bluuebunny/crossref_metadata_2025 huggingface dataset:
Acyl chain shortening induced by inhibition of acetyl-CoA carboxylase renders phosphatidylcholine redundant
Authors: Bao Xue , Koorengevel Martijn C. , Koerkamp Marian J.A. Groot , Homavar Amir , Weijn Amrah , Crielaard Stefan , Renne Mike F. , Geerts Willie J.C. , Surma Michal A. , Mari Muriel , Holstege Frank C.P. , Klose Christian , Kroon Anton I.P.M. de
Published: February 2021

Phosphatidylcholine (PC) is an abundant membrane lipid component in most eukaryotes including yeast. PC has been assigned a multitude of functions in addition to that of building block of the lipid bilayer. Here we show that PC is evolvable essential in yeast by isolating suppressor mutants devoid of PC that exhibit robust growth. The requirement for PC is suppressed by monosomy of chromosome XV, or by a point mutation in theACC1gene encoding acetyl-CoA carboxylase. Although these two genetic adaptations rewire lipid biosynthesis differently, both decrease Acc1 activity thereby reducing the average acyl chain length. Accordingly, soraphen A, a specific inhibitor of Acc1, rescues a yeast mutant with deficient PC synthesis. In the aneuploid suppressor, up-regulation of lipid synthesis is instrumental to accomplish feed-back inhibition of Acc1 by acyl-CoA produced by the fatty acid synthase (FAS). The results show that yeast regulates acyl chain length by fine-tuning the activities of Acc1 and FAS, and indicate that PC evolved by benefitting the maintenance of membrane fluidity.
The role of arbuscular mycorrhiza and organosulfur mobilizing bacteria in plant sulphur supply
Authors: Gahan Jacinta , O’Sullivan Orla , Cotter Paul , Schmalenberger Achim
Published: February 2021

AM fungi are enhancing growth and health of many land plants but only some of these beneficial mechanisms are well understood. This study aimed to uncover the role of bacteria colonising AM fungi in organically-bound sulfur (S) mobilisation, the dominant S pools in soil that are not directly available to plants. The effect of an intact AM symbiosis with access to stable isotope organo-34S enriched soils encased in 35 µm mesh cores was tested in microcosms withAgrostis stoloniferaandPlantago lanceolata. At 3 month intervals, the plant shoots were analysed for34S uptake. After 9 months, hyphae and associated soil was picked from static (mycorrhizal) and rotating (severed hyphae) mesh cores and corresponding rhizosphere soil was sampled for bacterial analysis. AM symbiosis increased uptake of34S from organo-34S enriched soil at early stages of plant growth when S demand appeared to be high. The static (mycorrhizal) treatments were shown to harbour larger populations of cultivable heterotrophs and sulfonate mobilising bacteria. Microbial communities were significantly different in the hyphosphere of mycorrhizal hyphae and hyphae not associated to plant hosts. Sulfate ester (arylsulfatase enzyme assay,atsAgene) and sulfonate mobilising activity (asfAgene) was altered by an intact AM symbiotic partnership which stimulated the generaAzospirillum, BurkholderiaandPolaromonas. Illumina sequencing revealed that AM symbiosis led to community shifts, reduced diversity and dominance of the Planctomycetes and Proteobacteria. This study demonstrated that AM symbioses can promote organo-S mobilization and plant uptake through interaction with hyphospheric bacteria.

Research highlights

AM hyphae enhanced uptake of organically bound34S at early stages of growth.

AM hyphosphere harboured a large population of organo-S desulfurizing bacteria.

Microbial communities significantly differed in rotating and static mesh cores.

AM hyphae influenced bacterial sulfate ester and sulfonate mobilising activity.

AM hyphae reduced bacterial diversity, increased Planctomycetes and Proteobacteria abundance.
Pkd1mutation has no apparent effects on peroxisome structure or lipid metabolism
Authors: Terabayashi Takeshi , Menezes Luis F , Zhou Fang , Cai Hongyi , Walter Peter J , Garraffo Hugo M , Germino Gregory G
Published: February 2021

Background

Multiple studies of tissue and cell samples from patients and pre-clinical models of autosomal dominant polycystic kidney disease report abnormal mitochondrial function and morphology and suggest metabolic reprogramming is an intrinsic feature of this disease. Peroxisomes interact with mitochondria physically and functionally, and congenital peroxisome biogenesis disorders can cause various phenotypes, including mitochondrial defects, metabolic abnormalities and renal cysts. We hypothesized that a peroxisomal defect might contribute to the metabolic and mitochondrial impairments observed in autosomal dominant polycystic kidney disease.

Methods

Using control andPkd1-/-kidney epithelial cells, we investigated peroxisome abundance, biogenesis and morphology by immunoblotting, immunofluorescent and live cell imaging of peroxisome-related proteins and assayed peroxisomal specific β-oxidation. We further analyzed fatty acid composition by mass spectrometry in kidneys ofPkd1fl/fl;Ksp-Cremice. We also evaluated peroxisome lipid metabolism in published metabolomics datasets ofPkd1mutant cells and kidneys. Lastly, we investigated if the C-terminus or full-length polycystin-1 co-localize with peroxisome markers by imaging studies.

