Co-pyrolysis of neem wood bark and low-density polyethylene: influence of plastic on pyrolysis product distribution and bio-oil characterization.

In this study, the investigation on the effect of plastic during co-pyrolysis with biomass was carried out in a fixed reactor. Pyrolysis of neem wood bark (NB), low density polyethylene (LDPE) and their blends at different ratios was performed in order to evaluate the product distribution. The effects of reaction temperature and NB-to-LDPE blend ratio on product distribution and the chemical compositions of pyrolysis oil were examined. The co-pyrolysis of NB and LDPE increased the yield and quality of the bio-oil. The experiments were conducted under different LDPE addition percentages such as 20%, 40%, 50%, 60% and 80%. Under the optimum experimental condition of 60% addition of LDPE and a temperature of 450 °C, the maximum yield of bio-oil (64.8 wt%) and hydrocarbon (75.2%) was achieved with the lowest yield of oxygenated compounds. The calorific value of the co-pyrolysis oil was found to be higher than that of the NB pyrolysis oil. The relationship between NB and LDPE during co-pyrolysis was validated with the help of gas chromatography-mass spectrometry (GC-MS) analysis, which showed decreased oxygenated compounds.

An integrated CRITIC-TOPSIS- and Entropy-TOPSIS-based informative weighting and ranking approach for evaluating green energy sources and its experimental analysis on pyrolysis.

Selection of the most suitable biomass material for bio-fuel generation is a complex and multi-criteria decision problem as it engages many conflicting criteria which have to be assessed simultaneously. In the past, researchers have used subjective weighing techniques, which question the reliability of the approach. In this study, two objective weighing methods such as Criteria Importance Through Intercriteria Correlation (CRITIC) and Entropy are used to calculate the weights of evaluating criteria and Technique for Order of Preference by Similarity to an Ideal Solution (TOPSIS) is applied to select the suitable biomass material. This study considered six biomass alternatives such as lemongrass (A1), hard wood (A2), rice husk (A3), wheat straw (A4), rice straw (A5), and switch grass (A6), and seven important criteria such as volatile matter, fixed carbon, moisture and ash content, lignin, cellulose, and hemicellulose have been evaluated. Both the approaches show that switch grass has been the best alternative for yielding more bio-oil while rice straw is seen as the worst preferred option among the selected biomass materials. These approaches are systematic having simple computational procedure for determination of complete ranking of biomass materials. At the end of the study, the prediction is also validated by conducting pyrolysis experiments and characterization study. The experimental findings are identical and indicating a strong correlation between MCDM approach and real-time study.

Incidence and predictors of atrial septal defect after percutaneous transvenous mitral commissurotomy - a transesophageal echocardiographic study of 209 cases.

BACKGROUND: The incidence of atrial septal defect (ASD) after percutaneous transvenous mitral commissurotomy (PTMC) ranges from 15.2% to 92% in small studies. AIM: To estimate the incidence of atrial septal defect (ASD) following PTMC and to determine the factors contributing to its development. METHODS: We studied 209 patients with mitral stenosis (MS) undergoing PTMC. Transesophageal echocardiography (TEE) with color Doppler examination was performed to detect ASD. RESULTS: TEE demonstrated ASD in 139 (66.5%) of 209 patients. The mean diameter of the interatrial septal defect detected by TEE was 4.47 ± 1.7 mm. The most common site of septal puncture was the inferior vena caval side of the interatrial septum followed by fossa ovalis. Color flow imaging across the defect showed left to right shunting in all the patients (100%). We examined the relationship of age, Wilkins score, left atrial volumes, the mitral valve orifice area, mitral valve gradient, and the degree of mitral and tricuspid regurgitation between the group that developed ASD and the group without ASD and found that none of these factors predicted the development of ASD. A residual ASD was seen in 11 patients (8.7%) at 6-month follow-up. CONCLUSION: Incidence of residual atrial septal defect immediately following PTMC by TEE color flow Doppler imaging is 66.5%. Surrogate markers of elevated left atrial pressures do not determine the development of atrial septal defect after PTMC. The majority of the defects close spontaneously and a residual defect is observed in 8.7% patients at 6 months.

Incidence and predictors of left atrial thrombus in patients with rheumatic mitral stenosis and sinus rhythm: a transesophageal echocardiographic study.

BACKGROUND: Rheumatic mitral stenosis (MS) predisposes to left atrial (LA) thrombus formation. The reported incidence of LA clot formation in sinus rhythm (SR) is 2.4-13.5% in small studies. AIM: To determine the incidence of LA thrombus in MS in SR in a large cohort of patients and to determine the factors that predict its development. METHODS: Total of 848 consecutive patients with MS in SR who were being evaluated for percutaneous transvenous mitral commisurotomy were included in the study. Both transthoracic (TTE) and transesophageal echocardiograms (TEE) were performed to identify clot and other hemodynamic parameters. RESULTS: The mean age of the study population was 34 ± 9 years and the mean mitral orifice area was 0.78 ± 0.18 cm(2). Out of 848 patients 56 (6.6%) had LA thrombus on TEE. On univariate analysis there was a trend toward thrombus formation in individuals with age >44 years, LA inferosuperior dimension >6.9 cm, mean mitral gradient >18 mmHg and dense spontaneous echo contrast (SEC). On multivariate analysis none of the factors predicted clot formation. CONCLUSION: The incidence of LA thrombus in MS in SR is 6.6%. TEE is warranted in MS patients in SR when they are >44 years, LA inferosuperior dimension >6.9 cm and mean mitral gradient >18 mmHg. When SEC is absent on TEE, thrombus formation is unlikely.