Pediatric Mycoplasma Pneumonia: The Radiographic Patterns and Review of the Literature.

PURPOSE: The purpose of the present paper was to evaluate the clinical and chest radiographic features of pediatric patients with serologically proven Mycoplasma pneumoniae pneumonia. MATERIALS AND METHODS: The clinical records and chest radiographs of 55 consecutive patients (28 male, 27 female) with serologically positive IgG mycoplasma pneumonia were reviewed. The pneumonic infiltrates were described on chest radiography into 3 different patterns as a peribronchovascular infiltration, reticulonodular infiltration and consolidation. RESULTS: More than 91% of patients presented with cough and 70% of patients had fever. Chest radiographs displayed three different patterns: (i) peribronchovascular infiltration (n=33, 60%); (ii) reticulonodular infiltration (n=12, 22%); (iii) consolidation (n=10, 18%). Bilateral peribronchovascular infiltration in central and middle lung zones were frequently seen (n=33, 60%). Other radiological features were unilateral lesions in 51% of patients, pleural effusion in 18%, and hilar lymphadenopathy in 20%. CONCLUSION: There are various radiological features of mycoplasma pneumonia in children. Bilateral peribronchovascular infiltration confined to central and middle lung regions seems to be more closely associated with mycoplasma infection.

Efficient CuO/Ag2WO4 photoelectrodes for photoelectrochemical water splitting using solar visible radiation.

Water splitting energy production relies heavily on the development of high-performance photoelectrochemical cells (PECs). Among the most highly regarded semiconductor materials, cupric oxide (CuO) is an excellent photocathode material. Pristine CuO does not perform well as a photocathode due to its tendency to recombine electrons and holes rapidly. Photocathodes with high efficiency can be produced by developing CuO-based composite systems. The aim of our research is to develop an Ag2WO4/CuO composite by incorporating silver tungstate (Ag2WO4) nanoparticles onto hydrothermally grown CuO nanoleaves (NLs) by successive ionic layer adsorption and reaction (SILAR). To prepare CuO/Ag2WO4 composites, SILAR was used in conjunction with different Ag2WO4 nanoparticle deposition cycles. Physicochemical characterization reveals well-defined nanoleaves morphologies with tailored surface compositions. Composite CuO/Ag2WO4 crystal structures are governed by the monoclinic phase of CuO and the hexagonal phase of Ag2WO4. It has been demonstrated that the CuO/Ag2WO4 composite has outstanding performance in the PEC water splitting process when used with five cycles. In the CuO/Ag2WO4 photocathode, water splitting activity is observed at low overpotential and high photocurrent density, indicating that the reaction takes place at low energy barriers. Several factors contribute to PEC performance in composites. These factors include the high density of surface active sites, the high charge separation rate, the presence of favourable surface defects, and the synergy of CuO and Ag2WO4 photoreaction. By using SILAR, silver tungstate can be deposited onto semiconducting materials with strong visible absorption, enabling the development of energy-efficient photocathodes.

Plasmon-Enhanced Light Absorption in (p-i-n) Junction GaAs Nanowire Solar Cells: An FDTD Simulation Method Study.

A finite-difference time-domain method is developed for studying the plasmon enhancement of light absorption from vertically aligned GaAs nanowire arrays decorated with Au nanoparticles. Vertically aligned GaAs nanowires with a length of 1 µm, a diameter of 100 nm and a periodicity of 165-500 nm are functionalized with Au nanoparticles with a diameter between 30 and 60 nm decorated in the sidewall of the nanowires. The results show that the metal nanoparticles can improve the absorption efficiency through their plasmonic resonances, most significantly within the near-bandgap edge of GaAs. By optimizing the nanoparticle parameters, an absorption enhancement of almost 35% at 800 nm wavelength is achieved. The latter increases the chance of generating more electron-hole pairs, which leads to an increase in the overall efficiency of the solar cell. The proposed structure emerges as a promising material combination for high-efficiency solar cells.

Light-induced high-spin state in ZnO nanoparticles.

