Isotopic tracing of leachate percolation from municipal solid waste dump sites to groundwater in diverse climatic zones of India.

Groundwater resources in tropical regions are largely dependent on recharge by rainwater infiltration through soil layers with variable time. However, the rainwater infiltration through soil is a serious concern in urban tropics where it interacts with landfills at the dumpsites, potentially contaminating adjoining groundwater. In this study, the stable isotopic compositions of oxygen and hydrogen (δ18O and δ2H, respectively) in groundwater and leachates, adjoining municipal dumpsites in urban tropics (Bangalore, Kolkata and Durgapur located in diverse rainfall zonation of India), were analyzed to investigate their recharge sources and trace the possible mixing of leachate contaminants under three diverse climatology. The measured values of δ18O and δ2H suggested that the groundwater in these sites reflects higher recharge by rainwater. However, the d-excess values indicated secondary effects suggesting the groundwater has experienced significant modifications. The end member analysis using δ18O-d-excess relation pinpointed an additional leachate contribution from adjoining dumpsites. The critical fraction of leachate infiltration to groundwater quantified using two component mixing model ranged between (i) 1 and 33% in Bangalore, (ii) 5 and 13% in Kolkata and (iii) 18 and 76% in Durgapur, with its variability dependent on seasonality and aquifer connectivity. This information is crucial for groundwater management to secure water quality and to quantify potential hydrological contaminants particularly in drier seasons and drier regions, when and where the demand for groundwater is high, respectively.

Subjective cognitive deficits and its correlates among patients with bipolar disorder: Findings from the bipolar disorder course and outcome study from India (BiD-CoIN study).

Aim: This study aimed to evaluate the prevalence of subjective cognitive complaints and their association with clinical variables, insight, and disability. Methodology: Seven hundred and seventy-three subjects with bipolar disorder (BD), recruited across 14 centers, currently in the euthymic phase were cross-sectionally evaluated on Cognitive Complaints in Bipolar Disorder Rating Assessment (COBRA). Results: The mean total COBRA score was 9.79 (SD: 6.99), and 322 (41.7%) of the participants were found to have subjective cognitive complaints when the cut-off of >10 was used. Compared to those without cognitive complaints, those with cognitive complaints more often had depression as the first episode in their lifetime, had a higher prevalence of alcohol dependence, a higher number of depressive episodes (first five years of illness, lifetime, and per year of illness), a higher number of manic episodes in the first five years of illness, more often had depressive or indeterminate predominant polarity, lower prevalence of at least one-lifetime episode with psychotic symptoms, higher severity of residual symptoms, spent more time in the episodes in the lifetime, had poorer insight and higher disability. Conclusion: The present study suggests subjective complaints complaints are associated with more severe illness, higher levels of residual symptoms, poor insight, and higher disability.

Stretchable Sensors for Soft Robotic Grippers in Edge-Intelligent IoT Applications.

The rapid development of electronic material and sensing technology has enabled research to be conducted on liquid metal-based soft sensors. The application of soft sensors is widespread and has many applications in soft robotics, smart prosthetics, and human-machine interfaces, where these sensors can be integrated for precise and sensitive monitoring. Soft sensors can be easily integrated for soft robotic applications, where traditional sensors are incompatible with robotic applications as these types of sensors show large deformation and very flexible. These liquid-metal-based sensors have been widely used for biomedical, agricultural and underwater applications. In this research, we have designed and fabricated a novel soft sensor that yields microfluidic channel arrays embedded with liquid metal Galinstan alloy. First of all, the article presents different fabrication steps such as 3D modeling, printing, and liquid metal injection. Different sensing performances such as stretchability, linearity, and durability results are measured and characterized. The fabricated soft sensor demonstrated excellent stability and reliability and exhibited promising sensitivity with respect to different pressures and conditions.

Factors associated with lifetime suicide attempts: findings from the bipolar disorder course and outcome study from India (BiD-CoIN study).