Results

Peroxisome abundance, morphology and peroxisome-related protein expression inPkd1-/-cells were normal, suggesting preserved peroxisome biogenesis. Peroxisomal β-oxidation was not impaired inPkd1-/-cells, and there was no obvious accumulation of very long chain fatty acids in kidneys of mutant mice. Re-analysis of published datasets provide little evidence of peroxisomal abnormalities in independent sets ofPkd1mutant cells and cystic kidneys, while providing further evidence of mitochondrial fatty acid oxidation defects. Imaging studies with either full length polycystin-1 or its C-terminus, a fragment previously shown to go to the mitochondria, showed minimal co-localization with peroxisome markers.

Conclusions

Our studies showed that loss ofPkd1does not disrupt peroxisome biogenesis nor peroxisome-dependent fatty acid metabolism.

Key points

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While mitochondrial abnormalities and fatty acid oxidation impairment have been reported in ADPKD, no studies have investigated if peroxisome dysfunction contributes to these defects.

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We investigated peroxisome morphology, biogenesis and function in cell and animal models of ADPKD and investigated whether polycystin-1 co-localized with peroxisome proteins.

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Our studies show that loss ofPkd1does not disrupt peroxisome biogenesis nor peroxisome-dependent fatty acid metabolism.
Molecular evolutionary dynamics of energy limited microorganisms
Authors: Shoemaker William R. , Polezhaeva Evgeniya , Givens Kenzie B. , Lennon Jay T.
Published: February 2021

Microorganisms have the unique ability to survive extended periods of time in environments with extremely low levels of exploitable energy. To determine the extent that energy limitation affects microbial evolution, we examined the molecular evolutionary dynamics of a phylogenetically diverse set of taxa over the course of 1,000-days. We found that periodic exposure to energy limitation affected the rate of molecular evolution, the accumulation of genetic diversity, and the rate of extinction. We then determined the degree that energy limitation affected the spectrum of mutations as well as the direction of evolution at the gene level. Our results suggest that the initial depletion of energy altered the direction and rate of molecular evolution within each taxon, though after the initial depletion the rate and direction did not substantially change. However, this consistent pattern became diminished when comparisons were performed across phylogenetically distant taxa, suggesting that while the dynamics of molecular evolution under energy limitation are highly generalizable across the microbial tree of life, the targets of adaptation are specific to a given taxon.
O-GlcNAc regulates MTA1 transcriptional activity during breast cancer cells genotoxic adaptation
Authors: Xie Xueqin , Wu Qiutong , Zhang Keren , Liu Yimin , Zhang Nana , Chen Qiushi , Wang Lingyan , Li Wenli , Zhang Jianing , Liu Yubo
Published: February 2021

Chromatin modifier metastasis-associated protein 1 (MTA1), closely correlated with the development and progression in breast cancer, has a vital role in multiple cellular processes, including gene expression and cell homeostasis. Although MTA1 is a stress-responsive gene, its role in genotoxic adaptation remains unexplored. The current study sought to investigate the role of MTA1 and its O-GlcNAc modification in breast cancer cells genotoxic adaptation by using quantitative proteomics, ChIP-seq, transcriptome analysis, loss-and gain-of-functions experiments. We demonstrate that O-GlcNAc modification promotes MTA1 to interact with chromatin and regulates target gene expression, contributing to breast cancer cell genotoxic adaptation. MTA1 is modified with O-GlcNAc residues at serine 237/241/246 in adriamycin adaptive breast cancer cells and that modification improves the genome-wide interactions of MTA1 with gene promotor regions by enhancing its association with nucleosome remodeling and histone deacetylation (NuRD) complex. Further, O-GlcNAc-modulated MTA1 chromatin-binding influences the specific transcriptional regulation of genes involved in the adaptation of breast cancer cells to genotoxic stress. Our findings reveal a previously unrecognized role of O-GlcNAc MTA1 in transcriptional regulation and suggest that O-GlcNAc modification is a promising therapeutic target to overcome chemoresistance in breast cancers.
Cover crop residue diversity enhances microbial activity and biomass with additive effects on microbial structure
Authors: Shu Xin , Zou Yiran , Shaw Liz J. , Todman Lindsay , Tibbett Mark , Sizmur Tom
Published: February 2021

Cover crops have been widely used in agroecosystems to improve soil fertility and environmental sustainability. The decomposition of cover crop residues can have further effects on belowground communities and their activity, which is important for a series of soil functions (e.g., nutrient cycling and organic matter decomposition). We tested the effect of plant residues from a range of cover crop species on soil microbial activity and community assemblage. We predicted that cover crop residues would alter the soil microbial community and that a greater diversity of residues would enhance microbial decomposition. In an incubation study, we assessed the effect of crop residue diversity on microbial activity (soil respiration) and its consequent effects on microbial community composition (PLFA). We used either a biodiverse mixture of four cover crop residues (buckwheat, clover, sunflower and radish) or an equal mass of the residues of each of the individual species. The diverse mixture of cover crop residues had a significantly (P< 0.05) greater soil respiration rate, by 57.61 µg C g−1h−1, than the average of the four individual residues, but did not have a significantly different soil microbial biomass or microbial community structure. This finding could be attributed to a greater diversity of organic resources increasing the number biochemical niches, and hence activating dormant microbial communities to increase microbial activity without affecting microbial biomass or community composition. Greater respiration from similar microbial biomasses suggests that microbial activity might be more efficient after a more diverse substrate input. This study confirms the positive impact of cover crop residues on soil microbial biomass and activity and highlights that mixtures of cover crop residues may deliver enhanced soil functions beyond the sum of individual cover crop residues.
Rare long-range cortical connections enhance information processing
Authors: Deco Gustavo , Perl Yonathan Sanz , Vuust Peter , Tagliazucchi Enzo , Kennedy Henry , Kringelbach Morten L.
Published: February 2021

