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Open AccessReview
The Presence of Toxocara Eggs on Dog’s Fur as Potential Zoonotic Risk in Animal-Assisted Interventions: A Systematic Review
Animals 2019, 9(10), 827; https://doi.org/10.3390/ani9100827 (registering DOI) - 19 Oct 2019
Abstract
Animal-assisted interventions (AAIs) usually contribute to the well-being and health of users/patients, but it is essential that the animals involved in these activities do not represent a source of zoonoses. This systematic review focused on the evaluation of the potential risk of the [...] Read more.
Animal-assisted interventions (AAIs) usually contribute to the well-being and health of users/patients, but it is essential that the animals involved in these activities do not represent a source of zoonoses. This systematic review focused on the evaluation of the potential risk of the transmission of Toxocara by dogs’ fur, considering their involvement as the main animal species in AAIs. Three databases were considered: MEDLINE/PubMed, Scopus, and Web of Science, and the PRISMA guidelines were used. Out of 162 articles found, 14 papers were identified as eligible for inclusion in the review. Although the findings were very heterogeneous, they showed that regular parasitological surveillance to plan effective control programs is strongly needed to guarantee the health of pets and consequently the public health, according to the concept of One Health. Since AAIs involve patients and/or users potentially susceptible, it is very important to appropriately treat dogs enrolled in these interventions after an accurate diagnosis of parasitic zoonoses. Full article
(This article belongs to the Special Issue Human–Animal Relationships and Reservoir Host Status for Zoonoses)
Open AccessFeature PaperArticle
Optimization of Photoperiod and Quality Assessment of Basil Plants Grown in a Small-Scale Indoor Cultivation System for Reduction of Energy Demand
Energies 2019, 12(20), 3980; https://doi.org/10.3390/en12203980 (registering DOI) - 19 Oct 2019
Abstract
Vertical farming is a novel type of food production in indoor environments with artificial lighting and controlled cultivation conditions. In this context, sustainability in small-scale indoor cultivation systems is crucial. Sustainability can be achieved by optimizing all the cultivation factors involved in the [...] Read more.
Vertical farming is a novel type of food production in indoor environments with artificial lighting and controlled cultivation conditions. In this context, sustainability in small-scale indoor cultivation systems is crucial. Sustainability can be achieved by optimizing all the cultivation factors involved in the production process. The effects of different photoperiod conditions under different timing during plant development—from sowing to germination and maturity—have been studied in a small-scale indoor cultivation area. The main objective of this research was to investigate the possibilities of an optimized photoperiod for basil plants to reduce the energy demand cost of the cultivation unit. Three different photoperiod treatments (P8D16L, P10D14L, and P11D13L) were applied to basil plants with stable light intensity. Furthermore, the photoperiod was shortened to test the reaction of the biomass from the plants in a reduced energy demand system. The dry biomass produced was measured along with the energy consumed in each treatment. The basil quality was assessed by measuring different physiological indices, such as chlorophyll a (Chl a), chlorophyll b (Chl b), total chlorophyll (Chl tot), the fraction of photosynthetically active irradiance absorbed by the leaf, and leaf temperature. The results of the study showed that a shorter photoperiod did not negatively affect the quantity and quality of the basil plants. Continuously, the evaluation of the energy demand variation under the different photoperiod treatments can provide a significant positive impact on the energetic, ecological, and economic aspects of small-scale food production. Full article
(This article belongs to the Special Issue Energy Demand and Small Scale Renewable Energy Applications)
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Open AccessArticle
α-Lipoic Acid Inhibits IL-8 Expression by Activating Nrf2 Signaling in Helicobacter pylori-infected Gastric Epithelial Cells
Nutrients 2019, 11(10), 2524; https://doi.org/10.3390/nu11102524 (registering DOI) - 19 Oct 2019
Abstract
Helicobacter pylori (H. pylori) causes gastritis and gastric cancers. Oxidative stress is involved in the pathological mechanism of H. pylori-induced gastritis and gastric cancer induction. Therefore, reducing oxidative stress may be beneficial for preventing the development of H. pylori-associated gastric diseases. [...] Read more.
