Synthon Approach in Crystal Engineering to Modulate Physicochemical Properties in Organic Salts of Chlorpropamide

The formulation of drug with improved bioavailability is always challenging and indispensable in the field of pharmaceutics. The control of intermolecular interactions via crystal engineering approach and solid-state molecular recognition results in the formation of active drug molecules with modulated pharmacological benefits. Therefore, with the aim to improve the solubility and dissolution rate of the drug chlorpropamide (CPA), the mechanochemical liquid-assisted grinding (LAG) of the drug with several pharmaceutically accepted excipients was performed. This contributed to the discovery of six novel solid phases, namely salts, salt cocrystals and salt cocrystal hydrate─the salt of CPA with 3, 4-diaminopyridine (DAP); salt and salt cocrystal (SC) polymorph (Z″=3) with 1, 4-diazabicyclo [2.2.2] octane (DABCO); a salt, SC polymorph (Z″=9), and a SC hydrate (Z″=9) with piperazine (PIP). The formation of these salts and salt cocrystals are mainly guided by the strong hydrogen bonds with tunable strength having high electrostatic contribution. This attractive interaction brings the donor and the acceptor atoms close to each other for a facile proton transfer. Furthermore, the conformational constraints on the drug molecules, provided by the excipients via strong and directional hydrogen bonds, are quite impressive as this leads to the identification and characterization of "new conformational isomers" for the CPA molecules. The new crystalline phases exhibit enhanced intrinsic dissolution rate in comparison to that of the pure drug, the magnitude being 7, 131, and 120 folds for CPADAP, CPADABCO_II, and CPAPIP_III, respectively. Furthermore, it is interesting to note that the order of solubility is enhanced by 2.7-, 3-, and 7-fold, respectively, for the abovementioned salts. This also mirrors the trends in the magnitude of the binding energy, the higher magnitude being reflected in the lower solubility. Additionally, the in vivo experiments performed in SD rats results in the enhancement of the magnitude of the pharmacokinetic properties, when compared to the pristine drug. The concentration of the drug in CPADABCO_II and CPAPIP_III formulations exhibits 6- and 4-fold increments, respectively. Indeed, these results corroborate to the trends observed in the structural characterization, intermolecular energy calculations, solubility, and in vitro dissolution assessments.

Circadian-based approach for improving physiological, phytochemical and chloroplast proteome in Spinacia oleracea under salinity stress and light emitting diodes

Salt stress is a recognized annihilating abiotic stress that has a significant impact on agricultural and horticulture crop productivity. Plant development faces three distinct dangers as a result of salt stress: oxidative stress, osmotic stress, and ionic toxicity. It has been shown that plants can forecast diurnal patterns using the circadian clock; moreover, they can manage their defensive mechanism for the detoxification of reactive oxygen species (ROS). Circadian rhythmicity in gene expression assembles transcription and translation feedback networks to govern plant shape, physiology, cellular and molecular activities. Both external and internal variables influence the systemic rhythm via input routes. The Malav Jyoti (MJ) and Delhi Green (DG) genotypes of spinach (Spinacia oleracea) were grown in the plant growth chamber. The chamber had an optimized temperature of 25 °C and humidity of 65% containing light emitting diode (LED) having Red: Blue: white (one side) and White fluorescent (other side) under salinity stress. The samples were collected on the basis of 4 h intervals of circadian hours (0 h, 4 h, 8 h and 12 h) during Day-10 and Day-20 of salt treatments. Under salt stress, the circadian and light-emitting diode-based strategy had a substantial influence on spinach's anti-oxidative responses, stomatal movement, CO2 assimilation, PS-I and II efficiency, phytochrome pigment efficiency, and photosynthesis. Based on the findings of the free radical scavenging enzyme tests, the photoperiodic hours for the proteome analysis were set to 11 am and 3 pm on Day-20. When compared to white fluorescent, this study found that LED has the capacity to influence the entrainment cues of the circadian clock in the cultivation of salt-sensitive spinach genotypes. According to our findings, changing the cellular scavenging mechanism and chloroplast proteome has increased the survival rate of spinach genotypes under LED when compared to white fluorescent.