The effects of white-light irradiation on ∼15 nm diameter ZnO nanoparticles are investigated by means of electron paramagnetic resonance, near liquid-nitrogen and liquid-helium temperatures. Under dark conditions, usual core- and surface-defects are detected, respectively, at g = 1.960 and g = 2.003. Under white-light illumination, the core-defect signal intensity is strongly increased, which is to be correlated to the light-induced conductivity's augmentation. Beside, a four-lines structure appears, with the same gravity center as that of the surface defects. Simulations and intensity power-dependence measurements show that this four-line-structure is very likely to arise from a localized high spin S = 2, induced by light irradiation, and subjected to a weak axial anisotropy. At 85 K, this high-spin state can last several hours after the light-irradiation removal, probably due to highly spin-forbidden recombination process. The possible excited resonant complexes at the origin of this signal are discussed. Other light-induced S = 1/2-like centers are detected as well, which depend on the nanoparticles growth conditions.

Core-defect reduction in ZnO nanorods by cobalt incorporation.

Zinc oxide (ZnO) nanorods grown by the low-temperature (90 °C) aqueous chemical method with different cobalt concentration within the synthesis solution (from 0% to 15%), are studied by electron paramagnetic resonance (EPR), just above the liquid helium temperature. The anisotropic spectra of substitutional Co2+ reveal a high crystalline quality and orientation of the NRs, as well as the probable presence of a secondary disordered phase of ZnO:Co. The analysis of the EPR spectra indicates that the disappearance of the paramagnetic native core-defect (CD) at [Formula: see text] is correlated with the apparition of the Co2+ ions lines, suggesting a gradual neutralization of the former by the latter. We show that only a little amount of cobalt in the synthesis solution (about 0.2%) is necessary to suppress almost all these paramagnetic CDs. This gives insight in the experimentally observed improvement of the crystal quality of diluted ZnO:Co nanorods, as well as into the control of paramagnetic defects in ZnO nanostructures.

EPR investigation of pure and Co-doped ZnO oriented nanocrystals.

Pure and cobalt-doped zinc oxide aligned nanorods have been grown by the low-temperature (90 °C) aqueous chemical method on amorphous ZnO seed layer, deposited on a sapphire substrate. High crystallinity of these objects is demonstrated by the electron paramagnetic resonance investigation at liquid helium temperature. The successful incorporation of Co2+ ions in substitution of Zn2+ ones in the ZnO matrix has also been confirmed. A drastic reduction of intrinsic ZnO nanorods core defects is observed in the Co-doped samples, which enhances the structural quality of the NRs. The quantification of substitutional Co2+ ions in the ZnO matrix is achieved by comparison with a reference sample. The findings in this study indicate the potential of using the low-temperature aqueous chemical approach for synthesizing material for spintronics applications.

Low-Frequency Self-Powered Footstep Sensor Based on ZnO Nanowires on Paper Substrate.

In this work, we design and fabricate a wireless system with the main operating device based on zinc oxide (ZnO) nanowires. The main operating device is based on piezoelectric nanogenerator (NG) achieved using ZnO nanowires grown hydrothermally on paper substrate. The fabricated NG is capable of harvesting ambient mechanical energy from various kinds of human motion, e.g., footsteps. The harvested electric output has been used to serve as a self-powered pressure sensor. Without any storage device, the signal from a single footstep has successfully triggered a wireless sensor node circuit. This study demonstrates the feasibility of using ZnO nanowire piezoelectric NG as a low-frequency self-powered sensor, with potential applications in wireless sensor networks.

A flexible anisotropic self-powered piezoelectric direction sensor based on double sided ZnO nanowires configuration.

We have successfully synthesized highly dense and well aligned zinc oxide nanowires (NWs) on the two sides of a PEDOT: PSS substrate by a single step low temperature hydrothermal method. The grown sample was used to fabricate a double sided piezoelectric nanogenerator (NG). The maximum harvested output power density from the fabricated double sided NG configuration was about 4.44 mW cm(-2). The results obtained from the present double sided NG were approximately double the output from a single side. In addition to that, the voltage polarity of the harvested voltage from the two sides of the NG has been investigated. The results showed that upon bending, an anisotropic voltage polarity is generated on the two sides. Indicating that, this double sided NG can be used as a self-powered voltage polarity based direction sensor. The results of the present flexible double sided NG is very promising for harvesting energy from irregular mechanical energy sources in the surrounding environment. In addition, the fabricated configuration showed stability for sensing and can be used in surveillance and security applications.

A selective potentiometric copper (II) ion sensor based on the functionalized ZnO nanorods.

