Characterization of antioxidant activity of extracts from Flos Lonicerae

Antioxidants are emerging as prophylactic and therapeutic agents for various diseases. However, little is known about the antioxidant property of the extract from Flos Lonicerae, a medically useful traditional Chinese medicine herb. Here the antioxidant capacity of water, methanolic and 70% ethanolic extracts prepared from Flos Lonicerae to scavenge DPPH radical and reduce Fe³⁺ to Fe²⁺ is evaluated. Chlorogenic acid, a major component of Flos Lonicerae, is identified and further purified from 70% ethanolic extract with HPLC and its antioxidant capacity is also characterized. The content of total phenolic compounds and chlorogenic acid in Flos Lonicerae is determined. The present results demonstrate that all Flos Lonicerae extracts examined here exhibit antioxidant activity and chlorogenic acid is a major contributor to this activity, which implicates that the Flos Lonicerae extract may serve as potential source of natural antioxidants for treatment of some diseases.     

Isotherm and kinetic sorption of some lanthanides and iron from aqueous solution by aluminum silicotitante exchanger

Sorption of La³⁺, Eu³⁺, and Fe³⁺ onto new synthetic inorganic ion exchange material of aluminum silicotitante was investigated. The aluminum silicotitante (EX₁, EX₂, and EX₃) are synthetic with different concentration ratio (0.1:0.1:0.003, 0.1:0.1:0.1, and 0.1:0.1:0.1) at aging time 4, 4, and 1 day, respectively. The equilibrium kinetic for La³⁺, Eu³⁺, and Fe³⁺ onto EX₁, EX₂, and EX₃ materials takes about 120?min which is considered as a fast kinetic process. Sorption results were fitted using different kinetic models such as pseudo-first-order, pseudo-second order, and intraparticle diffusion models. The results indicated that the sorption of La³⁺, Eu³⁺, and Fe³⁺ onto EX₁, EX₂, and EX₃ materials is highly fit with the pseudo-second order model. Equilibrium data were described by the Langmuir, Freundlich isotherm models. The Langmuir isotherm model was fitted to the experimental data better than the Freundlich isotherm. The thermodynamics parameters (positive values of ΔH°, ΔS° and negative values of ΔG°) indicated the binding systems between the materials and adsorbate were endothermic, entropy gained and spontaneous in nature. The experimental data indicated that, aluminum silicotitante could be used as an efficient sorbent for La³⁺, Eu³⁺, and Fe³⁺. Maximum sorption % at equilibrium is 92.7, 99.0, and 78.5% for La³⁺, Eu³⁺, and Fe³⁺, respectively.     

Magnetic properties of the phases Fe2V4O13, FeVMoO7 and Fe4V2Mo3O20

The Curie constant,C, Weiss constant, , effective magnetic moment, _eff, and spectroscopic splitting factor,g, were determined for the Fe³⁺ ions in Fe₂V₄O₁₃, FeVMoO₇ and Fe₄V₂Mo₃O₂₀ at 76–300 K based on measurements of magnetic susceptibility of the phases. The Neel temperature,T _N, of interest was based on the temperature dependence of magnetization of the phases. It was shown that a local antiferromagnetic arrangement of the Fe³⁺ ions in Fe₂V₄O₁₃, FeVMoO₇ and Fe₄V₂Mo₃O₂₀ is already involved at a temperature much higher than the Neel temperature, resulting from the cation-anion-cation superexchange between the Fe³⁺ ions with ad ⁵ configuration.     

Antioxidant Properties of Selected Plant Extracts and Application in Packaging as Antioxidant Cellulose‐Based Films for Vegetable Oil

