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1.
Nanoscale Adv ; 6(14): 3624-3631, 2024 Jul 09.
Article in English | MEDLINE | ID: mdl-38989517

ABSTRACT

Two-dimensional (2D) van der Waals (vdW) heterostructures are considered as promising candidates for realizing multifunctional applications, including photodetectors, field effect transistors and solar cells. In this work, we performed first-principles calculations to design a 2D vdW MoTe2/MoS2 heterostructure and investigate its electronic properties, contact types and the impact of an electric field and in-plane biaxial strain. We find that the MoTe2/MoS2 heterostructure is predicted to be structurally, thermally and mechanically stable. It is obvious that the weak vdW interactions are mainly dominated at the interface of the MoTe2/MoS2 heterostructure and thus it can be synthesized in recent experiments by the transfer method or chemical vapor deposition. The construction of the vdW MoTe2/MoS2 heterostructure forms a staggered type II band alignment, effectively separating the electrons and holes at the interface and thereby extending the carrier lifetime. Interestingly, the electronic properties and contact types of the type II vdW MoTe2/MoS2 heterostructure can be tailored under the application of external conditions, including an electric field and in-plane biaxial strain. The semiconductor-semimetal-metal transition and type II-type I conversion can be achieved in the vdW MoTe2/MoS2 heterostructure. Our findings underscore the potential of the vdW MoTe2/MoS2 heterostructure for the design and fabrication of multifunctional applications, including electronics and optoelectronics.

2.
Phys Chem Chem Phys ; 26(27): 18892-18897, 2024 Jul 10.
Article in English | MEDLINE | ID: mdl-38949400

ABSTRACT

In this study, using the tight-binding model and Green's function technique, we investigate potential electronic phase transitions in bilayer P6mmm borophene under the influence of external stimuli, including a perpendicular electric field, electron-hole coupling between sublayers (excitonic effects), and dopants. Our focus is on key electronic properties such as the band structure and density of states. Our findings reveal that the pristine lattice is metal with Dirac cones around the Fermi level, where their intersection forms a nodal line. The system undergoes transitions to a semiconducting state - elimination of nodal line - with a perpendicular electric field and a semimetallic state - transition from two Dirac cones to a single Dirac cone - with combined electric field and excitonic effects. Notably, with these, the system retains its massless Dirac-like bands characteristic at finite energy. However, introducing a dopant still leads to a metallic phase, but the Dirac-like bands become massive. Considering all these effects, the system ultimately reaches a semiconducting phase with massive Dirac-like bands. These results hold significance for optoelectronic applications.

3.
ACS Omega ; 9(25): 27065-27070, 2024 Jun 25.
Article in English | MEDLINE | ID: mdl-38947855

ABSTRACT

In this study, S-deficient MoS2 was prepared using proton irradiation and then applied as sensing materials for the detection of NO2 gas. First, bulk MoS2 was treated by ultrasonics to produce 2D nanosheets of MoS2, which were subsequently bombarded by a flux of high-energy protons, resulting in the appearance of structural defects throughout MoS2. The proton fluxes were adjusted to different densities of 1 × 1011, 1 × 1012, 1 × 1013, and 1 × 1014 ions/cm2. The effects of proton irradiation on the defects, also referred to as atomic vacancies, were systematically investigated using Raman measurements to locate the E1 2g and A1g modes and X-ray photoelectron spectroscopy to determine the binding energy of Mo 3d and S 2p orbitals. It was revealed that the density of proton irradiation greatly affects the degree of S atom vacancies in irradiated MoS2, while also enhancing the n-type semiconducting behaviors of MoS2. The vacancy-rich MoS2 was then demonstrated to exhibit a higher response to NO2 gas compared to that of nonirradiated MoS2, showing a 4-fold increase in response within a concentration range from 1 to 20 ppm. These results could pave the way for new approaches to fabricating sensing materials.