A supervised learning approach for the influence of comorbidities in the analysis of COVID-19 mortality in Tamil Nadu

COVID-19 has created many complications in today's world. It has negatively impacted the lives of many people and emphasized the need for a better health system everywhere. COVID-19 is a life-threatening disease, and a high proportion of people have lost their lives due to this pandemic. This situation enables us to dig deeper into mortality records and find meaningful patterns to save many lives in future. Based on the article from the New Indian Express (published on January 19, 2021), a whopping 82% of people who died of COVID-19 in Tamil Nadu had comorbidities, while 63 percent of people who died of the disease were above the age of 60, as per data from the Health Department. The data, part of a presentation shown to Union Health Minister Harsh Vardhan, show that of the 12,200 deaths till January 7, as many as 10,118 patients had comorbidities, and 7613 were aged above 60. A total of 3924 people (32%) were aged between 41 and 60. Compared to the 1st wave of COVID-19, the 2nd wave had a high mortality rate. Therefore, it is important to find meaningful insights from the mortality records of COVID-19 patients to know the most vulnerable population and to decide on comprehensive treatment strategies.

Highly efficient functionalized MOF-LIC-1 for extraction of U(VI) and Th(IV) from aqueous solution: experimental and theoretical studies

A set of four new functionalized MOFs, namely MOF-LIC-DPPC, MOF-LIC-GA, MOF-LIC-PCA and MOF-LIC-SA, were synthesized via the post-synthetic modification (PSM) strategy using MOF-LIC-1 for efficient extraction of U(VI) and Th(IV) from an aqueous medium. FTIR, powder XRD, TGA and SEM-EDX were employed for characterization of the functionalized MOFs. Sorption studies for U(VI) and Th(IV) were performed by monitoring the pH and contact time. Interestingly, the modified MOF-LIC-SA displayed rapid (∼5 min) and efficient extraction towards U(VI) and Th(IV) from an aqueous medium and modified MOF-LIC-DPPC displayed enhanced thermal stability (600 °C) compared with the parent MOF-LIC-1 (450 °C). These studies revealed that the grafted functionalities on MOF-LIC-1 possess enhanced sorption efficiency towards U(VI) and Th(IV) as well as thermal stability. MOF-LIC-SA exhibited the highest sorption capacity towards U(VI) and Th(IV), viz. 298 mg g^-1 (pH 6) and 149 mg g^-1 (pH 6), respectively. Leaching, recyclability, and radiation stability studies were also performed using MOF-LIC-1 MOFs. Additionally, we investigated the nature of U(VI) interactions on MOFs by applying density functional theory (DFT). PSM MOFs with various functionalities display high selectivity and efficient extraction of U(VI) and Th(IV) over a wide pH range (2-9) and also exhibit easy recovery of metal ions from MOFs. These studies reveal that U(VI) and Th(IV) can be extracted from aqueous streams in a pH range from 6 to 8 and potential applications of these MOFs include recovery of U(VI) and Th(IV) from mine water, sea water, etc. The studies reported in the present work also have extensive potential applications for environmental concerns as well as in the nuclear industry.

PCSK9 inhibitor therapy and guideline treatment targets for cardiovascular disease and familial hypercholesterolaemia

Background

Updated trial data on the benefits of low-density lipoprotein cholesterol (LDL-C) reduction on cardiovascular outcomes have been incorporated into 2019 ESC/EAS guidelines and 2020 UK-based NICE guidance. Treatment targets for secondary cardiovascular disease (CVD) prevention are LDL-C <1.4mmol/L (ESC/EAS) and non-high-density lipoprotein <2.5mmol/L (equates to LDL-C <1.8mmol/L; NICE). Guidelines also recommend ≥50% LDL-C reduction in patients with CVD or Familial Hypercholesterolaemia (FH). Targets are often not achieved with oral statin +/− ezetimibe due to reduced efficacy or tolerability, warranting a switch to PCSK9 inhibitor therapy. However, there is limited data on whether this achieves LDL-C targets for both CVD and FH in real world clinical practice.

Purpose

To assess attainment of LDL-C treatment targets using PCSK9 inhibitor mono- or combination therapy in routine clinical care for patients with FH or CVD.

