bluuebunny/crossref_metadata_2025 huggingface dataset:
A Reduced-Order Model for the Vibration Analysis of Mistuned Blade–Disc–Shaft Assembly
Authors: Wang Shuai , Bi Chuan-Xing , Zheng Chang-Jun
Published: November 2019

An effective reduced-order model is presented in this paper for the vibration analysis of a mistuned blade–disc–shaft assembly considering the flexibility of the shaft and the rotordynamic effects. For the sake of accurate modeling and quantitative analysis, three-dimensional (3D) finite element models were employed in obtaining the governing equations of motion with the Coriolis force, centrifugal stiffening, and spin softening effects taken into account. Then, an efficient model order reduction technique based on the coordinate projection by normal modes of tuned assembly and cyclic symmetry analysis was developed for mistuned blade–disc–shaft assembly. The criterion of whether one matrix could be incorporated in cyclic symmetry analysis is presented. During the modeling, the mistuning in blade and disc was taken into account and dealt with independently. In mistuning projection, the blade and disc parts were both projected onto their tuned counterparts of the sector model, where the boundary conditions were set to be fixed and free, respectively. Finally, an example of a blade–disc–shaft assembly was employed to validate the effectiveness of the presented method in free and forced vibration analysis.
Siyosapa: At the Edge of Art
Authors: Penney David W.
Published: November 2019

The art history of Native North America built its corpus through considerations of “art-by-appropriation,” referring to selections of historically produced objects reconsidered as art, due to their artful properties, in addition to “art-by-intention,” referring to the work by known artists intended for the art market. The work of Siyosapa, a Hunkpapa/Yanktonai holy man active at Fort Peck, Montana during the 1880s and 1890s, troubles these distinctions with his painted drums and muslin paintings featuring the Sun Dance sold to figures of colonial authority: Military officers, agency officials, and others. This essay reassembles the corpus of his work through the analysis of documentary and collections records. In their unattributed state, some of his creations proved very influential during early attempts by art museums to define American Indian art within a modernist, twentieth century sense of world art history. However, after reestablishing Siyosapa’s agency in the creation and deployment of his drums and paintings, a far more complicated story emerges. While seemly offering “tourist art” or “market art,” his works also resemble diplomatic presentations, and represent material representations of his spiritual powers.
Dust Heterogeneous Reactions during Long-Range Transport of a Severe Dust Storm in May 2017 over East Asia
Authors: Wang Zhe , Uno Itsushi , Yumimoto Keiya , Pan Xiaole , Chen Xueshun , Li Jie , Wang Zifa , Shimizu Atsushi , Sugimoto Nobuo
Published: November 2019

Dust aerosol has important climate and environmental effects, which could be changed by internally mixing with anthropogenic aerosol as a result of heterogeneous reactions; however, the importance of these reactions is not fully understood yet. In this study, synergetic observations and an air quality model were used to analyze the transport of a severe dust storm and its impacts on nitrate and sulfate levels over East Asia between 3 and 11 May 2017. The model successfully reproduced the occurrence and transport of the dust storm compared to dust RGB imageries of the Himawari-8 satellite and dust extinction coefficients observed by LIDAR. The model also reasonably simulated the variations of observed nitrate and sulfate concentrations, and the results indicated that the dust heterogeneous reactions were dominant pathways for nitrate formation, but they had limited contribution for sulfate in both fine and coarse mode in Fukuoka, Japan. Dust nitrate formed rapidly after leaving China, and the highest period-averaged concentration of dust nitrate (>5 μg m−3) was shown over the Yellow Sea. Based on model results; we found that the mass ratio of dust nitrate to dust aerosol could reach 10% over the Pacific Ocean. Our results confirmed the importance of heterogeneous reactions on compositions of dust particles.
The Role of Continental Mesoscale Convective Systems in Forecast Busts within Global Weather Prediction Systems
Authors: Parsons David B. , Lillo Samuel P. , Rattray Christopher P. , Bechtold Peter , Rodwell Mark J. , Bruce Connor M.
Published: November 2019

Despite significant, steady improvements in the skill of medium-range weather prediction systems over the past several decades, the accuracy of these forecasts are occasionally very poor. These forecast failures are referred to as “busts” or “dropouts”. The lack of a clear explanation for bust events limits the development and implementation of strategies designed to reduce their occurrence. This study seeks to explore a flow regime where forecast busts occur over Europe in association with mesoscale convective systems over North America east of the Rocky Mountains. Our investigation focuses on error growth in the European Centre for Medium-Range Weather Forecasting’s (ECMWF’s) global model during the summer 2015 PECAN (Plains Elevated Convection at Night) experiment. Observations suggest that a close, but varied interrelationship can occur between long-lived, propagating, mesoscale convection systems over the Great Plains and Rossby wave packets. Aloft, the initial error occurs in the ridge of the wave and then propagates downstream as an amplifying Rossby wave packet producing poor forecasts in middle latitudes and, in some cases, the Arctic. Our results suggest the importance of improving the representation of organized deep convection in numerical models, particularly for long-lived mesoscale convective systems that produce severe weather and propagate near the jet stream.
Study on Wind Simulations Using Deep Learning Techniques during Typhoons: A Case Study of Northern Taiwan
Authors: Wei Chih-Chiang
Published: November 2019

