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1.
Brain Tumor Res Treat ; 12(3): 172-180, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-39109618

RESUMEN

BACKGROUND: Modern neurosurgery has undergone significant evolution to include minimally invasive procedures, with the supraorbital approach (SOA) being a prime example. In this study, we aim to explore the surgical techniques and outcomes of this approach in the surgical treatment of frontal lobe, anterior skull base, and parasellar lesions. METHODS: This study included 33 patients aged 36-83 years who underwent surgery using the SOA for lesions in the inferior frontal lobe, anterior skull base, and parasellar area between 2015 and 2024. There were 25 cases of meningioma, 2 cases of brain abscess, 2 cases of glioma, and one case each of craniopharyngioma, hemangioma, metastasis, and Rathke's cleft cyst. The medical data and follow-up results were retrospectively analyzed. RESULTS: The mean size of lesion was 3.38±3.05 cm. The mean follow-up period was 48.8 months. Gross total resection was achieved in 25 patients (75.8%). There were no perioperative deaths, cases of cerebrospinal fluid rhinorrhea, or infections. Two cases of morbidity were reported as complications: one case of delayed intracerebral hemorrhage and one case of infarction due to vascular injury. All patients exhibited satisfactory cosmetic results. CONCLUSION: In comparison to the conventional pterional approach, the SOA represents a safe and effective keyhole method for the removal of both extra-axial and intra-axial skull base tumors. This is particularly beneficial for lesions in the orbitofrontal region and parasellar area, as it allows for minimal disruption of normal brain parenchyma. Moreover, the SOA promotes a swift recovery and short hospital stay. Additionally, the SOA yields superior cosmetic results, including the prevention of temporalis muscle atrophy.

2.
Heliyon ; 10(5): e27463, 2024 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-38495187

RESUMEN

Obesity leads to the development of metabolic syndrome and comorbidities. Overweight and obesity continue to be a relentless global issue. Sipyimigwanjung-tang (SGT), a traditional herbal medication, was first mentioned in Dongui Sasang Shinpyun and has been used to treat edema, meteorism, and jaundice, which are common findings associated with obesity. The main physiological feature of obesity is expanded adipose tissue, which causes several impairments in liver metabolism. Therefore, this study aimed to investigate the anti-obesity effects of SGT in the epididymal white adipose tissue (eWAT) and livers of high-fat diet (HFD)-induced obese mice. SGT significantly blocked HFD-induced weight gain in C57BL/6N mice. In addition, SGT effectively reduced the increased weight and adipocyte size in eWAT of HFD-induced obese C57BL/6 N mice. Moreover, SGT significantly decreased the elevated gene expression of Peroxisome proliferator-activated receptor γ, CCAAT/enhancer-binding protein α, and Sterol regulatory element-binding protein 1 in the eWAT of HFD-induced obese mice. Furthermore, SGT significantly decreased lipid accumulation in the livers of HFD-induced obese mice and differentiated 3T3-L1 adipocytes. Hence, the present study provides substantial evidence that SGT has potential therapeutic effects on obesity.

3.
Sensors (Basel) ; 23(3)2023 Jan 26.
Artículo en Inglés | MEDLINE | ID: mdl-36772418

RESUMEN

The shoe upper hides the foot motion on the insole, so it has been challenging to measure the non-slip function of socks in a dynamic motor task. The study aimed to propose a method to estimate the non-slip function of socks in an acute maneuver. Participants performed a shuttle run task while wearing three types of socks with different frictional properties. The forces produced by foot movement on the upper during the task were measured by pressure sensors installed at the upper. A force platform was also used to measure the ground reaction force at the outsole and ground. Peak force and impulse values computed by using forces measured by the pressure sensors were significantly different between the sock conditions, while there were no such differences in those values computed by using ground reaction forces measured by a force platform. The results suggested that the non-slip function of socks could be quantified by measuring forces at the foot-upper interface. The method could be an affordable option to measure the non-slip function of socks with minimal effects from skin artifacts and shoe upper integrity.


