Association of common variants of TCF7L2 and PCSK2 with gestational diabetes mellitus in West Bengal, India.

The genetic etiology of gestational diabetes mellitus (GDM) was suggested to overlap with type-2 diabetes(T2D). Transcription factor 7-like 2 (TCF7L2) and Proprotein Convertase Subtilisin/Kexin type 2 (PCSK2) are T2D susceptibility genes of the insulin synthesis/processing pathway. We analyzed associations of TCF7L2 and PCSK2 variants with GDM risk and evaluated their potential impact on impaired insulin processing in an eastern Indian population. The study included 114 GDM (case) and 228 non-GDM pregnant women (control). rs7903146, rs4132670, rs12255372 of TCF7L2, and rs2269023 of PCSK2 were genotyped by PCR-RFLP, and genotype distributions were compared between case and control. Fasting serum proinsulin and C-peptide levels were measured by ELISA and the Proinsulin/C-peptide ratio was considered an indicator of proinsulin conversion. Significantly higher frequency of risk allele (T) of rs12255372 (p = 0.02, OR = 2.0, 95%CI = 1.11-3.64) and rs4132670 (p = 0.002, OR = 2.26, 95%CI = 1.32-3.87) of TCF7L2 was found in GDM cases than non-GDM controls; TT genotype was associated with significantly increased disease risk. In rs7903146 (TCF7L2) and rs2269023 (PCSK2), although the frequency of risk allele (T) was not significantly higher in cases than controls, an association of TT for both variants remained significant with higher GDM risk in the recessive model. Increased serum pro-insulin and proinsulin:c-peptide ratio was found in GDM than non-GDM women and the phenomenon showed significant association with careers of risk alleles for TCF7L2 variants. In conclusion, TCF7L2 and PCSK2 variants are related to GDM risk in the studied population and hence may serve as potential biomarkers for assessing the disease risk. TCF7L2 variants contribute to impaired insulin processing.

Predicting the pair correlation functions of silicate and borosilicate glasses using machine learning.

Glasses offer a broad range of tunable thermophysical properties that are linked to their compositions. However, it is challenging to establish a universal composition-property relationship of glasses due to their enormous compositions and chemical space. Here, we address this problem and develop a metamodel of the composition-atomistic structure relationship of a class of glassy materials via a machine learning (ML) approach. Within this ML framework, an unsupervised deep learning technique, viz., a convolutional neural network (CNN) autoencoder, and a regression algorithm, viz. random forest (RF), are integrated into a fully automated pipeline to predict the spatial distribution of atoms in a glass. The RF regression model predicts the pair correlation function of a glass in a latent space. Subsequently, the decoder of the CNN converts the latent space representation to the actual pair correlation function of the given glass. The atomistic structures of silicate (SiO2) and sodium borosilicate (NBS) based glasses with varying compositions and dopants are collected from molecular dynamics (MD) simulations to establish and validate this ML pipeline. The model is found to predict the atom pair correlation functions for many unknown glasses very accurately. This method is very generic and can accelerate the design, discovery, and fundamental understanding of the composition-atomistic structure relationship of glasses and other materials.

Uniqueness of Nanoscale Confinement for Fast Water Transport: Effect of Nanotube Diameter and Hydrophobicity.

