Employing 1H NMR Research Articles

Preparation of Environmentally Friendly Anticorrosive Coatings with Aniline Trimer-Modified Waterborne Polyurethane

Eco-friendly waterborne coatings frequently exhibit poor corrosion resistance, high solvent content, and extended curing times, attributed to the excessive employment of hydrophilic groups and petroleum-derived polyols. In this work, aniline trimer (ACAT) and polyethylene glycol (PEG) were used as chain extenders. E-44 epoxy resin was subsequently utilized to modify the system and an aniline trimer-modified waterborne polyurethane (AT-WPU) dispersion was prepared and characterized. The chemical structure of the synthesized ACAT was characterized employing 1H NMR, ESI-MS, and FTIR spectroscopy. The structure and coating performance of the AT-WPU dispersion were investigated utilizing FTIR, particle size analysis, thermogravimetric analysis, DSC, TEM, SEM, and electrochemical corrosion testing. The results demonstrate that the aniline trimer-modified waterborne polyurethane dispersion was successfully synthesized. Additionally, the DSC analysis results and thermogravimetric graphs indicate that the glass transition temperature and thermal stability of the coatings increased with the addition of aniline trimer. As the aniline trimer content increased, the hardness and adhesion of the coatings were significantly enhanced. In the electrochemical corrosion assessment, the corrosion current density of AT-WPU-3 attained 7.245 × 10−9 A·cm−2, and the corrosion rate was as low as 0.08 μm·Y−1, indicating excellent corrosion resistance. The present study provides promising practical applications in the domain of metal material protection.

Enhancing protein extraction from Pleurotus ostreatus using synergistic pH-shifting and ultrasonic technology: Optimization via RSM and 1H NMR-based metabolomic profiling

This study explores the impact of ultrasound and pH-shifting on protein extraction from P. ostreatus, employing 1H NMR techniques to monitor metabolites and elucidate the extraction mechanism. The NMR-based metabolic analysis demonstrated that extended sonication time significantly boosted amino acid release. To optimize conditions for maximizing protein yield, response surface methodology was performed. This research aims to enhance protein extraction from P. ostreatus by analyzing the interplay between ultrasound treatment and pH-shifting. The results indicate that the synergistic use of pH-shifting and ultrasound-assisted extraction (UAE) significantly improves protein yield. The amino acid profile of the protein concentrates revealed a high content of essential amino acids, with tryptophan identified as the limiting amino acid. Additionally, the combined extraction method enhanced the emulsifying properties and foaming stability of the protein concentrates. Thus, combining pH-shifting and UAE is a promising technique for extracting high-quality protein from P. ostreatus, enhancing functional properties and efficiency.

Synthesis, Anticancer Evaluation and Molecular Docking Studies of 1-(2-Fluorobenzyl)piperazine Triazoles: A Novel Breast Cancer Cell Inhibitors

New series of 1-(2-fluorobenzyl)piperazine triazoles 7(a-k) have been synthesized and evaluated for anticancer activity. The molecular structures of all the compounds were established by employing 1H NMR, 13C NMR and mass spectral analysis. In vitro anticancer activity was evaluated using MTT assay against MCF7 breast cancer cell line. Compounds 7i and 7j bearing 4-fluorophenyl and 2-fluorophenyl pendant from triazole substituent phenyl ring exhibited the highest anticancer efficacy with IC50 values of 12.09 µg/mL and 15.12 µg/mL, respectively. A molecular docking study conducted on human HER2 complexed with hercepatin fab was acquired from Protein Data Bank (PDB ID: 1N8Z). Molecular docking studies demonstrated Leu443, Gly442 and Leu27 as key residues interacting with active compounds.