Selected plant extracts including cinnamon, clove, ginger, green tea and thyme were investigated for their antioxidant activity by using both β‐carotene‐linoleate bleaching agar well diffusion and β‐carotene‐linoleate bleaching broth assays, and for radical scavenging activity against free radicals using a 2,2‐diphenyl‐1‐picrylhydrazyl assay. Undiluted plant extracts (except ginger oil) showed a yellow zone of β‐carotene ranging from 15.3 to 38.2 mm in diameter. At a concentration of 50 μL mL^‐1, thyme yielded the highest antioxidant activity (260%), followed by ginger (254%), cinnamon (108%), clove (106%) and green tea (101%), respectively. Conversely, at a plant extract concentration of 0.39 μL mL^‐1 solution in ethanol, green tea yielded the highest radical scavenging activity (94.3%), followed by clove (93.4%), cinnamon (91.1%), thyme (30.4%) and ginger (8.29%), respectively. The minimum oxidative bleaching inhibitory concentrations (MOBICs) of these plant extracts were determined using a β‐carotene‐linoleate bleaching broth dilution assay ranging from 0.195 to 50 μL mL^‐1. The MOBICs of plant extracts in a range of 0.195–1.56 μL mL^‐1 could reveal an ability to inhibit the oxidation of β‐carotene‐linoleate broth. Cellulose‐based film containing cinnamon, clove or green tea showed positive activity against β‐carotene‐linoleate oxidation and 2,2‐diphenyl‐1‐picrylhydrazyl radicals. Protective effects of plant extracts incorporated in cellulose‐based pouches in stabilizing soybean oil were tested by measuring their peroxide values and free fatty acid contents during accelerated storage. Green tea‐incorporated cellulose‐based pouches exhibited stronger antioxidant properties in soybean oil than do butylated hydroxyanisole‐incorporated cellulose‐based pouches. This study showed the potential use of plant extracts as antioxidants for food packaging application. Copyright © 2011 John Wiley & Sons, Ltd.     

Mechanochemical synthesis of salicylic acid–formaldehyde chelating co-polymer

A mechanochemical synthesis of a co-polymer of salicylic acid and formaldehyde is reported. New IR absorbance bands found after the performance of the mechanochemical synthesis are attributed to the formation of a salicylic acid–formaldehyde co-polymer. Dislocation deformation along slide planes in the salicylic acid structure occurs in the course of the mechanochemical activation causing no essential changes in the more stable hydrogen bonds net. The weaker inter-layer bonds in the acid structures are broken during activation, but are restored soon after the completion of the process. Polycondensation reaction occurs as a result of the mechanochemical process of the salicylic acid–formaldehyde mixture. The obtained co-polymer is a chelating agent capable of binding Pb²⁺, Cu²⁺, and Fe³⁺ ions. A comparison was made of the ion exchange capacity and metal ion binding capacity of the mechanochemically produced co-polymer with the co-polymer synthesized using the conventional “wet” method.     

Rate of heating and sintering temperature effect on the electrical properties of Nd ferrite

The real part of the dielectric constant () and the dielectric loss angle (tan ) as well as the ac conductivity of ferrite Mg_1+x Ti _x Nd _y Fe_2–2x–y O₄ 0.1 x 0.9 at fixed Nd concentration of 0.025 were measured at different temperatures as a function of frequencies. The variation of activation energy as a function of the applied frequency was reported. The obtained data were discussed on the basis of the valence exchange between (Fe³⁺, Fe²⁺), (Fe²⁺, Nd³⁺) and (Fe²⁺, Ti⁴⁺). Also the effect of sintering temperature and heating rate of preparation were discussed.     

Fe(III)-Naphthazarin Metal–Phenolic Networks for Glutathione-Depleting Enhanced Ferroptosis–Apoptosis Combined Cancer Therapy

Nowadays, Fenton chemistry-based chemodynamic therapy (CDT) is an emerging approach to killing tumor cells by converting endogenous H₂O₂ into cytotoxic hydroxyl radicals (·OH). However, the elimination of ·OH by intracellular overexpressed glutathione (GSH) results in unsatisfactory antitumor efficiency. In addition, the single mode of consuming GSH and undesirable drug loading efficiency cannot guarantee the efficient cancer cells killing effect. Herein, a simple one-step strategy for the construction of Fe³⁺-naphthazarin metal–phenolic networks (FNP MPNs) with ultrahigh loading capacity, followed by the modification of NH₂-PEG-NH₂, is developed. The carrier-free FNP MPNs can be triggered by acid and GSH, and rapidly release naphthazarin and Fe³⁺, which is further reduced to Fe²⁺ that exerts Fenton catalytic activity to produce abundant ·OH. Meanwhile, the Michael addition between naphthazarin and GSH can lead to GSH depletion and thus achieve tumor microenvironment (TME)-triggered enhanced CDT, followed by activating ferroptosis and apoptosis. In addition, the reduced Fe²⁺ as a T₁-weighted contrast agent endows the FNP MPNs with magnetic resonance imaging (MRI) functionality. Overall, this work is the debut of naphthazarin as ligands to fabricate functional MPNs for effectively depleting GSH, disrupting intracellular redox homeostasis, and enhancing CDT effects, which opens new perspectives on multifunctional MPNs for tumor synergistic therapy.     