Inspired by the enhanced water permeability of carbon nanotubes (CNTs), molecular dynamics simulations were performed to investigate the transport behavior through nanotubes made of boron nitride (BNNT), silicon carbide (SiC), and silicon nitride (SiN) alongside carbon nanotubes (which have different hydrophobic attributes) considering their implication for reverse osmosis (RO) membranes under different practical environments. According to our findings, not only do CNTs but also other kinds of nanotubes exhibit transition anomalies with increasing diameter. Utilizing the robust two-phase thermodynamic (2PT) methods, the current examinations shed light on thermodynamic origin of favorable water filling of these nanotubes. The results show that regardless of the nanotube material, the filling of water inside small nanopores (d < 10 Å) as well as within pores of diameter larger than 15 Å will always be favored by the entropy of filling. However, the entropic preference for filling nanotubes with a diameter of 10-15 Å depends on the constituent material. In particular, the enhancement in total entropy of confined water was mainly due to the increased rotational freedom of confined water molecules. The thermodynamic origin of water transport was correlated with the structural and fluidic behavior of water inside these nanotubes. The observed data for density, flow, structure correlation functions, water-water coordination, tetrahedral order parameter, hydrogen bonds, and density of states functions quantitatively support the observed entropy behavior. Of critical importance is that the present study demonstrates the effectiveness of RO filtration using nanotubes of boron nitride rather than carbon. Furthermore, it was found that one should avoid the use of silicon nanotubes unless filtration needs to be performed under harsh environments where nanotube of other materials cannot survive. Specifically, the results show that both the structural and dynamic properties of water confined in BNNTs are similar to those of CNT's, and for SiNT it is similar as SiC. Our results show that besides the nanotube material, the chirality index of the nanotube also plays a significant role in determining the structure, dynamics and thermodynamics of confined water molecules.

Acute Presentation of Asymptomatic Giant Endometrioma in Pregnancy: A Case Report.

Endometriomas are associated with severe endometriosis and are uncommon in asymptomatic women. Reported cases of giant endometriomas are few especially in pregnancy. Decidualization of endometriomas can mimic malignancies in pregnancy. Fetal outcomes can be good after excision of large endometriomas in the 2nd trimester. We present a case of giant endometrioma diagnosed in an asymptomatic woman who developed symptoms after becoming pregnant. Clinical findings, investigations, and histopathology were consistent with ovarian endometrioma. Maternal and fetal outcomes were good after the excision of the mass.

A Rare Case of Small-Cell Neuroendocrine Cancer of the Cervix: An Unexpected Diagnosis.

Cervical cancer is a significant healthcare problem worldwide, especially in developing countries. It is the second most common cause of cancer-related deaths in women. Small-cell neuroendocrine cancer of the cervix (SCNCC) accounts for about 1-3% of all cervical cancers. In this report, we present a case of a patient with SCNCC, whose disease had metastasized to the lungs even without an obvious growth in the cervix. A 54-year-old multiparous woman presented with post-menopausal bleeding for 10 days; she had a history of a similar episode in the past. Examination revealed an erythematous posterior cervix and upper vagina without any obvious growth. Histopathology showed SCNCC on the biopsy specimen. Following further investigations, the stage assigned was IVB, and she was started on chemotherapy. SCNCC is an extremely rare but highly aggressive type of cervical cancer and it requires a multidisciplinary therapeutic approach for an optimal standard of care.

Histone Deacetylase Inhibitors as Cognitive Enhancers and Modifiers of Mood and Behavior.

BACKGROUND: Epigenetic regulation of gene signalling is one of the fundamental molecular mechanisms for the generation and maintenance of cellular memory. Histone acetylation is a common epigenetic mechanism associated with increased gene transcription in the central nervous system (CNS). Stimulation of gene transcription by histone acetylation is important for the development of CNS-based long-term memory. Histone acetylation is a target for cognitive enhancement via the application of histone deacetylase (HDAC) inhibitors. The promising potential of HDAC inhibitors has been observed in the treatment of several neurodevelopmental and neurodegenerative diseases. OBJECTIVE: This study assessed the current state of HDAC inhibition as an approach to cognitive enhancement and treatment of neurodegenerative diseases. Our analysis provides insights into the mechanism of action of HDAC inhibitors, associated epigenetic priming, and describes the therapeutic success and potential complications after unsupervised use of the inhibitors. RESULTS AND CONCLUSION: Several chromatin-modifying enzymes play key roles in the regulation of cognitive processes. The importance of HDAC signaling in the brain is highlighted in this review. Recent advancements in the field of cognitive epigenetics are supported by the successful development of various HDAC inhibitors, demonstrating effective treatment of mood-associated disorders. The current review discusses the therapeutic potential of HDAC inhibition and observed complications after mood and cognitive enhancement therapies.

The Unforeseen Impact of the COVID-19 Pandemic on Dismal Pregnancy and Fetal Outcomes.

