bluuebunny/crossref_metadata_2025 huggingface dataset:
Impaired Ca2+ Sensitivity of a Novel GCAP1 Variant Causes Cone Dystrophy and Leads to Abnormal Synaptic Transmission Between Photoreceptors and Bipolar Cells
Authors: Marino Valerio , Dal Cortivo Giuditta , Maltese Paolo Enrico , Placidi Giorgio , De Siena Elisa , Falsini Benedetto , Bertelli Matteo , Dell’Orco Daniele
Published: April 2021

Guanylate cyclase-activating protein 1 (GCAP1) is involved in the shutdown of the phototransduction cascade by regulating the enzymatic activity of retinal guanylate cyclase via a Ca2+/cGMP negative feedback. While the phototransduction-associated role of GCAP1 in the photoreceptor outer segment is widely established, its implication in synaptic transmission to downstream neurons remains to be clarified. Here, we present clinical and biochemical data on a novel isolate GCAP1 variant leading to a double amino acid substitution (p.N104K and p.G105R) and associated with cone dystrophy (COD) with an unusual phenotype. Severe alterations of the electroretinogram were observed under both scotopic and photopic conditions, with a negative pattern and abnormally attenuated b-wave component. The biochemical and biophysical analysis of the heterologously expressed N104K-G105R variant corroborated by molecular dynamics simulations highlighted a severely compromised Ca2+-sensitivity, accompanied by minor structural and stability alterations. Such differences reflected on the dysregulation of both guanylate cyclase isoforms (RetGC1 and RetGC2), resulting in the constitutive activation of both enzymes at physiological levels of Ca2+. As observed with other GCAP1-associated COD, perturbation of the homeostasis of Ca2+ and cGMP may lead to the toxic accumulation of second messengers, ultimately triggering cell death. However, the abnormal electroretinogram recorded in this patient also suggested that the dysregulation of the GCAP1–cyclase complex further propagates to the synaptic terminal, thereby altering the ON-pathway related to the b-wave generation. In conclusion, the pathological phenotype may rise from a combination of second messengers’ accumulation and dysfunctional synaptic communication with bipolar cells, whose molecular mechanisms remain to be clarified.
Glass and Jamming Rheology in Soft Particles Made of PNIPAM and Polyacrylic Acid
Authors: Franco Silvia , Buratti Elena , Nigro Valentina , Zaccarelli Emanuela , Ruzicka Barbara , Angelini Roberta
Published: April 2021

The phase behaviour of soft colloids has attracted great attention due to the large variety of new phenomenologies emerging from their ability to pack at very high volume fractions. Here we report rheological measurements on interpenetrated polymer network microgels composed of poly(N-isopropylacrylamide) (PNIPAM) and polyacrylic acid (PAAc) at fixed PAAc content as a function of weight concentration. We found three different rheological regimes characteristic of three different states: a Newtonian shear-thinning fluid, an attractive glass characterized by a yield stress, and a jamming state. We discuss the possible molecular mechanisms driving the formation of these states.
Synthesis of a Coumarin-Based PPARγ Fluorescence Probe for Competitive Binding Assay
Authors: Yoshikawa Chisato , Ishida Hiroaki , Ohashi Nami , Itoh Toshimasa
Published: April 2021

Peroxisome proliferator-activated receptor γ (PPARγ) is a molecular target of metabolic syndrome and inflammatory disease. PPARγ is an important nuclear receptor and numerous PPARγ ligands were developed to date; thus, efficient assay methods are important. Here, we investigated the incorporation of 7-diethylamino coumarin into the PPARγ agonist rosiglitazone and used the compound in a binding assay for PPARγ. PPARγ-ligand-incorporated 7-methoxycoumarin, 1, showed weak fluorescence intensity in a previous report. We synthesized PPARγ-ligand-incorporating coumarin, 2, in this report, and it enhanced the fluorescence intensity. The PPARγ ligand 2 maintained the rosiglitazone activity. The obtained partial agonist 6 appeared to act through a novel mechanism. The fluorescence intensity of 2 and 6 increased by binding to the ligand binding domain (LBD) of PPARγ and the affinity of reported PPARγ ligands were evaluated using the probe.
A Low-Sodium Diet Boosts Ang (1–7) Production and NO-cGMP Bioavailability to Reduce Edema and Enhance Survival in Experimental Heart Failure
Authors: Tripathi Ranjana , Sullivan Ryan D. , Fan Tai-Hwang M. , Mehta Radhika M. , Gladysheva Inna P. , Reed Guy L.
Published: April 2021

