bluuebunny/crossref_metadata_2025 huggingface dataset:
Crystal structure and substrate-induced activation of ADAMTS13
Authors: Petri Anastasis , Kim Hyo Jung , Xu Yaoxian , de Groot Rens , Li Chan , Vandenbulcke Aline , Vanhoorelbeke Karen , Emsley Jonas , Crawley James T. B.
Published: August 2019

Platelet recruitment to sites of blood vessel damage is highly dependent upon von Willebrand factor (VWF). VWF platelet-tethering function is proteolytically regulated by the metalloprotease ADAMTS13. Proteolysis depends upon shear-induced conformational changes in VWF that reveal the A2 domain cleavage site. Multiple ADAMTS13 exosite interactions are involved in recognition of the unfolded A2 domain. Here we report through kinetic analyses that, in binding VWF, the ADAMTS13 cysteine-rich and spacer domain exosites bring enzyme and substrate into proximity. Thereafter, binding of the ADAMTS13 disintegrin-like domain exosite to VWF allosterically activates the adjacent metalloprotease domain to facilitate proteolysis. The crystal structure of the ADAMTS13 metalloprotease to spacer domains reveals that the metalloprotease domain exhibits a latent conformation in which the active-site cleft is occluded supporting the requirement for an allosteric change to enable accommodation of the substrate. Our data demonstrate that VWF functions as both the activating cofactor and substrate for ADAMTS13.
Sp1-regulated expression of p11 contributes to motor neuron degeneration by membrane insertion of TASK1
Authors: García-Morales Victoria , Rodríguez-Bey Guillermo , Gómez-Pérez Laura , Domínguez-Vías Germán , González-Forero David , Portillo Federico , Campos-Caro Antonio , Gento-Caro Ángela , Issaoui Noura , Soler Rosa M. , Garcera Ana , Moreno-López Bernardo
Published: August 2019

Disruption in membrane excitability contributes to malfunction and differential vulnerability of specific neuronal subpopulations in a number of neurological diseases. The adaptor protein p11, and background potassium channel TASK1, have overlapping distributions in the CNS. Here, we report that the transcription factor Sp1 controls p11 expression, which impacts on excitability by hampering functional expression of TASK1. In the SOD1-G93A mouse model of ALS, Sp1-p11-TASK1 dysregulation contributes to increased excitability and vulnerability of motor neurons. Interference with either Sp1 or p11 is neuroprotective, delaying neuron loss and prolonging lifespan in this model. Nitrosative stress, a potential factor in human neurodegeneration, stimulated Sp1 expression and human p11 promoter activity, at least in part, through a Sp1-binding site. Disruption of Sp1 or p11 also has neuroprotective effects in a traumatic model of motor neuron degeneration. Together our work suggests the Sp1-p11-TASK1 pathway is a potential target for treatment of degeneration of motor neurons.
Nucleosome and ubiquitin position Set2 to methylate H3K36
Authors: Bilokapic Silvija , Halic Mario
Published: August 2019

Histone H3 lysine 36 methylation (H3K36me) is a conserved histone modification deposited by the Set2 methyltransferases. Recent findings show that over-expression or mutation of Set2 enzymes promotes cancer progression, however, mechanisms of H3K36me are poorly understood. Set2 enzymes show spurious activity on histones and histone tails, and it is unknown how they obtain specificity to methylate H3K36 on the nucleosome. In this study, we present 3.8 Å cryo-EM structure of Set2 bound to the mimic of H2B ubiquitinated nucleosome. Our structure shows that Set2 makes extensive interactions with the H3 αN, the H3 tail, the H2A C-terminal tail and stabilizes DNA in the unwrapped conformation, which positions Set2 to specifically methylate H3K36. Moreover, we show that ubiquitin contributes to Set2 positioning on the nucleosome and stimulates the methyltransferase activity. Notably, our structure uncovers interfaces that can be targeted by small molecules for development of future cancer therapies.
B1 oligomerization regulates PML nuclear body biogenesis and leukemogenesis
Authors: Li Yuwen , Ma Xiaodan , Chen Zhiming , Wu Haiyan , Wang Pengran , Wu Wenyu , Cheng Nuo , Zeng Longhui , Zhang Hao , Cai Xun , Chen Sai-Juan , Chen Zhu , Meng Guoyu
Published: August 2019

ProMyelocyticLeukemia (PML) protein can polymerize into a mega-Dalton nuclear assembly of 0.1–2 μm in diameter. The mechanism of PML nuclear body biogenesis remains elusive. Here, PMLRBCC is successfully purified. The gel filtration and ultracentrifugation analysis suggest a previously unrecognized sequential oligomerization mechanism via PML monomer, dimer, tetramer and N-mer. Consistently, PML B1-box structure (2.0 Å) and SAXS characterization reveal an unexpected networking by W157-, F158- and SD1-interfaces. Structure-based perturbations in these B1 interfaces not only impair oligomerization in vitro but also abolish PML sumoylation and nuclear body biogenesis in HeLaPml-/- cell. More importantly, as demonstrated by in vivo study using transgenic mice, PML-RARα (PR) F158E precludes leukemogenesis. In addition, single cell RNA sequencing analysis shows that B1 oligomerization is an important regulator in PML-RARα-driven transactivation. Altogether, these results not only define a previously unrecognized B1-box oligomerization in PML, but also highlight oligomerization as an important factor in carcinogenesis.
Aeolian transport of viable microbial life across the Atacama Desert, Chile: Implications for Mars
Authors: Azua-Bustos Armando , González-Silva Carlos , Fernández-Martínez Miguel Ángel , Arenas-Fajardo Cristián , Fonseca Ricardo , Martín-Torres F. Javier , Fernández-Sampedro Maite , Fairén Alberto G. , Zorzano María-Paz
Published: August 2019

