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This article presents the method of size control of cobalt-doped zinc oxide nanoparticles (Zn1−xCoxO NPs) obtained by means of the microwave solvothermal synthesis. Zinc acetate dihydrate and cobalt(II) acetate tetrahydrate dissolved in ethylene glycol were used as the precursor. It has been proved by the example of Zn0.9Co0.1O NPs (x = 10 mol %) that by controlling the water quantity in the precursor it is possible to precisely control the size of the obtained Zn1−xCoxO NPs. The following properties of the obtained Zn0.9Co0.1O NPs were tested: skeleton density (helium pycnometry), specific surface area (BET), dopant content (ICP-OES), morphology (SEM), phase purity (XRD), lattice parameter (Rietveld method), average crystallite size (FW1/5/4/5M method and Scherrer’s formula), crystallite size distribution (FW1/5/4/5M method), and average particle size (from TEM and SSA). An increase in the water content in the precursor between 1.5% and 5% resulted in the increase in Zn0.9Co0.1O NPs size between 28 nm and 53 nm. The X-ray diffraction revealed the presence of only one hexagonal phase of ZnO in all samples. Scanning electron microscope images indicated an impact of the increase in water content in the precursor on the change of size and shape of the obtained Zn0.9Co0.1O NPs. The developed method of NPs size control in the microwave solvothermal synthesis was used for the first time for controlling the size of Zn1−xCoxO NPs.

The structural investigation of InGaN/GaN:Si multiple quantum well (MQW) samples grown by low-pressure metal-organic vapor phase epitaxy (LP-MOVPE) in a two temperatures (2T) process on high-pressure GaN mono-crystalline substrates is performed by transmission electron microscopy (TEM). A sample in which barriers and wells were grown at 780 °C is compared with another in which the barriers were deposited at 900 °C and the wells at 730 °C. For both samples the indium composition in the QWs reaches the level of about 20 at.%. The local indium composition was measured through strain measurements by digital processing from the lattice fringes images taken by TEM. Cross-sectional investigations are performed in two zone axes – [] and [] – with the use of axial and off-axis illumination. During TEM investigations the formation of “false indium clusters ” of the size of 2–4 nm was observed for both samples just after 2 min of LaB6 electron beam illumination at 200 kV. Large lateral fluctuations of indium content in the QWs of the length of 30–130 nm were detected in 2T sample. The plan view analysis was carried out to characterize the anisotropy of the indium fluctuation inside the QWs.

P>The structure of GaMnAs nanowires (NW) with nominal Mn concentration of up to 7 at% was investigated by transmission electron microscopy. The (Ga,Mn)As NW were grown on epiready GaAs(001) n-type wafers by molecular beam epitaxy. The crystal structure of the NW was determined to be zinc-blende. NW with Mn concentrations lower than 5 at% grow along the > direction. NW with higher Mn concentrations grow along the > direction and reveal a branching structure. The main nanowire and branches grow along the > directions belonging to only one {111} plane.

The stopping power values of 89 Y ions in carbon, nickel and gold were measured with accuracy to better than 5% in the energy range from 0.03 to 8.2 MeV/u. The newly developed B-TOF method was used for the measurements. The results are compared with theoretical and semi-empirical predictions. For this ion/absorber combination no prior experimental data are available.

A spectrometer that uses a set of silicon detectors and a combination of two magnetic fields for separation and for transportation of electrons from the target position to the silicon detectors has been constructed at the University of Lodz for “in-beam” studies of internal conversion electrons. The separation of electrons from positrons is achieved in a simplified mini-orange set-up. The transportation field is produced by a set of permanent magnets arranged in a form of coaxial rings. The background from delta electrons and gamma rays is highly reduced. The spectrometer was designed to be coupled to OSIRIS-II, the array of gamma-ray detectors at the Warsaw Heavy Ion Laboratory. The performance of the spectrometer is illustrated by examples of spectra obtained from the conversion electron spectrometer and also the OSIRIS-II array, which were recorded in- and off- beam.

