Surfaces that exhibit reversible wettability toward water are extremely important for a variety of technological applications. In this context, the development of superhydrophobic and superhydrophilic surfaces for self-cleaning applications has been receiving a great deal of attention in the last few years. In this review, an overview of the current state-of-science and technology of self-cleaning surfaces is presented. The current understanding of physics of wetting leading to surfaces with predictive, controllable and reversible wettability is first presented. The review then focuses on materials, mainly metal oxides and their composites, employed for self-cleaning applications. It is shown that, although conventionally oxides and polymers are considered for self-cleaning applications, recent developments point toward the use of artificially engineered surfaces with hierarchical roughness. Applications of self-cleaning films in non-conventional areas such as protection of fabrics, solar cells and structures related to cultural heritage are discussed. The review ends with an outlook for the future in terms of science and technology of self-cleaning surfaces.

Linear, ring and 3D structures of (ZnTe)n clusters for n = 2–6 are completely optimized using B3LYP/LanL2DZ basis set. The stability, dipole moment and point group for linear, ring and 3D structures are studied. The stability of the clusters is found to increase with the increase in the cluster size. The dipole moment of the cluster depends upon the asymmetry of the atoms in the structure. The HOMO-LUMO gap, electron affinity, ionization potential and stability factor of different isomers for these different structures are also compared and studied. From the observed studies it is found that the electronic and chemical properties are influenced by the electron affinity and HOMO-LUMO gap. The calculated parameters and the results of different structures will provide clear information to fabricate a new material that has commercial importance in the thin film solar cells and optoelectronic devices.

We present a novel multilayered architecture for memristive devices which provides an alternative to conventional conductive filament switching. In conventional resistive switching, conductive filaments form and extend stochastically under applied electrical bias, with longer filaments being subjected to magnified electric fields that amplify their growth rate, producing a spatially localized and highly non-uniform conduction front of filaments. This produces devices with large variations in resistive and capacitive properties that are difficult to tune. Here, we simulate a multilayered device structure with alternating ionic mobility that predicts the development of a quasi-uniform conduction front which amplifies memcapacitive properties of the device and reduces device-to-device variability. Furthermore, this novel structure is predicted to enable fine-tuned control of switching events, an important property for analog (multibit) memory and neuromorphic computing applications.

For the first time, thin-film CIGS solar cells have been fabricated by co-evaporation on specially developed non-conducting perlite (an aluminum potassium sodium silicate natural mineral of volcanic origin) glass-ceramic substrates to develop a fully integrated photovoltaic and building element. Such glass-ceramic material can meet the physical requirements to solar cells substrates as well as the cost goals. The preliminary data presented show that CIGS solar cells deposited on ceramic substrates can exhibit efficiency higher than 10%.

In this paper the set of photoelectromagnetic methods for determination of recombination and diffusion parameters of charge carriers in p-type mercury cadmium telluride epitaxial thin films at temperature range 77–125 K is offered. The set of methods includes the photoconductivity in magnetic field for Faraday and Voigt geometries, the photoelectromagnetic effect, the Hall effect and the measurements of magnetoconductivity. Such films parameters as concentrations and mobilities of heavy and light holes, mobility of minor electrons, electrons lifetime and ratio between holes and electrons lifetimes, surface recombination velocities can be determined with help of offered set.

Samples from sheets of the polymeric material polyester have been exposed to X-rays from a 50 kV X-ray tube in the dose range 10–100 kGy. The resultant effect of X-rays has been investigated using different techniques such as X-ray diffraction XRD, thermogravimetric analysis TGA, differential thermal analysis DTA and stress-strain measurements. The results indicate that the polyester decomposes in one weight loss stage. Also, the X-ray irradiation in the dose range 30–100 kGy led to a more compact structure of polyester, which resulted in an improvement in its thermal stability. The variation of transition temperatures with the X-ray dose has been determined using DTA. The polyester thermograms were characterized by the appearance of an endothermic peak due to the melting of the crystalline phase. The melting temperature of the polymer Tm was investigated to probe the crystalline domains of the polymer. At the dose range 30–100 kGy, the defect generated destroys the crystalline structure, thus reducing the melting temperature. In addition, the stress-strain measurements indicate that the X-ray irradiation at the same dose range 30–100 kGy yields crosslinked polyester of high resilience that is suitable for manufacturing protective clothes that reduce heat stress.

We used the electrospray deposition (ESD) method to fabricate organic photovoltaic devices with poly (3-hexyl-thiophene) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) blends of different composition ratios and different organic solvent solution, namely chloroform (CLF) and dichlorobenzene (DCB). The morphology and crystallinity of the active layers were investigated by means of atomic force microscopy (AFM), two-dimensional X-ray diffraction (XRD2) and optical absorption, spreading light on the peculiarities of the present growth technique, involving much faster solvent evaporation and film forming processes, and comparatively much more ordered strutures with less need of thermal annealing processes. The power conversion efficiency (PCE) under AM 1.5G solar simulation obtained for devices deposited from DCB as compared to those deposited from CLF, showed significant improvement, in fair agreement with what was found by the overall characterization of the physical properties.

