Teachers' use of motivational strategies in the synchronous online environment: A self-determination theory perspective.

With the development of synchronous videoconferencing technology, research on the professional practices of synchronous online teaching has been growing at an exponential rate. However, little is known about synchronous online teachers' use of motivational strategies, despite the important role of teachers in fostering student motivation. To address this gap, this mixed-methods study examined how synchronous online teachers utilized motivational strategies and explored the influence of the synchronous online environment on the use of motivational strategies. As an analytical framework, we drew on the need-supportive teaching principles of the self-determination theory, which present three types of motivational strategies: involvement, structure, and autonomy-support. The quantitative analysis of survey results collected from language teachers (N = 72) revealed the perception that autonomy-support and structure were relatively well suited to the online environment while involvement was difficult to implement. The qualitative analysis of follow-up interviews (N = 10) elucidated how the online environment influenced the teachers' use of each strategy while producing a new framework and specific strategy lists that may be applicable to synchronous online teaching. This study presents important theoretical implications regarding the application of self-determination theory in online education, while also providing practical implications for synchronous online teacher preparation and professional development.

Synthesis and anti-prion aggregation activity of acylthiosemicarbazide analogues.

Prions are infectious protein particles known to cause prion diseases. The biochemical entity of the pathogen is the misfolded prion protein (PrPSc) that forms insoluble amyloids to impair brain function. PrPSc interacts with the non-pathogenic, cellular prion protein (PrPC) and facilitates conversion into a nascent misfolded isoform. Several small molecules have been reported to inhibit the aggregation of PrPSc but no pharmacological intervention was well established thus far. We, here, report that acylthiosemicarbazides inhibit the prion aggregation. Compounds 7x and 7y showed almost perfect inhibition (EC50 = 5 µM) in prion aggregation formation assay. The activity was further confirmed by atomic force microscopy, semi-denaturing detergent agarose gel electrophoresis and real-time quaking induced conversion assay (EC50 = 0.9 and 2.8 µM, respectively). These compounds also disaggregated pre-existing aggregates in vitro and one of them decreased the level of PrPSc in cultured cells with permanent prion infection, suggesting their potential as a treatment platform. In conclusion, hydroxy-2-naphthoylthiosemicarbazides can be an excellent scaffold for the discovery of anti-prion therapeutics.

Chemical Chaperones to Inhibit Endoplasmic Reticulum Stress: Implications in Diseases.

The endoplasmic reticulum (ER) is responsible for structural transformation or folding of de novo proteins for transport to the Golgi. When the folding capacity of the ER is exceeded or excessive accumulation of misfolded proteins occurs, the ER enters a stressed condition (ER stress) and unfolded protein responses (UPR) are triggered in order to rescue cells from the stress. Recovery of ER proceeds toward either survival or cell apoptosis. ER stress is implicated in many pathologies, such as diabetes, cardiovascular diseases, inflammatory diseases, neurodegeneration, and lysosomal storage diseases. As a survival or adaptation mechanism, chaperone molecules are upregulated to manage ER stress. Chemical versions of chaperone have been developed in search of drug candidates for ER stress-related diseases. In this review, synthetic or semi-synthetic chemical chaperones are categorized according to potential therapeutic area and listed along with their chemical structure and activity. Although only a few chemical chaperones have been approved as pharmaceutical drugs, a dramatic increase in literatures over the recent decades indicates enormous amount of efforts paid by many researchers. The efforts warrant clearer understanding of ER stress and the related diseases and consequently will offer a promising drug discovery platform with chaperone activity.

Complementary Driving between 2D Heterostructures and Surface Functionalization for Surpassing Binary Logic Devices.

