Simultaneous Substitution Research Articles

Molecular aspects of oligomer-coupled ultra-small Au nanoparticles

In our quest for unlocking the growth mechanism of polymer stabilized metal nanostructures, we stumbled upon the solventless/templateless redox reaction between the monomer, N-vinyl pyrrolidone (NVP) and tetrachloroauric acid. This simple reaction results in the formation of oligomer-bridged ultra-small Au nanoparticles through an auto-catalyzed cluster aggregative nucleation process even under ambient conditions in the absence of any other external energy resources. Such intriguing, self-assembled nanostructures were beautifully illustrated through the TEM images, that are in strong correlation with the observed multiple optical absorption signatures. But, the sharp, intense peak at around 633 nm was quantified by quasi-static dipole model theoretical calculations as the predominantly coupled dimer peak, signifying the highly localized formation of small, cross-linked aggregates. Augmenting the same, the real time in vitro kinetic spectroscopic (such as FTIR, Raman, NMR etc.) measurements conveniently delineate, beyond doubt, the synergistic thermodynamic reaction mechanism as follows: the H+ ions from chloroauric acid react with NVP monomers and propagate via cross-linking, the diffusion rate of which kinetically diminish; the simultaneous square planar ligand substitution of the chloroaurate complexes with the carbonyl oxygen, not only annihilate the reaction sites, but also result in the disproportionate termination of cross-linked NVP oligomers, inter-dispersed with tiny metallic Au nanoparticles, stabilized through the aurophillic interactions. Further, the significance of NVP over other similar monomers were corroborated, thereby unleashing a molecular level understanding of the nanostructure-property functional relationship in a cohesive manner, for the development of unusual, unconventional methods of fabricating new smart materials with redefined application potentials.

Computational Peptide Engineering Approach for Selection the Best Engendered Camel Lactoferrin-Derive Peptide with Potency to Interact with DNA

Antimicrobial peptides (AMPs) are native and safe short peptides with valuable biological effects. Nowadays, these components and their importance have attracted the attention of many researchers to determine their mode of action. Computational peptide engineering can donate a useful insight for investigating the stability and potency of AMPs. In the present study, to improve the effect of CLF36, a chimeric peptide derived camel lactoferrin, the atomic insight into peptide-DNA interaction was analyzed using MD simulation. Targeted mutants were performed in wild type amino acid sequences and obtained engineered peptides were homology modeled for peptide-DNA interaction analysis. SASA, Hydrogen binding and free binding energy analyses revealed that all changes in wild type of peptide in this study improved the peptide-DNA interaction. Our in silico results showed that simultaneous substitution of GLU12 with ALA and also removing SER36 in wild type had more substantial effects on complex formation with DNA. The obtained result of this study could be useful to improve the stability and potency of engineered peptides to use of in the experimental study.

Metastable equilibrium of substitution reactions among oxygen- and nitrogen-bearing organic compounds at hydrothermal conditions

Measured abundances of organic compounds can reveal information about the environments in which they formed. Since organic compounds can be mobilized and released from geologic and planetary settings, they have the potential to provide insights into environments that are difficult to observe directly. To advance our understanding of these environments, this study identifies organic reactions that approach metastable equilibrium in experiments, so that future studies can predict geochemical conditions in remote settings (e.g., deep Earth, extraterrestrial bodies) by monitoring reaction ratios of compounds involved in similar organic reactions. At high temperatures organic redox reactions can equilibrate, which allows comparisons with thermodynamic properties to yield estimates of reaction conditions. However, redox reactions may equilibrate too slowly to be applicable to lower temperature systems. To explore metastable equilibria at lower temperatures, we studied substitution reactions that tend to be faster than redox reactions. In this study, we demonstrate that oxygen- and nitrogen-bearing organic compounds at hydrothermal conditions undergo a series of simultaneous substitution reactions that rapidly approach steady-state ratios indicative of metastable equilibrium. Four sets of aqueous experiments were performed at 250 °C and 40 bar, each beginning with a single organic reactant: benzyl alcohol, benzylamine, dibenzylamine, or tribenzylamine. All reactant solutions were prepared with identical bulk elemental compositions by adjusting the concentrations of the starting organic compounds and adding ammonia as needed. After 2 h at hydrothermal reaction conditions, all of the model compounds were detectable in all four sets of experiments, evidence for reversibility of reactions among the compounds. After 72 h, reaction ratios between the model compounds converged in all four sets of experiments, consistent with approaches toward metastable equilibrium. Reaction ratios for ether and aldehyde formation reactions were also observed to group within a relatively small range, but without a clear convergence pattern, suggesting other non-redox reactions may approach metastable equilibrium. The approach to metastable equilibrium among the initial organic reactants could be observed and quantified even in the presence of competing redox reactions whose mechanisms are less understood, including dibenzylimine and toluene formation, which did not appear to reach steady-states. These findings identify classes of organic compounds and reactions that can reflect the conditions at which they last equilibrated and should be targeted for analysis in natural systems.