Here we inspect whether microbial life may disperse using dust transported by wind in the Atacama Desert in northern Chile, a well-known Mars analog model. By setting a simple experiment across the hyperarid core of the Atacama we found that a number of viable bacteria and fungi are in fact able to traverse the driest and most UV irradiated desert on Earth unscathed using wind-transported dust, particularly in the later afternoon hours. This finding suggests that microbial life on Mars, extant or past, may have similarly benefited from aeolian transport to move across the planet and find suitable habitats to thrive and evolve.
A Ca2+/CaM-regulated transcriptional switch modulates stomatal development in response to water deficit
Authors: Yoo Chan Yul , Mano Noel , Finkler Aliza , Weng Hua , Day Irene S. , Reddy Anireddy S. N. , Poovaiah B. W. , Fromm Hillel , Hasegawa Paul M. , Mickelbart Michael V.
Published: August 2019

Calcium (Ca2+) signals are decoded by the Ca2+-sensor protein calmodulin (CaM) and are transduced to Ca2+/CaM-binding transcription factors to directly regulate gene expression necessary for acclimation responses in plants. The molecular mechanisms of Ca2+/CaM signal transduction processes and their functional significance remains enigmatic. Here we report a novel Ca2+/CaM signal transduction mechanism that allosterically regulates DNA-binding activity of GT2-LIKE 1 (GTL1), a transrepressor of STOMATAL DENSITY AND DISTRIBUTION 1 (SDD1), to repress stomatal development in response to water stress. We demonstrated that Ca2+/CaM interaction with the 2nd helix of the GTL1 N-terminal trihelix DNA-binding domain (GTL1N) destabilizes a hydrophobic core of GTL1N and allosterically inhibits 3rd helix docking to the SDD1 promoter, leading to osmotic stress-induced Ca2+/CaM-dependent activation (de-repression) of SDD1 expression. This resulted in GTL1-dependent repression of stomatal development in response to water-deficit stress. Together, our results demonstrate that a Ca2+/CaM-regulated transcriptional switch on a trihelix transrepressor directly transduces osmotic stress to repress stomatal development to improve plant water-use efficiency as an acclimation response.
The ESA Swarm mission to help ionospheric modeling: a new NeQuick topside formulation for mid-latitude regions
Authors: Pezzopane M. , Pignalberi A.
Published: August 2019

The ionospheric topside representation made by the NeQuick model is improved by correcting the H0 parameter used by the model to calculate the topside scale height. The task is accomplished by fitting the NeQuick topside analytical function through two anchor points: the F2-layer absolute electron density maximum; the electron density value as measured by Swarm satellites from December 2013 to September 2018. Specifically, two-dimensional grids of H0 as a function of foF2 and hmF2 are obtained, one by employing data from Swarm A and Swarm C, both flying at about 460 km of altitude, and the other one by employing data from Swarm B, flying at about 520 km of altitude. These two grids are used to calculate corrected values of H0, which allows a more reliable description of the topside region. The new NeQuick formulation is statistically validated by comparing corresponding modeled vertical total electron content values to those derived from COSMIC/FORMOSAT-3 measured Radio Occultation profiles, and those measured by Swarm satellites. The results show that the proposed formulation significantly improves the topside description made by the NeQuick model at mid latitudes, for both high and low solar activities. The International Reference Ionosphere model might benefit of its inclusion.
Crystal structures of cholera toxin in complex with fucosylated receptors point to importance of secondary binding site
Authors: Heim Joel B. , Hodnik Vesna , Heggelund Julie E. , Anderluh Gregor , Krengel Ute
Published: August 2019

Cholera is a life-threatening diarrhoeal disease caused by the human pathogen Vibrio cholerae. Infection occurs after ingestion of the bacteria, which colonize the human small intestine and secrete their major virulence factor – the cholera toxin (CT). The GM1 ganglioside is considered the primary receptor of the CT, but recent studies suggest that also fucosylated receptors such as histo-blood group antigens are important for cellular uptake and toxicity. Recently, a special focus has been on the histo-blood group antigen Lewisx (Lex), however, where and how the CT binds to Lex remains unclear. Here we report the high-resolution crystal structure (1.5 Å) of the receptor-binding B-subunits of the CT bound to the Lex trisaccharide, and complementary quantitative binding data for CT holotoxins. Lex, and also l-fucose alone, bind to the secondary binding site of the toxin, distinct from the GM1 binding site. In contrast, fucosyl-GM1 mainly binds to the primary binding site due to high-affinity interactions of its GM1 core. Lex is the first histo-blood group antigen of non-secretor phenotype structurally investigated in complex with CT. Together with the quantitative binding data, this allows unique insight into why individuals with non-secretor phenotype are more prone to severe cholera than so-called ‘secretors’.
Living bridges using aerial roots of ficus elastica – an interdisciplinary perspective
Authors: Ludwig Ferdinand , Middleton Wilfrid , Gallenmüller Friederike , Rogers Patrick , Speck Thomas
Published: August 2019