Recently, for overcoming the fundamental limits of conventional silicon technology, multivalued logic (MVL) circuits based on two-dimensional (2D) materials have received significant attention for reducing the power consumption and the complexity of integrated circuits. Compared with the conventional silicon complementary metal oxide semiconductor technology, new functional heterostructures comprising 2D materials can be readily implemented, owing to their unique inherent electrical properties. Furthermore, their process integration does not pose issues of lattice mismatch at junction interfaces. This facilitates the realization of new functional logic gate circuit configurations. However, the reported three-valued NOT gates (ternary inverters) based on 2D materials require stringent operating conditions and complex fabrication processes to obtain three distinct logic states. Herein, a general structure of MVL devices based on a simple series connection of 2D materials with partial surface functionalization is demonstrated. By arranging three 2D materials exhibiting p-type, ambipolar, and n-type conductivities, ternary inverter circuits can be established based on the complementary driving between 2D heterotransistors. This ternary inverter circuit can be further improved for quaternary inverter circuits by controlling the charge neutral point of partial ambipolar 2D materials using surface functionalization, which is an effective and nondestructive doping method for 2D materials.

Treatment of life-threatening acute osteomyelitis of the jaw during chemotherapy: a case report.

Oral and maxillofacial infection is a common complication in patients undergoing chemotherapy. The treatment of oral diseases in such patients differs from that administered to healthy patients. This paper reports a case of acute osteomyelitis of odontogenic origin following a recent chemotherapy session. The patient's condition was life-threatening because of neutropenic fever and sepsis that developed during the inpatient supportive care. However, the patient showed prompt recovery within 40 days following the use of appropriate antibiotics and routine dressing, without the requirement for surgical treatment, except tooth extraction. As seen in this case, patients undergoing chemotherapy are more susceptible to rapid progression of infections in the oral and maxillofacial areas. Therefore, accurate diagnosis through prompt clinical and radiological examination, identification of the extent of infection, and assessment of the patient's immune system are crucial for favorable outcomes. It is also necessary to eliminate the source of infection through appropriate administration of antibiotics. In particular, a broad-spectrum antibiotic with anti-pneumococcal activity is essential. Proper antibiotic administration and wound dressing are essential for infection control. Furthermore, close consultation with a hemato-oncologist is necessary for effective infection management based on the professional evaluation of patients' immune mechanisms.

Functionalized Organic Material Platform for Realization of Ternary Logic Circuit.

Negative differential resistance/transconductance (NDR/NDT) has been attracting significant attention as a key functionality in the development of multivalued logic (MVL) systems that can overcome the limits of conventional binary logic devices. A high peak-to-valley current ratio (PVCR) and more than double-peak transfer characteristics are required to achieve a stable MVL operation. In this study, an organic NDR (ONDR) device with double-peak transfer characteristics and a high peak-to-valley current ratio (PVCR; >102) is fabricated by utilizing an organic material platform for the development of a key element device for MVL applications. The organic NDT (ONDT) device is fabricated using a series connection of electron-dominant (P(NDI2OD-Se2)) and hole-dominant (P(DPP2DT-T2)) channel ambipolar organic field-effect transistors (AOFETs), and the NDR feature is achieved via correlated biasing of the ONDT device. The PVCR of the ONDT device can reach up to 13,000 via carrier transfer modulation of the AOFETs by varying the PMMA:P(VDF-TrFE) ratio of the mixed layer that is used as the top-gate dielectric of each AOFET. Further, ternary latch circuit operation is demonstrated using the developed ONDR device that stores three logic states with three distinct and controllable output states by adjusting the PMMA:P(VDF-TrFE) ratio of the dielectric layer.

Scalable Two-Dimensional Lateral Metal/Semiconductor Junction Fabricated with Selective Synthetic Integration of Transition-Metal-Carbide (Mo2C)/-Dichalcogenide (MoS2).

