A Study of Detonations, DDT and Deflagrations in High Pressure Ethylene-Nitrous Oxide Mixtures

Nitrous oxide (N2O) has gained popularity as a unique oxidizer due to its ability to decompose exothermically, producing nitrogen and oxygen. Additionally, there are concerns about the safety of nitrous oxide in the nuclear industry where it has been observed that stored nuclear waste generates and retains large amounts of flammable gases such as hydrogen and ammonia along with nitrous oxide. These gases are at risk of explosion even in the presence of a weak ignition source which can result in detonations more violent than those initiated directly. Nitrous oxide is also finding an application in the geothermal industry where it is being tested in combination with ethylene as a stimulant mixture to fracture rock. The detonations initiated in this mixture have the ability to produced a network of fractures in the rock formation. In the rocket industry, nitrous oxide has been used for propulsion in multiple systems, but never in a detonative mode. In order to use nitrous oxide in these areas, its detonation properties in combination with a fuel require quantification. Available literature on nitrous oxide-hydrocarbon detonations is mainly restricted to initial pressures below one atm or with dilution. Therefore, detonations with nitrous oxide as the oxidizer are far from being completely characterized. In addition to this lack of general knowledge, understanding of nitrous oxide-fuel detonations at higher pressures, more typical of practical combustion systems is either extremely limited or non-existent. In the current work, the flame acceleration, deflagration-to-detonation transition (DDT), and detonation properties of a bipropellant mixture of ethylene (C2H4) and N2O are studied as a function of initial pressures. These properties are compared to those in mixtures of ethylene-oxygen (O2). These detonations are investigated in a combustion tube designed and fabricated in-house. The performances of these two mixtures are also investigated using theoretical Chapman-Jouguet detonation calculations as a basis of comparison with the measured properties. Additionally, detonation properties in a mixture of acetylene (C2H2) and nitrous oxide are also investigated to compare the two fuels. While C2H2 is a highly energetic fuel with theoretically high performance, it presents serious practical storage concerns when considered for propulsion applications. These practical issues motivates the investigation of C2H4 as a potential alternative fuel, which is relatively easy to manage. A critical requirement for the application of bipropellant mixtures to detonation systems is rapid flame acceleration to achieve significant chamber pressure rise in a short distance with the potential for a prompt transition to detonation. This DDT behavior of mixtures using N2O and O2 with C2H4and C2H4is investigated for increasing initial pressures in the experimental portion of this work. This behavior is quantified by measuring the run-up distances leading to DDT. The pre-compression of the bipropellant mixtures during flame acceleration caused by the accelerating flame is also estimated and directly measured using appropriate instrumentation. These direct measurements of pre-compression are further used to estimate the path of the accelerating flame in the combustion tube. These estimates are compared with the flame tracked by high-speed imaging in an optically accessible combustion tube

Manual small incision cataract surgery in eyes with white cataracts

PURPOSE: To assess the safety and efficacy of Manual Small Incision Cataract Surgery (MSICS) in cases of white cataract with the use of trypan blue as an adjunct for performing continuous curvilinear capsulorthexis (CCC). MATERIALS AND METHODS: Prospective observational study on 100 consecutive eyes of 100 patients with white cataract who had undergone MSICS with trypan blue assisted CCC. The nucleus was prolapsed into anterior chamber by using a sinskey hook and extracted out of the eye using irrigating vectis. Intraoperative and postoperative findings (according to OCTET classification) as well as postoperative visual outcomes were used as main measures to report the safety and efficacy of the surgery. RESULTS: Of the 100 eyes, 16 had intumescent, 67 had mature and 17 had hypermature cataract. Intraoperatively CCC was incomplete in 4 eyes (4%) and had to be converted to canopener capsulotomy. None of the eyes had posterior capsular rupture or zonular dialysis and no eyes were converted to conventional Extra Capsular Cataract Extraction (ECCE). Postoperatively, 6 eyes (6%) developed corneal oedema with >10 Descemets folds and 7 eyes (7%) had corneal oedema with < 10 Descemets folds. Mild iritis was seen in 6 eyes (6%) and moderate iritis with fibrin membrane was seen in 3 eyes (3%). Iridodialysis was observed in 1 eye (1%). Of the 99 patients (99%) categorised under good visual outcomes category, 94 patients (94%) had a best-corrected visual acuity of 6/9 or better on the 40th post-operative day. CONCLUSION: In developing countries like India where phacoemulsification may not be affordable to a majority of those requiring cataract surgery, MSICS proves to be a safe and efficacious alternative for white cataracts especially with the adjunctive use of trypan blue dye

