Synthesis and surface modification of zno nanoparticles

ZnO nanoparticles have been synthesized by precipitation method from Zinc nitrate. The powder was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, selected-area electron diffraction, UV-vis optical absorption, and photoluminescence spectroscopy analyses. XRD patterns showed that ZnO nanoparticles have hexagonal unit cell structure. SEM and TEM pictures reveal the morphology and particle size of prepared ZnO nanoparticles. The UV-vis absorption spectrum shows an absorption band at 355 nm due to ZnO nanoparticles. The photoluminescence spectrum exhibits two emission peaks one at 392 nm corresponding to band gap excitonic emission and another located at 520 nm due to the presence of singly ionized oxygen vacancies. The synthesis method has potential for application in manufacturing units due to ease processing and more economical reagents.

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Synthesis, Characterization, and Spectroscopic Properties of ZnO Nanoparticles

Analysis of crack behavior for Ni-based WC composite coatings by laser cladding and crack-free realization

Cloud Computing represents a new computing model that poses many demanding security issues at all levels, e.g., network, host, application, and data levels. The variety of the delivery models presents different security challenges depending on the model and consumers' Quality of Service (QoS) requirements. Confidentiality, Integrity, Availability, Authenticity, and Privacy are essential concerns for both Cloud providers and consumers as well. Infrastructure as a Service (IaaS) serves as the foundation layer for the other delivery models, and a lack of security in this layer will certainly affect the other delivery models, i.e., PaaS, and SaaS that are built upon IaaS layer. This paper presents an elaborated study of IaaS components' security and determines vulnerabilities and countermeasures. Finally, as a result of this research, we propose a Security Model for IaaS (SMI) to guide security assessment and enhancement in IaaS layer.

Infrastructure as a service security: Challenges and solutions

Nanoparticles of zinc oxide (ZnO) are increasingly recognized for their utility in biological applications. In this study, the high-energy ball milling (HEBM) technique was used to produce nanoparticles of ZnO from its microcrystalline powder. Four samples were ball milled for 2, 10, 20, and 50 hours, respectively. The structural and optical modifications induced in the 'as synthesized' nanomaterials were determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), and photoluminescence emission spectra (PL). SEM and TEM results show a gradual decrease in particle size from around 600 to ∼30 nm, with increased milling time. The initial microstructures had random shapes, while the final shape became quite spherical. XRD analysis showed ZnO in a hexagonal structure, broadening in the diffracted peaks and going from larger to smaller particles along with a relaxation in the lattice constant c. The value of c was found to increase from 5.204 to 5.217 A with a decrease in particle size (600 to ∼30 nm). PL result showed a new band at around 365 nm, whose intensity is found to increase as the particles size decreases. These remarkable structural and optical modifications induced in ZnO nanoparticles might prove useful for various applications. The increase in c value is an important factor for increasing the antibacterial effects of ZnO, suggesting that the HEBM technique is quite suitable for producing these nanoparticles for this purpose.

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High-energy ball milling technique for ZnO nanoparticles as antibacterial material.

Influence of Mo content on microstructure and mechanical properties of high strength pipeline steel

Varistors based on ZnO–lead zinc borosilicate glass were prepared from tetrapod ZnO nanopowders, every one of which had four needle-like legs and each one was about 20 nm or less in diameter and from several hundreds of nanometers to several micrometers in length by the method of direct co-sintering synthesis of oxides instead of adding amorphous lead zinc borosilicate frit. The compact green disks were conventionally sintered in air for 2 h at a temperature of 900–1170 °C. The varistors with nonlinear coefficient α=38.7 and leakage current IL=1.7 μA were obtained. The results showed that the sintering temperature was lowered to 900 °C, and there was very little influence of the sintering temperature on the nonlinear coefficient α at a range 900–1170 °C.

Preparation of ZnO-glass varistor from tetrapod ZnO nanopowders

The laser cladding of self-fluxing Fe–Cr–Ni alloys on a medium carbon steel substrate was performed using a CO 2 laser and Ar shielding gas that was blown into a molten pool. The cracking susceptibility and microstructure of the laser-clad layer were studied in terms of Co additions. Co can change the microstructure of a Fe–Cr–Ni alloy clad layer from eutectic to hypoeutectic and decrease the cracking susceptibility of clad layers. However, these results relate not only to the Co content in the laser-clad alloys, but also the number of overlapping tracks. With the increment of Co content in clad layer, the cracking susceptibility of the laser cladding layer decreases and the number of overlapping tracks with hypoeutectic structure increases. At the same time, Co does not change the hardness of the clad layer.

Effects of Co on the cracking susceptibility and the microstructure of Fe–Cr–Ni laser-clad layer

The iSCSI protocol enables the access to SCSI devices over an IP network.The SCSI command descriptor blocks are encapsulated in the iSCSI protocol data unit and transferred by the TCP/IP protocol.The overhead of the iSCSI protocol is relatively high,and the performance of iSCSI is limited by the network maximum transmission unit and the iSCSI protocol parameters.

A Performance Analysis of the iSCSI Protocol

An investigation is reported of the laser surface cladding of self-fluxing Fe–Cr–Ni–B––Si alloys on a medium carbon steel substrate using the preplaced powder method. The cracking susceptibility of the laser-clad layer has been studied in terms of the melting properties of the cladded alloy. The smaller the fusion temperature zone and fusion-end temperature of the cladded alloy, the lower the cracking susceptibility of the laser-clad layer. The effect of the latent heat of fusion of the cladded alloy on cracking susceptibility is not apparent.

Xie Changsheng

Papers

Influence of Mo content on microstructure and mechanical properties of high strength pipeline steel

Preparation of ZnO-glass varistor from tetrapod ZnO nanopowders

Effects of Co on the cracking susceptibility and the microstructure of Fe–Cr–Ni laser-clad layer

A Performance Analysis of the iSCSI Protocol

Cracking susceptibility of a laser-clad layer as related to the melting properties of the cladding alloy