bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonlinear-Observer-Based Design Approach for Adaptive Event-Driven Tracking of Uncertain Underactuated Underwater Vehicles
Authors: Kim Jin Hoe , Yoo Sung Jin
Published: May 2021

A nonlinear-observer-based design methodology is proposed for an adaptive event-driven output-feedback tracking problem with guaranteed performance of uncertain underactuated underwater vehicles (UUVs) in six-degrees-of-freedom (6-DOF). A nonlinear observer using adaptive neural networks is presented to estimate the velocity information in the presence of unknown nonlinearities in the dynamics of 6-DOF UUVs where a state transformation approach using a time-varying scaling factor is introduced. Then, an output-feedback tracker using a nonlinear error function and estimated states is recursively designed to overcome the underactuated problem of the system dynamics and to guarantee preselected control performance in three-dimensional space. It is shown that the tracking error of the nonlinear-observer-based output-feedback control system exponentially converges a small neighbourhood around the zero. Efficiency of the resulting output-feedback strategy is verified through a simulation.
On the Existence and Uniqueness of the ODE Solution and Its Approximation Using the Means Averaging Approach for the Class of Power Electronic Converters
Authors: Meo Santolo , Toscano Luisa
Published: May 2021

Power electronic converters are mathematically represented by a system of ordinary differential equations discontinuous right-hand side that does not verify the conditions of the Cauchy-Lipschitz Theorem. More generally, for the properties that characterize their discontinuous behavior, they represent a particular class of systems on which little has been investigated over the years. The purpose of the paper is to prove the existence of at least one global solution in Filippov’s sense to the Cauchy problem related to the mathematical model of a power converter and also to calculate the error in norm between this solution and the integral of its averaged approximation. The main results are the proof of this theorem and the analytical formulation that provides to calculate the cited error. The demonstration starts by a proof of local existence provided by Filippov himself and already present in the literature for a particular class of systems and this demonstration is generalized to the class of electronic power converters, exploiting the non-chattering property of this class of systems. The obtained results are extremely useful for estimating the accuracy of the averaged model used for analysis or control of the effective system. In the paper, the goodness of the analytical proof is supported by experimental tests carried out on a converter prototype representing the class of power electronics converter.
Current Trends in Random Walks on Random Lattices
Authors: Dshalalow Jewgeni H. , White Ryan T.
Published: May 2021

In a classical random walk model, a walker moves through a deterministic d-dimensional integer lattice in one step at a time, without drifting in any direction. In a more advanced setting, a walker randomly moves over a randomly configured (non equidistant) lattice jumping a random number of steps. In some further variants, there is a limited access walker’s moves. That is, the walker’s movements are not available in real time. Instead, the observations are limited to some random epochs resulting in a delayed information about the real-time position of the walker, its escape time, and location outside a bounded subset of the real space. In this case we target the virtual first passage (or escape) time. Thus, unlike standard random walk problems, rather than crossing the boundary, we deal with the walker’s escape location arbitrarily distant from the boundary. In this paper, we give a short historical background on random walk, discuss various directions in the development of random walk theory, and survey most of our results obtained in the last 25–30 years, including the very recent ones dated 2020–21. Among different applications of such random walks, we discuss stock markets, stochastic networks, games, and queueing.
Semi-Supervised Learning Using Hierarchical Mixture Models: Gene Essentiality Case Study
Authors: Daniels Michael W. , Dvorkin Daniel , Powers Rani K. , Kechris Katerina
Published: May 2021