Here we report on a pilot study of the Living Root Bridges (LRBs) in the Indian State Meghalaya, which are grown with aerial roots ofFicus elastica, a facultative hemiepiphyte developing abundant aerial roots. Locals use these aerial roots to build living bridges, which strengthen themselves over time due to adaptive secondary growth and their capacity to form a mechanically stable structure via inosculations. An extensive inventory of LRBs in Meghalaya including data of location, altitude, approximate age and bridge length was performed in field studies. Root morphology was characterised by measurements of cross-sectional area and shape-related parameters and analysed in relation to the orientation of the roots. LRBs are found to occur mainly in the mountainous limestone rainforests whereF. elasticamay be native or traditionally cultivated. They cover an altitude range of 57–1211 m a.m.s.l. and display a length of 2 to 52.7 m. Some bridges are several hundreds of years old. Horizontally and vertically trained roots differ significantly in shape and cross-sectional area when approximately even-aged roots are compared. The results are discussed from an interdisciplinary perspective, considering the adaptive traits in the natural life cycle ofF. elasticaand possible applications in living architecture (Baubotanik).
Linkage of CD8+ T cell exhaustion with high-fat diet-induced tumourigenesis
Authors: Kado Tomonobu , Nawaz Allah , Takikawa Akiko , Usui Isao , Tobe Kazuyuki
Published: August 2019

Obesity increases the risk of cancer. Increased levels of hormones (such as oestrogen, insulin, insulin-like growth factor, and leptin), free fatty acid-induced production of reactive oxygen species, an altered intestinal microbiome and chronic inflammation are known to be associated with an increased cancer risk in obese subjects. However, the mechanism underlying the connection between obesity and cancer development remains elusive. Here, we show that a high-fat diet (HFD) promotes tumour initiation/progression and induces a phenotypic switch from PD-1− CD8+non-exhausted T cells to PD-1+ CD8+exhausted T cells in a murine breast cancer model. While PD-1− CD8+non-exhausted T cells predominated in the mammary glands of normal diet (ND)-fed mice, PD-1+ CD8+exhausted T cells accumulated in the developing tumours of HFD-fed mice. Gene expression profiles indicated that PD-1+ CD8+ T cells expressed higher levels of the tumour-trophic gene Opn and lower levels of the cytotoxic genes Ifng and Gzmb than did PD-1− CD8+ T cells. Our study provides a possible mechanistic linkage between obesity and cancer.
A biomimetic 3D model of hypoxia-driven cancer progression
Authors: Liverani Chiara , De Vita Alessandro , Minardi Silvia , Kang Yibin , Mercatali Laura , Amadori Dino , Bongiovanni Alberto , La Manna Federico , Ibrahim Toni , Tasciotti Ennio
Published: August 2019

The fate of tumors depends both on the cancer cells’ intrinsic characteristics and on the environmental conditions where the tumors reside and grow. Engineered in vitro models have led to significant advances in cancer research, allowing the investigation of cells in physiological environments and the study of disease mechanisms and processes with enhanced relevance. Here we present a biomimetic cancer model based on a collagen matrix synthesized through a biologically inspired process. We compared in this environment the responses of two breast tumor lineages characterized by different molecular patterns and opposite clinical behaviors: MCF-7 that belong to the luminal A subtype connected to an indolent course, and basal-like MDA-MB-231 connected to high-grade and aggressive disease. Cancer cells in the biomimetic matrix recreate a hypoxic environment that affects their growth dynamics and phenotypic features. Hypoxia induces apoptosis and the selection of aggressive cells that acquire expression signatures associated with glycolysis, angiogenesis, cell-matrix interaction, epithelial to mesenchymal transition and metastatic ability. In response to hypoxia MDA-MB-231 migrate on the collagen fibrils and undergo cellular senescence, while MCF-7 do not exhibit these behaviors. Our biomimetic model mimics the evolution of tumors with different grade of aggressiveness fostered by a hypoxic niche and provides a relevant technology to dissect the events involved in cancer progression.
BK channels regulate extracellular Tat-mediated HIV-1 LTR transactivation
Authors: Khan Nabab , Lakpa Koffi L. , Halcrow Peter W. , Afghah Zahra , Miller Nicole M. , Geiger Jonathan D. , Chen Xuesong
Published: August 2019

HIV-1 Tat is essential for HIV-1 replication and plays an important role in latent HIV-1 infection, HIV-1 associated neurological complication, and other HIV-1 comorbidities. Secreted from HIV-1 infected or transfected cells, Tat can be up-taken into cells by receptor-mediated endocytosis and internalized into endolysosomes. To reach nucleus where it can facilitate HIV-1 viral replication, exogenous Tat has to escape the degradation by endolysosomes. Because of findings that endolysosome de-acidification with, for example, the weak-base anti-malarial drug chloroquine prevents exogenous Tat degradation and enhances the amount of Tat available to activate HIV-1 LTR, we hypothesize that acidifying endolysosomes may enhance Tat degradation in endolysosomes and restrict LTR transactivation. Here, we determined the involvement of endolysosome-resident transient receptor potential mucolipin 1 channel (TRPML1) and the big conductance Ca2+-activated potassium (BK) channel in regulating endolysosome pH, as well as Tat-mediated HIV-1 LTR transactivation in U87MG cells stably integrated with HIV-1 LTR luciferase reporter. Activating TRPML1 channels with ML-SA1 acidified endolysosomes and restricted Tat-mediated HIV-1 LTR transactivation. These effects of ML-SA1 appeared to be mediated through activation of BK channels, because the effects of ML-SA1 on Tat-mediated HIV-1 LTR transactivation were blocked using pharmacological inhibitors or shRNA knock-down of BK channels. On the other hand, activating TRPML1 and BK channels enhanced cellular degradation of exogenous Tat. These results suggest that acidifying endolysosomes by activating TRPML1 or BK channels may provide therapeutic benefit against latent HIV-1 infection, HIV-1 associated neurocognitive disorders, and other HIV-1 comorbidities.
A novel fluorometric assay for trypsin on the basis of a gemini anionic surfactant/BSA/NR supramolecular assembly system with favorable salt resistance
Authors: Jia Lan , Yang Yufang , Liu Xiang , Chen Song , Zhu Jingxin
Published: August 2019