Methods

Observational study in a single specialist lipid clinic, using retrospective case note review of patients prescribed PCSK9 inhibitor therapy according to NICE guidelines until February 2021. Anonymised clinical, demographic and biochemical data before and after commencement of PCSK9 inhibitor therapy were collected. Primary outcomes were attainment of guideline-defined LDL-C treatment targets: LDL-C <1.8 mmol/L, LDL-C <1.4mmol/L and ≥50% LDL-C reduction.

Results

A total of 55 patients (mean age 60.8±12.9 years, 58% male) on PCSK9 inhibitor therapy (98% alirocumab, 2% evolocumab; mean treatment duration 1.7±1.3 years) were identified. PCSK9 inhibitor therapy was commenced due to drug intolerance to statins (89%), ezetimibe (36%) and fenofibrate (25%). In patients with FH (n=18), 78%, 56% and 33% of patients achieved targets of ≥50% LDL-C reduction, LDL-C <1.8 mmol/L and LDL-C <1.4 mmol/L on treatment, respectively. In CVD patients (n=49), 84%, 51% and 27% achieved the same targets respectively (Table 1). In patients on PCSK9 inhibitor monotherapy (n=19), 21% and 5% achieved LDL-C targets <1.8 mmol/L and <1.4 mmol/L respectively, whereas in those on PCSK9 inhibitor + two or more additional oral lipid-lowering therapies, 87% and 60% achieved the same targets respectively (Table 2).

Conclusions

Most patients with FH or CVD achieve an LDL-C reduction of ≥50% from baseline with PCSK9 inhibitor therapy, however fewer achieve the LDL-C targets of <1.8 mmol/L or <1.4 mmol/L. Patients on PCSK9 inhibitor monotherapy are unlikely to reach LDL-C <1.8 mmol/L and <1.4mmol/L targets, whereas PCSK9 inhibitor combination therapies are more likely to do so. Additional lipid-lowering drugs are required with PCSK9 inhibitor therapy in most patients to reach guideline LDL-C targets.

Funding Acknowledgement

Type of funding sources: None.

1599 Review of Telephone Consultations for Suspected Head and Neck Cancer Referrals During The COVID-19 Pandemic

Introduction

Pandemic COVID-19 necessitated a transformation in the delivery of healthcare. Telephone consultations were introduced to protect and progressively manage patients with minimal delay. This is a review of the effectiveness of these remote consultations for suspected 2-week wait (2ww) head and neck cancer referrals to a north London NHS teaching hospital Oral and Maxillofacial unit during the first official UK government lockdown from March - July 2020.

Method

Prospective electronic records of 176 consecutive 2ww referrals between March – July 2020 was assessed. Data analysed included initial telephone consultations, subsequent face-to-face (F2F) appointments, if required, the interval from telephone to F2F appointments and histopathological diagnoses.

Results

157 patients (n = 176) received an initial telephone call, of which 127 (80.9%) required a F2F consultation. The number of days between the initial telephone consultation and subsequent F2F assessment ranged from 0 to 141, with a mean of 11 and a median of 1. Notably, 31 patients (24.4%) were seen in person on the same day as their telephone consultation. Biopsies were indicated for 69 patients (54.3%) of which 9 (13.0%) were diagnosed as malignancies.

Conclusions

Whilst protecting patients from a pandemic is utmost, continuing care for non-pandemic conditions must be considered. It is even more important to manage 2ww referrals efficiently. These results indicate the majority of suspected cancer referrals warrant F2F assessment for a confident outcome. Despite reinstated, ongoing social restrictions, 2ww referrals are now being seen exclusively F2F, subject to patient choice. This information is useful for planning and strategizing services in a head and neck OMFS unit.

