Investigation of performance of potential adsorbents for emissions mitigation in a diesel generator.

Globally, the release of greenhouse gases primarily carbon dioxide (CO2) emissions to our Earth's surface has climbed by  about 45% to its present atmospheric concentration rate of 420 parts per million (ppm) during the industrial era. An unprecedented rise in atmospheric CO2 concentration has been claimed to lead to significant factors such as global warming potential (GWP) and climate change effects.  An increase in atmospheric CO2 concentrations is  a  serious threat to the environment. Recent research efforts have focused on mitigating emissions from anthropogenic point sources. Adsorption-based post-combustion CO2 capture using solid adsorbents is the most effective and efficient method for mitigating gas adsorption in the exhaust system. In the current study, activated carbons are obtained from three potential biomass, namely, (i) coconut shell, (ii) rice husk, and (iii) eucalyptus wood, through a - single-stage activation method. The prepared activated carbon materials are analyzed using proximate and ultimate analyses. Further investigations are performed using different characterization techniques to ensure their adsorption efficiency. Adsorbents are packed one after the other in an in-house fabricated double adsorption chamber and coupled to the exhaust unit of a generator. Test experiments are conducted to examine adsorbents' capture efficiency in emissions mitigation. Adsorbents' adsorption parameters are evaluated in experimental investigations. At 2.5 bar and 50 °C, a maximum loading capacity of samples is achieved by 4.85 mmol/g, 4.58 mmol/g, and 5.96 mmol/g for coconut shell, rice husk, and eucalyptus wood adsorbents, respectively. With a post-combustion carbon adsorption chamber, CO2 and NO are captured about 40-64% and 38-58%, respectively, for all three adsorbents. The thermodynamic parameter of isosteric heat of adsorption value is below 40 kJ/mol, ensuring physisorption for all adsorbents.

Multiobjective optimization of membrane in hybrid cryogenic CO2 separation process for coal-fired power plants.

Post-combustion carbon dioxide (CO2) capture is considered a potential method to mitigate CO2 emissions from fossil fuels burned in power plants. In recent years, combining two different methods of post-combustion CO2 capture such as membrane and cryogenic distillation has been explored for availing the advantages of each method. This study focuses on the optimization of membranes for developing the membrane-cryogenic distillation process. For this purpose, a process flow sheet is developed, and simulation with model components such as compressor, heat exchanger, turbo expander, and distillation column is carried out using Aspen Plus. A membrane model is developed using in-house MATLAB code, and optimization is done to achieve higher concentration and recovery of CO2 using the MOJAYA algorithm. The membrane model is coupled to Aspen Plus through component object model (COM) technology. In this investigation, a hollow fiber membrane is considered. The optimized specifications of membrane modules are length, number of hollow fibers, feed pressure, and permeate pressure which are 0.3 m, 100,000, 5.76 bar, and 0.1 bar, respectively. This analysis results in the purity and recovery of the process of 99.8 and 90%, respectively, and an energy penalty of around 1.74 MJ/kg of CO2. A comparison of other processes available in the literature reveals that the current study renders maximum purity and recovery with a minimum energy penalty.

Assessment of energy, exergy, environmental, and economic study of an evacuated tube solar dryer for drying Krishna Tulsi.

In the present work, experimental studies of drying Krishna tulsi leaves in an in-house fabricated evacuated tube solar collector (ETSC) connected with an indirect solar dryer are carried out. The acquired findings are compared to those obtained from drying the leaves in open sun drying (OSD). The developed dryer takes 8 h to dry Krishna tulsi leaves; it takes 22 h in the OSD to reach a final moisture content of 12% (db) from an initial moisture content of 47.26% (db). The collector and dryer efficiencies range from 42 to 75%, 0-18%, respectively, with an average solar radiation of 720 ± 20 W/m2. The ETSC and drying chamber exergy inflow and outflow vary from 200 to 1400 W, 0 to 60 W, and from 0 to 50 W,  0 to 14 W, respectively. The ETSC and cabinet exergetic efficiencies range from 0.6-4% and 2-85%, respectively. The exergetic loss of the overall drying process is estimated to be 0-40%. The drying system sustainability indices, including improvement potential (IP), sustainability index (SI), and waste exergy ratio (WER), are calculated and presented. The value of the embodied energy of the fabricated dryer is 349.874 kWh. For an expected life span of 20 years, the dryer will reduce CO2 by 13.2 tonnes and earn carbon credits worth between 10,894 and 43,576 INR. The proposed dryer has a payback period of 0.4 years.

