bluuebunny/crossref_metadata_2025 huggingface dataset:
Delayed Chromosome Alignment to the Spindle Equator Increases the Rate of Chromosome Missegregation in Cancer Cell Lines
Authors: Kuniyasu Kinue , Iemura Kenji , Tanaka Kozo
Published: December 2018

For appropriate chromosome segregation, kinetochores on sister chromatids have to attach to microtubules from opposite spindle poles (bi-orientation). Chromosome alignment at the spindle equator, referred to as congression, can occur through the attachment of kinetochores to the lateral surface of spindle microtubules, facilitating bi-orientation establishment. However, the contribution of this phenomenon to mitotic fidelity has not been clarified yet. Here, we addressed whether delayed chromosome alignment to the spindle equator increases the rate of chromosome missegregation. Cancer cell lines depleted of Kid, a chromokinesin involved in chromosome congression, showed chromosome alignment with a slight delay, and increased frequency of lagging chromosomes. Delayed chromosome alignment concomitant with an increased rate of lagging chromosomes was also seen in cells depleted of kinesin family member 4A (KIF4A), another chromokinesin. Cells that underwent chromosome missegregation took relatively longer time to align chromosomes in both control and Kid/KIF4A-depleted cells. Tracking of late-aligning chromosomes showed that they exhibit a higher rate of lagging chromosomes. Intriguingly, the metaphase of cells that underwent chromosome missegregation was shortened, and delaying anaphase onset ameliorated the increased chromosome missegregation. These data suggest that late-aligning chromosomes do not have sufficient time to establish bi-orientation, leading to chromosome missegregation. Our data imply that delayed chromosome alignment is not only a consequence, but also a cause of defective bi-orientation establishment, which can lead to chromosomal instability in cells without severe mitotic defects.
Erythropoietin Protects Against Cognitive Impairment and Hippocampal Neurodegeneration in Diabetic Mice
Authors: Othman Manal A. M. , Rajab Ebrahim , AlMubarak Ahmed , AlNaisar Mohammed , Bahzad Noora , Kamal Amer
Published: December 2018

Administration of erythropoietin (EPO) is neuroprotective against a variety of experimentally-induced neurological disorders. The aim was to determine if EPO protects against hippocampal neurodegeneration as well as impairment of cognition and motor performance, associated with long-term diabetes. BALB/c mice were randomly allocated between control, diabetic and EPO-treated diabetic groups. EPO-treated diabetic mice were administered EPO 0.05 U/kg/day i.p. three times/week for 10 weeks. Cognition was assessed by Morris water maze. Brain samples were processed for light microscopic evaluation of hippocampus. Controls showed gradual improvement of cognitive performance in water maze when comparing latency (p < 0.01) and distance swum to reach the platform (p = 0.001). There was a similar trend for improvement in EPO-treated diabetics (p < 0.001). Latency did not improve in diabetic animals indicating lack of learning (p = 0.79). In probe trials, controls and EPO-treated diabetics spent more time in the training quadrant than expected by chance (p < 0.001). Diabetics did not show memory recall behavior; performance was significantly worse than expected by chance (p = 0.023). In diabetics, there was neurodegeneration in hippocampus and reduction in number of granule cells (p < 0.01) in the dentate gyrus. EPO treatment improved these neurodegenerative changes and preserved numbers of granule cells (p < 0.1, compared to controls). Erythropoietin treatment is protective against cognitive deficits and hippocampal neurodegeneration in diabetic mice.
Carbon-Based Magnetic Nanocarrier for Controlled Drug Release: A Green Synthesis Approach
Authors: Oliveira Jessica R. P. , Rodrigues Raquel O. , Barros Lillian , Ferreira Isabel C. F. R. , Marchesi Luís F. , Koneracka Martina , Jurikova Alena , Zavisova Vlasta , Gomes Helder T.
Published: December 2018

In this study, hydrophilic magnetic nanoparticles were synthesized by green routes using a methanolic extract of Rubus ulmifolius Schott flowers. The prepared magnetic nanoparticles were coated with carbon-based shell for drug delivery application. The nanocomposites were further chemically functionalized with nitric acid and, sequentially, with Pluronic® F68 (CMNPs-plur) to enhance their colloidal stability. The resulting material was dispersed in phosphate buffer solution at pH 7.4 to study the Doxorubicin loading. After shaking for 48 h, 99.13% of the drug was loaded by the nanocomposites. Subsequently, the drug release was studied in different working phosphate buffer solutions (i.e., PB pH 4.5, pH 6.0 and pH 7.4) to determine the efficiency of the synthesized material for drug delivery as pH-dependent drug nanocarrier. The results have shown a drug release quantity 18% higher in mimicking tumor environment than in the physiological one. Therefore, this study demonstrates the ability of CMNPs-plur to release a drug with pH dependence, which could be used in the future for the treatment of cancer "in situ" by means of controlled drug release.
NK Cell-Based Immunotherapy in Cancer Metastasis
Authors: Lorenzo-Herrero Seila , López-Soto Alejandro , Sordo-Bahamonde Christian , Gonzalez-Rodriguez Ana P , Vitale Massimo , Gonzalez Segundo
Published: December 2018