Third phase formation behaviour of tris(2-methylbutyl) phosphate and tri-n-alkyl phosphates in the extraction of mineral acids and tetravalent metal ions

The formation of third phase is a detrimental phenomenon witnessed in the nuclear separation processes during the extraction of certain metal salts by an organic solution, which comprises of a neutral extractant, tri-n-butyl phosphate dispersed in a non-polar diluent, n-dodecane (n-C12H26). In the present work, a comparative analysis on the third phase formation behaviour of three trialkyl phosphates, TBP, its linear and branched higher homologues tri-n-amyl phosphate and tris(2-methylbutyl) phosphate (T2MBP), respectively, have been provided which will be useful for the identification of an extractant with minimum third phase formation tendency. The organic phase splitting behaviour during the extraction of three mineral acids (HClO4, HCl and HNO3) and two tetravalent metal nitrates (Th(IV) and Zr(IV)) by trialkyl phosphates has been investigated to understand the influence of anionic and cationic components, respectively, in third phase formation of trialkyl phosphates. The effect of structure of the alkyl groups of trialkyl phosphate and chain length of diluents on third phase formation during Zr(IV) extraction from HNO3 media have also been studied. Overall, the third phase formation behaviour of T2MBP was found to be lower both for the extraction of mineral acid and Zr(IV), thereby indicating its potentiality for applications in various solvent extraction processes.

Post synthetically modified IRMOF-3 for efficient recovery and selective sensing of U(vi) from aqueous medium

A simple and efficient route to develop various novel functionalized MOF materials for rapid and excellent recovery of U(vi) from aqueous medium, along with selective sensing has been demonstrated in the present study. In this connection, a set of four distinct post synthetically modified (PSM) iso-reticular metal organic frameworks were synthesized from IRMOF-3 namely, IRMOF-PC (2-pyridine carboxaldehyde), IRMOF-GA (glutaric anhydride), IRMOF-SMA (sulfamic acid), and IRMOF-DPC (diphenylphosphonic chloride) for the recovery and sensing of U(vi) from aqueous medium. The MOFs were characterized by Fourier transform infrared spectroscopy (FTIR), powder XRD, BET surface area analysis, thermogravimetric analysis (TGA), NMR (¹³C, ¹H and ³¹P), Scanning Electron Microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). Among all MOFs, post synthetically modified IRMOF-SMA showed enhanced thermal stability of about 420 °C. The MOFs were investigated for U(vi) sorption studies using a batch technique. All the MOFs exhibit excellent sorption capacity towards U(vi) (>90%) and maximum uptake was observed at pH 6. Sorption capacity of MOFs have the following order; IRMOF-3-DPC (300 mg U g^-1) > IRMOF-SMA (292 mg U g^-1) > IRMOF-PC (289 mg U g^-1) > IRMOF-GA (280 mg U g^-1) > IRMOF-3 (273 mg U g^-1). IRMOF-DPC shows rapid sorption of uranium within 5 min with excellent uptake of U(vi) (>99%). The desorption of U(vi) was examined with different eluents and 0.01 M HNO₃ was found to be most effective. The fluorescence sensing studies of U(vi) via IRMOF-3 and its PSM MOFs revealed high sensitivity and selectivity towards U(vi) over other competing rare earth metal ions (La³⁺, Ce⁴⁺, Sm³⁺, Nd³⁺, Gd³⁺, and Eu³⁺), wherein IRMOF-GA displayed an impressive detection limit of 0.36 mg L^-1 for U(vi).

Patients' views on a proposed oral cancer screening technology

Brush cytology and telemedicine platforms are used with proven benefits in remote diagnosis of malignancies like cervical cancer. In low-resource settings access to the current standard of care, biopsy and histopathology grading of oral lesions, can be unfeasible. Risk-stratifying early malignant and oral potentially-malignant lesions can help instigate therapeutic treatment and improve prognosis. Therefore, a telecytology platform enabling remote connectivity to specialist centres may aid early detection of oral cancer. We outline head and neck (H&N) cancer patients' views on an oral brush cytology investigation.

Nonclinical Features in Predictive Modeling of Cardiovascular Diseases: A Machine Learning Approach

BACKGROUND

In the broader healthcare domain, the prediction bears more value than an explanation considering the cost of delays in its services. There are various risk prediction models for cardiovascular diseases (CVDs) in the literature for early risk assessment. However, the substantial increase in CVDs-related mortality is challenging global health systems, especially in developing countries. This situation allows researchers to improve CVDs prediction models using new features and risk computing methods. This study aims to assess nonclinical features that can be easily available in any healthcare systems, in predicting CVDs using advanced and flexible machine learning (ML) algorithms.