What are the key topological features of connectivity critically relevant for generating the dynamics underlying efficient cortical function? A candidate feature that has recently emerged is that the connectivity of the mammalian cortex follows an exponential distance rule, which includes a small proportion of long-range high-weight anatomical exceptions to this rule. Whole-brain modelling of large-scale human neuroimaging data in 1003 participants offers the unique opportunity to create two models with and without long-range exceptions and explicitly study their functional consequences. We found that rare long-range exceptions are crucial for significantly improving information processing. Furthermore, modelling in a simplified ring architecture shows that this improvement is greatly enhanced by the turbulent regime found in empirical neuroimaging data. Overall, the results provide strong empirical evidence for the immense functional benefits of long-range exceptions combined with turbulence for information processing.
Sensory experience modulates the reorganisation of temporal auditory regions for executive processing
Authors: Manini Barbara , Vinogradova Valeria , Woll Bencie , Cameron Donnie , Eimer Martin , Cardin Velia
Published: February 2021

Crossmodal plasticity refers to the reorganisation of sensory cortices in the absence of their main sensory input. Understanding this phenomenon provides insights into brain function and its potential for change and enhancement. Using fMRI, we investigated how early deafness influences crossmodal plasticity and the organisation of executive functions in the adult human brain. Results from a range of visual executive function tasks (working memory, task switching, planning, inhibition) show that deaf individuals specifically recruit “auditory” regions during task switching. Neural activity in superior temporal regions, most significantly in the right hemisphere, are good predictors of behavioural performance during task switching in the deaf group, highlighting the functional relevance of the observed cortical reorganisation. Our results show executive processing in typically sensory regions, suggesting that the development and ultimate role of brain regions are influenced by perceptual environmental experience.
Genome-wide CRISPR interference screen identifies long non-coding RNA loci required for differentiation and pluripotency
Authors: Haswell Jeffrey R. , Mattioli Kaia , Gerhardinger Chiara , Maass Philipp G. , Foster Daniel J. , Fernandez Paola P. , Wang Xiaofeng , Rinn John L. , Slack Frank J.
Published: February 2021

Although many long non-coding RNAs (lncRNAs) exhibit lineage-specific expression, the vast majority remain functionally uncharacterized in the context of development. Here, we report the first described human embryonic stem cell (hESC) lines to repress (CRISPRi) or activate (CRISPRa) transcription during differentiation into all three germ layers, facilitating the modulation of lncRNA expression during early development. We performed an unbiased, genome-wide CRISPRi screen targeting thousands of lncRNA loci expressed during endoderm differentiation. While dozens of lncRNA loci were required for proper differentiation, most differentially expressed lncRNAs were not, supporting the necessity for functional screening instead of relying solely on gene expression analyses. In parallel, we developed a clustering approach to infer mechanisms of action of lncRNA hits based on a variety of genomic features. We subsequently identified and validated FOXD3-AS1 as a functional lncRNA essential for pluripotency and differentiation. Taken together, the cell lines and methodology described herein can be adapted to discover and characterize novel regulators of differentiation into any lineage.
Molecular Mechanism of Capsid Disassembly in Hepatitis B Virus
Authors: Ghaemi Zhaleh , Gruebele Martin , Tajkhorshid Emad
Published: February 2021

The disassembly of a viral capsid leading to the release of its genetic material into the host cell is a fundamental step in viral infection. Hepatitis B virus (HBV) in particular consists of identical capsid protein monomers that dimerize and also arrange themselves into pentamers or hexamers on the capsid surface. By applying atomistic molecular dynamics simulation to an entire solvated HBV capsid subject to a uniform mechanical stress protocol, we monitor the disassembly process down to the level of individual amino acids. The strain of an external force combined with thermal fluctuations causes structurally heterogeneous cracks to appear in the HBV capsid. Unlike the expectation from purely mechanical considerations, the cracks mainly occur within and between hexameric sites, whereas pentameric sites remain largely intact. Only a small subset of the capsid protein monomers governs disassembly. These monomers are distributed across the whole capsid, but belong to regions with a high degree of collective motion that we label ‘communities’. Cross-talk within these communities is a mechanism of crack propagation leading to destabilization of the entire capsid, and eventually its disassembly. We identify specific residues whose interactions are most readily lost during disassembly: R127, I139, Y132, N136, A137, and V149 are among the hotspots at the interfaces between dimers that lie within or span hexamers, leading to dissociation. The majority of these hotspots are evolutionary conserved, indicating that they are important for disassembly by avoiding over-stabilization of capsids.

