Co-removal and recycling of Ba2+ and Ca2+ in hypersaline wastewater based on the microbially induced carbonate precipitation technique: Overlooked Ba2+ in extracellular and intracellular vaterite

This study investigates the co-precipitation of calcium and barium ions in hypersaline wastewater under the action of Bacillus licheniformis using microbially induced carbonate precipitation (MICP) technology, as well as the bactericidal properties of the biomineralized product vaterite. The changes in carbonic anhydrase activity, pH, carbonate and bicarbonate concentrations in different biomineralization systems were negatively correlated with variations in metal ion concentrations, while the changes in polysaccharides and protein contents in bacterial extracellular polymers were positively correlated with variations in barium concentrations. In the mixed calcium and barium systems, the harvested minerals were vaterite containing barium. The increasing concentrations of calcium promoted the incorporation and adsorption of barium onto vaterite. The presence of barium significantly increased the contents of O-CO, N-CO, and Ba-O in vaterite. Calcium promoted barium precipitation, but barium inhibited calcium precipitation. After being treated by immobilized bacteria, the concentrations of calcium and barium ions decreased from 400 and 274 to 1.72 and 0 mg/L (GB/T15454-2009 and GB8978-1996). Intracellular minerals were also vaterite containing barium. Extracellular vaterite exhibited bactericidal properties. This research presents a promising technique for simultaneously removing and recycling hazardous heavy metals and calcium in hypersaline wastewater.

Enhanced boron removal via seed-induced crystal growth of barium perborate in sequential fluidized-bed crystallization

Chemical oxo-precipitation (COP) is an enhanced precipitation method for boron removal with the conversion of boric acid to perborate anions. When using barium-based precipitant, the boron can be effectively precipitated as barium perborates (BaPBs). The phase transformation of BaPBs from amorphous (A-BaPB, Ba(B(OH)3OOH)2) to crystalline (C-BaPB, BaB2(OO)2(OH)4) form is crucial for effective boron removal. However, scaling up this phase transformation of BaPBs is hindered by poor diffusion. This study aims to promote the growth of C-BaPB through seed-induced crystal growth, eliminating the need for phase transformation. By examining the relationship between crystal growth rate and supersaturation, surface spiral growth was identified as the rate-limiting step of the growth of micron-sized seeds near pHpzc. To enable continuous crystal growth, granular seeds of C-BaPB were prepared and employed as the medium for fluidized-bed crystallization (FBC). The system reached steady state 3 hydraulic retention times, achieving 90% boron removal. The effect of surface loading, ionic strength, and dosages on steady-state crystal growth rate was studied, revealing a shift of the rate-limiting step in FBC to diffusion. Lastly, the system that constituted of two FBCs in-series for sequential crystallization of A-BaPB and C-BaPB was demonstrated. The integrated system provided 97.8% of boron removal from synthetic wastewater containing 500 mg-B/L, with 92.3% of boron crystallized on the granular seeds of BaPBs.

Navigating through the coordination preferences of heavy alkaline earth metals: Laying the foundations for 223Ra- and 131/135mBa-based targeted alpha therapy and theranostics of cancer

The clinical success of [223Ra]RaCl2 (Xofigo®) for the palliative treatment of bone metastases in patients with prostate cancer has highlighted the therapeutic potential of α-particle emission. Expanding the applicability of radium-223 in Targeted Alpha Therapy of non-osseous tumors is followed up with significant interest, as it holds the potential to unveil novel treatment options in the comprehensive management of cancer. Moreover, the use of barium radionuclides, like barium-131 and -135m, is still unfamiliar in nuclear medicine applications, although they can be considered as radium-223 surrogates for imaging purposes. Enabling these applications requires the establishment of chelators able to form stable complexes with radium and barium radionuclides. Until now, only a limited number of ligands have been suggested and these molecules have been primarily inspired by existing structures known for their ability to complex large metal cations. However, a systematic inspection of chelators specifically tailored to Ra2+ and Ba2+ has yet to be conducted. This work delves into a comprehensive investigation of a series of small organic ligands, aiming to unveil the coordination preferences of both radium-223 and barium-131/135m. Electronic binding energies of both metal cations to each ligand were theoretically computed via Density Functional Theory calculations (COSMO-ZORA-PBE-D3/TZ2P), while thermodynamic stability constants were experimentally determined for Ba2+-ligand complexes by potentiometry, NMR and UV-Vis spectroscopies. The outcomes revealed malonate, 2-hydroxypyridine 1-oxide and picolinate as the most favorable building blocks to design multidentate chelators. These findings serve as foundation guidelines, propelling the development of cutting-edge radium-223- and barium-131/135m-based radiopharmaceuticals for Targeted Alpha Therapy and theranostics of cancer.

