Integrated fuel cell system for sustainable wastewater treatment, ammonia recovery, and power production.

The industrial production of synthetic fertilizers and the wide-scale combustion of fossil fuels have disrupted the global nitrogen cycle, necessitating a prudent shift towards sustainable nitrogen management. Traditional wastewater treatment methods primarily focus on nitrogen elimination rather than recovery in useable form, exacerbating resource depletion and environmental degradation. This review explores integrated technologies, including bio-electroconcentration cells (BEC), direct ammonia fuel cells (DAFC), solid oxide fuel cells (SOFC), and microbial fuel cells (MFC), for effective nutrient recovery in conjugation with energy recovery. Recovered nitrogen, primarily green ammonia, offers a carbon-free energy carrier for diverse applications, including applications in DAFC and SOFC. This review underscores the importance of synchronously retrieving ammonia from wastewater and efficiently diverting it for energy recovery using an integrated fuel cell approach. The key technical challenges and future perspectives are discussed, highlighting the potential of these integrated systems to advance sustainability and circular economy goals.

Graphene and biochar-based cathode catalysts for microbial fuel cell: Performance evaluation, economic comparison, environmental and future perspectives.

Microbial fuel cells (MFCs) have been the prime focus of research in recent years because of their distinctive feature of concomitantly treating and producing electricity from wastewater. Nevertheless, the electrical performance of MFCs is hindered by a protracted oxygen reduction reaction (ORR), and often a catalyst is required to boost the cathodic reactions. Conventional transition metals-based catalysts are expensive and infeasible for field-scale usage. In this regard, carbon-based electrocatalysts like waste-derived biochar and graphene are used to enhance the commercialisation prospects of MFC technology. These carbon-catalysts possess unique properties like superior electrocatalytic activity, higher surface area, and high porosity conducive to ORR. Theoretically, graphene-based cathode catalysts yield superior results than a biochar-derived catalyst, though at a higher cost. In contrast, the synthesis of waste-extracted biochar is economical; however, its ability to catalyse ORR is debatable. Therefore, this review aims to make a side-by-side techno-economic assessment of biochar and graphene-based cathode catalyst used in MFC to predict the relative performance and typical cost of power recovery. Additionally, the life cycle analysis of the graphene and biochar-based materials has been briefly discussed to comprehend the associated environmental impacts and overall sustainability of these carbo-catalysts.

Microbial fuel cell coupled Fenton oxidation for the cathodic degradation of emerging contaminants from wastewater: Applications and challenges.

Urbanization and industrialization have resulted in the escalation of the occurrence of emerging contaminants (EC) in the wastewater and ultimately to the receiving water bodies due to their bio-refractory nature. The presence of ECs in the water bodies adversely affects all three domains of life, viz. bacteria, archaea and eukaryotes, and eventually the ecosystem. Fenton oxidation is one of the most suitable method that is capable of degrading a variety of ECs by employing a strong oxidizing agent in the form of •OH. The coupling of Fenton oxidation with microbial fuel cell (MFC) offers benefits, such as low-cost, minimal requirement of external energy, and in-situ generation of oxidizing agents. The resulting system, termed as bio-electro-Fenton MFC (BEF-MFC), is capable of degrading the ECs in the cathodic chamber, while harvesting bioelectricity and simultaneously removing oxidizable organic matter from wastewater in the anodic chamber. This review discusses the applications of BEF-MFC for the treatment of dyes, pharmaceuticals, pesticides, and real complex wastewaters. Additionally, the effect of operating conditions on the performance of BEF-MFC are elaborated and emphasis is also given on possible future direction of research that can be adopted in BEF-MFC in the purview of up-scaling.

Waste-derived iron catalyzed bio-electro-Fenton process for the cathodic degradation of surfactants.