Helicobacter pylori (H. pylori) causes gastritis and gastric cancers. Oxidative stress is involved in the pathological mechanism of H. pylori-induced gastritis and gastric cancer induction. Therefore, reducing oxidative stress may be beneficial for preventing the development of H. pylori-associated gastric diseases. Nuclear factor erythroid-2-related factor 2 (Nrf2) is a crucial regulator for the expression of antioxidant enzyme heme oxygenase-1 (HO-1), which protects cells from oxidative injury. α-Lipoic acid (α-LA), a naturally occurring dithiol, shows antioxidant and anti-inflammatory effects in various cells. In the present study, we examined the mechanism by which α-LA activates the Nrf2/HO-1 pathway, suppresses the production of pro-inflammatory cytokine interleukine-8 (IL-8), and reduces reactive oxygen species (ROS) in H. pylori-infected AGS cells. α-LA increased the level of phosphorylated and nuclear-translocated Nrf2 by decreasing the amount of Nrf2 sequestered in the cytoplasm by complex formation with Kelch-like ECH1-associated protein 1 (KEAP 1). By using exogenous inhibitors targeting Nrf2 and HO-1, we showed that up-regulation of activated Nrf2 and of HO-1 results in the α-LA-induced suppression of interleukin 8 (IL-8) and ROS. Consumption of α-LA-rich foods may prevent the development of H. pylori-associated gastric diseases by decreasing ROS-mediated IL-8 expression in gastric epithelial cells. Full article
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Open AccessArticle
Semi-Automated Data Analysis for Ion-Selective Electrodes and Arrays Using the R Package ISEtools
Sensors 2019, 19(20), 4544; https://doi.org/10.3390/s19204544 (registering DOI) - 19 Oct 2019
Abstract
A new software package, ISEtools, is introduced for use within the popular open-source programming language R that allows Bayesian statistical data analysis techniques to be implemented in a straightforward manner. Incorporating all collected data simultaneously, this Bayesian approach naturally accommodates sensor arrays [...] Read more.
A new software package, ISEtools, is introduced for use within the popular open-source programming language R that allows Bayesian statistical data analysis techniques to be implemented in a straightforward manner. Incorporating all collected data simultaneously, this Bayesian approach naturally accommodates sensor arrays and provides improved limit of detection estimates, including providing appropriate uncertainty estimates. Utilising >1500 lines of code, ISEtools provides a set of three core functions—loadISEdata, describeISE, and analyseISE— for analysing ion-selective electrode data using the Nikolskii–Eisenman equation. The functions call, fit, and extract results from Bayesian models, automatically determining data structures, applying appropriate models, and returning results in an easily interpretable manner and with publication-ready figures. Importantly, while advanced statistical and computationally intensive methods are employed, the functions are designed to be accessible to non-specialists. Here we describe basic features of the package, demonstrated through a worked environmental application. Full article
(This article belongs to the Special Issue Ion Selective Electrodes and Optodes)
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Open AccessArticle
Pre-, Intra-, and Post-Operative Evaluation of Extraocular Muscle Insertions Using Optical Coherence Tomography: A Comparison of Four Devices
J. Clin. Med. 2019, 8(10), 1732; https://doi.org/10.3390/jcm8101732 (registering DOI) - 19 Oct 2019
Abstract
OCT (optical coherence tomography) is widely used in ophthalmology and pediatric ophthalmology, but limited research has been done on the use of OCT in strabismus. This study investigates the use of different OCT machines to image rectus muscle insertions pre-, intra-, and post-operatively [...] Read more.
OCT (optical coherence tomography) is widely used in ophthalmology and pediatric ophthalmology, but limited research has been done on the use of OCT in strabismus. This study investigates the use of different OCT machines to image rectus muscle insertions pre-, intra-, and post-operatively in pediatric strabismus patients. The OCT machines used in the study were a Bioptigen (Leica Microsystems Inc., Buffalo Grove, IL, USA), Spectralis HRA+OCT with Anterior Segment Module (Heidelberg Engineering, Heidelberg, Germany), Visante (Carl Zeiss, Oberkochen, Germany), and Zeiss Rescan 700 (Carl Zeiss, Oberkochen, Germany). Measurements from the machines were compared with the caliper distance measured during the strabismus surgery before disinsertion or after reattachment. The OCT machines had moderate (Bioptigen: 0.62) to good intraclass correlation coefficients (Rescan: 0.83, Spectralis: 0.85, Visante: 0.88) with intra-operative measurements. To our knowledge, this is the first study to use an operating microscope with integrated intra-operative OCT to image rectus muscle insertions. OCT is a useful tool in strabismus surgical patients in the pre-, intra-, and post-operative settings, particularly in patients who have had previous surgery, when the muscle insertion is unknown. The ability to accurately image rectus muscle insertions has significant implications for the management of strabismus patients. Full article
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Open AccessArticle
Depicting Conformational Ensembles of α-Synuclein by Single Molecule Force Spectroscopy and Native Mass Spectroscopy
Int. J. Mol. Sci. 2019, 20(20), 5181; https://doi.org/10.3390/ijms20205181 (registering DOI) - 19 Oct 2019
Abstract
Description of heterogeneous molecular ensembles, such as intrinsically disordered proteins, represents a challenge in structural biology and an urgent question posed by biochemistry to interpret many physiologically important, regulatory mechanisms. Single-molecule techniques can provide a unique contribution to this field. This work applies [...] Read more.