Significance

Hepatitis B virus (HBV) is a DNA virus that is 100 times more infectious than HIV. Despite the availability of a vaccine, the chronic infection rate of this virus is still about 300 million people globally. HBV chronic infection, for which no cure is currently available, can lead to liver cancer. Therefore, there is an unmet need to investigate the infection cycle of the virus. One of the most crucial steps in virus replication cycle is the release of its genetic material to the nucleus. During this step, the viral capsid enclosing the genetic material disassembles. However, its mechanism is unknown. Here, we utilize molecular simulations to shed light on the events leading to the capsid disassembly with atomistic detail.
Genetic models of latent tuberculosis in mice reveal differential control by adaptive immunity
Authors: Su Hongwei , Lin Kan , Tiwari Divya , Healy Claire , Trujillo Carolina , Liu Yao , Ioerger Thomas R. , Schnappinger Dirk , Ehrt Sabine
Published: February 2021

Studying latentMycobacterium tuberculosis(Mtb) infection has been limited by the lack of a suitable mouse model. We discovered that transient depletion of protein biotin ligase (BPL) and thioredoxin reductase (TrxB2) results in latent infections during which Mtb cannot be detected but that relapse in a subset of mice. The immune requirements for Mtb control during latency, and the frequency of relapse, were strikingly different depending on how latency was established. TrxB2 depletion resulted in a latent infection that required adaptive immunity for control and reactivated with high frequency, whereas latent infection after BPL depletion was independent of adaptive immunity and rarely reactivated. We identified immune signatures of T cells indicative of relapse and demonstrated that BCG vaccination failed to protect mice from TB relapse. These reproducible genetic latency models allow investigating the host immunological determinants that control the latent state and offer opportunities to evaluate therapeutic strategies in settings that mimic aspects of latency and TB relapse in humans.
Structure and inhibitor binding characterization of oncogenic MLLT1 mutants
Authors: Ni Xiaomin , Londregan Allyn T. , Owen Dafydd R. , Knapp Stefan , Chaikuad Apirat
Published: February 2021

Dysfunction of YEATS-domain-containing MLLT1, an acetyl/acyl-lysine dependent epigenetic reader domain, has been implicated in the development of aggressive cancers. Mutations in the YEATS domain have been recently reported as a cause of MLLT1 aberrant reader function. However, structural basis for the reported alterations in affinity for acetyled/acylated histone has remained elusive. Here, we report the crystal structures of both insertion and substitution present in cancer, revealing significant conformational changes of the YEATS-domain loop 8. Structural comparison demonstrates that such alteration not only altered the binding interface for acetylated/acylated histones, but the sequence alterations in the T1 loop may enable dimeric assembly consistent inducing self-association behavior. Nevertheless, we show that also the MLLT1 mutants can be targeted by developed acetyllysine mimetic inhibitors with affinities similarly to wild type. Our report provides a structural basis for the altered behaviors and potential strategy for targeting oncogenic MLLT1 mutants.
Tacc3 modulates microtubule network dynamicity and focal adhesion remodeling to affect cranial neural crest cell migration inXenopus laevis
Authors: Bearce Elizabeth A. , Pratt Benjamin , Rutherford Erin , Carandang Leslie , Lowery Laura Anne
Published: February 2021

Coordinated cell migration is critical during embryogenesis, as cells must leave their point of origin, navigate a complex barrage of signals, and accurately position themselves to facilitate correct tissue and organ formation. The cell motility process relies on dynamic interactions of the F-actin and microtubule (MT) cytoskeletons. Our work focuses on how one MT plus-end regulator, Transforming Acidic Coiled-Coil 3 (Tacc3), can impact migration of cranial neural crest cells inXenopus laevis. We previously demonstrated thattacc3expression is expressed in cranial neural crest cells, and that Tacc3 can function as a MT plus-end tracking protein to regulate MT growth velocities. Here, we demonstrate that manipulation of Tacc3 protein levels is sufficient to alter cranial neural crest cell velocityin vitro. Tacc3 overexpression drives increased single-cell migration velocities, while Tacc3 KD results in reduced cell velocity and defective explant dispersion. We also show that Tacc3 can have spatially-enhanced effects on MT plus-end growth velocities as well as effects on focal adhesion remodeling. Together, we demonstrate that Tacc3 can facilitate neural crest cell motility through spatially-enhanced cytoskeletal remodeling, which may underlie the enhanced metastatic potential of Tacc3-overexpressing tumor cells.
Pumilio protects Xbp1 mRNA from regulated Ire1-dependent decay
Authors: Cairrao Fatima , Santos Cristiana C , Le Thomas Adrien , Marsters Scot , Ashkenazi Avi , Domingos Pedro M.
Published: February 2021

