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Hydroxyapatite is a biocompatible material with various applications. To meet the demand for industrial use of this material, a rapid and upscalable process for the synthesis of hydroxyapatite nanoparticles was developed using an in-house developed two-stage continuous flow hydrothermal reactor. In the framework of this study, phase pure and highly crystalline 30 to 115 nm long hydroxyapatite nanorods were produced for potential use as nanofertilizers. The phase composition of the nanorods was confirmed by X-ray diffraction. Particle size and shape were investigated using transmission electron microscopy. Inductively coupled plasma mass spectrometry was used to determine the Ca:P ratio. It was shown that the use of a second mixing stage allows the particle length to be decreased down to 30 nm without compromising on crystallinity. In addition to using different mixing stages, adjusting the pH and controlling the flow speed allow wide range size tuning of the produced particles. The experimental setup allows for continuous synthesis of phase pure and highly crystalline hydroxyapatite nanorods, ensuring the reproducibility and scalability of the process. Dispersive behavior and dissolution in citrate buffer at a hydroponic pH of 5.5 were studied to evaluate further possibilities of applying produced NPs on the plants.

Over the past several decades, major efforts have been directed toward the optimization of carrier concentrations to maximize thermoelectric performance. Chemical doping is an effective way to control carriers, but electrostatic gating provides a continuous tuning knob that enables effective and dynamic changes to the carrier density. Here, a method is reported that uses an electric-double-layer (EDL) transistor-based ionic liquids gating to adjust the thermoelectric properties of thin films made from Nb-doped SrTiO3 (Nb-STO). This technique allows us to effectively change these properties at room temperature by varying the concentration of charge carriers within a broad range. A combination of lower film thickness and intrinsic carrier concentration leads to an enhanced ionic liquid-gated response, resulting in an 18-fold enhancement in power factor at room temperature for a 14 nm thin 4% Nb-STO film at gate voltages within ±3.0 V. The present study offers new insights and strategies toward enhanced gate tunable thermoelectric properties in thin films.

The present disclosure relates to a method of manufacturing a wire comprising MgB2 wire, where the method comprises the following steps, (a) providing a substantially tubular component having a lengthwise cavity, the tubular component being provided as a preform comprising compacted amorphous Boron powder, (b) providing a Magnesium-comprising component, (c) forming a composite billet by inserting the Magnesium-comprising component into the cavity of the tubular component, and by inserting the tubular component into an outer container such that the outer container surrounds the first tubular component, (d) performing a plastic deformation treatment of the composite billet to produce a deformed wire having a cross-section with predetermined wire cross-section dimension(s), (e) heating the deformed wire by thermal treatment to a temperature above the melting point of Mg.

We present triple-axis neutron scattering studies of low-energy magnetic fluctuations in strongly underdoped La2−xSrxCuO4 with x = 0.05, 0.06 and 0.07, providing quantitative evidence for a direct competition between these fluctuations and superconductivity. At dopings x = 0.06 and x = 0.07, three-dimensional superconductivity is found, while only a very weak signature of twodimensional superconductivity residing in the CuO2 planes is detectable for x = 0.05. We find a surprising suppression of the low-energy fluctuations by an external magnetic field at all three dopings. This implies that the response of two-dimensional superconductivity to a magnetic field is similar to that of a bulk superconductor. Our results provide direct evidence of a very gradual onset of superconductivity in cuprates.

Foliar application of nanofertilizers is currently regarded as a promising alternative to conventional soil fertilization. For successful development of nanofertilizers, firstly, a better understanding of interactions of nanoparticles with the leaf surface is needed. In the framework of this study a globally available cereal grain Hordeum Vulgare (barley) was chosen as model plant. Gold nanoparticles (Au NPs) were chosen as model particles for foliar application. Two synthesis methods were used: established photoreduction with citric acid and phytochemical synthesis using Aegopodium Podagraria (ground elder) extract. In both cases the reducing agent was acting also as surface stabilizer. Au NPs formation was confirmed by UV-VIS spectroscopy. To our knowledge it is the first time A. Podagraria extract was used for Au NPs synthesis. The morphology of the produced particles was characterized by transmission electron microscopy (TEM). The interaction of Au NPs with the adaxial side of barley leaves was studied by low-vacuum scanning electron microscopy (SEM). It was established that citrate stabilized Au NPs agglomerates evenly distribute in droplet-leaf contact areas avoiding stomates. Plant extract stabilized Au NPs form a film in the contact areas and accumulate on all leaf parts - stomates, trichomes and lamina. It was shown that Au NPs produced via green phytochemical synthesis have improved interaction with the leaf surface of barley.