Metastasis represents the leading cause of cancer-related death mainly owing to the limited efficacy of current anticancer therapies on advanced malignancies. Although immunotherapy is rendering promising results in the treatment of cancer, many adverse events and factors hampering therapeutic efficacy, especially in solid tumors and metastases, still need to be solved. Moreover, immunotherapeutic strategies have mainly focused on modulating the activity of T cells, while Natural Killer (NK) cells have only recently been taken into consideration. NK cells represent an attractive target for cancer immunotherapy owing to their innate capacity to eliminate malignant tumors in a non-Major Histocompatibility Complex (MHC) and non-tumor antigen-restricted manner. In this review, we analyze the mechanisms and efficacy of NK cells in the control of metastasis and we detail the immunosubversive strategies developed by metastatic cells to evade NK cell-mediated immunosurveillance. We also share current and cutting-edge clinical approaches aimed at unleashing the full anti-metastatic potential of NK cells, including the adoptive transfer of NK cells, boosting of NK cell activity, redirecting NK cell activity against metastatic cells and the release of evasion mechanisms dampening NK cell immunosurveillance.
Effects of Antiangiogenetic Drugs on Microcirculation and Macrocirculation in Patients with Advanced-Stage Renal Cancer
Authors: Dalbeni Andrea , Ciccarese Chiara , Bevilacqua Michele , Benati Marco , Caimmi Cristian , Cerrito Luca , Famà Federico , Iacovelli Roberto , Mantovani Anna , Meneguzzi Francesco , Minuz Pietro , Montagnana Martina , Orsolini Giovanni , Rossini Maurizio , Tortora Gianpaolo , Viapiana Ombretta , Fava Cristiano
Published: December 2018

Adverse cardiovascular effects, including hypertension, were described in patients with different cancers treated with tyrosine kinase inhibitors (TKI). The mechanism of TKI-related hypertension is still debated. The aim of this work was to study the effects of TKI on blood pressure (BP), searching for a relationship with possible causative factors in patients with metastatic renal cell carcinoma. We included 29 patients in a prospective, observational study; 22 were treated with a first-line drug (sunitinib), while seven participated in the second-line treatment (axitinib or cabozantinib). Patients were investigated at the beginning of antiangiogenic therapy (T0) and at one (T1), three (T2), and six months (T3) after treatment. Patients were evaluated by office blood pressure (BP) and ultrasonography to measure flow-mediated dilatation (FMD), and carotid artery distensibility (cDC) by echocardiography and nailfold capillaroscopy. Plasma endothelin-1 (p-ET-1), urine nitrates, and proteins were also measured. At T1, systolic BP, along with U proteins and p-ET-1, increased significantly. In patients with a clinically significant increase in BP (defined as either the need for an antihypertensive drug or systolic blood pressure (SBP) T1–T0 ≥10 and/or SBP ≥140 mmHg and/or diastolic blood pressure (DBP) T1–T0 ≥5 and/or DBP ≥90 mmHg), the urine nitrate concentration was lower at T0, whereas there were no differences in the p-ET-1 and U proteins. Seventeen participants showed changes in the capillaroscopic pattern at T1 with no association with BP increases. There were no differences in the FMD, cDC, and echocardiographic parameters. Our findings are consistent with those of previous studies about BP increases by TKI, and suggest a role of nitric oxide in BP maintenance in this population.
An Effective Approach to Improve the Photocatalytic Activity of Graphitic Carbon Nitride via Hydroxyl Surface Modification
Authors: Li Zizhen , Meng Xiangchao , Zhang Zisheng
Published: December 2018

In this work, we have developed a hydrothermal method to modify g-C3N4 with hydroxyl surface modification. Modified g-C3N4 has exhibited higher photocatalytic activity in the removal of phenolic compounds under visible light. The improvement may be due to the following merits: (1) Tuning of the hydrophobic surface of g-C3N4 to be hydrophilic; (2) improved adsorption energy, and (3) narrowed band gap for g-C3N4 after hydroxyl surface modification. This method is easy-to-operate, very effective in adding hydroxyl groups on the surface of C3N4, and may be extended to other systems to promote their photocatalytic activities in water treatment.
Destruction of Toluene, Naphthalene and Phenanthrene as Model Tar Compounds in a Modified Rotating Gliding Arc Discharge Reactor
Authors: Kong Xiangzhi , Zhang Hao , Li Xiaodong , Xu Ruiyang , Mubeen Ishrat , Li Li , Yan Jianhua
Published: December 2018

Tar removal is one of the greatest technical challenges of commercial gasification technologies. To find an efficient way to destroy tar with plasma, a rotating gliding arc (RGA) discharge reactor equipped with a fan-shaped swirling generator was used for model tar destruction in this study. The solution of toluene, naphthalene and phenanthrene is used as a tar surrogate and is destroyed in humid nitrogen. The influence of tar, CO2 and moisture concentrations, and the discharge current on the destruction efficiency is emphasized. In addition, the combination of Ni/γ-Al2O3 catalyst with plasma was tested for plasma catalytic tar destruction. The toluene, naphthalene and phenanthrene destruction efficiency reached up to 95.2%, 88.9%, and 83.9% respectively, with a content of 12 g/Nm3 tar, 12% moisture, 15% CO2, and a flow rate of 6 NL/min, whereas 9.3 g/kW·h energy efficiency was achieved. The increase of discharge current is advantageous in terms of decreasing black carbon production. The participation of Ni/γ-Al2O3 catalyst shows considerable improvement in destruction efficiency, especially at a relatively high flow rate (over 9 NL/min). The major liquid by-products are phenylethyne, indene, acenaphthylene and fluoranthene. The first two are majorly converted from toluene, acenaphthylene is produced by the co-reaction of toluene and naphthalene in the plasma, and fluoranthene is converted by phenanthrene.
Recent Development of Photocatalysts Containing Carbon Species: A Review
Authors: Shi Zheng-Jun , Ma Ming-Guo , Zhu Jie-Fang
Published: December 2018