Sodium restriction is often recommended in heart failure (HF) to block symptomatic edema, despite limited evidence for benefit. However, a low-sodium diet (LSD) activates the classical renin-angiotensin-aldosterone system (RAAS), which may adversely affect HF progression and mortality in patients with dilated cardiomyopathy (DCM). We performed a randomized, blinded pre-clinical trial to compare the effects of a normal (human-equivalent) sodium diet and a LSD on HF progression in a normotensive model of DCM in mice that has translational relevance to human HF. The LSD reduced HF progression by suppressing the development of pleural effusions (p < 0.01), blocking pathological increases in systemic extracellular water (p < 0.001) and prolonging median survival (15%, p < 0.01). The LSD activated the classical RAAS by increasing plasma renin activity, angiotensin II and aldosterone levels. However, the LSD also significantly up-elevated the counter-regulatory RAAS by boosting plasma angiotensin converting enzyme 2 (ACE2) and angiotensin (1–7) levels, promoting nitric oxide bioavailability and stimulating 3′-5′-cyclic guanosine monophosphate (cGMP) production. Plasma HF biomarkers associated with poor outcomes, such as B-type natriuretic peptide and neprilysin were decreased by a LSD. Cardiac systolic function, blood pressure and renal function were not affected. Although a LSD activates the classical RAAS system, we conclude that the LSD delayed HF progression and mortality in experimental DCM, in part through protective stimulation of the counter-regulatory RAAS to increase plasma ACE2 and angiotensin (1–7) levels, nitric oxide bioavailability and cGMP production.
Expression and Roles of Individual HIF Prolyl 4-Hydroxylase Isoenzymes in the Regulation of the Hypoxia Response Pathway along the Murine Gastrointestinal Epithelium
Authors: Dengler Franziska , Sova Sofia , Salo Antti M. , Mäki Joni M. , Koivunen Peppi , Myllyharju Johanna
Published: April 2021

The HIF prolyl 4-hydroxylases (HIF-P4H) control hypoxia-inducible factor (HIF), a powerful mechanism regulating cellular adaptation to decreased oxygenation. The gastrointestinal epithelium subsists in “physiological hypoxia” and should therefore have an especially well-designed control over this adaptation. Thus, we assessed the absolute mRNA expression levels of the HIF pathway components, Hif1a, HIF2a, Hif-p4h-1, 2 and 3 and factor inhibiting HIF (Fih1) in murine jejunum, caecum and colon epithelium using droplet digital PCR. We found a higher expression of all these genes towards the distal end of the gastrointestinal tract. We detected mRNA for Hif-p4h-1, 2 and 3 in all parts of the gastrointestinal tract. Hif-p4h-2 had significantly higher expression levels compared to Hif-p4h-1 and 3 in colon and caecum epithelium. To test the roles each HIF-P4H isoform plays in the gut epithelium, we measured the gene expression of classical HIF target genes in Hif-p4h-1−/−, Hif-p4h-2 hypomorph and Hif-p4h-3−/− mice. Only Hif-p4h-2 hypomorphism led to an upregulation of HIF target genes, confirming a predominant role of HIF-P4H-2. However, the abundance of Hif-p4h-1 and 3 expression in the gastrointestinal epithelium implies that these isoforms may have specific functions as well. Thus, the development of selective inhibitors might be useful for diverging therapeutic needs.
Carnosic Acid and Carnosol Activate AMPK, Suppress Expressions of Gluconeogenic and Lipogenic Genes, and Inhibit Proliferation of HepG2 Cells
Authors: Hasei Shun , Yamamotoya Takeshi , Nakatsu Yusuke , Ohata Yukino , Itoga Shota , Nonaka Yuji , Matsunaga Yasuka , Sakoda Hideyuki , Fujishiro Midori , Kushiyama Akifumi , Asano Tomoichiro
Published: April 2021

Carnosic acid (CA), carnosol (CL) and rosmarinic acid (RA), components of the herb rosemary, reportedly exert favorable metabolic actions. This study showed that both CA and CL, but not RA, induce significant phosphorylation of AMP-dependent kinase (AMPK) and its downstream acetyl-CoA carboxylase 1 (ACC1) in HepG2 hepatoma cells. Glucose-6-phosphatase (G6PC) and phosphoenolpyruvate carboxykinase 1 (PCK1), rate-limiting enzymes of hepatic gluconeogenesis, are upregulated by forskolin stimulation, and this upregulation was suppressed when incubated with CA or CL. Similarly, a forskolin-induced increase in CRE transcriptional activity involved in G6PC and PCK1 regulations was also stymied when incubated with CA or CL. In addition, mRNA levels of ACC1, fatty acid synthase (FAS) and sterol regulatory element-binding protein 1c (SREBP-1c) were significantly reduced when incubated with CA or CL. Finally, it was shown that CA and CL suppressed cell proliferation and reduced cell viability, possibly as a result of AMPK activation. These findings raise the possibility that CA and CL exert a protective effect against diabetes and fatty liver disease, as well as subsequent cases of hepatoma.
GhNHX3D, a Vacuolar-Localized Na+/H+ Antiporter, Positively Regulates Salt Response in Upland Cotton
Authors: Feng Junping , Ma Wenyu , Ma Zongbin , Ren Zhongying , Zhou Yang , Zhao Junjie , Li Wei , Liu Wei
Published: April 2021

Vacuolar sodium/proton (Na+/H+) antiporters (NHXs) can stabilize ion contents to improve the salt tolerance of plants. Here, GhNHX3D was cloned and characterized from upland cotton (Gossypium hirsutum). Phylogenetic and sequence analyses showed that GhNHX3D belongs to the vacuolar-type NHXs. The GhNHX3D-enhanced green fluorescent protein (eGFP) fusion protein localized on the vacuolar membrane when transiently expressed in Arabidopsis protoplasts. The quantitative real-time PCR (qRT-PCR) analysis showed that GhNHX3D was induced rapidly in response to salt stress in cotton leaves, and its transcript levels increased with the aggravation of salt stress. The introduction of GhNHX3D into the salt-sensitive yeast mutant ATX3 improved its salt tolerance. Furthermore, silencing of GhNHX3D in cotton plants by virus-induced gene silencing (VIGS) increased the Na+ levels in the leaves, stems, and roots and decreased the K+ content in the roots, leading to greater salt sensitivity. Our results indicate that GhNHX3D is a member of the vacuolar NHX family and can confer salt tolerance by adjusting the steady-state balance of cellular Na+ and K+ ions.
STAT6 Is Critical for the Induction of Regulatory T Cells In Vivo Controlling the Initial Steps of Colitis-Associated Cancer
Authors: Delgado-Ramirez Yael , Ocaña-Soriano Angel , Ledesma-Soto Yadira , Olguín Jonadab E. , Hernandez-Ruiz Joselín , Terrazas Luis I. , Leon-Cabrera Sonia
Published: April 2021

