Addition Of Other Ions Research Articles

Investigation of Surface Layers on Biological and Synthetic Hydroxyapatites Based on Bone Mineralization Process.

In this review, the current status of the influence of added ions (i.e., SiO44-, CO32-, etc.) and surface states (i.e., hydrated and non-apatite layers) on the biocompatibility nature of hydroxyapatite (HA, Ca10(PO4)6(OH)2) is discussed. It is well known that HA is a type of calcium phosphate with high biocompatibility that is present in biological hard tissues such as bones and enamel. This biomedical material has been extensively studied due to its osteogenic properties. The chemical composition and crystalline structure of HA change depending on the synthetic method and the addition of other ions, thereby affecting the surface properties related to biocompatibility. This review illustrates the structural and surface properties of HA substituted with ions such as silicate, carbonate, and other elemental ions. The importance of the surface characteristics of HA and its components, the hydration layers, and the non-apatite layers for the effective control of biomedical function, as well as their relationship at the interface to improve biocompatibility, has been highlighted. Since the interfacial properties will affect protein adsorption and cell adhesion, the analysis of their properties may provide ideas for effective bone formation and regeneration mechanisms.

A Schiff base luminescent chemosensor for selective detection of Zn2+ in aqueous medium

Luminescent chemosensors based on Schiff bases have drawn tremendous research interest owing to their easy synthesis, enriched photophysical properties, and potential applications in biology and materials science. A dinitrophenyl-based Schiff base molecular probe (L) was synthesized and characterized to estimate its selective detection of Zn2+. The probe L exhibits weak emission in the DMSO-H2O solvent mixture due to excited-state intramolecular proton transfer (ESIPT). Interestingly, fluorescence is enhanced with the addition of Zn2+ to the DMSO-H2O solution of L, whereas the emission remains unchanged with the addition of other ions. This specifies that probe L acts as a selective chemosensor for Zn2+. The binding stoichiometry for the L: Zn2+ complex is 1:1, which was calculated using the Benesi-Hildebrand plot from fluorescence data. Furthermore, the binding modes are also supported by density functional theory (DFT) calculation. The binding constant and detection limits are 6.35 × 107 M−1 and 1.1 × 10−8 M, respectively. The L-Zn2+ complex formation is reversible upon the addition of a strong chelating EDTA ligand. In addition, L is also used to detect Zn2+ in living Hela cells and selective sensing of Zn2+ in the solid phase.

Highly efficient activation of peroxymonosulfate by illite-based ultrafine cobalt oxide for the degradation of polyvinyl alcohol

A catalyst was prepared using illite coated with Co3O4 to activate peroxymonosulfate (PMS) for polyvinyl alcohol (PVA) degradation. The variance of valence of specific elements, functional groups, surface morphology, and pore structure of fresh illite, fresh Co3O4@illite and used Co3O4@illite were also investigated, reflecting the excellent stability of the Co3O4@illite catalyst. Degradation experiments confirmed that OH∙, 1O2, and SO4∙- produced by oxygen cavitation reaction acted a significant part in PVA degradation. Moreover, when initial pH = 7, catalyst dosage = 2.0 g/L, PMS concentration = 40 g/L, T = 298 K, the best PVA removal efficiency was got. Also, the adding of H2PO4− and Cl− concentration could inhibit the degradation of PVA at first and then promoted, while the addition of other ions (i.e., HCO3− and CO32−) always inhibited degradation reaction. The transformation products on the possible degradation pathway of PVA were then proposed. The strategy of this study gave a new perspective for the coming design of the natural-mineral-based catalysts to effectively treat waste through the Fenton like processes.