AIM: To evaluate the risk factors associated with lifetime suicide attempts in bipolar disorder (BD) patients. METHODOLOGY: 773 BD patients with a duration of illness of at least ten years, currently in clinical remission, were evaluated for suicidal attempts in their lifetime. Those with and without lifetime suicide attempt(s) were compared for various demographic and clinical risk factors. RESULTS: 242 (31.3%) patients had a history of at least one lifetime suicide attempt. Compared to those without lifetime suicide attempts, those with suicidal attempts were less educated, were more often females, spent more time in episodes, and had a significantly more number of total episodes (in the lifetime, first five years of illness, and per year of illness), had significantly more number of total depressive episodes (in the lifetime, first five years of illness, and per year of illness), spent more time in depressive episodes, had more severe depressive episodes, more often had depression as the first episode in the lifetime, spent more time in mania/hypomania/mixed episodes, had higher residual depressive and manic symptoms, more often had rapid cycling affective disorder pattern in the lifetime, use of cannabis in dependence pattern, had poorer insight into their illness and had a higher level of disability (especially in three out of the four domains of Indian disability evaluation assessment scale). CONCLUSIONS: About one-third of the patients with BD have at least one-lifetime suicidal attempt, and those with suicide attempts usually have a poorer course of illness.

Prevalence and association of comorbid substance dependence on the course and outcome of bipolar disorder: Findings from the bipolar disorder course and outcome study from India (BiD-CoIN study).

Aim: To evaluate the prevalence of substance use disorder (SUD) and its association with the course and outcome of bipolar disorder (BD). Materials and Methods: A total of 773 patients with BD were recruited from 14 centers in different parts of India, and they were evaluated for the prevalence of comorbid substance dependence, course and outcome, subjective cognitive functioning, and disability. Results: About one-fourth (22.9%) of the participants had one or more substance dependence. In terms of specific substance of abuse, 136 (17.6%) had nicotine dependence, 80 (10.3%) patients had alcohol dependence, 13 (1.7%) had cannabis dependence, and nine (1.2%) had opioid dependence. Compared to those without comorbid substance dependence, those with a dual diagnosis (i.e., using at least one substance in a dependent pattern) were less educated, more often males, more often currently single, more often employed, had a lower number of depressive episodes per year of illness, had a higher number of manic and mixed episodes per year of illness in the first 5 years of illness, had a higher level of disability, and more often had a history of hospitalization and a history of receiving electroconvulsive therapy (ECT); also, a higher proportion of them had manic predominant polarity, more often had recurrent mania course, and were more often receiving a combination of lithium and valproate. Conclusion: About one-fourth of BD patients have comorbid SUDs, and presence of SUD has a negative impact on the course and outcome of BD.

Predominant polarity in bipolar disorder: Findings from the bipolar disorder course and outcome study from India (BiD-CoIN study).

AIM: This cross-sectional study aimed to assess the predominant polarity (PP) in patients with bipolar disorder (BD) and the factors associated with PP. METHODOLOGY: For this study, 773 participants with at least 10 years of illness, were recruited from 14 centres, were evaluated using the National Institute of Mental Health- Retrospective Life Charts to assess the course of illness and PP was determined by both Barcelona proposal and the Harvard Index. RESULTS: According to Barcelona proposal for PP, 20.6% of the patients belonged to depressive PP, 45.8% belonged to manic PP and 33.6% belonged to indeterminate polarity. According to Harvard index of PP, 31.6% of the patients belonged to depressive PP, 56.1% belonged to manic polarity and 12.3% of the patients could not be categorized into any of these categories and hence, were considered to have indeterminate polarity. Those with depressive PP were more often having BD-II, had later age of onset, spent more time in episodes, had higher residual depressive symptoms, had lower residual manic symptoms, more often had depression as the first lifetime episode, and less often had at least one psychotic episode. CONCLUSION: In the Indian subcontinent, although the prevalence of PP is influenced by the definition used, the most common PP is that of mania.

Residual symptoms in bipolar disorders: Findings from the bipolar Disorder course and outcome study from India (BiD-CoIN study).

