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•Radon-contaminated groundwater is severe problem worldwide.•Hydrochemistry, microbial diversity, and health risk were assessed.•Health risk and pollution assessment using radon are ...sufficient in rainy season.•Radon, fluoride, and microbial data should be concurrently analyzed in dry season.•Seasonal effect is important for effective management of radon-contaminated zones.
Groundwater is an important human resource. Daejeon in South Korea faces severe water quality issues, including radon, uranium, and fluoride pollution, all of which pose health risks to humans. With climate change, threats to potable water, such as heavy rain and typhoons, have become common. Therefore, examining the seasonal effects on groundwater quality and resultant health risks is important for understanding the mechanisms of different hydroclimatological conditions to enable the implementation of sustainable management plans in radon-contaminated groundwater areas. However, this issue has not yet been studied. To bridge this gap, in this study, major ions and microbial community structures were employed and groundwater quality index (GWQI) were calculated with hazard index based on limits set by the World Health Organization (WHO) to investigate the hydrochemical characterization and to assess pollution levels. The results showed that the rainy season had distinct hydrochemical characteristics with high correlations between radon and fluoride, and most groundwater samples collected after the typhoon had characteristics similar to those collected during the dry season, owing to the flow path. Furthermore, the microbial diversity and hazard quotient (HQ) values of fluoride revealed that pollution worsened during the dry season. All of the calculated effective dose values of radon exceeded the threshold limit set by the WHO, despite the low GWQI. Infants and children were particularly susceptible to radon-contaminated groundwater. The statistical results of self-organizing map (SOM) suggested that radon analysis was sufficient for public health intervention in the rainy season; however, in the dry season, combined analyses of radon, fluoride, and microbial diversity played important roles in health risk assessment. Our study presents a comprehensive understanding of radon-contaminated groundwater characteristics under seasonal effects and can serve as a reference for other similar zones to provide significant insights into the effective management of radon contamination.
The resistive random-access memory (RRAM) with multi-level storage capability has been considered one of the most promising emerging devices to mimic synaptic behavior and accelerate analog ...computations. In this study, we investigated the reset-first bipolar resistive switching (RS) and multi-level characteristics of a LaNiO
thin film deposited using a reactive magnetron co-sputtering method. Polycrystalline phases of LaNiO
(LNO), without La
O
and NiO phases, were observed at similar fractions of Ni and La at a constant partial pressure of oxygen. The relative chemical proportions of Ni
and Ni
ions in LaNiO
indicated that it was an oxygen-deficient LaNiO
thin film, exhibiting RS behavior, compared to LNO without Ni
ions. The TiN/LaNiO
/Pt devices exhibited gradual resistance changes under various DC/AC voltage sweeps and consecutive pulse modes. The nonlinearity values of the conductance, measured via constant-pulse programming, were 0.15 for potentiation and 0.35 for depression, indicating the potential of the as-fabricated devices as analog computing devices. The LaNiO
-based device could reach multi-level states without an electroforming step and is a promising candidate for state-of-the-art RS memory and synaptic devices for neuromorphic computing.
The implementation of ultrahigh‐density cross‐point array structures has received considerable interest as emerging storage devices, and threshold switching devices are regarded to be promising as to ...the suppression of leakage current in cross‐point array structures. Threshold switching devices need to modulate the threshold voltage (Vth) depending on the various memory elements to achieve proper selector device in cross‐point array structures. However, only limited methods are available for controlling Vth. Therefore, the nitrogen (N) doping effects on trap states, density of localized states, and Vth of the amorphous Ga2Te3 (a‐Ga2Te3) selector devices are investigated herein. Furthermore, the electrical conduction behavior is fitted using a trap‐controlled space charge limited conduction mechanism with two transition voltages, i.e., the space charge limited voltage (VSCL) and trap‐filled limited voltage (VTFL). The optical bandgap energy and optical Urbach energy are affected by the N doping in a‐Ga2Te3. In addition, N doping in a‐Ga2Te3 increases the density of localized states. These effects increase both the transition voltages (VSCL and VTFL). Thus, doping a‐Ga2Te3 with N reduces Vth when the trap states are changed. Furthermore, N‐doped a‐Ga2Te3 selector devices exhibit highly reliable switching up to 109 cycles.
The threshold voltage of amorphous Ga2Te3 selector devices can be modulated by nitrogen doping with excellent stability over at least 109 switching cycles. Nitrogen‐induced changes of trap states reduce the threshold voltage and increase the transition voltages demarking the different regimes of current–voltage behavior in the high‐resistance state, as described by the trap‐controlled space charge limited conduction model.