A novel D-A-D-typed rod-like fluorescent material for efficient Fe(Ⅲ) and Cr(Ⅵ) detection: Synthesis, structure and properties

Rod-like fluorescent material (4,7-di-pyrrol-1-yl-benzo[1,2,5]thiadiazole) with D-A-D structure is successfully designed and synthesized by introducing functional pyrrole group on benzothiadiazole molecule. Theoretical and experimental methods are adopted to deeply analyze its electronic structure, microstructure and optical properties. Upon the addition of Fe(Ⅲ) or Cr(Ⅵ), it immediately shows fluorescence quenching phenomenon while the addition of other ions exhibits no obvious quenching effect. The corresponding results reveal that DPYBT is quite promising for the fluorescence detection of Fe(Ⅲ) and Cr(Ⅵ), and the limit of detection for them are 3.04 μM and 43.5 nM, respectively. Meanwhile, it is practical for the visible detection in real environment. It also performs a great potential in search of new drugs towards 4DDM protein.

A facile synthetic route toward air-stable magnetic nanoalloys with Fe–Ni/Fe–Co core and iron oxide shell

Air-stable bimetallic spherically shaped Fe–Ni and Fe–Co magnetic nanoparticles (MNPs), having an average size of 15 nm and core–shell structure, were synthesized by a simple wet chemical method under ambient conditions. For the first time, sodium borohydride reduction method, commonly applied for the syntheses of metal nanoparticles, was used for the preparation of well-defined Fe–Ni and Fe–Co nanoalloys, avoiding exploitation of any organic solvent. This approach allows a large scale production of nanoparticles specifically stabilized by an iron oxyhydroxide shell without a need of secondary functionalization. Transmission electron microscopy, X-ray powder diffraction, X-ray fluorescence, magnetization, and Mossbauer data demonstrate a core–shell nature of the as-synthesized nanoparticles. The nanoparticle core is of metallic origin and is inhomogeneous at the atomic level, consisting of iron-rich and iron-poor alloy phases. The composition of the shell is close to the ferrihydrite and its role lies in prevention of oxidation-induced degradation of nanoparticle properties. The core is ferromagnetic at and below room temperature, experiencing superparamagnetic relaxation effects due to a reduced size of nanoparticles, whereas the shell is completely superparamagnetic at 300 K and magnetically orders below ~25 K. Both developed types of magnetic nanoalloys exhibit a strong magnetic response under applied magnetic fields with a high magnetization values achievable at relatively low applied magnetic fields. Beside this, the highly biocompatible chemical composition of the nanoparticle shell and ability of its chemical modification by substitution or addition of other ions or molecules further empower the application potential of these MNPs, especially in the field of biomedicine.

A chemodosimer based on a core-substituted naphthalene diimide for fluoride ion detection

We have demonstrated the use of a core-substituted naphthalene diimide (c-NDI) bearing trimethylsilylacetylene moieties which is capable of being utilised as a colorimetric and fluorescent chemodosimeter for anions. The detection of anions was carried out by desilylation of the detector. A significant change, visible to the naked eye, was observed only upon addition of F − ions; addition of other ions, such as Cl −, Br −, HSO 4 - , AcO − and H 2 PO 4 - resulted in no distinct changes. Modifications of the electronic properties of the c-NDI upon addition of fluoride ions were characterised by means of UV–vis, fluorescence and 1H NMR spectroscopy.

Investigation on FTIR spectra of barium calcium titanate ceramics

Barium titanate, which is applied in many fields, is a kind of very important ferroelectric material because it is lead free. Its physical properties are changed by replacement or addition of other ions. Here, barium calcium titanate ((Ba,Ca)TiO3) ceramics are prepared. The concentration of calcium is up to 20 at.%. The Fourier transformation infrared spectroscopy (FTIR) measurement is carried out in order to reveal the vibration of crystal lattices. The influence of the replacement on the interaction between Ti and O can be observed by investigating the absorption peak of the Ti–O bond. The wavenumber of absorption peak of Ti–O bond becomes larger with increase of the content of Ca, even though the concentration of Ti is not changed. The wavenumber of absorption peak in (Ba0.95Ca0.05)TiO3 is near 525 cm−1 while that in (Ba0.80Ca0.20)TiO3 is near 550 cm–1. It is attributed to the decrease of the cell size. The length of Ti–O bond is shortened by replacement of Ca. Then the interaction between Ti and O is enhanced. The similar phenomenon is observed in (Ba,Mg)TiO3 and alkali doped BaTiO3 materials as well, supporting the mechanism. Furthermore, the aging effect in (Ba,Ca)TiO3 and (Ba,Mg)TiO3 systems is observed. The former exhibits a good stability when the latter shows unstable FTIR spectra. The influence of point defects on the aging effect is discussed. These results indicate that the FTIR measurement is helpful to study the relationship between the structure and physical properties of ferroelectric materials.