Precise control of density and strength of acid sites of MFI-type zeolite nanoparticles via simultaneous isomorphous substitution by Al and Fe

The co-incorporation of Al and Fe at various relative ratios into the MFI-type zeolite framework enabled linear control of the density and strength of acid sites, and such well-tuned acidity led to a better catalyst lifetime.

ТРАНСФОРМАЦИЯ ВОСПРОИЗВОДСТВЕННЫХ ПРОЦЕССОВ В СЕЛЬСКОМ ХОЗЯЙСТВЕ

In the era of accelerating transformations and the coronavirus pandemic, to ensure the national food security, preserve the share of the rural population, increase the disposable resources of rural households and exports of agricultural products with simultaneous import substitution, systemic changes are required. For this purpose, it is necessary to renew all elements of the reproductive process in the agricultural industry (production, distribution, exchange and consumption) and develop a strategic trajectory for the agricultural industry. Whether this crisis will eliminate structural contradictions of the existing model of social reproduction depends on various factors determined by the government policy. The government should manage the reproduction processes in the agricultural industry. It can create a need for deep theoretical understanding and changes in the reproduction processes.

Role of simultaneous substitution of Cu2+ and Mn2+ in ZnS thin films: Defects-induced enhanced room temperature ferromagnetism and photoluminescence

In this study, we have synthesized Mn2+ and Cu2+ co-substituted ZnS thin films by chemical solution process. The role of the Cu2+ substitution levels (1, 3, 5 and 10%) on the structural, optical, photoluminescence and magnetic properties of Zn0.95Mn0.05S thin films has been investigated. The results show a ZnS-like hexagonal wurtzite structure without any secondary phases is successfully obtained. A relatively dense, homogeneous film surfaces with increased grain size by increment of Cu2+ substitution level are observed. The presence of Zn2+, Cu2+, Mn2+, S2− and incorporation of the Mn2+, Cu2+ within host ZnS are evidenced. With increasing the Cu2+ substitution level, the optical band gap energy has reduced. Near band (347–369 nm), blue (418–422 nm), green (525–545 nm) and yellow-orange (590–609) emissions have been detected. The origin of enhancement in room temperature ferromagnetism are attributed to the combined effect of the defects and super exchange mechanism. It is expected that the synthesized films will find a wide applications in fabrication of spintronic, magnetic, optoelectronic and phosphor nano devices.

Adenine·cytosine substitutions are an alternative pathway of compensatory mutation in angiosperm ITS2.

