Photoelectrochemical Studies on Non-Noble Metal Based Catalysts towards Tandem Solar Water Splitting

Photoelectrochemical (PEC) water splitting makes direct use of solar energy incident on semiconductor photoelectrodes, and it is a convenient, economic option to produce high purity hydrogen at low temperatures. The use of multiple light absorbers can increase overall solar energy utilization and provide a solution to the trade-off between overall band gap and band edge positioning of photoelectrodes specific to solar water oxidation and water reduction. The study of non-noble metal based catalysts for hydrogen evolution reaction (HER) and oxygen evolution reactions (OER) are essential for economic practical commercialization of photo-electrolyzers. This dissertation focuses on the use of a variety of non-noble transition metal chalcogenide based heterogeneous co-catalysts, and solution based water redox catalysts immobilized in polyoxometalate (POM) ensembles for water splitting in single and multiple absorber based systems. With a brief discussion on background and literature review in Chapter I, Chapter II reports PEC studies on TiO2 photoanode in contact with solution-phase nickel-POM co-catalyst viz. K10H2[Ni5(OH)6(OH2)3(Si2W18O66)]•34H2O (Ni5-POM) for water oxidation, whereas Chapter III presents PEC studies on CuxSe photocathode using cobalt-POM co-catalyst viz. [Co9(OH)3(H2O)6(HPO4)2(PW9O34)3]16-(Co9-POM) for water reduction. Chapters IV focuses on the use of electrodeposited transition metal selenide based co-catalysts for solar water reduction with Cu2O photocathodes, and Chapter V demonstrates the results of solar water oxidation using transition metal phosphide and selenide based co-catalysts electrodeposited on Fe2O3 and BiVO4 photoanodes. UV-Vis spectroscopy, scanning electron microscopy, and energy dispersive energy diffraction (EDX) were used for characterization of photoelectrodes and heterogeneous co-catalysts. Synthesized metal-POMs were characterized using FT-IR and mass spectrometry. PEC measurements conducted under simulated solar irradiation provided evidence of significantly increased photocurrents, lowered onset potential and increased electron-hole separation in the presence of co-catalysts. Production of oxygen during solar water oxidation was verified with a dissolved oxygen sensor, and the stability of photoelectrodes were examined with multi-potential step experiments. An approximate 10 times increase in photocurrent (i.e., from ~0.008 to 0.08 mA/cm2) was observed under zero biased water splitting at TiO­2 photoanodes upon the addition of Ni5-POM co-catalyst to the electrolyte solution. A maximum water reduction photocurrent of ~ 2 mA/cm2 at -0.45 V vs Ag/AgCl was observed from Cu2O photocathodes with electrodeposited MnSe as water reduction co-catalyst. In Chapter VI, multiple-absorber configurations based on the above studied metal oxide photoanode/photocathode and a commercially available amorphous Si triple junction (3 jn Si) photoanode with Ni- or Co-POM solution-phase co-catalysts or heterogeneous transition metal chalcogenide co-catalysts are presented. The maximum zero bias photocurrents of -3.50 and -0.60 mA/cm2 were observed from the tandem cells of 3 jn Si/Ni5-POM [photoanode] : FTO/Cu2O-MnSe [photocathode] and FTO/TiO2/Ni5-POM [photoanode] : FTO/Cu2O-MnSe [photocathode] water splitting systems, respectively. As of date, there have been limited studies on the use of non-noble metal POMs and chalcogenide based catalysts for PEC water splitting, and the large unbiased photocurrents obtained from this dissertation with respective to those shown in recent literature are clearly promising. Hence, the present studies provide a useful insight into the investigation of more efficient and commercially viable tandem water splitting systems in the future as discussed in Chapter VII

Formulation and characterization of an apigenin-phospholipid phytosome (APLC) for improved solubility, in vivo bioavailability, and antioxidant potential