Broadband sensitized near-infrared emission in Eu2+-Nd3+ co-doped BaAl2O4 as a potential spectral modulator for silicon solar cells

The near-infrared (NIR) down-conversion process for broadband sensitization has been studied in Eu2+-Nd3+ co-doped BaAl2O4. This material has a broad absorption band of 200-480 nm and can convert photons in the visible region into NIR photons. The NIR emission at 1064 nm, attributed to the Nd3+:4F3/2 → 4I11/2 transition, matches the bandgap of Si, allowing Si solar cells to utilize the solar spectrum better. The energy transfer (ET) process between Eu2+ and Nd3+ was demonstrated using photoluminescence spectra and luminescence decay curves, and Eu2+ may transfer energy to Nd3+ through the cooperative energy transfer (CET) to achieve the down-conversion process. The energy transfer efficiency (ETE) and theoretical quantum efficiency (QE) were 68.61% and 156.34%, respectively, when 4 mol% Nd3+ was introduced. The results indicate that BaAl2O4:Eu2+-Nd3+ can serve as a potential modulator of the solar spectrum and is expected to be applied to Si solar cells.

Barium Concentration-Dependent Anomalous Electrophoresis of Synthetic DNA Motifs

The structural integrity, assembly yield, and biostability of DNA nanostructures are influenced by the metal ions used to construct them. Although high (>10 mM) concentrations of divalent ions are often preferred for assembling DNA nanostructures, the range of ion concentrations and the composition of the assembly products vary for different assembly conditions. Here, we examined the unique ability of Ba2+ to retard double crossover DNA motifs by forming a low mobility species, whose mobility on the gel is determined by the concentration ratio of DNA and Ba2+. The formation of this electrophoretically retarded species is promoted by divalent ions such as Mg2+, Ca2+, and Sr2+ when combined with Ba2+ but not on their own, while monovalent ions such as Na+, K+, and Li+ do not have any effect on this phenomenon. Our results highlight the complex interplay between the metal ions and DNA self-assembly and could inform the design of DNA nanostructures for applications that expose them to multiple ions at high concentrations.

Controllable synthesis of barium carbonate nano- and microparticles for SPECT and CT imaging

The design and synthesis of nano- and microcarriers for preclinical and clinical imaging are highly attractive due to their unique features, for example, multimodal properties. However, broad translation of these carriers into clinical practice is postponed due to the unknown biological reactivity of the new components used for their synthesis. Here, we have developed microcarriers (∼2-3 μm) and  nanocarriers (<200 nm) made of barium carbonate (BaCO3) for multiple imaging applications in vivo. In general, barium in the developed carriers can be used for X-ray computed tomography, and the introduction of a diagnostic isotope (99mTc) into the BaCO3 structure enables in vivo visualization using single-photon emission computed tomography. The bioimaging has shown that the radiolabeled BaCO3 nano- and microcarriers had different biodistribution profiles and tumor accumulation efficiencies after intratumoral and intravenous injections. In particular, in the case of intratumoral injection, all the types of used carriers mostly remained in the tumors (>97%). For intravenous injection, BaCO3 microcarriers were mainly localized in the lung tissues. However, BaCO3 NPs were mainly accumulated in the liver. These results were supported by ex vivo fluorescence imaging, direct radiometry, and histological analysis. The BaCO3-based micro- and nanocarriers showed negligible in vivo toxicity towards major organs such as the heart, lungs, liver, kidneys, and spleen. This study provides a simple strategy for the design and fabrication of the BaCO3-based carriers for the development of dual bioimaging.