Compensatory mutations are crucial for functional RNA because they maintain RNA configuration and thus function. Compensatory mutation has traditionally been considered to be a two-step substitution through the GU-base-pair intermediate. We tested for an alternative AC-mediated compensatory mutation (ACCM). We investigated ACCMs by using a comprehensive sampling of ribosomal internal transcribed spacer 2 (ITS2) from 3934 angiosperm species in 80 genera and 55 families. We predicted ITS2 consensus secondary structures by using LocARNA for structure-based alignment and partitioning paired and unpaired regions. We examined and compared the substitution rates and frequencies among base pairs by using RNA-specific models. Base-pair states of ACCMs were mapped onto the inferred phylogenetic trees to infer their evolution. All types of compensatory mutations involving the AC intermediate were observed, but the most frequent substitutions were with AU or GC pairs, which are part of the AU–AC–GC pathway. Compared with the GU intermediate, AC had a lower frequency and higher mutability. Within the AU–AC–GC pathway, the AU–AC substitution rate was much slower than the AC–GC substitution rate. No consistently higher overall rate was identified for either pathway among all 80 sampled lineages, though compensatory mutations through the AC intermediate averaged about half that through the GU intermediate. These results demonstrate an alternative compensatory mutation between AU and GC that helps address the controversial inference of inferred simultaneous double substitutions.

An improved overlap extension PCR for simultaneous multiple sites large fragments insertion, deletion and substitution

The existing molecular cloning methods are often limited by the availability of suitable restriction sites. It is still a challenge for simultaneous cloning of multiple fragments into different sites of a single vector. Here we developed a novel method named improved overlap extension PCR (IOEP) for restriction enzyme independent cloning of large fragments. The addition of primers enables IOEP to exponentially amplify the overlap extension product, thus greatly improves the amplification efficiency of large fragments. Moreover, coupled with the benefit of T4 DNA polymerase to improve cloning efficiency, our method can be used to simultaneously insert, delete and replace multiple DNA fragments at different sites.

Study of combined effect of partial Bi doping and particle size reduction on magnetism of La0.7Sr0.3MnO3

La0.7Sr0.3MnO3 has been subjected to simultaneous partial bismuth substitution and particle size reduction to understand the mechanism controlling the magnetic properties. Nanosized samples of 10% Bi doped La0.7Sr0.3MnO3 samples were prepared by high energy planetary ball milling. Compared to pristine La0.7Sr0.3MnO3, 10% Bi doping results in the reduction of saturated magnetic moment and Curie temperature. Using the ‘top-down approach’ through high energy planetary ball milling, particle size reduces from 250 nm for bulk to 26 nm for 48 h ball milled sample. Correspondingly, the magnetic properties show the direct influence of size reduction, as the observed magnetic moment shows drastic decrease as particle size reduces. It is interesting to note that 10% Bi doping in La0.7Sr0.3MnO3 plays important role in controlling the size with respect to milling time. In the present work, we discuss the magnetic properties of nanostructured La0.6Bi0.1Sr0.3MnO3 samples. The observed magnetization behaviour can be described using the core-shell model for nanoparticles.

IsCT-based analogs intending better biological activity.

IsCT1-NH2 is a cationic antimicrobial peptide isolated from the venom of the scorpion Opisthacanthus madagascariensis that has a tendency to form an α-helical structure and shows potent antimicrobial activity and also inopportunely shows hemolytic effects. In this study, five IsCT1 (ILGKIWEGIKSLF)-based analogs with amino acid modifications at positions 1, 3, 5, or 8 and one analog with three simultaneous substitutions at the 1, 5, and 8 positions were designed. The net charge of each analog was between +2 and +3. The peptides obtained were characterized by mass spectrometry and analyzed by circular dichroism for their structure in different media. Studies of antimicrobial activity, hemolytic activity, and stability against proteases were also carried out. Peptides with a substitution at position 3 or 5 ([L]3 -IsCT1-NH2 , [K]3 -IsCT1-NH2 , or [F]5 -IsCT1-NH2 ) showed no significant change in an activity relative to IsCT1-NH2 . The addition of a proline residue at position 8 ([P]8 -IsCT1-NH2 ) reduced the hemolytic activity as well as the antimicrobial activity (MIC ranging 3.13-50 μmol L-1 ), and the addition of a tryptophan residue at position 1 ([W]1 -IsCT1-NH2 ) increased the hemolytic activity (MHC = 1.56 μmol L-1 ) without an improvement in antimicrobial activity. The analog [A]1 [F]5 [K]8 -IsCT1-NH2 , which carries three simultaneous modifications, presented increasing or equivalent values in antimicrobial activity (MIC approximately 0.38 and 12.5 μmol L-1 ) with a reduction in hemolytic activity. In addition, this analog presented the best resistance against proteases. This kind of strategy can find functional hotspots in peptide molecules in an attempt to generate novel potent peptide antibiotics.