Integrating gene-level data is useful for predicting the role of genes in biological processes. This problem has typically focused on supervised classification, which requires large training sets of positive and negative examples. However, training data sets that are too small for supervised approaches can still provide valuable information. We describe a hierarchical mixture model that uses limited positively labeled gene training data for semi-supervised learning. We focus on the problem of predicting essential genes, where a gene is required for the survival of an organism under particular conditions. We applied cross-validation and found that the inclusion of positively labeled samples in a semi-supervised learning framework with the hierarchical mixture model improves the detection of essential genes compared to unsupervised, supervised, and other semi-supervised approaches. There was also improved prediction performance when genes are incorrectly assumed to be non-essential. Our comparisons indicate that the incorporation of even small amounts of existing knowledge improves the accuracy of prediction and decreases variability in predictions. Although we focused on gene essentiality, the hierarchical mixture model and semi-supervised framework is standard for problems focused on prediction of genes or other features, with multiple data types characterizing the feature, and a small set of positive labels.
Challenges Related to the Processing of Fines in the Recovery of Platinum Group Minerals (PGMs)
Authors: Corin Kirsten , McFadzean Belinda , Shackleton Natalie , O’Connor Cyril
Published: May 2021

In order to increase the recovery of PGMs by flotation, it is necessary to optimise the liberation of the key minerals in which the platinum group elements (PGEs) are contained which include sulphides, arsenides, tellurides, and ferroalloys among others, while at the same time ensuring the optimal depression of gangue minerals. In order to achieve this, comminution circuits usually consist of two or three stages of milling, in which the first stage is autogeneous, followed by ball milling. Further liberation is achieved in subsequent stages using ultra-fine grinding. Each comminution stage is followed by flotation in the so-called MF2 or MF3 circuits. While this staged process increases overall recoveries, overgrinding may occur, hence creating problems associated with fine particle flotation. This paper presents an overview of the mineralogy of most of the more significant PGM ores processed in South Africa and the various technologies used in comminution circuits. The paper then summarises the methodology used in flotation circuits to optimise recovery of fine particles in terms of the collectors, depressants, and frothers used. The effect of entrainment, slimes coating, changes in rheology caused by the presence of a significant amount of fines and of chromite recovery is addressed.
Possible Antidepressant Effects of Memantine—Systematic Review with a Case Study
Authors: Krzystanek Marek , Surma Stanisław , Pałasz Artur , Romańczyk Monika , Krysta Krzysztof
Published: May 2021

The treatment of bipolar depression is hampered by the inadequate efficacy of antidepressants, moderate effect of mood stabilizers, and the side effects of some second-generation antipsychotics. There is limited evidence to date regarding the antidepressant effects of memantine in bipolar depression. The aim of the article was to provide a short review of preclinical and clinical studies on the antidepressant effect of memantine, and to present the case of a bipolar depression patient successfully treated with memantine. The described patient with bipolar disorder was unsuccessfully treated with two mood stabilizers. The addition of memantine at a dose of 20 mg/d to the treatment with lamotrigine and valproic acid resulted in a reduction in the severity of depression measured on the HDRS-17 scale by 35%, and by 47.1% after 7 weeks. The discussion presents experimental evidence for the antidepressant effect of memantine, as well as data from clinical trials in recurrent and bipolar depression. The presented case is the second report in the medical literature showing the antidepressant effect of memantine as an add-on treatment for bipolar depression. The described case and literature analysis indicate that memantine may be an effective and safe method of augmentation of mood stabilizing therapy in bipolar depression.
Comparison of Different Liquid Chromatography-Based Purification Strategies for Adeno-Associated Virus Vectors
Authors: Rieser Ruth , Koch Johanna , Faccioli Greta , Richter Klaus , Menzen Tim , Biel Martin , Winter Gerhard , Michalakis Stylianos
Published: May 2021

