Light curve analysis and evolutionary status of four newly identified short-period eclipsing binaries.

We present the physical and orbital parameters of four short-period eclipsing W UMa systems: [Formula: see text] (referred to as S1), [Formula: see text] (referred to as S2), [Formula: see text] (referred to as S3), and [Formula: see text] (referred to as S4). The absolute parameters and evolutionary status of these systems are determined, and new times of minima are calculated. Additionally, we present the 3D fill-out configuration for each system. The four Systems exhibit moderate contact W UMa binary with a fill-out factor of 49%, 38%, 28%, and 51%, respectively. Comparing the systems' periods, we observed a proportional relationship, where shorter periods correspond to lower fill-out factors, and longer periods were associated with higher fill-out factors. Based on the derived surface temperatures and mass ratios of the components, all systems are classified as A-type W UMa binaries. The obtained parameters in addition to a list of previously published data are then utilized to derive an updated Mass-Luminosity relation (M-L) for both A and W-type eclipsing W UMa systems. A comparison with previously published relations reveals that the majority of the EW systems lie between 0.2 and 2 Msun on the M-L diagram. Moreover, we discuss the dynamical evolutionary aspects and evolutionary status of the four components, along with their positions on the Zero Age Main Sequence (ZAMS) and Terminal Age Main Sequence (TAMS).

Functionalized iron oxide nanoparticles: synthesis through ultrasonic-assisted co-precipitation and performance as hyperthermic agents for biomedical applications.

Dual-functional iron oxide nanoparticles (IONPs), displaying self-heating and antibacterial effects are highly desired for biomedical application. This study involved the synthesis of functionalized IONPs coated with 3-aminopropyltriethoxysilane and polyethylene glycol via ultrasonic-assisted co-precipitation technique. The synthesized IONPs were then characterized by using Fourier-transform infrared spectroscopy, X-ray diffraction, dynamic light scattering, scanning electron microscopy, zeta potential, vibrating sample magnetometer and thermogravimetric analysis techniques. In addition, the effect of the synthesized IONPs on bacterial growth (S. aureus and E. coli) was studied. The influence of magnetic field power, as well as the viscous carriers on the heating efficiency of the synthesized IONPs was investigated. The specific absorption rate values increased as the power increased and decreased with the increase in the carrier viscosity. These characteristics render the synthesized iron oxide nanoparticles synthesized in the present study suitable for biomedical application as hyperthermic agents.

Polymeric Nanocomposites for Environmental and Industrial Applications.

Polymeric nanocomposites (PNC) have an outstanding potential for various applications as the integrated structure of the PNCs exhibits properties that none of its component materials individually possess. Moreover, it is possible to fabricate PNCs into desired shapes and sizes, which would enable controlling their properties, such as their surface area, magnetic behavior, optical properties, and catalytic activity. The low cost and light weight of PNCs have further contributed to their potential in various environmental and industrial applications. Stimuli-responsive nanocomposites are a subgroup of PNCs having a minimum of one promising chemical and physical property that may be controlled by or follow a stimulus response. Such outstanding properties and behaviors have extended the scope of application of these nanocomposites. The present review discusses the various methods of preparation available for PNCs, including in situ synthesis, solution mixing, melt blending, and electrospinning. In addition, various environmental and industrial applications of PNCs, including those in the fields of water treatment, electromagnetic shielding in aerospace applications, sensor devices, and food packaging, are outlined.

The Influence of Self-Heating Iron on the Thermal, Mechanical, and Swelling Properties of PDMS Composites for Organic Solvents Removal.

