WATER PLANT SURVEY IN BOGOR, WEST JAVA, INDONESIA

A comparative survey of aquatic plants of eight ponds in and around Bogor, West Java, Indonesia, was preliminarily done to document the present status of aquatic flora in the locality. A total of 12 taxa were recorded, and most frequently encountered taxa were Eichhornia crassipes and Salvinia molesta. Number of taxa per pond ranged from one to eight and mean number was 4.9. Results of some water measurements and DCA application are also reported.Article信州大学理学部附属諏訪臨湖実験所報告 12: 19-23(2000)departmental bulletin pape

Distributions of biogeochemical parameters in the pool and interstitial waters in sand bar system of the Kizu River

Distributions of biogeochemical parameters in temporary pools (TAMARI), riparian side arm of river (WANDO) and interstitial waters were investigated in the sand bars along the lower reaches of the Kizu River. Dissloved inorganic nitrogen (DIN) and phosphate (DIP) concentrations in TAMARI and WANDO waters varied greatly compared with those in river waters. Low concentrations of DIN and DIP were often observed simultaneously in TAMARI waters. The DIN concentrations of most intersitial waters were similar or high in comparison to those of river waters. Low concentrations of DIN and DIP were often observed separately in intersitial waters. Concentrations of biogeochemical constituents clearly varied greatly in the waters of sand bar systems, and the relationships between each biogeochemical constituents were different between surface water (TAMARI and WANDO) and subsurface (intersitial) waters of the Kizu River.Article信州大学山地水環境教育研究センター研究報告 2: 63-67(2004)departmental bulletin pape

Mechanism of dynamic bias temperature instability in p- and nMOSFETs: The effect of pulse waveform

The waveform effect on dynamic bias temperature instability (BTI) is systematically studied for both p- and nMOSFETs with ultrathin SiON gate dielectrics by using a modified direct-current current-voltage method to monitor the stress-induced interface trap density. Interface traps are generated at the inversion gate bias (negative for pMOSFETs and positive for nMOSFETs) and are partially recovered at the zero or accumulation gate bias. Devices under high-frequency bipolar stress exhibit a significant frequency-dependent degradation enhancement. Approximate analytical expressions of the interface trap generation for devices under the static, unipolar, or bipolar stress are derived in the framework of conventional reaction-diffusion (R-D) model and with an assumption that additional interface traps (N*it) are generated in each cycle of the dynamic stress. The additional interface trap generation is proposed to originate from the transient trapped carriers in the states at and/or near the SiO2/Si interface upon the gate voltage reversal from the accumulation bias to the inversion bias quickly, which may accelerate dissociation of Si-H bonds at the beginning of the stressing phase in each cycle. Hence, N*it depends on the interface-state density, the voltage at the relaxation (i.e., accumulation) bias, and the transition time of the stress waveform (the fall time for pMOSFETs and the rise time for nMOSFETs). The observed dynamic BTI behaviors can be perfectly explained by this modified R-D model

Pulse waveform dependence on AC bias temperature instability in pMOSFETs

In this letter, the waveform effects on the degradation enhancement of pMOSFETs under high-frequency (≥ 10[4] Hz) bipolar-pulsed bias-temperature (BT) stresses were systematically studied. The enhancement was found to be mainly governed by the fall time (tF) of the pulse waveform, namely, the transition time of the silicon surface potential from strong accumulation to strong inversion, rather than the pulse rise time (tR) and the pulse duty factor (D). The enhancement decreases significantly with tF increasing, and is almost eliminated when tF is larger than ∼60 ns. This new finding is consistent with our newly proposed assumption that the recombination of free holes and trapped electrons at the SiO2/Si interface and/or near-interface states can enhance the interface trap generation

Interface trap generation induced by charge pumping current under dynamic oxide field stresses

Stress-induced interface trap generation (ΔNit) in the mid-channel region of standard n-channel MOSFETs with ultrathin plasma-nitrided SiO2 films (2.34 and 3.48 nm) were systematically studied under static and dynamic (both bipolar and unipolar) oxide field stresses over a wide frequency range from 1 to 10[7] Hz using a direct-current current-voltage measurement. At the bipolar stresses, ΔNit increases with the stress frequency significantly when the frequency is larger than ∼104 Hz while it saturates or decreases at the frequency larger than ∼107 Hz. The frequency dependence of the ΔNit enhancement can be attributed to a charge pumping current during the dynamic stress. Nitrogen incorporation increases not only ΔNit, but also the frequency dependence

Enhancement of BTI degradation in pMOSFETs under high-frequency bipolar gate bias

Negative bias temperature (NBT) instability of p-MOSFETs with ultrathin SiON gate dielectric has been investigated under various gate bias configurations. The NBT-induced interface trap density (ΔNit) under unipolar bias is essentially lower than that under static bias, and is almost independent of the stress frequency up to 10 MHz. On the contrary, ΔNit under bipolar pulsed bias of frequency larger than about 10 kHz is significantly enhanced and exhibits a strong frequency dependence, which has faster generation rate and smaller activation energy as compared to other stress configurations. The degradation enhancement is attributed to the energy to be contributed by the recombination of trapped electrons and free holes upon the silicon surface potential reversal from accumulation to inversion