In this work, ZnO nanorods were hydrothermally grown on the gold-coated glass substrate and characterized by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) techniques. The ZnO nanorods were functionalized by two different approaches and performance of the sensor electrode was monitored. Fourier transform infrared spectroscopy (FTIR) was carried out for the confirmation of interaction between the ionophore molecules and ZnO nanorods. In addition to this, the surface of the electrode was characterized by X-ray photoelectron spectroscopy (XPS) showing the chemical and electronic state of the ionophore and ZnO nanorod components. The ionophore solution was prepared in the stabilizer, poly vinyl chloride (PVC) and additives, and then functionalized on the ZnO nanorods that have shown the Nernstian response with the slope of 31 mV/decade. However, the Cu2+ ion sensor was fabricated only by immobilizing the selective copper ion ionophore membrane without the use of PVC, plasticizers, additives and stabilizers and the sensor electrode showed a linear potentiometric response with a slope of 56.4 mV/decade within a large dynamic concentration range (from 1.0 x 10(-6) to 1.0 x 10(-1) M) of copper (II) nitrate solutions. The sensor showed excellent repeatability and reproducibility with response time of less than 10 s. The negligible response to potentially interfering metal ions such as calcium (Ca2+), magnesium (Mg2+), potassium (K+), iron (Fe3+), zinc (Zn2+), and sodium (Na+) allows this sensor to be used in biological studies. It may also be used as an indicator electrode in the potentiometric titration.

Single nanowire-based UV photodetectors for fast switching.

Relatively long (30 µm) high quality ZnO nanowires (NWs) were grown by the vapor-liquid-solid (VLS) technique. Schottky diodes of single NW were fabricated by putting single ZnO NW across Au and Pt electrodes. A device with ohmic contacts at both the sides was also fabricated for comparison. The current-voltage (I-V) measurements for the Schottky diode show clear rectifying behavior and no reverse breakdown was seen down to -5 V. High current was observed in the forward bias and the device was found to be stable up to 12 V applied bias. The Schottky barrier device shows more sensitivity, lower dark current, and much faster switching under pulsed UV illumination. Desorption and re-adsorption of much smaller number of oxygen ions at the Schottky junction effectively alters the barrier height resulting in a faster response even for very long NWs. The NW was treated with oxygen plasma to improve the switching. The photodetector shows high stability, reversibility, and sensitivity to UV light. The results imply that single ZnO NW Schottky diode is a promising candidate for fabricating UV photodetectors.

Intracellular ZnO Nanorods Conjugated with Protoporphyrin for Local Mediated Photochemistry and Efficient Treatment of Single Cancer Cell.

ZnO nanorods (NRs) with high surface area to volume ratio and biocompatibility is used as an efficient photosensitizer carrier system and at the same time providing intrinsic white light needed to achieve cancer cell necrosis. In this letter, ZnO nanorods used for the treatment of breast cancer cell (T47D) are presented. To adjust the sample for intracellular experiments, we have grown the ZnO nanorods on the tip of borosilicate glass capillaries (0.5 µm diameter) by aqueous chemical growth technique. The grown ZnO nanorods were conjugated using protoporphyrin dimethyl ester (PPDME), which absorbs the light emitted by the ZnO nanorods. Mechanism of cytotoxicity appears to involve the generation of singlet oxygen inside the cell. The novel findings of cell-localized toxicity indicate a potential application of PPDME-conjugated ZnO NRs in the necrosis of breast cancer cell within few minutes.

Stable White Light Electroluminescence from Highly Flexible Polymer/ZnO Nanorods Hybrid Heterojunction Grown at 50 degrees C.

Stable intrinsic white light-emitting diodes were fabricated from c-axially oriented ZnO nanorods (NRs) grown at 50 degrees C via the chemical bath deposition on top of a multi-layered poly(9,9-dioctylfluorene-co-N-(4-butylpheneylamine)diphenylamine)/poly(9,9dioctyl-fluorene) deposited on PEDOT:PSS on highly flexible plastic substrate. The low growth temperature enables the use of a variety of flexible plastic substrates. The fabricated flexible white light-emitting diode (FWLED) demonstrated good electrical properties and a single broad white emission peak extending from 420 nm and up to 800 nm combining the blue light emission of the polyflourene (PFO) polymer layer with the deep level emission (DLEs) of ZnO NRs. The influence of the temperature variations on the FWLED white emissions characteristics was studied and the devices exhibited high operation stability. Our results are promising for the development of white lighting sources using existing lighting glass bulbs, tubes, and armature technologies.