Biodynamic, organic and integrated agriculture effects on cv. Italia table grapes juice, over a 3-year period experiment: an 1H NMR spectroscopy-based metabolomics study

BackgroundThe new trend demanding for “natural” agri-food products has encouraged the application of more sustainable and eco-friendly farming methods, which limit or avoid the use of synthetic chemicals. This approach is increasing in viticulture, one of the sectors with the highest commercial value since grapes and derived products are largely consumed foodstuffs, with appreciated nutritional and sensory features. In this work, 1H Nuclear Magnetic Resonance spectroscopy (1H NMR) was applied for the metabolic profiling of cv. Italia table grapes samples, from the same origin area, cultivated with different treatments (biodynamic, organic and integrated) and collected in three subsequent vintages. Multivariate statistical analysis was performed on NMR-data with the aim of comprehensively researching the possible influences on metabolites due to the use of diverse agricultural practices.ResultsBoth inter-annual variability (2020, 2021 and 2022 vintages) and different vineyard treatments (biodynamic, organic and integrated) resulted as significant drivers for samples differentiation in the preliminary unsupervised analysis of the (1H NMR spectra derived) metabolic profile data. Nevertheless, supervised data analyses showed that inter-vineyards variability, due to application of diverse farming methods, had a comparable discriminating effect with respect to harvesting years. Ethanol, sugars (as α-/β-glucose), organic acids (as malate) and amino acids (as arginine, leucine, glutamine) resulted the most viticultural practices-dependent metabolites. Interestingly, results from pairwise comparisons between treatments indicated the biodynamic samples with respect to the organic ones as the best-observed differentiation. This was followed by the biodynamic vs integrated and organic vs integrated samples comparisons, in decreasing discrimination order, as confirmed by the descriptiveness and predictive ability parameters of the corresponding pairwise OPLS-DA models.ConclusionsResults highlighted that metabolites’ composition in cv. Italia table grapes juice is significantly affected by the use of different kinds of vineyard managements (biodynamic, organic and integrated, here investigated). Metabolomics study, here employing 1H NMR spectroscopy combined with multivariate statistical analysis, offers powerful tools to elucidate the metabolic differences among classes of samples.Graphical

Metabolomic Profiling of Second-Trimester Amniotic Fluid for Predicting Preterm Delivery: Insights from NMR Analysis.

Preterm delivery (PTD) is a notable pregnancy complication, affecting one out of every ten births. This study set out to investigate whether analyzing the metabolic composition of amniotic fluid (AF) collected from pregnant women during the second trimester of pregnancy could offer valuable insights into prematurity. The research employed 1H-NMR metabolomics to examine AF samples obtained from 17 women who gave birth prematurely (between 29+0 and 36+5 weeks of gestation) and 43 women who delivered at full term. The application of multivariate analysis revealed metabolites (dimethylglycine, glucose, myo-inositol, and succinate) that can serve as possible biomarkers for the prognosis and early diagnosis of preterm delivery. Additionally, pathway analysis unveiled the most critical metabolic pathways relevant to our research hypothesis. In summary, these findings suggest that the metabolic composition of AF in the second trimester can be a potential indicator for identifying biomarkers associated with the risk of PTD.

1H NMR Reveals Dynamic Changes of Primary Metabolites in Purple Passion Fruit (Passiflora edulis Sims) Juice during Maturation and Ripening

Passion fruit (Passiflora edulis Sims) is a tropical fruit that shows an increasing demand from global fresh fruit industries. The fruit is known to have climacteric properties that allow it to achieve ripening during distribution and transportation. However, the metabolic alterations that occur during ripening are poorly understood. Thus, this study was conducted to analyze the metabolites in passion fruit juice at different harvesting stages (35, 42, 49, 56 and 63 days after anthesis), employing 1H NMR spectroscopy combined with chemometric analysis. A total of 30 metabolites were successfully identified using 1H NMR, the majority of which belong to primary metabolites, consisting of 14 amino acids, 7 sugars and 6 organic acids. Nevertheless, only three secondary metabolites were detected. Analyzing the metabolites using multivariate analysis reveals 13 of the metabolites were highly influential metabolites. These primary metabolites play essential roles in the maturation and ripening of fruit. Glycolysis, the tricarboxylic acid (TCA) cycle and the shikimate pathway were differentially regulated during maturation and ripening of passion fruit. Profiling the metabolome of fruit during maturation and ripening reveals that all metabolites are interconnected with each other to cause maturation and ripening in passion fruit. This work will enhance the knowledge of physiological changes in purple passion fruit during maturation and ripening.