Great Mosque of Damascus was built between 705 and 715 by the Umayyad Caliph al-Walid I. However, the origins of this building dates to the distant past. At first it was a location of an ancient Aramaean temple dedicated to the god Hadad. With Hellenization the temple was dedicated to Zeus and in the first century BC the Romans transformation it into the Temple of Jupiter Damascenus. In 391 Emperor Theodosius converted the temple into Christian Cathedral of Saint John. Erection of the mosque by Caliph al-Walid I was under strong influence of earlier constructions. Meaning and consequences of such transitions, from the Roman temple (there is almost no data of the Aramaic building) through the Christian Cathedral to the Islamic mosque is an interesting process. Issue not only within the art and architecture, but what is more, in a religious aspect of the continuity of sacred space.

This paper gives an overview of the development of an environmental-friendly small bipropellant rocket engine at the Institute of Aviation in Warsaw, Poland. 98% concentration hydrogen peroxide oxidizer and Jet-A fuel are used. A reliable pressure-fed system was chosen and system assembly tests are on-going. The final goal is to enable building and flight-qualifying a larger engine, possible to be used as a large satellite thruster and orbit transfer propulsion system. The paper covers the design and tests of a sub-scale, high contraction ratio, 250-Newton-thrust rocket engine. Fuel is injected into the oxidizer gaseous catalytic decomposition products and pseudo-hypergolic ignition occurs. Results of test firings are presented, with thrust, pressure and temperature measurements given. Special attention is drawn to the process of kerosene autoignition. A novel investigation of kerosene autoignition for very low O/F values, when a high contraction ratio is utilized, was made.

9 pags.; figs., © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Due to the development of novel manufacturing technologies and the increasing availability of nano-/micromaterials, plasmonics has become an emerging field in photonics research. Although the fabrication of metallic elements has already been widely demonstrated, the development of 3D plasmonic materials is progressing slowly. This paper reports the development of a self-organized, 3D nanoplasmonic eutectic composite that exhibits localized surface plasmon resonance at 595 nm. This eutectic composite is produced by directional solidification with the micro-pulling-down method and consists of a 3D, multiscale network of silver, nanometer-thick, micron-long sheets, and triangular cross-section microprecipitates embedded in a crystalline bismuth oxide matrix. Annealing at 600 °C further refined the structure and introduced metallic nanoparticles that exhibited plasmonic resonance in the optical region of the spectrum. This is the first demonstration of plasmonic behavior in a eutectic-based composite, which is engineered specifically for this purpose using a self-organization mechanism., he authors thank the Maestro Project (2011/02/A/ST5/00471) and the Preludium Project (2012/07/N/ST5/02428) from the National Science Centre, the Project operated within the Foundation for Polish Science Team Programme cofinanced by the EU European Regional Development Fund and the AFOSR Project 14RT0477: NOE Novel metamaterials and plasmonic materials properties enabled by the directional Eutectic solidification for support of this work.

Palladium nanograins placed in carbonaceous matrix shows many interesting properties connected to ability of hydrogen adsorption/absorption. Carbonaceous-palladium (C-Pd) films based on these materials change their structure and form, electrical conductivity, capacitance as well as optical absorption, transmission and reflection properties. These effects are connected to an incorporation of hydrogen atoms into palladium lattice [1], what change not only lattice constant [2] but also electric [3] and optical [4] properties of resulting material.