METHODS

A gender-matched case-control study was conducted in the largest public sector cardiac hospital of Pakistan, and the data of 460 subjects were collected. The dataset comprised of eight nonclinical features. Four supervised ML algorithms were used to train and test the models to predict the CVDs status by considering traditional logistic regression (LR) as the baseline model. The models were validated through the train-test split (70:30) and tenfold cross-validation approaches.

RESULTS

Random forest (RF), a nonlinear ML algorithm, performed better than other ML algorithms and LR. The area under the curve (AUC) of RF was 0.851 and 0.853 in the train-test split and tenfold cross-validation approach, respectively. The nonclinical features yielded an admissible accuracy (minimum 71%) through the LR and ML models, exhibiting its predictive capability in risk estimation.

CONCLUSION

The satisfactory performance of nonclinical features reveals that these features and flexible computational methodologies can reinforce the existing risk prediction models for better healthcare services.

Conformational topography of tris(2-methylbutyl) phosphate and the influence of methyl branching at the non-hyperconjugative carbon on the conformational landscape: insights from matrix isolation infrared spectroscopy and DFT computations

The branching of a methyl group in a linear chain has a profound influence on the conformational morphology as it wields a strong control in reducing a large number of conformations. To unravel the effect of branching on the second non-hyperconjugative carbon atom on the conformational landscape, the conformations of tris(2-methylbutyl)phosphate (T2MBP) were studied using Density Functional Theory (DFT) computations and matrix isolation infrared spectroscopy. Experimentally, T2MBP along with N₂/Ar/Kr/Xe gases was effusively expanded and deposited at a low temperature of 12 K, which was subsequently probed using infrared spectroscopy. The computations of all the conformations were accomplished using the B3LYP level of theory with the 6-311++G(d,p) basis set. A dimethyl(2-methylbutyl) phosphate (DM2MBP) prototype, a molecule containing a single 2-methylbutyl moiety, was examined for its conformations. Computations predicted 18 and 9 conformations each for the 'gauche' and 'trans' families, respectively, in which the third branched carbon completely influences the orientation of the fourth carbon, which simplifies the conformational problem of DM2MBP. Of the 18 and 9 bunches each in the 'gauche' and 'trans' families, only 7 and 3 conformations, respectively, became energetically important, which when extrapolated to T2MBP resulted in 343 and 147 conformational possibilities. The factor of degeneracy further reduced these numbers and a total of 168 conformations effectively contribute to the conformational composition of T2MBP in the gas phase. The role of stereo electronic and steric factors prevalent in the conformational clusters of T2MBP was unravelled respectively using natural bond orbital and non-covalent interaction analyses.

Comparison of Ultrasonography with Conventional Radiography in Diagnosis of Zygomatic Complex Fractures

Introduction

The diagnosis of zygomatic complex fractures is important in planning the treatment since the complex gives form to the projection, width and height of the midface.

Aim

This study was carried out to assess the diagnostic sensitivity and utility of high-resolution ultrasonography in comparison with conventional radiography in the diagnosis of the zygomatic complex fractures.

Materials and Method

Twenty-five cases of clinically diagnosed zygomatic complex fractures were subjected to conventional radiographs and USG study.

Results

The accuracy in terms of specificity and sensitivity of USG was comparable to conventional radiographs in the detection of the fractures of the zygomatic complex.

Conclusion

This study points to the suitability of USG as an alternative to the use of plain radiographs in the diagnosis of zygomatic complex fractures. USG is safe, inexpensive and an accurate adjunct to conventional radiography in diagnosis of zygomatic complex fractures.

Assorted functionality-appended UiO-66-NH2 for highly efficient uranium(vi) sorption at acidic/neutral/basic pH

Eight assorted functionalities were anchored on UiO-66-NH₂via PSM strategy displaying MOFs with similar framework but variable uranyl binding affinities. The excellent sorption capacity of UiO-66-PO-Ph makes it efficient uranium sorbent material.