India noticed a surge in maternal mortality and stillbirth rate during the COVID-19 pandemic. This rise in mortality is not always due to viral infection by COVID-19 but is probably contributed by other determinants. We present a case of maternal mortality with stillbirth in a multigravida, at 41 weeks' gestation, with bronchial asthma, severe preeclampsia, fetal bradycardia, severe symptoms of flu infection, and a previous cesarean delivery. She delivered a stillborn baby by emergency cesarean delivery and due to adverse obstetric consequences, she succumbed. Disruption of the overwhelmed healthcare system to cope with the COVID-19 pandemic has caused unsupervised pregnancy, unprecedented delays in reaching the hospital, delays in receiving proper care, and suboptimal care due to difficulty in differentiating actual severe preeclampsia from COVID-19-induced preeclampsia-like syndrome have resulted in preventable maternal mortality and stillbirth.

Gossypol and Its Natural Derivatives: Multitargeted Phytochemicals as Potential Drug Candidates for Oncologic Diseases.

Despite the vast amounts of research and remarkable discoveries that have been made in recent decades, cancer remains a leading cause of death and a major public health concern worldwide. Gossypol, a natural polyphenolic compound derived from the seeds, roots, and stems of cotton (Gossypium hirsutum L.), was first used as a male contraceptive agent. Due to its diverse biological properties, including antifertility, antiviral, antioxidant, antibacterial, antimalarial, and most notably antitumor activities, gossypol has been the subject of numerous studies. Nevertheless, no systematic review has been performed that analyzes the antineoplastic potential of gossypol and related natural compounds in an organ-specific manner while delineating the molecular mechanisms of action. Hence, we have performed an extensive literature search for anticancer properties of gossypol and their natural derivatives against various types of cancer cells utilizing PubMed, ScienceDirect, Google Scholar, and Scopus. The sources, distribution, chemical structure, and toxicity of gossypol and its constituents are briefly reviewed. Based on emerging evidence, gossypol and related compounds exhibit significant antineoplastic effects against various cancer types through the modulation of different cancer hallmarks and signaling pathways. Additionally, the synergistic activity of gossypol and its derivatives with chemotherapeutic agents has been observed. Our evaluation of the current literature suggests the potential of gossypol and its derivatives as multitargeting drug candidates to combat multiple human malignancies.

Aggregation Behavior of Nitrilotriacetamide (NTAmide) Ligands in Thorium(IV) Extraction from Acidic Medium: Small-Angle Neutron Scattering, Fourier Transform Infrared, and Theoretical Studies.

Two tripodal amides obtained from nitrilotriacetic acid with n-butyl and n-octyl alkyl chains (HBNTA(LI) and HONTA(LII), respectively) were studied for the extraction of Th(IV) ions from nitric acid medium. The effect of the diluent medium, i.e., n-dodecane alone and a mixture of n-dodecane and 1-decanol, onto aggregate formation were investigated using small angle neutron scattering (SANS) studies. In addition, the influence of the ligand structure, nitric acid, and Th(IV) loading onto ligand aggregation and third-phase formation tendency was discussed.The LI/LII exist as monomers (aggregarte radius for LI: 6.0 Å; LII:7.4 Å) in the presence of 1-decanol, whereas LII forms dimers (aggregarte radius for LII:9.3 Å; LI does not dissolve in n-dodecane) in the absence of 1-decanol. The aggregation number increases for both the ligands after HNO3 and Th(IV) loading. The maximum organic concentration (0.050 ± 0.004 M) of Th(IV) was reached without third-phase formation for 0.1 M LI/LII dissolved in 20% isodecanol +80% n-dodecane. The interaction of 1-decanol with LII and HNO3/Th(IV) with amidic oxygens of LI/LII results in shift of carbonyl stretching frequency, as shown by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) studies. The structural and bonding information of the Th-LI/LII complex were derived from the density functional theoretical (DFT) studies. The molecular dynamics (MD) simulations suggested that the aggregation behavior of the ligand in the present system is governed by the population of hydrogen bonds by phase modifier around the ligand molecules. Although the theoretical studies suggested higher Gibbs free energy of complexation for Th4+ ions with LI than LII, the extraction was found to be higher with the latter, possibly due to the higher lipophilicity and solubility of the Th-LII aggregate in the nonpolar media.

