RESUMO
Recently, ammonia (NH3), which has a higher energy density than hydrogen, has gained attention for zero-carbon emission goals in the transportation sector. However, in a conventional internal combustion engine (ICE), NH3 combustion mechanism is still under investigation. In this paper, to further expand the knowledge on the adoption of NH3 in ICEs, authors conducted NH3/gasoline co-combustion experiments in a modified, 17.7:1 compression ratio, naturally aspirated spark-assisted CI engine with sub-chamber. The sub-chamber was chosen in order to enhance the combustion speed of NH3. In addition, the sub-chamber was equipped with glow and spark plugs to overcome the high auto-ignition temperature of NH3. Engine performance and NOX emissions were studied under three different intake air temperatures. During the experiments, NH3 content was increased gradually where the engine was run under lean conditions. Although higher NH3 content was achieved compared to our previous work, increasing the intake air temperature resulted in decreased charging efficiency. In addition, corrosion was found on the piston ring after 120 h of operation, negatively affecting the engine performance. Furthermore, NH3/gasoline co-combustion duration was shortened drastically with the influence of the sub-chamber, where the longest combustion duration under the present conditions was found to be 17°CA.
RESUMO
OBJECTIVES: The aim of this study was to retrospectively evaluate the signalment, treatment, surgical technique and outcomes for feline symblepharon. METHODS: A retrospective medical record review and standardized grading of clinical descriptions and photographs was undertaken. RESULTS: Forty kittens (54 eyes) aged 3-46 weeks had symblepharon of five types in various combinations: eyelid deformation (24 kittens; 32 eyes); ankyloblepharon (four kittens; four eyes); conjunctiva-to-conjunctiva (11 kittens; 12 eyes); third eyelid-to-conjunctiva (24 kittens; 29 eyes); and corneoconjunctival adhesions (14 kittens; 16 eyes). At initial presentation, 23 (43%) eyes were affected by one type of symblepharon, 25 (46%) eyes by two types and six (11%) eyes by three types; 11 (20%) corneas were ulcerated. Twenty-four (44%) eyes of 18 (45%) kittens were managed medically. Surgery was performed under general anesthesia/sedation (30 occasions) or topical anesthesia (21 occasions) on 30 (56%) eyes of 22 kittens; 12 eyes (40%) underwent multiple surgeries. Four techniques were commonly employed: separation of conjunctival-to-conjunctival adhesions ± eyelid margins (14 eyes); resection of third eyelid adhesions ± temporary tacking of the third eyelid (modified Arlt's pterygium technique; 18 eyes); en bloc resection of the third eyelid (two eyes); and separation of corneoconjunctival adhesions (14 eyes). Median duration of follow-up was 55 days (range 1-1051). Median symblepharon grade in kittens treated surgically improved for all types except corneoconjunctival symblepharon. Median symblepharon grade in kittens receiving medical management remained the same or improved. Corneoconjunctival symblepharon opacity decreased for eyes treated surgically but increased for eyes treated medically. Three eyes were enucleated due to complications of corneoconjunctival symblepharon. At final presentation, symblepharon persisted in 46 (85%) eyes; however, menace response was evident in 13/16 eyes and dazzle reflex in 23/23 eyes. CONCLUSIONS AND RELEVANCE: Symblepharon is a heterogeneous group of conditions with diverse anatomic involvement, clinical appearance and impact, optimal treatment and prognosis for vision.
