A study of the thermal behavior of the system of zirconium and neodymium dipyvaloylmethanates

TG-DTA method was used to study the thermal behavior of the Zr(thd)₄/[Nd(thd)₃]₂ system (thd = 2,2,6.6-tetramethylheptane-3,5-dionato) in the condensed phase. Data were obtained on the kinetics of vaporization of individual beta-diketonate precursors and variously prepared mixtures. A mass-spectrometric monitoring of the gas-phase composition was employed to examine the thermal stability of vapors and to study in situ how individual dipyvaloylmethanates Zr(thd)₄ and Nd(thd)₃ and the two-component system Zr(thd)₄–Nd(thd)₃ are thermally decomposed in a vacuum and in the presence of oxygen. It was found that there is no chemical interaction between the precursors in the whole temperature range under study, but rather pronounced effects of nonadditivity of the thermal parameters are observed for the mixtures examined.     

Comparison of stationary phases for packed column supercritical fluid chromatography based upon ionic liquid motifs: a study of cation and anion effects

A class of stationary phases for packed column supercritical fluid chromatography (SFC), referred to as immobilized ionic liquids (IILs), is evaluated with a two-part study: (1) a cation effect study and (2) an anion effect study. The former study compares six different IILs (tripropylphosphonium, tributylphosphonium, methyl-imidazolium, benzyl-imidazolium, triphenylphosphonium, and 4,4′-bipyridyl) on silica gel, evaluating their performance in SFC with all the counter anions as trifluoroacetate (TFA⁻). In the latter study, the stationary phase consisted of a bonded tributylphosphonium cation and varying counter anions (acetate, TFA⁻, chloride, NTf₂⁻, and perchlorate). An order of retentivity was established for the cation effect study, and the favorable behavior of phosphonium-based stationary phases is reported for the first time in SFC. It was not possible to always assign a retentivity order for the anion effect study, but wide variations in selectivity are noted for different anions showing the tunable nature of this class of stationary phases.     

Study of isotope exchange reactions by double labelling

This paper presents the method of double labelling in the study of the kinetics of homogeneous isotope exchange reactions. This method was tested by the determination of the Sn(II)−Sn(IV) exchange rate in hydrochloric acid medium. The system was labelled by the tracer^119mSn [initially in the Sn(IV) state]; when the isotope equilibrium was established, Sn(IV) was again labelled by tracer¹¹³Sn. The separation of Sn(II) and Sn(IV) in the given time of exchange was performed by the extraction of Sn(IV)-hydroxyquinolate into chloroform. The specific activities of the separated components were determined from the ratio of¹¹³Sn and^119mSn activities. The exchange rate was calculated from the time dependence of specific activities. The advantage and possibilities of the method of double labelling in the study of isotope exchange are discussed.     

Adsorption of aqueous Hg (II) by a novel poly(aniline‐co‐o‐aminophenol)/mesoporous silica SBA‐15 composite

A novel poly(aniline‐co‐o‐aminophenol) (PAOA)/mesoporous silica SBA‐15 nanocomposite was synthesized and investigated for adsorption of Hg (II) from aqueous solutions of wide pH range. A chemical oxidation method was employed for polymerization of aniline and o‐aminophenol on an ordered SBA‐15 template to obtain a significantly enlarged BET surface area of the adsorbent. Efficiency study revealed that the PAOA/SBA‐15 could reach a maximum Hg (II) adsorption capacity of over 400 mg/g. Kinetic study showed that the Hg (II) adsorption by the PAOA/SBA‐15 fitted a pseudo‐second‐order kinetic model, indicating that the mercury adsorption process was predominantly controlled by chemical process. The results of this study also proved that the adsorbed Hg (II) could be effectively desorbed from the PAOA/SBA‐15 in 0.1M HCl and 5% sulfocarbonide solutions. Associated adsorption mechanism was also investigated by means of Fourier transform infrared (FTIR) and X‐ray photoelectron spectroscopy (XPS) techniques. Copyright © 2010 John Wiley & Sons, Ltd.     