Tuning Network Connectivity of Silicate and Sodium Borosilicate Glasses by TiO2 for Enhanced Chemical Durability: Molecular Dynamics Simulation Investigations.

Extensive molecular dynamics (MD) simulations were performed to disclose the beneficial aspects of TiO2 doping in SiO2 and sodium borosilicate (NBS) glasses. Significant amendment in short- and intermediate-range orders of glasses was captured by the radial distribution function, coordination number, bond/angle distribution profiles, structure factor, and probability of linking X-O-X' (where X and/or X' = Si, B, and Ti) structural motifs. Successively, the effect of microscopic structural modification on the macroscopic properties was analyzed in terms of mechanical strength, thermal stability, vibrational characteristics [(vibrational density of states (VDOS)], and chemical durability. The results show that Ti participates in the network chain in the form of TiO6 and TiO5 for the Ti-NBS glass whereas in the form of TiO6, TiO5, and TiO4 for the binary TiO2-SiO2 glass. The presence of TiO2 was found to strengthen the glass skeleton. However, the glass-transition temperature was also increased with Ti addition, which indicates increased hurdles during synthesis due to increased cross connections in the glass network with Ti doping. The computed results envisage enhanced chemical durability of Ti-added glasses. In addition, VDOS spectra showed network former-like characteristics of Ti in the glass network with significant contributions up to a vibration frequency of 800 cm-1. The strong binding of Ti-O-connected Na+ in the glass skeleton prevents Na+ migration toward the interface or bulk aqueous phase, which contributes to improved chemical stability of Ti-containing glasses. During contact with water, Na+ were less likely to leach out from glass to the aqueous solution during Ti doping. In addition, the increased fraction of stable ring structures (5m-7m) for Ti-NBS glasses than bare NBS glasses also supports the increased leaching resistivity of Ti-added glasses. Essentially, the elucidation of macroscopic glass properties has been provided in terms of microscopic understanding. The present findings will incite further MD simulations and experiments to disclose more interesting microstructures and dynamics due to the presence of TiO2 in glasses.

Importance of Indazole against Neurological Disorders.

Indazole is a nitrogen-containing bicyclic compound, having three tautomeric forms: 1Hindazole, 2H-indazole, and 3H-indazole. Mostly, they are considered as 1H-indazole tautomeric forms, although they have the potential to tautomerism to 2H- and 3H-indazole forms. Indazoles are involved in a wide variety of biological and enzymatic processes. Therefore, they exhibit a series of pharmacological activities. Indazoles show potent activities against neurological disorders such as Parkinson's disease (PD), Alzheimer's disease (AD), mood disorders, etc., by inhibiting different signaling pathways and the generation of neurotransmitters and activation of enzyme activity. They effectively prevent neurological diseases by different mechanisms, such as by inhibiting the monoamine oxidase (MAO) and kinase enzymes like Glycogen synthase kinase 3 (GSK3), and leucinerich repeat kinase enzyme 2 (LRRK2). In this article, we have discussed multiple causative strategies of indazole to treat neurological diseases. This has aroused special attention in the discovery of the novel indazoles and their biological activities.

Diagnostic Dilemma: Parasitic Ovarian Fibroma With Degeneration.

An ovarian fibroma is a rare entity and a diagnostic dilemma due to its solid nature and ultrasound findings being similar to a uterine fibroid. An ovarian fibroma, being parasitic, is extremely rare. We report the case of a 35-year-old, multiparous woman who presented with a 'wandering' abdominal mass of six months duration. Clinical examination revealed a 16-week size, solid, firm, well-defined mass in the right lumbar and iliac regions, separate from the uterus on bimanual examination, suggestive of a pedunculated subserous fibroid uterus. Ultrasound abdomen with color Doppler evaluation was suggestive of the non-uterine origin of the tumor, probably a gastrointestinal stromal tumor. In view of the diagnostic dilemma, MRI was done, which showed that the lesion had features characteristic of ovarian fibroma, however, bilateral ovaries were normally visualized. An exploratory laparotomy was performed. There was a solid parasitic tumor adherent to the bladder peritoneum and attached to the right ovary by a thin band, which was excised. Histopathology confirmed ovarian fibroma. To conclude, a parasitic ovarian fibroma is rare and a careful clinical approach with imaging and surgery helps in solving this diagnostic dilemma.

