Thermal stability of linear siloxanes and their mixtures

The working fluid thermal stability is one of the crucial features of an effective organic Rankine cycle. Hexamethyldisiloxane (MM -C6H18OSi2) and octamethyltrisiloxane (MDM -C8H24O2Si3) are siloxane fluids currently exploited in high temperature organic Rankine cycles. However, data about their thermal stability are scarce or absent in literature. This manuscript presents a study of their behavior and decomposition at operating temperatures in the range 270 - 420 degrees C. The assessment of thermal stability can be performed with several methods, which are either based on pressure anomalous variation in isothermal stresses or on the deviation of the saturation curves experimentally obtained before and after the fluid is thermally stressed. An enhanced method is proposed here, based on chemical analysis of both vapor and liquid phases of the sample before and after it is subjected to thermal stress. A comparison of the pre-and post-stress vapor-liquid equilibrium curve complements the analysis. Results proved a higher stability for MM than for MDM. Moreover, due to the current interest in applying mixtures in organic Rankine cycles, an equimolar mixture of MM and MDM was also tested, which exhibit a behavior that appears to be different from the simple superimposition of pure fluid ones

Development of a Background-Oriented Schlieren Technique with Telecentric Lenses for Supersonic Flow

Background oriented schlieren (BOS) is a quantitative optical technique which exploits light deflection occurring in non-homogeneous transparent media. It allows to indirectly measure the density gradients by analysing the apparent displacement of features of a background pattern when imaged through the investigated flow. Thanks to its simple set-up and to the consolidated data reduction technique based on cross-correlation algorithms the BOS technique has progressively attracted the interest of the researchers. In this work a BOS system using a telecentric lens system has been set up in order to improve measurement accuracy and to avoid 3D effects arising from using conventional entocentric lenses. The design of the telecentric lens system is reported along with an analysis of its performance in term of spatial resolution. Some preliminary tests on a supersonic flows are also reported

Intestinal helminths of red foxes (Vulpes vulpes) in north-west Italy

SummaryA total of 180 foxes (Vulpes vulpes) from an area scarcely investigated of north-west Italy, were examined for intestinal helminths using sedimentation and counting technique (SCT). Faecal samples were submitted to centrifugation with 50 % zinc sulphate used as flotation solution.No fox was found completely negative for intestinal helminths. The most frequently identified nematodes were Uncinaria stenocephala (70.0 %), Molineus legerae (27.2 %), Toxocara canis (26.7 %), Toxascaris leonina (25.6 %), Trichuris vulpis (21.1 %), Aonchotheca putorii (8.9 %), Pterygodermatites affinis (5.6 %). Genus Mesocestoides (81.7 %), family Dilepididae (29.4 %) and Taenia spp. (8.3 %) were the most prevalent cestodes. All foxes were negative for E. multilocularis and E. granulosus. In two foxes trematodes belonging to the family Plagiorchidae were found.The study highlighted that foxes are hosts of intestinal helminths of veterinary and medical importance which may be transmitted to dogs and humans

Anisakis spp. larvae in different kinds of ready to eat products made of anchovies (Engraulis encrasicolus) sold in Italian supermarkets

In this study the occurrence of visible anisakid larvae in semi-preserved anchovy products sold on the Italian market was investigated. Totally, 107 ready to eat products (33 salted-ripened, 49 in oil and 25 marinated) were sampled. Each sample was digested, then the digested material was observed under natural and UV light. Parasites were counted, collected and microscopically identified to genus level. A representative subset was molecularly identified using the cox2 gene. At least one visible Anisakis sp. larva was found in 54.2% of the total 107 products analysed and totally 1283 dead larvae were collected. Anisakis sp. larvae were found in all the 33 salted products and 1139 (88.8%) larvae were collected, with a range of 1â105 parasites per product. Larval density per gram was 0.13. Anisakis sp. larvae were found in 49.0% of the products in oil and 143 (11.1%) larvae were isolated, with a range of 0â28 and a density of 0.03. Only 1 larva was found in the 25 marinated products (4.0%, density 0.00). A highly significant difference between all the product categories in respect of number of larvae per product, frequency of products contaminated by at least one larva and larval density per gram was found. Within the subset of larvae molecularly analysed (n = 122), 92 (75.4%) were identified as A. pegreffii and 30 (24.6%) as A. simplex. This study showed that semi-preserved anchovy products heavily contaminated with Anisakis spp. larvae reach the market. Beyond the negligible risk for anisakidosis, the presence of dead visible parasites may cause immediate rejection in consumers. In addition, the potential risk related to allergic reactions in sensitized individuals needs to be further assessed. In order to avoid commercialization of obviously contaminated products, fresh anchoviesâ batches intended for the production of such products should be accurately selected by the processing industry applying inspection methods

