The change from phosphorus-limitation to nitrogen-limitation by eutrophication of Lake Soyang.

Article信州大学理学部附属諏訪臨湖実験所報告 9: 111-120(1995)departmental bulletin pape

Long-term variations of water quality and phosphorus loading in Lake Andong, Korea

Tropic state parameters were measured in a reservoir (Lake Andong, Korea) from 1993 to 2000. Phosphorus loading from the watershed was estimated by measuring total phosphorus concentration in the main inflowing stream (the Nakdong River). Phosphrus discharge of the pen-type fish farms was estimated from the amount of fish feed supplied annually and the rate of phosphrus excretion per feed weight. Minimum transparency in summer was only about 2.0m in 1993 and 1994, but it decreased to about 1.2m in 1997 and 1998, and recovered to about 2.3m in 1999 and 2000. TP increased from 11～30 mgP/m³ in 1993 to 18～42 mgP/m³ in 1998, but recovered to 8～13mgP/m³ in 2000, whereas TN decreased slightly from1.81～2.96mgN/L in 1993 to 1.17～1.80mgN/L in 2000. TN/TP ratio decreased from 82～281 in 1993 to 21～143 in 1998, but again increased to 101～209 in 2000 due to the decrease of TP. The average chlorophyll a concentration in growing season was in the range of 4.8-16.2mg/m³ from 1993 to 1997, but it decreased to 3.7-5.2 mg/m³ after 1998. The major cause of the trophic state recovery is thought to be the removal of fish farms in April 1998.Article信州大学山地水環境教育研究センター研究報告 2: 131-134(2004)departmental bulletin pape

The limnological survey of a coastal lagoon in Korea: Lake Hwajinpo

Physicochemical parameters, plankton biomass, and sediment were surveyed from 1998 to 2000 on two months interval in a eutrophic costal lagoon (Lake Hwajinpo, Korea) segregated from the sea by a sand dune. Littoral zone is well developed and floating-leaved aquatic plants also thrive, A shallow sill divides the lake into two basins. It has permeation of seawater and chemoclines formed by salinity were observed at 1m demth all the year around. DO was often very low(＜1mgO₂/L) at hypolimnion. Temperature inversions were observed in November. Transparency was 0.2～1.7m. Nitrate and ammonium concentrations were very low (＜0.1mgN/L), even though TN was usually 2.0～3.5mgN/L. TN/TP was generally lower than the Redfield ratio. TSI was 63～74, COD, TP, and TN of sediment were 3.1～40.3mgO₂/g, 0.9～1.39mg/m³. Two basins showed different phytoplankton communities with Oscillatoria sp., Trachelomonas sp., Schiaochlarnys gekatinosa, and Anabaena spiroides dominant in South basin, and with Trachelomonas sp., Schroederia sp., Schizochlamys felatinosa, and Trachelomonas sp. dominant in the North basin. The seasonal succession of phytoplankton was very fast, possibly due to sudden changes in physical characteristics such as wind, turbidity, salinity and light, etc.Article信州大学山地水環境教育研究センター研究報告 2: 127-130(2004)departmental bulletin pape

Enhancing photoluminescence quantum efficiency of metal halide perovskites by examining luminescence-limiting factors

Metal halide perovskites (MHPs) show superior optoelectronic properties, which give them the great potential for use in next generation light-emitting diodes (LEDs). In particular, their narrow emission linewidths can achieve ultrahigh color purity. However, the reported luminescence efficiency (LE) values are not high enough to be commercialized in displays and solid-state lightings. Moreover, the operational stability of LEDs associated with the overshooting of luminance and the high relative standard deviation of reported external quantum efficiencies are still problematic. In this perspective, we review photophysical factors that limit the photoluminescence quantum efficiency of perovskite-based LEDs. These factors are categorized into (i) weak exciton binding, (ii) nonradiative recombinations, (iii) slow cooling of long-lived hot carriers, (iv) deep-level defects, and (v) interband transition rates. We then present various physicochemical methods to effectively overcome these luminescence-limiting factors. We finally suggest some useful research directions to further improve the LE of MHP emitters as core components in displays and solid-state lightings.

EUTROPHICATION OF THE MAJOR RESERVOIRS IN KOREA

Trophic state of several major reservoirs in Korea are reviewed. Most of large reservoirs are mesotrophic to eutrophic, suffering bluegreen algal blooms. Recently many reservoirs are being eutrophied at high rate mainly due to the increase of excretion by livestock in watershed and netcage-type fishfarms within the lake basins. The trophic state changes of Lake Soyang, from oligotrophy to eutrophy in recent 10 years, are presented as a case study of rapid eutrophication. Chlorophyll a concentration increased from ca. 3mg/m³ in early 1980s to 15 mg/m³ in 1989. The dominant phytoplankton species in summer are changed from Peridinium to Anabaena since 1986 and the standing crop of Anabaena has been increasing. Secchidisc depth decreased from 5 to 1m. TP increased from 7 to 20 mgP/m³. The rate of hypolimnetic oxygen deficit increased year to year from 0.028 mgO₂/cm²/day in 1986 to 0.094 in 1989. Fishfarms within the lake are the major phosphorus source in Lake Soyang exceeding the total phosphorus loading from the watershed. This high rate of eutrophication is expected to persist in next decade.Article信州大学理学部付属諏訪臨湖実験所報告 7: 21-29(1991)departmental bulletin pape

Highly-Sensitive Textile Pressure Sensors Enabled by Suspended-Type All Carbon Nanotube Fiber Transistor Architecture.

