Flash boiling effect on swirled injector spray angle

Abstract A swirled injector for gasoline direct injection was used to investigate the effect of fuel flash boiling on the initial angle of the spray. The hollow cone spray was injected into a constant pressure bomb filled with quiescent air. The fuel was fed at 7 MPa constant pressure to the injector. Three parameters were changed to study the effect of the injection conditions on the spray angle: fuel composition, fuel temperature and air pressure in the test bomb. The injector tip was heated up to 150°C to keep the fuel to be injected at the desired temperature. Different blends of iso-octane and n-pentane were used to obtain fuels with different bubble temperature at the same air pressure. In a reduced set of experiments, only with pure fuels, the ambient pressure was varied to change the bubble temperature independently from the fuel temperature. It was observed that, when the fuel conditions exceed the bubble point, the spray angle, measured close to the injector, becomes wider. This angle was chosen as an indicator of the flash boiling intensity. The experimental results show that the angle value is well fitted by a unique correlation if it is expressed as a function of the ratio P=Pb/ Pair between the fuel bubble pressure and the bomb pressur

Ruthenium Olefin Metathesis Complexes: Catalyst Development and Mechanistic Studies

The field of olefin metathesis has grown to include organometallic chemists who strive to develop more efficient catalysts and to understand their mechanism of activity and decomposition, synthetic organic chemists who construct complex molecules utilizing existing catalysts and continually find challenging reactions in need of more efficient catalysts, and polymer chemists who utilize current catalysts to synthesize polymers with an ever-widening array of functional groups and structures in a controlled manner. This thesis describes the exploration of new ligands for olefin metathesis catalysts and the investigation of the model compounds of olefin metathesis reaction intermediates. Chapter 2 describes the synthesis, characterization, activity and kinetic selectivity of ruthenium olefin metathesis complexes bearing cyclic (alkyl)(amino)carbenes (CAACs). The activity of phosphine-free CAAC-ruthenium complexes is significantly affected by steric interactions. By decreasing the steric bulk of the ligand, a new catalyst with activity comparable to that of existing NHC-ruthenium (N-heterocyclic carbene) complexes has been synthesized. Additionally, these complexes exhibit unusual E/Z-diastereoselectivity and ethenolysis selectivity relative to previously studied NHC-ruthenium complexes. Chapter 3 describes the exploration of 3- and 6-membered carbenes as ligands for ruthenium olefin metathesis complexes. Stable silver-cyclopropenylidene adducts were synthesized and utilized as carbene transfer reagents in the presence of ruthenium precursors. Although good conversions were observed, isolation of cyclopropenylidene-ruthenium complexes was unsuccessful. Ruthenium complexes of 6-membered ‘borazine’-like carbenes were isolated, characterized and evaluated for ring-closing metathesis activity. Chapter 4 describes the development of a model system to study ruthenium-olefin complexes relevant to the mechanism of olefin metathesis. Upon addition of the ligand precursor 1,2-divinylbenzene to (H₂IMes)(py₂)(Cl)₂Ru=CHPh (H₂IMes = 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene), two ruthenium-olefin adducts are formed. Based on ¹H NMR spectroscopy experiments and X-ray crystallographic analysis, the solution phase and solid-state structure of these complexes is assigned. Exploration of the generality of these observations through variation of the N-heterocyclic carbene ligand and the ligand precursor are also presented. Appendix 1 describes the screening of transitional-metal salts and ligands for the non-oxidative hydration of styrene. Appendix 2 describes the investigation of a prior report of intramolecular olefin hydroalkoxylation with ruthenium, copper and silver salts. Appendix 3 describes the evaluation of chiral NHCs as ligands for ruthenium and rhodium hydrosilylation catalysts. Appendix 4 describes the investigation of tin(II) halides as ligands for ruthenium olefin metathesis catalysts. Appendix 5 contains X-ray crystallographic analysis parameters of the structures presented in this thesis.</p

Ruthenium-Olefin Complexes: Effect of Ligand Variation upon Geometry

The development of a model system to study ruthenium-olefin complexes relevant to the mechanism of olefin metathesis has been reported recently. Upon addition of the ligand precursor 1,2-divinylbenzene to [RuCl2(Py)2(H2IMes)(CHPh)] (H2IMes=1,3-dimesityl-4,5-dihydroimidazol-2-ylidene), two ruthenium-olefin adducts are formed. Based on 1H NMR spectroscopy experiments and X-ray crystallographic analysis, these complexes are assigned as side-bound isomers in which the olefin and H2IMes ligands are coordinated cis to each other. Herein is reported an investigation of the generality of these observations through variation of the N-heterocyclic carbene ligand and the ligand precursor

Synthesis and reactivity of olefin metathesis catalysts bearing cyclic (alkyl) (amino) carbenes

All it's CAACed up to be! Cyclic (alkyl)(amino)carbenes (CAACs) can be used as ligands for olefin metathesis catalysis. A dramatic steric effect of the N-aryl group of the CAAC on catalyst activity was observed and utilized to develop a new catalyst with activity comparable to standard commercially available catalysts

Model Compounds of Ruthenium−Alkene Intermediates in Olefin Metathesis Reactions

The development of a model system to study ruthenium−olefin complexes relevant to the mechanism of olefin metathesis is reported. Upon addition of 1,2-divinylbenzene to (H_2IMes)(py_2)(Cl)_2Ru CHPh (H_2IMes = 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene), two ruthenium−olefin adducts are formed. On the basis of ^1H NMR spectroscopy experiments and X-ray crystallographic analysis, these complexes are assigned as side-bound isomers in which the olefin and H_2IMes ligands are coordinated cis to each other. The dynamic interconversion of these two ruthenium complexes was determined to have a barrier of 19.1 ± 0.1 kcal/mol