The construction of manufacturable, stable, high-quality metal/semiconductor junction structures is of fundamental importance to implement higher-level devices and circuit systems. Owing to the unique features of two-dimensional (2D) materials, namely, that intralayer atoms are covalently bonded, whereas interlayer atoms are held together by weak attractive interactions, there are several studies on the fabrication and identification of the peculiar properties of various 2D heterostructures. However, large-scale 2D lateral metal/semiconductor junction structures with acceptable levels of manufacturability and quality have not yet been demonstrated, which is among the critical technological hurdles to overcome for the realization of 2D material-based electronic and photonic devices. This paper reports the fabrication of a manufacturable large-scale metal (Mo2C)/semiconductor (MoS2) junction via selective synthetic integration and a lithographically patterned SiO2 masking layer. It is demonstrated that whereas chemical conversion to Mo2C occurs in the exposed chemical vapor deposition-grown MoS2 part, the MoS2 layer under the SiO2 masking layer is protected from chemical conversion, so that a scalable Mo2C/MoS2 heterostructure is integrated down to nanometer-scale dimensions. Excellent contact resistance of 2.1 kΩ·µm is achieved from this lateral junction structure, providing a manufacturable and highly stable metal/semiconductor building block for real implementation of 2D material-based nanoscale device integration.

Avalanche Carrier Multiplication in Multilayer Black Phosphorus and Avalanche Photodetector.

A highly sensitive avalanche photodetector (APD) is fabricated by utilizing the avalanche multiplication mechanism in black phosphorus (BP), where a strong avalanche multiplication of electron-hole pairs is observed. Owing to the small bandgap (0.33 eV) of the multilayer BP, the carrier multiplication occurs at a significantly lower electric field than those of other 2D semiconductor materials. In order to further enhance the quantum efficiency and increase the signal-to-noise (S/N) ratio, Au nanoparticles (NPs) are integrated on the BP surface, which improves the light absorption by plasmonic effects. The BP-Au-NPs structure effectively reduces both dark current (≈10 times lower) and onset of avalanche electric field, leading to higher carrier multiplication, photogain, quantum efficiency, and S/N ratio. For the BP-Au-NPs APD, it is obtained that the external quantum efficiency (EQE) is 382 and the responsivity is 160 A W-1 at an electric field of 5 kV cm-1 (Vd ≈ 3.5 V, note that for the BP APD, EQE = 4.77 and responsivity = 2 A W-1 obtained at the same electric field). The significantly increased performance of the BP APD is promising for low-power-consumption, high-sensitivity, and low-noise photodevice applications, which can enable high-performance optical communication and imaging systems.

Plasmonic Transition Metal Carbide Electrodes for High-Performance InSe Photodetectors.

We demonstrate the application of MXenes, metallic 2D materials of transition-metal carbides, as excellent electrode materials for photonic devices. In this study, we have fabricated an InSe-based photodetector with a Ti2CTx electrode. The photodetector with few-layer, atomically thin, Ti2CTx (MXene) electrodes shows the avalanche carrier multiplication effect, which leads to high device performance. To improve the performance of the InSe/Ti2CTx avalanche photodetector, we can pattern Ti2CTx into nanoribbon arrays (a plasmonic grating structure), which enhances light absorption of the photodetector. The plasmonic InSe/Ti2CTx avalanche photodetector exhibits low dark current (3 nA), high responsivity (1 × 105 AW-1), and high detectivity (7.3 × 1012 Jones).

Epitaxial Synthesis of Molybdenum Carbide and Formation of a Mo2C/MoS2 Hybrid Structure via Chemical Conversion of Molybdenum Disulfide.

The epitaxial synthesis of molybdenum carbide (Mo2C, a 2D MXene material) via chemical conversion of molybdenum disulfide (MoS2) with thermal annealing under CH4 and H2 is reported. The experimental results show that adjusting the thermal annealing period provides a fully converted metallic Mo2C from MoS2 and an atomically sharp metallic/semiconducting hybrid structure via partial conversion of the semiconducting 2D material. Mo2C/MoS2 hybrid junctions display a low contact resistance (1.2 kΩ·µm) and low Schottky barrier height (26 meV), indicating the material's potential utility as a critical hybrid structural building block in future device applications. Density functional theory calculations are used to model the mechanisms by which Mo2C grows and forms a Mo2C/MoS2 hybrid structure. The results show that Mo2C conversion is initiated at the MoS2 edge and undergoes sequential hydrodesulfurization and carbide conversion steps, and an atomically sharp interface with MoS2 forms through epitaxial growth of Mo2C. This work provides the area-controllable synthesis of a manufacturable MXene from a transition metal dichalcogenide material and the formation of a metal/semiconductor junction structure. The present results will be of critical importance for future 2D heterojunction structures and functional device applications.