Asunto(s)
Pie , Zapatos , Humanos , Fricción , Movimiento (Física) , Piel
4.
Sci Rep ; 12(1): 8816, 2022 05 25.
Artículo en Inglés | MEDLINE | ID: mdl-35614162

RESUMEN

This study aimed to demonstrate the effectiveness of urgent extracranial-to-intracranial bypass (EIB) in acute ischemic stroke (AIS) through quantitative analysis of computed tomography perfusion (CTP) results using RAPID software. We retrospectively analyzed 41 patients who underwent urgent EIB for AIS under strict operation criteria. The quantitative data from CTP images were reconstructed to analyze changes in pre- and postoperative perfusion status in terms of objective numerical values using RAPID software. Short- and long-term clinical outcomes, including complications and neurological status, were also analyzed. Postoperatively, the volume of time-to-max (Tmax) > 6 s decreased significantly; it continued to improve significantly until 6 months postoperatively (preoperative, 78 ml (median); immediate postoperative, 23 ml; postoperative 6 months, 7 ml; p = 0.000). Ischemic core-penumbra mismatch volumes were also significantly improved until 6 months postoperatively (preoperative, 72 ml (median); immediate postoperative, 23 ml; postoperative 6 months, 5 ml; p = 0.000). In addition, the patients' neurological condition improved significantly (p < 0.001). Only one patient (2.3%) showed progression of infarction. Urgent EIB using strict indications can be a feasible treatment for IAT-ineligible patients with AIS due to large vessel occlusion or stenosis.


Asunto(s)
Isquemia Encefálica , Accidente Cerebrovascular Isquémico , Accidente Cerebrovascular , Humanos , Isquemia Encefálica/complicaciones , Isquemia Encefálica/diagnóstico por imagen , Isquemia Encefálica/cirugía , Hemodinámica , Accidente Cerebrovascular Isquémico/diagnóstico por imagen , Accidente Cerebrovascular Isquémico/cirugía , Estudios Retrospectivos , Accidente Cerebrovascular/diagnóstico por imagen , Accidente Cerebrovascular/etiología , Accidente Cerebrovascular/cirugía
5.
Sensors (Basel) ; 22(4)2022 Feb 20.
Artículo en Inglés | MEDLINE | ID: mdl-35214555

RESUMEN

Classifying space targets from debris is critical for radar resource management as well as rapid response during the mid-course phase of space target flight. Due to advances in deep learning techniques, various approaches have been studied to classify space targets by using micro-Doppler signatures. Previous studies have only used micro-Doppler signatures such as spectrogram and cadence velocity diagram (CVD), but in this paper, we propose a method to generate micro-Doppler signatures taking into account the relative incident angle that a radar can obtain during the target tracking process. The AlexNet and ResNet-18 networks, which are representative convolutional neural network architectures, are transfer-learned using two types of datasets constructed using the proposed and conventional signatures to classify six classes of space targets and a debris-cone, rounded cone, cone with empennages, cylinder, curved plate, and square plate. Among the proposed signatures, the spectrogram had lower classification accuracy than the conventional spectrogram, but the classification accuracy increased from 88.97% to 92.11% for CVD. Furthermore, when recalculated not with six classes but simply with only two classes of precessing space targets and tumbling debris, the proposed spectrogram and CVD show the classification accuracy of over 99.82% for both AlexNet and ResNet-18. Specially, for two classes, CVD provided results with higher accuracy than the spectrogram.


Asunto(s)
Redes Neurales de la Computación , Vuelo Espacial , Placas Óseas , Radar , Ultrasonografía Doppler
6.
World Neurosurg ; 158: e689-e696, 2022 02.
Artículo en Inglés | MEDLINE | ID: mdl-34800734