Conduction in Mn substituted Ni-Zn ferrites

The d.c. electrical resistivity ‘ρ’ and thermoelectric power ‘α’ are studied as a function of temperature for Mn substituted ferrites with general formula Zn_0·3Ni_0·7+x Mn _x Fe_2−2x O₄. At lower Mn concentrations, the increase in d.c. resistivity is attributed to the hindering of Verwey mechanism Fe²⁺ ⇌ Fe³⁺ due to stable bonds of Mn³⁺ + Fe²⁺ pair. The decrease in resistivity at higher Mn concentrations (i.e. whenx > 0·15) is attributed to the formation of Mn³⁺ cluster and Ni²⁺ ⇌ Ni³⁺. The activation energy values show one to one correspondence with resistivity values. The compositional variation of thermoelectric power showsn-type behaviour for the samples withx < 0·2 whereasp-type behaviour for the samples withx ⩾ 0·2. Thep −n transition is attributed to the formation of Ni³⁺, Fe²⁺ + vacancies which act asp-type carriers. The temperature dependences ofα, ρ, and mobility clearly confirm the conduction mechanism to be due to polaron hopping.     

Dielectric behaviour of MgFe2O4 prepared from chemically beneficiated iron ore rejects

Chemically beneficiated high silica/alumina iron ore rejects (27–76% Fe₂O₃) were used to synthesize iron oxides of purity 96–98% with SiO₂/Al₂O₃ ratio reduced to 0.03. The major impurities on chemical beneficiations were Al, Si, and Mn in the range 2–3%. A 99.73% purity Fe₂O₃ was also prepared by solvent extraction method using methyl isobutyl ketone (MIBK) from the acid extracts of the ore rejects. The magnesium ferrite, MgFe₂O₄, prepared from these synthetic iron oxides showed high resistivity of ∼ 10⁸ ohm cm. All ferrites showed saturation magnetization, 4πM_s, in the narrow range of 900–1200 Gauss and the Curie temperature,T, _cof all these fell within a small limit of 670 ± 30 K. All ferrites had low dielectric constants (ε′), 12–15, and low dielectric loss, tan δ, which decreased with the increase in frequency indicating a normal dielectric dispersion found in ferrites. The presence of insignificant amount of polarizable Fe²⁺ ions can be attributed to their high resistances and low dielectric constants. Impurities inherent in the samples had no marked influence on the electrical properties of the ferrites prepared from the iron ore rejects, suggesting the possibility of formation of ferrite of constant composition, MgFe₂O₄, of low magnetic and dielectric losses at lower temperatures of 1000°C by ceramic technique.     

Growth and Raman spectra of doped ZnO single crystals

ZnO:M ⁿ⁺(M ⁿ⁺ = Cd²⁺, Co²⁺, Ni²⁺, Sc³⁺, In³⁺, Ga³⁺, Fe³⁺, Te⁴⁺, V⁵⁺) single crystals have been grown under hydrothermal conditions in ZnO-M _x O _y -KOH-LiOH-H₂O systems, and their Raman spectra have been measured under visible (514.5 nm) and near-IR (1064 nm) excitation. The anomalous band between 500 and 600 cm⁻¹ in the Raman spectra of ZnO:Mn²⁺ has A ₁ symmetry and is due to vibrations involving Mn²⁺.     

