Investigations on Deposit Formation in the Holes of Diesel Injector Nozzles

Current developments in fuels and emissions regulations are resulting in an increasingly severe operating environment for diesel fuel injection systems. The formation of deposits within the holes or on the outside of the injector nozzle can affect the overall system performance. The rate of deposit formation is affected by a number of parameters, including operating conditions and fuel composition. For the work reported here an accelerated test procedure was developed to evaluate the relative importance of some of these parameters in a high pressure common rail fuel injection system. The resulting methodology produced measurable deposits in a custom made injector nozzle on a single cylinder engine. The results indicate that fuels containing 30%v/v and 100% Fatty Acid Methyl Ester (FAME), that does not meet EN 14214 produced more deposit than an EN590 petroleum diesel fuel. Overall, the addition of zinc to the fuel had the biggest effect on deposit formation and resulted in a 12.2% decrease in Indicated Mean Effective Pressure (IMEP). The effects of zinc were unexpectedly reduced when it was added to fuel containing 30%v/v biodiesel. Reducing the common-rail pressure with 30%v/v biodiesel (no added zinc) increased the loss in IMEP. Raising the air and fuel temperatures by 40°C and 30°C respectively showed no bigger loss in IMEP. The results indicate that deposit formation may continue after engine shut down. © 2011 Society of Automotive Engineers of Japan, Inc. and SAE International

Deposit Formation in the Holes of Diesel Injector Nozzles: A Critical Review

Current developments in fuels and emissions regulations are resulting in increasingly severe operating environment for the injection system. Formation of deposits within the holes of the injector nozzle or on the outside of the injector tip may have an adverse effect on overall system performance. This paper provides a critical review of the current understanding of the main factors affecting deposit formation. Two main types of engine test cycles, which attempt to simulate field conditions, are described in the literature. The first type involves cycling between high and low load. The second involves steady state operation at constant speed either at medium or high load. A number of influences on the creation of deposits are identified. This includes fouling through thermal condensation and cracking reactions at nozzle temperatures of around 300°C. Also the design of the injector holes is an influence, because it can influence cavitation. The implosion of cavitation bubbles is believed to limit nozzle deposits. Field and laboratory tests showed that small amounts (around 1ppm) of zinc tend to increase the formation of deposits and are therefore another influence. But it is not clear whether zinc acts catalytically to accelerate deposit formation or if it becomes part of the solid deposits. Bio-diesel has been observed to lead to higher deposit formation in the injector nozzle. The chemical and physical processes that lead to deposit formation are not known or well understood, due to their complexity. A physical mechanism put forward focuses on the role of the residual fuel that remains in the nozzle holes after the end of the injection process. © 2008 SAE International

From ether to acid: a plausible degradation pathway of glycerol dialkyl glycerol tetraethers

Glycerol dialkyl glycerol tetraethers (GDGTs) are ubiquitous microbial lipids with extensive demonstrated and potential roles as paleoenvironmental proxies. Despite the great attention they receive, comparatively little is known regarding their diagenetic fate. Putative degradation products of GDGTs, identified as hydroxyl and carboxyl derivatives, were detected in lipid extracts of marine sediment, seep carbonate, hot spring sediment and cells of the marine thaumarchaeon Nitrosopumilus maritimus. The distribution of GDGT degradation products in environmental samples suggests that both biotic and abiotic processes act as sinks for GDGTs. More than a hundred newly recognized degradation products afford a view of the stepwise degradation of GDGT via (1) ether bond hydrolysis yielding hydroxyl isoprenoids, namely, GDGTol (glycerol dialkyl glycerol triether alcohol), GMGD (glycerol monobiphytanyl glycerol diether), GDD (glycerol dibiphytanol diether), GMM (glycerol monobiphytanol monoether) and bpdiol (biphytanic diol); (2) oxidation of isoprenoidal alcohols into corresponding carboxyl derivatives and (3) chain shortening to yield C39and smaller isoprenoids. This plausible GDGT degradation pathway from glycerol ethers to isoprenoidal fatty acids provides the link to commonly detected head-to-head linked long chain isoprenoidal hydrocarbons in petroleum and sediment samples. The problematic C80to C82tetraacids that cause naphthenate deposits in some oil production facilities can be generated from H-shaped glycerol monoalkyl glycerol tetraethers (GMGTs) following the same process, as indicated by the distribution of related derivatives in hydrothermally influenced sediments.Seventh Framework Programme (European Commission) (ERC Grant 247153

The bacteriohopanepolyol inventory of novel aerobic methane oxidising bacteria reveals new biomarker signatures of aerobic methanotrophy in marine systems