Atomic layer-deposited Si-nitride/SiO2 stack gate dielectrics for future high-speed DRAM with enhanced reliability

Atomic layer-deposited (ALD) Si-nitride/SiO"2 stack gate dielectrics were applied to high-performance transistors for future scaled DRAMs. The stack gate dielectrics of the peripheral pMOS transistors excellently suppress boron penetration. ALD stack gate dielectrics exhibit only slightly worse negative-bias temperature instability (NBTI) characteristics than pure gate oxide. Enhanced reliability in NBTI was achieved compared with that of plasma-nitrided gate SiO"2. Memory-cell (MC) nMOS transistors with ALD stack gate dielectrics show slightly smaller junction leakage than those with plasma-nitrided gate SiO"2 in a high-drain-voltage region, and have identical junction leakage characteristics to transistors with pure gate oxide. MCs having transistors with ALD stack gate dielectrics and those with pure gate oxide have the identical retention-time distribution. Taking the identical hole mobility for the transistors with ALD stack gate dielectrics to that for the transistors with pure gate oxide both before and after hot carrier injection (previously reported) into account, the ALD stack dielectrics are a promising candidate for the gate dielectrics of future high-speed, reliable DRAMs

Functional tooth restoration by next-generation bio-hybrid implant as a bio-hybrid artificial organ replacement therapy

Bio-hybrid artificial organs are an attractive concept to restore organ function through precise biological cooperation with surrounding tissues in vivo. However, in bio-hybrid artificial organs, an artificial organ with fibrous connective tissues, including muscles, tendons and ligaments, has not been developed. Here, we have enveloped with embryonic dental follicle tissue around a HA-coated dental implant, and transplanted into the lower first molar region of a murine tooth-loss model. We successfully developed a novel fibrous connected tooth implant using a HA-coated dental implant and dental follicle stem cells as a bio-hybrid organ. This bio-hybrid implant restored physiological functions, including bone remodelling, regeneration of severe bone-defect and responsiveness to noxious stimuli, through regeneration with periodontal tissues, such as periodontal ligament and cementum. Thus, this study represents the potential for a next-generation bio-hybrid implant for tooth loss as a future bio-hybrid artificial organ replacement therapy

Practical whole-tooth restoration utilizing autologous bioengineered tooth germ transplantation in a postnatal canine model

Whole-organ regeneration has great potential for the replacement of dysfunctional organs through the reconstruction of a fully functional bioengineered organ using three-dimensional cell manipulation in vitro. Recently, many basic studies of whole-tooth replacement using three-dimensional cell manipulation have been conducted in a mouse model. Further evidence of the practical application to human medicine is required to demonstrate tooth restoration by reconstructing bioengineered tooth germ using a postnatal large-animal model. Herein, we demonstrate functional tooth restoration through the autologous transplantation of bioengineered tooth germ in a postnatal canine model. The bioengineered tooth, which was reconstructed using permanent tooth germ cells, erupted into the jawbone after autologous transplantation and achieved physiological function equivalent to that of a natural tooth. This study represents a substantial advancement in whole-organ replacement therapy through the transplantation of bioengineered organ germ as a practical model for future clinical regenerative medicine

Functional tooth number and mortality

Aim: Previous studies on the association between intraoral conditions and mortality in community-dwelling older individuals reported that fewer present teeth (PT) are significant risk factors for mortality. However, how the number of PT relative to the number of functional teeth (FT), including both present and rehabilitated teeth, influences mortality has not been investigated fully. This study examined the impact of the number of FT on mortality among community-dwelling Japanese older adults. Methods: This study was a retrospective, observational and population-based follow-up study, which examined 1188 older individuals who participated in an annual geriatric health examination from 2009 to 2015. The average follow-up period was 1697.0 ± 774.5 days. The primary outcome was all-cause mortality at follow-up. The numbers of PT and FT of each participant were counted during an oral examination. In addition, demographics, clinical variables, blood nutrient markers, physical functions and perceived masticatory function were measured. Results: Kaplan–Meier analysis, followed by a log-rank test, revealed that fewer PT (P < 0.001) and FT (P = 0.002) were significantly associated with a reduced survival rate. Cox's proportional hazard analysis indicated that the number of FT, but not the number of PT, was a significant independent mortality risk factor after adjusting for demographics, clinical variables, nutrient markers and physical functioning (P = 0.036, hazard ratio: 2.089). Conclusions: Current results suggest that the number of FT more strongly predicts all-cause mortality than the number of PT among community-dwelling older adults. Further studies are necessary to consider the confounding of socioeconomic status and disability status