Recombinant adeno-associated virus (rAAV) vectors have evolved as one of the most promising technologies for gene therapy due to their good safety profile, high transduction efficacy, and long-term gene expression in nondividing cells. rAAV-based gene therapy holds great promise for treating genetic disorders like inherited blindness, muscular atrophy, or bleeding disorders. There is a high demand for efficient and scalable production and purification methods for rAAVs. This is particularly true for the downstream purification methods. The current standard methods are based on multiple steps of gradient ultracentrifugation, which allow for the purification and enrichment of full rAAV particles, but the scale up of this method is challenging. Here, we explored fast, scalable, and universal liquid chromatography-based strategies for the purification of rAAVs. In contrast to the hydrophobic interaction chromatography (HIC), where a substantial amount of AAV was lost, the cation exchange chromatography (CEX) was performed robustly for multiple tested serotypes and resulted in a mixture of full and empty rAAVs with a good purity profile. For the used affinity chromatography (AC), a serotype dependence was observed. Anion exchange chromatography (AEX) worked well for the AAV8 serotype and achieved high levels of purification and a baseline separation of full and empty rAAVs. Depending on the AAV serotype, a combination of CEX and AEX or AC and AEX is recommended and holds promise for future translational projects that require highly pure and full particle-enriched rAAVs.
On the Effectiveness of Oxygen Plasma and Alkali Surface Treatments to Modify the Properties of Polylactic Acid Scaffolds
Authors: Donate Ricardo , Alemán-Domínguez María Elena , Monzón Mario
Published: May 2021

Surface modification of 3D-printed PLA structures is a major issue in terms of increasing the biofunctionality and expanding the tissue engineering applications of these parts. In this paper, different exposure times were used for low-pressure oxygen plasma applied to PLA 3D-printed scaffolds. Alkali surface treatments were also evaluated, aiming to compare the modifications introduced on the surface properties by each strategy. Surface-treated samples were characterized through the quantification of carboxyl groups, energy-dispersive X-ray spectroscopy, water contact angle measurements, and differential scanning calorimetry analysis. The change in the surface properties was studied over a two-week period. In addition, an enzymatic degradation analysis was carried out to evaluate the effect of the surface treatments on the degradation profile of the 3D structures. The physicochemical characterization results suggest different mechanism pathways for each type of treatment. Alkali-treated scaffolds showed a higher concentration of carboxyl groups on their surface, which enhanced the enzymatic degradation rate, but were also proven to be more aggressive towards 3D-printed structures. In contrast, the application of the plasma treatments led to an increased hydrophilicity of the PLA surface without affecting the bulk properties. However, the changes on the properties were less steady over time.
Creep and Recovery Behavior of Continuous Fiber-Reinforced 3DP Composites
Authors: Al Rashid Ans , Koҫ Muammer
Published: May 2021

The commercial availability of 3D printers for continuous fiber-reinforced 3D-printed (CFR3DP) composites has attracted researchers to evaluate the thermomechanical properties of these materials. The improvement of strength through chopped or continuous fiber reinforcements in polymers could provide remarkable results, and its exploration can provide broad applications in several industries. The evaluation of mechanical properties of these materials at elevated temperatures is vital for their utilization in severe operating conditions. This study provides insight into the effect of different fiber reinforcements (Kevlar, fiberglass, and high-strength high-temperature fiberglass) and temperatures on the creep and recovery behavior of CFR3DP Onyx composites. Experimental results were also compared with analytical models, i.e., Burger’s model and Weibull distribution function, for creep and recovery. Results from analytical models agreed well with experimental results for all the materials and temperatures. A significant drop in maximum and residual strains was observed due to the introduction of fibers. However, the creep resistance of all the materials was affected at higher temperatures. Minimum creep strain was observed for Onyx-FG at 120 °C; however, at the same temperature, the minimum residual strain was observed for Onyx-KF. Based on the analytical models and experimental results, the role of fiber reinforcements on the improvement of creep and recovery performance is also discussed.
Infrared Irradiation Drying Impact on Bee Pollen: Case Study on the Phenolic Composition of Eucalyptus globulus Labill and Salix atrocinerea Brot. Pollens
Authors: Campos Maria G. , Frigerio Christian , Bobiş Otilia , Urcan Adriana C. , Gomes Nelson G. M.
Published: May 2021