Volatile organic compounds pollute the environment and pose a serious threat to human health due to their toxicity, mutagenicity, and carcinogenicity. In this context, it is highly desirable to fabricate high-performance poly (dimethylsiloxane) (PDMS) composites to remove organic solvents from the environment using a simple technique. Therefore, in the present study, Fe-PDMS composites were fabricated using a technique based on magnetic induction heating with iron particles serving as a self-heating agent. Under an alternating magnetic field, the iron particles served as a thermal source that assisted in the progression of PDMS crosslinking. The influence of self-heating iron on the properties of the fabricated Fe-PDMS composites was also investigated. The hydrosilation reaction occurring during the crosslinking process was controlled using FT-IR. The heating efficiency of PDMS 1, PDMS 2, and PDMS 3 was studied as the function of induction time (0-5 min) and the function of iron content (0%, 1%, and 30% wt.%). The results revealed that the mechanical properties of the PDMS 2 composite were enhanced compared to those of the PDMS 1 and PDMS 3 composites. The mechanical properties of PDMS 3 were the least efficient due to cluster formation. PDMS 3 exhibited the highest thermal stability among all composites. Furthermore, the swelling behavior of different materials in various organic solvents was studied. PDMS was observed to swell to the greatest extent in chloroform, while swelling to a large extent was observed in toluene, pentane, and petroleum ether. PDMS swelling was the least in n-butanol. The elastomeric behavior of crosslinked PDMS, together with its magnetic character, produces stimuli-responsive magneto-rheological composites, which are quite efficient and suitable for applications involving the removal of organic solvents.

The Heating Efficiency and Imaging Performance of Magnesium Iron Oxide@tetramethyl Ammonium Hydroxide Nanoparticles for Biomedical Applications.

Multifunctional magnetic nanomaterials displaying high specific loss power (SLP) and high imaging sensitivity with good spatial resolution are highly desired in image-guided cancer therapy. Currently, commercial nanoparticles do not sufficiently provide such multifunctionality. For example, Resovist® has good image resolution but with a low SLP, whereas BNF® has a high SLP value with very low image resolution. In this study, hydrophilic magnesium iron oxide@tetramethyl ammonium hydroxide nanoparticles were prepared in two steps. First, hydrophobic magnesium iron oxide nanoparticles were fabricated using a thermal decomposition technique, followed by coating with tetramethyl ammonium hydroxide. The synthesized nanoparticles were characterized using XRD, DLS, TEM, zeta potential, UV-Vis spectroscopy, and VSM. The hyperthermia and imaging properties of the prepared nanoparticles were investigated and compared to the commercial nanoparticles. One-dimensional magnetic particle imaging indicated the good imaging resolution of our nanoparticles. Under the application of a magnetic field of frequency 614.4 kHz and strength 9.5 kA/m, nanoparticles generated heat with an SLP of 216.18 W/g, which is much higher than that of BNF (14 W/g). Thus, the prepared nanoparticles show promise as a novel dual-functional magnetic nanomaterial, enabling both high performance for hyperthermia and imaging functionality for diagnostic and therapeutic processes.

Increased production of hydrogen with in situ CO2 capture through the process of water splitting using magnetic core/shell structures as novel photocatalysts.

One of the chief challenges in hydrogen production through the photocatalytic splitting of water is to employ an efficient photocatalyst that has an absorption edge at the range of long wavelengths. In this study, composite structures made of different Ag-based shells over the core of Fe2O3 nanoparticles were utilized as novel magnetic photocatalysts for hydrogen generation from water. Specifically, Ag nanoparticles, Ag/(3-aminopropyl) triethoxysilane (APTS), and Ag/polyethyleneimine (PEI) were capped on the surface of the hematite core to produce three visible light-effective photocatalysts. Structural and textural properties of the synthesized photocatalysts were confirmed by Fourier transform infrared (FTIR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Additionally, their thermal stability and optical properties were respectively studied using thermogravimetric analysis (TGA) and UV reflectance. Photocatalytic activities of the presented core/shells were planned either as a function of the magnetic force or composition of the shell layer. It could be noted that the incorporation of organic or polymer layer could significantly increase the electronic density at the metal centers. Thus, the ability of iron oxide to catalyze the water-splitting process could be enhanced. Hence, the variation of shell structure could show a key-role in the photocatalytic potential of the presented structures in terms of manipulating the composition of produced gases. On the other hand, the magnetic nature of hematite could also positively affect the photocatalytic activity of these structures by minimizing the scattering of light irradiation during the splitting process. Particularly, shifting the way of photocatalysts dispersion from magnetic to mechanical (during water splitting) had in turn reduced hydrogen productivity from 540 to 485 mmol h-1 g-1. This obviously confirms the relationship between the level of hydrogen production by the presented photocatalysts and their magnetic nature which results in quenching of irradiation scattering.

Engineering Core-Shell Structures of Magnetic Ferrite Nanoparticles for High Hyperthermia Performance.