Undoubtedly, carbon-based (nano)composites can be promising photocatalysts with improved photocatalytic activity due to the coupling effect from the incorporation of carbon species. In this mini-review, we focus on the recent development of photocatalysts based on carbon-based (nano)composites. TiO2 is well-known as a typical photocatalyst. Special attention is paid to the various types of carbon–TiO2 composites such as C-doped TiO2, N–C-doped TiO2, metal–C-doped TiO2, and other co-doped C/TiO2 composites. Various synthetic strategies including the solvothermal/hydrothermal method, sol–gel method, and template-directed method are reviewed for the preparation of carbon-based TiO2 composites. C/graphitic carbon nitride (g-C3N4) composites and ternary C-doped composites are also summarized and ascribed to the unique electronic structure of g-C3N4 and the synergistic effect of the ternary interfaces, respectively. In the end, we put forward the future perspective of the photocatalysts containing carbon species based on our knowledge.
Ocrelizumab Depletes CD20+ T Cells in Multiple Sclerosis Patients
Authors: Gingele Stefan , Jacobus Thais Langer , Konen Franz Felix , Hümmert Martin W. , Sühs Kurt-Wolfram , Schwenkenbecher Philipp , Ahlbrecht Jonas , Möhn Nora , Müschen Lars H. , Bönig Lena , Alvermann Sascha , Schmidt Reinhold E. , Stangel Martin , Jacobs Roland , Skripuletz Thomas
Published: December 2018

Ocrelizumab, a humanized monoclonal anti-CD20 antibody, has shown pronounced effects in reduction of disease activity in multiple sclerosis (MS) patients and has recently been approved for the treatment of patients with relapsing MS (RMS) and primary progressive MS (PPMS). CD20 is mainly expressed by B cells, but a subset of T cells (CD3+CD20+ T cells) also expresses CD20, and these CD20+ T cells are known to be a highly activated cell population. The blood of MS patients was analyzed with multicolor flow cytometry before and two weeks after treatment with ocrelizumab regarding the phenotype of peripheral blood mononuclear cells. CD20-expressing CD3+ T cells were found in blood samples of all MS patients, accounted for 2.4% of CD45+ lymphocytes, and constituted a significant proportion (18.4%) of all CD20+ cells. CD3+CD20+ T cells and CD19+CD20+ B cells were effectively depleted two weeks after a single administration of 300 mg ocrelizumab. Our results demonstrate that treatment with ocrelizumab does not exclusively target B cells, but also CD20+ T cells, which account for a substantial amount of CD20-expressing cells. Thus, we speculate that the efficacy of ocrelizumab might also be mediated by the depletion of CD20-expressing T cells.
Conceptualizing Youth Participation in Children’s Health Research: Insights from a Youth-Driven Process for Developing a Youth Advisory Council
Authors: Arunkumar Krishna , Bowman Drew D. , Coen Stephanie E. , El-Bagdady Mohammad A. , Ergler Christina R. , Gilliland Jason A. , Mahmood Ahad , Paul Suraj
Published: December 2018

Given the power asymmetries between adults and young people, youth involvement in research is often at risk of tokenism. While many disciplines have seen a shift from conducting research on youth to conducting research with and for youth, engaging children and teens in research remains fraught with conceptual, methodological, and practical challenges. Arnstein’s foundational Ladder of Participation has been adapted in novel ways in youth research, but in this paper, we present a new rendering: a ‘rope ladder.’ This concept came out of our youth-driven planning process to develop a Youth Advisory Council for the Human Environments Analysis Laboratory, an interdisciplinary research laboratory focused on developing healthy communities for young people. As opposed to a traditional ladder, composed of rigid material and maintaining a static position, the key innovation of our concept is that it integrates a greater degree of flexibility and mobility by allowing dynamic movement beyond a 2D vertical plane. At the same time, the pliable nature of the rope makes it both responsive and susceptible to exogenous forces. We argue that involving youth in the design of their own participatory framework reveals dimensions of participation that are important to youth, which may not be captured by the existing participatory models.
Microstructure and Properties of CoCrFeNi(WC) High-Entropy Alloy Coatings Prepared Using Mechanical Alloying and Hot Pressing Sintering
Authors: Xu Juan , Wang Shouren , Shang Caiyun , Huang Shifeng , Wang Yan
Published: December 2018