Description of heterogeneous molecular ensembles, such as intrinsically disordered proteins, represents a challenge in structural biology and an urgent question posed by biochemistry to interpret many physiologically important, regulatory mechanisms. Single-molecule techniques can provide a unique contribution to this field. This work applies single molecule force spectroscopy to probe conformational properties of α-synuclein in solution and its conformational changes induced by ligand binding. The goal is to compare data from such an approach with those obtained by native mass spectrometry. These two orthogonal, biophysical methods are found to deliver a complex picture, in which monomeric α-synuclein in solution spontaneously populates compact and partially compacted states, which are differently stabilized by binding to aggregation inhibitors, such as dopamine and epigallocatechin-3-gallate. Analyses by circular dichroism and Fourier-transform infrared spectroscopy show that these transitions do not involve formation of secondary structure. This comparative analysis provides support to structural interpretation of charge-state distributions obtained by native mass spectrometry and helps, in turn, defining the conformational components detected by single molecule force spectroscopy. Full article
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Open AccessCommunication
The Effect of High Pressure Processing on Polyphenol Oxidase Activity, Phytochemicals and Proximate Composition of Irish Potato Cultivars
Foods 2019, 8(10), 517; https://doi.org/10.3390/foods8100517 (registering DOI) - 19 Oct 2019
Abstract
Polyphenol oxidase (PPO) activity, proximate composition, and phytochemicals were determined in four common Irish potato cultivars following a high pressure processing (HPP) at 600 MPa for 3 min. PPO activity was significantly (p < 0.05) lower in all HPP treated samples, while [...] Read more.
Polyphenol oxidase (PPO) activity, proximate composition, and phytochemicals were determined in four common Irish potato cultivars following a high pressure processing (HPP) at 600 MPa for 3 min. PPO activity was significantly (p < 0.05) lower in all HPP treated samples, while the overall proximate composition was not affected. The total phenolic content was significantly higher in the HPP treated samples. Chlorogenic acid levels significantly decreased with simultaneous increase of caffeic acid and p-coumaric acid levels upon HPP treatment. No significant changes were observed in rutin and ferulic acid levels, although their levels varied, depending on the potato cultivars, while the levels of cytotoxic glycoalkaloids (α-solanine and α-chaconine) remained unaltered. Full article
(This article belongs to the Special Issue Phytochemicals in Food and Health)
Open AccessArticle
Transparent ZnO Thin-Film Deposition by Spray Pyrolysis for High-Performance Metal-Oxide Field-Effect Transistors
Materials 2019, 12(20), 3423; https://doi.org/10.3390/ma12203423 (registering DOI) - 19 Oct 2019
Abstract
Solution-based metal oxide semiconductors (MOSs) have emerged, with their potential for low-cost and low-temperature processability preserving their intrinsic properties of high optical transparency and high carrier mobility. In particular, MOS field-effect transistors (FETs) using the spray pyrolysis technique have drawn huge attention with [...] Read more.
Solution-based metal oxide semiconductors (MOSs) have emerged, with their potential for low-cost and low-temperature processability preserving their intrinsic properties of high optical transparency and high carrier mobility. In particular, MOS field-effect transistors (FETs) using the spray pyrolysis technique have drawn huge attention with the electrical performances compatible with those of vacuum-based FETs. However, further intensive investigations are still desirable, associated with the processing optimization and operational instabilities when compared to other methodologies for depositing thin-film semiconductors. Here, we demonstrate high-performing transparent ZnO FETs using the spray pyrolysis technique, exhibiting a field-effect mobility of ~14.7 cm2 V−1 s−1, an on/off ratio of ~109, and an SS of ~0.49 V/decade. We examine the optical and electrical characteristics of the prepared ZnO films formed by spray pyrolysis via various analysis techniques. The influence of spray process conditions was also studied for realizing high quality ZnO films. Furthermore, we measure and analyze time dependence of the threshold voltage (Vth) shifts and their recovery behaviors under prolonged positive and negative gate bias, which were expected to be attributed to defect creation and charge trapping at or near the interface between channel and insulator, respectively. Full article
(This article belongs to the Special Issue Advanced/Alternative Transparent Conducting Oxides)
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Open AccessArticlePost Publication Peer ReviewVersion 3
On Mautner-Type Probability of Capture of Intergalactic Meteor Particles by Habitable Exoplanets
Sci 2019, 1(3), 61; https://doi.org/10.3390/sci1030061 (registering DOI) - 19 Oct 2019
Abstract
Both macro and microprojectiles (e.g., interplanetary, interstellar and even intergalactic material) are seen as important vehicles for the exchange of potential (bio)material within our solar system as well as between stellar systems in our Galaxy. Accordingly, this requires estimates of the impact probabilities [...] Read more.