The role of natriuretic peptides in volume assessment and mortality prediction in Haemodialysis patients.

BACKGROUND: Maintaining optimal fluid balance is essential in haemodialysis (HD) patients but clinical evaluation remains problematic. Other technologies such as bioimpedance are emerging as valuable adjuncts. This study was undertaken to explore the potential utility of the natriuretic peptides - atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) in the assessment of fluid status and cardiovascular risk in this setting. METHODS: This was a cross-sectional study carried out in an unselected cohort of 170 prevalent HD patients. Volume status was assessed by clinical parameters - the presence or absence of peripheral oedema, raised jugular venous pressure and basal lung crepitations; by extracellular fluid volume (ECFV) status determined by whole body bioimpedance; and by serum levels of BNP and ANP (pre- and post -dialysis). The relationships of ANP and BNP levels to clinical and bioimpedance parameters of volume status was determined. Patients were followed up for 5 years to assess the relationship of natriuretic peptide levels to mortality. RESULTS: Bioimpedance estimates of ECFV expansion (>105 % of ideal ECFV) was present in 52 % of patients pre-dialysis. A significant proportion (21 %) of pre-dialysis patients had a depleted ECFV (<95 % of ideal ECFV) pre-dialysis. The situation was reversed post-dialysis. A raised JVP >3 cm was the most reliable clinical sign of ECFV expansion inferred from bioimpedance measurements and natriuretic peptide levels. The vast majority of patients with this sign also had lung crepitations or peripheral oedema or both. BNP was a stronger predictor of ECFV expansion than either pre- or post-dialysis ANP. BNP was also a stronger predictor of five-year survival. CONCLUSION: Serum levels of BNP have a strong relationship to both volume status and survival in HD patients. We found no clear role for measurement of ANP, though changes in blood levels may be a sensitive indicator of acute changes in volume status. Whether monitoring levels of these peptides has a role in the management of volume status and cardiovascular risk requires further study.

Predictors of renal and patient outcomes in anti-GBM disease: clinicopathologic analysis of a two-centre cohort.

BACKGROUND: Patients with anti-glomerular basement membrane (GBM) disease are at increased risk of morbidity and mortality from renal failure, pulmonary haemorrhage or complications of treatment. One-third also have circulating anti-neutrophil cytoplasmic antibodies (ANCA). The aim of this study was to determine the clinicopathologic predictors of patient and renal outcomes in anti-GBM disease with or without ANCA. METHODS: Retrospective review of 43 patients diagnosed with anti-GBM disease over 20 years in two centres, including nine with dual anti-GBM and ANCA positivity. Renal biopsies from 27 patients were scored for the presence of active and chronic lesions. RESULTS: Dual-positive patients were almost 20 years older than those with anti-GBM positivity alone (P = 0.003). The overall 1-year patient and renal survivals were 88 and 16%, respectively. Oligoanuria at diagnosis was the strongest predictor of mortality; none of the 16 patients without oligoanuria died. In a Cox regression model excluding oligoanuria, age was the only other independent predictor of survival. Pulmonary haemorrhage and dialysis dependence did not influence mortality. Thirty-five of the forty-three (81%) patients required dialysis at presentation, including all nine dual-positive patients. Of them, only two (5.7%) regained renal function at 1 year. By logistic regression, oligoanuria at diagnosis and percentage of crescents were independent predictors of dialysis independence at 3 months. However, in biopsied patients, the presence of crescents (>75%) added little to the presence of oligoanuria in predicting dialysis independence. Histological activity and chronicity indices did not predict renal outcome. Two of the nine (22%) dual-positive patients relapsed compared with none of the anti-GBM alone patients. Seven patients received kidney transplants without disease recurrence. CONCLUSIONS: Oligoanuria is the strongest predictor of patient and renal survival while percentage of glomerular crescents is the only pathologic parameter associated with poor renal outcome in anti-GBM disease. Kidney biopsy may not be necessary in oligoanuric patients without pulmonary haemorrhage.