Relationship of rotational correlation time from EPR spectroscopy and protein-membrane interaction

A study was carried out to determine if rotational correlation time of spin-labeled hen egg lysozyme (HEL) interacting with ultrafiltration membranes could be used to infer protein-membrane interaction. Polysulfone and cellulosic membranes, which have notably different adsorption properties, and membranes with varying pore sizes were used in this study. Based on this study, it was determined that the rotational correlation time does reflect variations in protein adsorption and pore plugging on membranes. The rotational correlation times for the highly adsorbent polysulfone (2.82 × 10⁻⁸ s) were significantly higher than those obtained from proteins on cellulosic membranes (0.62 × 10⁻⁸ s) and from those in solution (0.17 × 10⁻⁸ s). Rotational correlation time was also increased due to steric hindrance associated with pore plugging, although it was not as significant as the adsorption effect. This study indicates that the rotational time constant can be used to infer the type of protein-membrane interaction.     

Effective biosorption of arsenic from water using La(III) loaded carboxyl functionalized watermelon rind

Arsenic is highly toxic and carcinogenic element that mainly enters into our body through drinking water and caused adverse effect even at low concentration. A new type of cation exchanger is developed from waste biomass of watermelon rind after increasing the carboxyl functional groups by saponification. Saponified Watermelon Rind (SWR) was further loaded with La(III) to attenuate the contamination of As(III) from water. Characterization of biosorbent was performed using Fourier Transform Infra-Red (FTIR) spectroscopy, Field emission Scanning Electron Microscopy (Fe-SEM,) Energy Dispersive X-ray (EDX) spectroscopy and zeta potential analysis. Arsenic speciation of sorption product through X-ray photoelectron spectroscopic (XPS) analysis revealed that As(III) is partially converted into As(V) during biosorption process. The biosorption tests for As(III) were explored under different operating conditions. La(III)-SWR towards As(III) biosorption was best described by Langmuir biosorption isotherm and pseudo second order kinetic model. At a pH of 12.08, the optimum biosorption capacity was found to be 37.73 ± 0.12, 48.78 ± 0.09, 62.50 ± 0.11 mg/g, respectively at temperatures 298 K, 303 K and 308 K. The existance of chloride and nitrate showed negligible interference whereas sulphate and phosphate significantly inhibits As(III) biosorption. Thermodynamic study showed spontaneous and endothermic nature As(III) biosorption onto La(III)-SWR. The sorbed As(III) was eluted almost completely using 2 M NaOH. The findings of this study insinuated that La(III)-SWR biosorbent investigated in this study can be a low cost, environmentally benign and eco-friendly material for the treatment of aqueous solution polluted with arsenic ions.     

Antioxidant and antimicrobial study of Schefflera vinosa leaves crude extracts against rice pathogens

Plant extracts are one of the best possible sources of bioactive molecules, and are being used globally as an antioxidants and natural antimicrobial compounds. In current study, Schefflera vinosa leaves extract was prepared through Soxhlet extraction procedure using methanol and chloroform as solvents. The extract was investigated for total antioxidant, phenolic and flavonoid contents, free radical scavenging and antimicrobial activities. The free radical scavenging activities were evaluated through 2,2- diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis-3-ethylbenzotiazolin-6-sulfonic acid (ABTS) and Ferric-reducing/ antioxidant power (FRAP) assay. The antimicrobial activity of extract was determined through poisoned food method. The methanolic extract has exhibited high antioxidant, phenolic, and flavonoid activities compared to chloroform extract. Similarly, free radical scavenging activities (ABTS, DPPH and FRAP) were higher in methanolic extract. Further, Fourier-Transform Infrared Spectroscopy (FTIR) used to determine the functional group and Gas chromatography-mass spectrometry (GC–MS) to elucidate volatile composition of the crude extract. Different functional group like N-H, O-H, C-O, C-N, C-H, C=O, C≡C and C-O-H presence indicate the existence of many metabolites in the extracts. GC–MS study identified 61 compounds and subsequently, these molecules were screened virtually using DockThor. Furthermore, antimicrobial study was confirmed against rice pathogens like Magnaporthe oryzae (M. oryzae) and Xanthomonas oryzae pv. oryzae (Xoo). Molecular docking study further suggested that phytomolecules (3-Isopropoxy-1,1,1,7,7,7-hexamethyl-3,5,5-tris (trimethylsiloxy) tetrasiloxane, and 2-Methoxy-5-methylthiophene) targets Histone Deacetylase (HDAC) of M. oryzae and Peptide Deformylase (PDF) of Xoo, which could inhibit their growth. Hence, this study indicated that Schefflera vinosa extracts could be an important ingredient as an antioxidant as well as antimicrobial agent against rice pathogens.     