Silver-catalyzed bioleaching of low-grade copper ores.: Part I: Shake flasks tests

A study of the effect of different variables (inoculation, pulp density, [Ag], nutrient medium, pH and [Fe 3+]) on the silver-catalyzed bioleaching of a low-grade copper sulfide ore has been carried out in shake flasks. Chalcopyrite was the dominant copper mineral in the ore. Preliminary tests showed that addition of other ions (Sb, Bi, Co, Mn, Ni and Sn) did not enhance the copper dissolution rate. Conversely, an inoculation with mesophilic microorganisms and the addition of silver had a markedly catalytic effect on the extraction of copper. The kinetics of the silver-catalyzed chalcopyritic ore bioleaching was greatly affected by pulp density and silver concentration. Small amounts of silver (14.7 g Ag/kg Cu) dramatically accelerated the copper dissolution process while large amounts (294.12 g Ag/kg Cu) had an inhibitory effect. The copper dissolution rate was slightly affected in the range of pH between 1.2 and 2.5 but was significantly slower at pH 3.0. The effect of [Fe 3+] in the presence of silver was studied both in abiotic and biotic conditions. High ferric iron concentrations in abiotic tests recovered similar copper amounts (∼ 95%) to those obtained without or with low [Fe 3+] in the presence of bacteria. The leaching of copper from the low-grade copper ore can be very effectively enhanced with silver and mesophilic microorganisms. For that system, the onset of oxidizing conditions starts at an Eh value slightly higher than 650 mV. Above that critical value of potential the copper dissolution rate slows down. This also corresponds with the completion of the leaching process. As the potential rises past 650 mV, the copper extraction reaches a plateau.

Síntese de pigmentos cerâmicos por precipitação química

Os pigmentos cerâmicos são substâncias capazes de desenvolver cor em sólido inorgânico (cerâmica ou vidro) quando nele dispersar mantendo-se insolúvel no mesmo, sem reação química com o mesmo, nas elevadas temperaturas de processamento. Óxidos de cobre dão origem a pigmentos verdes que se decompõem em temperaturas relativamente baixas (em torno de 900 ºC) enquanto adição de outros íons em sua composição poderá melhorar a sua estabilidade térmica e facilitar a sua utilização em revestimentos cerâmicos queimados em altas temperaturas. O presente trabalho teve por objetivo sintetizar, pelo método da precipitação (ou co-precipitação) química, pós de óxidos de cobre e de manganês, tanto puros quanto misturados destinados ao uso em esmaltes decorativos de matriz vítrea. Para tal fim, pó de frita de vidro foi produzido pela fusão de feldspato do Seridó (divisa entre Paraíba e Rio Grande do Norte). Massas selecionadas, 5 a 10% em peso, de pigmentos foram misturadas com o referido pó de frita e a barbotina resultante foi aplicada sobre a superfície de placas de alumina densa, seguindo-se secagem e queima em escolhidas temperaturas. As cores dos recobrimentos obtidos foram avaliadas por medidas colorimétricas usando o sistema CIEL*a*b* e os resultados variaram em função da composição e teor de pigmentos, bem como da temperatura de queima. Constatou-se que os pigmentos de óxidos puros de cobre e de manganês deram tonalidades mais claras do que aquelas fornecidas pelo pigmento misto de cobre e de manganês.