We present triple-axis neutron scattering studies of static and dynamic magnetic stripes in an optimally oxygen-doped cuprate superconductor, La2CuO4+y, which exhibits a clean superconducting transition at Tc=42K. Polarization analysis reveals that the magnetic stripe structure is equally represented along both of the tetragonal crystal axes and that the fluctuating stripes display significant weight for in-plane as well as out-of-plane spin components. Both static magnetic order as well as low-energy fluctuations are fully developed in zero applied magnetic field and the low-energy spin fluctuations at ω=0.3-10meV intensify on cooling. We interpret this as an indication that superconductivity and low-energy spin fluctuations coexist microscopically in spatial regions which are separated from domains with static magnetic order.

We report on the response of a monolithic high $\mathrm{T_{c}}$ transition-edge bolometer to about 3-mm-wave for the first time. The detector structure consisting of 400 nm $\mathrm{YBa_{2}Cu_{3}O_{7-x}}$ (YBCO) film on buffered Yttria Stabilized Zirconia substrate without any coupled antenna, shows bolometric type responsivity to the 3-mm-waves radiation at its transition temperature. The YBCO thin film and $\mathrm{Ce_{0.9}La_{0.1}O_{2}}$ buffer layer are both fabricated by the metal-organic deposition method. The meander line pattern of the bolometer is designed for obtaining maximum absorption and responsivity possible when the polarized radiation of the source is aligned with the pattern. Meander lines are 50 micrometers wide and 1.5 mm long. We have measured amplitude and phase of the response versus modulation frequency of the detector to the linearly polarized 95 GHz source, and the detector was biased at 5 distinct temperatures at the transition corresponding to five different electrical conductivities of the YBCO film. When the meander lines of the device are parallel to the incident beam polarization, the YBCO pattern is speculated to act as a dissipative antenna resulting in higher absorption leading to high magnitude of the response as observed. The results from the measured phase of the response versus modulation frequency are also in agreement with the discussed absorbed mechanism. The absorption of the YBCO pattern is also measured to depend on the electrical conductivity of the YBCO film and our results show that there is an optimum electrical conductivity for having maximum absorption for this detector. Simulation results for this structure confirm the experiments showing that at electrical conductivity value of $\mathrm{1.33\times10^{5}}$ S/m we have the maximum absorption for our device. These observations promise design of versatile THz and millimeter-wave detectors with potentials for applications in medical and security imaging.

In spite of many years of research, the physical phenomena leading to the evolution of compacted graphite (CG) during solidification is still not fully understood. In particular, it is unknown how highly branched CG aggregates form and evolve in the semi-solid, and how local microstructural variations at micrometer length scale affect this growth process. We present here the first time-resolved synchrotron tomography combined with a bespoke high-temperature environmental cell that allows direct observation of the evolution of CG and relates this dynamic process to the local surrounding microstructures in a cast iron sample during repeated melting and solidification. Distinct processes are identified for the formation of CG involving the nucleation, growth, development of branches and interconnection of graphite particles, ultimately evolving into highly branched graphite aggregates with large sizes and low sphericities. CG is found to nucleate with a spheroidal or a plate-like shape, developing branches induced by high carbon concentration, e.g. thin melt channels. Additionally, CG grows much faster than spheroidal graphite during subsequent cooling in solid state. The direct visualization of the dynamic solidification process provides unprecedented new insights into formation mechanisms of CG and correlating factors such as local microstructural variations, and guides the development of CG iron solidification models.

Inelastic neutron scattering has been used to study the in-plane Cu-O bond-stretching mode in oxygendoped La1.94Sr0.06CuO4.035 (T-c = 38 K) and La2CuO4+delta (T-c = 43 K). Similar to results from optimally doped La1.85Sr0.15CuO4 (T-c = 35 K), we observe anomalous features in the dispersion of this half-breathing mode in the form of a softening halfway through the Brillouin zone. Considering the differences in electronic structure and local environment between the oxygen- and strontium-doped compounds with similar T-c, we rule out a connection between the phonon anomaly and structural instabilities related to the specific dopant type. We interpret the phonon anomaly as a signature of correlated charge fluctuations ubiquitous in optimally doped superconductors.