Both macro and microprojectiles (e.g., interplanetary, interstellar and even intergalactic material) are seen as important vehicles for the exchange of potential (bio)material within our solar system as well as between stellar systems in our Galaxy. Accordingly, this requires estimates of the impact probabilities for different source populations of projectiles, including for intergalactic meteor particles which have received relatively little attention since considered as rare events (discrete occurrences that are statistically improbable due to their very infrequent appearance). We employ the simple but comprehensive model of intergalactic microprojectile capture by the gravity of exoplanets which enables us to estimate the map of collisional probabilities for an available sample of exoplanets in habitable zones around host stars. The model includes a dynamical description of the capture adopted from Mautner model of interstellar exchange of microparticles and changed for our purposes. We use statistical and information metrics to calculate probability map of intergalactic meteorite particle capture. Moreover, by calculating the entropy index map we estimate the concentration of these rare events. We further adopted a model from immigration theory, to show that the time dependent distribution of single molecule immigration of material indicates high survivability of the immigrated material taking into account birth and death processes on our planet. At present immigration of material can not be observationally constrained but it seems reasonable to think that it will be possible in the near future, and to use it along other proposed parameters for life sustainability on some planet. Full article
(This article belongs to the Special Issue Molecules to Microbes)
Open AccessArticle
Improved Water Services Cooperation through Clarification of Rules and Roles
Water 2019, 11(10), 2172; https://doi.org/10.3390/w11102172 (registering DOI) - 19 Oct 2019
Abstract
Water services face global challenges, many of which are institutional by nature. While technical solutions may suit several situations, institutional frameworks are likely to vary more. On the basis of constructive research approach and new institutional economics we analyze and illustrate water services [...] Read more.
Water services face global challenges, many of which are institutional by nature. While technical solutions may suit several situations, institutional frameworks are likely to vary more. On the basis of constructive research approach and new institutional economics we analyze and illustrate water services and the roles of various water sector actors in Finnish water utility setting using the “soccer analogy” by the Nobel Laureate D.C. North: Institutions are the “formal and informal rules of the game” while organizations are the “players”. Additionally, we assess the Finnish water governance system and discuss issues of scale and fragmentation and distinguish terms water provision and production. Finally, we elaborate the limitations of the soccer analogy to water services through ownership of the systems. According to the soccer analogy, inclusive institutional development requires skillful players (competent staff), team play (collaboration), proper coaching (education), supporters (citizens, media), managers (policymakers), and referees (authorities). We argue that institutional diversity and player/stakeholder collaboration are the foundation for enhancing good multi-level water governance, and that water management, although fragmented, should be seen as a connector of different sectors. For successful outcomes, scientific results should be communicated to public in more common language. Full article
(This article belongs to the Special Issue Selected Papers from 2019 World Water Week)
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Open AccessArticle
Differential Expression of Genes Related to the Formation of Giant Leaves in Triploid Poplar
Forests 2019, 10(10), 920; https://doi.org/10.3390/f10100920 (registering DOI) - 19 Oct 2019
Abstract
Plant polyploids tend to have large leaves, but their formation mechanism has not yet been well explained. Therefore, daily transcriptomic differences between triploids and diploids from a synthetic Populus sect. Tacamahaca three times a day (i.e., 04:00, 09:00, and 21:00) were investigated using [...] Read more.