A scheme for wind-speed simulation during typhoons in Taiwan is highly desirable, considering the effects of the powerful winds accompanying the severe typhoons. The developed combination of deep learning (DL) algorithms with a weather-forecasting numerical model can be used to determine wind speed in a rapid simulation process. Here, the Weather Research and Forecasting (WRF) numerical model was employed as the numerical simulation-based model for precomputing solutions to determine the wind velocity at arbitrary positions where the wind cannot be measured. The deep neural network (DNN) was used for constructing the DL-based wind-velocity simulation model. The experimental area of Northern Taiwan was used for the simulation. Regarding the complex typhoon system, the collected data comprised the typhoon tracks, FNL (Final) Operational Global Analysis Data for the WRF model, typhoon characteristics, and ground weather data. This study included 47 typhoon events that occurred over 2000–2017. Three measures were used to analyze the models for identifying optimal performance levels: Mean absolute error, root mean squared error, and correlation coefficient. This study compared observations with the WRF numerical model and DNN model. The results revealed that (1) simulations by using the WRF-based models were satisfactorily consistent with the observed data and (2) simulations by using the DNN model were considerably consistent with those of the WRF-based model. Consequently, the proposed DNN combined with WRF model can be effectively used in simulations of wind velocity at arbitrary positions of study area.
Lignin Accumulation in Three Pumelo Cultivars in Association with Sucrose and Energy Depletion
Authors: Liu Juan , Huang Qinghua , Kang Peizi , Liang Lei , Chen Junjia
Published: November 2019

Lignification, which occurs in many horticultural fruit and vegetables, brings about undesirable texture and unfavorable consumer preference. However, this problem has rarely been studied. In this work, three pumelo cultivars cvs “Hongroumiyou” (HR), “Bairoumiyou” (BR), and “Huangroumiyou” (HuR) were stored at 25 °C for 90 days, and juice sacs were sampled to explore the lignin accumulation and its relationship to sucrose and energy depletion were investigated. The results displayed that HuR contained lower sucrose content, lower ATP level, but higher lignin content compared to BR and HR during postharvest storage, indicating that the sequence according to storage resistance on the basis of lignin content is as follows: HuR < BR < HR. Furthermore, sucrose degradation attributed to enhanced activities of neutral invertase (NI), soluble acid invertase (S-AI), cell wall-bound invertase (B-AI), and energy deficit on account of declined ATP level, showed significantly negative correlation with lignin accumulation, suggesting that lignin accumulation occurrence could induce sucrose degradation and energy deficit during postharvest storage. Additionally, higher activities of phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO), peroxidase (POD) could accelerate lignin synthesis and resulted in lignin accumulation during postharvest pumelo storage.
Algae: Critical Sources of Very Long-Chain Polyunsaturated Fatty Acids
Authors: Harwood John
Published: November 2019

Polyunsaturated fatty acids (PUFAs), which are divided into n-3 and n-6 classes, are essential for good health in humans and many animals. They are metabolised to lipid mediators, such as eicosanoids, resolvins and protectins. Increasing interest has been paid to the 20 or 22 carbon very long chain PUFAs, since these compounds can be used to form lipid mediators and, thus, avoid inefficient formation of dietary plant PUFAs. The ultimate sources of very long chain PUFAs are algae, which are consumed by fish and then by humans. In this review, I describe the biosynthesis of very long chain PUFAs by algae and how this synthesis can be manipulated for commercial purposes. Ultimately, the production of algal oils is critical for ecosystems worldwide, as well as for human dietary lipids.
Fermented Oyster Extract Promotes Osteoblast Differentiation by Activating the Wnt/β-Catenin Signaling Pathway, Leading to Bone Formation
Authors: Molagoda Ilandarage Menu Neelaka , Karunarathne Wisurumuni Arachchilage Hasitha Maduranga , Choi Yung Hyun , Park Eui Kyun , Jeon You-Jin , Lee Bae-Jin , Kang Chang-Hee , Kim Gi-Young
Published: November 2019

The Pacific oyster, Crassostrea gigas, is well-known as a nutritious food. Recently, we revealed that fermented extract of C. gigas (FO) inhibited ovariectomy-induced osteoporosis, resulting from suppression of osteoclastogenesis. However, since the beneficial effect of FO on osteogenesis is poorly understood, it was examined in mouse preosteoblast MC3T3-E1 cells, human osteosarcoma MG-63 osteoblast-like cells, and zebrafish larvae in this study. We found that FO increased mitochondrial activity from days 1 to 7; however, total cell number of MC3T3-E1 cells gradually decreased without any change in cell viability, which suggests that FO stimulates the differentiation of MC3T3-E1 cells. FO also promoted the expression of osteoblast marker genes, including runt-related transcription factor 2 (mRUNX2), alkaline phosphatase (mALP), collagen type I α1 (mCol1α1), osteocalcin (mOCN), osterix (mOSX), bone morphogenetic protein 2 (mBMP2), and mBMP4 in MC3T3-E1 cells accompanied by a significant increase in ALP activity. FO also increased nuclear translocation of RUNX2 and OSX transcription factors, ALP activity, and calcification in vitro along with the upregulated expression of osteoblast-specific marker proteins such as RUNX2, ALP, Col1α1, OCN, OSX, and BMP4. Additionally, FO enhanced bone mineralization (calcein intensity) in zebrafish larvae at 9 days post-fertilization comparable to that in the β-glycerophosphate (GP)-treated group. All the tested osteoblast marker genes, including zRUNX2a, zRUNX2b, zALP, zCol1a1, zOCN, zBMP2, and zBMP4, were also remarkably upregulated in the zebrafish larvae in response to FO. It also promoted tail fin regeneration in adult zebrafish as same as the GP-treated groups. Furthermore, not only FO positively regulate β-catenin expression and Wnt/β-catenin luciferase activity, but pretreatment with a Wnt/β-catenin inhibitor (FH535) also significantly decreased FO-mediated bone mineralization in zebrafish larvae, which indicates that FO-induced osteogenesis depends on the Wnt/β-catenin pathway. Altogether, the current study suggests that the supplemental intake of FO has a beneficial effect on osteogenesis.
Knockout of Arabidopsis Serotonin N-Acetyltransferase-2 Reduces Melatonin Levels and Delays Flowering
Authors: Lee Hyoung Yool , Lee Kyungjin , Back Kyoungwhan
Published: November 2019