Abstract Background Clinical observation conducted during the 3rd and 4th years of dental school is an important part of dental students’ clinical education. However, conventional clinical ...observation is associated with several problems, including the lack of opportunity for all students to assist during surgery. Virtual reality (VR) technologies and devices can be used to demonstrate clinical processes that dental students need to learn through clinical observation. This study aimed to evaluate the effectiveness of teaching dental students the surgical tooth extraction procedure through clinical observation using VR. Methods We recruited third- and fourth-year dental students and divided them into a VR clinical observation group (VR group) and a conventional clinical observation group (control group). The control group visited an outpatient clinic and observed an oral and maxillofacial specialist perform surgical tooth extraction, whereas the VR group watched a 360° video of surgical tooth extraction using a head-mounted display. After observation, both groups were surveyed regarding their satisfaction with the clinical observation and their understanding of the procedure. Results Understanding of the procedure and satisfaction with the observation were significantly higher in the VR group than in the control group ( p = 0.001 and p = 0.047, respectively). Compared with conventional clinical observation, VR clinical observation improved learning motivation and medical thinking and judgment skills; however, interaction between professors and students was lacking. Conclusions VR clinical observation using 360° videos might be an effective teaching method for students. However, to allow interaction between professors and students during clinical observations, using it along with conventional clinical observation is necessary.
Although ovarian cancer is the most lethal gynecologic malignancy in women, little is known about how the cancer initiates and metastasizes. In the last decade, new evidence has challenged the dogma ...that the ovary is the main source of this cancer. The fallopian tube has been proposed instead as the primary origin of high-grade serous ovarian cancer, the subtype causing 70% of ovarian cancer deaths. By conditionally deleting Dicer, an essential gene for microRNA synthesis, and Pten, a key negative regulator of the PI3K pathway, we show that high-grade serous carcinomas arise from the fallopian tube in mice. In these Dicer-Pten double-knockout mice, primary fallopian tube tumors spread to engulf the ovary and then aggressively metastasize throughout the abdominal cavity, causing ascites and killing 100% of the mice by 13 mo. Besides the clinical resemblance to human serous cancers, these fallopian tube cancers highly express genes that are known to be up-regulated in human serous ovarian cancers, also demonstrating molecular similarities. Although ovariectomized mice continue to develop high-grade serous cancers, removal of the fallopian tube at an early age prevents cancer formation—confirming the fallopian tube origin of the cancer. Intriguingly, the primary carcinomas are first observed in the stroma of the fallopian tube, suggesting that these epithelial cancers have a mesenchymal origin. Thus, this mouse model demonstrates a paradigm for the origin and initiation of high-grade serous ovarian carcinomas, the most common and deadliest ovarian cancer.
A major challenge in the clinical use of cytotoxic chemotherapeutics is maximizing efficacy in tumors while sparing normal tissue. Irinotecan is used for colorectal cancer treatment but the extent of ...its use is limited by toxic side effects. Liposomal delivery systems offer tools to modify pharmacokinetic and safety profiles of cytotoxic drugs. In this study, we defined parameters that maximize the antitumor activity of a nanoliposomal formulation of irinotecan (nal-IRI). In a mouse xenograft model of human colon carcinoma, nal-IRI dosing could achieve higher intratumoral levels of the prodrug irinotecan and its active metabolite SN-38 compared with free irinotecan. For example, nal-IRI administered at doses 5-fold lower than free irinotecan achieved similar intratumoral exposure of SN-38 but with superior antitumor activity. Tumor response and pharmacokinetic modeling identified the duration for which concentrations of SN-38 persisted above a critical intratumoral threshold of 120 nmol/L as determinant for antitumor activity. We identified tumor permeability and carboxylesterase activity needed for prodrug activation as critical factors in achieving longer duration of SN-38 in tumors. Simulations varying tumor permeability and carboxylesterase activity predicted a concave increase in tumor SN-38 duration, which was confirmed experimentally in 13 tumor xenograft models. Tumors in which higher SN-38 duration was achieved displayed more robust growth inhibition compared with tumors with lower SN-38 duration, confirming the importance of this factor in drug response. Overall, our work shows how liposomal encapsulation of irinotecan can safely improve its antitumor activity in preclinical models by enhancing accumulation of its active metabolite within the tumor microenvironment.