RESUMEN

OBJECTIVE: The treatment of multiple intracranial aneurysms (MIAs) involves various modalities and sometimes requires staged operations. This study aimed to prove the efficacy and safety of one-stage multiple craniotomies (OSMC) for multiple cerebral aneurysms. METHODS: We retrospectively reviewed the medical records of the patients who underwent treatment for intracranial aneurysms between May 2003 and April 2020. The surgical results, complications, and lengths of hospital stay were compared between the patients who underwent OSMC and those who underwent multistage multiple craniotomies. RESULTS: The demographic characteristics of the OSMC and multistage multiple craniotomies groups (n = 82 and 43, respectively) were similar. There were no statistically significant differences between the 2 groups when the amount of blood transfused, complications, and surgical results were compared (P = n.s. for all); however, the operation time and hospitalization period (353.9 minutes vs. 490.3 minutes and 12.3 days vs. 21.8 days, respectively; P = 0.001 for both) were shorter in the OSMC group. The treatment cost (17,000 USD vs. 22,000 USD, P = 0.001) was lower in the OSMC group. CONCLUSIONS: OSMC for aneurysm clipping in patients with MIAs is a relatively safe and economical method. Furthermore, it has good clinical outcomes. This new surgical method is worthwhile in that it can be applied to patients who are afraid to undergo multiple surgeries, and we suggest that it is an efficient, low-cost option for the treatment of MIAs.


Asunto(s)
Aneurisma Intracraneal , Craneotomía/métodos , Humanos , Aneurisma Intracraneal/cirugía , Tiempo de Internación , Estudios Retrospectivos , Resultado del Tratamiento , Procedimientos Quirúrgicos Vasculares
7.
J Korean Neurosurg Soc ; 65(1): 13-21, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34763379

RESUMEN

OBJECTIVE: Nontraumatic subdural hematoma (SDH) is a common disease, and spinal cerebrospinal fluid (CSF) leakage is a possible etiology of unknown significance, which is commonly investigated by several invasive studies. This study demonstrates that heavily T2-weighted magnetic resonance myelography (HT2W-MRM) is a safe and clinically effective imaging modality for detecting CSF leakage in patients with nontraumatic SDH. METHODS: All patients who underwent HT2W-MRM for nontraumatic SDH workup at our institution were searched and enrolled in this study. Several parameters were measured and analyzed, including patient demographic data, initial modified Rankin Scale (mRS) score upon presentation, SDH bilaterality, hematoma thickness upon presentation, CSF leakage sites, treatment modalities, follow-up hematoma thickness, and follow-up mRS score. RESULTS: Forty patients were identified, of which 22 (55.0%) had CSF leakage at various spinal locations. Five patients (12.5%) showed no change in mRS score, whereas the remaining (87.5%) showed decreases in follow-up mRS scores. In terms of the overall hematoma thickness, four patients (10.0%) showed increased thickness, two (5.0%) showed no change, 32 (80.0%) showed decreased thickness, and two (5.0%) did not undergo follow-up imaging for hematoma thickness measurement. CONCLUSION: HT2W-MRM is not only safe but also clinically effective as a primary diagnostic imaging modality to investigate CSF leakage in patients with nontraumatic SDH. Moreover, this study suggests that CSF leakage is a common etiology for nontraumatic SDH, which warrants changes in the diagnosis and treatment strategies.

8.
ACS Appl Mater Interfaces ; 13(36): 43480-43488, 2021 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-34460224

RESUMEN

Two-dimensional (2D) materials have been considered key materials for the future logic devices due to the excellent electrostatic integrity originating from their ultrathin nature. However, the carrier polarity control of 2D material field-effect transistors (FETs) still remains a challenging issue, hindering the realization of complementary logic function in the 2D material platform. Here, we report a comprehensive study on the electrical characteristics of PdSe2 FETs with different metal contacts. It is found that the carrier polarity in PdSe2 FETs can be modulated simply by changing the metal contact due to the weak Fermi-level pinning in PdSe2. We demonstrate a complementary metal-oxide-semiconductor (CMOS) inverter using the same channel material PdSe2 for n- and p-MOSFETs but with different metal contacts, suggesting the possible realization of PdSe2-based CMOS logic circuits.