Molecular dynamics simulations of simplified sodium borosilicate glasses: the effect of composition on structure and dynamics.

The fusion of valuable material properties has led to the acceptance of sodium borosilicate (NBS) glasses for nuclear waste immobilization. Although popular, the mechanisms associated with these properties are still only partially discovered and need further exploration. Bearing this in mind, the combination of experiments, molecular dynamics (MD) simulations and the Dell, Yuan and Bray model have been used to understand the role of composition variation for structural and physical aspects of vitrified borosilicate glasses. Experiments have been conducted to evaluate the macroscopic glass parameters of density (ρ), glass transition temperature (Tg) and thermal expansion coefficient (TEC). Experimentally observed trends for ρ, Tg and TEC with composition have been found in good agreement with the MD results. MD studies also provide a microscopic understanding of the glass structure and phenomena associated with the change in the glass composition. A detailed view of local structure and medium-range connectivity for the borosilicate glasses has been explored. Owing to a large B4 population, the results showed the abundant presence of BO4-BO4 connections, we hereby omit the generally accepted "B[4] avoidance rule" for glass. The relative propensity for connecting SiO4/BO3/BO4 structural motifs is in line with the predictions made by the Dell, Yuan and Bray model. Furthermore, the effects of composition on the mechanical integrity of NBS glasses, including the elastic nature, plastic distortion, yielding, breaking stress, and brittle fracture, have been explored by MD simulations. In addition, the glass dynamics have been evaluated by diffusion coefficient and the results suggest that Na+ is likely to be more mobile in the case of NBS1 as compared to NBS2 and NBS3 due to significant disruption in the glass network introduced by a larger amount of Na2O network modifier. Also, the diffusivity was reduced with increasing B2O3 due to the altered role of Na+ ions from network modifiers to charge compensators. The combined study of experiments, MD simulations and the Dell, Yuan and Bray model establish the correlation between the microscopic structure and macroscopic properties of NBS glasses with varied composition, which might be of great scientific use for future glasses in various applications including nuclear waste immobilization.

Study of oral tranexamic acid, topical tranexamic acid, and modified Kligman's regimen in treatment of melasma.

BACKGROUND: Melasma is a pigmentary disorder affecting mainly face . Various treatment modalities available as topicals, superficial chemical peels and lasers but none till date gives promising results, until date quest for the best treatment modality is on. AIM: To study the effect of oral and topical Tranexamic acid (TXA) and modified Kligman's regimen in treatment of melasma. METHOD: Patients having melasma were enrolled after consent for voluntary participation. A detailed history and clinical examination was done. Total 60 patients were enrolled and randomized in three groups, 20 received oral TXA 250 mg twice daily, 20 topical TXA and 20 received modified Kligman's regimen for 8 weeks along with sunscreen MASI(Melasma area severity index) was calculated at baseline, at end of 4 & 8 weeks. MASI score was compared with that at the end of the study. Based on reduction in mean MASI the therapeutic response was graded. Pre and post treatment photographs was also compared. Statistical analysis done by using student square T test , ANOVA And TUKEY test. RESULTS: Reduction in MASI score was observed in all the groups but greater reduction in MASI score with modified Kligman's regimen by 30% followed with oral TXA by 25% reduction and least with topical TXA by 5%. CONCLUSION: Although modified Kligman's regimen is comparatively more efficient but due to its side effects in long term usage oral tranexamic acid could be a promising therapeutic approach for melasma.

Insight into Speciation and Electrochemistry of Uranyl Ions in Deep Eutectic Solvents.