Magnetic ferrite nanoparticles (MFNs) with high heating efficiency are highly desirable for hyperthermia applications. As conventional MFNs usually show low heating efficiency with a lower specific loss power (SLP), extensive efforts to enhance the SLP of MFNs have been made by varying the particle compositions, sizes, and structures. In this study, we attempted to increase the SLP values by creating core-shell structures of MFNs. Accordingly, first we synthesized three different types of core ferrite nanoparticle of magnetite (mag), cobalt ferrite (cf) and zinc cobalt ferrite (zcf). Secondly, we synthesized eight bi-magnetic core-shell structured MFNs; Fe3O4@CoFe2O4 (mag@cf1, mag@cf2), CoFe2O4@Fe3O4 (cf@mag1, cf@mag2), Fe3O4@ZnCoFe2O4 (mag@zcf1, mag@zcf2), and ZnCoFe2O4@Fe3O4 (zcf@mag1, zcf@mag2), using a modified controlled co-precipitation process. SLP values of the prepared core-shell MFNs were investigated with respect to their compositions and core/shell dimensions while varying the applied magnetic field strength. Hyperthermia properties of the prepared core-shell MFNs were further compared to commercial magnetic nanoparticles under the safe limits of magnetic field parameters (<5 × 109 A/(m·s)). As a result, the highest SLP value (379.2 W/gmetal) was obtained for mag@zcf1, with a magnetic field strength of 50 kA/m and frequency of 97 kHz. On the other hand, the lowest SLP value (1.7 W/gmetal) was obtained for cf@mag1, with a magnetic field strength of 40 kA/m and frequency of 97 kHz. We also found that magnetic properties and thickness of the shell play critical roles in heating efficiency and hyperthermia performance. In conclusion, we successfully enhanced the SLP of MFNs by engineering their compositions and dimensions.

Synthesis of Magnetic Ferrite Nanoparticles with High Hyperthermia Performance via a Controlled Co-Precipitation Method.

Magnetic nanoparticles (MNPs) that exhibit high specific loss power (SLP) at lower metal content are highly desirable for hyperthermia applications. The conventional co-precipitation process has been widely employed for the synthesis of magnetic nanoparticles. However, their hyperthermia performance is often insufficient, which is considered as the main challenge to the development of practicable cancer treatments. In particular, ferrite MNPs have unique properties, such as a strong magnetocrystalline anisotropy, high coercivity, and moderate saturation magnetization, however their hyperthermia performance needs to be further improved. In this study, cobalt ferrite (CoFe2O4) and zinc cobalt ferrite nanoparticles (ZnCoFe2O4) were prepared to achieve high SLP values by modifying the conventional co-precipitation method. Our modified method, which allows for precursor material compositions (molar ratio of Fe+3:Fe+2:Co+2/Zn+2 of 3:2:1), is a simple, environmentally friendly, and low temperature process carried out in air at a maximum temperature of 60 °C, without the need for oxidizing or coating agents. The particles produced were characterized using multiple techniques, such as X-ray diffraction (XRD), dynamic light scattering (DLS), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-Vis spectroscopy), and a vibrating sample magnetometer (VSM). SLP values of the prepared nanoparticles were carefully evaluated as a function of time, magnetic field strength (30, 40, and 50 kA m-1), and the viscosity of the medium (water and glycerol), and compared to commercial magnetic nanoparticle materials under the same conditions. The cytotoxicity of the prepared nanoparticles by in vitro culture with NIH-3T3 fibroblasts exhibited good cytocompatibility up to 0.5 mg/mL. The safety limit of magnetic field parameters for SLP was tested. It did not exceed the 5 × 109 Am-1 s-1 threshold. A saturation temperature of 45 °C could be achieved. These nanoparticles, with minimal metal content, can ideally be used for in vivo hyperthermia applications, such as cancer treatments.

Controlled Preparation of Thermally Stable Fe-Poly(dimethylsiloxane) Composite by Magnetic Induction Heating.