Properties of a furan ring-opening reaction in aqueous micellar solutions for selective sensing of mesalazine

A novel and efficient non-azo formation based method was developed for trace sensing of mesalazine (MES), a pharmaceutical aromatic amine. MES was simply coupled with a Meldrum’s activated furan (MAF) reagent via a furan ring opening reaction to form a colored product. The intense purple colored solution was detected at 575 nm. The reaction of MES with MAF was monitored by employing 1H NMR spectroscopy and mass spectrometry. In addition, density functional theory (DFT) was applied to optimize the structure of the colored product and its λmax (the wavelength of maximum absorbance) in dimethyl sulfoxide and water. The colored product was considered in three possible structures, and the most possible structures in dimethyl sulfoxide and in water were identified by employing the DFT calculations. Both of the most possible structures indicated only a local excitation in their λmax and no charge transfer was observed. However, one of the structures in dimethyl sulfoxide presented charge transfer properties occurring through NCCC moiety. A univariate optimization method was also used to attain the optimum condition for analysis. In addition, the dependence of the analytical response on the three main affecting parameters (reaction time (X1), Triton X-100 concentration (X2) and MAF concentration (X3)) was identified by employing a central composite design (CCD) approach. The CCD study showed that the analytical response depends complexly on the parameters. Beer’s law was obeyed within the range of 0.06–9.30 μg mL−1 of MES (155 fold linearity) at 575 nm, under the optimum condition introduced by the CCD approach. Also, the limit of detection was obtained 0.04 μg mL−1 of MES. The method showed precision (as relative standard deviation) and accuracy (as recovery) within the ranges of 0.6–3.2 % and 96.3–100.8%, respectively. Various organic and inorganic species, amino-pharmaceuticals, and amino acids were tested to evaluate the selectivity of the method. The selectivity of the analytical method was satisfactory. The method was successfully applied for detection of MES in various water matrices and pharmaceutical tablets.

Adaptive Chirality of an Achiral Cage: Chirality Transfer, Induction, and Circularly Polarized Luminescence through Aqueous Host–Guest Complexation

Chirality transfer, induction, and circularly polarized luminescence (CPL) using supramolecular hosts, such as macrocycles and cages, have been explored for wide-ranging applications in chiral reco...

Novel rhodamine based chemosensor for detection of Hg2+: Nanomolar detection, real water sample analysis, and intracellular cell imaging

A novel fluorescent chemosensor PS founded on rhodamine 6G for Hg2+ has been synthesized and authenticated by employing 1H NMR, 13C NMR, and LC–MS skills. The fluorescent chemosensor displays an intense selectivity and sensitivity for Hg2+ over additional metal ions explored in the combined organic aqueous phase. A strong fluorescence enhancement was detected after the addition of Hg2+, which was accompanied by ring-opening of a rhodamine spiro-cyclic structure. The stoichiometric ratio of the PS-Hg2+ complexes was determined to be 1:1 according to Job’s plot and 1H NMR experiment. The binding constant and limit of detection (LOD) for PS-Hg2+ complexation is estimated to be 6 × 104 M−1 and 3.0375 × 10-8 M (30.37 nM), respectively. The extreme fluorescent enhancement caused by Hg2+ binding in chemosensor PS occurred at a pH range of 6−8. Owing to practical application, the Hg2+ metal ion was efficiently determined using a spike and recovery approach from real water samples. Additionally, the probe PS was further used in the cell imaging experiment for the detection of the Hg2+ intracellularly using MDA-MB-231 and A375 breast cancer cells by MTT assay method with low cytotoxicity.

Lignin-methyl methacrylate polymer as a hydrophobic multifunctional material

In this work, the modification of lignin (KL) with methyl methacrylate (MMA) is presented via free-radical polymerization in the presence of potassium persulfate as an initiator. One-step purification of the reaction products was also attested for generating KL-MMA with 95 wt% yield and 85 wt% MMA conversion. The characteristics of KL-MMA were studied comprehensively employing 1H NMR, 31P-NMR, 13C-NMR, SEM, FTIR, and GPC. KL-MMA demonstrated significantly higher thermal stability and UV absorption compared with unmodified KL and PMMA homopolymer. The hydrophobicity of lignin derivatives was substantially improved via reacting with acrylate monomer (a contact angle change from 25° for KL to 88° for KL-MMA). The performance of KL-MMA as an adsorbent for humic acid (HA) was also evaluated in detail by means of a Quartz crystal microbalance with dissipation (QCM-D). The results confirmed the superior adsorption performance of KL-MMA to that of KL and PMMA for HA. The modified lignin polymer possessed a multitude of excellent features including remarkable hydrophobic properties and adsorption capacity. The product offers a wide range of applications possibly in food packaging and water purification systems.

