Impact of floating gate dry etching on erase characteristics in NOR flash memory

We report the effects of plasma process-induced damage during floating gate (FG) dry-etching process on the erase characteristics of NOR flash cells. As compared to flash cells processed in a stable plasma condition, it is found that flash cells processed in the nonoptimized ambient show significantly degraded erase characteristics under a negative gate Fowler-Nordheim (FN) bias, exhibiting a fast-erasing bit in the distribution of erased bits. However, little differences are found in their tunneling characteristics under a positive gate biasing. The gate bias polarity dependence of FN tunneling indicates that positive charges are created near the poly-Si/SiO/sub 2/ interface during the FG dry-etching, prior to the backend processes such as metal- or via-etch.     

The First Inert and Photostable Encapsulated Lanthanide(III) Complexes Based on Dendritic 9,10‐Diphenylanthracene Ligands: Synthesis,Strong Near‐Infrared Emission Enhancement,and Photophysical Studies

A series of inert and photostable encapsulated lanthanide(III) complexes—based on dendritic anthracene ligands—is shown for the first time to exhibit strong near‐IR emission bands via efficient energy transfer from the excited states of the peripheral antenna to the Ln³⁺ ions (Er³⁺, Yb³⁺, and Nd³⁺). A significant decrease in the fluorescence of the anthracene ligand is accompanied by a strong increase in the near‐IR emission of the Ln³⁺ ions. The near‐IR emission intensities of Ln³⁺ ions in the encapsulated Ln³⁺–dendrimer complexes are dramatically enhanced on increasing the generation number (n) of dendrons, owing to site‐isolation and light‐harvesting effects. Furthermore, a first attempt is made to distinguish between the site‐isolation and light‐harvesting effects in the present complexes. Photophysical studies indicate the sensitization of Ln³⁺ luminescence by energy transfer through the excited singlet state of the anthracene ligands, and the energy‐transfer efficiency between the dendritic anthracene ligands and the Ln³⁺ ion is evaluated to be in the range of 90 to 97 %. Their energy‐transfer efficiency is in good agreement with the result that the biexponential decays contain a radiative decay of anthracene units (< ca. 10 %) and an energy‐transfer component (> ca. 90 %) from the excited state of anthracene ligands to the Ln³⁺ ions. Time‐resolved luminescence spectra show monoexponential decays with a lifetime of 2 μs for the Er³⁺ ion 11 μs for the Yb³⁺ ion and 0.7 μs for the Nd³⁺ ion in thin films, and calculated intrinsic quantum yields of the Ln³⁺ ions are in the range of ca. 0.025 to 0.55 %.     

Selective catalytic reduction by urea in a fluidized‐bed reactor

The selective catalytic reduction (SCR) of NO_x by urea as a reducing agent was carried out over fresh and sulfated CuO/γ‐Al₂O₃ catalysts in a fluidized‐bed reactor. The optimum temperature ranges for NO reduction on the fresh and sulfated CuO/γ‐Al₂O₃ catalysts were 300–350 °C and 400–450 °C, respectively. NO reduction with the sulfated CuO/γ‐Al₂O₃ catalyst was somewhat higher than that with the fresh CuO/γ‐Al₂O₃ catalyst. N₂O formation increased with increasing reaction temperature. Ammonia (NH₃) slip increased with increasing gas velocity and decreased with increasing reaction temperature. Copyright © 2003 Society of Chemical Industry     

Reappraisal of eight representative carcinogenic and non-carcinogenic compounds in a new medium-term rat liver bioassay using D-galactosamine

Tuberculosis incidence and mortality rates are rising steeply, reflecting economic hardship and the deterioration of the health infrastructure. The human and technical resources needed to reverse this trend are on hand, but cannot be used effectively without an adequate financial input. The cost of controlling tuberculosis now is modest compared with the cost of allowing it to increase.     

Initial and follow-up brain MRI findings and correlation with the clinical course in Wilson's disease

We performed pretreatment brain MRIs in 25 patients with neurologically symptomatic Wilson's disease (WD) and clinical and MRI follow-up in 16 of them. All 25 pretreatment MRIs revealed abnormalities, with abnormal high-signal intensity (HSI) in bilateral thalami being the most common (92%). HSI lesions in the brainstem (84%) and the basal ganglia (72%) were also common. Brain atrophy was present in 88% of the 25 patients. In the follow-up period of 5 to 24 months, during which the patients were treated with D-penicillamine, both HSI lesions and neurologic symptoms improved in 88% of the 16 patients, but the brain atrophy did not change.     

Development of microbial genome-probing microarrays using digital multiple displacement amplification of uncultivated microbial single cells

A crucial problem in the use of previously developed genome-probing microarrays (GPM) has been the inability to use uncultivated bacterial genomes to take advantage of the high sensitivity and specificity of GPM in microbial detection and monitoring. We show here a method, digital multiple displacement amplification (MDA), to amplify and analyze various genomes obtained from single uncultivated bacterial cells. We used 15 genomes from key microbes involved in dichloromethane (DCM)-dechlorinating enrichment as microarray probes to uncover the bacterial population dynamics of samples without PCR amplification. Genomic DNA amplified from single cells originating from uncultured bacteria with 80.3-99.4% similarity to 16S rRNA genes of cultivated bacteria. The digital MDA-GPM method successfully monitored the dynamics of DCM-dechlorinating communities from different phases of enrichment status. Without a priori knowledge of microbial diversity, the digital MDA-GPM method could be designed to monitor most microbial populations in a given environmental sample.     

Effects of formaldehyde/urea mole ratio and melamine content on the hydrolytic stability of cured urea-melamine-formaldehyde resin

The influence of formaldehyde/urea (F/U) mole ratio and melamine content on the hydrolytic stability of urea-melamine-formaldehyde (UMF) resin was investigated. The hydrolytic stability of cured UMF resin was determined by measuring the mass loss and the liberated formaldehyde concentration after acid hydrolysis. A higher F/U mole ratio and greater melamine content of UMF resins resulted in lower hydrolytic stability. These results indicated that higher F/U mole ratio and greater melamine content resulted in more branched network structure, which subsequently increases the susceptibility of cured UMF resin toward acid hydrolysis.