Surface engineered magnetic nanoparticles for removal of toxic metal ions and bacterial pathogens

Surface engineered magnetic nanoparticles (Fe₃O₄) were synthesized by facile soft-chemical approaches. XRD and TEM analyses reveal the formation of single-phase Fe₃O₄ inverse spinel nanostructures. The functionalization of Fe₃O₄ nanoparticles with carboxyl (succinic acid), amine (ethylenediamine) and thiol (2,3-dimercaptosuccinic acid) were evident from FTIR spectra, elemental analysis and zeta-potential measurements. From TEM micrographs, it has been observed that nanoparticles of average sizes about 10 and 6 nm are formed in carboxyl and thiol functionalized Fe₃O₄, respectively. However, each amine functionalized Fe₃O₄ is of size ∼40 nm comprising numerous nanoparticles of average diameter 6 nm. These nanoparticles show superparamagnetic behavior at room temperature with strong field dependent magnetic responsivity. We have explored the efficiency of these nanoparticles for removal of toxic metal ions (Cr³⁺, Co²⁺, Ni²⁺, Cu²⁺, Cd²⁺, Pb²⁺ and As³⁺) and bacterial pathogens (Escherichia coli) from water. Depending upon the surface functionality (COOH, NH₂ or SH), magnetic nanoadsorbents capture metal ions either by forming chelate complexes or ion exchange process or electrostatic interaction. It has been observed that the capture efficiency of bacteria is strongly dependent on the concentration of nanoadsorbents and their inoculation time. Furthermore, these nanoadsorbents can be used as highly efficient separable and reusable materials for removal of toxic metal ions.     

Synthesis and characterization of zirconium titanium phosphate and its application in separation of metal ions

An advanced inorganic ion exchanger, zirconium titanium phosphate (ZTP) of the class of tetravalent bimetallic acid (TBMA) salt has been synthesized by sol–gel route. ZTP has been characterized for ICP-AES, TGA, FTIR and XRD. Chemical stability of the material in various media-acids, bases and organic solvents has been assessed. Cation exchange capacity (CEC) and effect of calcination (100–500 °C) on CEC has also been studied. Distribution behaviour of metal ions Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺ (d-block), Cd²⁺, Hg²⁺, Pb²⁺, Bi³⁺ (heavy) and La³⁺, Ce³⁺, Th⁴⁺, UO₂²⁺ (f-block) towards ZTP has been studied and distribution coefficient (K_d) determined in aqueous as well as various electrolyte media/concentrations. Based on the differential selectivity, breakthrough capacity (BTC) and elution behaviour of various metal ions towards ZTP, a few binary and ternary metal ion separations have been carried out.     

Iron removal from human plasma based on molecular recognition using imprinted beads

The aim of this study is to prepare ion-imprinted polymers which can be used for the selective removal of Fe³⁺ ions from Fe³⁺-overdosed human plasma. N-Methacryloly-(l)-glutamic acid (MAGA) was chosen as the complexing monomer. In the first step, Fe³⁺ was complexed with MAGA and the Fe³⁺-imprinted poly(HEMA–MAGA) beads were synthesized by suspension polymerization. After that, the template (i.e., Fe³⁺ ions) was removed using 0.1 M EDTA solution. The specific surface area of the Fe³⁺-imprinted poly(HEMA–MAGA) beads was found to be 76.4 m²/g with a size range of 63–140 μm in diameter and the swelling ratio was 75%. According to the elemental analysis results, the beads contained 84.7 μmol MAGA/g polymer. The maximum adsorption capacity was 92.6 μmol Fe³⁺/g beads. The relative selectivity coefficients of imprinted beads for Fe³⁺/Zn²⁺ and Fe³⁺/Cr³⁺ were 17.3 and 48.6 times greater than non-imprinted matrix, respectively. The Fe³⁺-imprinted poly(HEMA–MAGA) beads could be used many times without decreasing their adsorption capacities significantly.     