Melatonin plays roles in both plant growth and defense. Serotonin N-acetyltransferase (SNAT) catalyzes formation of N-acetylserotonin (NAS) from serotonin. Plants contain two SNAT isogenes, which exhibit low-level amino acid homology. We studied the Arabidopsis thaliana SNAT2 (AtSNAT2) gene; we prepared recombinant SNAT2 protein and characterized a snat2 knockout mutant. The SNAT2 protein exhibited 27% amino acid homology with SNAT1; the Km was 232 μM and the Vmax was 2160 pmol/min/mg protein. Melatonin inhibited SNAT enzyme activity in vitro. SNAT2 mRNA was abundantly expressed in flowers; the melatonin content of flowers of the snat2 mutant was significantly less than that of wild-type flowers. The mutant exhibited delayed flowering and reductions in leaf area and biomass compared to the wild type. Delayed flowering was attributable to reductions in the expression levels of the gibberellin biosynthetic genes ent-kaurene synthase (KS) and FLOWERING LOCUS T (FT).
Ectopic Expression of Glycine max GmNAC109 Enhances Drought Tolerance and ABA Sensitivity in Arabidopsis
Authors: Nguyen Nguyen Cao , Hoang Xuan Lan Thi , Nguyen Quang Thien , Binh Ngo Xuan , Watanabe Yasuko , Thao Nguyen Phuong , Tran Lam-Son Phan
Published: November 2019

The NAC (NAM, ATAF1/2, CUC2) transcription factors are widely known for their various functions in plant development and stress tolerance. Previous studies have demonstrated that genetic engineering can be applied to enhance drought tolerance via overexpression/ectopic expression of NAC genes. In the present study, the dehydration- and drought-inducible GmNAC109 from Glycine max was ectopically expressed in Arabidopsis (GmNAC109-EX) plants to study its biological functions in mediating plant adaptation to water deficit conditions. Results revealed an improved drought tolerance in the transgenic plants, which displayed greater recovery rates by 20% to 54% than did the wild-type plants. In support of this finding, GmNAC109-EX plants exhibited lower water loss rates and decreased endogenous hydrogen peroxide production in leaf tissues under drought, as well as higher sensitivity to exogenous abscisic acid (ABA) treatment at germination and early seedling development stages. In addition, analyses of antioxidant enzymes indicated that GmNAC109-EX plants possessed stronger activities of superoxide dismutase and catalase under drought stress. These results together demonstrated that GmNAC109 acts as a positive transcriptional regulator in the ABA-signaling pathway, enabling plants to cope with adverse water deficit conditions.
Development and Mechanistic Insight into the Enhanced Cytotoxic Potential of Parvifloron D Albumin Nanoparticles in EGFR-Overexpressing Pancreatic Cancer Cells
Authors: Santos-Rebelo Ana , Kumar Pradeep , Pillay Viness , Choonara Yahya E. , Eleutério Carla , Figueira Mariana , Viana Ana S. , Ascensão Lia , Molpeceres Jesús , Rijo Patrícia , Correia Isabel , Amaral Joana , Solá Susana , Rodrigues Cecília M. P. , Gaspar Maria Manuela , Reis Catarina Pinto
Published: November 2019

Pancreatic cancer is one of the most lethal cancers, with an extremely poor prognosis. The development of more effective therapies is thus imperative. Natural origin compounds isolated from Plectranthus genus, such as parvifloron D (PvD), have cytotoxic and antiproliferative activity against human tumour cells. However, PvD is a very low water-soluble compound, being nanotechnology a promising alternative strategy to solve this problem. Therefore, the aim of this study was to optimize a nanosystem for preferential delivery of PvD to pancreatic tumour cells. Albumin nanoparticles (BSA NPs) were produced through a desolvation method. Glucose cross-linking and bioactive functionalization profiles of BSA platform were elucidated and analysed using static lattice atomistic simulations in vacuum. Using the optimized methodology, PvD was encapsulated (yield higher than 80%) while NPs were characterized in terms of size (100–400 nm) and morphology. Importantly, to achieve a preferential targeting to pancreatic cancer cells, erlotinib and cetuximab were attached to the PvD-loaded nanoparticle surface, and their antiproliferative effects were evaluated in BxPC3 and Panc-1 cell lines. Erlotinib conjugated NPs presented the highest antiproliferative effect toward pancreatic tumour cells. Accordingly, cell cycle analysis of the BxPC3 cell line showed marked accumulation of tumour cells in G1-phase and cell cycle arrest promoted by NPs. As a result, erlotinib conjugated PvD-loaded BSA NPs must be considered a suitable and promising carrier to deliver PvD at the tumour site, improving the treatment of pancreatic cancer.
Lenalidomide Maintenance with or without Prednisone in Newly Diagnosed Myeloma Patients: A Pooled Analysis
Authors: Bonello Francesca , Pulini Stefano , Ballanti Stelvio , Gentile Massimo , Spada Stefano , Annibali Ombretta , Omedé Paola , Ronconi Sonia , Cangialosi Clotilde , Podda Luigi , Palmas Angelo , Malfitano Alessandra , Rivoli Giulia , Belotti Angelo , Ciambelli Fabrizio , Vincelli Iolanda Donatella , Cafro Anna Maria , Innao Vanessa , Palumbo Antonio , Sonneveld Pieter , Spencer Andrew , Hájek Roman , Boccadoro Mario , Gay Francesca
Published: November 2019