Bee pollen is commonly reputed as a rich source of nutrients, both for bees and humans. Its composition is well balanced and can be taken as a stand-alone food or as supplement, including for the elderly owing its low caloric value. However, storage conditions frequently lead to product degradation, namely due to the high moisture content that enable the proliferation of molds and bacteria. Herein, an infrared (IR)-based technology is proposed as a mean to determine moisture content, setting also a new scalable approach for the development of a drying technology to be used for bee pollen processing, which can be carried out in a short time, without impacting the phenolic and flavonoid content and associated bioactive effects. Proof-of-concept was attained with an IR moisture analyzer, bee pollen samples from Eucalyptus globulus Labill and Salix atrocinerea Brot. being selected as models. Impact of the IR radiation towards the phenolic and flavonoid profiles was screened by HPLC/DAD profiling and radical scavenging ability by the DPPH assay. The IR-based approach shows good reproducibility while simultaneously reducing drying time and energy consumption, thus implying a low environmental impact and being suitable for industrial scale-up once no degradation has been found to occur during the radiation process.
Effect of Thermal Energy and Ultrasonication on Mixing Efficiency in Passive Micromixers
Authors: Mahmud Fahizan , Tamrin Khairul Fikri , Mohamaddan Shahrol , Watanabe Nobuo
Published: May 2021

Micromixing is a key process in microfluidics technology. However, rapid and efficient fluid mixing is difficult to achieve inside the microchannels due to unfavourable laminar flow. Active micromixers employing ultrasound and thermal energy are effective in enhancing the micromixing process; however, integration of these energy sources within the devices is a non-trivial task. In this study, ultrasound and thermal energy have been extraneously applied at the upstream of the micromixer to significantly reduce fabrication complexity. A novel Dean micromixer was laser-fabricated to passively increase mixing performance and compared with T- and Y-micromixers at Reynolds numbers between 5 to 100. The micromixers had a relatively higher mixing index at lower Reynolds number, attributed to higher residence time. Dean micromixer exhibits higher mixing performance (about 27% better) than T- and Y-micromixers for 40 ≤ Re ≤ 100. Influence of ultrasound and heat on mixing is more significant at 5 ≤ Re ≤ 20 due to the prolonged mechanical effects. It can be observed that mixing index increases by about 6% to 10% once the temperature of the sonicated fluids increases from 30 °C to 60 °C. The proposed method is potentially useful as direct contact of the inductive energy sources may cause unwanted substrate damage and structural deformation especially for applications in biological analysis and chemical synthesis.
The Relationship between Gratitude, Wellbeing, Spirituality, and Experiencing Meaningful Work
Authors: Loi Natasha M. , Ng Di Helen
Published: May 2021

Poor mental wellbeing not only affects an individual and their family, but it also affects the workplace and the society as a whole. Consequently, it is crucial to investigate approaches that can promote a positive mindset in order to enhance wellbeing. This study aimed to explore the association between gratitude, wellbeing, spirituality, and experiencing meaningful work. A sample of 197 participants (69.5% female) completed measures of gratitude, experiencing meaningful work, spirituality, and several wellbeing indices. Gratitude was significantly positively associated with happiness, life satisfaction, flourishing, positive affect, spirituality, and experiencing meaningful work. A mediation analysis revealed that the relationship between wellbeing and experiencing meaningful work was partially mediated by gratitude. Additionally, spirituality did not moderate the relationship between gratitude and experiencing meaningful work. Overall, the findings indicate that fostering a grateful mindset could enhance wellbeing and work engagement, which in turn could lead to the experience of meaningful work.
SARS-CoV-2, Endothelial Dysfunction, and the Renin-Angiotensin System (RAS): A Potentially Dangerous Triad for the Development of Pre-Eclampsia
Authors: Illi Barbara , Vasapollo Barbara , Valensise Herbert , Totta Pierangela
Published: May 2021