Structural insight and in silico prediction of the pharmacokinetic parameters and toxicity of alkaline earth metal compounds strontium and barium with the non-steroidal anti-inflammatory drug nimesulide

In the crystals of alkaline earth metal compounds strontium and barium with the non-steroidal anti-inflammatory drug nimesulide, the strontium cation is nine-coordinated with a distorted tricapped trigonal prismatic geometry TCTPR-9, whereas the ten-coordinated barium ion exhibits a distorted tetracapped trigonal prismatic geometry TCTPR-10.

Investigation and optimization of In-Vitro behaviour of Perovskite barium titanate as a scaffold and protective coatings

The piezoelectric effect is widely known to have a significant physiological function in bone development, remodeling, and fracture repair. As a well-known piezoelectric material, barium titanate is particularly appealing as a scaffold layer to improve bone tissue engineering applications. Currently, the chemical bath deposition method is used to prepare green synthesized barium titanate coatings to improve mechanical and biological characteristics. Molarity of the solutions, an essential parameter in chemical synthesis, is changed at room temperature (0.1-1.2 Molar) to prepare coatings. The XRD spectra for as deposited coatings indicate amorphous behavior, while polycrystalline nature of coatings is observed after annealing (300 °C). Coatings prepared with solutions of relatively low molarities, i.e. from 0.1 to 0.8 M, exhibit mixed tetragonal - cubic phases. However, the tetragonal phase of Perovskite barium titanate is observed using solution molarities of 1.0 M and 1.2 M. Relatively high value of transmission, i.e. ∼80%, is observed for the coatings prepared with high molarities. Band gap of annealed coatings varies between 3.47 and 3.70 eV. For 1.2 M sample, the maximum spontaneous polarization (Ps) is 0.327x10-3 (μC/cm2) and the residual polarization (Pr) is 0.072x10-3 (μC/cm2). For 1.2M solution, a high hardness value (1510 HV) is recorded, with a fracture toughness of 28.80 MPam-1/2. Low values of weight loss, after dipping the coatings in simulated body fluid, is observed. The antibacterial activity of BaTiO3 is tested against E. coli and Bacillus subtilis. Drug encapsulation capability is also tested for different time intervals. As a result, CBD-based coatings are a promising nominee for use as scaffold and protective coatings.

BaGdF5 Nanophosphors Doped with Different Concentrations of Eu3+ for Application in X-ray Photodynamic Therapy

X-ray photodynamic therapy (XPDT) has been recently considered as an efficient alternative to conventional radiotherapy of malignant tissues. Nanocomposites for XPDT typically consist of two components—a nanophosphor which re-emits X-rays into visible light that in turn is absorbed by the second component, a photosensitizer, for further generation of reactive oxygen species. In this study, BaGdF₅ nanophosphors doped with different Eu:Gd ratios in the range from 0.01 to 0.50 were synthesized by the microwave route. According to transmission electron microscopy (TEM), the average size of nanophosphors was ~12 nm. Furthermore, different coatings with amorphous SiO₂ and citrates were systematically studied. Micro-CT imaging demonstrated superior X-ray attenuation and sufficient contrast in the liver and the spleen after intravenous injection of citric acid-coated nanoparticles. In case of the SiO₂ surface, post-treatment core–shell morphology was verified via TEM and the possibility of tunable shell size was reported. Nitrogen adsorption/desorption analysis revealed mesoporous SiO₂ formation characterized by the slit-shaped type of pores that should be accessible for methylene blue photosensitizer molecules. It was shown that SiO₂ coating subsequently facilitates methylene blue conjugation and results in the formation of the BaGdF₅: 10% Eu³⁺@SiO₂@MB nanocomposite as a promising candidate for application in XPDT.