A novel label-free fluorometric assay for trypsin detection was successfully established on the basis of an anionic sulfonate gemini surfactant C12C3C12(SO3)2/bovine serum albumin (BSA)/nile red (NR) supramolecular assembly system.
Determination of phenol degradation in chloride ion rich water by ferrate using a chromatographic method in combination with on-line mass spectrometry analysis
Authors: Wu Debo , Xiong Yihan , He Minghe , Yang Shuiping , Cai Jialing , Wu Zhangxiong , Sun Shengpeng , Chen Xiaodong , Wu Winston Duo
Published: August 2019

On-line monitoring of phenol degradation in Cl−-rich water by Fe(vi) using EESI-MS.
Development of an immunochromatographic strip for the detection of rosiglitazone in functional foods based on monoclonal antibodies
Authors: Chen Yuxi , Liu Liqiang , Cui Gang , Wu Xiaoling , Kuang Hua , Xu Chuanlai
Published: August 2019

An anti-rosiglitazone (RSG) monoclonal antibody (4G6) was prepared to develop an immunochromatographic strip for the detection of illicitly added RSG in hypoglycemic functional foods.
All-inorganic perovskite/graphitic carbon nitride composites for CO2 photoreduction into C1 compounds under low concentrations of CO2
Authors: You Siqi , Guo Shaohong , Zhao Xue , Sun Min , Sun Chunyi , Su Zhongmin , Wang Xinlong
Published: August 2019

An all-inorganic perovskite (CsPbBr3) was introduced into g-C3N4 to fabricate the CsPbBr3@g-C3N4 photocatalyst for photochemical reduction in diluted CO2.
Post-imparting Brønsted acidity into an amino-functionalized MOF as a bifunctional luminescent turn-ON sensor for the detection of aluminum ions and lysine
Authors: Liu Yanhong , Huangfu Mengjie , Wu Pengyan , Jiang Min , Zhao Xiaoli , Liang Lili , Xie Liheng , Bai Jianguo , Wang Jian
Published: August 2019

A MOF with amino and Brønsted acid sites, exhibiting bifunctional luminescent turn-on sensing properties for the detection of Al3+and Lys.
Surface water treatment by UV/H2O2with subsequent soil aquifer treatment: impact on micropollutants, dissolved organic matter and biological activity
Authors: Wünsch Robin , Plattner Julia , Cayon David , Eugster Fabienne , Gebhardt Jens , Wülser Richard , von Gunten Urs , Wintgens Thomas
Published: August 2019

UV/H2O2treatment of sand-filtered surface water before soil aquifer treatment increases the total removal of organic micropollutants and has an impact on microbial activity without pronounced effects on dissolved organic matter removal.
The dietary freeze-dried fruit powder of Actinidia arguta ameliorates dextran sulphate sodium-induced ulcerative colitis in mice by inhibiting the activation of MAPKs
Authors: Lian Lian , Zhang Song , Yu Zhenlong , Ge Huiqi , Qi Shizhou , Zhang Xinxin , Long Liping , Xiong Xin , Chu Donghai , Ma Xiaochi , Li Xianzhe , Gao Huiyuan
Published: August 2019

Oral administration freeze-dried Actinidia arguta powder could ameliorate ulcerative colitis disease via inhibiting the activation of MAPKs pathway.
Spatially modulated stiffness on hydrogels for soft and stretchable integrated electronics
Authors: Liu Hao , Li Moxiao , Liu Shaobao , Jia Pengpeng , Guo Xiaojin , Feng Shangsheng , Lu Tian Jian , Yang Huayuan , Li Fei , Xu Feng
Published: August 2019

A versatile method for spatially modulating hydrogel stiffness was proposed. The locally stiffened hydrogel presented tunable strain-shielding ability and thus aided to electronic components integration for wearable electronics.
Laser additive nano-manufacturing under ambient conditions
Authors: Zhao Chenglong , Shah Piyush J. , Bissell Luke J.
Published: August 2019

A review of state-of-the-art additive nano-manufacturing with lasers under ambient conditions.
Efficient and stable perovskite solar cells based on perfluorinated polymers
Authors: Valero Silvia , Soria Tomás , Marinova Nevena , Delgado Juan Luis
Published: August 2019

Novel perfluorinated semiconductor compounds were introduced into the perovskite layer as additives and stable and efficient perovskite-based devices were achieved.
Grignard synthesis of fluorinated nanoporous element organic frameworks based on the heteroatoms P, B, Si, Sn and Ge
Authors: Kann Anna , Krüger Andreas J. D. , Rose Marcus , Hausoul Peter J. C.
Published: August 2019

We present the synthesis and characterization of fluorinated polymers based on P, B, Si, Sn and Ge as heteroatomsviaGrignard activation.
Residual strain effects in needle-induced cavitation
Authors: Barney Christopher W. , Zheng Yue , Wu Shuai , Cai Shengqiang , Crosby Alfred J.
Published: August 2019

Needle-induced cavitation (NIC) locally probes the elastic and fracture properties of soft materials, such as gels and biological tissues.
Exploring the catalytic performance of a series of bimetallic MIL-100(Fe, Ni) MOFs
Authors: Giménez-Marqués Mónica , Santiago-Portillo Andrea , Navalón Sergio , Álvaro Mercedes , Briois Valérie , Nouar Farid , Garcia Hermenegildo , Serre Christian
Published: August 2019