Inflammation is the main driver of the tumor initiation and progression in colitis-associated colorectal cancer (CAC). Recent findings have indicated that the signal transducer and activator of transcription 6 (STAT6) plays a fundamental role in the early stages of CAC, and STAT6 knockout (STAT6−/−) mice are highly resistant to CAC development. Regulatory T (Treg) cells play a major role in coordinating immunomodulation in cancer; however, the role of STAT6 in the induction and function of Treg cells is poorly understood. To clarify the contribution of STAT6 to CAC, STAT6−/− and wild type (WT) mice were subjected to an AOM/DSS regimen, and the frequency of peripheral and local Treg cells was determined during the progression of CAC. When STAT6 was lacking, a remarkable reduction in tumor growth was observed, which was associated with decreased inflammation and an increased number of CD4+CD25+Foxp3+ cells in the colon, circulation, and spleen, including an over-expression of TGF-beta, IL-10, and Foxp3, compared to WT mice, during the early stages of CAC development. Conversely, WT mice showed an inverse frequency of Treg cells compared with STAT6−/− mice, which was followed by intestinal tumor formation. Increased mucosal inflammation, histological damage, and tumorigenesis were restored to levels observed in WT mice when an early inhibition/depletion of Treg cells was performed in STAT6−/− mice. Thus, with STAT6 deficiency, an increased number of Treg cells induce resistance against tumorigenesis, arresting tumor-promoting inflammation. We reported a direct role of STAT6 in the induction and function of Treg cells during CAC development and suggest that STAT6 is a potential target for the modulation of immune response in colitis and CAC.
A Novel Volume-Stable Collagen Matrix Induces Changes in the Behavior of Primary Human Oral Fibroblasts, Periodontal Ligament, and Endothelial Cells
Authors: Asparuhova Maria B. , Stähli Alexandra , Guldener Kevin , Sculean Anton
Published: April 2021

The aim of the present study was to investigate the influence of a novel volume-stable collagen matrix (vCM) on early wound healing events including cellular migration and adhesion, protein adsorption and release, and the dynamics of the hemostatic system. For this purpose, we utilized transwell migration and crystal violet adhesion assays, ELISAs for quantification of adsorbed and released from the matrix growth factors, and qRT-PCR for quantification of gene expression in cells grown on the matrix. Our results demonstrated that primary human oral fibroblasts, periodontal ligament, and endothelial cells exhibited increased migration toward vCM compared to control cells that migrated in the absence of the matrix. Cellular adhesive properties on vCM were significantly increased compared to controls. Growth factors TGF-β1, PDGF-BB, FGF-2, and GDF-5 were adsorbed on vCM with great efficiency and continuously delivered in the medium after an initial burst release within hours. We observed statistically significant upregulation of genes encoding the antifibrinolytic thrombomodulin, plasminogen activator inhibitor type 1, thrombospondin 1, and thromboplastin, as well as strong downregulation of genes encoding the profibrinolytic tissue plasminogen activator, urokinase-type plasminogen activator, its receptor, and the matrix metalloproteinase 14 in cells grown on vCM. As a general trend, the stimulatory effect of the vCM on the expression of antifibrinolytic genes was synergistically enhanced by TGF-β1, PDGF-BB, or FGF-2, whereas the strong inhibitory effect of the vCM on the expression of profibrinolytic genes was reversed by PDGF-BB, FGF-2, or GDF-5. Taken together, our data strongly support the effect of the novel vCM on fibrin clot stabilization and coagulation/fibrinolysis equilibrium, thus facilitating progression to the next stages of the soft tissue healing process.
Molecular Mechanisms Underlying the Beneficial Effects of Exercise on Brain Function and Neurological Disorders
Authors: Nay Kévin , Smiles William J. , Kaiser Jacqueline , McAloon Luke M. , Loh Kim , Galic Sandra , Oakhill Jonathan S. , Gundlach Andrew L. , Scott John W.
Published: April 2021

As life expectancy has increased, particularly in developed countries, due to medical advances and increased prosperity, age-related neurological diseases and mental health disorders have become more prevalent health issues, reducing the well-being and quality of life of sufferers and their families. In recent decades, due to reduced work-related levels of physical activity, and key research insights, prescribing adequate exercise has become an innovative strategy to prevent or delay the onset of these pathologies and has been demonstrated to have therapeutic benefits when used as a sole or combination treatment. Recent evidence suggests that the beneficial effects of exercise on the brain are related to several underlying mechanisms related to muscle–brain, liver–brain and gut–brain crosstalk. Therefore, this review aims to summarize the most relevant current knowledge of the impact of exercise on mood disorders and neurodegenerative diseases, and to highlight the established and potential underlying mechanisms involved in exercise–brain communication and their benefits for physiology and brain function.
Carotid Plaque Assessment Reclassifies Patients with Inflammatory Bowel Disease into Very-High Cardiovascular Risk
Authors: Hernández-Camba Alejandro , Carrillo-Palau Marta , Ramos Laura , Hernández Alvarez-Buylla Noemi , Alonso-Abreu Inmaculada , Hernández-Pérez Anjara , Vela Milagros , Arranz Laura , Hernández-Guerra Manuel , González-Gay Miguel Ángel , Ferraz-Amaro Iván
Published: April 2021