The CoCrFeNi high-entropy alloy coatings (HEACs) with different weight ratios (10 and 30 wt.%) of WC additions have been prepared using mechanical alloying and a vacuum hot pressing sintering technique on a Q235 steel substrate. The microstructures, microhardness, wear resistance, and corrosion resistance of HEACs were studied. The CoCrFeNi(WC) powders were obtained by mixing the CoCrFeNi HEA powders and WC particles. The sintered products of both HEACs with high relative density contained one solid solution phase with face-centered cubic structure, WC, and unknown precipitate phases. The transition boundary had a good metallurgical bonding with the coating and substrate. The average microhardness values of CoCrFeNi HEACs with 10 and 30 wt.% WC additions reached 475 and 531 HV respectively, which were far higher than that of the substrate (160 HV). Moreover, both coatings exhibited better wear resistance than the substrate under the same wear conditions. The 30 wt.% WC HEAC displayed the lower friction coefficient, and the shallower wear groove depth. The grain refinement strengthening and second-phase particle strengthening could be beneficial to the enhanced hardness and wear resistance of coatings with WC additions. The corrosion behavior of the tested samples in the 3.5 wt.% NaCl solution were investigated using electrochemical polarization measurements. The CoCrFeNi(WC) coatings all revealed the improved corrosion resistance. Especially, a 10 wt.% WC addition remarkably enhanced the comprehensive corrosion resistance and easy passivation of CoCrFeNi HEAC.
Removal of Acid Orange 7 from Aqueous Solution by Metal-Organic Frameworks
Authors: Yoon Sungwon , Calvo James J. , So Monica C.
Published: December 2018

We investigated the removal of a harmful anionic dye, acid orange 7 (AO7), from aqueous solution using metal-organic frameworks (MOFs). We prepared four different MOFs (ZIF-8, ZIF-67, UiO-66, UiO-66-NH2) by solvothermal reactions and then tested their adsorption of AO7. Infrared spectra and adsorption capacity data confirmed the removal of AO7 from aqueous solution. The factors we investigated affecting adsorption capacity include variation of the organic linkers and metal clusters of the MOFs. Our results suggest that the hydrogen bonding, π–π interactions, and zeta potentials facilitate the removal of AO7 from water. Of the four MOFs examined, ZIF-67 exhibited the highest adsorption capacity of AO7 and can be regenerated easily.
Molecular and Segmental Orientational Order in a Smectic Mesophase of a Thermotropic Ionic Liquid Crystal
Authors: Dai Jing , Kharkov Boris B. , Dvinskikh Sergey V.
Published: December 2018

We investigate conformational dynamics in the smectic A phase formed by the mesogenic ionic liquid 1-tetradecyl-3-methylimidazolium nitrate. Solid-state high-resolution 13C nuclear magnetic resonance (NMR) spectra are recorded in the sample with the mesophase director aligned in the magnetic field of the NMR spectrometer. The applied NMR method, proton encoded local field spectroscopy, delivers heteronuclear dipolar couplings of each 13C spin to its 1H neighbours. From the analysis of the dipolar couplings, orientational order parameters of the C–H bonds along the hydrocarbon chain were determined. The estimated value of the molecular order parameter S is significantly lower compared to that in smectic phases of conventional non-ionic liquid crystals.
Machine Learning in Classification Time Series with Fractal Properties
Authors: Kirichenko Lyudmyla , Radivilova Tamara , Bulakh Vitalii
Published: December 2018

The article presents a novel method of fractal time series classification by meta-algorithms based on decision trees. The classification objects are fractal time series. For modeling, binomial stochastic cascade processes are chosen. Each class that was singled out unites model time series with the same fractal properties. Numerical experiments demonstrate that the best results are obtained by the random forest method with regression trees. A comparative analysis of the classification approaches, based on the random forest method, and traditional estimation of self-similarity degree are performed. The results show the advantage of machine learning methods over traditional time series evaluation. The results were used for detecting denial-of-service (DDoS) attacks and demonstrated a high probability of detection.
Entropy Analysis of the Flat Tip Leakage Flow with Delayed Detached Eddy Simulation
Authors: Li Hui , Su Xinrong , Yuan Xin
Published: December 2018

In unshrouded turbine rotors, the tip leakage vortices develop and interact with the passage vortices. Such complex leakage flow causes the major loss in the turbine stage. Due to the complex turbulence characteristics of the tip leakage flow, the widely used Reynolds Averaged Navier–Stokes (RANS) approach may fail to accurately predict the multi-scale turbulent flow and the related loss. In order to effectively improve the turbine efficiency, more insights into the loss mechanism are required. In this work, a Delayed Detached Eddy Simulation (DDES) study is conducted to simulate the flow inside a high pressure turbine blade, with emphasis on the tip region. DDES results are in good agreement with the experiment, and the comparison with RANS results verifies the advantages of DDES in resolving detailed flow structures of leakage flow, and also in capturing the complex turbulence characteristics. The snapshot Proper Orthogonal Decomposition (POD) method is used to extract the dominant flow features. The flow structures and the distribution of turbulent kinetic energy reveal the development of leakage flow and its interaction with the secondary flow. Meanwhile, it is found that the separation bubble (SB) is formed in tip clearance. The strong interactions between tip leakage vortex (TLV) and the up passage vortex (UPV) are the main source of unsteady effects which significantly enhance the turbulence intensity. Based on the DDES results, loss analysis of tip leakage flow is conducted based on entropy generation rates. It is found that the viscous dissipation loss is much stronger than heat transfer loss. The largest local loss occurs in the tip clearance, and the interaction between the leakage vortex and up passage vortex promotes the loss generation. The tip leakage flow vortex weakens the strength of up passage vortex, and loss of up passage flow is reduced. Comparing steady and unsteady effects to flow field, we found that unsteady effects of tip leakage flow have a large influence on flow loss distribution which cannot be ignored. To sum up, the current DDES study about the tip leakage flow provides helpful information about the loss generation mechanism and may guide the design of low-loss blade tip.
Experience in the Use of Social Software to Support Student Learning in University Courses of Science and Engineering Degrees
Authors: Díez-Pascual Ana María , García-Díaz Pilar , Peña-Capilla Rafael
Published: December 2018