SARS-CoV-2 represents the greatest epidemiological, clinical, and social challenge the human being has had to face in this century. SARS-CoV-2 is not merely a respiratory virus, as its target cells range from upper airway respiratory cells to pulmonary cells but also and above all to the cardiovascular cells, such as pericytes and endothelial cells. Indeed, the pathology related to SARS-CoV-2, COVID-19, may be defined as a thromboinflammatory syndrome in its most severe form, characterized by sepsis-induced coagulopathy (SIC) and disseminated intravascular coagulopathy (DIC), which is prevalent in individuals already presenting a chronic level of inflammation (e.g., obese individuals, elderly) and hypertension. Pregnancy is not only an inflammatory-prone condition but is characterized by a consistent rearrangement of the blood circulation and coagulation profile. Cardiac output increases while arterial systolic and diastolic pressure decrease, regardless of the activation of the RAS system. ACE2, the SARS-CoV-2 entry receptor into the host cells, which transforms Ang II in Ang 1–7, is highly expressed in endothelial, smooth muscle cells and pericytes of placental villi, regulating blood pressure and fetal development. Pre-eclampsia is a pregnancy disorder characterized by hypertension and low levels of ACE2, endothelial dysfunction, and a high production of pro-inflammatory cytokines, resembling COVID-19 manifestations. Whereas pre-eclampsia and COVID-19 have overlapping clinical features, a role for SARS-CoV-2 as a leading cause of pre-eclampsia in COVID-19 positive pregnant women has not been clarified yet. In this mini-review, we will explore the possibility of the existence of such a link, focusing on the role of endothelial dysfunction and RAS in both pre-eclampsia and SARS-CoV-2-induced COVID-19 pathogenesis.
Clofazimine as a Treatment for Multidrug-Resistant Tuberculosis: A Review
Authors: Nugraha Rhea Veda , Yunivita Vycke , Santoso Prayudi , Aarnoutse Rob E. , Ruslami Rovina
Published: May 2021

Multidrug-resistant tuberculosis (MDR-TB) is an infectious disease caused by Mycobacterium tuberculosis which is resistant to at least isoniazid and rifampicin. This disease is a worldwide threat and complicates the control of tuberculosis (TB). Long treatment duration, a combination of several drugs, and the adverse effects of these drugs are the factors that play a role in the poor outcomes of MDR-TB patients. There have been many studies with repurposed drugs to improve MDR-TB outcomes, including clofazimine. Clofazimine recently moved from group 5 to group B of drugs that are used to treat MDR-TB. This drug belongs to the riminophenazine class, which has lipophilic characteristics and was previously discovered to treat TB and approved for leprosy. This review discusses the role of clofazimine as a treatment component in patients with MDR-TB, and the drug’s properties. In addition, we discuss the efficacy, safety, and tolerability of clofazimine for treating MDR-TB. This study concludes that the clofazimine-containing regimen has better efficacy compared with the standard one and is also well-tolerated. Clofazimine has the potential to shorten the duration of MDR-TB treatment.
An Internet of Thing Architecture Based on Message Queuing Telemetry Transport Protocol and Node-RED: A Case Study for Monitoring Radon Gas
Authors: Medina-Pérez Alexandra , Sánchez-Rodríguez David , Alonso-González Itziar
Published: May 2021

This work aims to monitor air quality in places where humans spend most of their time, such as workplaces and homes. Radon gas is a naturally occurring, colourless, odourless and tasteless gas that accumulates in enclosed spaces. It is a radioactive element produced by the decay of its natural parent elements, uranium and thorium, which is harmful to our respiratory system when inhaled. The Internet of Things (IoT) is the key to the problems of contemporary life; we are witnessing an emerging connected world, and these architectures have the potential by using sensors to take data from the physical world, transfer it over the network and store it for further decision making or action. The proposal of this work is based on a radon sensor connected to an IoT device, the Message Queuing Telemetry Transport protocol (MQTT), the Node-RED for managing data flows and a database management system on a web server. The information collected by the sensor is sent by the IoT device to be processed by Node-RED. The obtained data is stored in a database to be represented on a web server. Therefore, this work includes a case study where the technologies involved in the indoor radon gas monitoring system are presented. It is a way to perform radon gas measurements automatically. The final application would allow: displaying radon concentrations on a map with placemarks and updating the information in real-time. The database could record data from other radon sensors that any user wants to associate with this website.
Social Networking Service as a Marketing Technology Tool and Sustainable Business in the Lodging Industry: Investigating the Difference across Older and Younger Age Groups among Tourists
Authors: Han Heesup , Lho Linda-Heejung , Jung Heekyoung , Ariza-Montes Antonio , Araya-Castillo Luis
Published: May 2021