The application of waste-derived iron for reuse in wastewater treatment is an effective way of utilizing waste and attaining sustainability in the overall process. In the present investigation, bio-electro-Fenton process was initiated for the cathodic degradation of surfactants using waste-iron catalyzed MFC (WFe-MFC). The waste-iron was derived from spent tonner ink using calcination at 600 °C. Three surfactants namely, sodium dodecyl sulphate (SDS), cetyltrimethylammonium bromide, and Triton x-100 were selected as target pollutants. The effect of experimental factors like application of catalyst, contact time, external resistance, and anodic substrate concentration on the SDS degradation was investigated. At a neutral pH, the cathodic surfactants removal efficiency in WFe-MFC was above 85% in a contact time of 180 min with the initial surfactant concentration of ∼20 mg L-1 and external resistance of 100 Ω. The long-term operation using secondary treated real wastewater with unchanged cathode proved that the catalyst was still active to produce effluent SDS concentration of less than 1 mg L-1 in 4 h of contact time after 16 cycles. In a way, the present investigation suggests a potential application for spent tonner ink in the form of Fenton catalyst for wastewater treatment via bio-electro-Fenton MFC.

Cyclic di-GMP acts as a cell cycle oscillator to drive chromosome replication.

Fundamental to all living organisms is the capacity to coordinate cell division and cell differentiation to generate appropriate numbers of specialized cells. Whereas eukaryotes use cyclins and cyclin-dependent kinases to balance division with cell fate decisions, equivalent regulatory systems have not been described in bacteria. Moreover, the mechanisms used by bacteria to tune division in line with developmental programs are poorly understood. Here we show that Caulobacter crescentus, a bacterium with an asymmetric division cycle, uses oscillating levels of the second messenger cyclic diguanylate (c-di-GMP) to drive its cell cycle. We demonstrate that c-di-GMP directly binds to the essential cell cycle kinase CckA to inhibit kinase activity and stimulate phosphatase activity. An upshift of c-di-GMP during the G1-S transition switches CckA from the kinase to the phosphatase mode, thereby allowing replication initiation and cell cycle progression. Finally, we show that during division, c-di-GMP imposes spatial control on CckA to install the replication asymmetry of future daughter cells. These studies reveal c-di-GMP to be a cyclin-like molecule in bacteria that coordinates chromosome replication with cell morphogenesis in Caulobacter. The observation that c-di-GMP-mediated control is conserved in the plant pathogen Agrobacterium tumefaciens suggests a general mechanism through which this global regulator of bacterial virulence and persistence coordinates behaviour and cell proliferation.

Surfactant removal from wastewater using photo-cathode microbial fuel cell and laterite-based hybrid treatment system.

Sodium dodecyl sulfate (SDS) is a widely used anionic surfactant, which finds its way to the receiving water body due to the incapability of conventional wastewater treatment systems to completely remove it. A hybrid treatment system consisting of upflow microbial fuel cell (MFC) with titanium dioxide (TiO2) as a photocathode catalyst was developed for treating synthetic wastewater spiked with SDS (10.00 ± 0.46 mg L-1). Effluent from anodic chamber of MFC was passed through raw laterite soil filter followed by the photo-cathodic chamber with TiO2-coated cathode irradiated with the UV spectrum. This hybrid system was operated under varying hydraulic retention time (HRT) in anodic chamber of MFC. The SDS removal efficiency of more than 96% along with organic matter removal efficiency of more than 71% was obtained by this hybrid system at different HRTs. The MFC having cathode coated with TiO2 could generate a maximum power density of 0.73 W m-3 and 0.46 W m-3 at the HRT of 12 h and 8 h, respectively, showing the adverse effect of increased SDS loading rate on the electrical performance of MFC. This investigation highlighted the importance of HRT in anodic chamber of MFC and offered solution for effective removal of surfactant from wastewater.

A novel bio-electro-Fenton process for eliminating sodium dodecyl sulphate from wastewater using dual chamber microbial fuel cell.

The frequent occurrence of surfactants in urban wastewaters represents a multifaceted environmental concern. In this investigation, bio-electro-Fenton-microbial fuel cell (BEF-MFC) was developed for the degradation of sodium dodecyl sulphate (SDS) from wastewater. The synthesised cathode catalyst (powdered activated carbon and iron oxide) facilitated the Fenton reaction in the cathodic chamber of the MFC, concurrently generating a maximum power density of 105.67 mW m-2. The overall performance of the BEF-MFC for SDS removal and power generation excelled the control MFC (C-MFC) having carbon black coated cathode under similar operating conditions. Although, the rate of SDS degradation was favourable in acidic pH, under neutral pH, 70.8 ± 6.4% of SDS degradation was achieved in 120 min in BEF-MFC. A comparison of environmental impacts of BEF-MFC with up-flow MFC and electrochemical oxidation using life cycle assessment tool suggests that BEF-MFC can be one of the promising technologies for the tertiary treatment of wastewater.