The addition of carotid ultrasound into cardiovascular (CV) risk scores has been found to be effective in identifying patients with chronic inflammatory diseases at high-CV risk. We aimed to determine if its use would facilitate the reclassification of patients with inflammatory bowel disease (IBD) into the very high-CV-risk category and whether this may be related to disease features. In this cross-sectional study encompassing 186 IBD patients and 175 controls, Systematic Coronary Risk Evaluation (SCORE), disease activity measurements, and the presence of carotid plaques by ultrasonography were assessed. Reclassification was compared between patients and controls. A multivariable regression analysis was performed to evaluate if the risk of reclassification could be explained by disease-related features and to assess the influence of traditional CV risk factors on this reclassification. After evaluation of carotid ultrasound, a significantly higher frequency of reclassification was found in patients with IBD compared to controls (35% vs. 24%, p = 0.030). When this analysis was performed only on subjects included in the SCORE low-CV-risk category, 21% IBD patients compared to 11% controls (p = 0.034) were reclassified into the very high-CV-risk category. Disease-related data, including disease activity, were not associated with reclassification after fully multivariable regression analysis. Traditional CV risk factors showed a similar influence over reclassification in patients and controls. However, LDL-cholesterol disclosed a higher effect in controls compared to patients (beta coef. 1.03 (95%CI 1.02–1.04) vs. 1.01 (95%CI 1.00–1.02), interaction p = 0.035) after adjustment for confounders. In conclusion, carotid plaque assessment is useful to identify high-CV risk IBD patients.
Complex Liver Resections for Intrahepatic Cholangiocarcinoma
Authors: Reese Tim , Pagel Gregor , Bause Bettina A. , von Rittberg York , Wagner Kim C. , Oldhafer Karl J.
Published: April 2021

The only curative treatment option for intrahepatic cholangiocarcinoma (iCCA) is liver resection. Due to central tumor localization and vascular invasion, complex liver resections play an important role in curative treatment. However, the long-term outcomes after complex liver resection are not known. Methods: A retrospective cohort study was conducted for all patients undergoing liver surgery for iCCA. Complex liver resections included ante situm resections, associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) and major liver resection with vascular reconstructions. Results: Forty-nine patients (34%) received complex liver resection, 66 patients (46%) received conventional liver resection and 28 patients (20%) were not resectable during exploration. Preoperative characteristics were not different between the groups, except for Union for International Cancer Control (UICC) stages. The postoperative course for complex liver resections was associated with more complications and perioperative mortality. However, long-term survival was not different between complex and conventional resections. Independent risk factors for survival were R0 resections and UICC stage. Four patients underwent ante situm resection without any mortality. Conclusions: Complex liver resections are justified in selected patients and survival is comparable with conventional liver resections. Survival in iCCA is affected by UICC stage or resections margins and not by the complexity of the case.
Management of Implantable Cardioverter-Defibrillators during Pregnancy—A Systematic Review
Authors: Topf Albert , Bacher Nina , Kopp Kristen , Mirna Moritz , Larbig Robert , Brandt Mathias C. , Kraus Johannes , Hoppe Uta C. , Motloch Lukas J. , Lichtenauer Michael
Published: April 2021

Background: With the advent of implantable cardioverter-defibrillator (ICD) technology in recent decades, patients with inherited or congenital cardiomyopathy have a greater chance of survival into adulthood. Women with ICDs in this group are now more likely to reach reproductive age. However, pregnancy represents a challenge for clinicians, as no guidelines for the treatment of pregnant women with an ICD are currently available. Methods: To analyze this issue, we performed a systematic screening of the literature using the keywords: pregnancy with ICD, lead fracture in pregnancy, lead thrombi in pregnancy, ventricular tachycardia in pregnancy, inappropriate shocks in pregnancy, ICD discharge in pregnancy and ICD shock in pregnancy. Of 1101 publications found, 27 publications were eligible for further analysis (four retrospective trials and 23 case reports). Results: According to physiological changes in pregnancy, resulting in an increase in heart rate and cardiac output, a vulnerability for malignant arrhythmias and device-related complications in ICD carriers might be suspected. While the literature is limited on this issue, maternal complications including arrhythmia burden with following ICD therapies, thromboembolic events and lead complications as well as inappropriate shock therapy have been reported. According to the limited available studies, associated risk seems not to be more frequent than in the general population and depends on the underlying cardiac pathology. Furthermore, worsening of heart failure and related cardiovascular disease have been reported with associated risk of preterm delivery. These observations are exaggerated by restricted applications of diagnostics and treatment due to the risk of fetal harm in this population. Conclusions: Due to limited data on management of ICDs during pregnancy, further scientific investigations are required. Consequently, careful risk assessment with individual risk evaluation and close follow ups with interdisciplinary treatment are recommended in pregnant ICD carriers.
Forensic Analysis of Umbilical and Newborn Blood Gas Values for Infants at Risk of Cerebral Palsy
Authors: Ross Michael G.
Published: April 2021