We conducted a pooled analysis of two phase III trials, RV-MM-EMN-441 and EMN01, to compare maintenance with lenalidomide-prednisone vs. lenalidomide in newly diagnosed transplant-eligible and -ineligible myeloma patients. Primary endpoints were progression-free survival, progression-free survival 2 and overall survival with both regimens. A secondary aim was to evaluate the impact of duration of maintenance on overall survival and on outcome after relapse. A total of 625 patients (lenalidomide-prednisone arm, n = 315; lenalidomide arm, n = 310) were analyzed. The median follow-up was 58 months. Median progression-free survival (25 vs. 19 months; p = 0.08), progression-free survival 2 (56 vs. 49 months; p = 0.9) and overall survival (73 months vs. NR; p = 0.08) were not significantly different between the two arms. Toxicity profiles of lenalidomide-prednisone and lenalidomide were similar, with the exception of neutropenia that was higher in the lenalidomide arm (grade ≥ 3: 9% vs. 19%, p < 0.001), without an increase in the rate of infections. Overall survival (median NR vs. 49 months, p < 0.001), progression-free survival from relapse (median 35 vs. 24 months, p = 0.004) and overall survival from relapse (median not reached vs. 41 months, p = 0.002) were significantly longer in patients continuing maintenance for ≥2 years. We showed that the addition of prednisone at 25 or 50 mg every other day (eod) to lenalidomide maintenance did not induce any significant advantage.
ADAM17 Activity and IL-6 Trans-Signaling in Inflammation and Cancer
Authors: Schumacher Neele , Rose-John Stefan
Published: November 2019

All ligands of the epidermal growth factor receptor (EGF-R) are transmembrane proteins, which need to be proteolytically cleaved in order to be systemically active. The major protease responsible for this cleavage is the membrane metalloprotease ADAM17, which also has been implicated in cleavage of TNFα and interleukin-6 (IL-6) receptor. It has been recently shown that in the absence of ADAM17, the main protease for EGF-R ligand processing, colon cancer formation is largely abrogated. Intriguingly, colon cancer formation depends on EGF-R activity on myeloid cells rather than on intestinal epithelial cells. A major activity of EGF-R on myeloid cells is the stimulation of IL-6 synthesis. Subsequently, IL-6 together with the ADAM17 shed soluble IL-6 receptor acts on intestinal epithelial cells via IL-6 trans-signaling to induce colon cancer formation, which can be blocked by the inhibitor of IL-6 trans-signaling, sgp130Fc. Blockade of IL-6 trans-signaling therefore offers a new therapeutic window downstream of the EGF-R for the treatment of colon cancer and possibly of other EGF-R related neoplastic diseases.
Ti3+ Defective SnS2/TiO2 Heterojunction Photocatalyst for Visible-Light Driven Reduction of CO2 to CO with High Selectivity
Authors: Han Aiguo , Li Mei , Zhang Shengbo , Zhu Xinli , Han Jinyu , Ge Qingfeng , Wang Hua
Published: November 2019

In recent years, defective TiO2-based composite nanomaterials have received much attention in the field of photocatalysis. In this work, TiB2 was used as a precursor to successfully prepare Ti3+ defective TiO2 (TiO2-B) with a truncated bipyramidal structure by a one-step method. Then, the SnS2 nanosheets were assembled onto the as-prepared TiO2-B through simple hydrothermal reaction. TiO2-B exhibits strong visible light absorption properties, but the recombination rate of the photo-generated electron-hole pair was high and does not exhibit ideal photocatalytic performance. Upon introducing SnS2, the heterojunction catalyst SnS2-Ti3+ defective TiO2 (SnS2/TiO2-B) not only possesses the strong light absorption from UV to visible light region, the lowest photo-generated charge recombination rate but also achieves a more negative conduction band potential than the reduction potential of CO2 to CO, and thereby, exhibits the significantly enhanced selectivity and yield of CO in photocatalytic CO2 reduction. Notably, SnS2/TiO2-B produces CO at a rate of 58 µmol·h−1·g−1 with CO selectivity of 96.3% under visible light irradiation, which is 2 and 19 times greater than those of alone TiO2-B and SnS2, respectively. Finally, a plausible photocatalytic mechanism on SnS2/TiO2-B was proposed that the electron transfer between TiO2 and SnS2 follows the Z-scheme mode. Our results present an effective way to gain highly efficient TiO2 based photocatalysts for CO2 reduction by combining different modification methods of TiO2 and make full use of the synergistic effects.
Estimation of the Effectiveness Factor for Immobilized Enzyme Catalysts through a Simple Conversion Assay
Authors: Valencia Pedro , Ibañez Francisco
Published: November 2019