4.
RSC Adv ; 14(30): 21982-21990, 2024 Jul 05.
Article in English | MEDLINE | ID: mdl-38993506

ABSTRACT

In this article, an attempt is made to explore new materials for applications in piezoelectric and electronic devices. Based on density functional theory calculation, we construct three Janus ZrGeZ3H (Z = N, P, and As) monolayers and study their stability, piezoelectricity, Raman response, and carrier mobility. The results from phonon dispersion spectra, ab initio molecular dynamics simulation, and elastic coefficients confirm the structural, thermal, and mechanical stability of these proposed structures. The ZrGeZ3H monolayers are indirect band gap semiconductors with favourable band gap energy of 1.15 and 1.00 eV for the ZrGeP3H and ZrGeAs3H, respectively, from Heyd-Scuseria-Ernzerhof functional method. It is found that the Janus ZrGeZ3H monolayers possess both in-plane and out-of-plane piezoelectric coefficients, revealing that they are potential piezoelectric candidates. In addition, the carrier mobilities of electrons and holes along transport directions are anisotropic. Notably, the ZrGeP3H and ZrGeAs3H monolayers have high electron mobility of 3639.20 and 3408.37 cm2 V-1 s-1, respectively. Our findings suggest the potential application of the Janus ZrGeZ3H monolayers in the piezoelectric and electronic fields.

5.
RSC Adv ; 14(27): 19014-19028, 2024 Jun 12.
Article in English | MEDLINE | ID: mdl-38873553

ABSTRACT

Graphitic carbon nitride supported silver nanoparticles (AgNPs/g-C3N4) with 1%, 3%, and 5% AgNPs were successfully synthesized by an "ex situ" method with ultrasound of a mixture of AgNP solution and g-C3N4. The AgNP solution was prepared by chemical reduction with trisodium citrate, and g-C3N4 was synthesized from the urea precursor. The supported nanoparticles were characterized by X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption-desorption (BET), Fourier transformation infrared (FTIR) and Raman spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), photoluminescence spectroscopy (PL), electron paramagnetic resonance (EPR) and electrochemical impedance spectroscopy (EIS) Nyquist plots. The visible light-driven photocurrent measurement was performed by three on-off cycles of intermittent irradiation. The analyses show that AgNPs were evenly dispersed on g-C3N4, and have sizes ranging from 40 to 50 nm. The optical properties of the AgNPs/g-C3N4 material were significantly enhanced due to the plasmonic effect of AgNPs. The photocatalytic activity of catalysts was evaluated by 2,4-D degradation under visible light irradiation (λ > 420 nm). In the reaction conditions: pH 2.2; C o (2,4-D) 40 ppm; a m/v ratio of 0.5 g L-1, AgNPs/g-C3N4 materials exhibit superior photocatalytic activity compared to the pristine g-C3N4. The studies on the influence of free radicals and photogenerated holes, h+, show that ˙OH, O2˙-, and h+ play decisive roles in the photocatalytic activity of AgNPs/g-C3N4. The TOC result indicates the minimal toxicity of the by-products formed during the 2,4-D degradation. In addition, the AgNPs/g-C3N4 catalytic activity under direct sunlight irradiation was similar to that under artificial UV irradiation. Based on these results, a possible mechanism is proposed to explain the enhanced photocatalytic activity and stability of AgNPs/g-C3N4. Theoretical calculations on the interaction between 2,4-D and g-C3N4, Ag/g-C3N4 was also performed. The calculated results show that the adsorption of 2,4-D on Ag-modified g-C3N4 is significantly more effective compared to pristine g-C3N4.

7.
J Colloid Interface Sci ; 670: 12-27, 2024 Sep 15.
Article in English | MEDLINE | ID: mdl-38749379

ABSTRACT

A new catalyst has been developed that utilizes molybdenum oxide (MoO3)/nickel molybdenum oxide (NiMoO4) heterostructured nanorods coupled with Pt ultrafine nanoparticles for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) toward industrial-grade water splitting. This catalyst has been synthesized using a versatile approach and has shown to perform better than noble-metals catalysts, such as Pt/C and RuO2, at industrial-grade current level (≥1000 mA·cm-2). When used simultaneously as a cathode and anode, the proposed material yields 10 mA·cm-2 at a remarkably small cell voltage of 1.55 V and has shown extraordinary durability for over 50 h. Density functional theory (DFT) calculations have proved that the combination of MoO3 and NiMoO4 creates a metallic heterostructure with outstanding charge transfer ability. The DFT calculations have also shown that the excellent chemical coupling effect between the MoO3/NiMoO4 and Pt synergistically optimize the charge transfer capability and Gibbs free energies of intermediate species, leading to remarkably speeding up the reaction kinetics of water electrolysis.