Kinetic Selectivity of Olefin Metathesis Catalysts Bearing Cyclic (Alkyl)(Amino)Carbenes

The evaluation of ruthenium olefin metathesis catalysts 4–6 bearing cyclic (alkyl)(amino)carbenes (CAACs) in the cross-metathesis of cis-1,4-diacetoxy-2-butene (7) with allylbenzene (8) and the ethenolysis of methyl oleate (11) is reported. Relative to most NHC-substituted complexes, CAAC-substituted catalysts exhibit lower E/Z ratios (3:1 at 70% conversion) in the cross-metathesis of 7 and 8. Additionally, complexes 4–6 demonstrate good selectivity for the formation of terminal olefins versus internal olefins in the ethenolysis of 11. Indeed, complex 6 achieved 35 000 TONs, the highest recorded to date. CAAC-substituted complexes exhibit markedly different kinetic selectivity than most NHC-substituted complexes

Participation in Decision Making as a Property of Complex Adaptive Systems: Developing and Testing a Measure

Objectives. To (1) describe participation in decision-making as a systems-level property of complex adaptive systems and (2) present empirical evidence of reliability and validity of a corresponding measure. Method. Study 1 was a mail survey of a single respondent (administrators or directors of nursing) in each of 197 nursing homes. Study 2 was a field study using random, proportionally stratified sampling procedure that included 195 organizations with 3,968 respondents. Analysis. In Study 1, we analyzed the data to reduce the number of scale items and establish initial reliability and validity. In Study 2, we strengthened the psychometric test using a large sample. Results. Results demonstrated validity and reliability of the participation in decision-making instrument (PDMI) while measuring participation of workers in two distinct job categories (RNs and CNAs). We established reliability at the organizational level aggregated items scores.We established validity of the multidimensional properties using convergent and discriminant validity and confirmatory factor analysis. Conclusions. Participation in decision making, when modeled as a systems level property of organization, has multiple dimensions and is more complex than is being traditionally measured. Managers can use this model to form decision teams that maximize the depth and breadth of expertise needed and to foster connection among them

COMPARATIVE STUDY ON EFFECT OF SLOW AND FAST PHASED PRANAYAMA ON QUALITY OF LIFE AND PAIN IN PHYSIOTHERAPY GIRLS WITH PRIMARY DYSMENORRHOEA: RANDO-MIZED CLINICAL TRIAL

Objective: Few studies have been done on pranayama as therapy to improve pain and quality of life for primary dysmenorrhoea. Hence, this study is aimed at understanding the effect of slow and fast pranayama on primary dysmenorrhoea among Physiotherapy girl students. Methods: Unmarried girls (n=90) under the age group of 18-25 with primary dysmenorrhoea were randomly assigned to the study, Group A (n=45) Group B (n=45). Moos menstrual distress questionnaire (MMDQ), Numerical pain rating scale for pain, Quality of life scale by American chronic pain association were administered at baseline, after 1 st menstrual cycle and follow-up after 2 nd menstrual cycle. Group A was subjected to slow pranayama (Nadi Shodhan) and Group B was subjected to fast pranayama (Kapalbhati). Result: Significant (P&lt;0.0001) improvement in quality of life and pain scores after intervention was seen in Group A (Nadi Shodan) as compared to Group B (Kapalbhati) . Prevalence of Primary Dysmenorrhoea was found to be high between the age group of 18-22. Conclusion: With Slow pranayama (Nadi Shodhan) the quality of life and pain scores improved when compared to Fast pranayama (Kapalbhati) indicating the benefits of Slow pranayama on Primary Dysmenorrhoea. Pranayama improves quality of life and reduces absenteeism and stress levels, so it should be implemented in college students to augment their menstrual wellbeing and should be inculcated as a routine practice to improve quality of life

Bovine Tuberculosis at the Wildlife-Livestock-Human Interface in Hamer Woreda, South Omo, Southern Ethiopia

Bovine tuberculosis (BTB) is endemic in cattle in the Ethiopian Highlands but no studies have been done so far in pastoralists in South Omo. This study assessed the prevalence of bovine tuberculosis (BTB) at an intensive interface of livestock, wildlife and pastoralists in Hamer Woreda (South Omo), Ethiopia. A cross-sectional survey including a comparative intradermal skin testing (CIDT) was conducted in 499 zebu cattle and 186 goats in 12 settlements. Sputum samples from 26 symptomatic livestock owners were cultured for TB. Fifty-one wildlife samples from 13 different species were also collected in the same area and tested with serological (lateral flow assay) and bacteriological (culture of lymph nodes) techniques. Individual BTB prevalence in cattle was 0.8% (CI: 0.3%–2%) with the >4 mm cut-off and 3.4% (CI: 2.1%–5.4%) with the >2 mm cut-off. Herd prevalence was 33.3% and 83% when using the >4 and the >2 mm cut-off respectively. There was no correlation between age, sex, body condition and positive reactors upon univariate analysis. None of the goats were reactors for BTB. Acid fast bacilli (AFB) were detected in 50% of the wildlife cultures, 79.2% of which were identified as Mycobacterium terrae complex. No M. bovis was detected. Twenty-seven percent of tested wildlife were sero-positive. Four sputum cultures (15.4%) yielded AFB positive colonies among which one was M. tuberculosis and 3 non-tuberculous mycobacteria (NTM). The prevalence of M. avium-complex (MAC) was 4.2% in wildlife, 2.5% in cattle and 0.5% in goats. In conclusion, individual BTB prevalence was low, but herd prevalence high in cattle and BTB was not detected in goats, wildlife and humans despite an intensive contact interface. On the contrary, NTMs were highly prevalent and some Mycobacterium spp were more prevalent in specific species. The role of NTMs in livestock and co-infection with BTB need further research