Antibacterial Activity of a Promising Antibacterial Agent: 22-(4-(2-(4-Nitrophenyl-piperazin-1-yl)-acetyl)-piperazin-1-yl)-22-deoxypleuromutilin

A novel pleuromutilin derivative, 22-(4-(2-(4-nitrophenyl-piperazin-1-yl)-acetyl)-piperazin-1-yl)-22-deoxypleuromutilin (NPDM), was synthesized in our laboratory and proved excellent antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). In this study, more methods were used to further study its preliminary pharmacological effect. The antibacterial efficacy and toxicity of NPDM were evaluated using tiamulin as the reference drug. The in vitro antibacterial activity study showed that NPDM is a potent bactericidal agent against MRSA that induced time-dependent growth inhibition and a concentration-dependent post-antibiotic effect (PAE). Toxicity determination showed that the cytotoxicity of NPDM was slightly higher than that of tiamulin, but the acute oral toxicity study proved that NPDM was a low-toxic compound. In an in vivo antibacterial effect study, NPDM exhibited a better therapeutic effect than tiamulin against MRSA in a mouse thigh infection model as well as a mouse systemic infection model with neutropenia. The 50% effective dose (ED₅₀) of NPDM in a Galleria mellonella infection model was 50.53 mg/kg. The pharmacokinetic properties of NPDM were also measured, which showed that NPDM was a rapid elimination drug in mice.     

Facile synthesis of 4″-O-alkyl-(–)-EGCG derivatives through regioselective deacetylative alkylation

Therapeutic potential of the D-ring methyl ethers of (–)-epigallocatechin-3-gallate [(–)-EGCG] warrants extensive structure–activity relationship study of various D-ring ethers of (–)-EGCG but, for this purpose, efficient synthetic strategy needs to be developed. In this study, efficient preparation of the 4″-O-alkyl-(–)-EGCGs (4a–e) was demonstrated using KI/K₂CO₃-promoted deacetylative alkylation of peracetyl (–)-EGCG, which could be broadly utilized for the preparation of various D-ring alkyl ethers of (–)-EGCG and thereby extensive structure–activity relationship study.     

Spectral and thermal studies of some 4-(O-acetyl)glycopyranosylaminopyrimidine derivatives

A spectral study (IR and UV spectroscopies) of seven 4-(O-acetyl)glycopyranosylaminopyrimidine derivatives has been carried out. The thermal study of the compounds allowed us to characterize the following processes: (i) desolvations, (ii) solid-solid transitions, (iii) melting, (iv) pyrolytic decompositions. Through the IR spectral study it was established that pyrolytic decompositions of all the compounds start with the acetyl groups. The reaction orders and activation energies of the deacetylation processes have been calculated.     

Electrodeposition of Se on carbon-supported Pt nanoparticles by cyclic voltammetry

Cyclic voltammetry (CV) is a powerful and popular electrochemical technique widely used to study the surface structure of materials through the electrochemical behaviors. Herein CV is utilized to study the electrochemical deposition of selenium (Se) on carbon black-supported Pt nanostructures. We synthesized carbon-loaded platinum nanoparticles (Pt/C) by microwave method and studied the electrochemical behavior of selenium on them. Through the experiment of changing the reverse potential, the corresponding relationship between the Se deposition peak and stripping peak was clarified and the deposition and stripping process of Se was proposed. Meanwhile, we synthesized cubic and octahedral nanocrystals of Pt, and used CV to study the Se deposition on these nanosctructures supported by carbon. It was found that the relative intensity of UPD peaks on Pt is different, as Pt_cube@C is dominated by (100) and Pt_oct@C electrode is dominated by (111) while Pt@C falls in between.

     

Proficiency testing as a tool for implementing internal quality control: the case of ochratoxin A in cocoa powder

This paper describes the interlaboratory study aimed at assessing the performance of 18 laboratories (14 national and 4 European) for Ochratoxin A (OTA) determination in cocoa powder samples. The study was tested at three levels of OTA covering the range in which presumably European regulatory limits could fall in the near future. For the extraction step, almost all laboratories used an aqueous solution of sodium hydrogen carbonate with the exception of one laboratory using dichloromethane consistently with the ELISA procedure adopted in the study. The clean-up step was performed by utilizing the immunoaffinity columns by the two main manufacturers (R-Biopharm Rhone and VICAM) and for the quantitative analysis, HPLC was used by all the participants except one using ELISA. From the output of the study, it can be concluded that at low level (0.19 μg/kg) 10 out of 18 (56%), at medium level (0.45 μg/kg) 11 out of 18 (61%), and at high level (1.45 μg/kg) 12 out of 18 (67%) results fell within the satisfactory ranges. This interlaboratory study provides an estimate of the performance of national and European laboratories involved in OTA determination in cocoa powder samples, which sounds extremely valuable in view of potential future legislation by the European Commission.     