A solution to the accelerated-predator-satiety Lotka-Volterra predator-prey problem using Boubaker polynomial expansion scheme.

In this study, an analytical method is introduced for the identification of predator-prey populations time-dependent evolution in a Lotka-Volterra predator-prey model which takes into account the concept of accelerated-predator-satiety. Oppositely to most of the predator-prey problem models, the actual model does not suppose that the predation is strictly proportional to the prey density. In reference to some recent experimental results and particularly to the conclusions of May (1973) about predators which are 'never not hungry', an accelerated satiety function is matched with the initial conventional equations. Solutions are plotted and compared to some relevant ones. The obtained trends are in good agreement with many standard Lotka-Volterra solutions except for the asymptotic behaviour.

Waste-derived biochar: Applications and future perspective in microbial fuel cells.

Application of microbial fuel cell (MFC) is coming to the forefront as a dual-purpose system for wastewater treatment and energy recovery. Future research should emphasize on developing low-cost field-scale MFCs for removal of organic matter, nutrients, xenobiotic and recalcitrant compounds from wastewaters and powering low energy devices. For achieving this, low-cost electrodes, low-cost yet efficient cathode catalysts and proton exchange membrane (PEM) should be developed from waste-based resources to salvage the waste-derived material as much as possible, thereby reducing the fabrication cost of this device. Biochar is one such low-cost material, which has wide range of applications. This review discusses different applications of biochar in MFC, viz. in the form of standalone electrodes, electrocatalyst and material for PEM in light of different characteristics of biochar. Further emphasis is given on the future direction of research for implementation of biochar-based PEMs and electrodes in field-scale MFCs.

Estimation of time since death from CSF electrolyte concentration in Bhopal region of central India.

Estimation of time since death from sodium and potassium ion concentration levels in CSF (cerebrospinal fluid) was carried out in 100 medico legal autopsies with known time of death in the department of Forensic medicine, Gandhi Medical College in Bhopal region of Central India. CSF was aspirated from lateral ventricles after opening the skull and dura, and concentration of these ions were estimated by flame photometry. Results revealed a significant correlation of sodium and potassium ions in CSF up to 25 h of time since death, with average per hour rise of 1.21 meq/h for potassium and fall of 1.115 meq/h for sodium ions. A useful relationship between sodium potassium ion ratio and PMI (post-mortem interval) was also elicited. The study concludes that changes in CSF electrolyte is a significant parameter to estimate time since death.

Spontaneous ignition in case of celphos poisoning.

Celphos (aluminum phosphide) poisoning is the most common cause of poisoning in India. The mechanism of action, acute and chronic effect on human body, its symptoms and signs, and the line of treatment are well documented and research is still going on to find a suitable antidote. "Spontaneous ignition" is a rare but interesting finding in case of aluminum phosphide poisoning. We present the autopsy findings in this case report along with the probable factors that led to occurrence of such finding.

4. Cerebral venous thrombosis in pregnancy: a case report.

Sudden unexpected death in many instances comes with stimulating or interesting findings, often in contrast to the history provided. Two cases of sudden death in pregnant females with central venous thrombosis are described, because of their rarity. The incidence, etiological factors, predisposing conditions and the ethical and legal questions arising from such deaths are discussed.

Pulmonary homograft: should it be used in the aortic position?