8.
Biochem Biophys Res Commun ; 719: 150043, 2024 Jul 30.
Article in English | MEDLINE | ID: mdl-38735206

ABSTRACT

In this study, a simple green synthesis of vanadium pentoxide nanoparticles (VNPs) was prepared by the extract of Kaffir lime fruit (Citrus hystrix) as a green reducing and stabilizing agent, along with the investigation of calcination temperature was carried out at 450 and 550 °C. It was affirmed that, at higher temperature (550 °C), the VNPs possessed a high degree crystalline following the construction of (001) lattice diffraction within an increase in crystalline size from 47.12 to 53.51 nm, although the band gap of the materials at 450 °C was lower than that of the VNPs-550 (2.53 versus 2.66 eV, respectively). Besides, the materials were assessed for the potential bioactivities toward antibacterial, antifungal, DNA cleavage, anti-inflammatory, and hemolytic performances. As a result, the antibacterial activity, with minimal inhalation concentration (MIC) < 6.25 µg/mL for both strains, and fungicidal one of the materials depicted the dose-dependent effects. Once, both VNPs exhibited the noticeable efficacy of the DNA microbial damage, meanwhile, the outstanding anti-inflammatory agent was involved with the IC50 of 123.636 and 227.706 µg/mL, accounting for VNPs-450 and VNPs-550, respectively. Furthermore, this study also demonstrated the hemolytic potential of the VNPs materials. These consequences declare the prospects of the VNPs as the smart and alternative material from the green procedure in biomedicine.


Subject(s)
Anti-Bacterial Agents , Citrus , Fruit , Plant Extracts , Vanadium Compounds , Citrus/chemistry , Plant Extracts/chemistry , Plant Extracts/pharmacology , Vanadium Compounds/chemistry , Vanadium Compounds/pharmacology , Fruit/chemistry , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/chemical synthesis , Nanoparticles/chemistry , Microbial Sensitivity Tests , Anti-Inflammatory Agents/pharmacology , Anti-Inflammatory Agents/chemistry , Antifungal Agents/pharmacology , Antifungal Agents/chemistry , Antifungal Agents/chemical synthesis , Temperature , Hemolysis/drug effects , Green Chemistry Technology , Humans
9.
Microb Cell Fact ; 23(1): 115, 2024 Apr 20.
Article in English | MEDLINE | ID: mdl-38643109

ABSTRACT

BACKGROUND: The process of producing proteins in bacterial systems and secreting them through ATP-binding cassette (ABC) transporters is an area that has been actively researched and used due to its high protein production capacity and efficiency. However, some proteins are unable to pass through the ABC transporter after synthesis, a phenomenon we previously determined to be caused by an excessive positive charge in certain regions of their amino acid sequence. If such an excessive charge is removed, the secretion of any protein through ABC transporters becomes possible. RESULTS: In this study, we introduce 'linear charge density' as the criteria for possibility of protein secretion through ABC transporters and confirm that this criterion can be applied to various non-secretable proteins, such as SARS-CoV-2 spike proteins, botulinum toxin light chain, and human growth factors. Additionally, we develop a new algorithm, PySupercharge, that enables the secretion of proteins containing regions with high linear charge density. It selectively converts positively charged amino acids into negatively charged or neutral amino acids after linear charge density analysis to enable protein secretion through ABC transporters. CONCLUSIONS: PySupercharge, which also minimizes functional/structural stability loss of the pre-mutation proteins through the use of sequence conservation data, is currently being operated on an accessible web server. We verified the efficacy of PySupercharge-driven protein supercharging by secreting various previously non-secretable proteins commonly used in research, and so suggest this tool for use in future research requiring effective protein production.


Subject(s)
ATP-Binding Cassette Transporters , Amino Acids , Humans , ATP-Binding Cassette Transporters/metabolism , Amino Acids/metabolism , Bacterial Proteins/metabolism , Mutation , Amino Acid Sequence
10.
Int J Biol Macromol ; 268(Pt 2): 131760, 2024 May.
Article in English | MEDLINE | ID: mdl-38663693