A wiki is an easy-to-use online tool for teachers and students, as it is a collaborative website that provides the opportunity to develop and modify its content to every member in an interactive and fast way. This paper comparatively describes experiences in the implementation of wikis as voluntary activities in first-year courses in a degree in Chemistry and third-year courses in a degree in Telecommunication System Engineering. The main goal of using the wikis was to achieve collaboration among students to generate knowledge. The developed methodology was applied to the resolution of exercises, problems, and test questions, as well as to the elaboration of class notes and a bilingual glossary. The approach turned the students into active learners, increasing their interest in the course contents, promoting knowledge exchange among students and encouraging the self-management of their learning process. The role of the teacher was to provide feedback to the students in order to ensure the accuracy of the contents. Four different patterns were distinguished among the students according to their participation level in the wiki. The students who were most committed to the courses were also the most involved in the wikis, and the combination resulted in the students’ success. The results obtained for the degree in Chemistry were better than those of the degree in Telecommunication System Engineering, which was ascribed to the increased connection among the first-year students. The didactic strategy was very positive, although the percentage of participation in the wikis was somewhat low, in particular for the third-year students, who were more independent and self-organized. Initially, the number of wiki visits increased suddenly, and then moved to a long period of lower activity in the degree of Chemistry and lethargy in the degree of Telecommunication System Engineering. Therefore, it is desirable to introduce modifications in the approach, such as flexible and consensual planning with the students in order to ensure their full engagement.
Experimental Study on the Movement and Evolution of Overburden Strata Under Reamer-Pillar Coal Mining Based on Distributed Optical Fiber Monitoring
Authors: Piao Chunde , Lei Shaogang , Yang Jiakun , Sang Lihong
Published: December 2018

Focusing on the deterioration of the surface ecological environment caused by large-scale exploitation of the Jurassic coal field in northern Shaanxi, the three-dimensional similar material test model is made to simulate the extraction of shallow coal seam. Using Brillouin optical time-domain analysis (BOTDA) optical fiber distributed sensing technology, this paper studied the strain distribution rule and movement characteristics of strata under reamer-pillar mining, analyzed the stability of the remaining coal pillars in the mining area, and obtained the strain contour graph of strata through calculations. The research result shows that the deformation of coal pillars in a safety-critical state under reamer-pillar mining experiences three stages. The stratum deformation is distributed in the shape of a pyramid with the mining area as the center. On the basis of the strain distribution of strata, the settlement curve and subsidence curve of strata deformation are determined to obtain the rupture angle and angle of draw. After being compared with the measured data, the angle values are almost the same.
Experimental Investigation of the Thermal Performance of a Wickless Heat Pipe Operating with Different Fluids: Water, Ethanol, and SES36. Analysis of Influences of Instability Processes at Working Operation Parameters
Authors: Andrzejczyk Rafal
Published: December 2018

In this study, the influences of different parameters on performance of a wickless heat pipe have been presented. Experiments have been carried out for an input power range from 50 W to 300 W, constant cooling water mass flow rate of 0.01 kg/s, and constant temperature at the inlet to condenser of 10 °C. Three working fluids have been tested: water, ethanol, and SES36 (1,1,1,3,3-Pentafluorobutane) with different filling ratios (0.32, 0.51, 1.0). The wall temperature in different locations (evaporation section, adiabatic section, and condenser section), as well as operating pressure inside two phase closed thermosyphon have been monitored. The wickless heat pipe was made of 0.01 m diameter copper tube, which consists of an evaporator, adiabatic, and condensation sections with the same length (0.4 m). For all working fluids, a dynamic start-up effect caused by heat conduction towards the liquid pool was observed. Only the thermosyphon filled with SES36 was observed to have operation limitation caused by achieving the boiling limit in TPCTs (two-phase closed thermosyphons). The geyser boiling effect has been observed only for thermosyphon filled with ethanol and for a high filling ratio. The performance of the thermosyphon determined the form of the heat transfer resistance of the TPCT and it was found to be dependent of input power and filling ratio, as well as the type of working fluid and AR (aspect ratio). Comparison with other authors would seem to indicate that lower AR results in higher resistance; however, the ratio of condenser section length to inside diameter of pipe is also a very important parameter. Generally, performance of the presented thermosyphon is comparable to other constructions.
A Novel Electrochemical Hydrogen Storage-Based Proton Battery for Renewable Energy Storage
Authors: Oberoi Amandeep , Nijhawan Parag , Singh Parminder
Published: December 2018

