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.
Ketone body production, an alternative fuel upon low glucose availability, reduces hepatic fat accumulation. However, its clinical implications have not been established in patients with nonalcoholic ...fatty liver disease (NAFLD). We investigated the association between spontaneous fasting ketonuria and liver fibrosis in patients with NAFLD without prediabetes and diabetes mellitus (DM). A total of 6202 patients with ultrasound confirmed NAFLD without prediabetes and DM were enrolled in the study. Using low cut off values of NAFLD fibrosis score (NFS) and fibrosis-4, liver fibrosis was defined as an intermediate–high probability of advanced liver fibrosis. Of the 6202 NAFLD patients, 360 (5.8%) had ketonuria. Compared to the patients without ketonuria, patients with ketonuria were younger (41.1 vs. 44.6 years, p < 0.001), had lower levels of glucose (87.2 vs. 91.0 mg/dL, p < 0.001), and homeostatic model assessment for insulin resistance (1.0 vs. 1.5, p < 0.001). The presence of ketonuria had an inverse association with liver fibrosis, assessed using both NFS (final adjusted odds ratio aOR, 0.67; 95% confidence interval CI, 0.45–1.01) and fibrosis-4 (aOR, 0.58; 95% CI, 0.40–0.84). The presence of ketonuria in NAFLD patients without prediabetes and DM may have favorable metabolic effects compared to the absence of ketonuria, independent of traditional metabolic factors.
•An 4D printed SMC actuator was fabricated using SMA and SMP with a FDM 3D printer.•A volume fraction of SMA:SMP of 1:5 showed the largest length change of 8 mm, and the most rapid response time of 4 ...s.•The reversible actuator mechanism explains the SMC actuation via each shape memory effect.•SMC showed potential application for stents and valve controllers via 3D printing technology to achieve customized designs.
A fused deposition modeling (FDM) tool was used to fabricate a shape memory composite (SMC) that combined a shape memory alloy (SMA) with a shape memory polymer (SMP). The SMA caused a shape memory effect due to a phase change between martensite and austenite phases, in turn due to a temperature change. Also, the SMP had a shape memory effect caused by changes in the proportions of hard and soft segments near the glass transition temperature (Tg). Usually, common SMAs and SMPs are not reversible, so these materials do not go back to their original shapes once they are deformed. In this study, we fabricated 4D printing actuator via reversible SMC actuations using 3D printing technology. Nylon 12 was used as the 3D printing material in filament form. Moreover, the volume fraction of SMA to SMP was varied to find the optimum ratio for good operation cycles. A volume fraction of SMA:SMP of 1:5 showed the largest length change, of 8 mm, and the most rapid response time, of 4 s in overall dimension of 140mm×10mm×1mm (length×width×thickness).Thus, the SMC showed promising results for the application of stents and valve controllers that could be manufactured by 3D printing technology.
Oxidation‐initiated Nazarov reactions of 1,4‐pentadien‐3‐yl ethers take place in the presence of DDQ. Termination by regioselective elimination preserves both stereocenters created during ...electrocyclization, providing cyclopentanone products bearing an exocyclic methylene unit. Use of catalytic DDQ with MnO2 as terminal oxidant is also described.
Dehydrogenative Nazarov reaction: 1,4‐Pentadien‐3‐yl ethers undergo oxidative conversion to the corresponding 3‐alkoxypentadienyl cations followed by clean Nazarov cyclization and regioselective exocyclic elimination to furnish alkylidene cyclopentenol ethers with the net loss of H2. This method provides mild, Lewis acid‐free access to Nazarov products in which the stereogenic centers formed in the electrocyclization are preserved.
