BOAO Photometric Survey of Galactic Open Clusters. III. Czernik 24 and Czernik 27

We present BV CCD photometry for the open clusters Czernik 24 and Czernik 27. These clusters have never been studied before, and we provide, for the first time, the cluster parameters; reddening, distance, metallicity and age. Czernik 24 is an old open cluster with age 1.8 +/- 0.2 Gyr, metallicity [Fe/H]=-0.41 +/- 0.15 dex, distance modulus (m-M)_0 = 13.1 +/- 0.3 mag (d=4.1 +/- 0.5 kpc), and reddening E(B-V) = 0.54 +/- 0.12 mag. The parameters for Czernik 27 are estimated to be age = 0.63 +/- 0.07 Gyr, [Fe/H]= -0.02 +/- 0.10 dex, (m-M)_0 = 13.8 +/- 0.2 mag (d=5.8 +/- 0.5 kpc), and E(B-V) = 0.15 +/- 0.05 mag. The metallicity and distance values for Czernik 24 are consistent with the relation between the metallicity and the Galactocentric distance of other old open clusters. We find the metallicity gradient of 51 old open clusters including Czernik 24 to be Delta [Fe/H]/Delta R_gc= -0.064 +/- 0.009 dex/kpc.Comment: Accepted by the Journal of the Korean Astronomical Society, 2005 December issu

Photomodulating chiroptic behaviors in nanosegregated mesophase from a mixture system consisting of nonchiral bent-core and photo-responsive rod-like mesogens

In this study, photoresponsive (PR) nanosegregated mesophases were prepared from a mixture system consisting of nonchiral bent-core (BC) and PR rod-like mesogens. The circular dichroism (CD) intensities depended strongly on the thermotropic polymorphism (nematic or smectic A) of the PR mesogen embedded in the BC molecular helical nanofilaments. The CD intensities could be reversibly modulated by alternating irradiation with UV and visible light in the nanosegregated mesophases. The study results presented interesting information relevant to the development of novel chiroptical materials

Selective clamping hand-assisted laparoscopic partial nephrectomy for localized renal tumors: A novel technique

Purpose: In this study, we described our initial experience and analyze the learning curve of segmental renal artery branch clamping with hand-assisted laparoscopic partial nephrectomy (PN) using special instruments. Materials and Methods: We conducted a retrospective review of consecutive cases of hand-assisted laparoscopic PN (LPN) between May 2015 and April 2018. Patient demographics, tumor characteristics, perioperative details, postoperative complications, and warm ischemic time for segmental artery branch clamping were included in our analysis. We used the cumulative sum (CUSUM) method to generate learning curves. Results: Segmental renal artery branch clamping was successfully completed in 16 of 20 patients. The median tumor size was 2.9 cm (range, 1.7–7.0 cm), median operation time was 185 minutes (range, 140–245 minutes), median blood loss was 291 mL (range, 100–600 mL), and median hospital stay was 5 days (range, 4–7 days). The median selective ischemic time was 21 minutes (range, 16–35 minutes). No patient had postoperative complications, acute or delayed bleeding. The median pre- and postoperative serum creatinine levels (0.91 and 0.98 mg/dL, respectively), and the pre- and postoperative estimated glomerular filtration rate (89.7 and 79.6 mL/min per 1.73 m2, respectively) were similar. Upon visual assessment of the CUSUM plots, a downward inflection point for decreasing total operation time was observed in the 9th case and estimated blood loss in the 12th case. Conclusions: Our study shows that segmental renal artery branch clamping hand-assisted LPN for localized renal tumors is feasible, safe, and has a relatively short learning curve

Dislocation binding as an origin for the improvement of room temperature ductility in Mg alloys

Improving room temperature ductility and formability is a bottleneck for a wide industrial application of Mg alloys, but even the mechanism for the effect of alloying elements on the deformation behavior of Mg is not clearly known. Here, using a molecular dynamics simulation, we clarify the role of alloying elements in improving the room temperature ductility of Mg alloys: Solute atoms have stronger dislocation binding tendency and solid solution strengthening effect on basal slip planes than on non-basal slip planes, reduce the anisotropy in the critical resolved shear stress between slip systems, and eventually improves the room temperature ductility. We predict that any solute elements with a size difference from Mg can improve the room temperature ductility, once the alloying amount is carefully controlled. By proving the validity of the prediction experimentally, we provide a new guide for designing Mg alloys with improved room temperature ductility and formability.113sciescopu

Utilization of Municipal Solid Waste Incineration Bottom Ash as Fine Aggregate of Cement Mortars

Incineration bottom ash is generated by the incineration of solid waste. Household solid waste is increasing every year and so is incineration bottom ash. This is a problem to treat the incineration bottom ash because the ash has many toxic components. Cement composites can solve this problem and there are many studies for using the bottom ash as fine aggregate. To evaluate the usage of incineration bottom ash, compressive strength, mercury intrusion porosimetry, scanning electron microscopy-backscatter electron, X-ray diffraction, and toxicity characteristic leaching processes were performed. When using incineration bottom ash up to 20% of substitution, the compressive strength in all cases was increased. This study showed how the filler effect appeared well in the cement composites through the scanning electron microscopy-backscatter electron, and mercury intrusion porosimetry. X-ray diffraction indicated the possibility of an alkali-silica reaction of the aggregate with the components of incineration bottom ash. This problem is an obstacle to applying the incineration bottom ash as a fine aggregate. In addition, the toxicity characteristic leaching process was shown to be under the threshold of the Korean standard, however, this should nuanced by the consideration of amorphity. Comprehensively, incineration bottom ash could be used as a fine aggregate of up to 20% of substitution. However, the pre-treatment would need to eliminate or reduce alkali reactive components and heavy metals