Obstructive sleep apnea in incremental hemodialysis: determinants, consequences, and impact on survival.

Sleep disorders are common in hemodialysis patients, although causes and consequences remain unclear. We sought to establish prevalence, determinants, and outcomes of sleep disturbances in patients receiving incremental dialysis. One hundred two unselected patients undergoing incremental high-flux hemodialysis or hemodiafiltration underwent limited overnight sleep study. Large subsets underwent echocardiography, interdialytic ambulatory blood pressure monitoring, and brain natriuretic peptide measurements. Patients were followed up to 44 months. Full sleep data were obtained in 91 patients. All had sleep disturbance as evidenced by an apnea-hypopnea index >5/min. We defined major obstructive sleep apnea (MOSA) as an apnea-hypopnea index ≥ 15, together with either significant oxygen desaturation or symptoms of daytime sleepiness. Forty patients met these criteria. Significant independent predictors of MOSA were age <65 years, male gender, has diabetes, and has a brain natriuretic peptide >2500 pg/mL. Mean ambulatory blood pressure and left ventricular mass index were significantly higher in these patients. In a model controlling for body mass index, high C-reactive protein, and the presence of cancer, MOSA was associated with a twofold increased risk of mortality, although this did not reach statistical significance. MOSA was common, and was associated with hypertension and high left ventricular mass index. Whether obstructive sleep apnea contributes to the high mortality remains to be firmly established.

Dalteparin dosing in high-flux haemodialysis and haemodiafiltration.

BACKGROUND: Low-molecular-weight heparins are being increasingly used as an alternative to unfractionated heparin for anticoagulation of the haemodialysis (HD) circuit. Data on dalteparin use in high-flux HD and haemodiafiltration (HDF) are limited. We examined the safety and efficacy of dalteparin in this setting to enable recommendations on the optimal dose range. METHODS: This prospective study was conducted in a single dialysis unit. Subjects who had been receiving dalteparin for at least 10 HD sessions were studied. Anti-Xa activity was measured for all subjects at the start of the HD session, at 60 min into HD and at the end of dialysis. RESULTS: 55 subjects were studied. None had detectable anti-Xa activity at the start of the session. Using adequacy criteria based on target anti-Xa activity >0.4 IU/ml at 1 h and <0.4 IU/ml at the end of dialysis, 39 (71%) patients had adequate anticoagulation, 12 (22%) patients were under-anticoagulated and 4 (7%) were over-anticoagulated. The mean dose in the adequately anticoagulated group was 60.7 ± 11.7 IU/kg, in the under-anticoagulated group 39.3 ± 9.6 IU/kg and in the over-anticoagulated group 70.1 ± 14.6 IU/kg. The optimal dose of dalteparin appears to be 60 ± 10 IU/kg, which facilitates the achievement of the target anti-Xa activity in the range of 0.4-0.75 IU/ml at 1 h and <0.4 IU/ml at the session end. CONCLUSION: Dalteparin is a safe and effective anticoagulant for patients on high-flux HD and HDF. The optimal dose appears to be 60 ± 10 IU/kg. The desirable target range of anti-Xa activity is 0.4-0.75 at 1 h and <0.4 IU/ml at the session end.

Resveratrol interferes with N-nitrosodiethylamine-induced hepatocellular carcinoma at early and advanced stages in male Wistar rats.