AIM: To explore the prevalence of residual symptoms (both depressive and manic) and their correlates in subjects with bipolar disorder in clinical remission. METHODOLOGY: This multicentric cross-sectional study included patients in clinical remission recruited across the 14 centers. The patients were evaluated on the Hamilton Depression Rating Scale (HDRS) and Young Mania Rating Scale (YMRS) for the prevalence of residual symptoms. A score of ≤7 on both scales defined the presence of residual symptoms. RESULTS: Four-fifth (79.8%) of the participants had residual symptoms, with 130 (16.8%) having only residual depressive symptoms, 74 (9.6%) having only residual manic symptoms, and 413 (53.4%) having both depressive and manic residual symptoms, on HDRS and YMRS. The residual symptoms were related to the polarity of the most recent episode and the lifetime predominant polarity. Higher numbers of lifetime depressive episodes are associated with higher residual depressive symptoms, and higher numbers of lifetime manic episodes are associated with higher chances of having residual manic symptoms. CONCLUSIONS: A large proportion of patients with bipolar disorder have residual symptoms during the remission phase. Clinicians need to make efforts to identify and address the same to improve the treatment outcome.

Is unipolar mania a distinct entity: findings from the bipolar disorder course and outcome study from India (BiD-CoIN study).

AIM: This study aimed to evaluate the prevalence of unipolar mania (UM) in a group of patients of bipolar disorder (BD). Additionally, effort was made to evaluate the demographic, clinical and treatment related factors, which distinguish subjects of UM from BD. METHODOLOGY: Seven hundred and seventy-three patients with BD, of at least 10 years duration, recruited from 14 General Hospital Units of tertiary care centers from India were evaluated for UM. RESULTS: The prevalence of UM, varied from 5.4% to 20.3%, depending on the definition used. With the most stringent definition of ≥4 episodes of mania and at least 5 years of follow-up, the prevalence of UM was 5.4%. Compared to patients of BD, who have episodes other than mania too, those with UM had lower proportion of patients with lifetime history of suicide attempts, spent less time in the episodes in their lifetime and had lower severity of residual depressive and manic symptoms. Further, compared to those with episodes other than mania too, those with UM had higher number of manic episodes per year of illness, had higher proportion of patients who had more than five episodes in the lifetime and had higher proportion of those with at least one episode with psychotic symptoms in the lifetime. CONCLUSION: The present study suggests that a small proportion of patients with BD have UM course and this runs a different clinical course compared to that seen in patients with traditionally recognized as BD.

Floating boat method for carbonate stable isotopic ratio determination in a GasBench II peripheral.

RATIONALE: Efficient high-precision stable isotope ratio determination using the GasBench II peripheral for carbonates involves loading of a reaction vial with carbonate powder and injection of phosphoric acid of high density for carbonate digestion. Herein, we present an alternative method, which bypasses the need for acid dosing with an automated pump. The advantages of the new method include minimization of clogging within capillaries caused by the acid, acid spillage, and diffusive fractionation due to repeated piercing of the septa. METHODS: The alternative method involves the use of low-cost boats preloaded with carbonate powder introduced into an Exetainer vial preinjected with phosphoric acid and placed within the compartment of a heated block maintained at a constant temperature in the GasBench II. RESULTS: The new method yielded an improvement in precision for δ13 CVPDB and δ18 OVPDB values during replicate analyses of NBS 19, with an overall precision of ±0.04‰ and ±0.06‰, respectively. The accuracy and precision of analysis using the conventional method and the floating boat method were statistically re-evaluated using a bootstrap error analysis and Monte Carlo simulation methods. CONCLUSIONS: The proposed floating boat method of acid digestion showed significant improvement in analytical procedure and overall precision. This method is easily adoptable in other laboratories and is free from frequent issues of needle clogging and irregular fractionation due to diffusion facilitated by repeated puncturing of septa, and can serve as an alternative method for high-precision carbonate stable isotope analysis.

Prescription patterns in clinically stable patients with bipolar disorder: Findings from the Bipolar Disorder Course and Outcome from India (BiD-CoIN) study.

