Use of Adjacent Knot Data in Predicting Bending Strength of Dimension Lumber by X-Ray

In a previous study, the knot depth ratio (KDR) evaluation method was proposed to quantify the area of knots in a cross-section. That study reported that bending strength can be predicted by KDR analysis. However, the KDR model did not take into consideration the additional strength reduction caused by adjacent knots. It was found that the prediction of lumber strength was improved when adjacent knots were taken into consideration. Analysis using the KDRA (KDR adding knots) model revealed that the optimum cross-sectional interval, an input variable, is directly affected by knot size parallel to lumber length (KSPLL). KSPLL depends on the sawing method and log characteristics, and for species containing large knots, the cross-sectional interval is likely to be extremely wide. This can cause several adjacent small knots to be excluded from the analysis, requiring modification of the KDRA model algorithm. This modification resulted in improvement in the precision of the strength prediction, although the input variable of the cross-sectional interval was not used. The R2 values obtained using this method were 0.60 and 0.56 for Japanese larch and red pine, respectively

Electroactive Artificial Muscles Based on Functionally Antagonistic Core–Shell Polymer Electrolyte Derived from PS-b-PSS Block Copolymer

Electroactive ionic soft actuators, a type of artificial muscles containing a polymer electrolyte membrane sandwiched between two electrodes, have been intensively investigated owing to their potential applications to bioinspired soft robotics, wearable electronics, and active biomedical devices. However, the design and synthesis of an efficient polymer electrolyte suitable for ion migration have been major challenges in developing high-performance ionic soft actuators. Herein, a highly bendable ionic soft actuator based on an unprecedented block copolymer is reported, i.e., polystyrene-b-poly(1-ethyl-3-methylimidazolium-4-styrenesulfonate) (PS-b-PSS-EMIm), with a functionally antagonistic core–shell architecture that is specifically designed as an ionic exchangeable polymer electrolyte. The corresponding actuator shows exceptionally good actuation performance, with a high displacement of 8.22 mm at an ultralow voltage of 0.5 V, a fast rise time of 5 s, and excellent durability over 14 000 cycles. It is envisaged that the development of this high-performance ionic soft actuator could contribute to the progress toward the realization of the aforementioned applications. Furthermore, the procedure described herein can also be applied for developing novel polymer electrolytes related to solid-state lithium batteries and fuel cells

Effect of W/C Ratio on Durability and Porosity in Cement Mortar with Constant Cement Amount

Water is often added to concrete placing for easy workability and finishability in construction site. The additional mixing water can help easy mixing and workability but causes increased porosity, which yields degradation of durability and structural performances. In this paper, cement mortar samples with 0.45 of W/C (water to cement) ratio are prepared for control case and durability performances are evaluated with additional water from 0.45 to 0.60 of W/C. Several durability tests including strength, chloride diffusion, air permeability, saturation, and moisture diffusion are performed, and they are analyzed with changed porosity. The changing ratios and patterns of durability performance are evaluated considering pore size distribution, total porosity, and additional water content

Microscopic evidence of strong interactions between chemical vapor deposited 2D MoS2 film and SiO2 growth template

Two-dimensional MoS2 film can grow on oxide substrates including Al2O3 and SiO2. However, it cannot grow usually on non-oxide substrates such as a bare Si wafer using chemical vapor deposition. To address this issue, we prepared as-synthesized and transferred MoS2 (AS-MoS2 and TR-MoS2) films on SiO2/Si substrates and studied the effect of the SiO2 layer on the atomic and electronic structure of the MoS2 films using spherical aberration-corrected scanning transition electron microscopy (STEM) and electron energy loss spectroscopy (EELS). The interlayer distance between MoS2 layers film showed a change at the AS-MoS2/SiO2 interface, which is attributed to the formation of S–O chemical bonding at the interface, whereas the TR-MoS2/SiO2 interface showed only van der Waals interactions. Through STEM and EELS studies, we confirmed that there exists a bonding state in addition to the van der Waals force, which is the dominant interaction between MoS2 and SiO2. The formation of S–O bonding at the AS-MoS2/SiO2 interface layer suggests that the sulfur atoms at the termination layer in the MoS2 films are bonded to the oxygen atoms of the SiO2 layer during chemical vapor deposition. Our results indicate that the S–O bonding feature promotes the growth of MoS2 thin films on oxide growth templates.This work was fnancially supported by National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (2018M3D1A1058793, 2019M3E6A1103818, 2020M2D8A206983011, 2021R1A2B5B03001851). The Inter-University Semiconductor Research Center and Institute of Engineering Research at Seoul National University provided research facilities for this work

Strongyloidiasis Presenting as Yellowish Nodules in Colonoscopy of an Immunocompetent Patient

Strongyloides stercoralis is endemic to tropical and subtropical regions, and infections are usually asymptomatic. However, immunocompromised patients, such as those receiving immunosuppressive therapy, high-dose steroids, or chemotherapy, can develop fatal hyperinfections. An 84-year-old man without any symptoms was diagnosed with strongyloidiasis during a regular screening colonoscopy. His medical history only involved a gastric endoscopic submucosal dissection for early gastric cancer 6 months previously. Few cases have been published about asymptomatic strongyloidiasis diagnosed in an immunocompetent host via endoscopic mucosal resection with characteristic colonoscopic findings. We report a case of colon-involved asymptomatic strongyloidiasis with specific colonic findings of yellowish-white nodules. This finding may be an important marker of S. stercoralis infection, which could prevent hyperinfections

Usefulness of endoscopic resection using the band ligation method for rectal neuroendocrine tumors

Background/AimsRectal neuroendocrine tumors (NETs) are among the most common of gastrointestinal NETs. Due to recent advances in endoscopy, various methods of complete endoscopic resection have been introduced for small (≤10 mm) rectal NETs. However, there is a debate about the optimal treatment for rectal NETs. In our study, we aimed to evaluate the efficacy and feasibility of endoscopic resection using pneumoband and elastic band (ER-BL) for rectal NETs smaller than 10 mm in diameter.MethodsA total of 55 patients who were diagnosed with rectal NET from January 2004 to December 2011 at Gil Medical Center were analyzed retrospectively. Sixteen patients underwent ER-BL. For comparison, 39 patients underwent conventional endoscopic mucosal resection (EMR).ResultsThere was a markedly lower deep margin positive rate for ER-BL than for conventional EMR (6% [1/16] vs. 46% [18/39], P=0.029). Four patients who underwent conventional EMR experienced perforation or bleeding. However, they recovered within a few days. On the other hand, patients whounderwent endoscopic resection using a pneumoband did not experience any complications. In multivariate analysis, ER-BL (P=0.021) was independently associated with complete resection.ConclusionsER-BL is an effective endoscopic treatment with regards to deep margin resection for rectal NET smaller than 10 mm