Cerebral palsy litigation cases account for the highest claims involving obstetricians/gynecologists, a specialty that ranks among the highest liability medical professions. Although epidemiologic studies indicate that only a small proportion of cerebral palsy (10–20%) is due to birth asphyxia, negligent obstetrical care is often alleged to be the etiologic factor, resulting in contentious medical-legal conflicts. Defense and plaintiff expert opinions regarding the etiology and timing of injury are often polarized, as there is a lack of established methodology for analysis. The objective results provided by umbilical cord and newborn acid/base and blood gas values and the established association with the incidence of cerebral palsy provide a basis for the forensic assessment of both the mechanism and timing of fetal neurologic injury. Using established physiologic and biochemical principles, a series of case examples demonstrates how an unbiased expert assessment can aid in both conflict resolution and opportunities for clinical education.
Fabrication of Porous Carbon Films and Their Impact on Carbon/Polypropylene Interfacial Bonding
Authors: Peng Yucheng , Burtovyy Ruslan , Bordia Rajendra , Luzinov Igor
Published: April 2021

Porous carbon films were generated by thermal treatment of polymer films made from poly(acrylonitrile-co-methyl acrylate)/polyethylene terephthalate (PAN/PET) blend. The precursor films were fabricated by a dip-coating process using PAN/PET solutions in hexafluoro-2-propanol (HFIP). A two-step process, including stabilization and carbonization, was employed to produce the carbon films. PET functioned as a pore former. Specifically, porous carbon films with thicknesses from 0.38–1.83 μm and pore diameters between 0.1–10 μm were obtained. The higher concentrations of PET in the PAN/PET mixture and the higher withdrawal speed during dip-coating caused the formation of larger pores. The thickness of the carbon films can be regulated using the withdrawal speed used in the dip-coating deposition. We determined that the deposition of the porous carbon film on graphite substrate significantly increases the value of the interfacial shear strength between graphite plates and thermoplastic PP. This study has shown the feasibility of fabrication of 3D porous carbon structure on the surface of carbon materials for increasing the interfacial strength. We expect that this approach can be employed for the fabrication of high-performance carbon fiber-thermoplastic composites.
The Importance of Geotechnical Evaluation and Shoreline Evolution in Coastal Vulnerability Index Calculations
Authors: Boumboulis Vasileios , Apostolopoulos Dionysios , Depountis Nikolaos , Nikolakopoulos Konstantinos
Published: April 2021

The aim of this specific study is to present a new weighted Coastal Vulnerability Index (CVIWF), with an emphasis given to the geotechnical evaluation and shoreline evolution rate measured through high-resolution remote sensing, which seem to be the most interfering variables in CVI calculations. As a pilot area for the application of the new CVIWF, the Gulf of Patras in Western Greece was selected, which is suffering erosion problems due to climate change, the sea level rising and human intervention. The new CVIWF, which was applied in this research, includes the following innovations: (1) the use of geotechnical characterization instead of geological–geomorphological characterization, (2) the use of high-resolution remote sensing data for the detection of shoreline evolution rate and (3) the insertion of a specific weighted geotechnical factor in the CVIWF formula. The results from the application of the unweighted CVI show that percentages of 20.13%, 20.47%, 24.56%, 29.39% and 5.45% of the gulf’s shoreline are under the regime of very low, low, moderate, high and very high vulnerability, respectively. On the other hand, the corresponding results from the application of the weighted CVIWF show a percentage of 14.59%, 25.91%, 20.04, 36.48% and 2.98, respectively.
Hydrodynamic Analysis of a Modular Floating Structure with Tension-Leg Platforms and Wave Energy Converters
Authors: Ren Nianxin , Wu Hongbo , Liu Kun , Zhou Daocheng , Ou Jinping
Published: April 2021

This work presents a modular floating structure, which consists of five inner tension-leg platforms and two outermost wave energy converters (denoted as MTLPW). The hydrodynamic interaction effect and the mechanical coupling effect between the five inner tension-leg platforms (TLP) and the two outermost wave energy converters (WEC) are taken into consideration. The effects of the connection modes and power take-off (PTO) parameters of the WECs on the hydrodynamic performance of the MTLPW system are investigated under both operational and extreme sea conditions. The results indicate that the hydrodynamic responses of the MTLPW system are sensitive to the connection type of the outermost WECs. The extreme responses of the bending moment of connectors depend on the number of continuously fixed modules. By properly utilizing hinge-type connectors to optimize the connection mode for the MTLPW system, the effect of more inner TLP modules on the hydrodynamic responses of the MTLPW system can be limited to be acceptable. Therefore, the MTLPW system can be potentially expanded to a large degree.
Factors Determining the Behavioral Intention of Using Food Delivery Apps during COVID-19 Pandemics
Authors: Muangmee Chaiyawit , Kot Sebastian , Meekaewkunchorn Nusanee , Kassakorn Nuttapon , Khalid Bilal
Published: April 2021