Burden of dengue infection in India, 2017: a cross-sectional population based serosurvey

BACKGROUND

The burden of dengue virus (DENV) infection across geographical regions of India is poorly quantified. We estimated the age-specific seroprevalence, force of infection, and number of infections in India.

METHODS

We did a community-based survey in 240 clusters (118 rural, 122 urban), selected from 60 districts of 15 Indian states from five geographical regions. We enumerated each cluster, randomly selected (with an Andriod application developed specifically for the survey) 25 individuals from age groups of 5-8 years, 9-17 years, and 18-45 years, and sampled a minimum of 11 individuals from each age group (all the 25 randomly selected individuals in each age group were visited in their houses and individuals who consented for the survey were included in the study). Age was the only inclusion criterion; for the purpose of enumeration, individuals residing in the household for more than 6 months were included. Sera were tested centrally by a laboratory team of scientific and technical staff for IgG antibodies against the DENV with the use of indirect ELISA. We calculated age group specific seroprevalence and constructed catalytic models to estimate force of infection.

FINDINGS

From June 19, 2017, to April 12, 2018, we randomly selected 17 930 individuals from three age groups. Of these, blood samples were collected and tested for 12 300 individuals (5-8 years, n=4059; 9-17 years, n=4265; 18-45 years, n=3976). The overall seroprevalence of DENV infection in India was 48·7% (95% CI 43·5-54·0), increasing from 28·3% (21·5-36·2) among children aged 5-8 years to 41·0% (32·4-50·1) among children aged 9-17 years and 56·2% (49·0-63·1) among individuals aged between 18-45 years. The seroprevalence was high in the southern (76·9% [69·1-83·2]), western (62·3% [55·3-68·8]), and northern (60·3% [49·3-70·5]) regions. The estimated number of primary DENV infections with the constant force of infection model was 12 991 357 (12 825 128-13 130 258) and for the age-dependent force of infection model was 8 655 425 (7 243 630-9 545 052) among individuals aged 5-45 years from 30 Indian states in 2017.

INTERPRETATION

The burden of dengue infection in India was heterogeneous, with evidence of high transmission in northern, western, and southern regions. The survey findings will be useful in making informed decisions about introduction of upcoming dengue vaccines in India.

FUNDING

Indian Council of Medical Research.

A Novel Internet of Things Framework Integrated with Real Time Monitoring for Intelligent Healthcare Environment

During mammogram screening, there is a higher probability that detection of cancers is missed, and more than 16 percentage of breast cancer is not detected by radiologists. This problem can be solved by employing image processing algorithms which enhances the accuracy of the diagnostic through image segmentation which reduces the misclassified malignant cancers. By employing segmentation, the unnecessary regions in the breast close to the boundary between the breast tissue and segmented pectoral muscle can be removed, therefore enhancing the accuracy the calculation as well as feature estimation. In-order to enhance the accuracy of classification, the proposed classifier integrates the decision trees and neural network into a system to report the progress of the breast cancer patients in an appropriate manner with the help of technology used in healthcare system. The proposed classifier successfully demonstrated that it achieved more accurate prediction when compared with other widely used algorithms, namely, K-Nearest Neighbors, Support Vector Machine and Naive Bayes algorithm.

Evaluation of polybenzimidazole-based polymers for the removal of uranium, thorium and palladium from aqueous medium

Four types of polybenzimidazole (PBI)-based polymers (m-PBI, p-PBI, pyridine-based m-PBI and alkylated m-PBI) have been prepared and characterized. Extraction behaviour of heavy metal ions, viz. U(VI), Th(IV) and Pd(II), with these polymers was investigated. Distribution ratios for the extraction of these metal ions were measured as a function of nitric acid concentration. Extraction data reveal that, in general, p-PBI exhibits a higher distribution ratio for U(VI), Th(IV) and Pd(II) compared with the other polymeric resins evaluated in the present study. Column chromatography experiments were carried out with a solution of U(VI), Th(IV) and Pd(II) in dilute nitric acid media using columns packed with m- and p-PBI polymeric material for understanding the sorption and elution behaviour. The p-PBI-based resin has shown higher palladium sorption capacity (1.8 mmol g^-1). The studies also established that p-PBI resin is a potential candidate material for the recovery of U(VI) and Th(IV) (capacity 0.22 mmol g^-1 and 0.13 mmol g^-1) from an aqueous stream, e.g. mine water samples.

