Influence of backsurface argon bombardment on SiO2-Si interface characteristics

A low-energy (550 eV) argon-ion beam was used to directly bombard the backsurface of polysilicon-gate metal-oxide-semiconductor (MOS) capacitors after the completion of all conventional processing steps. The interface characteristics of the MOS capacitors were investigated. The results show that, as the bombardment dose increases, the active dopant concentration near the oxide-semiconductor interface gets higher; maximum midgap energy increases; and interface-state density becomes lower. This simple technique is compatible with existing integrated-circuit processing, and can easily improve the interface characteristics, and therefore the electrical characteristics of MOS devices. © 1996 American Institute of Physics.published_or_final_versio

Delay Adaptation Method for Relay Assisted Optical Wireless Systems

In this paper, we investigate optical wireless repeaters as relay terminals between a transmitter and a user in an Infrared Optical Wireless Communication (IROWC) system. A delay adaptation method is introduced to solve the problem of irregular signal arrival time from different relay terminals. Three different relay terminal deployment scenarios were investigated in a typical two-phase relay IROWC system with the proposed delay adaptation method. The simulation results indicate that the proposed system has better impulse response compared to the conventional system and that the root-mean-square delay spread of the relay system with the delay adaptation method is on average 30% less than the conventional system

Effects of chemical composition on humidity sensitivity of Al/BaTiO3/Si structure

Argon-ion-beam sputtering technique has been applied to deposit barium titanate (BaTiO3) films on silicon wafers at room temperature under vacuum, and then Al/BaTiO3/Si structures were fabricated. Results show that the current and capacitance of these devices are sensitive to the change of relative humidity at room temperature, and saturation absorption (response) time as well as humidity sensitivity of the devices depend on the chemical composition of the BaTiO3 films. For higher annealing temperature and longer annealing time, the oxygen composition increases while fixed charge density decreases. These changes result in lower humidity sensitivity and longer response time.© 1995 American Institute of Physics.published_or_final_versio

A study of various oxide/silicon interfaces by Ar + backsurface bombardment

A low-energy (550 eV) argon beam is used to bombard the backsurfaces of 6 kinds of metal–oxide–semiconductor capacitors, and the resulting effects on their interface characteristics are then investigated. The gate oxide of these capacitors includes thermal oxide, trichloroethyene (TCE) oxide, NH3-nitrided oxide, reoxidized-nitrided oxide, rapid-thermal-nitrided oxide, and N2O-nitrided oxide. Measurements show that for bombardment times up to 45 min the interface-state density of all the devices, in general, decreases with increasing bombardment time/dose, and the midgap energy at the silicon surface tends to rise. Moreover, the bombardment is more effective in reducing acceptor-type than donor-type interface states. On the other hand, the change of fixed-charge density is more complex. For TCE, N2O-nitrided and reoxidized-nitrided oxides, fixed-charge density decreases initially with increasing bombardment time, but then increases, while the trend is reversed for the other gate oxides. A model with stress compensation and weak bond breaking is suggested to explain the results. ©1999 American Institute of Physics.published_or_final_versio

Diffusivity of the uncinate fasciculus in heroin users relates to their levels of anxiety

Heroin use is closely associated with emotional dysregulation, which may explain its high comorbidity with disorders such as anxiety and depression. However, the understanding of the neurobiological etiology of the association between heroin use and emotional dysregulation is limited. Previous studies have suggested an impact of heroin on diffusivity in white matter involving the emotional regulatory system, but the specificity of this finding remains to be determined. Therefore, this study investigated the association between heroin use and diffusivity of white matter tracts in heroin users and examined whether the tracts were associated with their elevated anxiety and depression levels. A sample of 26 right-handed male abstinent heroin users (25 to 42 years of age) and 32 matched healthy controls (19 to 55 years of age) was recruited for this study. Diffusion tensor imaging data were collected, and their levels of anxiety and depression were assessed using the Hospital Anxiety and Depression Scale. Our findings indicated that heroin users exhibited higher levels of anxiety and depression, but the heroin use-associated left uncinate fasciculus was only related to their anxiety level, suggesting that association between heroin and anxiety has an incremental organic basis but that for depression could be a threshold issue. This finding improves our understanding of heroin addiction and its comorbid affective disorder and facilitates future therapeutic development.published_or_final_versio

Oncogenic role of clusterin overexpression in multistage colorectal tumorigenesis and progression