A novel methodology to estimate the effectiveness factor (EF) of an immobilized enzyme catalyst is proposed here. The methodology consists of the determination of the productivity of both the immobilized enzyme catalyst and its corresponding soluble enzyme, plotted as a function of the reaction conversion. The ratio of these productivities corresponds to the EF estimator of the catalyst. Conversion curves were simulated in a batch reactor with immobilized enzyme and soluble enzyme for different values of the S0/KM ratio and Thiele modulus (Φ) to demonstrate this hypothesis. Two different reaction orders were tested: first-order kinetic and Michaelis–Menten-based kinetic with product inhibition. The results showed that the ratio of productivities between the immobilized and soluble enzymes followed the behavior profile presented by the EF with satisfactory agreement. This simple methodology to estimate the EF is based on routine conversion experiments, thus avoiding the exhaustive kinetic and mass transfer characterization of the immobilized enzyme catalyst.
Wnt Signalling in Acute Myeloid Leukaemia
Authors: Gruszka Alicja M. , Valli Debora , Alcalay Myriam
Published: November 2019

Acute myeloid leukaemia (AML) is a group of malignant diseases of the haematopoietic system. AML occurs as the result of mutations in haematopoietic stem/progenitor cells, which upregulate Wnt signalling through a variety of mechanisms. Other mechanisms of Wnt activation in AML have been described such as Wnt antagonist inactivation through promoter methylation. Wnt signalling is necessary for the maintenance of leukaemic stem cells. Several molecules involved in or modulating Wnt signalling have a prognostic value in AML. These include: β-catenin, LEF-1, phosphorylated-GSK3β, PSMD2, PPARD, XPNPEP, sFRP2, RUNX1, AXIN2, PCDH17, CXXC5, LLGL1 and PTK7. Targeting Wnt signalling for tumour eradication is an approach that is being explored in haematological and solid tumours. A number of preclinical studies confirms its feasibility, albeit, so far no reliable clinical trial data are available to prove its utility and efficacy.
A New Assistant Method for Characterizing Ablation Resistance of ZrC-SiC Dispersive Biphasic Coating on C/C Composites
Authors: Feng Tao , Tong Mingde , Yao Shuotian , Wen Shifeng
Published: November 2019

To optimize the ablation resistance of ZrC coating, ZrC-SiC dispersive biphasic coating was prepared by chemical vapor co-deposition. The ablation resistances of the coatings were carried out by oxyacetylene flame tests. Compared with double-layered ZrC/SiC coating, the ablation resistance of ZrC-SiC coating was evaluated. On the basis of similar mass ablation rates of the two coatings, a new assistant method for characterizing the thermal protecting effect of coatings on carbon-carbon composites (C/C) composites was proposed. The thermal protecting ability of the coating was accurately reflected by the changes of hardness and elastic modulus of C/C substrate below the central region of ablated coatings before and after ablation. The ablation processes of two kinds of coatings were also discussed. The results showed that the hardness and elastic modulus of the C/C substrate protected by ZrC-SiC coating were higher than that of C/C coated with ZrC/SiC coating. The result convincingly illustrated the thermal protecting ability of ZrC-SiC coating was much better than that of ZrC/SiC coating, which attributed to the formation of Zr-Si-O glass.
Preparation of Intumescent Fire Protective Coating for Fire Rated Timber Door
Authors: Kwang Yin Jessica Jong , Yew Ming Chian , Yew Ming Kun , Saw Lip Huat
Published: November 2019

Intumescent flame-retardant coating (IFRC) provides a protective barrier to heat and mass transfer for the most efficient utilization of a wide variety of passive fire protection systems at the recent development. This article highlights the fire-resistance, physical, chemical, mechanical, and thermal properties of the IFRC using a Bunsen burner, furnace, Scanning Electron Microscope, freeze-thaw stability test, Instron Micro Tester, and thermogravimetric analysis (TGA) test. The five IFRC formulations were mixed with vermiculite and perlite for the fabrication of fire-resistant timber door prototypes in this research project. Additionally, the best fire-resistance performance of the fire-rated door prototype was selected and compared with a commercial prototype under the fire endurance test. An inventive fire-rated door prototype (P2), with a low density of 636.45 kg/m3, showed an outstanding fire-resistance rating performance, resulting in temperature reduction by up to 54.9 °C, as compared with that of the commercial prototype. Significantly, a novel fire-rated timber door prototype with the addition of formulating intumescent coating has proven to be efficient in preventing fires and maintaining its integrity by surviving a fire resistance period of 2 h.
Naked Metal Cations Swimming in Protein Crystals
Authors: Djinović-Carugo Kristina , Carugo Oliviero
Published: November 2019

The presence of isolated metal cations, far from any other atom, is not uncommon in protein crystal structures. A systematic survey of the Protein Data Bank showed that nearly 8% of the metal cations are naked, more frequently if they can interact only electrostatically with their neighbors. Surprisingly, this seemed to be only weakly related to the crystallographic resolution.
Imaging Features of Multiple Myeloma Extramedullary Lesions in the Liver with 18F-FDG PET/CT, Contrast-Enhanced CT and MRI
Authors: Papamichail Dimitris , Hog Robert , Goldschmidt Hartmut , Dimitrakopoulou-Strauss Antonia
Published: November 2019