The inherently variable nature of renewable energy sources makes them storage-dependent when providing a reliable and continuous energy supply. One feasible energy-storage option that could meet this challenge is storing surplus renewable energy in the form of hydrogen. In this context, storage of hydrogen electrochemically in porous carbon-based electrodes is investigated. Measurements of hydrogen storage capacity, proton conductivity, and capacitance due to electrical double layer of several porous activated carbon electrodes are reported. The hydrogen storage capacity of the tested electrodes is found in the range of 0.61−1.05 wt.%, which compares favorably with commercially available metal hydride-based hydrogen storage, lithium polymer batteries, and lithium ion batteries in terms of gravimetric energy density. The highest obtained proton conductivity was 0.0965 S/cm, which is near to that of the commercial polymer-based proton conductor, nafion 117, under fully hydrated conditions. The obtained capacitance due to double-layers of the tested electrodes was in the range of 28.3–189.4 F/g. The relationship between specific surface area, micropore volume and hydrogen storage capacity of the carbon electrodes is discussed. The contribution of capacitance to the equivalent hydrogen storage capacity of carbon electrodes is reported. The implications of the obtained experimental results are discussed.
Fractional-Order Model Predictive Frequency Control of an Islanded Microgrid
Authors: Chen Min-Rong , Zeng Guo-Qiang , Dai Yu-Xing , Lu Kang-Di , Bi Da-Qiang
Published: December 2018

Optimal frequency control of an islanded microgrid has been a challenging issue in the research field of microgrids. Recently, fractional-order calculus theory and some related control methods have attempted to handle this issue. In this paper, a novel fractional-order model predictive control (FOMPC) method is proposed to achieve the optimal frequency control of an islanded microgrid by introducing a fractional-order integral cost function into model predictive control (MPC) algorithm. Firstly, a discrete state-space model is derived for the optimal frequency control problem of an islanded microgrid. Afterward, a fractional-order integral cost function is designed to guide the FOMPC algorithm to obtain optimal control law by borrowing the Grünwald-Letnikov (GL) definition of fractional order calculus. Six simulation studies have been carried out to illustrate the superiority of FOMPC to conventional MPC under dynamical load disturbances, perturbed system parameters and random dynamical power fluctuation of wind turbines.
A Distributed Control Strategy for Islanded Single-Phase Microgrids with Hybrid Energy Storage Systems Based on Power Line Signaling
Authors: Quintana-Barcia Pablo , Dragicevic Tomislav , Garcia Jorge , Ribas Javier , Guerrero Josep M.
Published: December 2018

Energy management control is essential to microgrids (MGs), especially to single-phase ones. To handle the variety of distributed generators (DGs) that can be found in a MG, e.g., renewable energy sources (RESs) and energy storage systems (ESSs), a coordinated power regulation is required. The latter are generally battery-based systems whose lifetime is directly related to charge/discharge processes, whereas the most common RESs in a MG are photovoltaic (PV) units. Hybrid energy storage systems (HESS) extend batteries life expectancy, thanks to the effect of supercapacitors, but they also require more complex control strategies. Conventional droop methodologies are usually applied to provide autonomous and coordinated power control. This paper proposes a method for coordination of a single-phase MG composed by a number of sources (HESS, RES, etc.) using power line signaling (PLS). In this distributed control strategy, a signal whose frequency is higher than the grid is broadcasted to communicate with all DGs when the state of charge (SoC) of the batteries reaches a maximum value. This technique prevents batteries from overcharging and maximizes the power contribution of the RESs to the MG. Moreover, different commands apart from the SoC can be broadcasted, just by changing to other frequency bands. The HESS master unit operates as a grid-forming unit, whereas RESs act as grid followers. Supercapacitors in the HESS compensate for energy peaks, while batteries respond smoothly to changes in the load, also expanding its lifetime due to less aggressive power references. In this paper, a control structure that allows the implementation of this strategy in single-phase MGs is presented, with the analysis of the optimal range of PLS frequencies and the required self-adaptive proportional-resonant controllers.
Superconducting AC Homopolar Machines for High-Speed Applications
Authors: Kalsi Swarn , Hamilton Kent , Buckley Robert George , Badcock Rodney Alan
Published: December 2018

This paper presents a novel high-speed alternating current (AC) homopolar motor/generator design using stationary ReBCO excitation windings. Compact, lightweight, high-efficiency motors and generators are sought for a multitude of applications. AC homopolar synchronous machines are an ideal choice for such applications as these machines enable very high rotational frequencies. These machines include both AC armature winding and direct current (DC) excitation winding within the stationary part of the machine. The stationary excitation winding magnetizes a solid steel rotor, enabling operating speeds limited only by the mechanical stress limit of the rotor steel. The operating speeds are many multiples of conventional power 50/60 Hz machines. Significant cooling requirements limit machines of this type utilizing copper excitation windings to only a few kilowatts. However, megawatt ratings become possible when superconductor coils are used. This paper describes the design and analysis of an AC homopolar machine in the context of developing a 500 kW flywheel system to be used for energy recovery and storage in commuter rail subway systems. Different approaches are discussed for an AC armature employing conventional copper coils. Challenges of building and cooling both armature and field coils are discussed and preferred approaches are suggested. Calculations of the machine performance are then made.
Reducing High Energy Demand Associated with Air-Conditioning Needs in Saudi Arabia
Authors: Alshahrani Jubran , Boait Peter
Published: December 2018