Structural, topographical and morphological changes of carbonaceous-palladium (C-Pd) films obtained by physical vapor deposition /chemical vapor deposition (PVD/CVD) method were studied. Effect of changes in these properties under the influence of CVD process temperature on the hydrogen sensitivity of these films is discussed. Scanning electron microscopy (SEM) observations were used to investigate the topography and morphology of an initial (PVD) film and the film modified in CVD process (PVD/CVD film) at different temperatures. The changes of film’s morphology after modification performed at various temperatures (500, 550, 600, 650, 700 and 750°C) caused changes in their resistance. The electrical measurements carried out in the presence of gas containing 1vol % of hydrogen showed different sensing characteristics for various films. The highest hydrogen sensitivity and the fastest response were observed for films modified at the temperature of 500°C and 550°C. In SEM images on surface of these films palladium nanograins with different sizes were observed. For films modified at the temperatures higher than 600°C Pd nanograins placed under superficial very thin carbonaceous layer were found.

An effective, simple and practically useful method to incorporate fluorescent nanoparticles inside live biological cells was developed. The internalization time and concentration dependence of a frequently used liposomal transfection factor (Lipofectamine 2000) was studied. A user friendly, one-step technique to obtain water and organic solvent soluble Er(3+) and Yb(3+) doped NaYF4 nanoparticles coated with polyvinylpyrrolidone was obtained. Structural analysis of the nanoparticles confirmed the formation of nanocrystals of the desired sizes and spectral properties. The internalization of NaYF4 nanoparticles in HeLa cervical cancer cells was determined at different nanoparticle concentrations and for incubation periods from 3 to 24 h. The images revealed a redistribution of nanoparticles inside the cell, which increases with incubation time and concentration levels, and depends on the presence of the transfection factor. The study identifies, for the first time, factors responsible for an effective endocytosis of the up-converting nanoparticles to HeLa cells. Thus, the method could be applied to investigate a wide range of future 'smart' theranostic agents. Nanoparticles incorporated into the liposomes appear to be very promising fluorescent probes for imaging real-time cellular dynamics.

A facile sol-gel synthesis of novel ZnO/MgO/Fe2O3 nanoparticles (NPs) is reported and their performance is compared to that of ZnO/MgO. Powder x-ray diffraction (XRD) patterns reveal the crystal structure of the prepared samples. The average particle size of the sample was found to be 4.8 nm. The optical properties were determined by UV-vis absorption and fluorescence measurements. The NPs are stable in biologically relevant solutions (phosphate buffered saline (PBS), 20 mM, pH = 7.0) contrary to ZnO/MgO NPs which degrade in the presence of inorganic phosphate. Superparamagnetic properties were determined with a superconducting quantum interference device (SQUID). Biocompatible and stable in PBS ZnO/MgO/Fe2O3 core/shell composite nanocrystals show luminescent and magnetic properties confined to a single NP at room temperature (19-24 ° C), which may render the material to be potentially useful for biomedical applications.

Near-band-edge excitonic emission shift is investigated as a measure of the local strain in GaN nanowires with single AlxGa1−xN sections of various Al contents (x = 0.0, 0.22, 0.49, 1.0). Complementary data obtained by spatially and spectrally resolved cathodoluminescence spectroscopy and imaging of individual nanowires at low temperature, high resolution X-ray diffraction, and transmission electron microscopy are used to determine the correspondence between the cathodoluminescence emission energy and the strain in the GaN core of the nanowire surrounded by the AlxGa1−xN shell formed during the growth of AlxGa1−xN sections by catalyst-free plasma-assisted molecular beam epitaxy. In majority of nanowires, the blue-shift of GaN cathodoluminescence follows the evolution expected for the GaN core under uniaxial compressive strain along the axis of the structure.

High-pressure and time-resolved studies of the optical emission from n-type doped GaN/AlN multi-quantum-wells (MQWs) with various well thicknesses are analysed in comparison with ab initio calculations of the electronic (band structure, density of states) and optical (emission energies and their pressure derivatives, oscillator strength) properties. The optical properties of GaN/AlN MQWs are strongly affected by quantum confinement and polarization-induced electric fields. Thus, the photoluminescence (PL) peak energy decreases by over 1 eV with quantum well (QW) thicknesses increasing from 1 to 6 nm. Furthermore, the respective PL decay times increased from about 1 ns up to 10 μs, due to the strong built-in electric field. It was also shown that the band gap pressure coefficients are significantly reduced in MQWs as compared to bulk AlN and GaN crystals. Such coefficients are strongly dependent on the geometric factors such as the thickness of the wells and barriers. The transition energies, their oscilla...