Stable mixed-metal FeIII/NiII MIL-100 MOFs have been synthesized de novo and have been explored as superior heterogeneous catalysts in acid catalyzed reactions, presenting superior performances.
Insights into charge storage and electroactivation of mixed metal sulfides in alkaline media: NiCoMn ternary metal sulfide nano-needles forming core–shell structures for hybrid energy storage
Authors: Sanchez Jaime S. , Pendashteh Afshin , Palma Jesus , Anderson Marc , Marcilla Rebeca
Published: August 2019

NiCoMnS2 were subjected to ex situ/operando measurements, shedding light on energy storage mechanism and electroactivation of mixed sulfides in alkaline media.
Lithiophilic Ag/Li composite anodes via a spontaneous reaction for Li nucleation with a reduced barrier
Authors: Liu Tiancheng , Hu Qiyang , Li Xinhai , Tan Lei , Yan Guochun , Wang Zhixing , Guo Huajun , Liu Yong , Wu Yuping , Wang Jiexi
Published: August 2019

Lithiophilic silver/lithium composite anodes are synthesized via a spontaneous displacement reaction to settle the problems of lithium metal anodes by regulating Li nucleation and homogenizing Li-ion flux.
Modulating the molecular packing and distribution enables fullerene-free ternary organic solar cells with high efficiency and long shelf-life
Authors: Du Xiaoyang , Zhao Juewen , Zhang Hao , Lu Xi , Zhou Lei , Chen Zhenhua , Lin Hui , Zheng Caijun , Tao Silu
Published: August 2019

Novel hydrogen-bond based ternary strategy endows organic solar cells with high efficiency and excellent shelf-lifeviamodulating the crystallization and aggregation of nonfullerene acceptors.
Vocabulary Growth From 18 to 24 Months of Age in Children With and Without Repaired Cleft Palate
Authors: Eshghi Marziye , Adatorwovor Reuben , Preisser John S. , Crais Elizabeth R. , Zajac David J.
Published: August 2019

Purpose

This study investigated vocabulary growth from 18 to 24 months of age in young children with repaired cleft palate (CP), children with otitis media, and typically developing (TD) children. In addition, the contributions of factors such as hearing level, middle ear status, size of consonant inventory, maternal education level, and gender to the development of expressive vocabulary were explored.

Method

Vocabulary size of 40 children with repaired CP, 29 children with otitis media, and 25 TD children was measured using the parent report on MacArthur–Bates Communicative Development Inventories: Words and Sentences (Fenson et al., 2007) at 18 and 24 months of age. All participants underwent sound field audiometry at 12 months of age and tympanometry at 18 months of age. A multiple linear regression with and without covariates was used to model vocabulary growth from 18 to 24 months of age across the 3 groups.

Results

Children with CP produced a significantly smaller number of words at 24 months of age and showed significantly slower rate of vocabulary growth from 18 to 24 months of age when compared to TD children (p< .05). Although middle ear status was found to predict vocabulary growth from 18 to 24 months of age across the 3 groups (p< .05), the confidence interval was large, suggesting the effect should be interpreted with caution.

Conclusions

Children with CP showed slower expressive vocabulary growth relative to their age-matched TD peers. Middle ear status may be associated with development of vocabulary skills for some children.
Leaderless cooperative control of robotic sensor networks for monitoring dynamic pollutant plumes
Authors: Wang Jun‐Wei , Guo Yi
Published: August 2019

In this paper, the problem of cooperative control of robotic sensor networks (RSNs) for monitoring dynamic pollutant plumes in two‐dimensional (2D) space is studied. The pollutant plume propagation dynamics is governed by a 2D advection‐diffusion partial differential equation (PDE), and the plume front is modelled by a level set with a pre‐specified threshold value. Distributed consensus Luenberger‐type PDE observers are first constructed using local concentration measurements from the RSNs for unanimous estimate of the dynamic concentration field over the entire spatial domain. With the aid of the distributed consensus observers, a leaderless cooperative control scheme is then developed for the RSNs to monitor the dynamic plume front expansion. It is proved using the Lyapunov stability method and set stability concept that the proposed cooperative control scheme guarantees tracking of the dynamic plume front expansion and coverage of the plume front. Extensive numerical simulation results demonstrate the effectiveness and merit of the proposed cooperative control scheme.
Fuzzy gear shifting control optimisation to improve vehicle performance, fuel consumption and engine emissions
Authors: Eckert Jony Javorski , Santiciolli Fabio M. , Yamashita Rodrigo Y. , Corrêa Fernanda C. , Silva Ludmila C.A. , Dedini Franco G.
Published: August 2019

This study presents a multiobjective optimisation applied to the gear shifting fuzzy control of a vehicle equipped with an automated manual transmission (AMT), aiming to improve acceleration performance and reduce engine fuel consumption and emissions. An Adaptive‐Weight Genetic Algorithm was employed to find optimum fuzzy membership functions, according to the input and output ranges, and also optimum control rules with their respective weights. The vehicle behaviour is represented by longitudinal dynamics simulations developed in Simulink/Matlab™ interface, associated with the ADVISOR™ fuel converter block, that provides the engine emissions and fuel consumption. These simulations were based on the FTP‐75 emissions test procedure, that considers cold and hot phases of the driving cycle evaluating the engine transient operation as a function of the catalyst efficiency during the warm‐up period. The optimum fuzzy control with the best trade‐off among the optimisation criteria presented 19.72% fuel saving associated with 12.90% hydrocarbon, 29.20% carbon monoxide and 17.02% nitrogen oxides emissions reduction and an acceleration performance improvement when compared to a standard gear shifting procedure for a manual controlled gearbox. Moreover, the optimised fuzzy gear shifting control, improves the relationship between fuel consumption and emissions significantly, when compared to another optimum AMT control based on speed limits only.
Isolated high step‐up switched‐boost DC/DC converter with modified control method
Authors: Aghdam Meinagh Farhad Abbasi , Babaei Ebrahim , Tarzamni Hadi , Kolahian Pouya
Published: August 2019