The unfolded protein response (UPR) maintains homeostasis of the endoplasmic reticulum(ER). Residing in the ER membrane, the UPR mediator Ire1 deploys its cytoplasmic kinase-endoribonuclease domain to activate the key UPR transcription factor Xbp1 through non-conventional splicing of Xbp1 mRNA. Ire1 also degrades diverse ER-targeted mRNAs through regulated Ire1-dependent decay (RIDD), but how it spares Xbp1 mRNA from this decay is unknown. We identified binding sites for the RNA-binding protein Pumilio in the 3’UTRDrosophilaXbp1. In the developingDrosophila eye, Pumilio bound both the Xbp1unsplicedand Xbp1splicedmRNAs, but only Xbp1splicedwas stabilized by Pumilio. Furthermore, Pumilio displayed Ire1 kinase-dependent phosphorylation during ER stress, which was required for its stabilization of Xbp1spliced. Human IRE1 could directly phosphorylate Pumilio, and phosphorylated Pumilio protected Xbp1splicedmRNA against RIDD. Thus, Ire1-mediated phosphorylation enables Pumilio to shield Xbp1splicedfrom RIDD. These results uncover an important and unexpected regulatory link between an RNA-binding protein and the UPR.
Altered TGFB1 regulated pathways promote accelerated tendon healing in the superhealer MRL/MpJ mouse
Authors: Kallenbach Jacob G. , Freeberg Margaret A. T. , Abplanalp David , Myers Jacquelyn A. , Ashton John M. , Loiselle Alayna , Buckley Mark R. , van Wijnen Andre J. , Awad Hani A.
Published: February 2021

To better understand the molecular mechanisms of tendon healing, we investigated the Murphy Roth’s Large (MRL) mouse, which is considered a model of mammalian tissue regeneration. We show that compared to C57Bl/6J (C57) mice, injured MRL tendons have reduced fibrotic adhesions and cellular proliferation, with accelerated improvements in biomechanical properties. Transcriptional analysis of biological drivers showed positive enrichment of TGFB1 in both C57 and MRL healing tendons. However, only MRL tendons exhibited downstream transcriptional effects of cell cycle regulatory genes, with negative enrichment of the cell senescence-related regulators, compared to the positively-enriched inflammatory and ECM organization pathways in the C57 tendons. Serum cytokine analysis revealed decreased levels of circulating senescence-associated circulatory proteins (SASP) in response to injury in the MRL mice compared to the C57 mice. These data collectively demonstrate altered TGFB1 regulated inflammatory, fibrosis, and cell cycle pathways in flexor tendon repair.
Structure of the human SAGA coactivator complex: The divergent architecture of human SAGA allows modular coordination of transcription activation and co-transcriptional splicing
Authors: Herbst Dominik A. , Esbin Meagan N. , Louder Robert K. , Dugast-Darzacq Claire , Dailey Gina M. , Fang Qianglin , Darzacq Xavier , Tjian Robert , Nogales Eva
Published: February 2021

Human SAGA is an essential co-activator complex that regulates gene expression by interacting with enhancer-bound activators, recruiting transcriptional machinery, and modifying chromatin near promoters. Subunit variations and the metazoan-specific requirement of SAGA in development hinted at unique structural features of the human complex. Our 2.9 Å structure of human SAGA reveals intertwined functional modules flexibly connected to a core that distinctively integrates mammalian paralogs, incorporates U2 splicing subunits, and features a unique interface between the core and the activator-binding TRRAP. Our structure sheds light on unique roles and regulation of human coactivators with implications for transcription and splicing that have relevance in genetic diseases and cancer.
Investigating receptor-mediated antibody transcytosis using Blood-Brain Barrier organoid arrays
Authors: Simonneau Claire , Duschmalé Martina , Gavrilov Alina , Brandenberg Nathalie , Hoehnel Sylke , Ceroni Camilla , Lassalle Evodie , Knoetgen Hendrik , Niewoehner Jens , Villaseñor Roberto
Published: February 2021

Background

The pathways that control protein transport across the Blood-Brain Barrier (BBB) remain poorly characterized. Despite great advances in recapitulating the human BBBin vitro, current models are not suitable for systematic analysis of the molecular mechanisms of antibody transport. The gaps in our mechanistic understanding of antibody transcytosis hinder new therapeutic delivery strategy development.

Methods

We applied a novel bioengineering approach to generate human BBB organoids by the self-assembly of astrocytes, pericytes and brain endothelial cells with unprecedented throughput and reproducibility using micro patterned hydrogels. We designed a semi-automated and scalable imaging assay to measure receptor-mediated transcytosis of antibodies. Finally, we developed a workflow to use CRISPR/Cas9 gene editing in BBB organoid arrays to knock out regulators of endocytosis specifically in brain endothelial cells in order to dissect the molecular mechanisms of receptor-mediated transcytosis.

Results

BBB organoid arrays allowed the simultaneous growth of more than 5000 homogenous organoids per individual experiment in a highly reproducible manner. BBB organoid arrays showed low permeability to macromolecules and prevented transport of human non-targeting antibodies. In contrast, a monovalent antibody targeting the human transferrin receptor underwent dose- and time-dependent transcytosis in organoids. Using CRISPR/Cas9 gene editing in BBB organoid arrays, we showed that clathrin, but not caveolin, is required for transferrin receptor-dependent transcytosis.

Conclusions

Human BBB organoid arrays are a robust high-throughput platform that can be used to discover new mechanisms of receptor-mediated antibody transcytosis. The implementation of this platform during early stages of drug discovery can accelerate the development of new brain delivery technologies.
Unfalsified control design using a generalized cost function for a quadrotor
Authors: Hokmabadi Azam , Khodabandeh Mahdi
Published: February 2021

Purpose

The purpose of this paper is to design a controller for a quadrotor only by using input–output data without a need for the system model.

