Evaluation of tensile properties using instrumented indentation technique for small scale testing

The Instrumented indentation technique (IIT) is a useful tool for estimating various mechanical properties such as tensile properties, fracture toughness, and residual stress by analyzing the load and depth curve. Unlike conventional test such as tensile test, CTOD, since IIT makes an indent with rigid indenter and measures load and depth continuously, it requires only a localized area and small area on the target material. IIT also has merits of simple specimen preparation and experimental procedure in terms of time and cost. Also, it can be applied to in-field structures nondestructively. In this study, we introduce a method for evaluating tensile properties, primary yield strength and tensile strength using representative stress-strain beneath the rigid spherical indenter through numerous investigations of instrumented indentation curves. Analytic models and procedures for estimating the mechanical characterization of materials using IIT are proposed. The representative stress-strain method directly correlates indentation stress and strain beneath indenter to true stress and strain of the tensile test by taking into account the plastic constraint effect. The experimental results from IIT were verified by comparing results from the uniaxial tensile test. In particular, the applications of IIT in small scale and localized area of materials are presented. Reference 1) D. Tabor: Hardness of metal, (first ed. Clarendon Press, New York, 1951) 2) W.C. Oliver and G.M. Pharr, J. Mater, Res, Vol. 7, (1992), p. 1564 3) S.-K. Kang, Y.-C. Kim, K.-H. Kim, J.-Y. Kim and D. Kwon, Int. J. Plast. 49, 1 (2013

Improving Core Bond Strength of Particleboard Through Particle Size Redistribution

Novel particleboard furnish mixtures were formulated to improve the core-bonding and screw-holding of industrial particleboard without increasing resin content or board density. Single-layer (uniform vertical density with core furnish only) and conventional 3-layer particleboards were manufactured at two density levels from four novel mixes plus control (unscreened industrial core furnish). Board mean and core density, internal bond strength, edge screw withdrawal resistance, and moduli of rupture and elasticity were measured.The core of commercial furniture-grade particleboard appears to contain too many fine particulates and insufficient coarser particles. Uniform density profile single-layer boards containing novel mixes with higher-coarse (>2 mm) and lower-fines

Carrier transport mechanisms of hybrid ZnO nanorod-polymer LEDs

A hybrid polymer-nanorod (NR) light-emitting diode (LED), consisting of a hole-conducting polymer poly (9-vinyl carbazole) (PVK) and ZnO nanorod (NR) composite, with the device structure of glass/indium-tin-oxide (ITO)/PEDOT:PSS/(PVK + ZnO nanorods)/Al is fabricated through a simple spin coating technique. TEM images shows inhomogeneous deposition and the agglomeration of ZnO NRs, which is explained through their low probability of adsorption on PVK due to two-dimensional structural property. In the current-voltage characteristics, negative differential resistance (NDR) phenomenon is observed corresponding to device structure without ZnO NRs. The carrier transport behavior in the LED device is well described by both ohmic and space-chargelimited-current (SCLC) mechanisms. Broad blue electroluminescence (EL) consisting of two sub peaks, are centered at 441 nm and the other at 495 nm, is observed, which indicates that the ZnO nanorod play a role as a recombination center for excitons. The red shift in the position of the EL compared to that photoluminescence is well explained through band offsets at the heterojunction between the PVK and ZnO NRs

Long-Term Results of Endoscopic Dilatation for Tracheal and Subglottic Stenosis

ObjectivesThe purpose of this study was to assess the long-term results of endoscopic dilatation of airway stenosis and to evaluate predictive factors for favorable results.MethodsFifty-four patients with tracheal and subglottic stenosis who underwent endoscopic dilatation with at least 12 months follow-up were enrolled in this study. We evaluated predictive factors for final treatment outcome such as stenosis length, location, characteristics, procedure type, and the severity of stenosis.ResultsThe final outcome of endoscopic dilatation showed a cure rate of 40.7%, improvement rate of 46.3%, and failure rate of 13.0%. Patients with mild stenosis or a shorter stenotic segment and those who underwent a touch-up procedure following tracheal resection with end-to-end anastomosis showed better outcomes. The cure rate of endoscopic dilatation for patients with shorter mild stenosis was 72.2%.ConclusionEndoscopic dilatation may be a primary treatment modality for patients with airway stenosis characterized by mild severity and a short stenotic segment