A (partial) resolution of binding enthalpy discrepancies in ITC studies of Ba2+crown ether complexation: The importance of calibration

By conducting binding experiments at a range of temperatures T using isothermal titration calorimetry (ITC), one can obtain two estimates of the binding enthalpy - calorimetric (ΔH°_cal) from the experiments at each T, and van't Hoff (ΔH°_vH) from the T dependence of the binding constant K°. From thermodynamics it is clear that these two must be identical, but early efforts to demonstrate this for ITC data indicated significant inconsistency. In an extensive 2004 study of the Ba²⁺ + 18-crown-6 ether complexation used in prior comparisons, Mizoue and Tellinghuisen found modest (10-20%) but statistically significant differences, which were tentatively attributed to problems converting the calorimetric estimates to their standard state values, as implied by the superscript ° in the notation. In the present work the 2004 results are reanalyzed using results obtained since then from temperature, heat, and volume calibration of the instrument and a better determination of the data variance function required for the weighted least-squares fitting of the data. The new results show consistency for temperatures 5-30 °C but persistent statistically significant differences from 35-46 °C. Several possible explanations for the remaining discrepancies are examined, with methods that include fitting the K and ΔH_cal data together.

Biologically Compatible Lead-Free Piezoelectric Composite for Acoustophoresis Based Particle Manipulation Techniques

This research paper is concentrated on the design of biologically compatible lead-free piezoelectric composites which may eventually replace traditional lead zirconium titanate (PZT) in micromechanical fluidics, the predominantly used ferroelectric material today. Thus, a lead-free barium-calcium zirconate titanate (BCZT) composite was synthesized, its crystalline structure and size, surface morphology, chemical, and piezoelectric properties were analyzed, together with the investigations done in variation of composite thin film thickness and its effect on the element properties. Four elements with different thicknesses of BCZT layers were fabricated and investigated in order to design a functional acoustophoresis micromechanical fluidic element, based on bulk acoustic generation for particle control technologies. Main methods used in this research were as follows: FTIR and XRD for evaluation of chemical and phase composition; SEM-for surface morphology; wettability measurements were used for surface free energy evaluation; a laser triangular sensing system-for evaluation of piezoelectric properties. XRD results allowed calculating the average crystallite size, which was 65.68 Å3 confirming the formation of BCZT nanoparticles. SEM micrographs results showed that BCZT thin films have some porosities on the surface with grain size ranging from 0.2 to 7.2 µm. Measurements of wettability showed that thin film surfaces are partially wetting and hydrophilic, with high degree of wettability and strong solid/liquid interactions for liquids. The critical surface tension was calculated in the range from 20.05 to 27.20 mN/m. Finally, investigations of piezoelectric properties showed significant results of lead-free piezoelectric composite, i.e., under 5 N force impulse thin films generated from 76 mV up to 782 mV voltages. Moreover, an experimental analysis showed that a designed lead-free BCZT element creates bulk acoustic waves and allows manipulating bio particles in this fluidic system.

Comparative Study of Silk-Based Magnetic Materials: Effect of Magnetic Particle Types on the Protein Structure and Biomaterial Properties

This study investigates combining the good biocompatibility and flexibility of silk protein with three types of widely used magnetic nanoparticles to comparatively explore their structures, properties and potential applications in the sustainability and biomaterial fields. The secondary structure of silk protein was quantitatively studied by infrared spectroscopy. It was found that magnetite (Fe3O4) and barium hexaferrite (BaFe12O19) can prohibit β-sheet crystal due to strong coordination bonding between Fe3+ ions and carboxylate ions on silk fibroin chains where cobalt particles showed minimal effect. This was confirmed by thermal analysis, where a high temperature degradation peak was found above 640 °C in both Fe3O4 and BaFe12O19 samples. This was consistent with the magnetization studies that indicated that part of the Fe in the Fe3O4 and BaFe12O19 was no longer magnetic in the composite, presumably forming new phases. All three types of magnetic composites films maintained high magnetization, showing potential applications in MRI imaging, tissue regeneration, magnetic hyperthermia and controlled drug delivery in the future.