In this study, a new isolated high‐gain switched‐boost DC/DC converter employing two symmetrical switched‐boost networks along with a modified control algorithm based on the combination of the pulse‐width modulation (PWM) and phase‐shift modulation is proposed. Utilising symmetrical switched‐boost networks increase the voltage gain of the proposed converter, significantly. Moreover, applying the proposed switching algorithm on the proposed isolated switched‐boost DC/DC converter leads to the following advantages: (i) high‐voltage gain, (ii) zero voltage switching (ZVS) turn‐on of two switches, (iii) ZVS turn‐off of two switches and (iv) appearing three controllable parameters (the shoot‐through duty cycle, the phase shift and the transformer turns ratio) in all of the equations including the voltage gain equation, which enhances the flexibility of the converter. In this study, the steady‐state analysis, design procedure of the elements, and voltage and current stress of the semiconductors are given. Then, the proposed converter and the proposed switching algorithm are compared with similar converters and modulation techniques in order to highlight their features and drawbacks. Finally, experimental results are obtained to substantiate the theoretical analysis accuracy.
Switched capacitor based Z‐source DC–DC converter
Authors: Rostami Sajad , Abbasi Vahid , Kerekes Tamas
Published: August 2019

This study proposes a common grounded Z‐source DC–DC converter. In comparison to conventional Z‐source converter, it converts voltage with higher voltage gain and lower voltage stress on the switch, diodes and capacitors. In addition, it needs smaller inductors in comparison to the similar converters. The converter is analysed and compared with other converters. Its main equations are obtained which show the converter advantages as lower voltage stresses, smaller inductors, higher efficiency and higher voltage gain in comparison to the reviewed converters. A prototype for the proposed converter is prepared based on analysis and theoretical parts. Experiments are done along the lines of the analysis. Experimental results and theoretical equations are used to prove the converter operation quality.
Modifications on parametric models for distributed scattering centres on surfaces with arbitrary shapes
Authors: Zhao Xiao‐Tong , Guo Kun‐Yi , Sheng Xin‐Qing
Published: August 2019

Distributed scattering centre (DSC) is a particular type of scattering centres which has the strongest scattering amplitude among all scattering centres. Furthermore, their distributed signatures in radar images have directly shown geometries of targets. Therefore, DSCs play an important role in target recognition. DSCs are currently described by the attributed scattering centre (ASC) model, which is developed out of the asymptotic expansion solutions to canonical geometries. However, rather than canonical geometries, real radar targets have various geometric structures, which show different signatures in radar images. In order to characterise these various signatures, the parametric model is modified. Scattered fields from planar and single‐curved surfaces with arbitrary shapes are studied in this study and motivated by which, the parametric models of DSCs for more general structures are presented. To validate these models, the scattered waves and the post‐imaging results simulated by these models are compared with those obtained by a rigorous full‐wave numerical method, and those obtained by the conventional ASC model. The comparison results demonstrate these models have a higher accuracy over the conventional model in simulations of scattered waves, as well as inverse synthetic aperture radar image signatures of different geometric structures.
Hierarchical coastline detection in SAR images based on spectral‐textural features and global–local information
Authors: Modava Mohammad , Akbarizadeh Gholamreza , Soroosh Mohammad
Published: August 2019

This study presents a novel approach to detect the coastline from single‐polarisation synthetic aperture radar (SAR) images. The proposed method encompasses land/sea segmentation, coastline detection, and refinement. A novel spectral–textural segmentation framework (STSF) is proposed by using the spectral–textural features extracted from the input image patches. The STSF distinguishes various coastal/sea types and is robust to noise. Also, a hierarchical region‐based level set method (LSM) is proposed to detect the coastline, accurately. The first LSM step applies global information for evolution. The LSM initialisation is performed using the obtained rough segmentation, which is very practical as the final LSM evolution depends on the initial value, particularly on complex SAR images. The global region‐based LSM (GRB‐LSM) step modifies the previous segmentation and approaches to the coastline. To improve accuracy, a local region‐based LSM (LRB‐LSM) is proposed. Therefore, in the second LSM step, the LRB‐LSM applies to the results of GRB‐LSM step. The LRB‐LSM improves the accuracy of the detected coastline while ensuring its smoothness. To verify the performance of the proposed method, several high‐resolution SAR images from different microwave bands and various coastal environments are used. The performance of the proposed method is confirmed by the given experiments.
Modelling and simulation of chlorophyll fluorescence from PSII of a plant leaf as affected by both illumination light intensities and temperatures
Authors: Fu Lijiang , Xia Qian , Tan Jinglu , Wu Hao , Guo Ya
Published: August 2019