Abstract
This study aimed to investigate the preventive effect of teriparatide (TPD) administration on medication-related osteonecrosis of the jaw (MRONJ) before tooth extraction due to periodontal ...lesions in bilaterally ovariectomized female rats treated with zoledronic acid. Thirty skeletally mature Sprague–Dawley rats were randomly divided into three groups: control (CONT, n = 10), zoledronic acid (ZA, n = 10), and zoledronic acid and teriparatide (ZA-TPD, n = 10). The rats were sacrificed 8 weeks after tooth extraction. Micro-computed tomography analysis of the tibia showed that bone mineral density was highest in the CONT, followed by that in the ZA and ZA-TPD groups (CONT/ZA,
p
= 0.009; CONT/ZA-TPD,
p
< 0.001; ZA/ZA-TPD,
p
< 0.001). In the trabecular bone analysis of the extraction site, significant differences in specific bone surface (CONT/ZA,
p
= 0.010; CONT/ZA-TPD,
p
= 0.007; ZA/ZA-TPD,
p
= 0.002) and trabecular thickness (CONT/ZA-TPD,
p
= 0.002; ZA/ZA-TPD,
p
= 0.002) were observed. Histological analyses of the extraction sites revealed characteristic MRONJ lesions in the ZA group. Osteonecrosis, inflammatory cells, and sequestrum were less frequently observed in the ZA-TPD group than in the ZA group. In conclusion, TPD administration before tooth extraction helped reduce the occurrence of MRONJ in rats treated with zoledronic acid, confirming its preventative effects.
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This paper reports the negative effect of the cracked gas diffusion layer (GDL) on the performance of polymer electrolyte membrane fuel cells (PEMFCs) under varying flow channel ...width. The polarization characteristics and the corresponding electrochemical impedance spectra of the PEMFCs with pristine GDLs and cracked GDLs were computed. The results showed that for PEMFCs with 1.0mm flow channels, the power density rates of reduction between the PEMFCs with pristine GDLs and those with cracked GDLs were 2.8% under the condition of oxygen and 6.6% under the condition of air. On the other hand, for the PEMFCs with 0.5mm flow channels, these values were 10.3% under the oxygen condition and 14.2% under the air condition. This implies that the thinner the flow channels, the more severely the cracked GDLs influence the PEMFC performance in terms of concentration loss. The EIS data indicated that, compared to the PEMFCs with 1.0mm flow channels, the cracks on GDLs had more impact on the PEMFCs with 0.5mm flow channels with regard to activation overvoltage.
Threshold switching in chalcogenides has attracted considerable attention because of their potential application to high-density and three-dimensional stackable cross-point array structures. However, ...despite their excellent threshold switching characteristics, the selectivity and endurance characteristics of such selectors should be improved for practical application. In this study, the effect of Ag on the threshold switching behavior of a Ga
2
Te
3
selector was investigated in terms of selectivity and endurance. The Ag-Ga
2
Te
3
selector exhibited a high selectivity of 10
8
with low off-state current of < 100 fA, steep turn-on slope of 0.19 mV/dec, and high endurance of 10
9
cycles. The transient response was verified to depend on the pulse input voltage and measurement temperature. Considering its excellent threshold switching characteristics, the Ag-Ga
2
Te
3
selector is a promising candidate for applications in cross-point array structures.
Artificial intelligence (AI) is limited to teeth and periodontal disease in the dental field, and is used for diagnosis assistance or data analysis, and there has been no research conducted in actual ...clinical situations. So, we created an environment similar to actual clinical practice and conducted research by selecting three of the soft tissue diseases (carotid artery calcification, lymph node calcification, and sialolith) that are difficult for general dentists to see. Therefore, in this study, the accuracy and reading time are evaluated using panoramic images and AI. A total of 20,000 panoramic images including three diseases were used to develop and train a fast R-CNN model. To compare the performance of the developed model, two oral and maxillofacial radiologists (OMRs) and two general dentists (GDs) read 352 images, excluding the panoramic images used in development for soft tissue calcification diagnosis. On the first visit, the observers read images without AI; on the second visit, the same observers used AI to read the same image. The diagnostic accuracy and specificity for soft tissue calcification of AI were high from 0.727 to 0.926 and from 0.171 to 1.000, whereas the sensitivity for lymph node calcification and sialolith were low at 0.250 and 0.188, respectively. The reading time of AI increased in the GD group (619 to 1049) and decreased in the OMR group (1347 to 1372). In addition, reading scores increased in both groups (GD from 11.4 to 39.8 and OMR from 3.4 to 10.8). Using AI, although the detection sensitivity of sialolith and lymph node calcification was lower than that of carotid artery calcification, the total reading time of the OMR specialists was reduced and the GDs reading accuracy was improved. The AI used in this study helped to improve the diagnostic accuracy of the GD group, who were not familiar with the soft tissue calcification diagnosis, but more data sets are needed to improve the detection performance of the two diseases with low sensitivity of AI.
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