Crack Monitoring in Rotating Shaft Using Rotational Speed Sensor-Based Torsional Stiffness Estimation with Adaptive Extended Kalman Filters.

In this study, we present an alternative solution for detecting crack damages in rotating shafts under torque fluctuation by directly estimating the reduction in torsional shaft stiffness using the adaptive extended Kalman filter (AEKF) algorithm. A dynamic system model of a rotating shaft for designing AEKF was derived and implemented. An AEKF with a forgetting factor (λ) update was then designed to effectively estimate the time-varying parameter (torsional shaft stiffness) owing to cracks. Both simulation and experimental results demonstrated that the proposed estimation method could not only estimate the decrease in stiffness caused by a crack, but also quantitatively evaluate the fatigue crack growth by directly estimating the shaft torsional stiffness. Another advantage of the proposed approach is that it uses only two cost-effective rotational speed sensors and can be readily implemented in structural health monitoring systems of rotating machinery.

Rational Design of Multiamphiphilic Polymer Compatibilizers: Versatile Solubility and Hybridization of Noncovalently Functionalized CNT Nanocomposites.

The design of amphiphilic polymer compatibilizers for solubility manipulation of CNT composites was systematically generalized in this study. Structurally tailored multiamphiphilic compatibilizer were designed and synthesized by applying simple, high-yield reactions. This multiamphiphilic compatibilizer was applied for noncovalent functionalization of CNTs as well as provided CNTs with outstanding dispersion stability, manipulation of solubility, and hybridization with Ag nanoparticles (NPs). With regard to the dispersion properties, superior records in maximum concentration (2.88-3.10 mg/mL in chloroform), and mass ratio of the compatibilizer for good CNT dispersion (36 wt %) were achieved by MWCNTs functionalized with a multiamphiphilic block copolymer compatibilizer. In particular, the solubility limitations of MWCNT dispersion in solvents ranging from toluene (nonpolar) to aqueous solution (polar) are surprisingly resolved by introducing this multiamphiphilic polymer compatibilizer. Furthermore, this polymer compatibilizer allowed the synthesis of the hybrid CNT nanocomposites with Ag nanoparticles by an in situ nucleation process. As such, the multiamphiphilic compatibilizer candidate as a new concept for the noncovalent functionalization of CNTs can extend their use for a wide range of applications.

Clinical features of adult patients with secondary hemophagocytic lymphohistiocytosis from causes other than lymphoma: an analysis of treatment outcome and prognostic factors.

Although hemophagocytic syndrome (HS) featuring secondary hemophagocytic lymphohistiocytosis (HLH) has a grave prognosis, little is known about the natural course of the disease. Patients who showed the clinical features of HLH as well as tissue-proven hemophagocytosis when seen at Asan Medical Center between 1999 and 2010 were included in this analysis. Patients with proven lymphoma were excluded. The median age of our 23 study patients was 49 years. Epstein-Barr virus was suspected to have caused HS in 16 (70%) patients and hepatitis A virus in one patient. Twenty-two patients were treated, 13 according to the HLH protocol and nine using immunosuppressive agents such as corticosteroid and/or cyclosporine. Five patients undertook allogeneic hematopoietic cell transplantation (HCT) during their treatment-dependent relapse (n = 4) or responsive status (n = 1). After the median follow-up of 180 days, 17 (74%) died and six (26%) were alive. The median time from initial presentation until death was 41 days among those patients who died. The serum fibrinogen level ≥166 mg/dL determined at the initial visit was significantly associated with the survival time according to univariate analysis. The low histiocyte proportion in bone marrow and early initiation of treatment tended to correlate with a favorable outcome. On multivariate analysis, serum fibrinogen ≥166 mg/dL (hazard ratio, 0.175, P = 0.018) was an independent clinical factor for determining the patient survival time. Despite appropriate patient management, the outcome of HS featuring HLH was grave. The serum fibrinogen level at the initial presentation was significant, and selected patients obtained some benefit from allogeneic HCT.

Extraction of hyaluronic acid (HA) from rooster comb and characterization using flow field-flow fractionation (FlFFF) coupled with multiangle light scattering (MALS).

Hyaluronic acid (HA) was extracted in a relatively large scale from rooster comb using a method similar to that reported previously. The extraction method was modified to simplify and to reduce time and cost in order to accommodate a large-scale extraction. Five hundred grams of frozen rooster combs yielded about 500 mg of dried HA. Extracted HA was characterized using asymmetrical flow field-flow fractionation (AsFlFFF) coupled online to a multiangle light scattering detector and a refractive index detector to determine the molecular size, molecular weight (MW) distribution, and molecular conformation of HA. For characterization of HA, AsFlFFF was operated by a simplified two-step procedure, instead of the conventional three-step procedure, where the first two steps (sample loading and focusing) were combined into one to avoid the adsorption of viscous HA onto the channel membrane. The simplified two-step AsFlFFF yielded reasonably good separations of HA molecules based on their MWs. The weight average MW (M(w) ) and the average root-mean-square (RMS) radius of HA extracted from rooster comb were 1.20×10(6) and 94.7 nm, respectively. When the sample solution was filtered through a 0.45 µm disposable syringe filter, they were reduced down to 3.8×10(5) and 50.1 nm, respectively.

