Violet-blue LEDs based on p-GaN/n-ZnO nanorods and their stability.

In this paper, we report a fabrication, characterization and stability study of p-GaN/n-ZnO nanorod heterojunction light-emitting devices (LEDs). The LEDs were assembled from arrays of n-ZnO vertical nanorods epitaxially grown on p-GaN. LEDs showed bright electroluminescence in blue (440 nm), although weaker violet (372 nm) and green-yellow (550 nm) spectral components were also observed. The device characteristics are generally stable and reproducible. The LEDs have a low turn-on voltage (∼5 V). The electroluminescence (EL) is intense enough to be noticed by the naked eye, at an injection current as low as ∼ 40 µA (2.1 × 10(-2) A cm(-2) at 7 V bias). Analysis of the materials, electrical and EL investigations point to the role of a high quality of p-n nano-heterojunction which facilitates a large rectification ratio (320) and a stable reverse current of 2.8 µA (1.4 × 10(-3) A cm(-2) at 5 V). Stability of EL characteristics was investigated in detail. EL intensity showed systematic degradation over a short duration when the LED was bias-stressed at 30 V. At smaller bias (<20 V) LEDs tend to show a stable and repeatable EL characteristic. Thus a simple low temperature solution growth method was successfully exploited to realize nanorod/film heterojunction LED devices with predictable characteristics.

Construct hierarchical superhydrophobic silicon surfaces by chemical etching.

We present a simple approach for preparing hydrophobic silicon surfaces by constructing silicon nanowire arrays using Ag-assisted chemical etching without low-surface-energy material modification. The static and dynamic wetting properties of the nanostructured surfaces and their dependence on etching conditions were studied. It was revealed that the surface topologies of silicon nanowire arrays and their corresponding wetting properties could be tuned by varying the etching time. Under optimized etching conditions, superhydrophobic surfaces with an apparent contact angle larger than 150 degrees and a sliding angle smaller than 10 degrees were achieved due to the formation of a hierarchical structure. The origin of hydrophobic behavior was discussed based on Wenzel and Cassie models. In addition, the effects of surface modification of Si surface nanostructures on their hydrophobic characteristics were also investigated.

Investigation of low-resistivity from hydrogenated lightly B-doped diamond by ion implantation.

We have implanted boron (B) ions (dosage: 5×1014 cm-2) into diamond and then hydrogenated the sample by implantating hydrogen ions at room temperature. A p-type diamond material with a low resistivity of 7.37 mΩ cm has been obtained in our experiment, which suggests that the hydrogenation of B-doped diamond results in a low-resistivity p-type material. Interestingly, inverse annealing, in which carrier concentration decreased with increasing annealing temperature, was observed at annealing temperatures above 600 °C. In addition, the formation mechanism of a low-resistivity material has been studied by density functional theory calculation using a plane wave method.

Carbon Dots as Fillers Inducing Healing/Self-Healing and Anticorrosion Properties in Polymers.

Self-healing is the way by which nature repairs damage and prolongs the life of bio entities. A variety of practical applications require self-healing materials in general and self-healing polymers in particular. Different (complex) methods provide the rebonding of broken bonds, suppressing crack, or local damage propagation. Here, a simple, versatile, and cost-effective methodology is reported for initiating healing in bulk polymers and self-healing and anticorrosion properties in polymer coatings: introduction of carbon dots (CDs), 5 nm sized carbon nanocrystallites, into the polymer matrix forming a composite. The CDs are blended into polymethacrylate, polyurethane, and other common polymers. The healing/self-healing process is initiated by interfacial bonding (covalent, hydrogen, and van der Waals bonding) between the CDs and the polymer matrix and can be optimized by modifying the functional groups which terminate the CDs. The healing properties of the bulk polymer-CD composites are evaluated by comparing the tensile strength of pristine (bulk and coatings) composites to those of fractured composites that are healed and by following the self-healing of scratches intentionally introduced to polymer-CD composite coatings. The composite coatings not only possess self-healing properties but also have superior anticorrosion properties compared to those of the pure polymer coatings.

Studying the growth of cubic boron nitride on amorphous tetrahedral carbon interlayers.