White Electroluminescence Using ZnO Nanotubes/GaN Heterostructure Light-Emitting Diode.

We report the fabrication of heterostructure white light-emitting diode (LED) comprised of n-ZnO nanotubes (NTs) aqueous chemically synthesized on p-GaN substrate. Room temperature electroluminescence (EL) of the LED demonstrates strong broadband white emission spectrum consisting of predominating peak centred at 560 nm and relatively weak violet-blue emission peak at 450 nm under forward bias. The broadband EL emission covering the whole visible spectrum has been attributed to the large surface area and high surface states of ZnO NTs produced during the etching process. In addition, comparison of the EL emission colour quality shows that ZnO nanotubes have much better quality than that of the ZnO nanorods. The colour-rendering index of the white light obtained from the nanotubes was 87, while the nanorods-based LED emit yellowish colour.

Zinc oxide nanorod based photonic devices: recent progress in growth, light emitting diodes and lasers.

Zinc oxide (ZnO), with its excellent luminescent properties and the ease of growth of its nanostructures, holds promise for the development of photonic devices. The recent advances in growth of ZnO nanorods are discussed. Results from both low temperature and high temperature growth approaches are presented. The techniques which are presented include metal-organic chemical vapour deposition (MOCVD), vapour phase epitaxy (VPE), pulse laser deposition (PLD), vapour-liquid-solid (VLS), aqueous chemical growth (ACG) and finally the electrodeposition technique as an example of a selective growth approach. Results from structural as well as optical properties of a variety of ZnO nanorods are shown and analysed using different techniques, including high resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM), photoluminescence (PL) and cathodoluminescence (CL), for both room temperature and for low temperature performance. These results indicate that the grown ZnO nanorods possess reproducible and interesting optical properties. Results on obtaining p-type doping in ZnO micro- and nanorods are also demonstrated using PLD. Three independent indications were found for p-type conducting, phosphorus-doped ZnO nanorods: first, acceptor-related CL peaks, second, opposite transfer characteristics of back-gate field effect transistors using undoped and phosphorus doped wire channels, and finally, rectifying I-V characteristics of ZnO:P nanowire/ZnO:Ga p-n junctions. Then light emitting diodes (LEDs) based on n-ZnO nanorods combined with different technologies (hybrid technologies) are suggested and the recent electrical, as well as electro-optical, characteristics of these LEDs are shown and discussed. The hybrid LEDs reviewed and discussed here are mainly presented for two groups: those based on n-ZnO nanorods and p-type crystalline substrates, and those based on n-ZnO nanorods and p-type amorphous substrates. Promising electroluminescence characteristics aimed at the development of white LEDs are demonstrated. Although some of the presented LEDs show visible emission for applied biases in excess of 10 V, optimized structures are expected to provide the same emission at much lower voltage. Finally, lasing from ZnO nanorods is briefly reviewed. An example of a recent whispering gallery mode (WGM) lasing from ZnO is demonstrated as a way to enhance the stimulated emission from small size structures.

Trapping and detection of single molecules in water.

An innovative nanoprobe-based device that can measure and adjust the pH, can mimic biochemistry, can create microscale vortices in water, and can be used to trap single molecules is presented. Because the analytes in question to trap and detect are small in dimensions, we start by presenting scaling issues and challenging limitations for miniaturized chemical nanosensors. Advantages of using nanoprobes e.g., isolated nanowires, as the components in chemical sensing are discussed. How the observation of the physical property can beneficially change with isomorphic scaling is highlighted. Some of the technology-related constrains are presented for specific sensors. Solutions to overcome such problems are also given. Different aspects, e.g., sample size and sensitivity, for chemical sensing at the nanoscale are highlighted.

The effect of the interlayer design on the electroluminescence and electrical properties of n-ZnO nanorod/p-type blended polymer hybrid light emitting diodes.

Hybrid light emitting diodes (LEDs) based on n-ZnO nanorods and blended polymers were fabricated and characterized. The blended polymers consisted of a blue emitting polymer and a charge transport polymer. The effect of the interlayer design on the electrical and electroluminescent characteristics of these hybrid LEDs was investigated. We demonstrated that by adding a calcium (2) acetylacetonate [Ca(acac)(2)] layer between the blended polymer layer and the ZnO nanorods, an increase in device performance was observed. The purpose of the extra layer was to act as a band offset stepping layer (offset divider). Moreover, the effect of the stepper layer thickness for this offset stepping layer was studied. The results indicate that LED performance is greatly affected by the presence and thickness of this band offset stepping layer.