Despite the importance of social networking services (SNSs), their engagement and their role as a critical marketing technology tool in explaining travellers’ approach behaviours are not well known. The present study investigated the influence of SNS engagement on traveller loyalty generation for a chain hotel brand and the health of this business by considering the roles of brand attitude, awareness, trust, and attachment and the impact of age. Fostering customers’ SNS engagement in the hospitality industry will be a vital constituent of hotels’ sustainable business. A quantitative process was used to meet the research objectives. The proposed research framework encompassing these variables was successfully developed. The framework’s efficiency in predicting brand loyalty was also demonstrated. Our results showed that SNS engagement considerably enhances loyalty and other study constructs. Attachment had a salient role in boosting loyalty. In addition, age had a moderating influence. The study constructs maximized the influence of SNS engagement on loyalty as mediators. Overall, our results considerably increase our understanding regarding the role of SNS engagement in the formation of traveller loyalty to chain hotel brands and the sustainability of such businesses.
Use of Mobile Phones in Teaching English in Bangladesh: A Systematic Review (2010–2020)
Authors: Seraj Prodhan Mahbub Ibna , Klimova Blanka , Habil Hadina
Published: May 2021

The use of mobile devices for English language teaching (ELT) is increasing rapidly all over the world. This review study surveys the empirical research on using mobile phones in ELT published in Scopus and Web of Science indexing journals from 2010 to 2020 in Bangladesh. Out of 103 studies, 11 studies met the criteria of this study to analyze the effects of mobile phones on ELT. The findings show that the major research trends of these studies aim at teachers’ professional development using mobile phones for teaching language. The findings also reveal that the use of mobile phones is effective in ELT through facilitating feasible, ubiquitous, and effective learning environments with some limitations, i.e., an issue with charging, a small screen, affection, and a lack of teacher confidence. Of the studies conducted, 83% have employed a qualitative research design for investigating learners’ readiness and concepts on the use of this device. In addition, there is a lack of empirical studies with the intention to observe and justify the effect of mobile phones on developing learners’ language skills. There is also a lack of evidence describing which mobile applications are effective for developing relevant language skills. Overall, the results of this systematic review might be applicable in the context of similarly developing countries, as well as triggering empirical research in the field of technology-enhanced ELT in these countries.
Rapid Differential Detection of Abrin Isoforms by an Acetonitrile- and Ultrasound-Assisted On-Bead Trypsin Digestion Coupled with LC-MS/MS Analysis
Authors: Liang Long-Hui , Yang Yang , Geng Shu , Cheng Xi , Yu Hui-Lan , Liu Chang-Cai , Liu Shi-Lei
Published: May 2021