Generalized Scheme for High Performing Photodetectors with a p-Type 2D Channel Layer and n-Type Nanoparticles.

A generalized scheme for the fabrication of high performance photodetectors consisting of a p-type channel material and n-type nanoparticles is proposed. The high performance of the proposed hybrid photodetector is achieved through enhanced photoabsorption and the photocurrent gain arising from its effective charge transfer mechanism. In this paper, the realization of this design is presented in a hybrid photodetector consisting of 2D p-type black phosphorus (BP) and n-type molybdenum disulfide nanoparticles (MoS2 NPs), and it is demonstrated that it exhibits enhanced photoresponsivity and detectivity compared to pristine BP photodetectors. It is found that the performance of hybrid photodetector depends on the density of NPs on BP layer and that the response time can be reduced with increasing density of MoS2 NPs. The rising and falling times of this photodetector are smaller than those of BP photodetectors without NPs. This proposed scheme is expected to work equally well for a photodetector with an n-type channel material and p-type nanoparticles.

Identification of the Aggregation-sex Pheromone Produced by Male Monochamus saltuarius, a Major Insect Vector of the Pine Wood Nematode.

In this study, we isolated and identified an aggregation-sex pheromone from Monochamus saltuarius, the major insect vector of the pine wood nematode in Korea. Adult males of M. saltuarius produce 2-undecyloxy-1-ethanol, which is known as an aggregation-sex pheromone in other Monochamus species. We performed field experiments to determine the attractiveness of the pheromone and other synergists. More M. saltuarius adult beetles were attracted to traps baited with the pheromone than to unbaited traps. Ethanol and (-)-α-pinene interacted synergistically with the pheromone. Traps baited with the pheromone + (-)-α-pinene +ethanol were more attractive to M. saltuarius adults than traps baited with the pheromone, (-)-α-pinene, or ethanol alone. Ipsenol, ipsdienol, and limonene were also identified as synergists of the aggregation-sex pheromone for M. saltuarius adults. In field experiments, the proportion of females was much higher in the beetles caught in traps than among the beetles emerging from naturally-infested logs in the laboratory. Our results suggest that a combination of aggregation-sex pheromone and synergists could be very effective for monitoring and managing M. saltuarius.

Epitaxial Growth of Large-Grain NiSe Films by Solid-State Reaction for High-Responsivity Photodetector Arrays.

Film-based photodetectors have shown superiority for the fabrication of photodetector arrays, which are desired for integrating photodetectors into sensing and imaging systems, such as image sensors. But they usually possess a low responsivity due to low carrier mobility of the film consisting of nanocrystals. Large-grain semiconductor films are expected to fabricate superior-responsivity photodetector arrays. However, the growth of large-grain semiconductor films, normally with a nonlayer structure, is still challenging. Herein, this study introduces a solid-state reaction method, in which the growth rate is supposed to be limited by diffusion and reaction rate, for interface-confined epitaxial growth of nonlayer structured NiSe films with grain size up to micrometer scale on Ni foil. Meanwhile, patterned growth of NiSe films allows the fabrication of NiSe film based photodetector arrays. More importantly, the fabricated photodetector based on as-grown high-quality NiSe films shows a responsivity of 150 A W-1 in contrast to the value of 0.009 A W-1 from the photodetector based on as-deposited NiSe film consisting of nanocrystals, indicating a huge responsivity-enhancement up to four orders of magnitude. It is ascribed to the enhanced charge carrier mobility in as-grown NiSe films by dramatically decreasing the amount of grain boundary leading to scattering of charge carrier.

Atomic Layer Etching Mechanism of MoS2 for Nanodevices.