The Influence of the Ligand in the Iridium Mediated Electrocatalyic Water Oxidation.

Electrochemical water oxidation is the bottleneck of electrolyzers as even the best catalysts, iridium and ruthenium oxides, have to operate at significant overpotentials. Previously, the position of a hydroxyl on a series of hydroxylpicolinate ligands was found to significantly influence the activity of molecular iridium catalysts in sacrificial oxidant driven water oxidation. In this study, these catalysts were tested under electrochemical conditions and benchmarked to several other known molecular iridium catalysts under the exact same conditions. This allowed us to compare these catalysts directly and observe whether structure–activity relationships would prevail under electrochemical conditions. Using both electrochemical quartz crystal microbalance experiments and X-ray photoelectron spectroscopy, we found that all studied iridium complexes form an iridium deposit on the electrode with binding energies ranging from 62.4 to 62.7 eV for the major Ir 4f7/2 species. These do not match the binding energies found for the parent complexes, which have a broader binding energy range from 61.7 to 62.7 eV and show a clear relationship to the electronegativity induced by the ligands. Moreover, all catalysts performed the electrochemical water oxidation in the same order of magnitude as the maximum currents ranged from 0.2 to 0.6 mA cm–2 once more without clear structure–activity relationships. In addition, by employing 1H NMR spectroscopy we found evidence for Cp* breakdown products such as acetate. Electrodeposited iridium oxide from ligand free [Ir(OH)6]2– or a colloidal iridium oxide nanoparticles solution produces currents almost 2 orders of magnitude higher with a maximum current of 11 mA cm–2. Also, this deposited material contains, apart from an Ir 4f7/2 species at 62.4 eV, an Ir species at 63.6 eV, which is not observed for any deposit formed by the molecular complexes. Thus, the electrodeposited material of the complexes cannot be directly linked to bulk iridium oxide. Small IrOx clusters containing few Ir atoms with partially incorporated ligand residues are the most likely option for the catalytically active electrodeposit. Our results emphasize that structure–activity relationships obtained with sacrificial oxidants do not necessarily translate to electrochemical conditions. Furthermore, other factors, such as electrodeposition and catalyst degradation, play a major role in the electrochemically driven water oxidation and should thus be considered when optimizing molecular catalysts.

Post-periodontal surgery propounds early repair salivary biomarkers by 1H NMR based metabolomics.

Oral microflora is a well-orchestrated and acts as a sequential defense mechanism for any infection related to oral disease. Chronic periodontitis is a disease of a microbial challenge to symbiosis and homeostasis. Periodontal surgery is the most promising cure with repair process during periodontal regeneration. It has an encouraging outcome in terms of early recovery biomarkers. Saliva of periodontal surgery subjects with the chronic periodontitis have been evaluated by 1H NMR spectroscopy in search of possible early metabolic differences that could be obtained in order to see the eradication of disease which favours the symbiotic condition. The study employed 1H NMR spectroscopy on 176 human saliva samples in search of distinctive differences and their spectral data were further subjected to multivariate and quantitative analysis. The 1H NMR study of periodontal surgery samples shows clear demarcation and profound metabolic differences when compared with the diseased condition. Several metabolites such as lactate, ethanol, succinate, and glutamate were found to be of higher significance in periodontal surgery in contrast to chronic periodontitis subjects. The PLS-DA model of the studied group resulted in R2 of 0.83 and Q2 of 0.70. Significant metabolites could be considered as early repair markers for chronic periodontitis disease as they are being restored to achieve symbiosis. The study, therefore, concluded the early recovery process of the diseased subjects with the restoration of possible metabolomic profile similar to the healthy controls.