OBJECTIVE: Retrospective analysis was performed to determine the suitability of pulmonary homograft as an aortic valve substitute. METHODS: From January 1994 through June 1999, 147 patients (mean age, 32.2 +/- 17.3 years) underwent aortic valve replacement with either an aortic homograft (group 1: n = 103, 25 fresh antibiotic preserved and 78 cryopreserved) or a pulmonary homograft (group 2: n = 44, 11 antibiotic preserved and 33 cryopreserved). In group 1 a scalloped subcoronary technique was used in 64 patients, and a root replacement technique was used in 39 patients. In group 2 the scalloped subcoronary technique was used in 34 patients, and the root replacement technique was used in 10 patients. RESULTS: There were 131 operative survivors (group 1 = 91; group 2 = 40). Follow-up ranged from 2 to 62 months. In group 1 none of the patients had significant aortic regurgitation during the hospital stay. Three patients (all having undergone the scalloped subcoronary technique) had moderate aortic regurgitation after 6 to 32 months. In group 2, 10 patients (9 having undergone the scalloped subcoronary technique and 1 having undergone the root replacement technique) developed significant regurgitation: 2 intraoperatively, 5 in the early postoperative period before discharge from the hospital, and 3 during late follow-up 6 to 12 months postoperatively. Among the various risk factors analyzed for overall homograft failure, use of a pulmonary homograft was the single independent predictor of valve failure (odds ratio, 8.6; 95% confidence interval, 1.9-39; P =.006). CONCLUSION: Pulmonary homograft, when inserted by means of a scalloped subcoronary technique, is not a suitable aortic valve substitute.

Lyophilized aqueous based polymer matrices for transdermal delivery of captopril.

Transdermal system(s) bearing captopril were developed using a low temperature casting method and aqueous based polymers viz., eudragit RL-100 and polyvinyl pyrrolidone (PVP). The developed system(s) were subjected to an in vitro characterization study. The results were compared with the transdermal systems of the same composition prepared at room temperature. The study revealed that the system(s) prepared using the low temperature casting method performed better in comparison to those prepared at room temperature. The developed system(s) followed zero order release kinetics.

Efficacy of aprotinin, epsilon aminocaproic acid, or combination in cyanotic heart disease.

BACKGROUND: Aprotinin and epsilon aminocaproic acid are antifibrinolytic agents used to reduce postoperative blood loss after cardiopulmonary bypass. We compared low dose aprotinin with epsilon aminocaproic acid and a combination of the two agents to reduce postoperative blood loss in infants with congenital cyanotic heart disease undergoing corrective surgical procedures. METHODS: This prospective study was conducted randomly on 300 children. Group I (n = 80) acted as the control and did not receive either of the study drugs. Group II (n = 100) received low dose aprotinin, group III (n = 60) received epsilon aminocaproic acid, and group IV (n = 60) received a combination of the two antifibrinolytic agents. RESULTS: The control group had the longest time for sternal closure, maximum blood loss at 24 hours, and greatest requirements for packed red blood cells and platelets. Fibrinogen levels were significantly lower, and levels of fibrin breakdown products were significantly higher compared with the groups given either or both of the antifibrinolytics. CONCLUSIONS: Epsilon aminocaproic acid is as efficacious as low dose aprotinin in reducing postoperative blood loss and packed red blood cell and platelet requirements in children with congenital cyanotic heart disease. The combination of the two was slightly more effective.

Fibrinolytic activity in bleeding associated with intrauterine contraceptive devices.

A prospective study was conducted to assess endometrial fibrinolytic activity before and after insertion of copper 250 (Multiload) and after removal of the IUCD. Fibrinolytic activity was measured on the fibrin plate in the form of zone of lysis. Sixty two women in the control group had fibrinolytic activity of endometrium in the range of 0.3-9.5 cm2 (mean +/- SD 1.77 +/- 1.27), 40 women who wanted to have the IUCD removed, because of reasons other than bleeding had a range of 0-9.5 cm2 (mean +/- SD 2.28 +/- 1.88) while 48 women who had the IUCD removed because of subjective menorrhagia had a range of 2.24-7.56 cm2 (mean +/- SD 4.75 +/- 1.20) which was higher than in the other two groups.