The growth of cubic boron nitride (cBN) films on bare silicon and amorphous tetrahedral carbon (ta-C) layers prepared on silicon substrates was studied. The cBN films were prepared by radio frequency magnetron sputter deposition at approximately 870 degrees C. The original ta-C interlayers were graphitized and restructured under high temperature and possibly under ion bombardment during BN deposition. The majority of graphitic basal planes were nearly perpendicular to the surface of silicon substrates. The BN films grown on these restructured carbon layers were deposited with higher content of cubic phase and did not show delamination signs. Turbostratic BN (tBN) basal planes extended carbon basal planes and their edges served as cBN nucleation sites. The cBN films grown on textured ta-C interlayers were insensitive to the ambient environment. The residual sp(3)-bonded carbon phase confined in the interlayers probably acts as a diffusion barrier preventing the oxidation of dangling bonds near BN interface and thus precludes weakening the interface as a result of volume expansion. The carbon interlayers also improve the crystallinity of the oriented tBN because they are continuation of carbon graphitic basal planes so that the volume fraction of nitrogen-void (N-void) defects in the sp(2)-bonded BN intermediate layers is reduced. The strong sp(3)-bonded carbon matrix could thereto withstand large compressive stress and facilitates deposition of thicker cBN films.

Facile and fast synthesis of porous TiO2 spheres for use in lithium ion batteries.

Porous anatase TiO2 spheres have been synthesized by a microwave-assisted hydrothermal reaction of spherical particle precursors followed by annealing in air. The synthesized TiO2 spheres are formed by interconnected nanocrystals with size of 8.7 nm in average and have grain diameters of 250-400 nm. After annealing at 500°C, the TiO2 samples maintain spherical shape and develop highly mesoporous characteristics with a specific surface area of 151 m(2) g(-1). The TiO2 samples annealed at 750°C consist of larger aggregated particles with diameters of 500-900 nm and still retain mesoporous anatase structure, but with a reduced specific surface area of 25.6 m(2) g(-1). Electrochemical studies reveal that the porous TiO2 spheres annealed at 500°C own very high and stable lithium ion (Li(+)) storage capacities of 207, 184, 166, and 119 mA h g(-1) at 0.5, 1, 2, and 5C (850 mA g(-1)) rates, respectively, owing to their highly porous nanostructures and fine spherical morphology. In contrast, the TiO2 spheres annealed at 700°C exhibit modest electrochemical performance due to their reduced pore structures and larger crystallite size. The prepared porous TiO2 spherical particles show great promise for use as high performance anode materials for lithium ion batteries (LIBs).

Facile synthesis of hierarchical and porous V2O5 microspheres as cathode materials for lithium ion batteries.

Hierarchical and porous V2O5 microspheres have been fabricated by a refluxing approach followed by annealing in air. The resulting porous V2O5 microspheres typically have diameters of 3-6 µm and are constructed of intertwined laminar nanocrystals or crosslinked nanobricks. It is found that the vanadyl glycolates rinsed with water have pronounced pore structures than that rinsed with ethanol alone. In addition, the configuration of the vanadyl glycolates microspheres can be tuned during the refluxing along with stirring. The possible formation processes of the vanadyl glycolates and V2O5 products have been discussed based on the experimental data. Electrochemical tests indicate that the hierarchical and porous V2O5 microspheres exhibit relatively high and stable Li(+) storage properties. The porous V2O5 microspheres assembled by intertwined nanoparticles maintain reversible Li(+) storage capacities of 102 and 80 mAh g(-1), respectively; whilst the porous V2O5 microspheres assembled by crosslinked nanobricks maintain reversible Li(+) storage capacities of 100 and 85 mAh g(-1) over 100 cycles at current rates of 0.5 and 1 C, respectively. The superior Li(+) storage performance of the hierarchical and porous V2O5 microspheres could mainly be ascribed to the improved electrode/electrolyte interface, reduced Li(+) diffusion paths, and relieved volume variation during lithiation and delithiation processes.

Visible-NIR photodetectors based on CdTe nanoribbons.

Zinc blende-structured CdTe nanoribbons (NRs) were synthesized for the first time via a two-step process. The electronic, transport, and photoconductive properties of the CdTe NRs were studied systematically. It was revealed that the CdTe NRs showed p-type conductivity, and presented significant photoresponses to visible-NIR (400-800 nm) irradiation with high responsivity and gain. The contribution of the factors such as surface states of NRs, channel length, light intensity, and working bias voltage to the photoresponse characteristics of CdTe NR photodetectors were discussed. Moreover, single CdTe NR-based visible-NIR photodetectors were also demonstrated to have high stability and reliability.