Triazole derived azo-azomethine dye as a new colorimetric anion chemosensor.

In the pursue of developing anion sensors, an efficient triazole derived azo-azomethine dye chemosensor (S) that differentially senses F‾ and AcO‾ ions has been reported. The ions recognition ability of S was investigated by colorimetric and UV-visible spectroscopic methods. Interestingly, this chemosensor molecule is virtually inactive in presence of other anions such as Cl‾, Br‾ and I‾ and HSO4‾. We have further presented a ratiometric approach to differentiate F‾ and AcO‾ ions. The reversibility of F‾ ion binding with S was established by the addition of Ca(NO3)2 to the fluoride bound S, which led to the regeneration of S. The quantum chemical calculation of energies of unbound and bound S has been employed using Density Functional Theory (DFT) to understand the interaction between chemosensor and anions. Evidence in support of fluoride-induced deprotonation of a O-H bond during the detection of F⁻ ion has been demonstrated by employing 1H NMR titration experiments.

Long-Lasting Complex Reaction Behavior in a Closed Ferroin-Bromate-Hydroxybenzenesulfonate System.

The bromate-phenolsulfonate reaction was found to exhibit spontaneous oscillations in a batch reactor, where the addition of small amounts of ferroin would result in nonoscillatory behavior. As the ferroin concentration was increased, the system produced very rich nonlinear behavior, including three isolated oscillatory regimes that were separated by as long as 48 h nonoscillatory period. The long-lasting nonlinear behavior may be attributed to the slow desulfonation of phenolsulfonate in an acidic solution, forming phenol-like intermediates. However, unlike the bromate-phenol oscillator, oxygen was found to greatly influence the reaction, and various complex oscillations could be observed by tuning the oxygen concentration. Mechanistic studies performed through employing 1H NMR spectroscopy and mass spectrometry to measure intermediate species at different stages of the reaction were able to identify 1,4-benzoquinone, 2-bromo-1,4-benzoquinone, 2,6-dibromo-1,4-benzoquinone, and 2,4,6-tribromophenol as major components during the reaction.

Conformational Dynamics and Exchange Kinetics of N-Formyl and N-Acetyl Groups Substituting 3-Amino-3,6-dideoxy-α-d-galactopyranose, a Sugar Found in Bacterial O-Antigen Polysaccharides.

Three dimensional shape and conformation of carbohydrates are important factors in molecular recognition events and the N-acetyl group of a monosaccharide residue can function as a conformational gatekeeper whereby it influences the overall shape of the oligosaccharide. NMR spectroscopy and quantum mechanics (QM) calculations are used herein to investigate both the conformational preferences and the dynamic behavior of N-acetyl and N-formyl substituents of 3-amino-3,6-dideoxy-α-d-galactopyranose, a sugar and substitution pattern found in bacterial O-antigen polysaccharides. QM calculations suggest that the amide oxygen can be involved in hydrogen bonding with the axial OH4 group primarily but also with the equatorial OH2 group. However, an NMR J coupling analysis indicates that the θ1 torsion angle, adjacent to the sugar ring, prefers an ap conformation where conformations <180° also are accessible, but does not allow for intramolecular hydrogen bonding. In the formyl-substituted compound 4JHH coupling constants to the exo-cyclic group were detected and analyzed. A van't Hoff analysis revealed that the trans conformation at the amide bond is favored by ΔG° ≈ - 0.8 kcal·mol-1 in the formyl-containing compound and with ΔG° ≈ - 2.5 kcal·mol-1 when the N-acetyl group is the substituent. In both cases the enthalpic term dominates to the free energy, irrespective of water or DMSO as solvent, with only a small contribution from the entropic term. The cis-trans isomerization of the θ2 torsion angle, centered at the amide bond, was also investigated by employing 1H NMR line shape analysis and 13C NMR saturation transfer experiments. The extracted transition rate constants were utilized to calculate transition energy barriers that were found to be about 20 kcal·mol-1 in both DMSO-d6 and D2O. Enthalpy had a higher contribution to the energy barriers in DMSO-d6 compared to in D2O, where entropy compensated for the loss of enthalpy.