ABSTRACT

In the adsorption process for wastewater treatment, the adsorbent plays an important role. A composite adsorptive material composed of graphitic carbon nitride and agar-derived porous carbon (CNPC) was fabricated from simple precursors (melamine, thiourea, and agar) and through a facile procedure with different melamine and thiourea ratios. Characterization of CNPC proved a successful formation of a porous structure consisting of mesopores and macropores, wherein CNPC holds distinctive electrochemical (lowered resistance and higher specific capacity) and photochemical properties (lowered bandgap to 2.33 eV) thanks to the combination of graphitic carbon nitride (CN) and agar-derived porous carbon (PC). Inheriting the immanent nature, CNPC was subjected to the adsorption of methylene blue (MB) dye in an aqueous solution. The highest adsorption capacity was 133 mg/g for CNPC-4 which was prepared using a melamine to thiourea ratio of 4:4 - equivalent to the removal rate of 53.2 % and following the pseudo-I-order reaction rate. The effect of pH points out that pH 7 and 9 were susceptible to maximum removal and pretreatment is not required while the optimal ratio of 7.5 mg of MB and 30 mg of material was also determined to yield the highest performance. Furthermore, the reusability of the material for three consecutive cycles was evaluated based on two methods pyrolysis at 200 °C and photocatalytic degradation by irradiation under visible light. In general, the photocatalytic regeneration pathway is more ample and efficient than pyrolysis in terms of energy efficiency (saving energy over 10 times) and adsorption capacity stability. As a whole, the construction of accessible regenerative and stable adsorbent could be a venturing step into the sustainable development spearhead for industries.


Subject(s)
Agar , Graphite , Methylene Blue , Water Pollutants, Chemical , Adsorption , Graphite/chemistry , Porosity , Water Pollutants, Chemical/chemistry , Water Pollutants, Chemical/isolation & purification , Methylene Blue/chemistry , Agar/chemistry , Water Purification/methods , Triazines/chemistry , Environmental Restoration and Remediation/methods , Carbon/chemistry , Wastewater/chemistry , Hydrogen-Ion Concentration , Nitrogen Compounds/chemistry , Kinetics , Thiourea/chemistry
11.
Phys Chem Chem Phys ; 26(12): 9657-9664, 2024 Mar 20.
Article in English | MEDLINE | ID: mdl-38469888

ABSTRACT

Two-dimensional (2D) metallic TaSe2 and semiconducting WSe2 materials have been successfully fabricated in experiments and are considered as promising contact and channel materials, respectively, for the design of next-generation electronic devices. Herein, we design a metal-semiconductor (M-S) heterostructure combining metallic TaSe2 and semiconducting WSe2 materials and investigate the atomic structure, electronic properties and controllable contact types of the combined TaSe2/WSe2 M-S heterostructure using first-principles calculations. Our results reveal that the TaSe2/WSe2 M-S heterostructure can adopt four different stable stacking configurations, all of which exhibit enhanced elastic constants compared to the constituent monolayers. Furthermore, the TaSe2/WSe2 M-S heterostructure exhibits p-type Schottky contact (SC) with Schottky barriers ranging from 0.36 to 0.49 eV, depending on the stacking configurations. The TaSe2/WSe2 M-S heterostructure can be considered as a promising M-S contact for next-generation electronic Schottky devices owing to its small tunneling resistivity of about 2.14 × 10-9 Ω cm2. More interestingly, the TaSe2/WSe2 M-S heterostructure exhibits tunable contact types and contact barriers under the application of an electric field. A negative electric field induces a transition from Schottky contact type to ohmic contact (OC) type. On the other hand, a positive electric field leads to a transformation from p-type SC to n-type SC. Our findings provide valuable insights into the practical applications of the TaSe2/WSe2 M-S heterostructure towards next-generation electronic devices.

12.
Nanoscale Adv ; 6(4): 1193-1201, 2024 Feb 13.
Article in English | MEDLINE | ID: mdl-38356616

ABSTRACT

The emergence of van der Waals (vdW) heterostructures, which consist of vertically stacked two-dimensional (2D) materials held together by weak vdW interactions, has introduced an innovative avenue for tailoring nanoelectronic devices. In this study, we have theoretically designed a metal/semiconductor heterostructure composed of NbS2 and Janus MoSSe, and conducted a thorough investigation of its electronic properties and the formation of contact barriers through first-principles calculations. The effects of stacking configurations and the influence of external electric fields in enhancing the tunability of the NbS2/Janus MoSSe heterostructure are also explored. Our findings demonstrate that the NbS2/MoSSe heterostructure is not only structurally and thermally stable but also exfoliable, making it a promising candidate for experimental realization. In its ground state, this heterostructure exhibits p-type Schottky contacts characterized by small Schottky barriers and low tunneling barrier resistance, showing its considerable potential for utilization in electronic devices. Additionally, our findings reveal that the electronic properties, contact barriers and contact types of the NbS2/MoSSe heterostructure can be tuned by applying electric fields. A negative electric field leads to a conversion from a p-type Schottky contact to an n-type Schottky contact, whereas a positive electric field gives rise to a transformation from a Schottky into an ohmic contact. These insights offer valuable theoretical guidance for the practical utilization of the NbS2/MoSSe heterostructure in the development of next-generation electronic and optoelectronic devices.

