11 research outputs found
Hydroxide Based High Entropy MOF for Oxygen Evolution Reaction
No full textThe energy crisis becomes more prominent in higher altitude countries like Germany, with higher annual energy demand. Thus, the generation of higher energy density fuel like hydrogen from renewable resources become the only way to solve the zero-emission energy system while avoiding the expensive batteries as an energy storage option. Therefore, water electrolysis cells to produce hydrogen and oxygen by storing of solar/wind energy in chemical bonds is a fruitful alternative for renewable and long-term energy generation. Thus, designing inexpensive water-splitting electrocatalyst material becomes a field of research of utmost importance. High entropy metal hydroxide organic frameworks (HE-MHOFs) are composed of high entropy hydroxide layer inside MOFs, resulting in a high degree of structural complexity and diversity than conventional MOFs. The concept of ‘high entropy’ refers to multiple types of metal ions (Metal = TM) in a near equimolar ratio in the same framework, creating a high degree of disorder and many possible structural configurations. Here, the HE-MHOF successfully synthesized by a conventional solvothermal process, crystallizes in the single phase with significant lattice distortion. A special-quasi-random (SQS) structure was simulated with equimolar compositions (~20% TM = Mn, Co, Ni, Cu and Zn) and a comparison was made with the ICP-AES (inductively coupled plasma atomic emission spectroscopy), XANES (X-ray absorption near edge structure) and XAFS (X-ray absorption fine structure) observations. Further, the elemental mapping (Energy dispersive Spectroscopy) of HE-MHOF shows the presence of all five different metals in the same crystallite to substantiate the ‘high entropy’ state of the MOF. The HE-MHOF offers improved thermal stability than mono-metallic MHOF and exhibit unique properties compared to traditional monometallic (Ni2+) MOF variants. Firstly, to elucidate the effect of the multimetallic system on the catalytic performance, we have performed density functional theory (DFT) calculations to investigate pre-redox cycles involved in the catalytic activation of HE (and Ni)-MOFs. HE-MHOF is further investigated as an electrocatalyst for oxygen evolution reaction (OER) due to its special high entropy hydroxide layered structure and electronic properties. Our DFT results have examined the traditional proton-coupled electron transfer (PCET) steps involving the single transition-metal site. The scrutiny of d-band centers and their behaviour in catalytic upgradation is investigated with density of states (DOS) analysis. It exhibits outstanding performance towards oxygen evolution reaction (OER) comparable to the experimental findings, which is also comparable to state-of-the-art OER catalysts based on precious metals such as iridium oxide and platinum carbon. We have considered different electrolyte solutions to elucidate the fast kinetics oxygen evolution reaction in the presence of various external nucleophilic anions. In hydroxyl-based MOFs, electrolytes' influence can substantially enhance catalytic activities. Here, with the help of DFT simulations, we have investigated the effect of the nucleophilicity of anion on each elementary reaction involved in the PCET mechanism of OER
A COMPARATIVE STUDY TO EVALUATE THE CLINICAL OUTCOME OF CONJUNCTIVAL LIMBAL AUTOGRAFT AND AMNIOTIC MEMBRANE TRANSPLANT FOR THE TREATMENT OF PRIMARY PTERYGIUM
No full textObjective: The aim of the study was to assess the safety and effectiveness of the conjunctival limbal autograft (CLAG) and amniotic membrane transplantation (AMT).
Methods: After a full pre-operative assessment 100 patients with primary pterygium attending the ophthalmology outpatient department of a teaching hospital in Eastern India, fulfilling the inclusion and exclusion criteria were selected for our study. The patients were explained the procedure of the study and possible outcomes. They were divided into two groups. Group A: Where 10-0 nylon was to be used for CLAG after pterygium excision. Group B: Where 10-0 nylon was to be used for AMT after pterygium excision.