9.
Sensors (Basel) ; 21(13)2021 Jun 25.
Artículo en Inglés | MEDLINE | ID: mdl-34202331

RESUMEN

Radar target classification is an important task in the missile defense system. State-of-the-art studies using micro-doppler frequency have been conducted to classify the space object targets. However, existing studies rely highly on feature extraction methods. Therefore, the generalization performance of the classifier is limited and there is room for improvement. Recently, to improve the classification performance, the popular approaches are to build a convolutional neural network (CNN) architecture with the help of transfer learning and use the generative adversarial network (GAN) to increase the training datasets. However, these methods still have drawbacks. First, they use only one feature to train the network. Therefore, the existing methods cannot guarantee that the classifier learns more robust target characteristics. Second, it is difficult to obtain large amounts of data that accurately mimic real-world target features by performing data augmentation via GAN instead of simulation. To mitigate the above problem, we propose a transfer learning-based parallel network with the spectrogram and the cadence velocity diagram (CVD) as the inputs. In addition, we obtain an EM simulation-based dataset. The radar-received signal is simulated according to a variety of dynamics using the concept of shooting and bouncing rays with relative aspect angles rather than the scattering center reconstruction method. Our proposed model is evaluated on our generated dataset. The proposed method achieved about 0.01 to 0.39% higher accuracy than the pre-trained networks with a single input feature.


Asunto(s)
Aprendizaje Profundo , Simulación por Computador , Redes Neurales de la Computación , Radar
10.
Sensors (Basel) ; 21(2)2021 Jan 08.
Artículo en Inglés | MEDLINE | ID: mdl-33435553

RESUMEN

Typically, the actual volume of the residual limb changes over time. This causes the prosthesis to not fit, and then pain and skin disease. In this study, a prosthetic socket was developed to compensate for the volume change of the residual limb. Using an inflatable air bladder, the proposed socket monitors the pressure in the socket and keeps the pressure distribution uniform and constant while walking. The socket has three air bladders on anterior and posterior tibia areas, a latching type 3-way pneumatic valve and a portable control device. In the paper, the mechanical properties of the air bladder were investigated, and the electromagnetic analysis was performed to design the pneumatic valve. The controller is based on a hysteresis control algorithm with a closed loop, which keeps the pressure in the socket close to the initial set point over a long period of time. In experiments, the proposed prosthesis was tested through the gait simulator that can imitate a human's gait cycle. The active volume compensation of the socket was successfully verified during repetitive gait cycle using the weight loads of 50, 70, and 90 kg and the residual limb model with a variety of volumes. It was confirmed that the pressure of the residual limb recovered to the initial state through the active control. The pressure inside the socket had a steady state error of less than 0.75% even if the volume of the residual limb was changed from -7% to +7%.


Asunto(s)
Muñones de Amputación , Miembros Artificiales , Humanos , Extremidad Inferior , Diseño de Prótesis , Tibia
11.
ACS Appl Mater Interfaces ; 13(1): 1861-1871, 2021 Jan 13.
Artículo en Inglés | MEDLINE | ID: mdl-33393295

RESUMEN

Achieving a high-quality metal contact on two-dimensional (2D) semiconductors still remains a major challenge due to the strong Fermi level pinning and the absence of an effective doping method. Here, we demonstrate high performance "all-PtSe2" field-effect transistors (FETs) completely free from those issues, enabled by the vertical integration of a metallic thick PtSe2 source/drain onto the semiconducting ultrathin PtSe2 channel. Owing to its inherent thickness-dependent semiconductor-to-metal phase transition, the transferred metallic PtSe2 transforms the underlying semiconducting PtSe2 into metal at the junction. Therefore, a fully metallized source/drain and semiconducting channel could be realized within the same PtSe2 platform. The ultrathin PtSe2 FETs with PtSe2 vdW contact exhibits excellent gate tunability, superior mobility, and high ON current accompanied by one order lower contact resistance compared to conventional Ti/Au contact FETs. Our work provides a new device paradigm with a low resistance PtSe2 vdW contact which can overcome a fundamental bottleneck in 2D nanoelectronics.