Photo-Activated Circularly Polarized Luminescence Film Based on Aggregation-Induced Emission Copper(I) Cluster-Assembled Materials

In this study, a pair of chiral copper(I) cluster-assembled materials (R/S- 2 ) was prepared, exhibiting unique photo-response characteristics with a concentration-wavelength correlation property in DMSO solution. By the combination of R/S- 2 with a polymethyl methacrylate (PMMA) matrix, the first photo-activated circularly polarized luminescence (CPL) film was developed, the CPL signal (g_lum=9×10⁻³) of which could be induced by UV light irradiation. Moreover, the film exhibited a reversible photo-response and extremely good fatigue resistance. Mechanism study revealed that the photo-response properties of the R/S- 2 solution and film are attributed to the aggregation-induced emission (AIE) characteristics of R/S- 2 and a photo-induced deoxygenation process. This study enriches the types of luminescent cluster-assembled molecules and provides a new strategy for the construction of metal cluster-based stimuli-responsive composite materials.     

Documentation of bioactive principles of the flower from Caralluma retrospiciens (Ehrenb) and in vitro antibacterial activity – Part B

The purpose of this study was to explore the biocomponents of flowers from Caralluma retrospiciens (Ehrenb). The study investigated the FT-IR and GC–MS spectral analysis of flower from C. retrospiciens (Ehrenb). A flower concentrate (FC) was prepared and the functional groups were determined by FT-IR spectroscopy study. FT-IR analysis showed the presence of significant compounds at frequency 3287.45, 2850.32, 2595.91, 2524.69, 2041.07 cm⁻¹. The GC–MS study demonstrated the presence of unique pharmaceutically important compounds. The extract was characterized by the presence of unique compounds such as “7,8-Epoxylanostan-11-ol, 3-acetoxy”, “Pregnan-20-one, 5,6-epoxy-3-hydroxy-, (3á,5á,6á)-”, “Benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-, methyl ester”, “Hexadecanoic acid, methyl ester”, “Dasycarpidan-1-methanol, acetate”, etc. The antibacterial effect of the FC showed a wide spectrum of activity against the screened human pathogenic bacteria. The activity was predominantly against Gram-negative bacteria.     

Photoluminescent columnar zinc(II) bimetallomesogen of tridentate [ONO]-donor Schiff base ligand

A new zinc(II) bimetallomesogenic complex, [Zn₂L₂], of tridentate [ONO]-donor Schiff base ligand (L = N-(2-hydroxyethyl)-4-hexadecyloxysalicylaldimines) was synthesised and their mesomorphic and photoluminescence properties were investigated. The compounds were characterised by Fourier transform infrared spectroscopy (FTIR), ¹H and ¹³C nuclear magnetic resonance (NMR), ultraviolet-visible spectroscopy (UV-Vis) spectroscopy, elemental analyses and fast atom bombardment (FAB) mass spectrometry. The mesomorphic behaviour of the complex was investigated by polarised optical microscopy, differential scanning calorimetry and X-ray diffraction (XRD) study. A rectangular or oblique columnar mesophase is conjectured on the basis of powder X-ray diffraction (PXRD) study. The complex is found to be blue light emitter in solution, in solid and in condensed states with broad emission maxima at ～427–464 nm. The density functional theory (DFT) calculations revealed a distorted square planar structure around each zinc(II) centre in the dinuclear framework. Time-dependent DFT spectral correlative study was undertaken to account for the electronic transition.     

1,2,3-triazole derivative: Synthesis,characterization, DFT,molecular docking study and antibacterial-antileishmanial activities

In this study, 4-((1-(4-chlorobenzyl)-1H-1,2,3-triazole-4-yl)methoxy)-3-methoxybenzaldehyde (I) was synthesized and molecular structure of compound I was confirmed by FTIR and NMR (¹H and ¹³C NMR) spectroscopic methods. The geometric structure of compound I was optimized by DFT/B3LYP method using 6–311++G(d, p) basis set. The molecular docking study was carried out against six different proteins. The antibacterial and antileishmanial activities of compound I were tested by microdilution broth with Alamar blue method and minimum inhibitor concentrations (MIC) were determined. According to the test results, it was found to be effective against eleven types of bacteria at different concentrations (MIC: 312–5000 ​μg/mL). In addition, compound I was not effective against leishmania species at the concentrations that were examined.     