The most challenging task in the preparation of poly(dimethylsiloxane) composites is to control the curing time as well as to enhance their thermal and swelling behavior. Curing rate can be modified and controlled by a range of iron powder contents to achieve a desired working time, where iron is used as self-heating particles. Iron under alternative current magnetic field (ACMF) is able to generate thermal energy, providing a benefit in accelerating the curing of composites. Three types of iron-Poly(dimethylsiloxane) (Fe-PDMS) composites were prepared under ACMF with iron content 5, 10, and 15 wt %. The curing process was investigated by FTIR, while the morphology and the thermal stability were examined by SEM, DMA, and TGA. The heating's profile was studied as functions of iron content and induction time. It was found that the time required to complete curing was reduced and the curing temperature was controlled by varying the iron content and induction time. In addition, the thermal stability and the swelling behavior of the prepared composites were enhanced in comparison with the conventional PDMS and thus offer a promising route to obtain thermally stable composites.

Magnetic Poly(N-isopropylacrylamide) Nanocomposites: Effect of Preparation Method on Antibacterial Properties.

The most challenging task in the preparation of magnetic poly(N-isopropylacrylamide) (Fe3O4-PNIPAAm) nanocomposites for bio-applications is to maximise their reactivity and stability. Emulsion polymerisation, in situ precipitation and physical addition were used to produce Fe3O4-PNIPAAm-1, Fe3O4-PNIPAAm-2 and Fe3O4-PNIPAAm-3, respectively. Their properties were characterised using scanning electron microscopy (morphology), zeta-potential (surface charge), thermogravimetric analysis (stability), vibrating sample magnetometry (magnetisation) and dynamic light scattering. Moreover, we investigated the antibacterial effect of each nanocomposite against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Both Fe3O4-PNIPAAm-1 and Fe3O4-PNIPAAm-2 nanocomposites displayed high thermal stability, zeta potential and magnetisation values, suggesting stable colloidal systems. Overall, the presence of Fe3O4-PNIPAAm nanocomposites, even at lower concentrations, caused significant damage to both E. coli and S. aureus DNA and led to a decrease in cell viability. Fe3O4-PNIPAAm-1 displayed a stronger antimicrobial effect against both bacterial strains than Fe3O4-PNIPAAm-2 and Fe3O4-PNIPAAm-3. Staphylococcus aureus was more sensitive than E. coli to all three magnetic PNIPAAm nanocomposites.

Study of Streptococcus thermophilus population on a world-wide and historical collection by a new MLST scheme.

We analyzed 178 Streptococcus thermophilus strains isolated from diverse products, from around the world, over a 60-year period with a new multilocus sequence typing (MLST) scheme. This collection included isolates from two traditional cheese-making sites with different starter-use practices, in sampling campaigns carried out over a three years period. The nucleotide diversity of the S. thermophilus population was limited, but 116 sequence types (ST) were identified. Phylogenetic analysis of the concatenated sequences of the six housekeeping genes revealed the existence of groups confirmed by eBURST analysis. Deeper analyses performed on 25 strains by CRISPR and whole-genome analysis showed that phylogenies obtained by MLST and whole-genome analysis were in agreement but differed from that inferred by CRISPR analysis. Strains isolated from traditional products could cluster in specific groups indicating their origin, but also be mixed in groups containing industrial starter strains. In the traditional cheese-making sites, we found that S. thermophilus persisted on dairy equipment, but that occasionally added starter strains may become dominant. It underlined the impact of starter use that may reshape S. thermophilus populations including in traditional products. This new MLST scheme thus provides a framework for analyses of S. thermophilus populations and the management of its biodiversity.

Dual-modality self-heating and antibacterial polymer-coated nanoparticles for magnetic hyperthermia.

Multifunctional nanoparticles for magnetic hyperthermia which simultaneously display antibacterial properties promise to decrease bacterial infections co-localized with cancers. Current methods synthesize such particles by multi-step procedures, and systematic comparisons of antibacterial properties between coatings, as well as measurements of specific absorption rate (SAR) during magnetic hyperthermia are lacking. Here we report the novel simple method for synthesis of magnetic nanoparticles with shells of oleic acid (OA), polyethyleneimine (PEI) and polyethyleneimine-methyl cellulose (PEI-mC). We compare their antibacterial properties against single gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria as well as biofilms. Magnetite nanoparticles (MNPs) with PEI-methyl cellulose were found to be most effective against both S. aureus and E. coli with concentration for 10% growth inhibition (EC10) of <150 mg/l. All the particles have high SAR and are effective for heat-generation in alternating magnetic fields.