Improved activity and expression of recombinant human factor IX by propeptide engineering.

The main therapeutic strategy for Hemophilia B patients involves the administration of recombinant coagulation factors IX (rFIX). Although there are various approaches to increasing the activity of rFIX, targeted protein engineering of specific residues could result in increased rFIX activity through enhanced γ-carboxylation. Specific amino acids in the propeptide sequence of vitamin K-dependent proteins are known to play a role in the interaction with the enzyme γ-carboxylase. The net hydrophobicity and charge of the γ-carboxylic recognition site (γ-CRS) region in the propeptide are important determinants of γ-carboxylase binding. Sothe contribution of individual γ-CRS residues to the expression of fully γ-carboxylated and active FIX was studied. Propeptide residues at positions -14, -13, or - 12 were substituted for equivalent prothrombin amino acids by SEOing PCR. The recombinant FIX variants were transfected and stably expressed in Drosophila S2 cells, and the expression of both total FIX protein and active FIX was assessed. While overall the substitutions resulted in an increase of both total FIX protein expression as well as an increase in the portion of active FIX, the highest increase in FIX protein expression, FIX activity, and specific FIX activity was observed following the simultaneous substitution of residues at positions -12, -13, and - 14. The enhanced rFIX activity was further confirmed by enrichment for functional, fully γ-carboxylated rFIX species via barium citrate adsorption. Our findings indicate that by increasing both the net charge and the net hydrophobicity of the FIX γ-CRS region, the expression of fully γ-carboxylated and as such active FIX is enhanced. Graphical abstract .

Facile preparation of fluorescent nanodiamond based polymer nanoparticles via ring-opening polymerization and their biological imaging.

Fluorescent nanodiamond (ND) has been regarded as one of the most promising fluorescent nanoprobes owing to their chemical inert, biocompatibility, optical properties, and rich surface chemistry. The fluorescent ND has been mainly fabricated through high-energy ion beam irradiation of type Ib diamonds and subsequent thermal annealing. The generation of nitrogen-vacancy centers is the reason for the fluorescence. However, the physical method is relatively complicated and it need to expensive equipment as well as high cost. On the other hand, the resultant fluorescent ND particles are lack of functional groups and difficult to be dispersed in aqueous solution. Therefore, the development of facile methods to direct preparation of fluorescent ND and surface modification with functional polymers is of great research interest for expanding the biomedical applications of fluorescent ND. In this report, a facile strategy was reported for the first time to prepare hydrophilic polymers functionalized fluorescent ND (named as ND-PhE-PETOx) composites through the ring-opening polymerization and simultaneous simple nucleophilic substitution reaction using the non-fluorescent detonation ND as the raw material. The obtained fluorescent ND composites were characterized by various characterization techniques in details. The as-obtained ND-PhE-PETOx composites exhibit high water dispersibility, low toxicity and strong fluorescence intensity. Cell uptake results indicating that the fluorescent ND based composites can be effectively internalized by cells. Taken together, we have developed a novel and simple method for the preparation of fluorescent ND based composites, which show excellent physicochemical properties and great potential for biomedical applications.