Understanding the speciation of metal ions in heterogeneous hydrogen-bonded deep eutectic solvents (DES) has immense importance for their wide range of applications in green technology, environmental remediation, and nuclear industry. Unfortunately, the fundamental nature of the interaction between DES and actinide ions is almost completely unknown. In the present work, we outline the speciation, solvation mechanism, and redox chemistry of uranyl ion (UO22+) in DES consisting of choline chloride (ChCl) and urea as the hydrogen-bond donor. Electrochemical and spectroscopic techniques along with molecular dynamics (MD) simulations have provided a microscopic insight into the solvation and speciation of the UO22+ ion in DES and also on associated changes in physical composition of the DES. The hydrogen-bonded structure of DES plays an important role in the redox behavior of the UO22+ ion because of its strong complexation with DES components. X-ray absorption spectroscopy and MD simulations showed strong covalent interactions of uranyl ions with the constituents of DES, which led to rearrangement of the hydrogen-bonding network in it without formation of any clusters or aggregations. This, in turn, stabilizes the most unstable pentavalent uranium (UO2+) in the DES. MD analysis also highlights the fact that the number of H-bonds is reduced in the presence of uranyl nitrate irrespective of the presence of water with respect to pristine reline, which suggests high stability of the formed complexed species. The effect of added water up to 20 v/v % on speciation is insignificant for DES, but the presence of water influences the redox chemistry of UO22+ ions considerably. The fundamental findings of the present work would have far reaching consequences on understanding DES, particularly for application in the field of nuclear fuel reprocessing.

Breakdown of continuum model for water transport and desalination through ultrathin graphene nanopores: insights from molecular dynamics simulations.

In the quest for identifying a graphene membrane for efficient water desalination, molecular dynamics simulations were performed for the pressure-driven flow of salty water across a multilayer graphene membrane. Water transport through the graphene membranes was tuned as a function of pore size, external pressure, and salt concentration. The results predicted that water permeability through the graphene channel (width of h = 7 Å) is two orders of magnitude higher than that through the conventional thin film membranes. The breaking of continuum assumption in graphene nanopores was captured by the appearance of a layered water structure and plug-like velocity profiles. Furthermore, the fluidity under nano confinement of graphene was examined in terms of shear viscosity, friction coefficient, and slip length, which were found to depend on the separation of the confining graphene walls and the external pressure. Furthermore, the MD results revealed that the macroscopic water flux through the graphene nanopores can be linked to the microscopic diffusion of water. The calculated viscosity and diffusion coefficient under the graphene pores did not follow the Stokes-Einstein relation, indicating the failure of the hydrodynamic theory. The confined state of water in the graphene pores was also explored via the translational density of states (TDOS) and entropy, which displayed a significant change in the translational entropy with change in the pore size and applied pressure and thus revealed the interconnectivity of the structure, dynamics, thermodynamics, and hydrodynamics of water in the graphene nanopores. Such a linking of the microscopic parameters with the macroscopic profiles provides direct evidence to the experiments of pressure-driven flow through the graphene membranes and might be helpful in examining the performance of graphene membranes for the factors that have large implications on their application in the reverse osmosis (RO) process and other biological channels.

Molecular Dynamics Simulation of Amorphous SiO2, B2O3, Na2O-SiO2, Na2O-B2O3, and Na2O-B2O3-SiO2 Glasses with Variable Compositions and with Cs2O and SrO Dopants.

Selection of suitable glass composition for vitrification of high-level radioactive wastes (HLWs) is one of the major challenges in nuclear waste reprocessing. Atomic and molecular level understanding of various structural, thermodynamical, and dynamical properties of a glass matrix can help in preliminary screening and thus reduce the dependency to some extent on tedious experimental procedures. In that context, extensive molecular dynamics (MD) simulations have been performed to calculate various microscopic properties of the glass matrix. The present article demonstrates that the "Buckingham potential-included long-ranged Coulomb interaction" can be utilized to simulate the glasses of varied compositions. The proposed simulation model has been validated for a wide range of glass compositions: pure glass matrix-SiO2 and B2O3; binary glass mixtures-SiO2-B2O3, Na2O-SiO2, and Na2O-B2O3; ternary glass-Na2O-SiO2-B2O3; and also the Cs2O- and SrO-doped matrix of sodium borosilicate. Most importantly, the MD results have been validated with those of in-house synthesized glasses. The effect of alkali addition on the density and network connectivity of the glass matrix has been explored. The results capture well the boron anomalies for varied concentrations of network formers and network modifiers. The intermediate structural ordering in glasses has been explored by calculating the partial and total structure factors. Further, the characteristic vibration density of states of constituent atoms in the glass matrix is determined. In addition, the glass structures with the addition of dopant oxides Cs2O and SrO have been examined as they are known to be prime heat-generating agents in HLWs. The results establish the structure and dynamics of the doped glass matrix to be a complex nature of the dopant's mass, concentration, charge, and ionic radius. The present MD results might be of great academic and technological significance for further studies in the field of vitrification and prediction of effects associated with the dopant's nature and concentration.