Gastric lipoma: a rare cause of haematemesis

Gastric lipomas are rare benign tumours of the stomach, representing less than 3% of all benign gastric neoplasms. They are usually asymptomatic but larger lesions can present with abdominal pain, gastric outlet obstruction and haematemesis. Malignant transformation is extremely rare. Accurate preoperative diagnosis can be established with computed tomography. Being benign, extensive surgery is not necessary and simple excision of the lesion is adequate. Small asymptomatic lesions can be followed up. We present a case of 80-year-old woman with gastric submucosal lipoma who presented with haematemesis.

Effects of temperature on the extraction of U(VI) and Pu(IV) by tris(2-methylbutyl) phosphate from nitric acid media

Extraction behavior of tris(2-methylbutyl) phosphate (T2MBP), a higher homologue of tri-n-butyl phosphate (TBP), in the extraction of U(VI) and Pu(IV) from nitric acid media has been evaluated in the present study. Distribution ratios for the extraction of these metal ions by T2MBP were measured as a function of equilibrium aqueous phase nitric acid concentration, extractant concentration and temperature to understand the temperature effects on extraction. Enthalpies of extraction of T2MBP/n-dodecane-U(VI)-HNO3 and T2MBP/n-dodecane-Pu(IV)-HNO3 systems were calculated from the distribution ratio data using “second law” method. The data reveal that the extraction of U(VI) by T2MBP is exothermic in nature, whereas that of Pu(IV) is endothermic.

Physicochemical properties and radiolytic degradation studies on tri-iso-amyl phosphate (TiAP)

The solvent composed of tri-iso-amyl phosphate (TiAP) in n-dodecane (n-DD) is regarded as a promising candidate for reprocessing of spent fuel. In this context, the radiolytic degradation of a solution of TiAP in n-dodecane was investigated by irradiating the solvent to various absorbed dose levels of γ-radiation. The neat extractant or a solution of extractant in n-dodecane was irradiated in the presence of nitric acid. Physicochemical properties such as density, viscosity and interfacial tension (IFT) were measured for unirradiated and irradiated solutions. The extent of degradation was determined by measuring the variation in extraction behavior of U(VI) and Pu(IV) with irradiated solvent systems. Uranium and plutonium retention with irradiated solvents was also measured. The distribution ratio of uranium and plutonium increased with increase in absorbed dose. Effect of alpha degradation was studied by plutonium retention as a function of time using 1.1 M TiAP/n-DD. Laser desorption/ionization mass spectrometric technique was employed to identify the possible radiolytic degradation products. Similar studies were also carried out with tri-n-butyl phosphate (TBP) based solvent system under identical experimental conditions and the results are compared.

Comparision in the solvent extraction behavior of uranium (VI) in some trialkyl phosphates in ionic liquid

Higher homologs of trialkyl phosphates (TAlP) are proposed for reprocessing of fast reactor fuels. Solvent extraction behavior of U(VI) from nitric acid medium was studied in some TAlP present in 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C8mim][NTf2]) ionic liquid. The extractants investigated were tri-n-propylphosphate (TPP), tri-n-butylphosphate (TBP), tri-n-amylphosphate (TAP), tri-n-octylphosphate (TOP), tri-iso-amylphosphate (TIAP) and tri-iso-butylphosphate (TIBP). The extraction of uranium (VI) was investigated as a function of various parameters, such as the equilibration time, [HNO3], [TAlP], temperature and nature of ionic liquid cation. The distribution ratios of U(VI) increased with an increase in the concentration of nitric acid and decreases in the order TOP>TAP~ TIAP>TBP~TIBP>TPP. The stoichiometry of the extraction was determined by slope analysis of the extraction data. Distribution ratios of U (VI) were determined at various temperatures and the thermodynamic parameters were derived. Quantitative stripping of uranium from the loaded ionic liquid phase was achieved using dilute nitric acid.