Pyrolysis kinetics and decomposition characteristics of pine trees.

Pine trees comprise over 35% of the forests in Korea, since 1989, pine wilt disease introduced via the Japanese pine sawyer has been infecting many of these trees. As a renewable resource, pine can be converted to bio-oil, gas, and char through pyrolysis. In this study, the pyrolysis characteristics of pine trees were investigated using thermogravimetric analyzer, with most of the materials decomposing between 330 and 370 degrees C at heating rates of 5-20 degrees C/min. The apparent activation energy increased from 145 to 302 kJ mol(-1) with increasing pyrolysis conversion. The kinetics of pine tree pyrolysis were experimentally and mathematically evaluated. The kinetic parameters were determined using nonlinear least-squares regression of the experimental data assuming first-order kinetics. It was found from the kinetic rate constants that the predominant reaction pathway was A (pine) to gas (C(1)-C(4)) rather than A to bio-oil at temperatures of 330-370 degrees C.

Caustic injury: can CT grading system enable prediction of esophageal stricture?

BACKGROUND: The aim of this study was to test the utility of our computed tomography (CT) grading system, compared with endoscopy, for association with the development of esophageal stricture in patients with caustic ingestion. METHODS: This retrospective case series involved 49 patients with caustic ingestion from 1998 to 2009. The degree of esophageal damage was graded using a scoring system based on the extent of esophageal wall edema and the damage in adjacent tissue as seen on thoracoabdominal CT scans. The presence of esophageal stricture was established by esophagography. Diagnostic performance was compared using receiver operating characteristic (ROC) analysis. Sensitivity and specificity were calculated for the grading system. RESULTS: The CT grading score results showed that grade III was the most common injury (20 cases, 40.8%), followed by grade IV (14 cases, 28.6%), grade II (9 cases, 18.4%), and grade I (6 cases, 12.2%). In addition, damage to the esophagus was significantly correlated with esophageal stricture when the extent of damage approached grades III and IV (p < 0.001). The CT grading system for esophageal stricture resulted in a slightly larger area under the receiver operating characteristic curve (0.90) compared with endoscopic grading system (0.79). The sensitivity and specificity of CT grading system were moderately higher than those of endoscopic grading system. CONCLUSION: Assessment of the degree of esophageal damage using CT, a noninvasive modality, in patients who visit the emergency department following caustic ingestion should be useful in estimating the occurrence of complications including esophageal stricture.

Pyrolysis characteristics and kinetics of oak trees using thermogravimetric analyzer and micro-tubing reactor.

In this work, pyrolysis characteristics were investigated using thermogravimetric analysis (TGA) at heating rates of 5-20 degrees C/min. Most of the materials were decomposed between 330 degrees C and 370 degrees C at each heating rate. The average activation energy was 236.2 kJ/mol when the pyrolytic conversion increased from 5% to 70%. The pyrolysis kinetics of oak trees was also investigated experimentally and mathematically. The experiments were carried out in a tubing reactor at a temperature range of 330-370 degrees C with a reaction time of 2-8 min. A lump model of combined series and parallel reactions for bio-oil and gas formation was proposed. The kinetic parameters were determined by nonlinear least-squares regression from the experimental data. It was found from the reaction kinetic constants that the predominant reaction pathway from the oak trees was to bio-oil formation rather than to gas formation at the investigated temperature range.

Size analysis of industrial carbon blacks by sedimentation and flow field-flow fractionation.

Carbon black is one of the most useful particulate materials in the industrial field. Among the various physical properties of carbon black, size and size distribution are the most important properties to affect the quality of a final product. However, it is difficult to measure the exact particle size of carbon black since it suffers unavoidable interference from flocculation. In this study, the effects of various factors on the dispersion of industrial carbon blacks were investigated for the determination of size and size distribution of carbon black particles. Sedimentation and flow field-flow fractionations (FIFFF) were used to determine the size of carbon black, and their optimum analytical conditions were tested by changing surfactant, pH, ionic strength, and method of dispersion. The results showed that surfactant structure and its concentration played significant roles in dispersion stability. Carbon black was dispersed well with a nonionic surfactant with a pH of around 8 and an ionic strength of 0.003 M. The mean diameters measured from two types of FFF and photon correlation spectroscopy are in good agreement. This study demonstrates the potential of sedimentation and flow FFF for analyzing highly adsorptive industrial particles and guides for sample preparation.