AIM: To evaluate the prescription pattern of patients with BD, currently in clinical remission. Additional aim of the study was tocompare the prescription pattern across different study centres. METHODOLOGY: Prescription of 773 patients, currently in clinical remission, recruited from the outpatient setting of 14 General Hospital Tertiary Care Units of tertiary care centres in the country were evaluated. RESULTS: Almost all (98.1 %) participants were on medications at the time of assessment. In terms of conventional mood stabilizers, those receiving valproate (44.2 %), out-numbered those receiving lithium (38.9 %). A small proportion (7.4 %) was receiving a combination of both valproate and lithium. About two-third (62.5 %) were receiving at least one antipsychotic medication, with olanzapine (31.7 %) being the most commonly prescribed antipsychotic, followed by quetiapine (11.1 %), and risperidone (9.6 %). About one-third (34.4 %) of the participants were receiving antidepressants, with sertraline (22.6 %) forming bulk of the prescription. Less than half (43.9 %) of the participants were also receiving a benzodiazepine medication at the time of assessment, with chlordiazepoxide (18 %) being the most common agent, followed by clonazepam (14.5 %). There was variation in the prescription patterns across different centres, in terms of monotherapy, polypharmacy, use of preferred conventional mood stabilizers, use of various antipsychotics and antidepressants. CONCLUSION: Besides conventional mood stabilizers, about two-third of patients with bipolar disorder received concomitant antipsychotics, one-third received concomitant antidepressants and less than half received benzodiazepines.

Depthwise microbiome and isotopic profiling of a moderately saline microbial mat in a solar saltern.

The solar salterns in Tuticorin, India, are man-made, saline to hypersaline systems hosting some uniquely adapted populations of microorganisms and eukaryotic algae that have not been fully characterized. Two visually different microbial mats (termed 'white' and 'green') developing on the reservoir ponds (53 PSU) were isolated from the salterns. Firstly, archaeal and bacterial diversity in different vertical layers of the mats were analyzed. Culture-independent 16S rRNA gene analysis revealed that both bacteria and archaea were rich in their diversity. The top layers had a higher representation of halophilic archaea Halobacteriaceae, phylum Chloroflexi, and classes Anaerolineae, Delta- and Gamma- Proteobacteria than the deeper sections, indicating that a salinity gradient exists within the mats. Limited presence of Cyanobacteria and detection of algae-associated bacteria, such as Phycisphaerae, Phaeodactylibacter and Oceanicaulis likely implied that eukaryotic algae and other phototrophs could be the primary producers within the mat ecosystem. Secondly, predictive metabolic pathway analysis using the 16S rRNA gene data revealed that in addition to the regulatory microbial functions, methane and nitrogen metabolisms were prevalent. Finally, stable carbon and nitrogen isotopic compositions determined from both mat samples showed that the δ13Corg and δ15Norg values increased slightly with depth, ranging from - 16.42 to - 14.73‰, and 11.17 to 13.55‰, respectively. The isotopic signature along the microbial mat profile followed a pattern that is distinctive to the community composition and net metabolic activities, and comparable to saline mats in other salterns. The results and discussions presented here by merging culture-independent studies, predictive metabolic analyses and isotopic characterization, provide a collective strategy to understand the compositional and functional characteristics of microbial mats in saline environments.

Ab initio quantum chemical studies of isotopic fractionation during acid digestion reaction of dolomite for clumped isotope application.