Ηepatic involvement in multiple myeloma is not common; nevertheless, it is associated with poorer outcome. Heterogeneous features have been described in few published reports so far. We present the imaging findings of PET/CT in comparison to those of MRI for two multiple myeloma (MM) patients, one with a liver lesion suspicious for myeloma metastasis on PET and one with multiple liver lesions suspicious for myeloma metastases on MRΙ. The subsequent ultrasound-guided needle biopsies confirmed the extramedullary spread of the disease in both patients. The first case exhibited a match in both functional imaging modalities (PET and MRI) but a mismatch of intense metabolic activity on 18F-fluorodeoxyglucose (18F-FDG) PET/CT and iso-attenuating liver parenchyma on contrast-enhanced CT. The second case showed a mismatch of signal elevation persistence on diffusion-weighted imaging (DWI) and physiologic 18F-FDG distribution in the liver parenchyma. These cases present different imaging features in MM lesions of the liver using PET/CT and MRI, reflecting the high disease heterogeneity in patients with MM and demonstrating that the use of both PET/CT and MRI may offer complementary information.
Role of Heat Expansion with a Series of Ionic Liquids: The Case for Isochoric Thermoelectric Generators and Minimal Steric Repulsion
Authors: Jackson Marcus , Engel Robert , Vuong Luat
Published: November 2019

The role of convection in liquid thermoelectric cells may be difficult to predict because the inter- and intramolecular interactions are not currently incorporated into thermodynamic models. Here, we study the thermoelectric response of a series of five anhydrous 1-methyl-3- alkylimidazolium halide ionic liquids with varied chain length and counterion in a high-aspect-ratio, horizontal-temperature-gradient geometry, where convection is minimal. While a canonical constant-volume thermodynamic model predicts that the longer aliphatic groups exhibit larger Seebeck coefficients, we instead measure the opposite: Longer aliphatic chains correlate with lower densities and greater heat expansion, stronger intermolecular associations, stronger steric repulsion, and lower Seebeck coefficients. As evidence of the critical role of thermal expansion, we measure that the Seebeck effect is nonlinear: Values of −2.8 mV/K with a 10 K temperature difference and −1.8 mV/K with a 50 K difference are measured with ether ion. Our results indicate that steric repulsion and heat expansion are important considerations in ionic liquid design; with large temperature differences, the Seebeck coefficient correlates negatively with heat expansion. Our results suggest that Seebeck values will improve if thermal expansion is limited in a pressurized, isochoric, convection-free design.
Kappa Distributions and Isotropic Turbulence
Authors: Gravanis Elias , Akylas Evangelos , Panagiotou Constantinos , Livadiotis George
Published: November 2019

In this work, the two-point probability density function (PDF) for the velocity field of isotropic turbulence is modeled using the kappa distribution and the concept of superstatistics. The PDF consists of a symmetric and an anti-symmetric part, whose symmetry properties follow from the reflection symmetry of isotropic turbulence, and the associated non-trivial conditions are established. The symmetric part is modeled by the kappa distribution. The anti-symmetric part, constructed in the context of superstatistics, is a novel function whose simplest form (called “the minimal model”) is solely dictated by the symmetry conditions. We obtain that the ensemble of eddies of size up to a given length r has a temperature parameter given by the second order structure function and a kappa-index related to the second and the third order structure functions. The latter relationship depends on the inverse temperature parameter (gamma) distribution of the superstatistics and it is not specific to the minimal model. Comparison with data from direct numerical simulations (DNS) of turbulence shows that our model is applicable within the dissipation subrange of scales. Also, the derived PDF of the velocity gradient shows excellent agreement with the DNS in six orders of magnitude. Future developments, in the context of superstatistics, are also discussed.
Take-Home Exams in Higher Education: A Systematic Review
Authors: Bengtsson Lars
Published: November 2019

This work describes a systematic review of the research on take-home exams in tertiary education. It was found that there is some disagreement in the community about the virtues of take-home exams but also a lot of agreement. It is concluded that take-home exams may be the preferred choice of assessment method on the higher taxonomy levels because they promote higher-order thinking skills and allow time for reflection. They are also more consonant with constructive alignment theories and turn the assessment into a learning activity. Due to the obvious risk of unethical student behavior, take-home exams are not recommended on the lowest taxonomy level. It is concluded that there is still a lot of research missing concerning take-home exams in higher education and some of this research may be urgent due to the emergence of massive online open courses (MOOCs) and online universities where non-proctored exams prevail.
Current Source AC-Side Clamped Inverter for Leakage Current Reduction in Grid-Connected PV System
Authors: Li Xiangli , Wang Na , San Guocheng , Guo Xiaoqiang
Published: November 2019

For the grid-connected photovoltaic inverters, the switching-frequency common-mode voltage brings the leakage current, which should be eliminated. So far, many kinds of single-phase inverters have been published for this purpose, but most of them are the conventional voltage-type ones, which have the disadvantages of poor reliability due to the DC-link electrolytic capacitor and the risk of short-through of the bridge switches. To solve this technical issue, a novel current source inverter with AC-side clamping is proposed to mitigate the switching-frequency common-mode voltage. Meanwhile, a novel modulation method is proposed for the new single-phase inverter to achieve low-frequency operation of the main switches, which reduces the switching losses. Finally, the proposed method is implemented on the TMS320F28335DSP + XC6SLX9FPGA digital hardware platform. Also, the performance comparisons are done with the traditional solution. The results prove the proposed solution.
Downlink Power Allocation Strategy for Next-Generation Underwater Acoustic Communications Networks
Authors: Ahmad Ishtiaq , Chang KyungHi
Published: November 2019