Pressure Induced Spin Crossover and Magnetic Properties of Multiferroic Ba3NbFe3Si2O14

Recently, the iron containing langasite-type crystal Ba₃NbFe₃Si₂O₁₄ has attracted great attention as a new magnetically induced multiferroic. In this work, magnetic, structural and electronic properties of the multiferroic Ba₃NbFe₃Si₂O₁₄ were investigated by several methods, including synchrotron X-ray diffraction, Raman spectroscopy and synchrotron Mössbauer source technique at high quasi-hydrostatic pressures (up to 70 GPa), created in diamond anvil cells. At room temperature, two structural transitions at pressures of about 3.0 and 17.5 GPa were detected. Mössbauer studies at high pressures revealed a radical change in the magnetic properties during structural transitions. At pressures above 18 GPa, the crystal transforms into two magnetic fractions, and in one of them the Néel temperature (T_N) increases by about four times compared with the T_N value in the initial phase (from 27 to 115 K). At pressures above 50 GPa, a spin crossover occurs when the fraction of iron Fe³⁺ ions in oxygen octahedra transits from the high-spin (HS, S = 5/2) to the low-spin (LS, S = 1/2) state. This leads to a new change in the magnetic properties. The magnetic ordering temperature of the LS sublattice was found to be of about 22(1) K, and magnetic correlations between HS and LS sublattices were studied.

Dual-emitting barium based metal-organic nanosheets as a potential sensor for temperature and anthrax biomarkers

The development of novel 2D materials, due to the promising applications they have enabled through their unique properties, has attracted increasingly more research interest. In this regard, novel dual-emitting coordination polymer nanosheets were developed by doping Eu³⁺ and Tb³⁺ ions into the nanostructures of the [Ba(DPA)₂(H₂O)₂] _n (DPA = dipicolinic acid) coordination polymer (BCP). Single crystal x-ray crystallography revealed that BCP is a 1D coordination polymer and its three-dimensional supramolecular architecture is constructed with a relatively strong hydrogen bonding in the ac crystallographic plane and weak non-covalent interactions along the b axis. Using energetic ultrasound irradiations, synthesis of nanoscale BCP along with the unzipping of the weak interactions between the ac layers was accomplished. The resulting BCP nanosheets was used as the host lattice and was doped with Eu³⁺ and Tb³⁺ ions. Remarkably, the sensing ability of both Eu³⁺ and Tb³⁺ doped coordination polymer (Ln@BCP) nanosheets towards temperature and the DPA anthrax biomarker were investigate. The high relative sensitivity value of 2.42% K^-1 and their reusability, makes Ln@BCP nanosheets an ideal candidate for the nanothermometry. They also exhibited high selective detection characteristics towards the DPA anthrax biomarker with a 0.03 nM detection limit. Therefore, Ln@BCP nanosheets can also be considered as an efficient multi-responsive optical sensor.

Cell-laden alginate dialdehyde-gelatin hydrogels formed in 3D printed sacrificial gel

Alginate dialdehyde-gelatin (ADA-GEL) hydrogels have been reported to be suitable matrices for cell encapsulation. In general, application of ADA-GEL as bioink has been limited to planar structures due to its low viscosity. In this work, ring shaped constructs of ADA-GEL hydrogel were fabricated by casting the hydrogel into sacrificial molds which were 3D printed from 9% methylcellulose and 5% gelatin. Dissolution of the supporting structure was observed during the 1st week of sample incubation. In addition, the effect of different crosslinkers (Ba2+ and Ca2+) on the physicochemical properties of ADA-GEL and on the behavior of encapsulated MG-63 cells was investigated. It was found that Ba2+ crosslinked network had more than twice higher storage modulus, and mass decrease to 70% during incubation compared to 42% in case of hydrogels crosslinked with Ca2+. In addition, faster increase in cell viability during incubation and earlier cell network formation were observed after Ba2+ crosslinking. No negative effects on cell activity due to the use of sacrificial materials were observed. The approach presented here could be further developed for cell-laden ADA-GEL bioink printing into complex 3D structures.