The purpose of this study was to investigate the factors determining the behavioral intention of using food delivery apps (FDAs) during COVID-19 pandemics, under a case study of Bangkok, Thailand. The study was necessitated by the increased use of FDAs during the lockdown; online transactions were considered important in preventing the spread of the virus. The study used quantitative techniques involving structural equation model (SEM) to evaluate the effects of exogenous variables on endogenous variables. Primary data were collected from people who had installed and used FDAs. The findings indicated that performance expectancy, effort expectancy, social influence, timeliness, task technology fit, perceived trust, and perceived safety significantly influence the behavioral intention to use (BIU) to use food delivery apps during the COVID-19 pandemic. To this end, effort should be intensified to study and understand FDAs as it pertains to safety and usage.
Future Scenarios for Land Use in Chile: Identifying Drivers of Change and Impacts over Protected Area System
Authors: Benavidez-Silva César , Jensen Magdalena , Pliscoff Patricio
Published: April 2021

Chile is a country that depends on the extraction and export of its natural resources. This phenomenon has exacerbated different processes of transformation and disturbance of natural and human ecosystems. Land use change has become a key factor for the transformation of ecosystems, causing consequences for biodiversity conservation. In this study, current and future (2030, 2050 and 2080) land use categories were evaluated. Land use projections were analysed together with models of ecosystem distribution in Chile under different climate scenarios, to finally analyse different dynamics of land use change within the protected areas system. In all the scenarios evaluated, land use projections showed an increase in the areas of industrial forest plantations and urban areas and a decrease in natural and agricultural areas could be expected. In relation to ecosystem modeling, vegetational formations located in the center and south of the country could be expected to decrease, while vegetational formations in the north and center of the country could extend their surface area. Inside Chile’s protected area network, anthropic disturbances are currently undergoing expansion, which could have consequences for ecosystems and protected areas located in the central and central–south zones of Chile.
Comparison of Two Methods for Total Inorganic Carbon Estimation in Three Soil Types in Mediterranean Area
Authors: Leogrande Rita , Vitti Carolina , Castellini Mirko , Mastrangelo Marcello , Pedrero Francisco , Vivaldi Gaetano Alessandro , Stellacci Anna Maria
Published: April 2021

The objective of this study was to compare the results of calcimetric and dry combustion methods for quantitative estimation of soil total inorganic carbon (TIC). To this aim, 117 soil samples from three localities in the Mediterranean area (one in Spain and two in Southern Italy), representing a wide range of total inorganic carbon contents (ranging from 1.9 to 54 g 100 g−1), were collected. TIC (expressed as CaCO3) was quantified using the volumetric calcimeter method, as reference, and dry combustion in order to find an accurate and rapid method, suitable for different types of soils. The results revealed a concordance between the two methods compared, as shown by the recovery values close to one, for the whole data set and for data grouped per experimental site. Specifically, the dry combustion method showed slightly greater values of TIC compared to volumetric method, probably due to soil acid pretreatments, in dry combustion, and to an incomplete decomposition of carbonates that would require more time for removal, in a calcimeter method. Linear regression equations between the two methods were not affected by different soil types. Overall, our study demonstrated that the dry combustion was a reliable method and could provide accurate estimates of TIC in soils with different calcium carbonate content.
Flexible Supercapacitors Based on Graphene/Boron Nitride Nanosheets Electrodes and PVA/PEI Gel Electrolytes
Authors: Wang Chan , Hu Kuan , Liu Ying , Zhang Ming-Rong , Wang Zhiwei , Li Zhou
Published: April 2021

All-solid-state supercapacitors have gained increasing attention as wearable energy storage devices, partially due to their flexible, safe, and lightweight natures. However, their electrochemical performances are largely hampered by the low flexibility and durability of current polyvinyl alcohol (PVA) based electrolytes. Herein, a novel polyvinyl alcohol-polyethyleneimine (PVA-PEI) based, conductive and elastic hydrogel was devised as an all-in-one electrolyte platform for wearable supercapacitor (WSC). For proof-of-concept, we assembled all-solid-state supercapacitors based on boron nitride nanosheets (BNNS) intercalated graphene electrodes and PVA-PEI based gel electrolyte. Furthermore, by varying the electrolyte ions, we observed synergistic effects between the hydrogel and the electrode materials when KOH was used as electrolyte ions, as the Graphene/BNNS@PVA-PEI-KOH WSCs exhibited a significantly improved areal capacitance of 0.35 F/cm2 and a smaller ESR of 6.02 ohm/cm2. Moreover, due to the high flexibility and durability of the PVA-PEI hydrogel electrolyte, the developed WSCs behave excellent flexibility and cycling stability under different bending states and after 5000 cycles. Therefore, the conductive, yet elastic, PVA-PEI hydrogel represents an attractive electrolyte platform for WSC, and the Graphene/BNNS@PVA-PEI-KOH WSCs shows broad potentials in powering wearable electronic devices.
A Straightforward Approach to Create Ag/SWCNT Composites
Authors: Rdest Monika , Janas Dawid
Published: April 2021

Flexible and conductive materials have a high application potential across many parts of modern life. In this work, thin free-standing films from single-walled carbon nanotubes (SWCNTs) were doped with Ag to enhance their electrical conductivity. A facile method to integrate these two materials is described herein. As a consequence, the material exhibited a six-fold boost to the electrical conductivity: an increase from 250 ± 11 S/cm to 1721 ± 125 S/cm. Interestingly, the specific conductivity remained at a comparable level upon doping, so the material was deemed promising in exploitation fields whereweight is of the essence. Furthermore, the material showed good bending characteristics, thereby revealing its applicability in flexible electronics.
Identification of the Constitutive Model Parameters by Inverse Optimization Method and Characterization of Hot Deformation Behavior for Ultra-Supercritical Rotor Steel
Authors: Chen Xuewen , Du Yuqing , Du Kexue , Lian Tingting , Liu Bingqi , Li Zhipeng , Zhou Xudong
Published: April 2021