Plant polyploids tend to have large leaves, but their formation mechanism has not yet been well explained. Therefore, daily transcriptomic differences between triploids and diploids from a synthetic Populus sect. Tacamahaca three times a day (i.e., 04:00, 09:00, and 21:00) were investigated using high-throughput RNA-seq analysis. In this study, we identified several transcription factors associated with giant leaves. The combined effects included the high expression of several transcription factors (WRKY, MYB, etc.) and hormone-related genes (e.g., activates auxin, cytokine, and brassinosteroid synthesis-related genes) that accelerate the synthesis and accumulation of endogenous hormones. High levels of growth hormones were maintained by reducing the genes’ expression of hormone metabolism and degradation. The coordination of hormones accumulated sufficient materials and energy for leaf growth and development. Thereby, cell division and growth were accelerated which enhanced the photosynthesis of leaves, and the increased accumulation of photosynthetic products led to giant triploid leaves. This study lays the foundation for revealing the molecular mechanisms in the formation of giant leaves in polyploids. Full article
(This article belongs to the Special Issue Forest Genetic and Tree Improvement)
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Open AccessArticle
Enhancement of Astaxanthin Biosynthesis in Oleaginous Yeast Yarrowia lipolytica via Microalgal Pathway
Microorganisms 2019, 7(10), 472; https://doi.org/10.3390/microorganisms7100472 (registering DOI) - 19 Oct 2019
Abstract
Astaxanthin is a high-value red pigment and antioxidant used by pharmaceutical, cosmetics, and food industries. The astaxanthin produced chemically is costly and is not approved for human consumption due to the presence of by-products. The astaxanthin production by natural microalgae requires large open [...] Read more.
Astaxanthin is a high-value red pigment and antioxidant used by pharmaceutical, cosmetics, and food industries. The astaxanthin produced chemically is costly and is not approved for human consumption due to the presence of by-products. The astaxanthin production by natural microalgae requires large open areas and specialized equipment, the process takes a long time, and results in low titers. Recombinant microbial cell factories can be engineered to produce astaxanthin by fermentation in standard equipment. In this work, an oleaginous yeast Yarrowia lipolytica was engineered to produce astaxanthin at high titers in submerged fermentation. First, a platform strain was created with an optimised pathway towards β-carotene. The platform strain produced 331 ± 66 mg/L of β-carotene in small-scale cultivation, with the cellular content of 2.25% of dry cell weight. Next, the genes encoding β-ketolase and β-hydroxylase of bacterial (Paracoccus sp. and Pantoea ananatis) and algal (Haematococcus pluvialis) origins were introduced into the platform strain in different copy numbers. The resulting strains were screened for astaxanthin production, and the best strain, containing algal β-ketolase and β-hydroxylase, resulted in astaxanthin titer of 44 ± 1 mg/L. The same strain was cultivated in controlled bioreactors, and a titer of 285 ± 19 mg/L of astaxanthin was obtained after seven days of fermentation on complex medium with glucose. Our study shows the potential of Y. lipolytica as the cell factory for astaxanthin production. Full article
(This article belongs to the Special Issue Non-conventional Yeasts: Genomics and Biotechnology)
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Open AccessArticle
Plasma Levels of Oxidative Stress Markers, before and after BoNT/A Treatment, in Chronic Migraine
Toxins 2019, 11(10), 608; https://doi.org/10.3390/toxins11100608 (registering DOI) - 19 Oct 2019
Abstract
The pathophysiological mechanisms of migraine transformation are debated. Modifications of plasma oxidative stress biomarkers have been described in chronic migraine. OnabotulintoxinA (BoNT/A) treatment, approved for chronic migraine prophylaxis, possibly reduces pain neurotransmitters release and oxidative stress products. Aims of our study were to [...] Read more.
The pathophysiological mechanisms of migraine transformation are debated. Modifications of plasma oxidative stress biomarkers have been described in chronic migraine. OnabotulintoxinA (BoNT/A) treatment, approved for chronic migraine prophylaxis, possibly reduces pain neurotransmitters release and oxidative stress products. Aims of our study were to investigate differences in the levels of selected plasmatic oxidative stress biomarkers (Advanced Oxidation Protein Products (AOPP), Ferric Reducing Antioxidant Power (FRAP), Thiolic Groups (SH)) comparing chronic migraineurs (CM) and healthy controls (HC). We also explored possible clinical and biochemical modifications in the CM group after six months of treatment with BoNT/A. At the baseline, we found higher values of AOPP (p < 0.001), and lower values of SH (p < 0.001) and FRAP (p = 0.005) in the CM group. At the six-month follow-up we found a reduction of AOPP (p < 0.001) and an increase of FRAP (p < 0.001) and SH (p = 0.023) within the CM group. BoNT/A treatment improved migraine symptoms in the CM group. We confirmed previous reports of imbalanced antioxidant mechanisms in chronic migraine showing lower antioxidant capacities in patients than controls. BoNT/A improved the levels of plasma oxidative stress biomarkers and confirmed its role as an effective prophylactic treatment for CM. Other studies should investigate the potential antioxidant properties of BoNT/A treatment. Full article
(This article belongs to the Special Issue Botulinum Toxin for Neuropathic Pain Treatment)
Open AccessArticle
The HER2 S310F Mutant Can Form an Active Heterodimer with the EGFR, Which Can Be Inhibited by Cetuximab but Not by Trastuzumab as well as Pertuzumab
Biomolecules 2019, 9(10), 629; https://doi.org/10.3390/biom9100629 (registering DOI) - 19 Oct 2019
Abstract
G309 or S310 mutations on the HER2 extracellular domain II induce receptor activation. Clinically, S310F is most frequent among HER2 extracellular domain mutations and patients with the S310F mutation without HER2 amplification responded to trastuzumab with or without the pertuzumab combination. However, the [...] Read more.