Stent length has been considered an important predictor of adverse events after percutaneous coronary intervention, even with the first-generation drug-eluting stents (DESs). The introduction of ...newer-generation DES has further reduced the rates of adverse clinical events such as restenosis, myocardial infarction, and stent thrombosis. The aim of this study was to compare the impact of stent length on the long-term clinical outcomes between first- and newer-generation DESs. The effects of stent length (≥32 vs <32 mm) on the clinical outcomes were evaluated in 8,445 patients who underwent percutaneous coronary intervention using either a first-generation DES (sirolimus- and paclitaxel-eluting stents, n = 6,334) or a newer-generation DES (everolimus- and zotarolimus-eluting stents, n = 2,111) from January 2004 to December 2009. The 3-year adverse outcomes (composite of all-cause death, nonfatal myocardial infarction, target vessel revascularization, and stent thrombosis) were compared using the inverse probability of treatment-weighted method according to the stent length. After adjustment for differences in the baseline risk factors, a stent length of ≥32 mm was significantly associated with higher cumulative rates of target vessel revascularization and stent thrombosis in the patients treated with a first-generation DES (adjusted hazard ratio 1.875, 95% confidence interval 1.531 to 2.297, p <0.001; adjusted hazard ratio 2.964, 95% confidence interval 1.270 to 6.917, p = 0.012), but it was not associated with the clinical outcomes in patients treated with a newer-generation DES. In conclusion, stent length might not be associated with long-term clinical outcomes in newer-generation DES era, whereas stent length might be associated with long-term clinical outcomes in the first-generation DESs.
The energy slab is a novel type of horizontal Ground Heat Exchanger (GHEX), where heat exchange pipes are encased in building slab structures. The thermal performance of energy slabs is usually ...inferior to the conventional closed-loop vertical GHEX because its installation depth is relatively shallow and therefore affected by ambient air temperature. In this paper, heat exchange pipes were made of not only conventional high-density polyethylene (HDPE), but also stainless steel (STS), which is expected to enhance the thermal performance of the energy slabs. In addition to a floor slab, a side wall slab was also used as a component of energy slabs to maximize the use of geothermal energy that can be generated from the underground space. Moreover, a thermal insulation layer in the energy slabs was considered in order to reduce thermal interference induced by ambient air temperature. Consequently, two different field-scale energy slabs (i.e., floor-type and wall-type energy slabs) were constructed in a test bed, and two types of heat exchange pipes (i.e., STS pipe and HDPE pipes) were installed in each energy slab. A series of thermal response tests (TRTs) and thermal performance tests (TPTs) were conducted to evaluate the heat exchange performance of the constructed energy slabs. Use of the STS heat exchange pipe enhanced the thermal performance of energy slabs. Additionally, the wall-type energy slab had a similar thermal performance to the floor-type energy slab, which infers the applicability of the additional use of the wall-type energy slab. Note that if an energy slab is not thermally cut off from the building’s interior space with the aid of thermal insulation layers, heat exchange within the energy slabs should be significantly influenced by fluctuations in ambient temperature.
•This study analyzes jobplanet reviews using TF-IDF and LDA to study job satisfaction.•It compares SMEs' and large corporations' employee reviews on pros and cons.•Large corporation employees valued ...growth and respect but complained of excessive workloads.•SME employees valued communication and flexible leave but noted long hours and lack of vision.•Study concludes that a clear vision, horizontal culture, and growth impact job satisfaction.
This study analyzes online company reviews from JobPlanet using TF-IDF analysis and LDA topic modeling to explore factors influencing job satisfaction in Korea. By comparing the reviews from employees at small and medium-sized enterprises (SMEs) and large corporations on the advantages and disadvantages, it aims to gain insights into enhancing SMEs' competitiveness regarding employee job satisfaction.
The analysis shows that large corporation employees valued personal growth and mutual respect but cited excessive workload as a significant drawback. SME employees appreciated smooth communication and flexible leave but noted unilateral work, long hours, and lack of shared vision. The study concludes that a horizontal organizational culture and opportunities for personal growth significantly impact job satisfaction beyond salary and benefits. SMEs can improve competitiveness by fostering a clear corporate vision, a horizontal culture, and personal growth opportunities.