Among the layered transition metal dichalcogenides (TMDs) that can form stable two-dimensional crystal structures, molybdenum disulfide (MoS2) has been intensively investigated because of its unique properties in various electronic and optoelectronic applications with different band gap energies from 1.29 to 1.9 eV as the number of layers decreases. To control the MoS2 layers, atomic layer etching (ALE) (which is a cyclic etching consisting of a radical-adsorption step such as Cl adsorption and a reacted-compound-desorption step via a low-energy Ar+-ion exposure) can be a highly effective technique to avoid inducing damage and contamination that occur during the reactive steps. Whereas graphene is composed of one-atom-thick layers, MoS2 is composed of three-atom-thick S(top)-Mo(mid)-S(bottom) layers; therefore, the ALE mechanisms of the two structures are significantly different. In this study, for MoS2 ALE, the Cl radical is used as the adsorption species and a low-energy Ar+ ion is used as the desorption species. A MoS2 ALE mechanism (by which the S(top), Mo(mid), and S(bottom) atoms are sequentially removed from the MoS2 crystal structure due to the trapped Cl atoms between the S(top) layer and the Mo(mid) layer) is reported according to the results of an experiment and a simulation. In addition, the ALE technique shows that a monolayer MoS2 field effect transistor (FET) fabricated after one cycle of ALE is undamaged and exhibits electrical characteristics similar to those of a pristine monolayer MoS2 FET. This technique is also applicable to all layered TMD materials, such as tungsten disulfide (WS2), molybdenum diselenide (MoSe2), and tungsten diselenide (WSe2).

Analysis of the outcome of young age tongue squamous cell carcinoma.

BACKGROUND: The incidence of tongue squamous cell carcinoma (TSCC) in young patients has recently increased, and these TSCCs are believed to be etiologically distinct from those in older patients, who have longer exposure to risk factors such as tobacco and alcohol. The prognosis of TSCCs in young patients remains controversial. METHODS: We retrospectively reviewed the records of 117 patients (2001-2011) who were diagnosed with squamous cell carcinoma of the oral tongue. Patients were divided into two age groups, older (ages over 40) and younger (ages 40 and younger). Data were compared between the two groups, and survival rates were analyzed. RESULTS: The results show that there are significant differences in overall, disease-free, and distant metastasis-free survival rates between the two groups. Five-year overall survival rates were 70% in older patients and 42% in young patients (p = 0.033). Five-year disease-free survival rates were 73% in older patients and 40% in young patients (p = 0.011), and 5-year distant metastasis-free survival rates were 97% in older patients and 62% in young patients (p = 0.033).Multivariate analysis revealed that histologic grade was the only independent risk factor for overall survival in both groups of patients (p = 0.002, HR = 2.287). The analysis also demonstrated that age was the critical risk factor for distant metastasis (p = 0.046, HR = 9.687). CONCLUSION: In this study, young (ages 40 and younger) patients with squamous cell carcinoma of the oral tongue had a higher rate of distant metastasis and a worse prognosis. Accordingly, we propose the necessity of an extensive therapeutic regimen that should be used in all young patients with TSCC.

A homogeneous atomic layer MoS2(1-x)Se2x alloy prepared by low-pressure chemical vapor deposition, and its properties.

We report the growth of large-area monolayer MoS2(1-x)Se2x alloys with controlled morphologies using a low-pressure chemical vapor deposition (CVD) method. MoS2(1-x)Se2x alloys with different morphologies, created using the same growth time, have been observed by controlling the gaseous MoO3 precursor on substrates placed in regions with different temperatures. TEM observations clearly reveal that the as-synthesized monolayer MoS2(1-x)Se2x alloy is crystalline, with a hexagonal structure. XPS, Raman mapping, and EDS mapping clearly show the homogeneous substitution of ∼2 atomic weight % Se through the whole crystal. Compared with a pristine CVD-grown monolayer of MoS2, the optical band gap differs by 4.52%, from 1.77 eV to 1.69 eV. Additionally, back-gated transistors fabricated on the monolayer MoS2(1-x)Se2x alloy exhibit n-type behavior at a current on/off ratio of ∼104 and a high mobility value of 8.4 cm2 V-1 s-1.