Design/methodology/approach

Tracking control for the quadrotor is considered by using unfalsified control, which is one of the most recent strategies of robust adaptive control. The main assumption in unfalsified control design is that there is no access to the system model. Also, ideal path tracking and controlling the quadrotor are been paid attention to in the presence of external disturbances and uncertainties. First, unfalsified control method is introduced which is a data-driven and model-free approach in the field of adaptive control. Next, model of the quadrotor and unfalsified control design for the quadrotor are presented. Second, design of a control bank consisting of four proportional integral derivative controllers and a sliding mode controller is carried out.

Findings

A particular innovation on an unfalsified control algorithm in this paper is use of a generalized cost function in the hysteresis switching algorithm to find the best controller.

Originality/value

Finally, the performance and robustness of the designed controllers are investigated by simulation studies in various operating conditions including reference trajectory changes, facing to wind disturbance, uncertainty of the system and changes in payload, which show acceptable performances.
Hydrogen as the futuristic fuel for the aviation and aerospace industry – review
Authors: Gunasekar P. , Manigandan S. , T.R. Praveen Kumar
Published: February 2021

Purpose

The rise in demand and high utilization of fuel causes severe environmental threat for the nations on the globe. Rapid burning potential of hydrogen produces enormous amount of thrust, and it is mainly owing to wide flame range and less onset of ignition.

Design/methodology/approach

The significant contribution of hydrogen as fuel has been explored by several researchers around the globe recently to use in aviation sector owing to its eco-friendly nature. Hydrogen is a safe and clean fuel, and it can be generated from several sources. The effects of addition on hydrogen on gas turbine on combustion characteristics and emission concentration level on atmosphere have been reviewed in this paper.

Findings

Incorporation of hydrogen is effective reducing nitrous oxide emission, high calorific value and flame less combustion. Addition of hydrogen to higher proportions enhances the combustion performance, minimizing the setbacks of conventional fuel and meets the specified standards on emission.

Originality/value

From the literature review, the comparative study on hydrogen with other fuel is explained. This paper concludes that addition of hydrogen in fuel enhances the performance of combustion on gas turbine engine along with significant reduction in emission levels.
Storescape and customer loyalty: employee citizenship behaviour towards customers as a catalyst
Authors: Gorji Mohammadbagher , Siami Sahar , Grimmer Louise , Grimmer Martin
Published: February 2021

Purpose

The purpose of the current paper is to examine the relationship between storescape (retail's physical and social environment factors) and customer loyalty (CL) and how employee citizenship behaviour towards customer (ECB-C) facilitates this relationship.

Design/methodology/approach

This study used a descriptive quantitative, non-experimental research method using a cross-sectional design with a self-administered questionnaire. In total, 415 department store customers in Australia responded to the survey through an online panel provider.

Findings

Results confirmed the significance of all relationships between physical and social storescape factors, customer satisfaction (CS) and loyalty, except the direct effect of physical factors on CL. The findings also highlighted the interaction effect of ECB-C in the relationship between storescape factors, satisfaction and CL, indicating that these effects are stronger at higher levels of ECB-C than lower levels.

Practical implications

The study provides insights for department store retailers, practitioners and marketing managers into the role of ECB-C in forming and shaping CS and loyalty, especially when there is a lack of storescape effect on CS and loyalty.

Originality/value

This study extends the consecutive relationship of the stimulus–organism–response (SOR) model by adding ECB-C as a moderator. The study employed resource exchange (RE) theory to investigate the direct effect of storescape on CL beyond its indirect effect through organism suggested by the SOR model.
The effect of human model image backgrounds on consumer responses: empirical evidence from a Chinese apparel e-retailer
Authors: Wu Ruijuan , Li Yan
Published: February 2021

Purpose

The objective of this study was to examine the effects of human model backgrounds (concrete backgrounds vs. solid backgrounds) on consumer responses (attention and attitude) and to determine the mechanism and boundary conditions behind such effects.

Design/methodology/approach

The research consisted of one eye-tracking experiment and two experimental studies.

Findings

The results showed that consumers notice faster and pay more attention to the central figure against solid backgrounds. However, concrete backgrounds elicit more favorable attitudes toward products, and mental imagery mediates the effects of image backgrounds on consumers' attitudes. The authors also found that the situation moderates the relationship between image background and attitude.

Originality/value

The study also supplements the literature on the effects of image backgrounds on consumer responses and the literature on online presentation using human models. Last, the study combines questionnaires with an eye-tracking experiment to obtain a clearer and more comprehensive understanding of the results.
Determinants of bank stability in a small island economy: a study of Fiji
Authors: Chand Shasnil Avinesh , Kumar Ronald Ravinesh , Stauvermann Peter Josef
Published: February 2021

Purpose

This study aims to examine the determinants of bank stability based on three measures of bank stability while accounting for key bank-specific, macro-finance and structural variables. The aim is to underscore key indicators of stability that can be tracked by analysts, bank managers and regulators, especially in small economies such as Fiji.

Design/methodology/approach

The sample comprises a balanced panel of seven banking and financial institutions over the period 2000-2018. For consistency of data and similar functions in terms of deposit and loans, this paper considers five commercial banks and two credit institutions in Fiji. A fixed-effect method of regression is applied, to control for bank heterogeneity. The dependent variable is bank stability, which is based on three measures – the Z-score, the risk-adjusted return on assets and the risk-adjusted equity to assets ratio.