Among various wearable health-monitoring electronics, electronic textiles (e-textiles) have been considered as an appropriate alternative for a convenient self-diagnosis approach. However, for the realization of the wearable e-textiles capable of detecting subtle human physiological signals, the low-sensing performances still remain as a challenge. In this study, a fiber transistor-type ultra-sensitive pressure sensor (FTPS) with a new architecture that is thread-like suspended dry-spun carbon nanotube (CNT) fiber source (S)/drain (D) electrodes is proposed as the first proof of concept for the detection of very low-pressure stimuli. As a result, the pressure sensor shows an ultra-high sensitivity of ~3050 Pa-1 and a response/recovery time of 258/114 ms in the very low-pressure range of <300 Pa as the fiber transistor was operated in the linear region (VDS = -0.1 V). Also, it was observed that the pressure-sensing characteristics are highly dependent on the contact pressure between the top CNT fiber S/D electrodes and the single-walled carbon nanotubes (SWCNTs) channel layer due to the air-gap made by the suspended S/D electrode fibers on the channel layers of fiber transistors. Furthermore, due to their remarkable sensitivity in the low-pressure range, an acoustic wave that has a very tiny pressure could be detected using the FTPS

The predictive value of PD-L1 expression in response to anti-PD-1/PD-L1 therapy for biliary tract cancer: a systematic review and meta-analysis

BackgroundRecently, anti-programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) immunotherapy offers promising results for advanced biliary tract cancer (BTC). However, patients show highly heterogeneous responses to treatment, and predictive biomarkers are lacking. We performed a systematic review and meta-analysis to assess the potential of PD-L1 expression as a biomarker for treatment response and survival in patients with BTC undergoing anti-PD-1/PD-L1 therapy.MethodsWe conducted a comprehensive systematic literature search through June 2023, utilizing the PubMed, EMBASE, and Cochrane Library databases. The outcomes of interest included objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), and overall survival (OS) according to PD-L1 expression. Subgroup analyses and meta-regression were performed to identify possible sources of heterogeneity.ResultsA total of 30 studies was included in the final analysis. Pooled analysis showed no significant differences in ORR (odds ratio [OR], 1.56; 95% confidence intervals [CIs], 0.94-2.56) and DCR (OR, 1.84; 95% CIs, 0.88-3.82) between PD-L1 (+) and PD-L1 (-) patients. In contrast, survival analysis showed improved PFS (hazard ratio [HR], 0.54, 95% CIs, 0.41-0.71) and OS (HR, 0.58; 95% CI, 0.47-0.72) among PD-L1 (+) patients compared to PD-L1 (-) patients. Sensitivity analysis excluding retrospective studies showed no significant differences with the primary results. Furthermore, meta-regression demonstrated that drug target (PD-1 vs. PD-L1), presence of additional intervention (monotherapy vs. combination therapy), and PD-L1 cut-off level (1% vs. ≥5%) significantly affected the predictive value of PD-L1 expression.ConclusionPD-L1 expression might be a helpful biomarker for predicting PFS and OS in patients with BTC undergoing anti-PD-1/PD-L1 therapy. The predictive value of PD-L1 expression can be significantly influenced by diagnostic or treatment variables.Systematic review registrationhttps://www.crd.york.ac.uk/PROSPERO, identifier CRD42023434114

Proton-transfer-induced 3D/2D hybrid perovskites suppress ion migration and reduce luminance overshoot

Abstract: Perovskite light-emitting diodes (PeLEDs) based on three-dimensional (3D) polycrystalline perovskites suffer from ion migration, which causes overshoot of luminance over time during operation and reduces its operational lifetime. Here, we demonstrate 3D/2D hybrid PeLEDs with extremely reduced luminance overshoot and 21 times longer operational lifetime than 3D PeLEDs. The luminance overshoot ratio of 3D/2D hybrid PeLED is only 7.4% which is greatly lower than that of 3D PeLED (150.4%). The 3D/2D hybrid perovskite is obtained by adding a small amount of neutral benzylamine to methylammonium lead bromide, which induces a proton transfer from methylammonium to benzylamine and enables crystallization of 2D perovskite without destroying the 3D phase. Benzylammonium in the perovskite lattice suppresses formation of deep-trap states and ion migration, thereby enhances both operating stability and luminous efficiency based on its retardation effect in reorientation

The change from phosphorus-limitation to nitrogen-limitation by eutrophication of Lake Soyang.

Articleapplication/pdf信州大学理学部附属諏訪臨湖実験所報告 9: 111-120(1995)departmental bulletin pape