Stress states investigation of adhesive bonded joint between spar cap and shear webs of a large wind turbine rotor blade

Journal of Mechanical Science and Technology - The debonding failure at the adhesive bonded joints between spar caps and shear webs is one of failure modes of the wind turbine rotor blades. To...     

Insulation System Using High-Temperature Fibrous Insulation Materials

ABSTRACT

In this study, we performed a preliminary research on an insulated sandwich structure using high-temperature fibrous insulation materials. Two types of fibrous materials, Saffil alumina and KCC cerakwool insulation materials, were selected. A sandwich specimen was invented to test the heat-shielding performance of the fibrous materials which were sandwiched by an Inconel plate and a titanium plate. The insulated sandwich structure was heated to 800°C for 2,000 seconds. The temperature profiles of the back side of the titanium plate were measured to compare the heat-shielding performance of the fibrous insulation materials. The microstructure of insulation materials, such as the fiber diameter, fiber orientation, and the parent materials of the fiber, was studied to understand how those characteristics influence the radiative properties of the fiber. The difference in microstructural parameters caused a difference in thermal resistance in the fibrous materials. The Saffil alumina insulation had a better performance than KCC cerakwool insulation because of its small fiber diameter and in-plane fiber orientation. The experimental results confirmed the heat transfer simulation results for fibrous materials done by other researchers. In addition, the reusability of high-temperature fibrous insulation, one of the important issues in real applications, was tested.     

Study on functional microcapsules containing catalysts for controlling the curing time and temperature of epoxy resin

In this study, functional microcapsules (FMs) were designed for controlling the curing time and temperature of epoxy through modifications to thermally expandable microcapsules. The FMs were prepared with a mixture of liquid hydrocarbons and N,N-dimethylbenzylamine in the core, and acrylonitrile (AN)—methyl methacrylate copolymer or AN–methacrylate copolymer were used for the shell. Since the FMs were intentionally designed to have thermally vulnerable polymeric shells, the catalyst in the core could be released at the designated temperature. Therefore, FMs do not activate in epoxy at room temperature; rather, the FMs only become functional when the epoxy is cured under a heated atmosphere. Released catalyst at the higher temperature was confirmed by pyrolysis gas chromatography–mass spectrometry and optical microscopy. This study shows that the results will depend on the different compositions of liquid hydrocarbons and catalyst. Particle size of the capsules was changed with different ratio of catalyst and liquid hydrocarbon at the core and type of polymeric shell. Differential scanning calorimetry and rheometer results showed that higher catalyst loading resulted lower in crystalline and shear thickening temperature, respectively. Adhesion strength of epoxy containing FMs was analyzed by lap shear strength in order to detect the void effect due to released gas from the FM. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47499.     

Realization of low-temperature and selective NO2 sensing of SnO2 nanowires via synergistic effects of Pt decoration and Bi2O3 branching

Metal oxide semiconductors with branched structures, such as branched nanowires (b-NWs), have promising properties for being used in gas sensors. In this work, we synthesized Pt-decorated Bi₂O₃-branched SnO₂ nanowires (NWs). NO₂ sensing studies revealed the superior capacity of a Pt-decorated Bi₂O₃-branched SnO₂ NWs gas sensor relative to pristine and branched SnO₂ gas sensors, and it worked at near room temperature (50 °C). The increased sensing capacity was related to the synergistic effects of Pt decoration and Bi₂O₃ branching, particularly the morphology of the gas sensor with branched structures, the promising effects of Pt as a noble metal with good catalytic activity, and the generation of homo- and heterojunctions in the Pt-decorated Bi₂O₃-branched SnO₂ NWs gas sensor. The results obtained in this work are useful for design and development of NO₂ gas sensors using a simple strategy, which can be easily extended to various metal oxides.     

Combining Everolimus and Ku0063794 Promotes Apoptosis of Hepatocellular Carcinoma Cells via Reduced Autophagy Resulting from Diminished Expression of miR-4790-3p

It is challenging to overcome the low response rate of everolimus in the treatment of patients with hepatocellular carcinoma (HCC). To overcome this challenge, we combined everolimus with Ku0063794, the inhibitor of mTORC1 and mTORC2, to achieve higher anticancer effects. However, the precise mechanism for the synergistic effects is not clearly understood yet. To achieve this aim, the miRNAs were selected that showed the most significant variation in expression according to the mono- and combination therapy of everolimus and Ku0063794. Subsequently, the roles of specific miRNAs were determined in the processes of the treatment modalities. Compared to individual monotherapies, the combination therapy significantly reduced viability, increased apoptosis, and reduced autophagy in HepG2 cells. The combination therapy led to significantly lower expression of miR-4790-3p and higher expression of zinc finger protein225 (ZNF225)—the predicted target of miR-4790-3p. The functional study of miR-4790-3p and ZNF225 revealed that regarding autophagy, miR-4790-3p promoted it, while ZNF225 inhibited it. In addition, regarding apoptosis, miR-4790-3p inhibited it, while ZNF225 promoted it. It was also found that HCC tissues were characterized by higher expression of miR-4790-3p and lower expression of ZNF225; HCC tissues were also characterized by higher autophagic flux. We, thus, conclude that the potentiated anticancer effect of the everolimus and Ku0063794 combination therapy is strongly associated with reduced autophagy resulting from diminished expression of miR-4790-3p, as well as higher expression of ZNF225.     

Revisiting “Steady-State” Monotonic and Cyclic Deformation: Emphasizing the Quasi-Stationary State of Deformation

Metallurgical and Materials Transactions A - High-temperature creep, cyclic deformation in saturation, and a number of technologically important processes are typical examples of the so-called...     

Determination of Transfer Patterns of Pectobacterium carotovorum subsp. carotovorum Planktonic Cells and Biofilms During Mechanical Cutting of Kimchi Cabbage

Cross‐contamination of Pectobacterium carotovorum subsp. carotovorum (PCC) from a stainless‐steel surface to cabbage (Brassica rapa L. subsp. pekinensis) was evaluated. To investigate the PCC transfer pattern from mechanical knife surfaces to cabbage during 100 cuts, two mathematical models (power and logarithmic model) were fitted to the mean log₁₀ detection data from cabbage. Overall, regression analysis determined that the best‐fitting regression curves of planktonic cells and detached cells from biofilms transferred onto fresh cabbage were Y = 3.7X^–0.41, RMSE = 0.371 and Y = 4.6X^–0.35, RMSE = 0.254, respectively. For salted cabbage, the best‐fit regression curves of planktonic cells and biofilm were Y = 5.8X^–0.38, RMSE = 0.209 and Y = 5.4X^–0.23, RMSE = 0.195, respectively. Our data provide a meaningful indication of the level of PCC cross‐contamination.     

Low temperature polycrystalline silicon thin film transistor withsilicon nitride ion stopper

The authors have fabricated a new low temperature polycrystalline silicon (poly-Si) thin film transistor (TFT) with silicon nitride (SiN _x) ion-stopper and laser annealed poly-Si. The fabricated poly-Si TFT using SiN_x as the ion-stopper as well as the gate insulator exhibited a field effect mobility of 110 cm²/Vs, subthreshold voltage of 5.5 V, subthreshold slope of 0.48 V/dec., and on/off current ratio of ~10⁶. Low off-state leakage current of 2.4×10^-2 A/μm at the drain voltage of 5 V and the gate voltage of -5 V was achieved