The emission of chlorophyll fluorescence (ChlF) from photosystem II (PSII) of plant leaves the couple with photoelectron transduction cascades in photosynthetic reactions and can be used to probe photosynthetic efficiency and plant physiology. Because of population increase, food shortages, and global warming, it is becoming more and more urgent to enhance plant photosynthesis efficiency by controlling plant growth rate. An effective model structure is essential for plant control strategy development. However, there is a lack of reporting on modelling and simulation of PSII activities under the interaction of both illumination light intensities and temperatures, which are the two important controllable factors affecting, plant growth, especially for a greenhouse. In this work, the authors extended their work on modelling photosynthetic activities as affected by light and temperature to cover both the interaction effects of illumination light intensities and temperature on ChlF emission. Experiments on ChlF were performed under different light intensities and temperatures and used to validate the developed model structure. The average relative error between experimental data and model fitting is <0.3%, which shows the effectiveness of the developed model structure. Simulations were performed to show the interaction effect of light and temperature effects on photosynthetic activities.
Dynamic simulation of a combined cycle for power plant flexibility enhancement
Authors: Reveillere Adrien , Longeon Martin , Rossi Iacopo
Published: August 2019

System simulation is used in many fields to help design, control or troubleshoot various industrial systems. Within the PUMP-HEAT H2020 project, it is applied to a combined cycles power plant, with innovative layouts that include heat pumps and thermal storage to un-tap combined cycle potential flexibility through low-CAPEX balance of plant innovations. Simcenter Amesim software is used to create dynamic models of all subsystems and their interactions and validate them from real life data for various purpose. Simple models of the Gas Turbine (GT), the Steam loop, the Heat Recovery Steam Generator (HRSG), the Heat Pump and the Thermal Energy storage with Phase Change material are created for Pre-Design and concept validation and then scaled to more precise design. Control software and hardware is validated by interfacing them with detailed models of the virtual plant by Model in the Loop (MiL), Software in the Loop (SiL) and Hardware in the Loop (HiL) technologies. Unforeseen steady state and transient behaviours of the powerplant can be virtually captured, analysed, understood and solved. The purpose of this paper is to introduce the associated methodologies applied in the PUMP-HEAT H2020 project and their respective results.
Compressor Retrofittable Solutions in Heavy-Duty Gas Turbines for Minimum Environmental Load Reduction
Authors: Mosele Stefano Gino , Garbarino Tiziano , Schneider Andrea , Cozzi Lorenzo , Arnone Andrea , Goinis Georgios , Hedkvist Simon
Published: August 2019

International policies aiming at keeping global warming within safety limits will strongly impact gas-fired power plants. Flexibility is going to be the key-word, hence this paper focuses on possible strategies to increase turndown capability (i.e. lowering Minimum Environmental Load (MEL)) of open and combined cycle power plants (CCPP) through retrofittable compressor service packages. In particular, the following three options have been analyzed: extra-closure of Variable Inlet Guide Vanes (IGVs), Blow-Off (BO) lines opening and inlet bleed heating. All these solutions aim at reducing the compressor outlet mass-flow rate while keeping a safe stability margin. The effect of lowering the minimum load capability by opening the BO lines has been numerically investigated through full compressor 2D throughflow analyses. Moreover, the impact on compressor performance and stability of the extra-closure of IGVs has been analyzed with the support of 3D steady-state CFD modelling. Finally, the overall performance of the power-plant has been included and discussed in order to provide plant managers with a solid starting point for a techno-economic analysis.
Thermodynamic and economic analysis of a plant for the CO2 hydrogenation for methanol production
Authors: Bellotti Daria , Dierks Matthias , Moellenbruck Florian , Magistri Loredana , Görner Klaus , Oeljeklaus Gerd
Published: August 2019

A major goal of politics, society, and industry is the reduction of carbon dioxide (CO2) emissions in order to prevent anthropogenic climate change and an increase in earth’s temperature. In addition, the expansion of renewable energies and the use of nuclear power, CO2 capturing (e.g. from exhaust gases), is regarded as a promising strategy to reduce global CO2 emissions. In this context, the Power-to-X technologies can provide an innovative energy storage concept by combining the main trends of energy systems aiming at high shares of renewable energies, reduction of CO2 emissions and sector coupling. A promising approach is the production of methanol as a chemical raw material or fuel. The goal of this paper is to present (i) an extensive thermodynamic analysis for the methanol production from carbon dioxide and hydrogen and (ii) an economic analysis for the process based on the thermodynamic studies. The thermodynamic analysis was carried out in the simulation tool Aspen Plus™ in order to investigate the impact of the operating temperature and pressure on the performance of the synthesis unit. Based on the thermodynamic results, an economic analysis has been performed in order to define the most feasible solution. For a defined optimal operating temperature, the fixed and operating costs and the methanol production cost were evaluated for different operating pressures. Finally, a sensitivity analysis has been performed in order to define the minimum methanol selling price that allows for a payback period of 10 years for different values of the electrical energy purchasing price.
Packed-bed sensible thermal energy storage system using demolition wastes for concentrated solar power plants
Authors: Koçak Burcu , Paksoy Halime
Published: August 2019

This paper presents a study on development of a packed-bed storage system for CSP applications. In this system, demolition wastes from urban regeneration projects in Turkey has been investigated as potential STESM for cost effective storage systems. Schumann’s two-phase one-dimensional model was used to evaluate the optimal design parameters. Effect of operational and geometrical design parameters such as mass velocity, porosity, aspect ratio of packed bed, packing diameter were assessed on storage performance. The system showed the best performance with low bed void fraction, low mass flow rate and low Rep.
Test Rig for Emulation of Turbocharged SOFC Plants
Authors: Ferrari Mario L. , Pascenti Matteo , Abrassi Alessio
Published: August 2019