HIF-1α inhibition by diethylstilbestrol and its polyacetal conjugate in hypoxic prostate tumour cells: insights from NMR metabolomics

In this study, we have employed 1H NMR metabolomics to assess the metabolic responses of PC3 prostate tumour cells to hypoxia and to pharmacological HIF-1α inhibition by DES or its polyacetal conjugate tert-DES. Oxygen deprivation prompted a number of changes in intracellular composition and metabolic activity, mainly reflecting upregulated glycolysis, amino acid catabolism and other compensatory mechanisms used by hypoxic cells to deal with oxidative imbalance and energy deficit. Cell treatment with a non-cytotoxic concentration of DES, under hypoxia, triggered significant changes in 17 metabolites. Among these, lactate, phosphocreatine and reduced glutathione, whose levels showed opposite variations in hypoxic and drug-treated cells, emerged as possible markers of DES-induced HIF-1α inhibition. Furthermore, the free drug had a much higher impact on the cellular metabolome than tert-DES, particularly concerning polyamine and pyrimidine biosynthetic pathways, known to be tightly involved in cell proliferation and growth. This is likely due to the different cell pharmacokinetics observed between free and conjugated DES. Overall, this study has revealed a number of unanticipated metabolic changes that inform on DES and tert-DES direct cellular effects, providing further insight into their mode of action at the biochemical level.

X-ray crystallographic, spectroscopic, electrochemical and computational studies on axially ligation of ZnTPP with pyridine derivative anchored to aza-crown macrocyclic ligand

The complexes of zinc tetraphenylporphyrin (ZnTPP) with the azacrown macrocycles bearing pyridine moiety (bp, 1p) as the axial ligand were synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, IR, 1H and 13C NMR, fluorescence, UV–Vis, together with TD DFT calculations. Solution study by employing 1H NMR spectroscopy for ZnTPPbenz and ZnTPPH complexes elucidated that the pyridine moiety was bonded through the fifth-coordination site on the zinc metal atom. The observation of hypsochromic shifts of ca. 15nm for Q(0,1) (the strongest emission) as well as ca. 15nm for Q(0,0) (the second) bands testified to significant difference in the fluorescence of ZnTPPbenz and ZnTPPH. Meanwhile, the absorption spectroscopy signified a bathochromic shift for these complexes in comparison with the ZnTPP. The calculation of association constant for these compounds showed that ZnTPPbenz was more stable complex than ZnTPPH. while the fluorescence studies indicated on thermodynamic similarity of the ligation of ZnTPP with bp and 1p. The electrochemical behavior of these complexes was studied by cyclic voltammetry in CH2Cl2.

Tuning Electrocatalytic Activity of Ultrathin Pd Shells: CO2 to Fuels

It is well established that thin metal layers on a foreign support can exhibit very distinctive electrocatalytic activity with respect to bulk electrodes. In the case of d­-metals, changes in reactivity can be rationalised in terms of the so-called ligand or strain (also known as geometric) effects. Although is commoly argued that ligand effects are rather short range (sub-monolayer to few atomic layers), it is notoriusly difficult to experimentally differentiate the contributions from these two phenomena. In this contribution, we shall explore ligand and strain effects on the electrocatalytic properties of Au-Pd core-shell nanoparticles towards CO2 reduction to fuels. The electrochemical properties and product generation are probed by off-line 1H NMR, differential electrochemical mass spectrometry (DEMS), on-line Mass spectrometry (OLEMS) and in-situ FTIR. Thin Pd shells were grown onto 20 nm Au nanoparticles employing a colloidal synthesis method at low temperatures, generating continuous shells with tuneable mean thickness between 1.3±0.1 (CS1) and 9.9±1.1 nm (CS10). Selected area electron diffraction patterns revealed that the effective Pd strain decreases from 3.5 to less than 1% in this thickness range, which is consistent with strain relaxtion mechanisms at Au {111} surfaces. DEMS was used to calculate the faradaic efficiency associated with the CO2 reduction vs hydrogen evolution at the core-shell nanostructures supported on a porous carbon layer. The data show that over 90% of the faradaic charge in the range between 0.0 to -0.5 V vs RHE is consumed in CO2 conversion at CS1 nanoparticles, as opposed to approximately 40% in the case of CS10. The analysis of the electrolyte solution employing 1H NMR revealed the formation of HCOO- only in the case of CS10 over a narrow potential range centred at -0.4 V, with faradaic efficiencies close to 30%. Furthermore, CH4 and C2H6 were also detected using OLEMS at potentials as negative as -0.7 V at the CS10 nanoparticles. No products in solution were detected In the case of CS1, indicating that CO is the main product generated over the entire potential range. The contrast in reaction pathway and electrocatalytic performance are rationalised in terms of the CO affinity to the Pd nanoshells. To probe this, in-situ FTIR studies were performed revealing that the potential dependence of the adsorbed C-O stretching band (stark slope) is significantly weaker on CS1 in comparison to CS10. Furthermore, the effective CO coverage increases with increasing Pd thickness, reaching values reported for polycrystalline bulk Pd electrodes in the case of CS10. These results show that CO has a significantly weaker binding to strain Pd shells (CS1). Finally DFT calculations are used to estimate the contributions of the so-called ligand and strain effects on the local density of states of the Pd d-band. The calculations strongly suggest that the key parameters contributing to the change in mechanism is the effective lattice strain.