Understanding the transport of naturally abundant clay colloids is critical in colloid associated contaminant transport in porous media. This study was focused on the impact of the median size of ...sand grains and the ionic strength of solution on the transport and retention behavior of clay colloids. Two clay samples of kaolinite and illite colloids were selected to represent clay samples containing 1:1 and 2:1 clay minerals, respectively. The observed retention profiles and breakthrough curves demonstrated that the impact of ionic strength on the retention behavior of clay was consistent with other colloidal colloids such as latex colloids or graphene oxide. The quantity of the retained clay increased as the median sizes of sand decreased, and the ionic strength increased from 0 to 0.1 M. However, a similar quantity of retained illite at the ionic strength of 0.01 M and 0.1 M indicates the presence of threshold ionic strength in clay colloid retention. The exponential relationship between sand-to-clay size ratio and first-order retention coefficient at given ionic strength implies the chance in long-term prediction of clay colloid transport from the observed retention profiles.
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•Transport of kaolinite and illite was investigated in saturated sand column.•Quantity of retained clay does not increase for ionic strength greater than 0.01 M.•Porosity of sand can be a critical factor in clay particle transport.•Impact of aggregation and aspect ratio of clay particles should be considered.
•As the Sb element is substituted for Bi, the unit cell of LTP Mn-Bi shrinks.•The enhancement of the Hc by the substitution of Sb is due to the grain refinement effect.•The (BH)max of Mn54Bi44.5Sb1.5 ...sample is recorded at 3.27 MGOe, which is increased from 0.15 MGOe for the Sb-free sample.•Substitution of Sb into LTP Mn-Bi can significantly improve the Hc at low temperatures.
We optimized the composition of Mn-Bi alloy, examined the effects of third element substitution of Sn, Cu, Al, and Sb on the magnetic properties, and investigated the microstructures and magnetic properties of Sb substituted Mn-Bi annealed ribbons. The optimized composition was Mn54Bi46, and it was found that the Sb substitution had the most positive effects on the magnetic properties among the substitution elements. Thus, we accomplished a detailed investigation on Mn54Bi46-xSbx (0.0 ≤ x ≤ 5.0) annealed ribbons. The fracture planes of the annealed ribbons revealed that the grain size drastically decreased from a few tens of microns to submicrons close to the single domain size, which substantially enhanced the coercivity (Hc), remanent magnetization (Mr), and maximum energy product ((BH)max). As a result, as the Sb content changed from 0 to 1.5, the Mr, Hc, and (BH)max of randomly oriented samples increased significantly from 14.7 emu/g, 0.50 kOe, and 0.15 MGOe to 37.2 emu/g, 8.15 kOe, and 3.27 MGOe, respectively. Furthermore, the temperature dependence of Hc on the Sb substitution showed significant enhancement over a wide temperature range from 223 to 378 K, suggesting that Mn-Bi alloy can be used in electrical vehicles.
Among various types of ground heat exchangers (GHEXs or GHEs), a coaxial-type GHEX exhibits outstanding thermal performance owing to the geometric characteristics of the concentric tube-in-tube ...configuration. In this study, the unique configuration of the coaxial-type GHEX was investigated through parametric studies, which provided the energy efficient configuration. A computational fluid dynamics (CFD) model was developed and verified by using the field test results for the coaxial-type GHEX constructed in a test bed. Then, the parametric studies were conducted using the developed CFD model for various influential factors (i.e., flow rate of a circulating fluid, hydraulic diameter, and thermal conductivities of inner pipe and bentonite grout), which were selected considering the tube-in-tube configuration. The thermal performance of the coaxial-type GHEX increased with an increase in the flow rate of a circulating fluid and the thermal conductivity of bentonite grout. In addition, the inner pipes of the coaxial-type GHEX should be composed of materials with a thermal conductivity lower than 0.025 W/(m⋅K) to relieve thermal interference between the outer and inner pipes. Notably, it was concluded that the coaxial-type GHEX should be designed to secure the sufficient heat exchangeable area and retention capacity of the circulating fluid.
•Effect of tube-in-tube configuration in coaxial-type GHEX was investigated.•Tube-in-tube configuration increases energy efficient flow rate.•Fluid retention time and heat exchange area govern overall thermal performance.•Inner pipe made of Polyurethane effectively relieves thermal interference.
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