RATIONALE: In 'clumped isotope paleothermometry' carbonates are reacted with anhydrous phosphoric acid to extract CO2 that carries the isotopic signature of the reacting carbonates, and the amount of clumping in the product CO2 is measured. Previous theoretical models for determining clumped isotopic fractionation in product CO2 during acid digestion of carbonates are independent of the cations present in the carbonate lattice. Hence further study is required to understand the cationic effect. METHODS: We studied the acid reaction mechanism based on the protonation of carbonates, calculated the acid fractionation factor for dolomite using the partition functions and vibrational frequencies obtained for the transition state structure, and determined the effect of cations on the acid fractionation factor. Experimentally, carbonates are reacted using the modified sealed vessel method and analyzed in the dual inlet of a ThermoFinnigan MAT 253 isotope ratio mass spectrometer. RESULTS: The oretically obtained acid fractionation factor can be expressed as Δ47 acid fractionation in dolomite = -0.28563 + 0.49508 * (105 /T2 ) - 0.08231 * (105 /T2 )2 for a temperature range between 278.15 and 383.15 K. The theoretical slope of the dolomite-acid digestion curve is lower than that of the calcite-acid digestion curve obtained using the identical reaction mechanism. Our theoretical slope is consistent with the result from the common acid bath experiments but higher than the slope obtained in our experimental study using the modified sealed vessel method and in a previous theoretical study using the H2 CO3 model. CONCLUSIONS: The transition state structure, obtained in our study, includes the cations present in the carbonate minerals and provides distinct acid fractionation factors for calcite and dolomite. The observed gentler slope of the theoretically calculated dolomite-acid digestion curve than of the calcite curve is expected considering the stronger Mg-O bond. Our experimental approach invokes post-digestion isotopic exchange and agrees with the previous theoretical estimates where post-digestion isotopic fractionation was considered.

Fractionation of stable oxygen and clumped isotopes during acid digestion of calcite in the presence of an external direct current electric field.

RATIONALE: Phosphoric acid digestion of carbonate generates CO2 for stable oxygen and clumped isotope analysis using a gas source isotope ratio mass spectrometer. The initial step of the digestion reaction is protonation of calcite while the product CO2 equilibrates with the system allowing further exchange of isotopes to various extents depending on the nature of the acid digestion methods. An external electric field is introduced in the break seal method to demonstrate the role of the protonation reaction and the post-digestion isotopic exchanges in the final isotopic composition of product CO2 . METHODS: An acid digestion experiment following the break seal method was conducted at a constant temperature of 25 ± 0.5°C in the presence of a uniform external electric field of 0.5 kV/cm within a specially fabricated corona chamber. Replicate samples of a calcite powder of a reference standard (MAR J1) were reacted for 24 h in the presence and absence of an external electric field for varying exposure times (6 to 24 h) and the evolved CO2 was analyzed using a dual-inlet MAT 253 isotope ratio mass spectrometer. RESULTS: The CO2 yield from the phosphoric acid digestion of MAR J1 calcite was 20% lower during the reaction in presence of an electric field for an exposure time of 24 h, while the corresponding δ18 O value and Δ47 composition were 0.3‰ and 0.1‰ less, respectively, than without any electric field. CONCLUSIONS: We documented the systematic control of oxygen and clumped isotope ratios in CO2 evolved from the carbonate acid digestion reaction with varying exposure time to the external electric field. We provide a new method involving use of an external electric field to manipulate the isotopic fractionation during the acid digestion reaction of calcite. The experimental observation enabled theoretical understanding of the reaction mechanism of carbonate with phosphoric acid which will be useful for stable and clumped isotope studies.

Isotopic fractionation during acid digestion of calcite: A combined ab initio quantum chemical simulation and experimental study.

RATIONALE: Carbonate clumped isotope analysis involves the reaction of carbonate minerals with phosphoric acid to release CO2 for measurement in a gas-source isotope ratio mass spectrometer. Although the clumped isotope proxy is based on the temperature dependence of 13 C-18 O bonding preference in the mineral lattice, which is captured in the product CO2 , there is limited information on the phosphoric acid reaction mechanism and the magnitude of clumped isotopic fractionation (mass 63 in CO3 2- to mass 47 in CO2 ) during the acid digestion. METHODS: We studied the reaction mechanism for the phosphoric acid digestion of calcite using first-principles density functional theory. We identified the transition state structures for each reaction involving different isotopologues and used the corresponding vibrational frequencies in reduced partition function theory to estimate the Δ47 acid fractionation. Experimental Δ47 data were acquired by processing the sample CO2 gas through the dual-inlet peripheral of a ThermoFinnigan MAT253 isotope ratio mass spectrometer. RESULTS: We showed that the acid digestion reaction, which results in the formation of CO2 enriched with 13 C-18 O bonds, began with the protonation of calcium carbonate in the presence of water. Our simulations yielded a relationship between the Δ47 acid fractionation and reaction temperature as Δ47 = -0.30175 + 0.57700 × (105 /T2 ) - 0.10791 × (105 /T2 )2 , with T varying between 298.15 and 383.15 K. CONCLUSIONS: We propose a reaction mechanism that shows a higher slope (Δ47 acid fractionation vs. 1/T2 curve) for the phosphoric acid digestion of calcite than in previous studies. The theoretical estimates from the present and earlier studies encapsulate experimental observations from both "sealed vessel" and "common acid bath" acid digestion methods.