Amphotericity-spectroscopy correlations in Eu doped sodium bismuth titanate (Na0.5Bi0.5TiO3)

Optical characteristics of a doped material depend on the site wherein the dopant resides. In mixed A-site perovskites, the dopant has several possibilities. This, in turn, correlates with the emission spectrum of the doped material. Here we choose Eu3+ as the dopant since it is a well-known and efficient red-luminophore. Sodium bismuth titanate (NBT-Na0.5Bi0.5TiO3) is selected as a host due to its ability to accommodate Eu over large concentration windows while maintaining optical activity. For compositions x ≥ 0.04, we show that Eux:NBT has amphoteric behavior (i.e., simultaneous dopant substitution in two competing sites). Eu3+ occupancy in Bi and Ti-sites are quantitatively estimated using Rietveld refinement. Also, the appearance of A1g breathing vibrational mode (830–860 cm−1) in Raman spectra shows the presence of Eu3+ on the Ti-site. Photoluminescence (PL) emission shows sharp and intense bands at ∼592 nm, ∼615 nm, and ∼687 nm, and one weak band at ∼652 nm, corresponding to f–f transitions of Eu3+. To evaluate the optical characteristics with varying site-substitution of Eu3+; Judd–Ofelt parameters and radiative properties are calculated for the first time in this mixed A-site titanate system. From the values of asymmetric ratios; Eu3+ ion is shown to occupy the non-centrosymmetrical sites (Bi-sites) of NBT. However, at x = 0.04, Ω2 < Ω4, which indicates long-range effects and hence Eu occupancy in centrosymmetric sites (Ti-sites). This study opens up avenues for further exploration of correlations between dopant-concentration, amphotericity, and spectrochemical response in other systems. The amphoteric behavior of dopants can tune emission intensities and produce multi-emission colors using a single-dopant. This would have implications for luminescence-based applications.

Contrasting anion disorder behavior in Sm2Zr2O7 by simultaneous aliovalent cation substitutions and its structural and electrical properties

In the present study, the effect of simultaneous aliovalent cation substitutions on the B site of the pyrochlore type compositions has been studied to understand the anion disorder and its influence on the electrical properties. In this regard, the Sm2Zr2 – x(YNb)x/2O7 (x = 0, 0.25, 0.5, 0.75, 1) compositions were prepared via solid-state reaction route, and the structural and electrical properties of the prepared compositions were analyzed using advanced techniques. The structural analysis studies reveal that the concentration of aliovalent cation substitution has a distinct effect on the structure; the lower concentration of Y and Nb (x ≤ 0.25) destabilizes the system, lowering the distortion, and at higher concentrations (x ≥ 0.5), it stabilizes the system. As a consequence, the distortion of BO6 increases at higher substitutions; thus, the lattice strain of the system increases, manifesting the higher anion disorder in the system. The degree of the anion disorder is further evaluated by the intensity ratio of the Raman intense Eg mode and the T2g mode around 800 cm−1 from the Raman spectrum whose trend is in line with the oxygen x-parameter variation with different concentrations of the aliovalent cation substitution. The electrical properties follow the same trend of the anion disorder and the lattice strain in the system. The maximum conductivity of 4.44 × 10−4 S/cm is obtained for the composition (x = 1) having the maximum anion disorder and lattice strain. The present study demonstrates the interrelationship among the lattice strain, anion disorder, and oxide ion conductivity, which will be helpful in designing and developing new oxide ionic conductors.

The unusual suppression of superconducting transition temperature in double-doping 2H-NbSe2

2H-NbSe2 is one of the most widely researched transition metal dichalcogenide (TMD) superconductors, which undergoes charge-density wave (CDW) transition at TCDW about 33 K and superconducting transition at Tc of 7.3 K. To explore the relation between its superconductivity and Fermi surface nesting, we have combined S substitution with Cu intercalation in 2H-NbSe2 to make CuxNbSe2−ySy (0 ≤ x = y ≤ 0.1). Upon systematic substitution of S and intercalation of Cu ions into 2H-NbSe2, we found that when the Cu and S contents (x = y ≥ 0.06) increase, the Tc decreases in CuxNbSe2−ySy. At higher x and y values, Tc keeps a constant value near 2 K, which is not commonly observed for a layered TMD. For comparison, we found that the simultaneous substitution of Nb by Cu and Se by S in CuxNb1−xSe2−ySy (0 ≤ x = y ≤ 0.06) lowered the Tc substantially faster. We constructed superconducting phase diagrams for our double-doping compounds in contrast with the related single-ion doping systems.