Findings

It is noted that bank size, funding risk, credit risk and Herfindahl-Hirschman index are positively associated with bank stability. In the extended model, both inflation and economic growth are positively associated with bank stability, although only inflation is statistically significant. Moreover, factors having a negative association with bank stability are the liquidity risk, the net interest margin and the remittances inflow. Additionally, the domestically generated political crises of the years 2000 and 2006 and the global financial crisis of 2007–2008 are negatively associated with bank stability.

Originality/value

This study empirically examines the determinants of bank stability in Fiji’s banking sector. Unlike previous studies, this study considers three measures of stability, with z-score as the dominant measure and as explanatory variables, bank-specific, macro-finance and structural variables. The bank-specific data used in the study were hand-picked from the disclosure statements of banks and macro-finance data were extracted from the World Bank Indicators. The study underscores pertinent factors associated with bank stability in the small island economy of Fiji, which can be of interest to analysts, bankers, regulators and researchers in this domain.
People-centred management for improving construction workers' productivity in Zimbabwe
Authors: Moyo Tirivavi , Crafford Gerrit , Emuze Fidelis
Published: February 2021

Purpose

While operational factors reduce construction workers' productivity in Zimbabwe, the impact of the people-centred management aspects has not been empirically interrogated as a remedy. This article reports on a study that sought to determine significant people-centred management aspects that lead to improved labour productivity and assesses the existence of statistically significant differences due to the demographic variables of respondents. Demographic-specific strategies that enhance construction “workers” productivity were revealed.

Design/methodology/approach

The survey research design using a self-administered questionnaire was deployed to collect the primary data. The design followed a positivist paradigm to evaluate objectively how people-centred management affects construction workers' productivity. The statistical data were descriptively and inferentially analysed.

Findings

People-centred management was determined to be significant in improving construction workers' productivity, with the most significant aspect being the building of employee confidence in related approaches. Designations and educational levels mostly indicated a statistically significant difference in several aspects that included the adoption of a functional reward culture for workers and training on people-centred principles. Training on-site management and construction workers in people-centred management and its application are crucial to improving construction workers' productivity.

Research limitations/implications

Construction companies should drastically improve their concern for people while they sustain a high concern for production within their construction sites. Although several factors affect construction workers' productivity, this study determined that management-related factors and people-centred management were significant towards influencing low productivity in Zimbabwe.

Originality/value

The study determined people-centred management and demographic-specific interventions as being able to improve construction workers' productivity in Zimbabwe.
A new two-element MIMO antenna system for cognitive radio applications
Authors: Srikar D. , Anuradha Sundru
Published: February 2021

Purpose

This study aims to propose a two-element multi-input-multi-output (MIMO) antenna for cognitive radio MIMO applications to avoid the complexities involved in reconfigurable antennas and improve the spectrum utilization efficiency.

Design/methodology/approach

The proposed MIMO antenna system comprises a wideband antenna that operates at 2 GHz–12 GHz for sensing the spectrum and four pairs of antennas for communication, which are single and dual-band antennas. Each pair of antennas meant for communication consists of two similar antennas. Moreover, the antennas meant for communication cover 93% of the bandwidth of the sensing antenna.

Findings

The first pair of antennas accessible at ports P2 and P6 and the second pair of antennas accessible at ports P4 and P8, which are dual-band antennas, operate at 3.05 GHz–3.85 GHz, 5.8 GHz–8 GHz and 2.05 GHz–2.55 GHz, 4.7 GHz–6.1 GHz, respectively. While the third pair of antennas accessible at ports P3 and P7 and the fourth pair of antennas accessible at ports P5 and P9 are single-band antennas and operate at 3.85 GHz–4.7 GHz and 8 GHz–11 GHz, respectively. Minimum isolations of 20 dB and 15 dB are attained between every two similar antennas for communication and between the sensing antenna and the antennas meant for communication, respectively. The correctness of the proposed antenna is verified with a fine match between the results obtained from simulations and measurements.

Originality/value

The proposed MIMO antenna possesses salient features, such as polarization diversity and performing a maximum of four communication tasks when all the white spaces are detected.
A novel numerical method for the solution of nonlinear equations with applications to heat transfer
Authors: Reddy J.N. , Martinez Matthew , Nampally Praneeth
Published: February 2021

Purpose

The purpose of this study is to extend a novel numerical method proposed by the first author, known as the dual mesh control domain method (DMCDM), for the solution of linear differential equations to the solution of nonlinear heat transfer and like problems in one and two dimensions.

Design/methodology/approach

In the DMCDM, a mesh of finite elements is used for the approximation of the variables and another mesh of control domains for the satisfaction of the governing equation. Both meshes fully cover the domain but the nodes of the finite element mesh are inside the mesh of control domains. The salient feature of the DMCDM is that the concept of duality (i.e. cause and effect) is used to impose boundary conditions. The method possesses some desirable attributes of the finite element method (FEM) and the finite volume method (FVM).

Findings

Numerical results show that he DMCDM is more accurate than the FVM for the same meshes used. Also, the DMCDM does not require the use of any ad hoc approaches that are routinely used in the FVM.