Acid digestion of carbonates using break seal method for clumped isotope analysis.

RATIONALE: Acid digestion of carbonates to release CO2 is a crucial and sensitive step in sample preparation for clumped isotope analysis. In addition to data reduction and instrumental artefacts, many other uncertainties in the clumped isotope analysis of carbonates arise from the method used for the preparation of CO2 . We describe here an in-house-designed reaction vessel that circumvents degassing and contamination problems commonly associated with the McCrea-type digestion protocols. METHODS: We designed a leak-free break seal reaction vessel (made of Pyrex™) suitable for prolonged acid digestion at 25°C. Using this new vessel, several carbonate reference materials widely used in the clumped isotope community and other in-house laboratory standards were acid-digested and analysed for their δ13 C, δ18 O and Δ47 values with a dual inlet MAT 253 isotope ratio mass spectrometer following standard gas chromatography purification and data evaluation protocols. RESULTS: Long-term reproducibility in Δ47 determination was established using international references and in-house working standards as follows (mean and SE): Carrara-1 (0.395 ± 0.002‰, n = 43), Carrara-2 (0.441 ± 0.003‰, n = 22), OMC (0.587 ± 0.004‰, n = 16), NBS 19 (0.393 ± 0.005‰, n = 10), NBS 18 (0.473 ± 0.003‰, n = 5), ETH 1 (0.271 ± 0.005‰, n = 7), ETH 3 (0.698 ± 0.005‰, n = 3), MZ (0.715 ± 0.002‰, n = 3) and several others. CONCLUSIONS: A new method using a break seal tube was found to be efficient for the clumped isotope analysis of carbonates that require longer reaction time at 25°C. This method yields good precision in Δ47 analysis and was found to be suitable for acid digestions at any desired temperature.

Oxygen isotope enrichment in rice (Oryza sativa L.) grain organic matter captures signature of relative humidity.

The oxygen isotopic composition (δ18O) of plant organic matter (OM) is primarily governed by the δ18O of source water (δ18OSW) and climatic factor of relative humidity (RH). Among the cereals, the growth of rice plants is critically dependent on the water availability in the growth-environment. In the present study, we investigated the sensitivity of δ18O in the bulk organic matter of rice grains to RH of their growth-environment. Our experimental setup consisted of both glasshouse and field experiments, where eight genotypes were grown at RH levels ranging from 67% to 87%. The δ18O measured in bulk grain OM and source water was used to calculate the net oxygen isotopic enrichment (Δ18OOM). Regression analysis of Δ18OOM with RH demonstrated a significant relationship (r2 = 0.96; p < 0.0001), thereby implying that the isotopic signature of evaporative conditions gets recorded in the rice grain OM. In addition, our study involved a separate experiment that monitored the degree of oxygen isotope enrichment in water samples extracted from different parts of the rice plant. For this purpose, we sampled four of the above eight genotypes along with three other rice genotypes that were grown in both open cultivation fields and glasshouse. Water present in the culms, leaves, and grains were extracted quantitatively. Isotopic analyses revealed progressive 18O enrichment of the water in the culms and leaves and intermediate enrichment values of that in the grains. Based on the isotope data, we validated mechanistic models for prediction of δ18O of the leaf water and that of the plant carbohydrates. The model predictions were in close agreement with the experimental observations. The study provides insights into the rice plant's oxygen isotope systematics that build the foundation for future applications of the stable isotope technique to study the interactions between rice and environment.

Author Correction: Rainfall seasonality on the Indian subcontinent during the Cretaceous greenhouse.

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