Tunable band gaps and p-type transport properties of boron-doped graphenes by controllable ion doping using reactive microwave plasma.

We report tunable band gaps and transport properties of B-doped graphenes that were achieved via controllable doping through reaction with the ion atmosphere of trimethylboron decomposed by microwave plasma. Both electron energy loss spectroscopy and X-ray photoemission spectroscopy analyses of the graphene reacted with ion atmosphere showed that B atoms are substitutionally incorporated into graphenes without segregation of B domains. The B content was adjusted over a range of 0-13.85 atom % by controlling the ion reaction time, from which the doping effects on transport properties were quantitatively evaluated. Electrical measurements from graphene field-effect transistors show that the B-doped graphenes have a distinct p-type conductivity with a current on/off ratio higher than 10(2). Especially, the band gap of graphenes is tuned from 0 to ~0.54 eV with increasing B content, leading to a series of modulated transport properties. We believe the controllable doping for graphenes with predictable transport properties may pave a way for the development of graphene-based devices.

Tunable p-type conductivity and transport properties of AlN nanowires via Mg doping.

Arrays of well-aligned AlN nanowires (NWs) with tunable p-type conductivity were synthesized on Si(111) substrates using bis(cyclopentadienyl)magnesium (Cp(2)Mg) vapor as a doping source by chemical vapor deposition. The Mg-doped AlN NWs are single-crystalline and grow along the [001] direction. Gate-voltage-dependent transport measurements on field-effect transistors constructed from individual NWs revealed the transition from n-type conductivity in the undoped AlN NWs to p-type conductivity in the Mg-doped NWs. By adjusting the doping gas flow rate (0-10 sccm), the conductivity of AlN NWs can be tuned over 7 orders of magnitude from (3.8-8.5) × 10(-6) Ω(-1) cm(-1) for the undoped sample to 15.6-24.4 Ω(-1) cm(-1) for the Mg-doped AlN NWs. Hole concentration as high as 4.7 × 10(19) cm(-3) was achieved for the heaviest doping. In addition, the maximum hole mobility (∼6.4 cm(2)/V s) in p-type AlN NWs is much higher than that of Mg-doped AlN films (∼1.0 cm(2)/V s). (2) The realization of p-type AlN NWs with tunable electrical transport properties may open great potential in developing practical nanodevices such as deep-UV light-emitting diodes and photodetectors.

Incorporation of graphenes in nanostructured TiO(2) films via molecular grafting for dye-sensitized solar cell application.

This paper presents a systematic investigation on the incorporation of chemical exfoliation graphene sheets (GS) in TiO(2) nanoparticle films via a molecular grafting method for dye-sensitized solar cells (DSSCs). By controlling the oxidation time in the chemical exfoliation process, both high conductivity of reduced GS and good attachment of TiO(2) nanoparticles on the GS were achieved. Uniform GS/TiO(2) composite films with large areas on conductive glass were prepared by electrophoretic deposition, and the incorporation of GS significantly improved the conductivity of the TiO(2) nanoparticle film by more than 2 orders of magnitude. Moreover, the power conversion efficiency for DSSC based on GS/TiO(2) composite films is more than 5 times higher than that based on TiO(2) alone, indicating that the incorporation of GS is an efficient means for enhancing the photovoltaic (PV) performance. The better PV performance of GS/TiO(2) DSSC is also attributed to the better dye loading of GS/TiO(2) film than that of TiO(2) film. The effect of GS content on the PV performances was also investigated. It was found that the power conversion efficiency increased first and then decreased with the increasing of GS concentration due to the decrease in the transmittance at high GS content. Further improvements can be expected by fully optimizing fabrication conditions and device configuration, such as increasing dye loading via thicker films. The present synthetic strategy is expected to lead to a family of composites with designed properties.