The apigenin-phospholipid phytosome (APLC) was developed to improve the aqueous solubility, dissolution, in vivo bioavailability, and antioxidant activity of apigenin. The APLC synthesis was guided by a full factorial design strategy, incorporating specific formulation and process variables to deliver an optimized product. The design-optimized formulation was assayed for aqueous solubility, in vitro dissolution, pharmacokinetics, and antioxidant activity. The pharmacological evaluation was carried out by assessing its effects on carbon tetrachloride-induced elevation of liver function marker enzymes in a rat model. The antioxidant activity was assessed by studying its effects on the liver antioxidant marker enzymes. The developed model was validated using the design-optimized levels of formulation and process variables. The physical-chemical characterization confirmed the formation of phytosomes. The optimized formulation demonstrated over 36-fold higher aqueous solubility of apigenin, compared to that of pure apigenin. The formulation also exhibited a significantly higher rate and extent of apigenin release in dissolution studies. The pharmacokinetic analysis revealed a significant enhancement in the oral bioavailability of apigenin from the prepared formulation, compared to pure apigenin. The liver function tests indicated that the prepared phytosome showed a significantly improved restoration of all carbon tetrachloride-elevated rat liver function marker enzymes. The prepared formulation also exhibited antioxidant potential by significantly increasing the levels of glutathione, superoxide dismutase, catalase, and decreasing the levels of lipid peroxidase. The study shows that phospholipid-based phytosome is a promising and viable strategy for improving the delivery of apigenin and similar phytoconstituents with low aqueous solubility

Drug-Phospholipid Complex-loaded Matrix Film Formulation for the Enhanced Transdermal Delivery of Quercetin

A novel quercetin-phospholipid-complex(QPLC)-loaded matrix film for improved transdermal delivery of quercetin was developed. The QPLC formulation, prepared using a solvent-evaporation method, was optimized using a central-composite design. The optimized QPLC formulation was characterized by particle size and zeta potential analysis, thermal analysis, Fourier transform infrared spectroscopy (FTIR), and proton nuclear magnetic resonance spectroscopy (1H-NMR). QPLC formulation was functionally evaluated for solubility and in vitro dissolution of quercetin. Matrix films of pure quercetin (Q-MF)or QPLC QPLC-MF) were prepared using a solvent casting method. The prepared Q-MF and QPLC-MF were characterized for weight uniformity, folding endurance, moisture content, and moisture uptake. The films were also functionally characterized for in vitro diffusion of quercetin through a dialysis membrane and ex vivo permeability of quercetin across rat skin. Finally, the anti-inflammatory activity of the films was evaluated on carrageenan-induced paw edema in Wistar albino rats. The experimental design identified the optimal formulation and process variables for the preparation of QPLC. The validation of the obtained model using these values confirmed the suitability and robustness of the model. The physical-chemical characterization of the prepared QPLC supported the formation of a stable complex. The solubility analysis of QPLC showed a 22-fold increase in quercetin aqueous solubility, compared to pure quercetin. The dissolution results exhibited a significantly higher rate and extent of quercetin dissolution from QPLC compared to that of pure quercetin. The permeability of quercetin from Q-MF and QPLC-MF across rat skin mirrored those obtained from the dissolution studies. Topical application of QPLC-MF exhibited a significant (p\u3c0.05) inhibition of carrageenan-induced paw edema in rats compared to that of Q-MF. This study provides a promising combination approach, i.e., phospholipid-based complexation and transdermal film formulation for improved transdermal delivery of quercetin and similar pharmacologically active phytoconstituents

Kaempferol-Phospholipid Complex: Formulation, and Evaluation of Improved Solubility, In Vivo Bioavailability, and Antioxidant Potential of Kaempferol

The current work describes the formulation and evaluation of a phospholipid complex of kaempferol toenhance the latter’s aqueous solubility, in vitro dissolution rate, in vivo antioxidant and hepatoprotectiveactivities, and oral bioavailability. The kaempferol-phospholipid complex was synthesized using a freeze-drying method with the formulation being optimized using a full factorial design (32) approach. The resultsinclude the validation of the mathematical model in order to ascertain the role of specific formulation andprocess variables that contribute favorably to the formulation’s development. The final product wascharacterized and confirmed by Differential Scanning Calorimetry (DSC), Fourier Transform InfraredSpectroscopy (FTIR), Proton Nuclear Magnetic Resonance Spectroscopy (1H-NMR), and Powder X-rayDiffraction (PXRD) analysis. The aqueous solubility and the in vitro dissolution rate were enhanced comparedto that of pure kaempferol. The in vivo antioxidant properties of the kaempferol-phospholipid complex wereevaluated by measuring its impact on carbon tetrachloride (CCl4)-intoxicated rats. The optimizedphospholipid complex improved the liver function test parameters to a significant level by restoration of allelevated liver marker enzymes in CCl4-intoxicated rats. The complex also enhanced the in vivo antioxidantpotential by increasing levels of GSH (reduced glutathione), SOD (superoxide dismutase), catalase anddecreasing lipid peroxidation, compared to that of pure kaempferol. The final optimized phospholipidcomplex also demonstrated a significant improvement in oral bioavailability demonstrated by improvementsto key pharmacokinetic parameters, compared to that of pure kaempferol