This work is devoted to an emulator test rig designed for experimental analysis on SOFC-based plants pressurised by a turbocharger. The utilization of a turbocharger for SOFC pressurization aims to reduce the machine costs, due to the large mass production of this component. This emulator rig is an essential plant to perform tests on the component integration, dynamic operations, control system development and prevention of risky operative conditions (e.g. surge). These are essential issues to be solved before developing expensive complete prototypes and the related commercialization. This experimental plant is based on a pressure vessel for emulating the thermal (combustor and inert ceramic material) and fluid dynamic (the volume) responses. The vessel pressurisation is obtained with a turbocharger, where the exhaust flow operating in the turbine powers the compressor. The plant is also equipped with a recuperator and with different valves for control and flexibility reasons (bleed, compressor/turbine bypass, and recuperator bypass). Preliminary experimental results are included in this work focusing attention on the turbocharger choice and on the component constraints. In details, these are the necessary experiments for choosing the suitable machine for the rig (with a good surge margin for this component coupling).
Microturbine-Based Test Rig for Emulation of SOFC Hybrid Systems
Authors: Ferrari Mario L. , Pascenti Matteo , Massardo Aristide F.
Published: August 2019

This work is devoted to an emulator test rig based on a T100 microturbine (100 kW electric power) and designed for SOFC hybrid systems. Since this facility does not include a real fuel cell, it is mainly used for tests on the SOFC/T100 integration to analyse possible stress and risky operations (e.g. surge) especially in dynamic conditions. The tests performed with this rig range from component analysis, to experimental studies at dynamic conditions and surge risk analysis.
Dynamic Effect of Cold-Air Bypass Valve for Compressor Surge Recovery and Prevention in Fuel Cell Gas Turbine Hybrid Systems
Authors: Mantelli Luca , Tucker David , Ferrari Mario Luigi
Published: August 2019

A large volume between compressor and turbine is present in fuel cell gas turbine hybrid systems. The substantially larger compressor plenum volume modifies the dynamic behaviour of these systems, increasing the risk of compressor surge during transients and subsequent destruction of both turbomachinery and fuel cell components. Diverting part of the compressor inlet flow directly to the turbine inlet through a cold-air bypass valve, bypassing the fuel cell stack, has been proven to be an effective method to increase the surge margin during normal operation and also to recover the machine from fully developed surge. This study investigates the dynamic effect of different cold-air bypass valve opening/closing procedures, especially steps and ramps changing the valve fractional opening. This analysis was carried out with reference to the Hybrid Performance (Hyper) facility: a hybrid system emulated using hardware and a cyber-physical fuel cell system at the National Energy Technology Laboratory (NETL), U.S. Department of Energy (DOE). Simulations performed on a Matlab®-Simulink® dynamic model of the system based on Greitzer’s theory showed a different behaviour varying the valve fractional opening with steps or ramps. Many experimental tests were performed on the Hyper facility to confirm the trends obtained from the simulations results. From the outcomes of this study, it has been possible to determine how to maximize the surge recovery effect of the cold-air bypass valve opening and to minimize surge related risks during the valve closure.
Advanced energy management system based on PV and load forecasting for load smoothing and optimized peak shaving of islanded power systems
Authors: Iliadis Petros , Domalis Stefanos , Nesiadis Athanasios , Atsonios Konstantinos , Chapaloglou Spyridon , Nikolopoulos Nikos , Grammelis Panagiotis
Published: August 2019

Photovoltaic (PV) systems constitute one of the most promising renewable energy sources, especially for warm and sunny regions like the southern-European islands. In such isolated systems, it is important to utilize clean energy in an optimal way in order to achieve high renewable penetration.

In this operational strategy, a Battery Energy Storage System (BESS) is most often used to transfer an amount of the stored renewable energy to the peak hours. This study presents an integrated energy management methodology for a PV-BESS energy system targeting to make the load curve of the conventional fuel based units as smooth as possible. The presented methodology includes prediction modules for short-term load and PV production forecasting using artificial neural, and a novel, optimized peak shaving algorithm capable of performing each day’s maximum amount of peak shaving and smoothing level simultaneously.

The algorithm is coupled with the overall system model in the Modelica environment, on the basis of which dynamic simulations are performed. The simulation results are compared with the previous version of the algorithm that had been developed in CERTH, and it is revealed that the system’s performance is drastically improved. The overall approach proves that in such islanding systems, a PV-BESS is a suitable option to flatten the load of the conventional fuel based units, achieve steadier operation and increase the share of renewable energy penetration to the grid.
Modelling phase change in a novel turbo expander for application to heat pumps and refrigeration cycles
Authors: Engelbrecht E. Geoffrey , Giakoumis Zoitis , Sidiropoulos Stathis , Chasoglou Alexandros , Chokani Ndaona
Published: August 2019

A novel turbo expander based on the Tesla turbine is proposed to be applied to a heat pump or refrigeration cycle to improve the overall cycle efficiency. Initial numerical modelling of this turbo expander at representative conditions was carried out using the homogeneous relaxation model (HRM) to assess the influence of phase change on performance. The presence of a dense cloud of liquid droplets within the rotor was predicted to produce a significant back pressure on the turbine nozzle postponing the phase change. This was expected to occur in the vicinity at the outlet of the nozzle, but high volume fractions of liquid was predicted to penetrate deeper inside the rotor, especially at higher RPM. The resulting lower velocities of the liquid flow at the inlet of the rotor was predicted to significantly degrades the performance of the turbine. It is thus important for a successful implementation of this concept to remove as much liquid droplets as possible before the flow enters the rotor in order to minimise the back pressure.