The increasing interest in next-generation underwater acoustic communications networks is due to vast investigation of oceans for oceanography, commercial operations in maritime areas, military surveillance, and more. A surface buoy or underwater base station controller (UBSC) communicates with either transceivers or underwater base stations (UBSs) via acoustic links. Transceivers further communicate with underwater sensor nodes using acoustic links. In this paper, we employ a downlink (DL) power allocation (PA) strategy using an orthogonal frequency-division multiple access (OFDMA) technique for underwater acoustic communications (UAC) networks. First, we present an approach to power offsets using three kinds of pilot spacing and apply the power boosting (PB) concept on orthogonal frequency-division multiplexing (OFDM) symbols for the UAC network. Secondly, we draw the block error rate (BLER) curves from link-level simulation (LLS) and analyze the signal-to-noise ratio (SNR) for both PA and non-PA strategies. Lastly, we adopt the best PB for system-level simulation (SLS) and compare the throughput and outage performance for PA and non-PA strategies. Hence, the simulation results confirm the effectiveness of the DL PA strategy for UAC networks.
Unstable System Control Using an Improved Particle Swarm Optimization-Based Neural Network Controller
Authors: Lin Cheng-Jian , Lin Xin-You , Jhang Jyun-Yu
Published: November 2019

In this study, an improved particle swarm optimization (IPSO)-based neural network controller (NNC) is proposed for solving a real unstable control problem. The proposed IPSO automatically determines an NNC structure by a hierarchical approach and optimizes the parameters of the NNC by chaos particle swarm optimization. The proposed NNC based on an IPSO learning algorithm is used for controlling a practical planetary train-type inverted pendulum system. Experimental results show that the robustness and effectiveness of the proposed NNC based on IPSO are superior to those of other methods.
Techno-Economic Analysis of a Novel Two-Stage Flashing Process for Acid Gas Removal from Natural Gas
Authors: Dai Yiyang , Peng Yuwei , Qiu Yi , Liu Huimin
Published: November 2019

Excessive CO2 content will reduce the natural gas calorific value and increase the energy consumption of the regenerator in natural gas desulfurization and decarbonization. This paper uses Aspen HYSYS to model a novel two-stage flash process of acid gas removal process from natural gas. According to the results from the simulation, as well as running experiences in a natural gas processing plant in the middle east, it can be demonstrated that this new process, which has been used in the field of natural gas desulfurization and decarbonization, can meet the requirement of product specifications. Based on the steady state simulation, Aspen HYSYS sensitivity function is used to evaluate influence of key operating parameters, such as the second flash pressure and temperature, on the energy consumption. Compared to the traditional acid gas removal process and acid gas enrichment process, the new two-stage flash acid gas removal process has less energy consumption (2.2 × 109 kJ·h−1). In addition, two-stage flash acid gas removal process also improves the efficiency of acid gas enrichment, while the overall energy consumption is less than combination process of traditional process and acid gas enrichment process.
Analysis on the Force and Life of Gearbox in Double-Rotor Wind Turbine
Authors: Yang Yaru , Li Hua , Yao Jin , Gao Wenxiang , Peng Haiyan
Published: November 2019

In order to study the force and life of the key components in the gearbox of an existing double-rotor wind turbine, the design and structural parameters of the gearbox in the traditional National Renewable Energy Laboratory (NREL) 5 MW single-rotor wind turbine are adopted, and the fixed ring gear of the first planetary stage transmission is released to form a differential gearbox suitable for a double-rotor wind turbine with two inputs. The double input is used to connect the double rotor. Subsequently, the characteristics of the gearbox in a double-rotor wind turbine are discussed. On the basis of the constant rated power of the whole wind turbine, the total power is divided into two parts, which are allocated to the double rotors, then two rotational speeds of the two inputs are given according to different power ratios by complying with the matching principle of force and moment. Furthermore, the force acting on the pitch circle of the planet gear, as well as the force and life of the planet bearing of the two-stage planetary transmission are calculated and compared with a single-rotor wind turbine. The results show that the structural advantages of a double-rotor wind turbine can reduce the stress of key components of the gearbox and increase the life span of the planet bearing, thereby the life of the whole gearbox is improved and the downtime of the whole wind turbine is reduced.
Simplified Method for Analyzing the Availability of Rooftop Photovoltaic Potential
Authors: Mavsar Primož , Sredenšek Klemen , Štumberger Bojan , Hadžiselimović Miralem , Seme Sebastijan
Published: November 2019

This paper presents a new simplified method for analyzing the availability of photovoltaic potential on roofs. Photovoltaic systems on roofs are widespread as they represent a sustainable and safe investment and, therefore, a means of energy self-sufficiency. With the growth of photovoltaic systems, it is also crucial to correctly evaluate their global efficiency. Thus, this paper presents a comparison between known methods for estimating the photovoltaic potential (as physical, geographic and technical contributions) on a roof and proposes a new simplified method, that takes into account the economic potential of a building that already has installed a photovoltaic system. The measured values of generated electricity of the photovoltaic system were compared with calculated photovoltaic potential. In general, the annual physical, geographic, technical and economic potentials were 1273.7, 1253.8, 14.2 MWh, and 279.1 Wh, respectively. The analysis of all four potentials is essential for further understanding of the sustainable and safe investment in photovoltaic systems.
Mobilized Mohr-Coulomb and Hoek-Brown Strength Parameters during Failure of Granite in Alxa Area in China for High-Level Radioactive Waste Disposal
Authors: Cheng Cheng , Xu Nengxiong , Zheng Bo
Published: November 2019