Enhancement of the helical twisting power with increasing the terminal chain length of nonchiral bent-core molecules doped in a chiral nematic liquid crystal

In this work, we prepared a series of nonchiral bent-core molecules with different terminal alkoxy chain lengths, and measured the helical twisting power (HTP) of the bent-core molecules doped in a chiral nematic liquid crystal (N*LC). We investigated the doping effect through the colour change and spectral change due to the Bragg (selective) reflection and found that the bent-core molecules with longer alkoxy chains showed stronger HTP under chiral circumstances such as N*LC. Namely, not only the axial conformations at wings linked to the bent central unit but also the length of the alkoxy chains at the terminal positions of the bent-core molecules play an important role in the resulting unusual chiral behaviour. A preliminary stochastic dynamics simulation to determine the distribution of the chirality order parameters was made, being consistent with the present experimental result

Network Pharmacology Study to Reveal the Potentiality of a Methanol Extract of <i>Caesalpinia sappan</i> L. Wood against Type-2 Diabetes Mellitus

Caesalpinia sappan L. (CS) is widely used to treat diabetic complications in south-east Asia, specifically in traditional Chinese medicine. This study intends to explain the molecular mechanism of how chemical constituents of CS interrelate with different signaling pathways and receptors involved in T2DM. GC-MS was employed to identify the chemical compounds from the methanol extract of CS wood (MECSW). Lipinski’s rule of five was applied, and 33 bioactive constituents have been screened from the CS extract. After that, 124 common targets and 26 compounds associated with T2DM were identified by mining several public databases. Protein–protein interactions and compound-target network were constructed using the STRING database and Cytoscape tool. Protein–protein interactions were identified in 121 interconnected nodes active in T2DM and peroxisome proliferator-activated receptor gamma (PPARG) as key target receptors. Furthermore, pathway compound target (PCT) analysis using the merger algorithm plugin of Cytoscape revealed 121 nodes from common T2DM targets, 33 nodes from MECSW compounds and 9 nodes of the KEGG pathway. Moreover, network topology analysis determined “Fisetin tetramethyl ether” as the key chemical compound. The DAVID online tool determined seven signaling receptors, among which PPARG was found most significant in T2DM progression. Gene ontology and KEGG pathway analysis implied the involvement of nine pathways, and the peroxisome proliferator-activated receptor (PPAR) pathway was selected as the hub signaling pathway. Finally, molecular docking and quantum chemistry analysis confirmed the strong binding affinity and reactive chemical nature of fisetin tetramethyl ether with target receptors exceeding that of the conventional drug (metformin), PPARs agonist (rosiglitazone) and co-crystallized ligands, indicating that fisetin could be a potential drug of choice in T2DM management. This study depicts the interrelationship of the bioactive compounds of MECSW with the T2DM-associated signaling pathways and target receptors. It also proposes a more pharmaceutically effective substance, fisetin tetramethyl ether, over the standard drug that activates PPARG protein in the PPAR signaling pathway of T2DM

Diffusion in A15 Nb3Sn: An atomistic study

Detailed diffusion mechanism in the A15 Nb3Sn superconducting compound has been investigated using an atomistic simulation based on a newly developed interatomic potential for the Nb-Sn binary alloy system. In terms of volume diffusion, Sn atoms diffuse via Nb sites due to the structural feature of A15 Nb3Sn, and the calculated energetics shows that the diffusion of SnNb anti-site is easy whereas the formation of SnNb is rate determining. However, the calculated diffusivity shows that the experimentally observed growth kinetics of the Nb3Sn compound layer cannot be fully explained by volume diffusion. Grain boundary diffusion is predicted to be seven to fourteen orders of magnitude faster than the volume diffusion, which can sufficiently explain the known growth kinetics of the Nb3Sn layer. Accordingly, grain boundary diffusion is suggested as the governing diffusion mechanism in Nb3Sn. The fundamental understanding and the details of diffusion revealed in the present work will contribute to future studies for detailed analyzes of the alloying effects on the growth kinetics of the Nb3Sn compound.11Nsciescopu

Effect of Microstructure on Low-Temperature Fracture Toughness of a Submerged-Arc-Welded Low-Carbon and Low-Alloy Steel Plate

This study investigated the low-temperature fracture behavior of an 80-mm-thick low-carbon steel plate welded by submerged arc. The relationship between impact absorbed energy and ductility–brittle transition temperature (DBTT) based on the microstructures was evaluated through quantitative analysis on grain size and complex constituent phases using advanced EBSD technique. The microstructure formed differently depending on the heat affections, which determined fracture properties in a low-temperature environment. Among the various microstructures of the heat-affected zone (HAZ), acicular ferrite has the greatest resistance to low-temperature impact due to its fine interlocking formation and its high-angle grain boundaries