Surface modification was performed on the indium-tin-oxide (ITO) thin films by oxygen inductive coupling plasma (O-ICP) and oxygen plasma immersion ion implantation (O-PIII). The electronic states of ITO surfaces were characterized by X-ray photoelectron spectroscopy (XPS). The observed peak shifts of O 1s, In 3d5/2 and Sn d5/2 core levels showed that the work function of ITO can be further enhanced by O-PIII treatment, compared with that of untreated and O-ICP treated surfaces. The deconvolution of O 1s spectrum and calculation of stoichiometry showed that the work function improvement should be attributed to the increase of effective oxygen content, namely, the elimination of oxygen vacancies. In addition, the measurement of Kelvin probe confirmed that an increment of the ITO work function by 1.1 eV was obtained on O-PIII treated sample and the results sustained our proposal.

CuInS2 thin films have been successfully prepared on Pyrex substrates using spray pyrolysis technique. In this work, we study the effect of the flow rate on the physical properties of CuInS2 thin films. X-ray diffraction pattern reveals the presence of tetragonal structure with (1 1 2) preferential orientation for CIS thin layers. Optical analysis by means of transmission T(λ) and reflection R(λ) measurements allows to determine the direct band gap energy value in the order of 1.44 eV, indicating that CuInS2 compound has absorbing properties favorable for applications in solar cell devices. Photoluminescence measurements are performed on CuInS2 crystals and the analysis reveals that the emission is mainly due to donor-acceptor pair transitions.

Si-rich oxide/SiO2 multilayer films with different N2O flow rates have been deposited by plasma enhanced chemical vapor deposition technique, and Si quantum dot (Si-QD)/SiO2 multilayer films are obtained by 1100 °C annealing. Steady photoluminescence (PL) spectra show that the main optical emission mechanism changes from quantum confinement effect of Si-QDs to interface defect states with increasing the flow rate of N2O. Curve fittings of time-resolved PL spectra show that two log-normal decay time distribution bands are obtained, and both the most frequent life-times decrease with increasing the flow rate of N2O, while increase with the red shift of detecting wavelength. Analyses indicate that defect states density and size distribution of Si-QDs strongly influence the PL decay properties.

Aerogel nanoparticles prepared with various Al concentrations were used as a target for the deposition of (V,Al) co-doped ZnO films by rf-magnetron sputtering on glass substrates. The influence of Al content on the structural and the optical properties of the Zn(V,Al)O films was investigated by X-ray diffraction and spectroscopic ellipsometry (SE). It is found that all films exhibit one high intensity (0 0 2) peak, indicating that they have c-axis preferred orientation due to self-texturing mechanism. SE measurements, used to determine the complex pseudo dielectric functions, were carried out at room temperature in the 1–6 eV photon energy region. The excitonic edge of the fundamental band gap (E0) transition in the imaginary part of the dielectric function of the Zn(V,Al)O films is observed around 3.5 eV and shows a dependence on the Al content. The E0 absorption edge of the Zn0.9−x V0.1AlxO alloys shows a blueshift from that of pure ZnO, reaching 389 meV for x = 0.02. This blueshift is interpreted by the Burstein-Moss effect. By analyzing the dielectric function, reduced effective mass m* of the Zn0.9−x V0.1AlxO alloy is extracted and shows good agreement with literature values.

We report on the fabrication and optoelectronic features of Tb3+ doped gadolinium oxide (Gd2O3) nanpowders. The nanosystems were found to exhibit cubic crystalline structure with an average crystallite size in the range of 11–24 nm. Inclusion of Tb3+ into Gd2O3 host has led to suppression of the optical gap but resulted in the enhanced refractive index of the corresponding nanophosphor. In the PL spectra, apart from the oxygen defect related emissions, Tb3+ mediated (0.5% of doping level) improved radiative emissions owing to 5D4→7F6 and 5D4→7F5 transitions were found to be located at ∼492 and ∼548 nm; respectively. Rare earth ion doped rare earth oxide nanopowders may find immediate scope in smart optoelectronic elements and advanced nanometric phosphors.

The structural, electronic and magnetic properties of transition metal TM (TM = Fe and Co) monatomic nanochains encapsulated inside and between (6,6) boron nitride nanotube (BNNT) bundle have been investigated by the first-principles calculations in the framework of the density functional theory. Our results show that intercalation of TM chains leads to the significant changes in the geometrical structure. All TM chains TM-Chs@BNNT bundle systems have negative formation energy so they are stable and exothermic. It is found that all these TM-Chs@BNNTs bundle systems are ferromagnetic and a spin splitting between spin up and down is observed. The spin polarization and the magnetic moment of the systems depend on the position and the type of the transition metal atomic chains.

We show that for identical changes in magnetic field, the temperature dependence of the change in isothermal entropy across the martensite-austenite phase transition in different Ni-Mn-In based off-stoichiometric Heusler alloys scales to a single curve. The temperature dependence of magnetoresistance across the same martensite-austenite phase transition in these alloys also scales to follow a similar curve. The temperatures corresponding to the peak value of the isothermal entropy change and the peak magnetoresistance for a particular applied magnetic field are correlated with distinct features observed in the magnetization vs. temperature and resistivity vs. temperature curves respectively of these alloys (in the same magnetic field). These findings can be utilized in estimating the useful temperature regime for the isothermal entropy change and magnetoresistance of Ni-Mn-In based alloys with newer compositions, and to predict the magnitude of these functionalities, without performing actual experiments.