Calcinosis tumoral: una rara entidad en hiperparatiroidismo terciario

Objetivo: La calcinosis tumoral es un desorden infrecuente caracterizado por el desarrollo de masas calcificadas en los tejidos periarticulares de las articulaciones. Se presenta caso representativo. Caso Clínico: Se presenta el caso de una paciente femenina de 34 años con enfermedad renal crónica e hiperparatiroidismo terciario quien presentó un tumor de 40 x 20 cm aproximadamente en la cadera derecha y 10 x 10 cm en la cadera izquierda, ambos sólidos, pétreos, no móviles y poco dolorosos, de 1 año de evolución. Bioquímica sanguínea reveló hiperfosfatemia, hipercalcemia y PTH 1125 pg/mL. En radiografías se apreció calcificación prominente en ambas caderas principalmente la derecha. El tratamiento ofrecido fue paratiroidectomía con autoimplante. Conclusión: La calcinosis tumoral es un síndrome de calcificación ectópica infrecuente y puede ser una rara complicación del hiperparatiroidismo terciario y de la enfermedad renal crónica.

Objective: The tumoral calcinosis is an infrequent disorder characterized by the development of calcified masses within the peri-articular soft tissues of large joints. A representative case is presented. Case presentation: We present a case of a woman patient of 34 years old with chronic renal failure and tertiary hyperparathyroidism who presented a solid tumor of 40 x 20 cm approximately in the right hip and a tumor of 10 x 10 cm in the left hip, stony, nonmovable and little painful since 1 year ago. Blood biochemistry revealed hyperphosphatemia, hypercalcemia and PTH 1125 pg/mL. In x-rays prominent calcification in both hips was appraised mainly the right. The offered treatment was parathyroidectomy with autoimplant. Conclusion: Tumoral calcinosis is an uncommon ectopic calcification syndrome and may be a rare complication of tertiary hyperparathyroidism and chronic renal failure.

Calcinosis tumoral: una rara entidad en hiperparatiroidismo terciario / Tumoral calcinosis: a rare entity in tertiary hyperparathyroidism

La calcinosis tumoral es un desorden infrecuente caracterizado por el desarrollo de masas calcificadas en los tejidos periarticulares de las articulaciones. Presentación del caso: se presenta un caso de una paciente femenina de 34 años con enfermedad renal crónica e hiperparatiroidismo terciario quien presentó un tumor de 40 x 20 cm aproximadamente en la cadera derecha y 10 x 10 cm cadera izquierda, ambos sólidos, pétreos, no móviles y poco doloroso de 1 año de evolución. La bioquímica sanguínea reveló hiperfosfatemia, hipercalcemia y PTH 1125 pg/ml. En las radiografías se apreció calcificación prominente en ambas caderas, principalmente la derecha. El tratamiento ofrecido fue paratiroidectomía con autoimplante. Conclusión: la calcinosis tumoral es un síndrome de calcificación ectópica infrecuente y puede ser una rara complicación del hiperparatiroidismo terciario y de la enfermedad renal crónica(AU)

The tumoral calcinosis is an infrequent disorder characterized by the development of calcified masses within the peri-articular soft tissues of large joints. Case presentation: we present a case of a woman patient of 34 years old with chronic renal failure and tertiary hyperparathyroidism, who presented a solid tumor from 40 x 20 cm approximately in the right hip and a tumor of 10 x 10 cm in left hip, stony, nonmovable and little painful from 1 year ago. Blood biochemistry revealed hyperphosphatemia, hypercalcemia and PTH 1125 pg/ml. In x-rays prominent calcification in both hips was appraised mainly the right. The offered treatment was parathyroidectomy with autoimplant. Conclusion: Tumor calcinosis is an uncommon ectopic calcification syndrome and it is can a rare complication of tertiary hyperparathyroidism and chronic renal failure(AU)

Hiperparatiroidismo terciario: a propósito de tres pacientes con complicaciones diferentes / Tertiary hyperparathyroidism: representation of the complications in three different cases