Geochemical conditions conducive for retention of trace elements and radionuclides during shale-fluid interactions

Produced water generated during unconventional oil and gas extractions contains a complex milieu of natural and anthropogenic potentially toxic chemical constituents including arsenic (As), chromium (Cr), and cadmium (Cd), naturally occurring radioactive materials (NORMs) including U and Ra, and a myriad of organic compounds. The human-ecological health risks and challenges associated with the disposal of produced water may be alleviated by understanding geochemical controls on processes responsible for the solubilization of potentially hazardous natural shale constituents to produced water. Here, we investigated, through a series of batch treatments, the leaching behavior of As, Se, Cu, Fe, Ba, Cr, Cd, and radioactive nuclides U, Ra from shale to produced water. Specifically, the effect of four major controls on element mobility was studied: (1) solution pH, (2) ionic strength of the solution, (3) oxic-anoxic conditions, and (4) an additive used in fracking fluid. The mobilization of metals and metalloids from shale was greatest in treatments containing sodium persulfate, an oxidant and a commonly used additive in fracture fluid. In the high ionic strength treatments, dissolved Ba concentrations increased 5-fold compared to low ionic strength treatments. Overall, anoxic conditions superimposed with low pH resulted in the largest increase of dissolved metals and radionuclides such as Ra. Overall, our results suggest that (1) limiting pore water acidification by injection of alkaline fluid in carbonate-low shale and (2) minimizing strong oxidizing conditions in shale formations may result in cost-effective in situ retention of produced water contaminants.

Tm3+/Yb3+:BaMoO4 phosphor for high-performance thermometry operating in the first biological window

The development of optical thermometers operating within the first biological window (650-1000 nm) has drawn great interest lately in the biological and medical fields. Here a new type of luminescent thermometer relying on the intensity ratio between G₄1-F₄3 (652 nm) and F_2,33-H₆3(691 nm) transitions in Tm³⁺/Yb³⁺:BaMoO₄ phosphor is reported under 980 nm excitation. The thermometry is found to be independent on the excitation power, benefiting the reduction of the measurement error. Moreover, it exhibits extremely high absolute sensitivity ranging from 210.5×10^-4 to 1034.5×10^-4  K^-1 in 298-498 K. The maximal relative sensitivity and temperature resolutions (1.36%  K^-1 and 0.37 K, respectively) are also among the highest values of those previous thermometric materials. This Letter provides guidance in selecting the suitable emission bands to construct the ratiometric luminescent thermometers with high performance.

Energy transfer induced white-light-emitting phosphor by co-doping Ce3+ , Tb3+ and Mn2+ into the single Ba9 Lu2 Si6 O24 host

In the Ba₉ Lu₂ Si₆ O₂₄ (BLS) host, Ce³⁺ shows cyan emissions peaking at 490 nm under 400 nm excitations. BLS:Tb³⁺ only can be effectively excited by 254 nm light and gives rise to green emissions at 553 nm. However, both the cyan and green emissions can be obtained in BLS:Ce³⁺ ,Tb³⁺ under 400 nm excitations due to effective energy transfers from Ce³⁺ to Tb³⁺ . BLS:Mn²⁺ shows red emissions peaking at 610 nm under 414 nm excitations. By co-doping Ce³⁺ , Tb³⁺ and Mn²⁺ , tunable full-color emissions were obtained. The BLS:0.3Ce³⁺ ,0.6Tb³⁺ ,0.15Mn²⁺ single phosphor exhibits a white light with a high color rendering index of 85 and a correlated color temperature of 5480 K under 400 nm excitation.