Electricity consumption in the Kingdom of Saudi Arabia (KSA) has grown at an annual rate of about 7% as a result of population and economic growth. The consumption of the residential sector accounts for over 50% of the total energy generation. Moreover, the energy consumption of air-conditioning (AC) systems has become 70% of residential buildings’ total electricity consumption in the summer months, leading to a high peak electricity demand. This study investigates solutions that will tackle the problem of high energy demand associated with KSA’s air-conditioning needs in residential buildings. To reduce the AC energy consumption in the residential sector, we propose the use of smart control in the thermostat settings. Smart control can be utilized by (i) scheduling and advance control of the operation of AC systems and (ii) remotely setting the thermostats appropriately by the utilities. In this study, we model typical residential buildings and, crucially, occupancy behavior based on behavioral data obtained through a survey. The potential impacts in terms of achievable electricity savings of different AC operation modes for residential houses of Riyadh city are presented. The results from our computer simulations show that the solutions intended to reduce energy consumption effectively, particularly in the advance mode of operation, resulted in a 30% to 40% increase in total annual energy savings.
Communication Performance Assessment for Advanced Metering Infrastructure
Authors: Teng Jen-Hao , Chao Chia-Wei , Liu Bin-Han , Huang Wei-Hao , Chiu Jih-Ching
Published: December 2018

Advanced Metering Infrastructure (AMI), the foundation of smart grids, can be used to provide numerous intelligent power applications and services based on the data acquired from AMI. Effective and efficient communication performance between widely-spread smart meters and Data Concentrator Units (DCUs) is one of the most important issues for the successful deployment and operation of AMI and needs to be further investigated. This paper proposes an effective Communication Performance Index (CPI) to assess and supervise the communication performance of each smart meter. Some communication quality measurements that can be easily acquired from a smart meter such as reading success rate and response time are used to design the proposed CPI. Fuzzy logic is adopted to combine these measurements to calculate the proposed CPI. The CPIs for communication paths, DCUs and whole AMI can then be derived from meter CPIs. Simulation and experimental results for small-scale AMIs demonstrate the validity of the proposed CPI. Through the calculated CPIs, the communication performance and stability for AMI can be effectively assessed and supervised.
Elliot and Symmetric Elliot Extreme Learning Machines for Gaussian Noisy Industrial Thermal Modelling
Authors: Salmeron Jose L. , Ruiz-Celma Antonio
Published: December 2018

This research proposes an Elliot-based Extreme Learning Machine approach for industrial thermal processes regression. The main contribution of this paper is to propose an Extreme Learning Machine model with Elliot and Symmetric Elliot activation functions that will look for the fittest number of neurons in the hidden layer. The methodological proposal is tested on an industrial thermal drying process. The thermal drying process is relevant in many industrial processes such as the food industry, biofuels production, detergents and dyes in powder production, pharmaceutical industry, reprography applications, textile industries and others. The methodological proposal of this paper outperforms the following techniques: Linear Regression, k-Nearest Neighbours regression, Regression Trees, Random Forest and Support Vector Regression. In addition, all the experiments have been benchmarked using four error measurements (MAE, MSE, MEADE, R 2 ).
A Full-bridge Director Switches based Multilevel Converter with DC Fault Blocking Capability and Its Predictive Control Strategy
Authors: Zhu Jin , Wei Tongzhen , Huo Qunhai , Yin Jingyuan
Published: December 2018

Voltage source converter-based high-voltage direct current transmission system (VSC-HVDC) technology has been widely used. However, traditional half-bridge sub module (HBSM)-based module multilevel converter (MMC) cannot block a DC fault current. This paper proposes that a full-bridge director switches based multi-level converter can offer features such as DC side fault blocking capability and is more compact and lower cost than other existing MMC topologies. A suitable predictive control strategy is proposed to minimize the error of the output AC current and the capacitor voltage of the sub-module while the director switches are operated in low-frequency mode. The validity of the proposed topology and control method is demonstrated based on simulation and experimental studies.
Simulation and Analysis of Perturbation and Observation-Based Self-Adaptable Step Size Maximum Power Point Tracking Strategy with Low Power Loss for Photovoltaics
Authors: Zhu Yinxiao , Kim Moon Keun , Wen Huiqing
Published: December 2018

Photovoltaic (PV) techniques are widely used in daily life. In addition to the material characteristics and environmental conditions, maximum power point tracking (MPPT) techniques are an efficient means to maximize the output power and improve the utilization of solar power. However, the conventional fixed step size perturbation and observation (P&O) algorithm results in perturbations and power loss around the maximum power point in steady-state operation. To reduce the power loss in steady-state operation and improve the response speed of MPPT, this study proposes a self-adaptable step size P&O-based MPPT algorithm with infinitesimal perturbations. This algorithm combines four techniques to upgrade the response speed and reduce the power loss: (1) system operation state determination, (2) perturbation direction decision, (3) adaptable step size, and 4) natural oscillation control. The simulation results validate the proposed algorithm and illustrate its performances in operational procedures.
Analysis of the Methodology to Obtain Several Key Indicators Performance (KIP), by Energy Retrofitting of the Actual Building to the District Heating Fuelled by Biomass, Focusing on nZEB Goal: Case of Study
Authors: Castrillón Mendoza Rosaura , Rey Hernández Javier M. , Velasco Gómez Eloy , San José Alonso Julio F. , Rey Martínez Francisco J.
Published: December 2018