Resveratrol, a phytochemical compound abundant in red wine and grapes, is known to affect cancer cells both in vitro and in vivo. A great amount of data have indicated the therapeutic benefits of resveratrol against cancer. However, it remains unclear whether these benefits are similar and equally effective in both the early and advanced stages of cancer or carcinogenesis. In this study, we report the effects of resveratrol in the early and advanced stages of hepatocarcinogenesis in a model of N-nitrosodiethylamine (DEN)-induced hepatocellular carcinoma (HCC) of male Wistar rats. For the experiment, rats were divided into different groups and treated with resveratrol either from day 1 of DEN administration for 15 days (pre-HCC), or after the development of HCC, i.e., 15-16 weeks after DEN administration (post-HCC), and compared to untreated HCC-bearing rats. Biochemical analysis of α-fetoprotein, the known serum marker for HCC, and other serum and liver marker enzymes also demonstrated a decreased level upon resveratrol treatment compared to the untreated HCC-bearing rats. H&E staining of tissue sections from the liver showed alteration or transformation of liver parenchymatous tissue in DEN-induced HCC (at 15-16 weeks). Resveratrol treatment during early (on day 1 of DEN-induction) and advanced (weeks 17-18) HCC showed a marked difference in the tissue architecture compared to untreated HCC. Immunoblot analysis revealed that resveratrol intervention at both the early and advanced stages of DEN-induced HCC activated the apoptotic markers, such as PARP cleavage, caspase-3 activation, p53 up-regulation and cytochrome-c release. In addition, semiquantitative RT-PCR and immunoblot analysis demonstrated the up- and down-regulation of key apoptotic regulators, such as Bax and Bcl2, respectively, in a resveratrol treatment-dependent manner. Our results indicate that the administration of resveratrol either at the early or advanced stages of hepatocarcinogenesis is equally effective and involves the activation of the apoptotic pathway in male Wistar rats.

Comparison of B-type natriuretic peptide and NT proBNP as predictors of survival in patients on high-flux hemodialysis and hemodiafiltration.

End stage renal failure is associated with very high risk of cardiovascular disease. Serum levels of B-type natriuretic peptide (BNP) and NT proBNP reflect cardiovascular risk but it is unknown which of these peptides is a better predictor of survival in this population. BNP and NT proBNP levels and other relevant parameters were measured in 103 patients on high-flux hemodialysis (HD) and hemodiafiltration. Patients were followed for 4 years or until transplantation or death. Median BNP level was 262 pg/mL while the corresponding NT proBNP level was 362 pg/mL. Levels of these peptides were significantly lower in patients receiving hemodiafiltration than in those on high-flux HD. Only 1 of the 26 patients with normal NT proBNP died during follow-up while 3 of the 33 patients with normal BNP levels died in the same period. Both median BNP and NT proBNP levels were higher in those who died during follow-up than in those who survived 4 years. Cox Proportional Hazard models showed that both logBNP and log NT proBNP were independent predictors of survival. The area under the receiver operating characteristic curve was very similar for BNP and NT proBNP (0.779 vs. 0.781) for predicting 4-year survival. Net reclassification improvement analysis showed that adding NT proBNP to the baseline model lead to improved prediction of 4-year survival. BNP and NT proBNP levels were markedly elevated in HD patients and were highly predictive of survival. NT proBNP may have marginal advantage over BNP in predicting survival in this population.

Haemodynamic effects of food intake during haemodialysis.

BACKGROUND: There is some doubt whether food intake during haemodialysis (HD) is detrimental to haemodynamic stability. METHODS: We studied 20 stable non-diabetic HD patients during a single session. A standard meal was given 45 min into dialysis. Relative blood volume (RBV), cardiac output (CO), systemic vascular resistance (SVR) and extracellular fluid (ECF) resistance were monitored continuously. Total protein and albumin were measured. RESULTS: There was a significant reduction in RBV after food ingestion (maximum reduction 3.4 +/- 1.1%; p < 0.001). There was no significant change in ECF resistance, heart rate, CO or SVR. Mean arterial pressure was significantly different from pre-food levels 30 min after food (p = 0.04). The rate of change of total protein and albumin concentration was significantly higher immediately after food ingestion. CONCLUSIONS: Food intake during HD caused significant reductions in RBV, possibly related to fluid shifts from intestinal microcirculation to interstitium. CO and SVR remained stable perhaps because of the opposing effects of food ingestion and UF.