A rapid and sensitive method for separation of Cu2+ ions from industrial wastewater sample and water samples with methacrylamide‐ethylene glycol dimethacrylate: A new synthesis of molecularly imprinted polymer

In this study, new molecularly imprinted polymer particles (MIP) were synthesised to extract Cu²⁺ ions from aqueous solutions using radical polymerisation. MIP was developed using the methacrylamide‐ethylene glycol dimethacrylate (EGDMA) cross linking agent, methacrylamide monomer, and ACV initiator by the radical polymerisation method. A comparison of various cross linking agents in MIP production showed that the best cross linking agents are EGDMA and gallic acid. The template ions were removed by leaching with 0.100 M HCl. The polymer particles were characterised by FTIR spectroscopy, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The effect of different parameters such as cross linkers, pH, time, maximum adsorption capacity, and kinetic and isotherm adsorption were investigated. The best conditions were determined (pH = 8.0, t = 10 min, and q _m  = 262.53 mg g⁻¹). The adsorption data were best fitted by Freundlich isotherm and pseudo second order kinetic models, as well. Due to its high adsorption capacity and multi‐layer behaviour, this method is an easy, fast and safe way to extract cations. Removal of Cu²⁺ in certified tap water and rain water was demonstrated and the industrial wastewater sample (Charmshahr, Iran) with which the MIP was developed using Methacrylamide‐ Ethylene Glycol Dimethacrylate (EGDMA) was good enough for Cu²⁺ determination in matrices containing components with similar chemical property such as Co²⁺, Zn²⁺, Fe².     

The magnetic properties of Bi0.9Ba0.1Fe0.81M0.09Ti0.1O3 solid solutions (M = Co, Mn, Sc, Al)

Solid solutions with general formula Bi_0.9Ba_0.1Fe_0.81M_0.09Ti_0.1O₃ (M = Co, Mn, Sc, Al) together with parental Bi_0.9Ba_0.1Fe_0.9Ti_0.1O₃ were prepared by the traditional solid state reaction method. Their structural, room temperature magnetic, and dielectric properties were investigated. X-ray diffraction analysis indicated that all samples maintained original R3c space group. M–H hysteresis loop of Co³⁺ doped sample saturated at an applied field of 1 T with spontaneous magnetization of 1.735 emu/g, while Mn⁴⁺ substitution enhanced the magnetization of Bi_0.9Ba_0.1Fe_0.9Ti_0.1O₃ less strongly; addition of Sc³⁺ helped decrease magnetic coercive field while Al³⁺ modified sample exhibited paramagnetic M–H hysteresis loop. Differential scanning calorimetry was applied to determine the Neel temperature (T_N) and the T_N for undoped, Co³⁺, Mn⁴⁺, Sc³⁺, Al³⁺ doped solid solutions were 318.1, 324.3, 335.7, 293.9 and 295.8 respectively. Sc³⁺ substitution had little influence on the dielectric properties of Bi_0.9Ba_0.1Fe_0.9Ti_0.1O₃ while Al³⁺ doping improved its dielectric constant. In contrast, Co³⁺, Mn⁴⁺ doped samples showed decreased permittivity but inhibited tan δ at frequencies larger than 30 kHz.     

Green synthesis of silver nanoparticles using flower extract of Malva sylvestris and investigation of their antibacterial activity

High‐quality colloidal silver nanoparticles (AgNP) were synthesised via a green approach by using hydroalcoholic extracts of Malva sylvestris. Silver nitrate was used as a substrate ion while the plant extract successfully played the role of reducing and stabilising agents. The synthesised nanoparticles were carefully characterised by using transmission electron microscopy, atomic‐force microscopy, energy dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy and UV–vis spectroscopy. The maximum absorption wavelengths of the colloidal solutions synthesised using 70 and 96% ethanol and 100% methanol, as extraction solvents, were 430, 485 and 504 nm, respectively. Interestingly, the size distribution of nanoparticles depended on the used solvent. The best particle size distribution belonged to the nanoparticles synthesised by 70% ethanol extract, which was 20–40 nm. The antibacterial activity of the synthesised nanoparticles was studied on Escherichia coli, Staphylococcus aureus and Streptococcus pyogenes using disk diffusion, minimum inhibitory concentrations and minimum bactericidal concentrations assays. The best antibacterial activity obtained for the AgNPs produced by using 96% ethanolic extract.Inspec keywords: silver, nanoparticles, nanofabrication, antibacterial activity, colloids, particle size, transmission electron microscopy, atomic force microscopy, X‐ray chemical analysis, Fourier transform spectra, infrared spectra, ultraviolet spectra, visible spectra, microorganisms, nanomedicine, biomedical materialsOther keywords: Green synthesis, flower extract, Malva sylvestris, antibacterial activity, high‐quality colloidal silver nanoparticles, hydroalcoholic extracts, plant extract, reducing agents, stabilising agents, transmission electron microscopy, atomic‐force microscopy, energy dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy, UV– vis spectroscopy, colloidal solutions, particle size distribution, Escherichia coli, Staphylococcus aureus, Streptococcus pyogenes, disk diffusion, minimum inhibitory concentrations, minimum bactericidal concentrations assays, ethanolic extract, size 430 nm, size 485 nm, size 504 nm, size 20 nm to 40 nm, Ag     