El hiperparatiroidismo terciario ha sido reconocido como una hiperfunción autónoma de las glándulas paratiroides. Cuando esta enfermedad se instaura, la única opción terapéutica efectiva es la paratiroidectomía. Estos pacientes frecuentemente tienen hiperplasia paratiroidea por lo que la exploración cervical debe ser bilateral. Presentación de casos: Presentamos 3 pacientes, cada uno con una complicación diferente a propósito del hiperparatiroidismo terciario. La primera paciente con arteriolopatía cálcico-urémica, la segunda con calcinosis tumoral de la cadera, y la tercera paciente con tumor pardo bimaxilar. A todos los pacientes los tratamos con paratiroidectomía total con auto trasplante de la glándula más sana en el músculo recto anterior del abdomen. El estudio anatomopatológico reveló hiperplasia de las glándulas paratiroideas resecadas en todos los pacientes. La complicación principal de este procedimiento fue la hipocalcemia sintomática, requiriendo infusión de calcio endovenoso. Dos pacientes presentaron síndrome de hueso hambriento, que se resolvió progresivamente y en el seguimiento se observó normocalcemia. Hubo desenlace fatal en 2 pacientes como consecuencia de complicaciones sistémicas. El hiperparatiroidismo terciario es una enfermedad rara que el clínico debe reconocer para tratarla oportunamente. La paratiroidectomía total es terapéuticamente efectiva en esta condición, pero la hipocalcemia profunda posoperatoria es frecuente y necesita de un manejo cuidadoso.

Tertiary hyperparathyroidism has been recognized as an autonomous hyperfunction of the parathyroid glands. When this disease is established, the only effective therapeutic option is parathyroidectomy. These patients often have parathyroid hyperplasia so that the the neck exploration must be bilateral. Cases presentation: We report 3 patients, each with a different complication as a consequence of tertiary hyperparathyroidism. The first patient with calcic uremic arteriolopathy, the second with tumoral calcinosis of the hip, and the third patient with bimaxillary brown tumor. We treated all this patients with total parathyroidectomy, followed by healthy gland autotransplantation in the anterior rectus abdominal muscle. The anatomopathological study revealed hyperplasia of the resected parathyroid glands, in all the specimens. The main complication of this procedure were the symptomatic hypocalcemia, requiring intravenous calcium infusion. Two patients had the hungry bone syndrome, which was solved progressively. Two parients died due to systemic complications. Tertiary hyperparathyroidism is a rare disease that the clinician should recognize in order to treat it promptly. Total parathyroidectomy is therapeutically effective in this condition, but the postoperative profound hypocalcemia is frequent and needs a careful management.

Cubic phase content and structure of BN films from an X-ray absorption study.

X-ray absorption near-edge structure (XANES) was used to study the cubic boron nitride (c-BN) content in the BN films deposited on various substrates by different physical vapor deposition or plasma-enhanced chemical vapor deposition methods. By fitting the XANES curves of thin-film samples using standard spectra of pure c-BN and sp(2)-bonded BN in the films with suitable weight factors, the c-BN contents at the film's surface region and across the film's thickness have been determined quantitatively. The results agree well with the previous transmission electron microscopic observations. The method is proved to be independent of the optical properties of thin film and provides a possibility to evaluate the cubic content of BN films accurately.

Lipoma gigante cervico -torácico. Abordaje mixto por cervicotomía y toracoscopia: Reporte de un caso / Cervico-thoracic giant lipoma: mixed approach by cervicotomy and thoracoscopy: a case report

Se presenta un caso de lipoma cervicotorácico gigante en paciente femenino de 45 años de edad, quien consultó por aumento de volumen cervical, odinodisfagia y disnea. Una radiografía de tórax y tomografía computarizada reveló una masa gigante intratorácica bilateral, ocupando la cavidad torácica izquierda con extensión al mediastino anterosuperior y al cuello, desplazando la tráquea y la faringe hacia la porción anterior y derecha. La paciente se llevó a resección quirúrgica del tumor cervico-torácico, con examen histológico que confirmó el diagnóstico de un lipoma gigante, con peso de 475 gramos y medidas de 30 x 20 cm. Este es el lipoma cervico-torácico más grande documentado en la literatura moderna y con abordaje mixto cervicotomía más toracoscopia

Female patient 45 years old with giant cervicothoracic lipoma, that consulted by increase of cervical volume, odinodysphagia and dyspnea. An x-ray thorax and computerized tomography revealed a bilateral intrathoracic giant mass, occupying the left thoracic cavity extending to the anterosuperior mediastinum and the neck, causing displacement of the trachea and the pharynx towards the previous and right portion. The patient took to surgical resection of the cervical thoracic tumor, with histological examination that confirmed the diagnosis of a giant lipoma, with weight of 475 grams and measures of 30 x 20 cm. It is largest cervical thoracic lipoma documented in modern literature and with cervicotomy and thoracoscopic approach