PIP: During 1987-1988, physicians followed 150 endometrial biopsy patients at the Institute of Medical Sciences of Banaras Hindu University in Varanasi, India, who used the copper 250 IUD (Multiload) to examine fibrinolytic activity of the endometrium. They divided the women into 3 groups: group I--62 women seeking an IUD and who had no menstrual complaints (control group); group II--40 women wanting the IUD removed for reasons other than bleeding; group III-48 women wanting the IUD removed for menorrhagia. A fibrin plate in the form of Zone of lysis was used to measure fibrinolytic activity. The area of lysis in the control group varied from 0.3-9.5 sq. cm, with the 1.1-2 sq. cm area of lysis being the most common area (37%), followed by 2.1-3 sq. cm (29%) and 0-1 sq. cm (25.8%). Group II women experienced more fibrinolytic activity than the control group (mean 1.77 sq. cm vs. 2.28 sq. cm), but the difference was insignificant. On the other hand, fibrinolytic activity was significantly higher in group III (mean 4.75 sq. cm, range 2.24-7.56 sq. cm) than in groups I and II (p .001). The most common area of lysis in group III was 5.1.6 sq. cm (33.3%), followed by 3.1-4 sq. cm and 4.1-5 sq. cm, each amounting to 25%. The 2.5 times higher fibrinolytic activity in women experiencing menorrhagia demonstrated that excess bleeding is closely linked to endometrial hyperfibrinolysis brought about by insertion of an IUD. This finding motivated the physicians to suggest administration of antifibrinolytic drugs to IUD users beginning with the first cycles to reduce IUD discontinuation.

Recurrent pseudoaneurysm of the left ventricle with subcutaneous herniation into the chest wall. A case report.

Pseudoaneurysm of the left ventricle is rare, and recurrence is extremely rare. We report the case of a 62-year-old man who presented at our hospital with a painless pulsatile swelling in the left breast. He had undergone coronary artery bypass grafting and left-ventricular aneurysmectomy 14 years earlier. On investigation, the swelling was diagnosed to be a pseudoaneurysm of the left ventricle with subcutaneous herniation. The extreme rarity of this condition prompted us to report the case. The investigative techniques and the surgical strategy are discussed.

Mitral valve repair in a predominantly rheumatic population. Long-term results.

Valve repair in rheumatic patients poses special problems due to valve deformity and mixed lesions. We present our experience from January 1988 through June 1999, in this retrospective study of 818 patients (377 males). The mean age was 22.8 +/- 11.3 years (range, 2 to 70 years). The cause of mitral regurgitation was rheumatic in 718 (88%) patients, congenital in 51, myxomatous in 34, infective in 7, and ischemic in 8. Most patients (64%) were in New York Heart Association functional class III or IV. Congestive heart failure was present in 116 patients (14%). Reparative procedures included posterior collar annuloplasty (n=710), commissurotomy (n=482), cusp-level chordal shortening (n=237), cusp thinning (n=222), cleft suture (n= 166), and cusp excision/plication (n=42). Operative mortality was 4% (32 patients). Preoperative left ventricular dysfunction, presence of congestive heart failure, and advanced functional class were associated with greater mortality. Follow-up ranged from 1 to 144 months (mean, 44.9 +/- 33.2 months) and was 96% complete. Most survivors (70%) had no or trivial mitral regurgitation. Forty patients required reoperation for valve dysfunction. There were 23 (2.8%) late deaths. Actuarial, reoperation-free, and event-free survival at 11 years were 92.6% +/- 1.0%, 65.0% +/- 10%, and 38% +/- 6.0%, respectively Among the survivors, 85% were in New York Heart Association functional class I. We conclude that mitral valve repair in rheumatic patients, using current techniques, can effectively correct hemodynamic and functional abnormalities with satisfactory results.

Molecular flexibility of Mycobacterium tuberculosis ribosome recycling factor and its functional consequences: an exploration involving mutants.

Internal mobility of the two domain molecule of ribosome recycling factor (RRF) is known to be important for its action. Mycobacterium tuberculosis RRF does not complement E. coli for its deficiency of RRF (in the presence of E. coli EF-G alone). Crystal structure had revealed higher rigidity of the M. tuberculosis RRF due to the presence of additional salt bridges between domains. Two inter-domain salt bridges and one between the linker region and the domain containing C-terminal residues were disrupted by appropriate mutations. Except for a C-terminal deletion mutant, all mutants showed RRF activity in E. coli when M. tuberculosis EF-G was also co-expressed. The crystal structures of the point mutants, that of the C-terminal deletion mutant and that of the protein grown in the presence of a detergent, were determined. The increased mobility resulting from the disruption of the salt bridge involving the hinge region allows the appropriate mutant to weakly complement E. coli for its deficiency of RRF even in the absence of simultaneous expression of the mycobacterial EF-G. The loss of activity of the C-terminal deletion mutant appears to be partly due to the rigidification of the molecule consequent to changes in the hinge region.