12.
Biomed Res Int ; 2020: 8851010, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33313321

RESUMEN

The global obesity epidemic has nearly doubled since 1980, and this increasing prevalence is threatening public health. It has been reported that natural products could contain potential functional ingredients that may assist in preventing obesity. Bojungchiseub-tang (BJT), mentioned in the Donguibogam as an herbal medication for the treatment of edema, a symptom of obesity, consists of eleven medicinal herbs. However, the pharmacological activity of BJT has not been investigated. The present study was designed to investigate the putative effect of BJT on the adipogenesis of 3T3-L1 cells and the weight gain of high-fat diet (HFD-) fed C57BL/6 mice. Oil Red O staining was conducted to examine the amount of lipids in 3T3-L1 adipocytes. Male C57BL/6 mice were divided into three groups: standard diet group (control, CON), 45% HFD group (HFD), and HFD supplemented with 10% of BJT (BJT). The expression levels of genes and proteins related to adipogenesis in cells, WAT, and liver were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot, respectively. We found that BJT treatment significantly decreased the protein and mRNA levels of peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein α (C/EBPα), and sterol regulatory element-binding protein 1 (SREBP1) in a dose-dependent manner in differentiated 3T3-L1 cells. Similar to the results of the in vitro experiment, BJT suppressed HFD-induced weight gain in an obese mouse model. In addition, BJT effectively reduced the HFD-induced epididymal adipose tissue weight/body weight index. BJT also downregulated the mRNA levels of PPARγ, C/EBPα, and SREBP1 in the epididymal adipose and liver tissue of HFD-fed obese mice. These findings suggest that BJT induces weight loss by affecting adipogenic transcription factors.


Asunto(s)
Adipocitos/efectos de los fármacos , Medicamentos Herbarios Chinos/farmacología , Epidídimo/efectos de los fármacos , Obesidad/tratamiento farmacológico , Células 3T3-L1 , Adipogénesis/efectos de los fármacos , Animales , Peso Corporal , Proteínas Potenciadoras de Unión a CCAAT/metabolismo , Supervivencia Celular , Dieta Alta en Grasa , Epidídimo/metabolismo , Lípidos/química , Masculino , Ratones , Ratones Endogámicos C57BL , PPAR gamma/metabolismo , República de Corea , Proteína 1 de Unión a los Elementos Reguladores de Esteroles/metabolismo
13.
Nanoscale ; 12(27): 14636-14641, 2020 Jul 21.
Artículo en Inglés | MEDLINE | ID: mdl-32614014

RESUMEN

High contact resistance (Rc) limits the ultimate potential of two-dimensional (2-D) materials for future devices. To resolve the Rc problem, forming metallic 1T phase MoS2 locally in the semiconducting 2H phase MoS2 has been successfully demonstrated to use the 1T phase as source/drain electrodes in field effect transistors (FETs). However, the long-term stability of the 1T phase MoS2 still remains as an issue. Recently, an unusual thickness-modulated phase transition from semiconducting to metallic has been experimentally observed in 2-D material PtSe2. Metallic multilayer PtSe2 and semiconducting monolayer PtSe2 can be used as source/drain electrodes and channel, respectively, in FETs. Here, we present a theoretical study on the intrinsic lower limit of Rc in the metallic-semiconducting PtSe2 heterostructure through density functional theory (DFT) combined with non-equilibrium Green's function (NEGF). Compared with Rc in the 1T-2H MoS2 heterostructure, the multilayer-monolayer PtSe2 heterostructure can offer much lower Rc due to the better capability of providing more transmission modes.

