There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Molecular self-assembly is the spontaneous association of molecules under equilibrium conditions into stable, structurally well-defined aggregates joined by noncovalent bonds. Molecular self-assembly is ubiquitous in biological systems and underlies the formation of a wide variety of complex biological structures. Understanding self-assembly and the associated noncovalent interactions that connect complementary interacting molecular surfaces in biological aggregates is a central concern in structural biochemistry. Self-assembly is also emerging as a new strategy in chemical synthesis, with the potential of generating nonbiological structures with dimensions of 1 to 10(2) nanometers (with molecular weights of 10(4) to 10(10) daltons). Structures in the upper part of this range of sizes are presently inaccessible through chemical synthesis, and the ability to prepare them would open a route to structures comparable in size (and perhaps complementary in function) to those that can be prepared by microlithography and other techniques of microfabrication.

Molecular self-assembly and nanochemistry: A chemical strategy for the synthesis of nanostructures

Zinc oxide can be called a multifunctional material thanks to its unique physical and chemical properties. The first part of this paper presents the most important methods of preparation of ZnO divided into metallurgical and chemical methods. The mechanochemical process, controlled precipitation, sol-gel method, solvothermal and hydrothermal method, method using emulsion and microemulsion enviroment and other methods of obtaining zinc oxide were classified as chemical methods. In the next part of this review, the modification methods of ZnO were characterized. The modification with organic (carboxylic acid, silanes) and inroganic (metal oxides) compounds, and polymer matrices were mainly described. Finally, we present possible applications in various branches of industry: rubber, pharmaceutical, cosmetics, textile, electronic and electrotechnology, photocatalysis were introduced. This review provides useful information for specialist dealings with zinc oxide.

Zinc Oxide-From Synthesis to Application: A Review.

Fiber-based structures are highly desirable for wearable electronics that are expected to be light-weight, long-lasting, flexible, and conformable Many fibrous structures have been manufactured by well-established lost-effective textile processing technologies, normally at ambient conditions The advancement of nanotechnology has made it feasible to build electronic devices directly on the surface or inside of single fibers, which have typical thickness of several to tens microns However, imparting electronic functions to porous, highly deformable and three-dimensional fiber assemblies and maintaining them during wear represent great challenges from both views of fundamental understanding and practical implementation This article attempts to critically review the current state-of-arts with respect to materials, fabrication techniques, and structural design of devices as well as applications of the fiber-based wearable electronic products In addition, this review elaborates the performance requirements of the fiber-based wearable electronic products, especially regarding the correlation among materials, fiber/textile structures and electronic as well as mechanical functionalities of fiber-based electronic devices Finally, discussions will be presented regarding to limitations of current materials, fabrication techniques, devices concerning manufacturability and performance as well as scientific understanding that must be improved prior to their wide adoption

Fiber‐Based Wearable Electronics: A Review of Materials, Fabrication, Devices, and Applications

Photocatalytic properties of different morphologies of CuO for the degradation of Congo red organic dye

ZnO nanorods with excellent optical and electro-optical emission characteristics were grown using high- and low-temperature techniques on solid and soft substrate materials. The solid crystalline substrates included p-4H-SiC and p-GaN, while the soft amorphous substrates included p-type polymers deposited on glass and flexible plastic. Two different growth approaches were used to produce these samples. We used the vapor–liquid–solid (VLS) technique (high temperature) and aqueous chemical growth (ACG), which is a low-temperature technique. These ZnO nanorod samples were characterized by room temperature photoluminescence (PL) and processed to fabricate light-emitting diodes (LEDs). The LED characteristics were further investigated by I–V and electroluminescence (EL). As observed by PL measurements, all samples revealed a sharp narrow ultraviolet (UV) peak due to band-edge emission, indicating the good crystalline quality of the grown ZnO nanorods. The origin of the different peaks within the visible region was correlated to different deep level defects reported earlier for ZnO. All fabricated LEDs showed EL providing a wide band extended through the whole visible spectrum and hence produced clear white light observable to the naked eye. The emitted color quality investigation showed that superior color quality was manifested in a high color rendering index and stable color under current variation, indicating that these heterojunction and hybrid LEDs have potential for the development of future light sources. The ZnO nanorod-based LEDs grown by low-temperature ACG on glass and flexible plastic can, after further development, be candidates for future large-area white-light sources.

