrobial peptides

Methods are described for the design of amphipathic helical AMPs, to improve potency and/or increase selectivity with respect to host cells. One method is based on the statistical analysis of known helical AMPs to derive a sequence template and ranges of charge, hydrophobicity, and amphipathicity (hydrophobic moment) values that lead to broad-spectrum activity, but leaves optimization for selectivity to subsequent rounds of SAR determinations. A second method uses a small database of anuran AMPs with known potency (MIC values vs. E. coli) and selectivity (HC50 values vs. human erythrocytes), as well as the concept of longitudinal moment, to suggest sequences or sequence variations that can improve selectivity. These methods can assist in the initial design of novel AMPs with useful properties in vitro, but further development requires knowledge-based decisions and a sound prior understanding of how structural and physical attributes of this class of peptides affect their mechanism of action against bacteria and host cells