The toxic effects of microcystin-LR on embryo-larval and juvenile development of loach, Misguruns mizolepis Gunthe

Microcystin-LR, a specific and potent hepatotoxin, was tested for its effects oil loach embryo-larval and juvenile development, The results of this study showed that loach embryos were more sensitive when exposed to microcystin-LR at a later than at an earlier stage of development, Juveniles were far less sensitive to MC-LR than were embryos and larvae. Mortality and developmental abnormality were proven to be dose-dependent and to be stage-specific sensitive. Among the abnormal changes noted were: pericardial edema and tubular heart, bradycardia, homeostasis, poor yolk resumption. small head, curved body and tail, and abnormal hatching, Liver and heart were the main targets of microcystin-LR toxicity. Ultrastructural analysis documented a complex set of sublethal effects of microcystin-LR on loach hepatocytes, chiefly including morphological alteration in nuclear and RER of loach liver cells. fit addition, microcystin-LR was lethal to loach juvenile in the subacute (7 days) exposure (LC50) = 593.3 mug/l). (C) 2002 Elsevier Science Ltd. All rights reserved.

Isolation of a lethal rhabdovirus from the cultured Chinese sucker Myxocyprinus asiaticus

A rhabdovirus was found to be associated with a lethal hemorrhagic disease in the cultured Chinese sucker Myxocyprinus asiaticus Bleeker. The rhabdovirus was amplified and isolated from the infected GCO, (grass carp ovary) cells. In ultrathin sections of liver cells from the diseased fish, the virus particles exhibited the characteristic bacilliform morphology, and budded through vesicle membranes of the infected cells. The isolated rhabdovirus particles were found to have a bacilliform morphology with 2 rounded ends rather than a typical flat base. The virus particles were measured and ranged in size from 150 to 200 nm in length and 50 to 60 nm in diameter. Most other characteristics, including their size, extensive virus infectivity to fish cell Lines, strong cytopathogenic effects, stability at high temperatures, vesicle formation in infected cells, structure protein electrophoretic patterns and the presence of an RNA genome, very closely resembled those of other fish rhabdoviruses. At present it is not known if this is a novel virus species or if it is an isolate of a known fish rhabdovirus. Until a confirmed identification can be made, we will temporarily refer to this virus as Chinese sucker rhabdovirus (CSRV).

Fabrication of a Low-Loss SSC Using High-Dose Electron Beam Lithography Exposure With Negative PMMA Resist

A silicon-on-insulator optical fiber-to-waveguide spot-size converter (SSC) using Poly-MethylMethAcrylate (PMMA) is presented for integrated optical circuits. Unlike the conventional use of PMMA as a positive resist, it has been successfully used as a negative resist with high-dose electron exposure for the fabrication of ultrafine silicon wire waveguides. Additionally, this process is able to reduce the side-wall roughness, and substantially depresses the unwanted propagation loss. Exploiting this technology, the authors demonstrated that the SSC can improve coupling efficiency by as much as over 2.5 dB per coupling facet, compared with that of SSC fabricated with PMMA as a positive resist with the same dimension.

Effects of indium ion implantation on the total dose hardness of fully depleted SOI NMOSFET

In this work, we investigate the effects of the indium ion implantation towards the back-channel interface on the total dose hardness of the n-channel SOI MOSFET. The results show that the indium implant has slight impact on the normal threshold voltage while preserving low leakage current after irradiation. The advantage is attributed to the narrow as-implanted and postanneal profile of the indium implantation. Two-dimensional simulations have been used to understand the physical mechanisms of the effects.

The impact of implantation dose on the characteristics of diluted-magnetic nonpolar GaN:Cu films

Diluted-magnetic nonpolar GaN:Cu films have been fabricated by implanting Cu ions into p-type nonpolar a-plane (1120) GaN films with a subsequent thermal annealing process. The impact of the implantation dose on the structural. morphological and magnetic characteristics of the samples have been investigated by means of high-resolution X-ray diffraction (HRXRD). atomic force microscopy (AFM), and superconducting quantum interference device (SQUID). The XRD and AFM analyses show that the structural and morphological characteristics of samples deteriorated with the increase of implantation dose. According to the SQUID analysis. obvious room-temperature ferromagnetic properties of samples were detected. Moreover, the saturation magnetization per Cu atom decreased as the implantation dose increased. (C) 2009 Elsevier B.V. All rights reserved.

Silicon-on-insulating multi-layers for total-dose irradiation hardness

Silicon-on-insulating multi-layer (SOIM) materials were fabricated by co-implantation of oxygen and nitrogen ions with different energies and doses. The multilayer microstructure was investigated by cross-sectional transmission electron microscopy. P-channel metal-oxide-semiconductor (PMOS) transistors and metal-semiconductor-insulator-semiconductor (MSIS) capacitors were produced by these materials. After the irradiated total dose reaches 3 x 10(5) rad (Si), the threshold voltage of the SOIM-based PMOS transistor only shifts 0.07 V, while thin silicon-on-insulating buried-oxide SIMOX-based PMOS transistors have a shift of 1.2V, where SIMOX represents the separated by implanted oxygen. The difference of capacitance of the SOIM-based MSIS capacitors before and after irradiation is less than that of the thin-box SIMOX-based MSIS capacitor. The results suggest that the SOIM materials have a more remarkable irradiation tolerance of total dose effect, compared to the thin-buried-oxide SIMOX materials.