Urinary metabolic profiling of cisplatin nephrotoxicity and nephroprotective effects of Orthosiphon stamineus leaves elucidated by 1H NMR spectroscopy

Orthosiphon stamineus (OS) is a popular medicinal herb used in traditional Chinese medicine as a diuretic agent and for renal system disorders. This study employed 1H NMR based metabolomics approach to investigate the possible protective activity of OS in cisplatin induced nephrotoxicity owing to its diuretic and antioxidant activities. Aqueous (OSAE) and 50% aqueous ethanolic (OSFE) extracts of OS leaves were orally administered at 400mg/kg BW doses to rats which were then intraperitoneally injected with cisplatin at 5mg/kg BW dose. The 1H NMR profile of the urine samples collected on day 5 after cisplatin administration were analyzed by multivariate pattern recognition techniques, whereby 19 marker metabolites suggestive in the involvement of TCA cycle, disturbed energy metabolism, altered gut microflora and BCAA metabolism pathways were identified. It was observed that OSFE caused significant changes (p<0.05) in the levels of 8 markers namely leucine, acetate, hippurate, lysine, valine, 2-oxoglutarate, 3-HBT and acetoacetate resulting in a moderate ameliorative effect, however, it did not completely protect from nephrotoxicity. OSAE did not demonstrate significant down regulatory effects on any markers, albeit, it potentiated the cisplatin nephrotoxicity by inducing significant increase in glucose, glycine, creatinine, citrate, TMAO, acetate and creatine levels. A Principal Component Analysis (PCA) of the 1H NMR spectra of OS extracts identified that OSFE had higher concentrations of the secondary metabolites such as caffeic acid, chlorogenic acid, protocatechuic acid and orthosiphol, among others. Whereas, OSAE was characterized by higher concentrations of acetate, lactate, succinic acid, valine and phosphatidylcholine. This research denotes the first comprehensive analysis to identify the effects of OS extracts on cisplatin nephrotoxicity.

Complex Nonlinear Behavior in the Bromate–2‐Aminophenol Reaction

ABSTRACTThe bromate–2‐aminophenol reaction in a batch reactor was investigated in this research, in which both simple and sequential oscillations were observed. The occurrence of sequential oscillations were found to be very sensitive to changes of the initial concentrations, where decreasing the concentration of sulfuric acid or sodium bromate or increasing the 2‐aminophenol concentration caused the two oscillation windows to coalesce. Lowering the reaction temperature from 30 to 5°C also caused the two oscillation windows to merge into one. A phase diagram in the bromate–sulfuric acid concentration plane demonstrates that sequential oscillations only occur within a narrow band of conditions. Mechanistic studies of the system through employing 1H NMR and mass spectrometry suggest that a dibrominated ortho‐benzoquinone is a major product. The oxidation of 2‐aminophenol, on the other hand, can lead to the formation of pyrocatechol, which may be the substrate responsible for the second set of oscillations.