14.
J Korean Neurosurg Soc ; 62(6): 649-660, 2019 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-31591999

RESUMEN

OBJECTIVE: To analyze the angiographic features and clinical course, including treatment outcomes and the natural course, of fusiform middle cerebral artery aneurysms (FMCAAs) according to their location, size, and configuration. METHODS: We reviewed the literature on adult cases of FMCAAs published from 1980 to 2018; from 25 papers, 112 FMCAA cases, for which the location, size, and configuration could be identified, were included in this study. Additionally, 33 FMCAA cases in our hospital were included, from which 16 were assigned to the observation group. Thus, a total of 145 adult FMCAA cases were included. We classified the FMCAAs according to their location (l-type 1, beginning from prebifurcation; l-type 2, beginning from bifurcation; l-type 3, beginning from postbifurcation), size (small, <10 mm; large, ≥10 mm; giant, ≥25 mm), and configuration (c-type 1, classic dissecting aneurysm; c-type 2, segmental ectasia; c-type 3, dolichoectatic dissecting aneurysm). RESULTS: The c-type 3 was more commonly diagnosed with ischemic symptoms (31.8%) than hemorrhage (13.6%), while 40.9% were found accidentally. In contrast, c-type 2 was more commonly diagnosed with hemorrhagic symptoms (14.9%) than ischemic symptoms (10.6%), and 72.3% were accidentally discovered. According to location, ischemic symptoms and hemorrhage were the most frequent symptoms in l-type 1 (28.6%) and l-type 3 (34.6%), respectively. Most of l-type 2 FMCAAs were found incidentally (68.4%). Based on the size of FMCAAs, only 11.1% of small aneurysms were found to be hemorrhagic, while 18.9% and 26.0% of large and giant aneurysms were hemorrhagic, respectively. Although four aneurysms of the 16 FMCAAs in the observation group increased in size and one aneurysm decreased in size during the observation period, no rupture was seen in any case and there were no significant predictors of aneurysm enlargement. Of 104 FMCAAs treated, 14 cases (13.5%) were aggravated than before surgery and all the aggravated cases were l-type 1. CONCLUSION: While ischemic symptoms occurred more frequently in l-type 1 and c-type 3, hemorrhagic rather than ischemic symptoms occurred more frequently in l-type 3 and c-type 2. In case of l-type 1 FMCAAs, more caution is required in determining the treatment due to the relatively high complication rate.

15.
Biomed Res Int ; 2019: 3101987, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31467880

RESUMEN

There has been a remarkable interest in finding lipid inhibitors from natural products to replace synthetic compounds, and a variety of oriental medicinal herbs are reported to have biological activity with regard to lipid inhibition. Buginawa (Bugi) is a novel combined formula that contains twelve medicinal herbs with potential for weight loss induction. We hypothesized that Bugi may have antiobesity effects in 3T3-L1 preadipocytes and in a high-fat diet- (HFD-) induced mouse model. In this study, 3T3-L1 cells were treated with varied concentrations of Bugi (62.5, 125, or 250 µg/mL). Bugi treatment inhibited adipocyte differentiation by suppressing adipogenic transcription genes, including peroxisome proliferator-activated receptor γ protein (PPARγ), CCAAT/enhancer-binding protein α (C/EBPα), sterol regulatory element-binding protein 1 (SREBP1), and CCAAT/enhancer-binding protein ß (C/EBPß). Mice were fed a normal diet or an HFD for 11 weeks, and Bugi was simultaneously administered at 50 or 100 mg/kg. Bugi administration significantly reduced body weight gain and white adipose tissue (WAT) weight and effectively inhibited lipid droplet accumulation in epididymal white adipose tissue (eWAT) and liver tissue. Further, Bugi treatment suppressed mRNA levels of PPARγ, C/EBPα, and SREBP1 in eWAT and liver tissue. Our findings demonstrate that Bugi could be an effective candidate for preventing obesity and related metabolic disorders.


Asunto(s)
Tejido Adiposo Blanco/efectos de los fármacos , Metabolismo de los Lípidos/genética , Obesidad/tratamiento farmacológico , Preparaciones de Plantas/farmacología , Plantas Medicinales , Células 3T3-L1 , Adipocitos/efectos de los fármacos , Adipogénesis/efectos de los fármacos , Tejido Adiposo Blanco/crecimiento & desarrollo , Animales , Peso Corporal/efectos de los fármacos , Peso Corporal/genética , Proteínas Potenciadoras de Unión a CCAAT/genética , Diferenciación Celular/efectos de los fármacos , Dieta Alta en Grasa/efectos adversos , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Metabolismo de los Lípidos/efectos de los fármacos , Ratones , Obesidad/metabolismo , Obesidad/patología , PPAR gamma/genética
16.
Sci Rep ; 9(1): 3988, 2019 Mar 08.
Artículo en Inglés | MEDLINE | ID: mdl-30850758