Arg-8 of yeast subunit e contributes to the stability of F-ATP synthase dimers and to the generation of the full-conductance mitochondrial megachannel

The mitochondrial F-ATP synthase is a complex molecular motor arranged in V-shaped dimers that is responsible for most cellular ATP synthesis in aerobic conditions. In the yeast F-ATP synthase, subunits e and g of the FO sector constitute a lateral domain, which is required for dimer stability and cristae formation. Here, by using site-directed mutagenesis, we identified Arg-8 of subunit e as a critical residue in mediating interactions between subunits e and g, most likely through an interaction with Glu-83 of subunit g. Consistent with this hypothesis, (i) the substitution of Arg-8 in subunit e (eArg-8) with Ala or Glu or of Glu-83 in subunit g (gGlu-83) with Ala or Lys destabilized the digitonin-extracted F-ATP synthase, resulting in decreased dimer formation as revealed by blue-native electrophoresis; and (ii) simultaneous substitution of eArg-8 with Glu and of gGlu-83 with Lys rescued digitonin-stable F-ATP synthase dimers. When tested in lipid bilayers for generation of Ca2+-dependent channels, WT dimers displayed the high-conductance channel activity expected for the mitochondrial megachannel/permeability transition pore, whereas dimers obtained at low digitonin concentrations from the Arg-8 variants displayed currents of strikingly small conductance. Remarkably, double replacement of eArg-8 with Glu and of gGlu-83 with Lys restored high-conductance channels indistinguishable from those seen in WT enzymes. These findings suggest that the interaction of subunit e with subunit g is important for generation of the full-conductance megachannel from F-ATP synthase.

Impacts of an Increased Substitution of Fossil Energy Carriers with Electricity-Based Technologies on the Swiss Electricity System

Electrifying the energy system with heat pumps and battery electric vehicles (BEV) is a strategy of Switzerland and many other countries to reduce CO2 emissions. A large electrification, however, poses several new challenges for the electricity system, particularly in combination with a simultaneous substitution of nuclear power plants (NPP) by volatile renewables such as photovoltaics (PV). In this study, these challenges in terms of additional electricity demands, deficits and surpluses as well as effective CO2 mitigation are assessed in a dynamic and data-driven approach. To this end, electricity demand and production profiles are synthesized based on measured data and specifications and assumptions of the key technologies at a high temporal resolution. The additional electricity demand of heat pumps is estimated from hourly measured heat demand profiles of a Swiss district heating provider, while for BEV different recharging patterns are combined. For electricity production, NPP are deducted from the current electricity production profile, while PV is added at an hourly resolution. In order to estimate CO2 emissions, life-cycle analysis (LCA) CO2 intensities of the different technologies are used. It is shown that with a BEV and heat pump penetration of 20% and 75%, respectively, there is an almost 25% (13.7 TWh/year) increase of the electricity demand and—just as challenging—an additional maximum power requirement of 5.9 GWh/h (hourly-averaged power). Without additional storage options, large amounts of electricity must be imported in winter and at night, while in summer at noon there is a large surplus from PV. Due to their high CO2 intensities—at least for the next decades—electricity imports and PV may—depending on the reference scenario (with or without NPP) and assumptions on other key parameters—even offset the overall CO2 savings of a highly electrified Swiss energy system.