Selective calcium ion detection with functionalized ZnO nanorods-extended gate MOSFET.

Zinc oxide nanorod-extended gate field effect transistor (MOSFET) is demonstrated for the detection of calcium (Ca(2+)) ions. ZnO nanorods were grown on the surface of a silver wire to produce an electrochemical nanosensor for selectively detecting Ca(2+). The electrochemical response from the interaction between the ZnO nanorods and Ca(2+) in an aqueous solution is coupled directly to the gate of a field effect transistor (MOSFET). The induced voltage change on the gate results in a measureable current response. In order to adapt the sensors for Ca(2+) ions measurements in biological fluids with sufficient selectivity and stability, a plastic membrane coating containing ionophores was applied on the nanorods. The sensor exhibited a linear response within the range of interest from 1 microM to 1 mM. This work demonstrates a simple technique for sensitive detection of Ca(2+) ions by efficient transfer of the chemical response directly to a standard electronic component producing a low impedance signal.

Buckling and mechanical instability of ZnO nanorods grown on different substrates under uniaxial compression.

Mechanical instability and buckling characterization of vertically aligned single-crystal ZnO nanorods grown on different substrates including Si, SiC and sapphire (α-Al(2)O(3)) was done quantitatively by the nanoindentation technique. The nanorods were grown on these substrates by the vapor-liquid-solid (VLS) method. The critical load for the ZnO nanorods grown on the Si, SiC and Al(2)O(3) substrates was found to be 188, 205 and 130 µN, respectively. These observed critical loads were for nanorods with 280 nm diameters and 900 nm length using Si as a substrate, while the corresponding values were 330 nm, 3300 nm, and 780 nm, 3000 nm in the case of SiC and Al(2)O(3) substrates, respectively. The corresponding buckling energies calculated from the force displacement curves were 8.46 × 10(-12), 1.158 × 10(-11) and 1.092 × 10(-11) J, respectively. Based on the Euler model for long nanorods and the J B Johnson model (which is an extension of the Euler model) for intermediate nanorods, the modulus of elasticity of a single rod was calculated for each sample. Finally, the critical buckling stress and strain were also calculated for all samples. We found that the buckling characteristic is strongly dependent on the quality, lattice mismatch and adhesion of the nanorods with the substrate.

Electrical characteristics and stability of gold and palladium Schottky contacts on ZnO nanorods.

The electrical characteristics and stability of Pd and Au Schottky contacts on ZnO nanorods grown on glass substrate have been investigated. The nanorods were grown using the aqueous chemical growth method. The nanorods were characterized with scanning electron microscopy (SEM), x-ray diffraction (XRD) and photoluminescence (PL). Prior to the metal contact deposition, an insulating PMMA layer was deposited between the nanorods. The best-produced Schottky contact was an as-deposited Pd/ZnO contact with an ideality factor of 1.74 ± 0.43 and a barrier height of 0.67 ± 0.09 eV. The relatively high ideality factor indicates that the current transport cannot be described by pure thermionic transport. The presence of surface states due to the high evaporation pressure is probably the reason for the high ideality factor. Post metal deposition annealing at 150 °C for 30 min in air lowered the barrier height and decreased the Au/ZnO ideality factor but increased it for Pd/ZnO. The current follows ohmic behavior when the applied forward bias, V(forward), is lower than 0.1 V, whereas for V(forward) between 0.1 and 0.45 V the current follows I∼exp(cV), and at higher forward biases the current-voltage characteristics follow the relation I∼V(2), indicating that the space-charge current-limiting mechanism is dominating the current transport.

Daily and seasonal activities of some sandflies from Surrugia village, Khartoum, Sudan.

The present study is concerned with four species of phlebotomine sandflies prevailing in Khartoum area between the years 1984 and 1987. Flies studied were Phlebotomus papatasi, Sergentomyia antennata, S. clydei and S. schewtzi. The indoor and outdoor daily rhythmic and biting activities were determined during the transmission season for both males and females P. papatasi. Peaks of daily activities and the time at which man is at greatest risk were determined. For each year the monthly relative population densities, populations structure and seasonal changes of sandflies were studied, in comparison with the pooled data of the four years. Seasonal density changes were correlated with temperature, relative humidity and rainfall prevailing in the area.