Phosphorene/rhenium disulfide heterojunction-based negative differential resistance device for multi-valued logic.

Recently, negative differential resistance devices have attracted considerable attention due to their folded current-voltage characteristic, which presents multiple threshold voltage values. Because of this remarkable property, studies associated with the negative differential resistance devices have been explored for realizing multi-valued logic applications. Here we demonstrate a negative differential resistance device based on a phosphorene/rhenium disulfide (BP/ReS2) heterojunction that is formed by type-III broken-gap band alignment, showing high peak-to-valley current ratio values of 4.2 and 6.9 at room temperature and 180 K, respectively. Also, the carrier transport mechanism of the BP/ReS2 negative differential resistance device is investigated in detail by analysing the tunnelling and diffusion currents at various temperatures with the proposed analytic negative differential resistance device model. Finally, we demonstrate a ternary inverter as a multi-valued logic application. This study of a two-dimensional material heterojunction is a step forward toward future multi-valued logic device research.

Size-tunable synthesis of monolayer MoS2 nanoparticles and their applications in non-volatile memory devices.

We report the CVD synthesis of a monolayer of MoS2 nanoparticles such that the nanoparticle size was controlled over the range 5-100 nm and the chemical potential of sulfur was modified, both by controlling the hydrogen flow rate during the CVD process. As the hydrogen flow rate was increased, the reaction process of sulfur changed from a "sulfiding" process to a "sulfo-reductive" process, resulting in the growth of smaller MoS2 nanoparticles on the substrates. The size control, crystalline quality, chemical configuration, and distribution uniformity of the CVD-grown monolayer MoS2 nanoparticles were confirmed. The growth of the MoS2 nanoparticles at different edge states was studied using density functional theory calculations to clarify the size-tunable mechanism. A non-volatile memory device fabricated using the CVD-grown size-controlled 5 nm monolayer MoS2 nanoparticles as a floating gate showed a good memory window of 5-8 V and an excellent retention period of a decade.

M-DNA/Transition Metal Dichalcogenide Hybrid Structure-based Bio-FET sensor with Ultra-high Sensitivity.

Here, we report a high performance biosensor based on (i) a Cu2+-DNA/MoS2 hybrid structure and (ii) a field effect transistor, which we refer to as a bio-FET, presenting a high sensitivity of 1.7 × 103 A/A. This high sensitivity was achieved by using a DNA nanostructure with copper ions (Cu2+) that induced a positive polarity in the DNA (receptor). This strategy improved the detecting ability for doxorubicin-like molecules (target) that have a negative polarity. Very short distance between the biomolecules and the sensor surface was obtained without using a dielectric layer, contributing to the high sensitivity. We first investigated the effect of doxorubicin on DNA/MoS2 and Cu2+-DNA/MoS2 nanostructures using Raman spectroscopy and Kelvin force probe microscopy. Then, we analyzed the sensing mechanism and performance in DNA/MoS2- and Cu2+-DNA/MoS2-based bio-FETs by electrical measurements (ID-VG at various VD) for various concentrations of doxorubicin. Finally, successful operation of the Cu2+-DNA/MoS2 bio-FET was demonstrated for six cycles (each cycle consisted of four steps: 2 preparation steps, a sensing step, and an erasing step) with different doxorubicin concentrations. The bio-FET showed excellent reusability, which has not been achieved previously in 2D biosensors.

Photodetectors: Broad Detection Range Rhenium Diselenide Photodetector Enhanced by (3-Aminopropyl)Triethoxysilane and Triphenylphosphine Treatment (Adv. Mater. 31/2016).

The effects of triphenylphosphine (PPh3 ) and (3-amino-propyl)triethoxysilane (APTES) on a rhenium diselenide (ReSe2 ) photodetector are systematically studied by J.-H. Park and co-workers on page 6711 in comparison with a conventional MoS2 device. A very high performance ReSe2 photodetector is demonstrated, which has a broad photodetection range, high photoresponsivity (1.18 × 10(6) A W(-1) ), and fast photoswitching speed (rising/decaying time: 58/263 ms).