X12 (X12CrMoWVNbN10-1-1) ferritic heat resistant steel is an important material for the production of new-generation ultra-supercritical generator rotors. Hot compression tests of X12 ferritic heat-resistant steel were performed via a Gleeble-1500D testing machine under temperatures of 1050–1250 °C and strain rates of 0.05–5 s−1. In order to provide material model data for finite element simulations and accurately predict the hot deformation behavior, a reverse optimization method was proposed to construct elevated temperature constitutive models of X12 ferritic heat-resistant steel in this paper, according to the Hansel–Spittel constitutive model. To verify the accuracy of the model, the predicted and experimental values of the constitutive model were compared. The results indicated that the model had a high prediction accuracy. Meanwhile, the correlation coefficient between the experimental value and the predicted value of constitutive model was 0.97833. For further verification of the accuracy of the model, it was implemented in finite element FORGE@ software to simulate the compression tests of different samples under different conditions. Comparing actual displacement–load curves with displacement–load curves acquired through finite element simulations, the results indicated that displacement–load curves predicted by the model were very consistent with actual displacement–load curves, which verified the accuracy of the model. Moreover, to research the optimal processing parameters of the material, hot processing maps were drawn according to the dynamic material model. In terms of microstructure evolution, a characteristic area distribution map of the hot processing map was established. Therefore, the optimal hot forming parameters regions were in the range of 1150–1200 °C/0.05–0.62 s−1 for X12 ferritic heat-resistant steel.
Evaluation of Drug-Loading Ability of Poly(Lactic Acid)/Hydroxyapatite Core–Shell Particles
Authors: Suzuki Seiya , Lee Sungho , Miyajima Tatsuya , Kato Katsuya , Sugawara-Narutaki Ayae , Sakurai Makoto , Nagata Fukue
Published: April 2021

Poly(lactic acid)/hydroxyapatite (PLA/HAp) core–shell particles are prepared using the emulsification method. These particles are safe for living organisms because they are composed of biodegradable polymers and biocompatible ceramics. These particles are approximately 50–100 nm in size, and their hydrophobic substance loading can be controlled. Hence, PLA/HAp core–shell particles are expected to be used as drug delivery carriers for hydrophobic drugs. In this work, PLA/HAp core–shell particles with a loading of vitamin K1 were prepared, and their drug-loading ability was evaluated. The particles were 40–80 nm in diameter with a PLA core and a HAp shell. The particle size increased with an increase in the vitamin K1 loading. The drug-loading capacity (LC) value of the particles, an indicator of their drug-loading ability, was approximately 250%, which is higher than the previously reported values. The amount of vitamin K1 released from the particles increased as the pH of the soaking solution decreased because the HAp shell easily dissolved under the acidic conditions. The PLA/HAp particles prepared in this work were found to be promising candidates for drug delivery carriers because of their excellent drug-loading ability and pH sensitivity.
Copper-Induced Strengthening in 0.2 C Bainite Steel
Authors: Dlouhy Jaromir , Podany Pavel , Dzugan Jan
Published: April 2021

Bainitic steels were the focus of this study. These steels have the potential to obtain a good combination of strength, ductility, and edge stretchability, which is a very desirable characteristic in the automotive industry. Cu precipitation potential was investigated during prolonged isothermal bainitization treatment. Precipitation strengthening and ductility were measured using a tensile test, and edge stretchability was measured using a hole expansion test. The microstructure was characterized by high-resolution scanning electron microscopy and an electron backscattered diffraction. Lower bainite was obtained by austenitization treatment and subsequent immersion into a salt bath at 400 °C. Cu precipitation occurred after 120 min of holding in the bath and enhanced the yield stress of the Cu-alloyed steel by 120 MPa as compared with a reference steel without Cu. The strengthening did not affect ductility and decreased the edge stretchability by 10%. Steels with different Mn contents were examined. It was found that the enhancement of Mn content from 1 to 2 wt.% did not boost Cu strengthening ability. This result showed that the presence of Mn did not cause an Mn-Cu precipitation strengthening synergy, observed previously during martensite tempering procedure.
Atmospheric Pressure Plasmas in Material Science
Authors: Ptasińska Sylwia
Published: April 2021

The long-term goal of basic material research is to develop theoretical and experimental methodologies to advance the ability to produce materials with the desired compositions and properties that can be used in various applications [...]
Design and Mechanical Compatibility of Nylon Bionic Cancellous Bone Fabricated by Selective Laser Sintering
Authors: Chen Xuewen , Lian Tingting , Zhang Bo , Du Yuqing , Du Kexue , Xiang Nan , Jung Dong-Won , Wang Guangxin , Osaka Akiyoshi
Published: April 2021