13.
RSC Adv ; 14(7): 4966-4974, 2024 Jan 31.
Article in English | MEDLINE | ID: mdl-38327810

ABSTRACT

The auxetic materials have exotic mechanical properties compared to conventional materials, such as higher indentation resistance, more superior sound absorption performance. Although the auxetic behavior has also been observed in two-dimensional (2D) nanomaterials, to date there has not been much research on auxetic materials in the vertical asymmetric Janus 2D layered structures. In this paper, we explore the mechanical, electronic, and transport characteristics of Janus Si2OX (X = S, Se, Te) monolayers by first-principle calculations. Except for the Si2OTe monolayer, both Si2OS and Si2OSe are found to be stable. Most importantly, both Si2OS and Si2OSe monolayers are predicted to be auxetic semiconductors with a large negative Poisson's ratio. The auxetic behavior is clearly observed in the Janus Si2OS monolayer with an extremely large negative Poisson's ratio of -0.234 in the x axis. At the equilibrium state, both Si2OS and Si2OSe materials exhibit indirect semiconducting characteristics and their band gaps can be easily altered by the mechanical strain. More interestingly, the indirect-direct bandgap phase transitions are observed in both Si2OS and Si2OSe monolayers when the biaxial strains are introduced. Further, the studied Janus structures also exhibit remarkably high electron mobility, particularly along the x direction. Our findings demonstrate that Si2OS and Si2OSe monolayers are new auxetic materials with asymmetric structures and show their great promise in electronic and nanomechanical applications.

14.
Sci Total Environ ; 912: 168985, 2024 Feb 20.
Article in English | MEDLINE | ID: mdl-38056666

ABSTRACT

Understanding the regular variations in water levels and identifying the potential drivers under the combined pressures of anthropogenic activities and climate change can offer valuable insights into riverine management. In this study, we analyzed long-term daily observational data, including water levels and water discharge, spanning from the ~1950s to 2021 at seven gauging stations within the Red River basin. We investigated the spatiotemporal variation in mean water levels using standard analytical tools, including the Mann-Kendall (MK) test, rating curves, and Empirical Orthogonal Function (EOF). Specifically, we observed a notable and substantial decline in water levels downstream of the major tributaries, including Da, Red, and Lo Rivers, as well as at their confluence, starting at the end of 2008. Notably, a strong correlation between water levels and discharge is found, highlighting the pivotal role of discharge in influencing water levels. Surprisingly, relationships between water levels and climatic factors such as rainfall and air temperature proved less influential. This suggests that water levels are predominantly shaped by discharge and anthropogenic activities, rather than climate change. The study emphasized the substantial impact of human-induced activities, particularly dam operation and sand mining, on downstream water levels in the Red River basin. An intriguing finding revealed that upstream dynamics, particularly at the Hoa Binh dam, led to significant water level increases with the same discharge, attributed to channel deposition and reservoir water storage. The research's novelty is the comprehensive evaluation of long-term water level trends and its elucidation of the combined effects of anthropogenic activities and climate change, offering valuable insights for riverine management and emphasizing the influence of anthropogenic factors, notably dam regulation and sand mining, in driving shifts in water levels.

15.
Phys Chem Chem Phys ; 26(3): 1917-1928, 2024 Jan 17.
Article in English | MEDLINE | ID: mdl-38115720

ABSTRACT

Reduction mechanisms between hydrazine and a multi-epoxide arrangement were investigated on a finite-sized graphene-oxide model with density functional theory. Three multistep reaction pathways were explored to examine different graphene-oxide (GO) deoxygenation scenarios. Epoxides sharing the same hexagonal ring show the typical one-by-one elimination of the oxygen functional groups through two protonation steps and the formation of cis-diazine and water. Nevertheless, the migration of one of the epoxy groups to an out-of-ring position has to precede the reduction. When a hexagonal ring separates two epoxy groups, forming a partially reduced surface with two hydroxyl groups is energetically favoured. This reduction product is so stable that it may remain on the surface after the termination of the reduction process. If further deoxygenation occurs, it can lead to surface fragmentation due to the ring opening of the remaining epoxides. The formation of nitrogen-containing functional groups at the edge of the graphene-oxide flake is also considered, and their surface presence is evaluated based on their thermodynamic stabilities.