Results: There was marked improvement in vision postoperatively more in the AMT group than CLAG. In the AMT group: 34% had a visual acuity of LogMAR 0.00, 30% had LogMAR 0.12, 12% had LogMAR 0.18, and 24% had LogMAR 0.30 after the surgery. In the CLAG group: 52% had a visual acuity of LogMAR, 20% had LogMAR 0.12, 22% had LogMAR 0.18, and 6% had LogMAR 0.30 after the surgery. Graft and suture-related complications were more in the CLAG group than in the amniotic membrane (AM) graft group.
Conclusion: In the present study, The CLAG group was found to be associated with more discomfort, and more post-operative complications than AMT. AM may provide a basement membrane rich in various growth factors and matrix proteins, which promotes epithelial cell migration, adhesion, and differentiation. It is also believed to have anti-inflammatory and antifibrotic effects and exerts anti-scarring effects through the transforming growth factor-β pathway. AMT may be a superior treatment in primary pterygium due to lower recurrence rate, shorter surgical times, and better visual and cosmetic outcomes
A STUDY ON ASSOCIATION OF SYSTOLIC BLOOD PRESSURE, DIASTOLIC BLOOD PRESSURE, AND PULSE PRESSURE WITH INTRAOCULAR PRESSURE IN RELATION TO PRIMARY OPEN-ANGLE GLAUCOMA
No full textObjective: This study aims to probe the relationship among pulse pressure (PP), systolic blood pressure (SBP) and diastolic blood pressure (DBP), and the intraocular pressure (IOP) in normal persons and primary open-angle glaucoma (POAG) patients. Design: This was an institution-based observational study.
Methods: This study was conducted on 240 patients attending the ophthalmology department and glaucoma clinic of a tertiary hospital. Included subjects were asked about their ocular and systemic problems and undergone detailed examination of eyelids, conjunctiva, cornea, anterior chamber by slit lamp, visual acuity, refraction, and fundus examination. IOP was measured by Goldmann applanation tonometer. Blood pressure was measured by sphygmomanometer.
Results: In this study, we found that SBP, DBP, PP, and IOP – both eyes were found to be higher in subjects with POAG than normal control subjects. Among these, differences in mean SBP, DBP, and IOP – both eyes between subjects with POAG and normal subjects were statistically significant. IOP was found to be positively correlated with SBP, DBP, and PP both in subjects with POAG as well as in normal subjects.
Conclusion: Although involving a limited number of eyes, the key findings of the study suggest that IOP is positively correlated with PP, SBP, and DBP. This opens up the possibility of early detection of glaucoma patients with raised PP, SBP, and DBP
Probing the Role of Anions in Influencing the Structure, Stability, and Properties in Neutral N‑Donor Linker Based Metal–Organic Frameworks
No full textThe
understanding of structure–property and structure–stability
correlation has become an important facet of material development
in the domain of metal–organic frameworks (MOFs). Owing to
the paucity of stable compounds, the progress of constructing MOFs
out of neutral linkers that exhibit remarkable promise has largely
been stalled. To understand the influence of anions in affording structure
features, properties, and stability in such MOFs, a series of MOFs
constructed from same metal cation and ligand have been synthesized
and examined. Further ascribing a structure–property correlation,
the stable MOFs obtained in this work have been applied for sensing
and capture of the radioactive pertechnetate anion TcO4–, via surrogate anions MnO4– and ReO4–, and capture of the greenhouse
gas CO2. Notably, the sensing of such toxic anions has
been rarely been explored using porous crystalline solids
Multifunctional Behavior of Sulfonate-Based Hydrolytically Stable Microporous Metal–Organic Frameworks
No full textAn
isostructural pair of extremely rare, permanently microporous
sulfonate-based metal–organic frameworks (MOFs) having a novel
topology has been reported here by integration of rationally chosen
building units. The compounds bear polar sites in the pore surfaces
and exhibit selective adsorption of CO2, which features
among the highest reported uptakes in the domain of organosulfonate-based
MOFs. The compounds also exhibit multifunctionality for C6-cyclic hydrocarbon separation and selective detection of neurotransmitter
nitric oxide. Such multifunctional behavior on the basis of permanent