RESUMEN

Two-dimensional (2-D) materials such as MoS2 and phosphorene provide an ideal platform to realize extremely thin body metal-oxide-semiconductor field effect transistors (MOSFETs) which is highly immune to short channel effects in the ultra-scaled regime. Even with the excellent electrostatic integrity inherent in 2-D system, however, 2-D materials suffer from the lack of efficient doping method which is crucial in MOSFETs technology. Recently, an unusual phase transition from semiconductor to metal driven by the thickness modulation has been predicted in mono-elemental 2-D material arsenene. Utilizing this extraordinary property, we propose doping-free arsenene heterostructure MOSFETs based on the lateral multilayer (metallic source)/monolayer (semiconducting channel)/multilayer (metallic drain) arsenene heterostructure. Metallic multilayer arsenene in the source and drain can serve as electrodes without doping. We investigate the potential performance of arsenene heterostructure MOSFETs through atomistic simulations using density functional theory and nonequilibrium Green's function. The intrinsic upper limit of the on-state current in arsenene heterostructure MOSFETs is estimated by studying the effect of layer number in the source and drain. We comprehensively analyze the competitiveness of arsenene heterostructure MOSFETs through benchmarking with monolayer arsenene homostructure MOSFETs equipped with the highly degenerate doped source and drain, suggesting superior performance of heterostructure MOSFETs over homostructure MOSFETs.

17.
Micromachines (Basel) ; 10(1)2019 Jan 08.
Artículo en Inglés | MEDLINE | ID: mdl-30626047

RESUMEN

We developed an implantable electrocardiogram (ECG) monitoring system and demonstrated its performance through an in vivo test. In the system, the implantable device senses not only the ECG signal of the animal but also the voltage level of the secondary cell and temperature inside the implantable device, and users can check the transmitted information through a PC program or a mobile application. The adoption of wireless charging technology eliminates the use of a lead wire and repetitive surgery to replace the implantable device. The proposed wireless charging technology demonstrated experimentally a wireless power transfer efficiency of approximately 30%. To minimize the size of the implantable device, the antenna and coil were integrated into a size of 34 mm × 14 mm. Communication between the implantable device and the basestation can reach up to 2.4 m when the implantable device is inserted into a porcine skin sample.

18.
Tuberc Respir Dis (Seoul) ; 72(3): 293-301, 2012 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-23227069

RESUMEN

BACKGROUND: Ventilator-associated pneumonia (VAP) requires prompt and appropriate treatment. Since methicillin-resistant Staphylococcus aureus (MRSA) is a frequent pathogen in VAP, rapid identification of it, is pivotal. Our aim was to evaluate the utility of quantitative polymerase chain reaction (qPCR) as a useful method for etiologic diagnoses of MRSA pneumonia. METHODS: We performed qPCR for mecA, S. aureus-specific femA-SA, and S. epidermidis-specific femA-SE genes from bronchoalveolar lavage or bronchial washing samples obtained from clinically-suspected VAP. Molecular identification of MRSA was based on the presence of the mecA and femA-SA gene, with the absence of the femA-SE gene. To compensate for the experimental and clinical conditions, we spiked an internal control in the course of DNA extraction. We estimated number of colony-forming units per mL (CFU/mL) of MRSA samples through a standard curve of a serially-diluted reference MRSA strain. We compared the threshold cycle (Ct) value with the microbiologic results of MRSA. RESULTS: We obtained the mecA gene standard curve, which showed the detection limit of the mecA gene to be 100 fg, which corresponds to a copy number of 30. We chose cut-off Ct values of 27.94 (equivalent to 1×10(4) CFU/mL) and 21.78 (equivalent to 1×10(5) CFU/mL). The sensitivity and specificity of our assay were 88.9% and 88.9% respectively, when compared with quantitative cultures. CONCLUSION: Our results were valuable for diagnosing and identifying pathogens involved in VAP. We believe our modified qPCR is an appropriate tool for the rapid diagnosis of clinical pathogens regarding patients in the intensive care unit.

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