Association equilibria of divalent ions on the surface of liposomes formed from phosphatidylcholine

Divalent ions, in particular calcium ions, constitute important macroelements in living organisms. They are also found in cell membranes, i.e., ensuring their stabilization or participating in synaptic transmission of nerve impulses. The aim of this work is to describe the interactions of divalent ions, such as Ca²⁺, Ba²⁺, and Sr²⁺, in electrolytes with the functional groups on the surface of liposomes formed from phosphatidylcholine (PC). Microelectrophoresis is used to determine the surface charge density as a function of pH. The interactions between ions found in solution and the functional groups of PC are described with the use of a seven-equilibrium mathematical model. Using this model along with experimental data on the charge density of the membrane surface, the association constants characterizing this equilibrium are determined. These parameters are used to calculate the theoretical model curves. The validity of the proposed model is confirmed by comparing the theoretically calculated changes in charge density on the liposome surface with the experimental results.

Synthesis and characterization of Barium-Iron containing magnetic bioactive glasses: The effect of magnetic component on structure and in vitro bioactivity

CaO-P₂O₅-SiO₂-BaO-Fe₂O₃ magnetic bioactive glasses were prepared via an optimized sol-gel method. This study is focused on investigating effects of magnetic content addition on the bioactive glass properties. To this aim, we evaluate the physical, rheological, and biocompatibility properties of synthesized magnetic bioactive glass. The morphology and composition of these glasses were studied using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). The particle size was also determined using Laser Particle Size Analyzer (LPSA). The thermal measurements were carried out using Differential Thermal Analysis (DTA). For assessing the in-vitro bioactive character of synthesized glasses, the ability for apatite formation on their surface upon immersion in simulated body fluid (SBF) was checked using SEM, EDX and pH measurements. Furthermore, the Ca, Si, Ba and Fe ions in SBF were monitored using Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). The results showed that the addition of Ba and Fe in the glass composition affect formation of apatite layer onto the glass surfaces. Morphologies of the apatite layers were also different in which the bioactivity decreased with increasing Fe concentration, but the increase of Ba concentration led to an increase in bioactivity. However all of the synthesized glasses are still highly bioactive. Finally, this research demonstrates that the synthesized magnetic bioactive glasses are nontoxic and biocompatible and they can be used as thermoseeds for cancer hyperthermia studies.

Rapid Dissolution of BaSO4 by Macropa, an 18-Membered Macrocycle with High Affinity for Ba2

Insoluble BaSO4 scale is a costly and time-consuming problem in the petroleum industry. Clearance of BaSO4-impeded pipelines requires chelating agents that can efficiently bind Ba2+, the largest nonradioactive +2 metal ion. Due to the poor affinity of currently available chelating agents for Ba2+, however, the dissolution of BaSO4 remains inefficient, requiring very basic solutions of ligands. In this study, we investigated three diaza-18-crown-6 macrocycles bearing different pendent arms for the chelation of Ba2+ and assessed their potential for dissolving BaSO4 scale. Remarkably, the bis-picolinate ligand macropa exhibits the highest affinity reported to date for Ba2+ at pH 7.4 (log K' = 10.74), forming a complex of significant kinetic stability with this large metal ion. Furthermore, the BaSO4 dissolution properties of macropa dramatically surpass those of the state-of-the-art ligands DTPA and DOTA. Using macropa, complete dissolution of a molar equivalent of BaSO4 is reached within 30 min at room temperature in pH 8 buffer, conditions under which DTPA and DOTA only achieve 40% dissolution of BaSO4. When further applied for the dissolution of natural barite, macropa also outperforms DTPA, showing that this ligand is potentially valuable for industrial processes. Collectively, this work demonstrates that macropa is a highly effective chelator for Ba2+ that can be applied for the remediation of BaSO4 scale.