In order to avoid the stress shielding phenomenon in orthopedic bionic bone implantation, it is necessary to consider the design of mechanical compatible implants imitating the host bone. In this study, we developed a novel cancellous bone structure design method aimed at ensuring the mechanical compatibility between the bionic bone and human bone by means of computer-aided design (CAD) and finite element analysis technology (specifically, finite element modeling (FEM)). An orthogonal lattice model with volume porosity between 59% and 96% was developed by means of CAD. The effective equivalent elastic modulus of a honeycomb structure with square holes was studied by FEM simulation. With the purpose of verifying the validity of the cancellous bone structure design method, the honeycomb structure was fabricated by selective laser sintering (SLS) and the actual equivalent elastic modulus of the honeycomb structure was measured with a uniaxial compression test. The experimental results were compared with the FEM values and the predicted values. The results showed that the stiffness values of the designed structures were within the acceptable range of human cancellous bone of 50–500 MPa, which was similar to the stiffness values of human vertebrae L1 and L5. From the point of view of mechanical strength, the established cellular model can effectively match the elastic modulus of human vertebrae cancellous bone. The functional relationship between the volume porosity of the nylon square-pore honeycomb structure ranging from 59% to 96% and the effective elastic modulus was established. The effect of structural changes related to the manufacture of honeycomb structures on the equivalent elastic modulus of honeycomb structures was studied quantitatively by finite element modeling.
Correlation between Defects and Electrical Performances of Ion-Irradiated 4H-SiC p–n Junctions
Authors: Pellegrino Domenico , Calcagno Lucia , Zimbone Massimo , Di Franco Salvatore , Sciuto Antonella
Published: April 2021

In this study, 4H-SiC p–n junctions were irradiated with 700 keV He+ ions in the fluence range 1.0 × 1012 to 1.0 × 1015 ions/cm2. The effects of irradiation were investigated by current–voltage (I–V) and capacitance–voltage (C–V) measurements, while deep-level transient spectroscopy (DLTS) was used to study the traps introduced by irradiation defects. Modifications of the device’s electrical performances were observed after irradiation, and two fluence regimes were identified. In the low fluence range (≤1013 ions/cm2), I–V characteristics evidenced an increase in series resistance, which can be associated with the decrease in the dopant concentration, as also denoted by C–V measurements. In addition, the pre-exponential parameter of junction generation current increased with fluence due to the increase in point defect concentration. The main produced defect states were the Z1/2, RD1/2, and EH6/7 centers, whose concentrations increased with fluence. At high fluence (>1013 ions/cm2), I–V curves showed a strong decrease in the generation current, while DLTS evidenced a rearrangement of defects. The detailed electrical characterization of the p–n junction performed at different temperatures highlights the existence of conduction paths with peculiar electrical properties introduced by high fluence irradiation. The results suggest the formation of localized highly resistive regions (realized by agglomeration of point defects) in parallel with the main junction.
Comparison of Graphitic Carbon Nitrides Synthetized from Melamine and Melamine-Cyanurate Complex: Characterization and Photocatalytic Decomposition of Ofloxacin and Ampicillin
Authors: Praus Petr , Smýkalová Aneta , Foniok Kryštof
Published: April 2021

Graphitic carbon nitride (g-C3N4, hereafter abbreviated as CN) was prepared by the heating of melamine (CN-M) and melamine-cyanurate complex (CN-MCA), respectively, in air at 550 °C for 4 h. The specific surface area (SSA) of CN-M and CN-MCA was 12 m2 g−1 and 225 m2g−1 and the content of oxygen was 0.62 wt.% and 1.88 wt.%, respectively. The band gap energy (Eg) of CN-M was 2.64 eV and Eg of CN-MCA was 2.73 eV. The photocatalytic activity of the CN materials was tested by means of the decomposition of antibiotics ofloxacin and ampicillin under LED irradiation of 420 nm. The activity of CN-MCA was higher due to its high SSA, which was determined based on the physisorption of nitrogen. Ofloxacin was decomposed more efficiently than ampicillin in the presence of both photocatalysts.
Tuning of Structural, Dielectric, and Electronic Properties of Cu Doped Co–Zn Ferrite Nanoparticles for Multilayer Inductor Chip Applications
Authors: Hadi Muhammad , Batoo Khalid Mujasam , Chauhan Ankush , Aldossary Omar M. , Verma Ritesh , Yang Yujie
Published: April 2021

Herein, we report the synthesis of nanoparticles and doping of Cu-doped Co–Zn ferrites using the auto-combustion sol–gel synthesis technique. X-ray diffraction studies confirmed the single-phase structure of the samples with space group Fd3m and crystallite size in the range of 20.57–32.69 nm. Transmission electron microscopy micrographs and selected area electron diffraction patterns confirmed the polycrystalline nature of the ferrite nanoparticles. Energy-dispersive X-ray spectroscopy revealed the elemental composition in the absence of any impurity phases. Fourier-transform infrared studies showed the presence of two prominent peaks at approximately 420 cm−1 and 580 cm−1, showing metal–oxygen stretching and the formation of ferrite composite. X-ray photoelectron spectroscopy was employed to determine the oxidation states of Fe, Co, Zn, and Cu and O vacancies based on which cationic distributions at tetrahedral and octahedral sites are proposed. Dielectric spectroscopy showed that the samples exhibit Maxwell–Wagner interfacial polarization, which decreases as the frequency of the applied field increases. The dielectric loss of the samples was less than 1, confirming that the samples can be used for the fabrication of multilayer inductor chips. The ac conductivity of the samples increased with increasing doping and with frequency, and this has been explained by the hopping model. The hysteresis loops revealed that coercivity decreases slightly with doping, while the highest saturation magnetization of 55.61 emu/g was obtained when x = 0.1. The magnetic anisotropic constant was found to be less than 0.5, which suggests that the samples exhibit uniaxial anisotropy rather than cubic anisotropy. The squareness ratio indicates that the samples are useful in high-frequency applications.