Aerobic methane oxidation (AMO) is one of the primary biologic pathways regulating the amount of methane (CH4) released into the environment. AMO acts as a sink of CH4, converting it into carbon dioxide before it reaches the atmosphere. It is of interest for (paleo)climate and carbon cycling studies to identify lipid biomarkers that can be used to trace AMO events, especially at times when the role of methane in the carbon cycle was more pronounced than today. AMO bacteria are known to synthesise bacteriohopanepolyol (BHP) lipids. Preliminary evidence pointed towards 35-aminobacteriohopane-30,31,32,33,34-pentol (aminopentol) being a characteristic biomarker for Type I methanotrophs. Here, the BHP compositions were examined for species of the recently described novel Type I methanotroph bacterial genera Methylomarinum and Methylomarinovum, as well as for a novel species of a Type I Methylomicrobium. Aminopentol was the most abundant BHP only in Methylomarinovum caldicuralii, while Methylomicrobium did not produce aminopentol at all. In addition to the expected regular aminotriol and aminotetrol BHPs, novel structures tentatively identified as methylcarbamate lipids related to C-35 amino-BHPs (MCBHPs) were found to be synthesised in significant amounts by some AMO cultures. Subsequently, sediments and authigenic carbonates from methane-influenced marine environments were analysed. Most samples also did not contain significant amounts of aminopentol, indicating that aminopentol is not a useful biomarker for marine aerobic methanotophic bacteria. However, the BHP composition of the marine samples do point toward the novel MC-BHPs components being potential new biomarkers for AMO

Haematological and biochemical profiles during the puerperium in dairy cows – Short communication

The main aim of the current study was to assess the prevalence of anaemia in Holstein dairy cows during the puerperium, and the haematological and biochemical profile of dairy cows with and without anaemia. The study was conducted in seven dairy herds in São Paulo State, Brazil. The evaluated sample comprised a total of 336 Holstein cows. Blood samples were collected at postpartum day 25 ± 3. Haematological analysis included white blood cell, red blood cell and platelet count, haematocrit value, haemoglobin concentration, mean corpuscular volume, mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration. The biochemical profile encompassed cholesterol, non-esterified fatty acids, β-hydroxybutyrate, albumin, globulin, fibrinogen, calcium and total bilirubin concentrations. The prevalence of anaemia was 16.3% in all herds, and this was not affected by clinical diseases, milk production, parity and body score condition. Moreover, anaemic cows had lower red blood cell count, haematocrit, haemoglobin, serum cholesterol and calcium concentrations and higher white blood cell and platelet counts, mean corpuscular haemoglobin, red cell distribution width, non-esterified fatty acids, β-hydroxybutyrate, fibrinogen and globulin concentrations when compared with non-anaemic cows. The results indicate changes in energy balance and an inflammatory process in anaemic cows

Thermoregulatory Responses of Heat Acclimatized Buffaloes to Simulated Heat Waves

Climate change is seen as a significant threat to the sustainability of livestock production systems in many parts of the world, particularly in tropical regions. Extreme meteorological events can result in catastrophic production and death of livestock. Heat waves in particular can push vulnerable animals beyond their survival threshold limits. However, there is little information about buffalo responses to sudden changes in the thermal environment, specifically the heat waves. This study aimed to quantify the thermoregulatory and blood biochemical responses of heat-acclimatized buffaloes to a simulated heat wave. The experiment was designed in a climatic chamber with two periods of 4 days each. Twelve heat acclimated buffalo heifers aged 18 months were used. The climatic chamber environment was set as follows: 4-day period (P1) simulating the same weather conditions of a summer in humid tropical climate used as a baseline, with daily cycle with Ta and RH at 27 ± 1 °C and 76% from 0600 h to 1900 h and 24 ± 1 °C and 80% from 1900 h to 0600 h, and 4-day period (P2), simulating a daily heat wave cycle, from 0600 h to 1900 h with Ta and RH kept at 36 °C and 78% and from 1900 h to 0600 h, 27 °C and 74%. All animals were subject to both treatments and data were analyzed by a repeated measure analysis of variance, with post-hoc pooling comparison performed by Tukey’s test. In P2, there was observed a significant increase in respiratory frequency (p < 0.01), found four times in P1. The sweating rates were quite high in both periods; still, there were significant increases in P2 compared to P1 (p < 0.01) (4931 and 3201 g/m2/h, respectively). A slight but significant increase in rectal temperature was observed during the day (p < 0.01), with a rising until 1900 h. The simulated heat wave in P2 did not affect the values of the erythrogram or leukogram, excluding the significant reduction in K+ (p < 0.05). The low heat storage and the subsequent fast and full recovery of the thermal balance late afternoon appear to be related to the high sweating rate values. The massive sweating rate emphasizes its relevance in the maintenance of buffalo homeothermy. The absence of changes in hematological parameters has revealed the considerable physiological resilience of buffaloes toward simulated heat wave

Dermatophylosis in Santa Inês sheep from Distrito Federal

Relataram-se quatro casos de dermatofilose em ovinos da raça Santa Inês, no período de um ano. Microscopicamente observaram-se filamentos na forma de "trilho de bonde" e zoósporos nos quatro casos. A tentativa do isolamento do microrganismo foi realizada por meio do método de Haalstra e em apenas um caso obteve-se sucesso, observando-se colônias de aparência lisa, formato circular, cor amarelada e hemolítica em ágar sangue. O exame direto com coloração de Gram mostrou-se um método bastante eficiente na confirmação da presença do microrganismo afetando a epiderme em razão da morfologia típica do agente.Four cases of dermatophylosis were reported in Santa Inês sheep in a study period of one year. Microscopically, septate filaments and coccoid forms zoospores were observed. Attempts to isolate the microorganisms were accomplished using Haastra's method and it was successful in only one case. Dermatophilus congolensis samples have grown on blood agar, colonies where hemolytic, small, round and pigmentation vary from yellow to orange. The gram staining method was efficient to confirm the presence of the microorganism affecting the epidermis due to typical morphology of the agent