Formation of total-dose-radiation hardened materials by sequential oxygen and nitrogen implantation and multi-step annealing

Separation by implantation of oxygen and nitrogen (SIMON) silicon-on-insulator (SOI) materials were fabricated by sequential oxygen and nitrogen implantation with annealing after each implantation. Analyses of SIMS, XTEM and HRTEM were performed. The results show that superior buried insulating multi-layers were well formed and the possible mechanism is discussed. The remarkable total-dose irradiation tolerance of SIMON materials was confirmed by few shifts of drain leakage current-gate source voltage (I-V) curves of PMOS transistors fabricated on SIMON materials before and after irradiation.

Fabrication of metallic air bridges using multiple-dose electron beam lithography

The techniques of fabricating metallic air bridges using different resists in a one-step electron beam lithography are presented. The exposure process employed a single-layer polymethyl methacrylate (PMMA) or photoresists with either different doses in the span and feet areas or with varying acceleration voltage of the electron beam. The process using photoresists with different doses has produced air bridges more stable than what the PMMA method using various acceleration voltages would achieve. Using this method, air bridges up to 12 mu m long have been fabricated. The length and height of these metallic air bridges vary with the photoresist thickness. (c) 2006 American Institute of Physics.

Dose rate dependence of electrical characteristics of lead zirconate titanate capacitors

The influence of gamma-radiation dose rate on the electrical properties of lead zirconate titanate capacitors was investigated. More severe degradations in dielectric constant, coercive field, remanent polarization and capacitance-voltage (C-V) curves occurred with increasing radiation dose at lower dose rates. The electrical properties exhibited distinct radiation dose rate dependence and the worst-case degradation occurred at the lowest dose rate. The radiation-induced degradation of parameters such as the coercive field drift and distortion of the C-V curve can be recovered partly through post-irradiation annealing.

Aggregation and precipitation in high dose as ion implanted Ge0.5Si0.5 alloy

Thermally stimulated redistribution and precipitation of excess arsenic in Ge0.5Si0.5 alloy has been studied by X-ray photoelectron spectroscopy (XPS), cross sectional transmission electron microscopy (XTEM) and X-ray energy disperse spectrometry (EDS). Samples were prepared by the implantation of 6 X 10(6) As+ cm(-2) and 100 keV with subsequent thermal processing at 800 degrees C and 1000 degrees C for 1 h. The XPS depth profiles from the implanted samples before and after the thermal annealing indicate that there is marked redistribution of the elements in heavily arsenic-implanted Ge0.5Si0.5 alloys during the annealing, including: (1) diffusion of As from the implanted region to the surface; (2) aggregation of Ge in the vicinity of the surface. A high density of precipitates was observed near the surface which were by XTEM and EDS identified as an arsenide. It is suggested that most of the implanted As in Ge0.5Si0.5 alloy exists in the form of GeAs.

Total Dose Radiation-Hard 0. SOI CMOS Transistors and ASIC

This paper presents the total dose radiation performance of 0. S^m SOI CMOS devices fabricated with full dose SIMOX technology. The radiation performance is characterized by threshold voltage shifts and leakage currents of transistors and standby currents of ASIC as functions of the total dose up to 500krad(Si) .The experimental results show that the worst case threshold voltage shifts of front channels are less than 320mV for pMOS transistors under off-gate radiation bias at lMrad(Si) and less than 120mV for nMOS transistors under on-gate radiation bias. No significant radiation-induced leakage current is observed in transistors to lMrad(Si). The standby currents of ASIC are less than the specification of 5μA over the total dose range of 500krad(Si).

Sensitivity of Total-Dose Radiation Hardness of SIMOX Buried Oxides to Doses of Nitrogen Implantation into Buried Oxides

In order to improve the total-dose radiation hardness of the buried oxides(BOX) in the structure of separa tion-by-implanted-oxygen(SIMOX) silicon-on-insulator(SOI), nitrogen ions are implanted into the buried oxides with two different doses,2 × 1015 and 3 × 1015 cm-2 , respectively. The experimental results show that the radiation hardness of the buried oxides is very sensitive to the doses of nitrogen implantation for a lower dose of irradiation with a Co-60 source. Despite the small difference between the doses of nitrogen implantation, the nitrogen-implanted 2 × 1015 cm-2 BOX has a much higher hardness than the control sample (i. e. the buried oxide without receiving nitrogen implantation) for a total-dose irradiation of 5 × 104rad(Si), whereas the nitrogen-implanted 3 × 1015 cm-2 BOX has a lower hardness than the control sample. However,this sensitivity of radiation hardness to the doses of nitrogen implantation reduces with the increasing total-dose of irradiation (from 5 × 104 to 5 × 105 rad (Si)). The radiation hardness of BOX is characterized by MOS high-frequency (HF) capacitance-voltage (C-V) technique after the top silicon layers are removed. In addition, the abnormal HF C-V curve of the metal-silicon-BOX-silicon(MSOS) structure is observed and explained.