Calodium hepaticum (Nematoda: Capillaridae) in a red fox (Vulpes vulpes) in Italy with scanning electron microscopy of the eggs

Calodium hepaticum (Bancroft, 1893) Moravec, 1982 (syn. Capillaria hepatica) is a cosmopolitan capillariid nematode, infecting mainly rodents and occasionally other mammals, including humans. Reports of C. hepaticum in canids are rare and the present one is, to the best of our knowledge, the first reported case in a red fox (Vulpes vulpes Linnaeus) in Italy. Scanning electron microscopy (SEM) examination of the eggs of C. hepaticum allowed a precise description of the egg morphology, which is one of the most relevant specific characteristics of capillariid nematodes. The egg shell showed a fibrous beam-like network which differs from that of the eggs of closely related trichinelloid species. This characteristic can be useful especially in case of spurious infection, when misdiagnosis among different trichinelloids species can occur

Design and commissioning of a thermal stability test-rig for mixtures as working fluids for ORC applications

Abstract A novel test-rig for studying the thermal stability of mixtures as working fluids for ORC applications was designed and commissioned at the Laboratory of Compressible-fluid dynamics for Renewable Energy Applications (CREA) of Politecnico di Milano, in collaboration with the University of Brescia. The set-up is a standard one, in which a vessel containing the fluid under scrutiny is placed in a vertical oven for ~ 100 hours at a constant temperature T = Tstress. During the test, the pressure P is monitored to detect thermal decomposition of the fluid. After the test, the vessel is placed in a controlled thermal bath, where the pressure is measured at different value of the temperature T, with

Survey on the presence of bacterial and parasitic zoonotic agents in the feces of wild birds

Wild avifauna may act as fecal source of bacterial and parasitic pathogens for other birds and mammals. Most of these pathogens have a relevant impact on human and livestock health which may cause severe disease and economic loss. In the present study, the fecal samples collected from 121 wild birds belonging to 15 species of the genera Anas, Tadorna, Fulica, Arddea, Larus, Falco, Athene, Accipiter, and Columba were submitted to bacteriological and molecular analyses to detect Brucella spp., Coxiella burnetii, Mycobacterium spp., Salmonella spp., Cryptosporidium spp., Giardia spp., and microsporidia. Four (3.3%) animals were positive for one pathogen: one Anas penelope for C. burnetii, one Larus michahellis for S. enterica serovar Coeln, and two Columba livia for Encephalitozoon hellem. Although the prevalence rates found in the present survey were quite low, the obtained re-sults confirm that wild birds would be the a potential fecal source of bacterial and parasitic zoonotic pathogens which sometimes can also represent a severe threat for farm animals

Apicomplexan protozoa responsible for reproductive disorders: Occurrence of dna in blood and milk of donkeys (equus asinus) and minireview of the related literature

Donkeys may be susceptible to many pathological agents and may act as carriers of pathogens for other animal species and humans. This study evaluated the occurrence of potentially abortifacient apicomplexan protozoa DNA in blood and milk samples collected at different time periods during lactation (1, 6, and 10 months) from 33 healthy dairy jennies. A total of 73 blood and 73 milk samples were used for DNA extraction and analysis. Blood specimens from 11/33 (33%) jennies scored positive for Theileria equi, while milk samples scored negative. Blood and milk of 3/33 jennies yielded DNA of Toxoplasma gondii at 6 months (n. 1) and 10 months (n. 2) after parturition. Neospora caninum DNA was found in four milk and in five blood samples only at one month after parturition. This study is the first report about the presence of N. caninum DNA in milk of naturally infected jennies. Moreover, the excretion of N. caninum DNA in some of these jennies at 30 days from the parturition may suggest a possible occurrence of an endogenous cycle, while the presence of T. gondii DNA in the milk collected at 6 and 10 months after parturition may be suggestive of a discontinuous excretion

First recovery of bird acanthocephalan Sphaerirostris lanceoides in an Eurasian badger (Meles meles) in Italy

Esemplari di cistacanti parzialmente e completamente evertiti dell'acantocefalo Sphaerirostris lanceoides sono stati rilevati nell'intestino di 1 tra 5 tassi (Meles meles) raccolti in Italia e già deceduti al momento del loro ritrovamento. Questa è la prima segnalazione di S. lanceoides nel tasso