Originality/value

To the best of the authors’ knowledge, the idea presented in this work is original and novel that exploits the best features of the best competing methods (FEM and FVM). The concept of duality is used to apply gradient and mixed boundary conditions that FVM and its variant do not.
An enhanced cosine-based visual technique for the robust tweets data clustering
Authors: K Narasimhulu , KT Meena Abarna , B Sivakumar
Published: February 2021

Purpose

The purpose of the paper is to study multiple viewpoints which are required to access the more informative similarity features among the tweets documents, which is useful for achieving the robust tweets data clustering results.

Design/methodology/approach

Let “N” be the number of tweets documents for the topics extraction. Unwanted texts, punctuations and other symbols are removed, tokenization and stemming operations are performed in the initial tweets pre-processing step. Bag-of-features are determined for the tweets; later tweets are modelled with the obtained bag-of-features during the process of topics extraction. Approximation of topics features are extracted for every tweet document. These set of topics features of N documents are treated as multi-viewpoints. The key idea of the proposed work is to use multi-viewpoints in the similarity features computation. The following figure illustrates multi-viewpoints based cosine similarity computation of the five tweets documents (here N = 5) and corresponding documents are defined in projected space with five viewpoints, say, v1,v2, v3, v4, and v5. For example, similarity features between two documents (viewpoints v1, and v2) are computed concerning the other three multi-viewpoints (v3, v4, and v5), unlike a single viewpoint in traditional cosine metric.

Findings

Healthcare problems with tweets data. Topic models play a crucial role in the classification of health-related tweets with finding topics (or health clusters) instead of finding term frequency and inverse document frequency (TF–IDF) for unlabelled tweets.

Originality/value

Topic models play a crucial role in the classification of health-related tweets with finding topics (or health clusters) instead of finding TF-IDF for unlabelled tweets.
SiO2 modified graphene oxide hybrids for improving fretting wear performance of ultra-high molecular weight polyethylene
Authors: Xin Xiaocui , Wang Yunxia , Meng Zhaojie , Yan Fengyuan
Published: February 2021

Purpose

The purpose of this paper is to investigate the fretting wear performance of ultra-high-molecular-weight-polyethene (UHMWPE) with addition of GO and SiO2.

Design/methodology/approach

In this study, GO were synthesized and SiO2 nanoparticles were grafted onto GO. The effect of nanofiller on fretting wear performance of UHMWPE was investigated.

Findings

The results indicated that GO was successfully synthesized and SiO2 nanoparticles successfully grafted onto GO. Incorporation of GS was beneficial for the reduction in friction and the improvement in wear resistance of UHMWPE. GO was beneficial for reducing friction coefficient, while SiO2 was good for improving wear resistance. There existed a tribological synergistic effect between GO nanosheet and SiO2 nanoparticles.

Research limitations/implications

The hybrids of GS were promising nanofiller for improving the fretting wear performance of UHMWPE.

Originality/value

The main originality of the research is to reveal the effect of GO and SiO2 nanoparticles on fretting behavior of UHMWPE. The result indicated hybrids of GS were promising nanofiller for improving the fretting wear performance of UHMWPE.
Formulation of control strategy on the environmental impact potential as a result of the development of palm oil plantation
Authors: Syahza Almasdi , Irianti Mitri
Published: February 2021

Purpose

The purpose of this study is to analyze strategies for controlling potential environmental impacts as a result of developing oil palm plantations.

Design/methodology/approach

Research sites in the first year have been carried out in potential areas for the development of oil palm plantations, both through plasma through Badan Usaha Milik Negara (state-owned enterprises) and Badan Usaha Milik Swasta (private-owned companies) and self-help by the community. The research locations were carried out in the Riau mainland areas, including Kampar, Rokan Hulu and Kuantan Singingi regencies. In contrast, the Riau coastal areas were Pelalawan, Siak, Bengkalis, Indragiri Hilir, Indragiri Hulu and Rokan Hilir. The two research areas have different productivity caused by differences in soil fertility. The method used for data collection is the rapid rural appraisal method, which is a participatory approach to obtain data/information and general evaluation in the field in a relatively short time.

Findings

Oil palm commodities are the most popular, especially in the Riau region. This is evidenced by the rapid development of oil palm plantations, namely, 1,119,798 ha in 2001 and increased to 2,372,402 ha in 2013. During the 2001–2013 period, the average growth rate was 6.46% per year, whereas other plantation commodities such as rubber and coconut have decreased. #R2.6 An increase follows the expansion of the plantation area in the production of fresh fruit bunches (FFB). Crude palm oil (CPO) production from 1,792,481 tons in 2001 increased to 7,570,854 tons in 2013, with an average annual growth of 12.76%. CPO production capability in Riau is supported by 172 palm oil mill (POM) units with a processing capacity of 7,800 tons per hour. POM is not spread evenly but is concentrated in nucleus and plasma plantations. Independent smallholders with their scattered land located far from the existing POM. This condition causes the low quality of FFB to the mill due to the distance between the plantation and POM.

Originality/value

The virtue of this research is to find an institutional arrangement strategy for oil palm agriculture to spur growth through the development of the downstream palm oil industry. The strategy is intended to create economic added value so that efforts to accelerate community economic development can be increased.