Molecular beam epitaxy growth and basic physical properties of quaternary AlInGaN layers, sufficiently thick for construction of electron blocking layers (EBL), embedded in ternary InGaN layers are presented. Transmission electron microscopy (TEM) measurement revealed good crystallographic structure and compositional uniformity of the quaternary layers contained in other nitride layers, which are typical for construction of nitride based devices. The AlInGaN layer was epitaxially compatible to InGaN matrix, strained, and no strain related dislocation creation was observed. The strain penetrated for limited depth, below 3 nm, even for relatively high content of indium (7%). For lower indium content (0.6%), the strain was below the detection limit by TEM strain analysis. The structures containing quaternary AlInGaN layers were studied by time dependent photoluminescence (PL) at different temperatures and excitation powers. It was shown that PL spectra contain three peaks: high energy donor bound exciton pea...

A microwave, solvothermal synthesis of hydroxyapatite (HAp) nanopowder with a programmed material resorption rate was developed. The aqueous reaction solution was heated by a microwave radiation field with high energy density. The measurements included powder X-ray diffraction (PXRD) and the density, specific surface area (SSA), and chemical composition as specified by the inductively coupled plasma optical emission spectrometry technique (ICP-OES). The morphology and structure were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A degradation test in accordance with norm ISO 10993-4 was conducted. The developed method enables control of the average grain size and chemical composition of the obtained HAp nanoparticles by regulating the microwave radiation time. As a consequence, it allows programming of the material degradation rate and makes possible an adjustment of the material activity in a human body to meet individual resorption rate needs. The authors synthesized a pure, fully crystalline hexagonal hydroxyapatite nanopowder with a specific surface area from 60 to almost 240 m2/g, a Ca/P molar ratio in the range of 1.57–1.67, and an average grain size from 6 nm to over 30 nm. A 28-day degradation test indicated that the material solubility ranged from 4 to 20 mg/dm3.

Magnetic N-benzyl-O-carboxymethylchitosan nanoparticles were synthesized through incorporation and in situ methods and characterized by Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, and magnetization measurements. Indomethacin was incorporated into the nanoparticles via the solvent evaporation method. The indomethacin-loaded magnetic nanoparticles were characterized by the same techniques, and also by transmission electron microscopy. The nanoparticles containing the polymer showed a drug loading efficiency of between 60.8% and 74.8%, and the magnetic properties were not significantly affected by incorporation of the drug. The in vitro drug release study was carried out in simulated body fluid, pH 7.4 at 37°C. The profiles showed an initial fast release, which became slower as time progressed. The percentage of drug released after 5 h was between 60% and 90%, and the best fitting mathematical model for drug release was the Korsmeyer-Peppas model, indicating a Fickian diffusion mechanism.

The decay of the \(\ensuremath I^{\pi}=K^{\pi}=8^{-}\) isomeric state at 2340keV in 132Ce has been investigated in the 120Sn(16O, 4n)132Ce reaction. The measurements were carried out in e -\( \gamma\) and \( \gamma\) -\( \gamma\) coincidence modes using an electron spectrometer coupled to the OSIRIS II gamma-ray array at the Heavy Ion Laboratory of the University of Warsaw. Experimentally obtained internal conversion coefficients for the \(\ensuremath 8^{-} \rightarrow 6^{+}\) and \(\ensuremath 8^{-} \rightarrow 5^{+}\) transitions allowed the multipolarities, mixing ratios, reduced transition probabilities and hindrance factors to be determined.