G309 or S310 mutations on the HER2 extracellular domain II induce receptor activation. Clinically, S310F is most frequent among HER2 extracellular domain mutations and patients with the S310F mutation without HER2 amplification responded to trastuzumab with or without the pertuzumab combination. However, the ability of S310F mutant to form homodimers or heterodimers with wild-type HER2 and other HER receptors, or their reactivity to trastuzumab and pertuzumab treatments, has not been reported. We overexpressed S310F as well as G309A, G309E and S310Y HER2 mutants and tested their reactivity to trastuzumab and pertuzumab. All mutants reacted to trastuzumab, but S310F mutant did not react to pertuzumab along with S310Y or G309E mutants. Thereafter, we tested the effects of trastuzumab and pertuzumab on 5637 cell line expressing both wild-type HER2 and S310F mutant. The ligand-independent HER2 homodimerization blocking antibody, trastuzumab, did not inhibit the activation of the HER2 receptor, suggesting that the S310F HER2 mutant did not form homodimers or heterodimers with wild-type HER2. Because 5637 cells overexpressed the EGFR, the effects of cetuximab and gefitinib were determined, and both inhibited the activation of HER2 and significantly reduced cell growth. Because pertuzumab did not inhibit the phosphorylation of HER2 while it bound to wild-type HER2, EGFR-mediated phosphorylation is expected to occur on the S310F mutant. To confirm whether the S310F mutant HER2 retained its affinity to the EGFR, single molecule interaction analyses using TIRF microscopy were performed, which showed that S310F mutant successfully formed complexes with EGFR. In conclusion, HER2 S310F mutant can form an active heterodimer with the EGFR and it can be inhibited by cetuximab, but not by trastuzumab in combination with pertuzumab. Full article
(This article belongs to the Special Issue Advances in Antibody Therapy of Cancer)
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Open AccessArticle
A Novel Strategy Based on Linear Active Disturbance Rejection Control for Harmonic Detection and Compensation in Low Voltage AC Microgrid
Energies 2019, 12(20), 3982; https://doi.org/10.3390/en12203982 (registering DOI) - 19 Oct 2019
Abstract
In an AC microgrid, harmonic distortion is mainly caused by power electronic equipment and nonlinear loads. In this paper, linear active disturbance rejection control (LADRC) is used to control the fundamental current at the point of common coupling (PCC). Meanwhile, an active power [...] Read more.
In an AC microgrid, harmonic distortion is mainly caused by power electronic equipment and nonlinear loads. In this paper, linear active disturbance rejection control (LADRC) is used to control the fundamental current at the point of common coupling (PCC). Meanwhile, an active power filter (APF) is added to eliminate the harmonic current generated by the nonlinear loads. The tracking differentiator (TD) in active disturbance rejection control (ADRC) serves as a low-pass filter (LPF) in the harmonic detection algorithm of APF. Compared to traditional harmonic detection algorithms, the improved strategy solves the contradiction between rapidity, accuracy, and overshoot of filtering. LADRC has good performance of disturbance rejection, internal decoupling, and accessible parameters tuning. It can observe the internal uncertainty and external disturbance of the system as the total disturbance through the extended state observer (ESO), and compensate it in time through state feedback to make the system achieve the desired performance. The abilities of resonance suppression for LCL-type filter and internal decoupling of LADRC demonstrates its advantages through frequency domain analysis and simulation. The proposed strategy was simulated in MATLAB/SIMULINK and realized in the experimental hardware platform, and the effectiveness of the proposed strategy is approved. Full article
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