Strength parameters of the host rock is of paramount importance for modelling the behaviors of underground disposal repository of high-level radioactive waste (HLW). Mobilization of strength parameters should be studied for a better understanding and modelling on the mechanical behaviors of the surrounding rock, considering the effect of temperature induced by the nuclear waste. The granite samples cored from NRG01 borehole in Alxa candidate area in China for HLW disposal are treated by different temperatures (T = 20 °C, 100 °C and 200 °C), and then are used to carry out a series of uniaxial and tri-axial compression experiments under various confining pressures (σ3 = 0, 5, 10, 20, and 30 MPa) in this study. With the recorded axial stress—axial strain and axial stress—lateral strain curves, mobilization of both Mohr-Coulomb and Hoek-Brown strength parameters are analyzed with the increasing plastic shear strain. It has been found that NRG01 granite samples show generally similar cohesion weakening and friction strengthening behaviors, as well as the non-simultaneous mobilization of Hoek-Brown strength parameters ( m b and s ), under the effect of various treatment temperatures. Furthermore, the samples treated by higher temperatures show lower initial values of cohesion, but their initial friction angle and m b values are relatively higher. This should be mainly owing to the thermally induced cracks in the samples. This study should be helpful for a better modelling on the mechanical behaviors of NRG01 granite samples as the host rock of a possible HLW disposal repository.
Numerical Study of Highly Viscous Fluid Sloshing in the Real-Scale Membrane-Type Tank
Authors: Mi Shuo , Huang Zongliu , Jin Xin , Tabatabaei Malazi Mahdi , Liu Mingming
Published: November 2019

The highly viscous liquid (glycerin) sloshing is investigated numerically in this study. The full-scale membrane-type tank is considered. The numerical investigation is performed by applying a two-phase numerical model based on the spatially averaged Navier-Stokes equations. Firstly, the numerical model is validated against the available numerical model and a self-conducted experiment then is applied to systematically investigate the full-scale sloshing. In this study, two filling levels (50% and 70% of the tank height) are considered. The fluid kinematic viscosity is fixed at a value being 6.0 × 10−5 m2/s with comparative value to that of the crude oil. A wide range of forcing periods varying from 8.0 s to 12.0 s are used to identify the response process of pressures as well as free surface displacements. The pressures are analyzed along with breaking free surface snapshots and corresponding pressure distributions. The slamming effects are also demonstrated. Finally, the frequency response is further identified by the fast Fourier transformation technology.
Markov Chain Simulation of Coal Ash Melting Point and Stochastic Optimization of Operation Temperature for Entrained Flow Coal Gasification
Authors: Zhang Jinchun , Guan Shiheng , Hou Jinxiu , Zhang Zichuan , Li Zhaoqian , Meng Xiangzhong , Wang Chao
Published: November 2019

In the entrained flow coal gasification process, the gas production is critically affected by the operating temperature (OT) and coal ash melting point (AMP), and the AMP is one of key factors for the determinations of OT. Considering the fact that coal is a typical nonhomogeneous substance and the coal ash composition varies from batch to batch, this paper proposes the application of the Markov Chain (MC) method in simulation of the random AMP series and the stochastic optimization of OT based on MC simulation for entrained flow coal gasification. The purpose of this paper is to provide a more accurate optimal OT decision method for entrained flow coal gasification practice. In this paper, the AMP was regarded as a random variable, and the random process method, Markov Chain, was used to describe the random AMP series of feed coal. Firstly, the MC simulation model about AMP was founded according to an actual sample data, 200 sets of AMP data from an industrial gasification plant under three simulation schemes (the sample data were individually divided into 16, eight and four state groups,). The comparisons between the simulation results and the actual values show that the founded MC simulation model descries the AMP series very well. Then, a stochastic programming model based on MC simulation for OT optimization was developed. Finally, this stochastic programming optimization model was optimized by genetic algorithm (GA). Comparing with the conventional OT optimization method, the proposed stochastic OT optimization model integrated MC simulation can ascertain a more accurate OT for guiding the coal gasification practice.
Effect of Water Vapor Injection on the Distributions of Equivalence Ratio and the NO Emission Reduction in a CI Engine
Authors: Min Se Hun , Suh Hyun Kyu
Published: November 2019

The objective of this study was to investigate the influence of a water vapor injection into the intake port of a small compression ignition engine and analyze the effect of the collisions between the water particles and the injected fuel on combustion and exhaust emission performances. To simulate the water vapor by the ultrasonic humidifier in the numerical analysis, the water particles were introduced into the cylinder through an intake port during the intake process, and the amount was varied from 10% to 30% of the injected fuel mass per stroke. When the water vapor was injected into the intake port, the rich equivalence ratio region was distributed in the center of cylinder. In addition, the ISNO (indicated specific nitrogen oxide) values decreased up to 46% more than the values for the condition without the water-vapor-injection. However, the ISSoot (indicated specific soot) exhibited similar values in any conditions. For starts of energizing timing that were BTDC (before top dead center) 25 deg and 15 deg, the ISFC (indicated fuel consumption) values decreased with increased portions of water vapor. However, in the case of BTDC 05deg, the ignition delay was too long, which deteriorated combustion performance.