The calculated defect structure of bulk and {001} surface cation dopants in MgO

Lattice defect calculations are presented for the cation doping of the bulk and {001} surface of MgO by Li⁺, Na⁺, Be²⁺, Ca²⁺, Fe²⁺, Al³⁺, Sc³⁺, Fe³⁺, Ti⁴⁺ and Si⁴⁺. Interionic potentials are derived from electron-gas calculations while the lattice relaxation methods are essentially those introduced by Lidiard and Norgett. An emphasis is placed on the differences between the bulk and surface, and, where possible, a comparison is made with the available experimental data.     

Electron spin resonance linewidths of Fe3+ in magnesium oxide

Electron spin resonance linewidths of Fe³⁺ in single crystal MgO at 9 GHz were examined experimentally and theoretically for a range of Fe³⁺ concentration. In contrast to the behaviour expected from dipolar broadening the experimental derivative peak-to-peak linewidth for the 1/2 ↔ −1/2 transition, about 0.6 mT at 77 K and a polar angle of 0°, was independent of concentration from 140 to 8500 ppm. The calculated dipolar linewidths greatly exceeded those observed and values of the ratio of moments M ₄ ^1/4 /M ₂ ^1/2 derived from the experimental data lay between 1.33 and 1.48. Optical examination, coupled with heat-treatment experiments, confirmed that the predominant valency state present was Fe³⁺. The data suggested that Fe³⁺ entered the lattice substitutionally, occupying magnesium sites, and that the linewidths were determined by exchange narrowing over the whole concentration range examined.     

Boosting electron population in δ-Bi2O3 through iron doping for improved photocatalytic activity

We successfully stabilize the delta phase of bismuth oxide (δ-Bi₂O₃) down to room temperature through a simple hydrothermal method. The prepared δ-Bi₂O₃, which is composed of ultrathin nanosheets, possesses excellent crystallinity. When δ-Bi₂O₃ is doped with Fe³⁺, the photocatalytic activity for the mineralization of a number of refractory organic compounds is improved. The improved photocatalytic activity is caused by an increased electron population upon the Fe³⁺ doping. Additional thermal treatment through a post-calcination at 500?°C under air atmosphere results in further increases of photocatalytic activity due to the improved crystallinity, extended light absorption, and better incorporation of Fe³⁺ into the host lattice.     

Magnetic and electrical properties of lithium borosilicate glasses containing nickel and iron oxides

Measurements of a.c. conductivity, dielectric constants, Mo¨ssbauer spectra and magnetic susceptibility were carried out on samples of composition: 20LiO₂, 31B₂O₅, 34SiO₂, 15 – x NiO, xFe₂O₃ where x = 2.5, 5, 7.5, 10 and 12.5 mol %. It was found that when x is changed from 2.5 to 10 mol % NiO, the conductivity decreases due to the increase of the bridging oxygen ions. When x is increased to greater than 10 mol % NiO, the conductivity increases because of the decrease of the ratio of Fe²⁺Fe³⁺ ions as confirmed from Mo¨ssbauer data. The conductivity has a distinct minimum at 10 mol % NiO. Distribution of relaxation processes was also studied, and two processes were adequate to describe the present experimental data.