Biochemical characterization of a recombinant Japanese encephalitis virus RNA-dependent RNA polymerase

<p>Abstract</p> <p>Background</p> <p>Japanese encephalitis virus (JEV) NS5 is a viral nonstructural protein that carries both methyltransferase and RNA-dependent RNA polymerase (RdRp) domains. It is a key component of the viral RNA replicase complex that presumably includes other viral nonstructural and cellular proteins. The biochemical properties of JEV NS5 have not been characterized due to the lack of a robust <it>in vitro </it>RdRp assay system, and the molecular mechanisms for the initiation of RNA synthesis by JEV NS5 remain to be elucidated.</p> <p>Results</p> <p>To characterize the biochemical properties of JEV RdRp, we expressed in <it>Escherichia coli </it>and purified an enzymatically active full-length recombinant JEV NS5 protein with a hexahistidine tag at the N-terminus. The purified NS5 protein, but not the mutant NS5 protein with an Ala substitution at the first Asp of the RdRp-conserved GDD motif, exhibited template- and primer-dependent RNA synthesis activity using a poly(A) RNA template. The NS5 protein was able to use both plus- and minus-strand 3'-untranslated regions of the JEV genome as templates in the absence of a primer, with the latter RNA being a better template. Analysis of the RNA synthesis initiation site using the 3'-end 83 nucleotides of the JEV genome as a minimal RNA template revealed that the NS5 protein specifically initiates RNA synthesis from an internal site, U₈₁, at the two nucleotides upstream of the 3'-end of the template.</p> <p>Conclusion</p> <p>As a first step toward the understanding of the molecular mechanisms for JEV RNA replication and ultimately for the <it>in vitro </it>reconstitution of viral RNA replicase complex, we for the first time established an <it>in vitro </it>JEV RdRp assay system with a functional full-length recombinant JEV NS5 protein and characterized the mechanisms of RNA synthesis from nonviral and viral RNA templates. The full-length recombinant JEV NS5 will be useful for the elucidation of the structure-function relationship of this enzyme and for the development of anti-JEV agents.</p

Design of a dye-doped liquid crystal cell with a constant transmittance-difference contour map

Thus far, the trial-and-error method has been used to find the condition for a dye-doped liquid crystal cell with desired performances. In this paper, we report a systematic design process to find the condition for the desired performances without trial-and-error process

Impact of Controlling Nutritional Status score on short-term outcomes after carotid endarterectomy: a retrospective cohort study

Background Malnutrition and impaired immune responses significantly affect the clinical outcomes of patients with atherosclerotic stenosis. The Controlling Nutritional Status (CONUT) score has recently been utilized to evaluate perioperative immunonutritional status. This study aimed to evaluate the relationship between immunonutritional status, indexed by CONUT score, and postoperative complications in patients undergoing carotid endarterectomy (CEA). Methods We retrospectively evaluated 188 patients who underwent elective CEA between January 2010 and December 2019. The preoperative CONUT score was calculated as the sum of the serum albumin concentration, total cholesterol level, and total lymphocyte count. The primary outcome was postoperative complications within 30 days after CEA, including major adverse cardiovascular events, pulmonary complications, stroke, renal failure, sepsis, wounds, and gastrointestinal complications. Cox proportional hazards regression analysis was used to estimate the factors associated with postoperative complications during the 30-day follow-up period. Results Twenty-five patients (13.3%) had at least one major complication. The incidence of postoperative complications was identified more frequently in the high CONUT group (12 of 27, 44.4% vs. 13 of 161, 8.1%; p<0.001). Multivariate analyses showed that a high preoperative CONUT score was independently associated with 30-day postoperative complications (hazard ratio, 5.98; 95% confidence interval, 2.56–13.97; p<0.001). Conclusion Our results showed that the CONUT score, a simple and readily available parameter using only objective laboratory values, is independently associated with early postoperative complications