We present the nanocomposite carbonaceous-palladium (C-Pd) thin films prepared by physical vapor deposition (PVD) and chemical vapor deposition (CVD) methods. Scanning electron microscope (SEM) and transmission electron microscope (TEM) methods were used to study the topography, morphology and structure of carbon and palladium nanograins contained in these films. The quantitative analysis of the elemental composition of C-Pd films was determined by energy-dispersive spectroscopy (EDS). The initial PVD films were modified in a CVD quartz reactor using xylene (the mixture of isomers) as a modifying factor at different times (5, 10 and 30 minutes) at a constant temperature of 650°C in atmospheric pressure. It was observed that the average size of palladium nanograins increased with an increasing duration of modification process. The differences in microstructures observed in the CVD films modified at different times, affect their response in measurements of resistance changes in the gas containing H2 in various concentrations. All samples were measured by cathodoluminescence (CL) method. In CL studies a large amount of objects with high intensity of CL was found. Some of them show the emission bands both at 450 nm and 750 nm. Other reveals emission band only at 450 nm. CL observations show that Pd nanograins coated by graphite shells exhibit optical activity.

In the present work, we demonstrated a new method of graphene films transferring applying a marker-frame instead of polymer-like films as a support. This method is an alternative that is much faster, cheaper and freely available to all. Our technique guarantees cleaner graphene surface and no polymer residues on it. Consequently, it significantly increases the applicability of graphene. For instance, one can think of using graphene as a component of nanocomposites or coupling it with other nanomaterials. As an example we showed graphene films suspended on GaN nanowires. The characterization of the properties of graphene transferred following the enhanced frame method was performed by Raman spectroscopy, as well as by carrying out SEM imaging and conducting TEM investigations.

One-dimensional (1D) ZnO nanostructures have been widely studied because of their electronic and optoelectronic applications. This report discusses the morphology, optical, electrical and sensory properties of polycrystalline ZnO nanofibers (NFs). We observed that the electrospun ceramic NFs interband emission increases with the nanocrystal size, consistent with decreasing of the surface-to-volume ratio. The observation is novel for the electrospun ceramic NFs. The chemical composition and structural characterization reveal that the NFs consist of ZnO wurzite nanocrystals, whose mean diameters increase from 7 to 22 nm with calcination temperature. Emission properties are studied by cathodo- and photoluminescence. The NFs are applied to construct light, gas and liquid sensors. We find an increase of the NFs conductivity by three orders of magnitude under UV illumination as a result of desorption of molecular oxygen from the nanocrystal surface. We study the influence of oxygen on NF conductivity by purging the NFs with air or nitrogen. We show that the flow of nitrogen removes the oxygen resulting in an important increase of the conductivity. Also, we study the dynamics of this process with and without UV illumination. We show sensitivity of the NFs to liquid environment by studying the conductivity of NFs immersed in water and ethanol and find an increased conductivity with respect to a dry air environment. These light- and environmental-sensitive ZnO NFs have useful optical and electronic properties for building high-performance sensors.

Carbon–palladium composites have been investigated by the method of transmission electron microscopy. The composites have been obtained by two different processes: physical vapor deposition (PVD) and chemical vapor deposition (CVD). The relation between the average size of a palladium particle, the time, and temperature has been carried out. The samples were annealed at different temperatures—from $$500\,^{\circ }\hbox {C}$$ to $$750\,^{\circ }\hbox {C}$$ but also for three different times, that is, 5 min, 10 min, and 30 min. Activation energies were calculated from the Arrhenius equation. Obtained values for PVD and PVD/CVD samples are: $$64.6\,\hbox {kJ}{\cdot }\hbox {mol}^{-1}$$ and $$38.8\,\hbox {kJ}{\cdot }\hbox {mol}^{-1}$$ , respectively. Determination of the activation energy will be useful in controlling the growth of palladium grains. Significant differences in values for both series resulted from encapsulation in graphite–palladium particles, which were obtained in the PVD/CVD process. Those graphite planes are formed at temperatures above $$600\,\,^{\circ }\hbox {C}$$ and significantly slow down the growth of palladium particles.