porosity has been rarely observed for sulfonate-based MOFs. The efficacy
of the synthesis approach is further highlighted by the resistance
over a wide pH range and promising feasibility of reticular chemistry
in porous organosulfonate-based systems
Multifunctional Behavior of Sulfonate-Based Hydrolytically Stable Microporous Metal–Organic Frameworks
No full textAn
isostructural pair of extremely rare, permanently microporous
sulfonate-based metal–organic frameworks (MOFs) having a novel
topology has been reported here by integration of rationally chosen
building units. The compounds bear polar sites in the pore surfaces
and exhibit selective adsorption of CO2, which features
among the highest reported uptakes in the domain of organosulfonate-based
MOFs. The compounds also exhibit multifunctionality for C6-cyclic hydrocarbon separation and selective detection of neurotransmitter
nitric oxide. Such multifunctional behavior on the basis of permanent
porosity has been rarely observed for sulfonate-based MOFs. The efficacy
of the synthesis approach is further highlighted by the resistance
over a wide pH range and promising feasibility of reticular chemistry
in porous organosulfonate-based systems
Multifunctional Behavior of Sulfonate-Based Hydrolytically Stable Microporous Metal–Organic Frameworks
No full textAn
isostructural pair of extremely rare, permanently microporous
sulfonate-based metal–organic frameworks (MOFs) having a novel
topology has been reported here by integration of rationally chosen
building units. The compounds bear polar sites in the pore surfaces
and exhibit selective adsorption of CO2, which features
among the highest reported uptakes in the domain of organosulfonate-based
MOFs. The compounds also exhibit multifunctionality for C6-cyclic hydrocarbon separation and selective detection of neurotransmitter
nitric oxide. Such multifunctional behavior on the basis of permanent
porosity has been rarely observed for sulfonate-based MOFs. The efficacy
of the synthesis approach is further highlighted by the resistance
over a wide pH range and promising feasibility of reticular chemistry
in porous organosulfonate-based systems
Zirconium fluoride-supported high-entropy fluoride: a catalyst for enhanced oxygen evolution reaction
No full textExtended hydrogen initiatives promote the urgency of research on water splitting technologies and, therein, oxygen evolution reaction catalysts being developed. A route to access a ZrF4 supported high-entropy fluoride catalyst using a facile sol–gel route is presented. The high-entropy character of the catalyst was confirmed by scanning transmission electron microscopy and energy dispersive X-ray spectroscopy (STEM-EDX) as well as inductively coupled plasma-mass spectrometry (ICP-MS). Additional investigations on the local structure were performed using extended X-ray absorption fine structure spectroscopy (EXAFS) and pair distribution function (PDF) analysis. The catalyst shows significant potential for oxygen evolution reaction (OER) in alkaline media with a current density of 100 mA cm−2 at approximately 1.60 V, thus outperforming benchmark materials such as IrO2, despite a significant reduction in electrochemical mass loading. A potential mechanism is suggested based on free energy calculation using DFT calculations
Zirconium fluoride-supported high-entropy fluoride: a catalyst for enhanced oxygen evolution reaction
No full textExtended hydrogen initiatives promote the urgency of research on water splitting technologies and, therein, oxygen evolution reaction catalysts being developed. A route to access a ZrF4 supported high-entropy fluoride catalyst using a facile sol–gel route is presented. The high-entropy character of the catalyst was confirmed by scanning transmission electron microscopy and energy dispersive X-ray spectroscopy (STEM-EDX) as well as inductively coupled plasma-mass spectrometry (ICP-MS). Additional investigations on the local structure were performed using extended X-ray absorption fine structure spectroscopy (EXAFS) and pair distribution function (PDF) analysis. The catalyst shows significant potential for oxygen evolution reaction (OER) in alkaline media with a current density of 100 mA cm−2 at approximately 1.60 V, thus outperforming benchmark materials such as IrO2, despite a significant reduction in electrochemical mass loading. A potential mechanism is suggested based on free energy calculation using DFT calculations.Deutsche Forschungsgemeinschaft 10.13039/501100001659Peer Reviewe