An Altered Pulmonary Function – A Cause or Consequence of Gastro Esophageal Reflux Disease (GERD)

Objective: To evaluate the pulmonary function in Gastroesophageal reflux disease (GERD) patients without respiratory symptoms. Background: GERD is reported to adversely impact the pulmonary functions. GERD is associated with symptomatic asthma and chronic cough. Pulmonary functions are studied in symptomatic asthma patients with GERD. Treatment of GERD improves the respiratory symptoms and decreases the medication needed for the management of asthma. This study was undertaken to evaluate the pulmonary functions in GERD patients without respiratory symptoms. Methods: A cross sectional study was conducted in clinically diagnosed GERD cases (18 males and 15 females), confirmed by endoscopic examination without respiratory symptoms. Age, gender and anthropometrically matched healthy subjects served as controls. Pulmonary functions (FVC, FEV1, FEV1/FVC ratio and PEFR) were recorded using a computerized spirometer (Spirobank G) in sitting position. Percentage of predicted values was expressed as mean ± SD and was used for comparison. Results: There was a statistically significant reduction in FVC, FEV1 and PEFR in GERD patients without respiratory symptoms compared to controls (p < 0.05). Conclusion: It can be concluded that subjects suffering from GERD without respiratory symptoms also have an altered pulmonary function showing predominantly obstructive type with mild to moderate restrictive airway changes

Rhizomelic chondrodysplasia punctata: A missed opportunity for early diagnosis

A male neonate was born with rhizomelic shortening of limbs. Skeletal radiograph showed punctate calcification of epiphysis of humerus, femur, and tibia. The diagnosis and a brief review of literature pertaining to the condition with emphasis on antenatal diagnosis and counseling are being reported

Outcomes of malignancy in adults with congenital heart disease: a single center experience.

Malignancy is known to be a major cause of death in adult congenital heart disease (ACHD). However, data regarding cardiovascular and cancer-related outcomes in ACHD are lacking.We conducted a retrospective single-center cohort study comprising patients with ACHD and malignancy. The primary outcome was all-cause mortality. Key secondary outcomes included major adverse cardiovascular and cerebrovascular events (MACCE), cardiotoxicity events and consequent cancer therapy modifications.Sixty-eight patients with ACHD and a history of cancer were included in the study. 82% of patients had moderate or great ACHD anatomic complexity. Over a median follow-up of 5 years after cancer diagnosis, 16 (24%) patients died, with 69% of deaths being due to cancer. Univariate predictors of mortality were baseline arrhythmia (OR 3.82, 95% CI 1.15-12.67, p = 0.028), baseline diuretic therapy (OR 3.54, 95% CI 1.04-12.04, p = 0.044) and advanced cancer stage at diagnosis (OR 2.37, 95% CI 1.32-4.25, p = 0.004). MACCE occurred in 40 (59%) patients and was independently predicted by baseline diuretic requirement (OR 9.91, 95% CI 1.12-87.85, p = 0.039). A&nbsp;14% incidence of cardiotoxicity was seen; 3 patients needed modification and 1 patient needed temporary interruption of cancer therapy for 2 weeks.Considerable mortality occurred in this cohort of patients with ACHD and cancer; most deaths were cancer-related. A high rate of MACCE was observed, yet rates of obligatory modification of cancer therapy due to cardiotoxicity were low