Precursor Phenomena of Barium Titanate Single Crystals Grown Using a Solid-State Single Crystal Growth Method Studied with Inelastic Brillouin Light Scattering and Birefringence Measurements

The nature of precursor phenomena in the paraelectric phase of ferroelectrics is one of the main questions to be resolved from a fundamental point of view. Barium titanate (BaTiO₃) is one of the most representative perovskite-structured ferroelectrics intensively studied until now. The pretransitional behavior of BaTiO₃ single crystal grown using a solid-state crystal growth (SSCG) method was investigated for the first time and compared to previous results. There is no melting process in the SSCG method, thus the crystal grown using a SSCG method have inherent higher levels of impurity and defect concentrations, which is a good candidate for investigating the effect of crystal quality on the precursor phenomena. The acoustic, dielectric, and piezoelectric properties, as well as birefringence, of the SSCG-grown BaTiO₃ were examined over a wide temperature range. Especially, the acoustic phonon behavior was investigated in terms of Brillouin spectroscopy, which is a complementary technique to Raman spectroscopy. The obtained precursor anomalies of the SSCG-grown BaTiO₃ in the cubic phase were similar to those of other single crystals, in particular, of high-quality single crystal grown by top-seeded solution growth method. These results clearly indicate that the observed precursor phenomena are common and intrinsic effect irrespective of the crystal quality.

Better Resolution of High-Spin Cobalt Hyperfine at Low Frequency: Co-Doped Ba(Zn1/3Ta2/3)O₃ as a Model Complex

Low-frequency electron paramagnetic resonance (EPR) is used to extract the EPR parameter A-mid and support the approximate X-band value of g-mid for Ba(Co_yZn_1/3−yTa_2/3)O₃. Although the cobalt hyperfine structure for the |±1/2〉 state is often unresolved at X-band or S-band, it is resolved in measurements on this compound. This allows for detailed analysis of the molecular orbital for the |±1/2〉 state, which is often the ground state. Moreover, this work shows that the EPR parameters for Co substituted into Zn compounds give important insight into the properties of zinc binding sites.

A convenient identification of carbamate-derived drug substances

The "second identification" of drugs in pharmacies and hospital pharmacies affords the availability of easy to perform and robust tests. Besides determination of melting points and simple chromatography (TLC), reliable color and precipitation reactions are common techniques for this purpose. Preferentially, these reactions allow for the identification of typical functional groups in the drugs. Here we present a reaction for identification of carbamate-type drugs, based on the precipitation of barium carbonate upon treating the analytes with barium hydroxide solution at 80 °C. This method works well for carbamate drugs with noteworthy water solubility like carbachol, neostigmine bromide, and pyridostigmine bromide, and could be considered as a method for second identification of these drugs in pharmacopoeias and in Deutscher Arzneimittel-Codex/Neues Rezeptur-Formularium (DAC-NRF).

Selection of plants for phytoremediation of barium-polluted flooded soils

The use of barite (BaSO4) in drilling fluids for oil and gas activities makes barium a potential contaminant in case of spills onto flooded soils, where low redox conditions may increase barium sulfate solubility. In order to select plants able to remove barium in such scenarios, the following species were evaluated on barium phytoextraction capacity: Brachiaria arrecta, Cyperus papyrus, Eleocharis acutangula, E. interstincta, Nephrolepsis cf. rivularis, Oryza sativa IRGA 424, O. sativa BRS Tropical, Paspalum conspersum, and Typha domingensis. Plants were grown in pots and exposed to six barium concentrations: 0, 2.5, 5.0, 10.0, 30.0, and 65.0 mg kg^-1. To simulate flooding conditions, each pot was kept with a thin water film over the soil surface (∼1.0 cm). Plants were evaluated for biomass yield and barium removal. The highest amount of barium was observed in T. domingensis biomass, followed by C. papyrus. However, the latter exported most of the barium to the aerial part of the plant, especially at higher BaCl₂ doses, while the former accumulated barium preferentially in the roots. Thus, barium removal with C. papyrus could be achieved by simply harvesting aerial biomass. The high amounts of barium in T. domingensis and C. papyrus resulted from the combination of high barium concentration in plant tissues with high biomass production. These results make T. domingensis and C. papyrus potential candidates for phytoremediation schemes to remove barium from flooded soils.