/pdf/zinc-oxide-nanorod-based-heterostructures-on-solid-and-soft-uiwd79hm4n.pdf

Zinc oxide nanorod-based heterostructures on solid and soft substrates for white-light-emitting diode applications

We demonstrate the synthesis and investigate the electrical and optical characteristics of ‘nanocorals’ (NCs) composed of CuO/ZnO grown at low temperature through the hydrothermal approach. High-density CuO nanostructures (NSs) were selectively grown on ZnO nanorods (NRs). The synthesized NCs were used to fabricate p–n heterojunctions that were investigated by the current density–voltage (J–V) and the capacitance–voltage (C–V) techniques. It was found that the NC heterojunctions exhibit a well-defined diode behavior with a threshold voltage of about 1.52 V and relatively high rectification factor of ∼760. The detailed forward J–V characteristics revealed that the current transport is controlled by an ohmic behavior for V≤0.15 V, whereas at moderate voltages 1.46≤V<1.5 the current follows a J α exp(βV) relationship. At higher voltages (≥1.5 V) the current follows the relation J α V2, indicating that the space-charge-limited current mechanism is the dominant current transport. The C–V measurement indicated that the NC diode has an abrupt junction. The grown CuO/ZnO NCs exhibited a broad light absorption range that is covering the UV and the entire visible parts of the spectrum.

/pdf/optical-and-current-transport-properties-of-cuo-zno-1qf3s3ng7j.pdf

Optical and current transport properties of CuO/ZnO nanocoral p–n heterostructure hydrothermally synthesized at low temperature

Cheap and efficient white light-emitting diodes (LEDs) are of great interest due to the energy crisis all over the world. Herein, we have developed heterojunction LEDs based on the well-aligned ZnO nanorods and nanotubes on the p-type GaN with the insertion of the NiO buffer layer that showed enhancement in the light emission. Scanning electron microscopy have well demonstrated the arrays of the ZnO nanorods and the proper etching into the nanotubes. X-ray diffraction study describes the wurtzite crystal structure array of ZnO nanorods with the involvement of GaN at the (002) peak. The cathodoluminescence spectra represent strong and broad visible emission peaks compared to the UV emission and a weak peak at 425 nm which is originated from GaN. Electroluminescence study has shown highly improved luminescence response for the LEDs fabricated with NiO buffer layer compared to that without NiO layer. Introducing a sandwich-thin layer of NiO between the n-type ZnO and the p-type GaN will possibly block the injection of electrons from the ZnO to the GaN. Moreover, the presence of NiO buffer layer might create the confinement effect.

/pdf/the-fabrication-of-white-light-emitting-diodes-using-the-n-1nelofz6v4.pdf

The fabrication of white light-emitting diodes using the n-ZnO/NiO/p-GaN heterojunction with enhanced luminescence

Zinc oxide (ZnO) with its deep level defect emission covering the whole visible spectrum holds promise for the development of intrinsic white lighting sources with no need of using phosphors for light conversion. ZnO nanorods (NRs) grown on flexible plastic as substrate using a low temperature approach (down to 50 °C) were combined with different organic semiconductors to form hybrid junction. White electroluminescence (EL) was observed from these hybrid junctions. The configuration used for the hybrid white light emitting diodes (LEDs) consists of two-layers of polymers on the flexible plastic with ZnO NRs on the top. The inorganic/organic hybrid heterojunction has been fabricated by spin coating the p-type polymer poly (3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT : PSS) for hole injection with an ionization potential of 5.1 eV and poly(9, 9-dioctylfluorene) (PFO) is used as blue emitting material with a bandgap of 3.3 eV. ZnO NRs are grown on top of the organic layers. Two other configurations were also fabricated; these are using a single MEH PPV (red-emitting polymer) instead of the PFO and the third configuration was obtained from a blend of the PFO and the MEH PPV. The white LEDs were characterized by scanning electron microscope, x-ray diffraction (XRD), current–voltage (I–V) characteristics, room temperature photoluminescence (PL) and EL. The EL spectrum reveals a broad emission band covering the range from 420 to 800 nm, and the emissions causing this white luminescence were identified.

/pdf/zinc-oxide-nanorods-polymer-hybrid-heterojunctions-for-white-4k4xxxvhku.pdf

Omer Nur

Papers

Photocatalytic properties of different morphologies of CuO for the degradation of Congo red organic dye

Zinc oxide nanorod-based heterostructures on solid and soft substrates for white-light-emitting diode applications

Optical and current transport properties of CuO/ZnO nanocoral p–n heterostructure hydrothermally synthesized at low temperature

The fabrication of white light-emitting diodes using the n-ZnO/NiO/p-GaN heterojunction with enhanced luminescence

Zinc oxide nanorods/polymer hybrid heterojunctions for white light emitting diodes