In order to achieve the objectives of the European 20/20/20 strategy, and to obtain a greater energy efficiency, integration of renewable energies and the reduction of carbon emissions, a District Heating (DH) system has been designed by the University of Valladolid (UVa), Spain, one of the most important DH fed by biomass fuel in Spain, supplying heating and domestic hot water (DHW) to 31 buildings in Valladolid, the majority of them, educational buildings on the University Campus. The aims of this paper were to study the change from an energy system fueled by natural gas to District Heating by biomass in a building on the campus of the University of Valladolid—the School of Engineering (EII)—studying its consumption from its connection to the District Heating system. An energy management methodology such as ISO 50001 is carried out, applied to efficiency systems in buildings, thus establishing new criteria of sustainability and economic value. In this paper, energy management will also be analyzed in accordance with the proposed tools of an Energy Management System (EMS) applied to the EII building, through the measurement of energy parameters, calculation of thermal consumption, thermal energy savings as a result of the change from system to District Heating by biomass, economic savings, reduction of environmental impact and indicators of thermal efficiency I100 and CUSUM indicator. Finally, the primary renewable and non-renewable energy efficiency indicators for the new District Heating system will be determined. The concept of the near Zero Energy Buildings is defined in the European Union (EU) in order to analyze an approach to an nZEB which results from replacing the natural gas heating system by a biomass District Heating system.
Fault-Tolerant Control of Quadcopter UAVs Using Robust Adaptive Sliding Mode Approach
Authors: Nguyen Ngoc , Hong Sung
Published: December 2018

In this paper, a fault-tolerant control method is proposed for quadcopter unmanned aerial vehicles (UAV) to account for system uncertainties and actuator faults. A mathematical model of the quadcopter UAV is first introduced when faults occur in actuators. A normal adaptive sliding mode control (NASMC) approach is proposed as a baseline controller to handle the chattering problem and system uncertainties, which does not require information of the upper bound. To improve the performance of the NASMC scheme, radial basis function neural networks are combined with an adaptive scheme to make a quick compensation in presence of system uncertainties and actuator faults. The Lyapunov theory is applied to verify the stability of the proposed methods. The effectiveness of modified ASMC algorithm is compared with that of NASMC using numerical examples under different faulty conditions.
The Hungry Bob Fire & Fire Surrogate Study: A 20-Year Evaluation of the Treatment Effects
Authors: McCaskill George L.
Published: December 2018

The Hungry Bob fuels reduction project was part of a 12-site National Fire and Fire Surrogate (FFS) network of experiments conducted across the United States from the late 1990s through the early 2000s to determine the regional differences in applying alternative fuel-reduction treatments to forests. The Hungry Bob project focused on restoration treatments applied in low elevation, dry second-growth ponderosa pine (Pinus ponderosa subsp. ponderosa (Douglas ex C. Lawson) and Douglas-fir (Pseudotsuga menziesii subsp. glauca (Beissn.) Franco forests of northeastern Oregon. Treatments included a single entry thin from below in 1998, a late season burn in 2000, a thin (1999) followed by burning (2000), and a no-treatment control. This paper represents results 20 years after treatments and focuses on the treatment effects upon tree diameter growth, crown health, and ladder fuel conditions within the dry eastside stands. The Thin + Burn units produced the best diameter growth in ponderosa pine trees, whereas the Thin units had the best growth for Douglas-fir. The Burn treatment did not improve diameter growth over the Controls. The Thin + Burn treatments also produced trees with the highest tree crown ratios. The Burn unit trees had lower crown ratios compared to the Control trees. The crown reduction (reduction in tree crown ratio since 2004) was largest in the Burn-only units and smallest in the Thin + Burn units. Finally, the heights to the lower tree crowns were highest in the Thin + Burn trees and lowest in the Burn unit trees. Based upon the 20-year responses, the Thin + Burn treatments produced the best conditions for stand growth, while limiting fire stress upon residual tree crowns. It also proved most effective at reducing ladder fuels as represented by higher tree crown heights.
A Framework for Improving the Engagement of Medical Practitioners in an E-Training Platform for Tuberculosis Care and Prevention
Authors: Ali Syed Mustafa , Curralo Ana Filomena , Boulos Maged N. Kamel , Paiva Sara
Published: December 2018

We propose a new framework to improve the engagement of medical practitioners in a planned e-training platform for the successful identification and effective management of presumptive cases of tuberculosis (TB) in Pakistan. Our work is aligned with the World Health Organization’s TB-DOTS (Directly Observed Treatment Short-course) strategy for promoting the effective management of tuberculosis. We start by presenting previous work done at Mercy Corps Pakistan for training medical practitioners, then present the results of a recent survey we administered to a random sample of medical practitioners in Pakistan to learn about their requirements and readiness to embrace a new e-training platform and methodology. Informed by feedback from the survey, we formulated a detailed requirement analysis of the five key learning areas (or phases) that we believe are fundamental to the success of a TB e-training platform. Moreover, survey results revealed that an on-spot, on-demand, and competency-based learning tool can potentially improve the engagement of medical practitioners in the process. Building on the insights gained from the survey, we finally describe our initial UX (user experience) prototypes for phase 1, which corresponds to the identification of presumptive tuberculosis cases.