Carbon-doped MgB2 polycrystalline bulk samples were prepared by reacting mixtures of Mg and B powders, with and without 0.5 wt.% of the amino acids glycine, alanine, valine, leucine or isoleucine. The amount of carbon introduced into the MgB2 structure depends on the amino acid and is surprisingly higher for glycine, which has the lowest carbon content among the aliphatic amino acids. The critical temperatures of samples doped with all kinds of additives were lower than for the undoped sample. The critical current density was influenced by the additives to different extents, alanine, valine and leucine yielding the best results. The pinning force is also larger for these additives at T < 30 K. An analysis of the normalized flux pinning force behavior leads to the conclusion that point pinning is predominant in all samples.

Proper characterisation of investigated samples is vital when studying superconductivity as impurities and doping inhomogeneities can affect the physical properties of the measured system. We present a method where a polarised neutron imaging setup utilises the precession of spin-polarised neutrons in the presence of a trapped field in the superconducting sample to spatially map out the critical temperature for the phase transition between superconducting and non-superconducting states. We demonstrate this method on a superconducting crystal of the prototypical high-temperature superconductor (La,Sr)2CuO4. The results, which are backed up by complementary magnetic susceptibility measurements, show that the method is able to resolve minor variations in the transition temperature across the length of the LSCO crystal, caused by inhomogeneities in strontium doping.

ZnO films prepared on glass plates using a water based coating solution are characterized and tested for methylene blue dye photocatalytic decolourization in various types of waters (demineralized water, sea‐, and lake‐water). The influence of various parameters such as wavelength and attenuation of incident radiation by dye and/or organic matter is studied. In demineralized water, up to 90% decoloration is achieved within 1 h with 365 nm irradiation on a 10 ml solution. Although the ZnO films still show some activity when illuminated by standard visible light lamps, the efficiency of the photocatalytic process is greatly reduced. Natural waters result in a significant decrease of the photocatalytic activity, under both UV and visible light irradiation. The main factor is believed to be enhanced UV light absorption within the liquid. The influence of organic and mineral matter in natural waters is briefly discussed.

MgB2 bulk samples were made by means of reaction of elemental Mg and B powders with or without additions of methylene blue trihydrate, a carbon source, which melts at high temperature upon decomposition. The Tc of the MgB2 phase as well as its a-axis parameter were decreased as a result of carbon doping, whereas the c-axis parameter only shows a weak tendency for increasing. The critical current density of MgB2 was improved both in self-field and under applied magnetic field for T ≤ 25 K, the best results being obtained for 0.5–1.0 wt.% methylene blue trihydrate addition. Based on normalized flux pinning force (f(b)) versus reduced field (b) plots, it was found that the flux pinning mechanism at low reduced field is similar for all samples, with a behavior close to the predictions of the point pinning model. However, for b larger than 1, the behavior of f(b) is significantly altered in the methylene blue trihydrate added samples and tends towards the surface pinning model. Methylene blue trihydrate is an efficient carbon source and furthermore provides a liquid phase between 200 °C and 450 °C, which may have some influence on the critical current density improvements at low field.

We report the electrical, magnetic and magnetotransport properties of Na and Mo dual doped Ca3-2xNa2xCo4-xMoxO9 (0 ≤ x ≤ 0.15) polycrystalline samples. The results indicate that the strength of ferrimagnetic interaction decreases with increase in doping, as is evident from the observed decrease in Curie temperatures (TC). The substitution of non-magnetic Mo6+ ions (4d0) in CoO2 layers and the presence of oxygen vacancies are responsible for decrease in ligand field strength, which results in an enhanced magnetization in the low doped x = 0.025 sample due to a change from the low spin to partial high spin electron configuration. The electrical resistivity of samples exhibits a semiconducting-like behavior in the low temperature range, a strongly correlated Fermi liquid-like behavior in the intermediate temperature range, and an incoherent metal-like behavior in the temperature range 210-300 K. All the samples show a large negative magnetoresistance (MR) at low temperature with a maximum MR value of -59% for the x = 0.025 sample at 2 K and 16 T applied field. The MR values follow the observed trend in magnetization at 5 K and sharply increase below the Curie temperatures of the samples, suggesting that the ferrimagnetic interactions are mainly responsible for the decrease in electrical resistivity under an applied magnetic field.