A Comparative Study of Rapid Trypsinogen 2 Strip Test Versus Serum Amylase and Serum Lipase in Diagnosis of Acute Pancreatitis in A Tertiary Care Hospital, Salem

Aims & Objectives:  To assess the diagnostic usefulness of a quick urine trypsinogen 2 strip test to blood amylase and lipase in instances with acute pancreatitis. Methods: Patients who may have an acute pancreatitis diagnosis and have recent onset of stomach pain are included. In these cases, serum samples of amylase and lipase are sent before a urine sample is examined using a dipstick test for urinary trypsinogen-2. Fifty-two participants were included in the research. Ultrasound and CECT abdomen were used to monitor patients and confirm the diagnosis. A number of metrics were computed and compared, including sensitivity, specificity, PPV, NPV, and accuracy. Result: During June 2022 and June 2023, 52 consecutive patients complaining of upper abdominal discomfort were included in the research. Acute pancreatitis was the diagnosed diagnosis in 45 of the 52 patients, whereas other causes of abdominal discomfort were present in 7 individuals. The pee dipstick test was positive in 44 of the 45 instances, but was negative in 5 of the 7 cases when the discomfort in the abdomen was caused by anything other than a urinary tract infection. It was shown to have a 97.78 percent sensitivity, a 71.43 percent specificity, and a 94.23 % accuracy. Conclusion: Acute pancreatitis may be diagnosed quickly and easily with a fast urine trypsinogen-2 test. This study shows that the dipstick test is just as accurate as the gold standard procedures and may be used alternately with them

An Unusual Presentation of “Two-Thirds Tumor” in the Mandible – A Diagnostic Quandary with a Review of the Literature

An adenomatoid odontogenic tumor (AOT) is an uncommon benign tumor of the oral cavity commonly found in the maxillary anterior region and is associated with impacted canines in young females. It rarely occurs in the mandibular region with no impacted or missing teeth. A 21-year-old female reported to the clinic with swelling on the right side of the face for the past six months with no history of pain. Radiographic features such as unilocular radiolucency with thinning of the cortical borders and considerable buccal cortical expansion, as well as some evidence of radiopaque specks were noted. Histopathological examination revealed cells with hyperchromatic nuclei, rosette-like structures with focal areas of calcified mass, and concentric rings resembling Liesegang rings, suggestive of AOT. The tumor was treated surgically by enucleation and cauterization. Although follicular type is a common variant, the tumor presented in this case was of extrafollicular type noted in the mandibular canine and premolar regions of a young female patient with no related impacted tooth

Formulation and Characterization of the Improved Solubility, In Vivo Bioavailability and Antioxidant Activity of Apigenin-Phospholipid Complex (APLC)

In the present study a phospholipid based complex of apigenin (APLC) was prepared with a goal of improving its aqueous solubility, dissolution, in vivobioavailability, and antioxidant activity

Dew: Transparent Constant-sized zkSNARKs

We construct polynomial commitment schemes with constant sized evaluation proofs and logarithmic verification time in the transparent setting. To the best of our knowledge, this is the first result achieving this combination of properties. Our starting point is a transparent inner product commitment scheme with constant-sized proofs and linear verification. We build on this to construct a polynomial commitment scheme with constant size evaluation proofs and logarithmic (in the degree of the polynomial) verification time. Our constructions make use of groups of unknown order instantiated by class groups. We prove security of our construction in the Generic Group Model (GGM). Using our polynomial commitment scheme to compile an information-theoretic proof system yields Dew -- a transparent and constant-sized zkSNARK (Zero-knowledge Succinct Non-interactive ARguments of Knowledge) with logarithmic verification. Finally, we show how to recover the result of DARK (Bünz et al., Eurocrypt 2020). DARK presented a succinct transparent polynomial commitment scheme with logarithmic proof size and verification. However, it was recently discovered to have a gap in its security proof (Block et al, CRYPTO 2021). We recover its extractability based on our polynomial commitment construction, thus obtaining a transparent polynomial commitment scheme with logarithmic proof size and verification under the same assumptions as DARK, but with a prover time that is quadratic