The influence of carboxylate ions on the growth of β-FeOOH particles

Colloidal β-FeOOH particles were produced by hydrolysis of FeCl3 solutions doped with varied amounts of formate, lactate, oxalate, tartarate, pyromellitate and EDTA ions at 100 °C. The resulting particles were characterized by X-ray diffraction, transmission electron microscopy, thermogravimetric-differential thermal analysis, Fourier transform-infrared spectroscopy, elemental analysis, and the adsorption of nitrogen and water. With increasing concentration of added carboxylate ions, the mean modal size of the particles formed increased at low concentrations and decreased after passing the maximum. The crystallite sizes also revealed a maximum on adding EDTA, oxalate and lactate ions, while they monotonically decreased with the addition of other ions. Doping with tartarate and pyromellitate ions by more than 7 and 10 mol%, respectively, produced amorphous particles containing a large amount of these ions. The particles formed with 20 mol% tartarate ions adsorbed water selectively.

A 1H NMR study of the effects of metal ions, cholesterol and [formula omitted] on phase transitions in the inner and outer monolayers of phospholipid vesicular membranes

A novel method is described which allows study of the effect of various asymmetries across a phospholipid bilayer. High resolution, 1H NMR spectra of dipalmitoyl phosphatidylcholine single-bilayer vesicles are obtained at various temperatures in the presence of the lanthanide ions Pr 3+ and Gd 3+. The spectra are used to detect separately the phase transitions which occur in each monolayer of the bilayer. 1. 1. The separate 1H NMR signals from the inner and outer head-groups of the vesicles are obtained using a concentration of 6 mM Pr 3+ in the extravesicular solution. The effect of addition of other ions, Ca 2+, Mg 2+ and K +, to the extra- or intravesicular solution is studied. It is found that interaction of metal ions with the head-groups of one monolayer can be transmitted to the other monolayer and alters the temperature and extent of the phase transitions and pre-transitions observed in each layer. If a suitable metal ion concentration gradient is set up across the bilayer then the two monolayers can be in different phases at temperatures near the phase transition. 2. 2. Using 0.2 mM Gd 3+ in the extra- or intravesicular solutions indicates that there are differences between the phase behaviour and mobility of the lipid in the inner and outer monolayers, which can be attributed to their difference in curvature. 3. 3. Dipalmitoyl phosphatidylcholine vesicles containing 0–50 mol% cholesterol are studied using the same techniques and the effect of increasing concentration of cholesterol on each monolayer is observed. The data obtained indicate that even for a symmetrical distribution of cholesterol its presence can reverse the effect of a metal ion concentration gradient on the relative fluidity of the two monolayers. At 15 mol% cholesterol the bilayer is very susceptible to lysis at temperatures near the phase transition. 4. 4. When n- alkanes are incorporated into dipalmitoyl phosphatidylcholine bilayers they effect the temperature of the phase transitions, depending on their chain length. The stability of the bilayer is also affected, but only at temperatures near T c , and by alkanes of similar hydrocarbon chain length to those in the acyl chains of the lipid. There is thus a striking correlation between the chain length-dependent effect of alkanes as promotors of chemical carcinogenesis and their ability to de-stabilise the phospholipid bilayer.

A 7Li nuclear magnetic resonance study of solutions of lithium and ammonium ions with nitrilotriacetic acid

The possibility has been explored of using the 7Li resonance to measure complex formation in solution between nitrilotriacetic acid (NTA) and lithium ions. It has been found that, as the proportions of lithium and NTA are varied, the 7Li chemical shift changes in such a way as to suggest the formation of a complex Li(NTA)25–. The results are explained on the basis of equilibria involving this complex, the already known LiNTA2–, Li+aq., and NTA3–. The addition of other ions also affects the 7Li chemical shift, and the formation of complexes between these ions and NTA is inferred. The results for the ammonium ion can be explained by the formation of complexes NH4(NTA)2– and (NH4)2NTA–.