16.
Langmuir ; 39(48): 17251-17260, 2023 Dec 05.
Article in English | MEDLINE | ID: mdl-37972320

ABSTRACT

Conducting heterostructures have emerged as a promising strategy to enhance physical properties and unlock the potential application of such materials. Herein, we conduct and investigate the electronic and transport properties of the BSe/Sc2CF2 heterostructure using first-principles calculations. The BSe/Sc2CF2 heterostructure is structurally and thermodynamically stable, indicating that it can be feasible for further experiments. The BSe/Sc2CF2 heterostructure exhibits a semiconducting behavior with an indirect band gap and possesses type-II band alignment. This unique alignment promotes efficient charge separation, making it highly promising for device applications, including solar cells and photodetectors. Furthermore, type-II band alignment in the BSe/Sc2CF2 heterostructure leads to a reduced band gap compared to the individual BSe and Sc2CF2 monolayers, leading to enhanced charge carrier mobility and light absorption. Additionally, the generation of the BSe/Sc2CF2 heterostructure enhances the transport properties of the BSe and Sc2CF2 monolayers. The electric fields and strains can modify the electronic properties, thus expanding the potential application possibilities. Both the electric fields and strains can tune the band gap and lead to the type-II to type-I conversion in the BSe/Sc2CF2 heterostructure. These findings shed light on the versatile nature of the BSe/Sc2CF2 heterostructure and its potential for advanced nanoelectronic and optoelectronic devices.

17.
Sensors (Basel) ; 23(21)2023 Oct 26.
Article in English | MEDLINE | ID: mdl-37960447

ABSTRACT

Artificial intelligence (AI) radar technology offers several advantages over other technologies, including low cost, privacy assurance, high accuracy, and environmental resilience. One challenge faced by AI radar technology is the high cost of equipment and the lack of radar datasets for deep-learning model training. Moreover, conventional radar signal processing methods have the obstacles of poor resolution or complex computation. Therefore, this paper discusses an innovative approach in the integration of radar technology and machine learning for effective surveillance systems that can surpass the aforementioned limitations. This approach is detailed into three steps: signal acquisition, signal processing, and feature-based classification. A hardware prototype of the signal acquisition circuitry was designed for a Continuous Wave (CW) K-24 GHz frequency band radar sensor. The collected radar motion data was categorized into non-human motion, human walking, and human walking without arm swing. Three signal processing techniques, namely short-time Fourier transform (STFT), mel spectrogram, and mel frequency cepstral coefficients (MFCCs), were employed. The latter two are typically used for audio processing, but in this study, they were proposed to obtain micro-Doppler spectrograms for all motion data. The obtained micro-Doppler spectrograms were then fed to a simplified 2D convolutional neural networks (CNNs) architecture for feature extraction and classification. Additionally, artificial neural networks (ANNs) and 1D CNN models were implemented for comparative analysis on various aspects. The experimental results demonstrated that the 2D CNN model trained on the MFCC feature outperformed the other two methods. The accuracy rate of the object classification models trained on micro-Doppler features was 97.93%, indicating the effectiveness of the proposed approach.


Subject(s)
Artificial Intelligence , Radar , Humans , Signal Processing, Computer-Assisted , Walking , Fourier Analysis
18.
Nanoscale Adv ; 5(23): 6705-6713, 2023 Nov 21.
Article in English | MEDLINE | ID: mdl-38024315