Aim: To investigate the expression pattern of clusterin in colorectal adenoma-carcinoma-metastasis series, and to explore the potential role of clustelin in multistage colorectal tumorigenesis and progression. Methods: A colorectal carcinoma (CRC)-tissue microarray (TMA), which contained 85 advanced CRCs including 43 cases of Dukes B, 21 of Dukes C and 21 of Dukes D tumors, were used for assessing the expression of clusterin (clone 41D) and tumor cell apoptotic index (AI) by immunohistochemistry and TUNEL assay, respectively. Moreover the potential correlation of clusterin expression with the patient's clinical-pathological features were also examined. Results: The positive staining of clusterin in different colorectal tissues was primarily a cytoplasmic pattern. Cytoplasmic overexpression of clusterin was detected in none of the normal colorectal mucosa, 17% of the adenomas, 46% of the primary CRCs, and 57% of the CRC metastatic lesions. In addition, a significant positive correlation between overexpression of clusterin and advanced clinical (Dukes) stage was observed (P<0.01). Overexpression of cytoplasmic clusterin in CRCs was inversely correlated with tumor apoptotic index (P<0.01), indicating the anti-apoptotic function of cytoplasmic clusterin in CRCs. Conclusion: These data suggests that overexpression of cytoplasmic clusterin might be involved in the tumorigenesis and/or progression of CRCs. The anti-apoptotic function of cytoplasmic clusterin may be responsible, at least in part, for the development and biologically aggressive behavior of CRC. © 2005 The WJG Press and Elsevier Inc. All rights reserved.published_or_final_versio

Doping Fe-based diamond tool matrix composites with a rare-earth element

The paper presents the experiments on adding rare-earth element cerium to diamond matrix composites. Based on the doping of rare earth in metal powders including tungsten carbide, a small amount of nickel, iron entirely replacing cobalt in diamond matrix and the process route of rare earth doping is indicated. The performance of matrix composites with and without rare-earth elements has been assessed. The results obtained show that the flexural strength, the hardness, and the impact ductility of matrix composites with rare-earth elements have been improved. The flexural strength and the impact ductility increased correspondently by 10—62 % and about 5 %, as compared to composites free of rare-earth elements. Rare-earth diamond tool matrix composites where Co was replaced with Fe, which provides a good practical service performanc, and a low price, have been successfully studied, corresponding diamond bits and saw blades have been manufactured

Carbon sequestration via wood burial

To mitigate global climate change, a portfolio of strategies will be needed to keep the atmospheric CO2 concentration below a dangerous level. Here a carbon sequestration strategy is proposed in which certain dead or live trees are harvested via collection or selective cutting, then buried in trenches or stowed away in above-ground shelters. The largely anaerobic condition under a sufficiently thick layer of soil will prevent the decomposition of the buried wood. Because a large flux of CO2 is constantly being assimilated into the world's forests via photosynthesis, cutting off its return pathway to the atmosphere forms an effective carbon sink

The phylogenetically-related pattern recognition receptors EFR and XA21 recruit similar immune signaling components in monocots and dicots

During plant immunity, surface-localized pattern recognition receptors (PRRs) recognize pathogen-associated molecular patterns (PAMPs). The transfer of PRRs between plant species is a promising strategy for engineering broad-spectrum disease resistance. Thus, there is a great interest in understanding the mechanisms of PRR-mediated resistance across different plant species. Two well-characterized plant PRRs are the leucine-rich repeat receptor kinases (LRR-RKs) EFR and XA21 from Arabidopsis thaliana (Arabidopsis) and rice, respectively. Interestingly, despite being evolutionary distant, EFR and XA21 are phylogenetically closely related and are both members of the sub-family XII of LRR-RKs that contains numerous potential PRRs. Here, we compared the ability of these related PRRs to engage immune signaling across the monocots-dicots taxonomic divide. Using chimera between Arabidopsis EFR and rice XA21, we show that the kinase domain of the rice XA21 is functional in triggering elf18-induced signaling and quantitative immunity to the bacteria Pseudomonas syringae pv. tomato (Pto) DC3000 and Agrobacterium tumefaciens in Arabidopsis. Furthermore, the EFR:XA21 chimera associates dynamically in a ligand-dependent manner with known components of the EFR complex. Conversely, EFR associates with Arabidopsis orthologues of rice XA21-interacting proteins, which appear to be involved in EFR-mediated signaling and immunity in Arabidopsis. Our work indicates the overall functional conservation of immune components acting downstream of distinct LRR-RK-type PRRs between monocots and dicots