Ce–Nd Co-substituted nanospinel cobalt ferrites: An investigation of their structural, magnetic, optical, and apoptotic properties

Abstract In this study, Nd3+ and Ce3+ co-substituted Co ferrite nanoparticles (NPs) were prepared using a sonochemical approach. The simultaneous substitution of Nd3+ and Ce3+ into CoFe2O4 nanoparticles (NPs) affected the structure, magnetic properties, and cation distribution. The structural parameters were investigated and calculated via XRD studies. The nanocrystalline morphology was identified by SEM along with EDX and TEM. The appearance of two vibration bands correlated to the Td and Oh group relevant to the spinel ferrite lattice were confirmed by Fourier-transform infrared spectroscopy (FT-IR). Magnetization analyses were conducted at room temperature (300K; RT) and low (10K) temperatures. Different magnetic parameters including the remanence (Mr), coercivity (Hc), saturation magnetization (Ms), squareness ratio (SQR = Mr/Ms), and magnetic moment ( n B ) were deduced and discussed. The results demonstrated a superparamagnetic (SPM) nature in the x = 0.00 sample at RT. However, the other samples (0.03 ≤ x ≤ 0.20) exhibited ferromagnetic (FM) natures. At 10K, all of the synthesized NPs displayed FM behavior. An enhancement in the Mr, Ms, Hc, and n B was detected at lower Nd3+ and Ce3+ concentrations (x ≤ 0.10). The SQR values at RT were smaller than 0.5, indicating a single domain nature with uniaxial anisotropy in all of the produced ferrites. However, the SQR values were in a range of 0.687–0.769 at 10K, suggesting a multi-magnetic domain at low temperatures. This study also examined the impact of Nd3+- and Ce3+-doped cobalt ferrite nanoparticles on human colon cancer cells (HCT-116) to examine their anti-cancer properties using MTT and morphometric assays. After 48 h of treatment with an optimal dose of Nd3+ and Ce3+, the doped cobalt ferrite nanoparticles demonstrated significant apoptotic effects by decreasing cancer cell viability in a dose-dependent manner. These results could lead to the use of NPs as a drug-screening/potential therapeutic strategy targeting human colorectal cancer.

The influence of simultaneous divalent cations (Mg2+, Co2+ and Sr2+) substitution on the physico-chemical properties of carbonated hydroxyapatite

Bone is generally known as calcium-apatite which contains considerable amounts of various trace elements, mainly carbonate. Thus, bone is usually referred as carbonated hydroxyapatite (CHA). The incorporation of dopants into calcium-apatite has been proposed. This approach provides a safer and efficient platform for enhancing bone remodelling. However, reports that emphasize on the influence of multi-dopant substitutions into the CHA structure particularly in the form of as-synthesized powders are limitedly available. The present study investigates the influence of simultaneous substitution of divalent cations, Mg2+, Co2+ and Sr2+ into CHA structure by a nanoemulsion method. Several combinations of ions were doped into the CHA structure. The XRD and FTIR results confirmed that the phase purity and crystallinity were not affected by the simultaneous incorporation of multi-doped ions; all powders remained as amorphous B-type CHA. Despite the small amount of dopants used, all the three cations were successfully substituted into the Ca2+ site of CHA structure. The crystallite size of the as-synthesized powder decreased as the amount of incorporated dopants increased. Interestingly, the particle shape showed the transformation from near spherical structures into needle-like structures with increasing amount of dopants. Our finding highlights that the incorporation of these cations into the CHA structure results in crystal imperfections, which cause a substantial dislocation of the crystal lattice, as seen by the alteration of the lattice parameters, crystallite and particle sizes of the as-synthesized powders.

Tuning nature and temperature of structural and magnetic phase transitions of [formula omitted] (M=Ag, Ni)

Antiperovskite materials based on Mn3CuN with Cu partially replaced by Ag or Ni and simultaneous substitution of N by C were synthesized and their magneto-structural transition was studied. By replacing Cu partially with Ag or Ni, Curie temperatures increase, the magnetostructural transition becomes isosymmetric and presents a more second order character. Simultaneous replacement of N by C reverses this trend as the Curie temperature decreases with increasing Ag/Ni content while the structural transition remains non-isosymmetric. Additionally, moderate magnetocaloric effects with magnetic entropy changes around 6 J/Kkg in the range of 130–150 K at a 2 T field change are observed. Finally, the influence of the change in number of valence electrons and cell size by substitution on the transition is discussed.