Synthesis and pancreatic lipase inhibitory activities of some 1,2,4-triazol-5(3)-one derivatives

In this study, starting from 4-amino-5-(4-chlorobenzyl)-2,4-dihydro-3H-1,2,4-triazole-3-one ( 1 ), the 4-Amino-5-(4-chlorobenzyl)-2-undecyl-2,4-dihydro-3H-1,2,4-triazol-3-one ( 2 ) was first synthesized and this compound was converted to Schiff base derivatives ( 3a-e ). In the second step of the study, the 2-[3-(4-chlorobenzyl)-5-oxo-1-undecyl-1,5-dihydro-4H-1,2,4-triazole-4-yl]-acetohydrazide ( 6 ), which was used as a key product in the synthesis of many heterocyclic compounds was synthesized in four steps, and then this compound was converted into methylidene acetohydrazide ( 7a-e ), thiosemicarbazide ( 8a-e ), and 1,2,4-triazole-5-thione ( 9a-e ) derivatives. Also, in the last part of the study, 1,2,4-triazole-5-thione derivatives were changed into Mannich bases ( 10a-b ) bearing a 4-phenylpiperazine ring. These new compounds were tested with regard to pancreatic lipase (PL) inhibition activity, and compound 3b , 3d , 7d , 8d , and 9d showed a considerable anti-lipase activity at various concentrations. The activity of compounds 7b (IC₅₀ = 1.45 ± 0.12 μM) was the highest in terms of IC₅₀, comparable to that of orlistat, a well-known PL inhibitor used as an antiobesity drug.     

The Treatment of Water-Based Toxic Waste Using Induction Plasma Technology

A study of the treatment of liquid wastes in a radio frequency (rf) induction plasma reactor is reported. Ethylene glycol was used as a surrogate for the waste because of safety considerations. Thermodynamic analyses demonstrated complete and safe decomposition at the conditions studied. The solution was injected axially into the center of an argon–oxygen plasma operated at a plate power of 50 kW to study blast atomization and operating conditions. A factorial analysis revealed, at a confidence level of 0.99, that both reduction of pressure and liquid flow rate increase the destruction and removal efficiency (DRE) and that a higher plate power increased DRE. The study also revealed that poor atomization was responsible for the reduction of the DRE by 10–15% (to 80–85%) and that 94% of the exothermic energy of the reaction was available for further use. The specific energy requirement (SER) of the process was estimated at 8.33 kWh/kg of solute. This value can be expected to drop significantly with scale-up of the process.     

Size‐Selective Encapsulation of Hydrophobic Guests by Self‐Assembled M4L6 Cobalt and Nickel Cages

Subtle differences in metal–ligand bond lengths between a series of [M₄L₆]^4? tetrahedral cages, where M=Fe^II, Co^II, or Ni^II, were observed to result in substantial differences in affinity for hydrophobic guests in water. Changing the metal ion from iron(II) to cobalt(II) or nickel(II) increases the size of the interior cavity of the cage and allows encapsulation of larger guest molecules. NMR spectroscopy was used to study the recognition properties of the iron(II) and cobalt(II) cages towards small hydrophobic guests in water, and single‐crystal X‐ray diffraction was used to study the solid‐state complexes of the iron(II) and nickel(II) cages.     

Characterization of epoxy prepreg SPX 8800 system by isothermal differential scanning calorimetry

Isothermal Differential Scanning Calorimetry (DSC) was used to study the curing behavior of epoxy prepreg SPX 8800 system, which contains DGEBA/DICY/Diuron (Diglycidyl ether of bisphenol A/Dicyandiamide/Diuron) reinforced by three layers of glass fibre. The rate curves from the DSC study agreed well with those obtained from the isothermal FT Near Infrared (FTNIR) study and similar activation energy was obtained in the range of 92.6 to 87.7 kJ/mol up to 50% total conversion. Modelling of the whole DSC trace with empirical equation dx/dt=kx^m(A-x)ⁿ gave relatively good fitting of the experimental curves (the error is lower than 15%.) in the whole studied cure temperature range (75-110°C) and no significant difference in cure kinetics was observed for both epoxy prepreg and neat resin.