ABSTRACT

From the extending requirements for using innovative materials in advanced technologies, it is necessary to explore new materials for relevant applications. In this work, we design new two-dimensional (2D) Janus ZrSiSZ2 (Z = N, P, As) monolayers and investigate their crystal lattice and dynamic stability by using density functional theory investigations. The two stable structures of ZrSiSP2 and ZrSiSAs2 are then systematically examined for thermal, energetic, and mechanical stability, and electronic and transport properties. The calculation results demonstrate that both the ZrSiSP2 and ZrSiSAs2 monolayers have good thermal stability at room temperature and high energetic/mechanical stabilities for experimental synthesis. The studied structures are found to be in-direct semiconductors. Specifically, with moderate band-gap energies of 1.04 to 1.29 eV for visible light absorption, ZrSiSP2 and ZrSiSAs2 can be considered potential candidates for photovoltaic applications. The applied biaxial strains and external electric fields slightly change the band-gap energies of the monolayers. We also calculate the carrier mobilities for the transport properties based on the deformation potential method. Due to the lower effective masses, the carrier mobilities in the x direction are higher than those in the y direction. The carrier mobilities of the ZrSiSP2 and ZrSiSAs2 monolayers are anisotropic not only in transport directions but also for the electrons and holes. We believe that the results of our work may stimulate further studies to explore more new 2D Janus monolayers with novel properties of the MA2Z4 family materials.

19.
Contemp Oncol (Pozn) ; 27(2): 71-79, 2023.
Article in English | MEDLINE | ID: mdl-37794989

ABSTRACT

Introduction: This study aimed to evaluate the treatment outcomes of epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) therapy alone or in combination with locoregional brain therapy for advanced EGFR-mutant non-small cell lung cancer (NSCLC) patients with brain metastases. Material and methods: A retrospective study involving 72 advanced EGFR-mutant NSCLC patients with brain metastases at the Vietnam National Cancer Hospital were conducted. Patients were divided into 2 groups: EGFR-TKI (erlotinib) monotherapy and EGFR-TKI combined with locoregional therapy (γ knife surgery - GKS or whole-brain radiation therapy). Evaluation criteria included clinical and laboratory characteristics, central nervous system (CNS) progression time, progression-free survival (PFS), overall survival (OS), T790M mutation rate, and adverse events. Results: Epidermal growth factor receptor tyrosine kinase inhibitor monotherapy patients had better performance status (PS), fewer CNS symptoms, and significantly fewer brain metastases (p < 0.05). Median PFS and OS were 11 and 25 months, respectively, in both groups. Patients with PS 0-1 had longer median PFS (15 months) than those with PS 2 (7 months) (p = 0.039). Exon 19 deletion patients in both groups had longer median OS (26 months) than those with L858R exon 21 (15 months) (p = 0.023). Patients with T790M mutation who received osimertinib after progression had longer median OS (41 months vs. 23 months, p = 0.0001). Median time to CNS progression was 13.9 months (48 patients). Longer time to CNS progression correlated with longer OS (R2 = 0.89). Conclusions: Epidermal growth factor receptor tyrosine kinase inhibitor therapy, with or without locoregional therapy, is effective for advanced EGFR-mutant NSCLC patients with brain metastases. Exon 19 deletion patients had better prognosis.

20.
Sensors (Basel) ; 23(19)2023 Sep 27.
Article in English | MEDLINE | ID: mdl-37836939

ABSTRACT

The real-time monitoring of food freshness in refrigerators is of significant importance in detecting potential food spoiling and preventing serious health issues. One method that is commonly reported and has received substantial attention is the discrimination of food freshness via the tracking of volatile molecules. Nevertheless, the ambient environment of low temperature (normally below 4 °C) and high humidity (90% R.H.), as well as poor selectivity in sensing gas species remain the challenge. In this research, an integrated smart gas-tracking device is designed and fabricated. By applying pump voltage on the yttria-stabilized zirconia (YSZ) membrane, the oxygen concentration in the testing chamber can be manually tailored. Due to the working principle of the sensor following the mixed potential behavior, distinct differences in sensitivity and selectivity are observed for the sensor that operated at different oxygen concentrations. Typically, the sensor gives satisfactory selectivity to H2S, NH3, and C2H5OH at the oxygen concentrations of 10%, 30%, and 40%, respectively. In addition, an acceptable response/recovery rate (within 24 s) is also confirmed. Finally, a refrigerator prototype that includes the smart gas sensor is built, and satisfactory performance in discriminating food freshness status of fresh or semi-fresh is verified for the proposed refrigerator prototype. In conclusion, these aforementioned promising results suggest that the proposed integrated smart gas sensor could be a potential candidate for alarming food spoilage.


Subject(s)
Cold Temperature , Food , Humidity , Oxygen
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