Nanoscopic insights of saline water in carbon nanotube appended filters using molecular dynamics simulations.

Nanotube appended membranes are shown to be very promising due to their ultrafast water transport and very high salt rejection ability. Using classical molecular dynamics, the present study reports the nanoscopic assessment of various molecular events for nanotube-based desalination, which might be useful for nanoscale devices during process operation at the macroscopic scale. The characteristics of water and ion flow are discussed with varied strength of pressure gradient and salt concentration for different scales of confinement. The results revealed that the membranes comprising nanotubes of 1.0-1.1 nm diameter can be optimized for efficient water desalination with more than >95% salt rejection. Furthermore, the anomalies in water flux through nanotubes are linked with the hydration characteristics of ions inside CNTs. The results show the maximum hydration of confined ions inside the nanotubes, which indicated the minimum permeability of water due to freezing effects. Furthermore, the MD results revealed that akin to bulk phases, the mass transport through nanotubes can be linked with the component diffusivity in the medium. It has been demonstrated that not only the diffusivities of water and ions, but even the gradient of water to ion diffusivity might be utilized to predict and explore the experimental observations, which might be helpful in optimizing the operational regime in nanotube-based filtrations. Moreover, the thermodynamic characteristics of the flow are discussed in terms of the entropy of water and ions using the robust two-phase thermodynamic (2PT) method. The results reflect that the entropy of water is linked to the distortion of the hydrogen bond network inside the nanotube confinement, at the nanotube-water interface and at the bulk solution, whereas the entropy of ions seems to be majorly dominated by their oscillation. Also, the interconnection of hydration structure, mass flux and the diffusivity of water and ions along with their thermodynamic origin are discussed.

Structure, Dynamics, and Adsorption of Charged Guest within the Nanocavity of Polymer-Functionalized Neutral Macrocyclic Host.

Host-guest encapsulation has been widely applied for purification and seizing of the metal ions. Macrocyclic crown ethers are one of the most popular hosts in the field of host-guest chemistry, which on functionalization with polymers are employed as an effective adsorbent. In spite of their vast applications, the microscopic information about their sensing mechanism toward cations/molecules is very scarce. Therefore, the present study is focused on the molecular insights of ion-exchange mechanism within the cavity of crown ether-functionalized polymers using molecular dynamics (MD) simulations. This present study investigates the molecular-level events of chloromethylated polystyrene (CMPS) bearing dibenzo-18-crown-6 (DB18C6) in the aqueous and acidic environment, which has been found to be particularly successful in sensing of various alkali and alkali earth metal ions. A strategy has been envisaged to design a crown ether-based functionalized polymeric resin, which exhibits good match of properties with the in-house-synthesized resin. The MD studies well capture the experimentally observed Langmuir-type adsorption isotherms of Li+ ions on crown ether-grafted polymer resins. The presence of acid reduces the adsorption of Li+ ions due to the competition with H3O+ ions. In addition, the results revealed that the "adsorption in crown cavity" follows a dual residence time function. To the best of our knowledge, this is the first report on the adsorption isotherm of functionalized crown ether using MD simulations. The structure and dynamics of binding sites were explored using radial distribution functions and diffusion coefficients. All of these effects have been studied for different Li+-ion concentrations, acid concentrations, and counterions as well as different lengths of polymer chains and degrees of polymerization. Overall, the present study provides insights into and quantitative information about adsorption on the CMPS-DB18C6 resin, which might be useful in myriads of host-guest-based adsorption experiments.