Extensive use of minerals in the world entails the evaluation of major, minor and trace element contents in rocks of different areas. Instrumental neutron activation analysis and calibration free laser induced breakdown spectroscopy were successfully employed to identify and determine the concentration of elements in the rock samples which are collected from the untouched tropical forest area of Ethiopia. Using both techniques 26 minerals are identified and the concentration of each element was estimated and compared to one another. Due to the weak neutron source and the technique limitation, only eight elements of the rock samples were identified by neutron activation analysis. This study provides the baseline value of certain essential minerals in the rocks of studied area and the result shows that the studied area has great potential for mining of Pt and Zn elements. The performances of two analytical methods have been compared. Concentration analysis was done using a Calibration Free-laser induced breakdown spectroscopy algorithm in MATLAB environment.

Inductively coupled Ar-N2 plasma is characterized by Langmuir probe and optical emission spectroscopy (OES). The plasma parameters including electron temperature, electron number density and electron energy probability functions (EEPFs) are determined by the Langmuir probe for different discharge parameters such as rf power (10–100 W), filling pressure (0.02–0.4 mbar) and argon content (5–95%) in nitrogen discharge. Spectroscopic measurements enable the evaluation of active species concentration ([N],[N2]) in ground electronic state and dissociation fraction. Concentration of active species is increased with the increase in filling pressure in nitrogen discharge keeping argon as an actinometer. It is noticed that the actinometry is an efficient and reliable technique to calculate the concentration of ground electronic state of nitrogen species. Moreover, for different plasma conditions, the molecular dissociation fraction is enhanced, as the Ar content is increased from 5% to 95% in nitrogen discharge. It is found that that dissociation fraction strongly depends on filling pressure and Ar content in nitrogen discharge. Maximum dissociation is observed for 95% Ar at filling pressure of 0.06 mbar. It is also found that the plasma parameters and active species concentration significantly depend on discharge parameters and may be optimized by appropriate selection of discharge conditions.

In this article, a MEMS-based elastic fluidic actuator is presented. The actuator is driven at its natural frequency. The actuator consists of a thin film of two-phase fluid squeezed between two thin membranes with the top membrane attached to an actuation arm. The top membrane represents the elastic component which deforms under applied pressure. The results show that generated force and displacement amplitude of actuation arm are enhanced for resonant operation. Natural frequency of the actuator is tuned through selection of different actuator components. For current actuator design, maximum generated force and displacement amplitude obtained are approximately 39 mN/W and 16 μm/W, respectively. Natural frequency of the actuator ranges between 110 Hz and over 1000 Hz. This resonant-type actuator is suitable for applications where large generated forces and displacements are needed, such as pumping fluid through micro channels, and providing translational and rotational motion needed in microfluidics systems.

A joint diagnostic system was established for the diagnosis of laser-driven shock wave experiments. The system has high temporal resolution (time resolution ~12 ps) and high spatial resolution (spatial resolution ~7 μm) and fits for diagnostics of the experiment with small sample size and short time physical process. The joint diagnostic system was applied for shock wave measurement on the Shenguang-II laser facility. The passive shock breakout signal and active diagnostic signal were simultaneously obtained. The temporal measurement reliability of the system was verified using a multi-layered target. The experimental results show that the two measurement results were consistent.

The tight focusing of femtosecond radially polarized vortex laser pulse by a high numerical aperture objective is investigated in this paper. Based on Richards-Wolf vectorial diffraction theory, the electric field and the group velocity of the radially polarized vortex femtosecond laser pulse are studied in great detail. It finds that the femtosecond radially polarized vortex laser pulse can travel at various group velocities near the focus, that is, slower or faster than light velocity in vacuum, depending on the numerical aperture of the focusing objective system. Moreover, the effect of spherical aberration of objective, topological charge and time duration of the radially polarized vortex laser pulse on the group velocity distribution near the focus is discussed.

In this paper, we present the molecular density distribution measurement in turbulent nitrogen jet (Re ≈ 3×103), using acetone as molecular tracer. The tracer was seeded in the nitrogen jet by purging through the liquid acetone at ambient temperature. Planar laser sheet of 266 nm wavelength from frequency quadrupled, Q-switched, Nd:YAG laser was used as an excitation source. Emitted fluorescence images of jet flow field were recorded on CMOS camera. The dependence of planar laser induced fluorescence (PLIF) intensity on acetone vapor density was used to convert PLIF image of nitrogen jet into the density image on pixel-by-pixel basis. Instantaneous quantitative density image of nitrogen jet, seeded with acetone, was obtained. The arrowhead-shaped coherent turbulent structures were observed in the present work. It was found that coherent structures were non-overlapping with separate boundaries. Breaking of coherent structures into turbulence was clearly observed above four times jet width.