The high toxic abrin from the plant Abrus precatorius is a type II ribosome-inactivating protein toxin with a human lethal dose of 0.1–1.0 µg/kg body weight. Due to its high toxicity and the potential misuse as a biothreat agent, it is of great importance to developing fast and reliable methods for the identification and quantification of abrin in complex matrices. Here, we report rapid and efficient acetonitrile (ACN)- and ultrasound-assisted on-bead trypsin digestion method combined with HPLC-MS/MS for the quantification of abrin isoforms in complex matrices. Specific peptides of abrin isoforms were generated by direct ACN-assisted trypsin digestion and analyzed by HPLC-HRMS. Combined with in silico digestion and BLASTp database search, fifteen marker peptides were selected for differential detection of abrin isoforms. The abrin in milk and plasma was enriched by immunomagnetic beads prepared by biotinylated anti-abrin polyclonal antibodies conjugated to streptavidin magnetic beads. The ultrasound-assisted on-bead trypsin digestion method was carried out under the condition of 10% ACN as denaturant solvent, the entire digestion time was further shortened from 90 min to 30 min. The four peptides of T3Aa,b,c,d, T12Aa, T15Ab, and T9Ac,d were chosen as quantification for total abrin, abrin-a, abrin-b, and abrin-c/d, respectively. The absolute quantification of abrin and its isoforms was accomplished by isotope dilution with labeled AQUA peptides and analyzed by HPLC-MS/MS (MRM). The developed method was fully validated in milk and plasma matrices with quantification limits in the range of 1.0-9.4 ng/mL for the isoforms of abrin. Furthermore, the developed approach was applied for the characterization of abrin isoforms from various fractions from gel filtration separation of the seeds, and measurement of abrin in the samples of biotoxin exercises organized by the Organization for the Prohibition of Chemical Weapons (OPCW). This study provided a recommended method for the differential identification of abrin isoforms, which are easily applied in international laboratories to improve the capabilities for the analysis of biotoxin samples.
Novel Applications of Non-Invasive Intravesical Botulinum Toxin a Delivery in the Treatment of Functional Bladder Disorders
Authors: Jhang Jia-Fong , Kuo Hann-Chorng
Published: May 2021

Although intravesical botulinum toxin type A (BoNT-A) injection for functional bladder disorders is effective, the injection-related problems—such as bladder pain and urinary tract infection—make the procedure invasive and inconvenient. Several vehicles have recently been developed to deliver BoNT-A without injection, thereby making the treatment less or non-invasive. Laboratory evidence revealed that liposome can carry BoNT-A across the uroepithelium and act on sub-urothelial nerve endings. A randomized placebo controlled study revealed that intravesical administration of liposome-encapsulated BoNT-A and TC-3 hydrogel embedded BoNT-A can improve urinary frequency, urgency, and reduce incontinence in patients with overactive bladders. A single-arm prospective study also revealed that intravesical administration of TC-3 hydrogel embedded BoNT-A can relieve bladder pain in patients with interstitial cystitis/bladder pain syndrome (IC/BPS). We recently administered suprapubic energy shock wave (ESW) after BoNT-A intravesical administration in six patients with IC/BPS. Although pain reduction and symptom improvement were not significant, immunochemical staining showed cleaved synaptosome-associated protein 25 in the bladder after the procedure. This suggests that ESW can promote passage of BoNT-A across the uroepithelium. In conclusion, using vehicles to intra-vesically deliver BoNT-A for functional bladder disorders is promising. Further studies are necessary to confirm the efficacy and explore novel applications.
The Genuine Resonance of Full-Charm Tetraquarks
Authors: Chen Xiaoyun
Published: May 2021

In this work, the genuine resonance states of full-charm tetraquark systems with quantum numbers JPC=0++,1+−,2++ are searched in a nonrelativistic chiral quark model with the help of the Gaussian Expansion Method. In this calculation, two structures, meson-meson and diquark–antidiquark, as well as their mixing with all possible color-spin configurations, are considered. The results show that no bound states can be formed. However, resonances are possible because of the color structure. The genuine resonances are identified by the stabilization method (real scaling method). Several resonances for the full-charm system are proposed, and some of them are reasonable candidates for the full-charm states recently reported by LHCb.
The Casimir Interaction between Spheres Immersed in Electrolytes
Authors: Nunes Renan O. , Spreng Benjamin , de Melo e Souza Reinaldo , Ingold Gert-Ludwig , Maia Neto Paulo A. , Rosa Felipe S. S.
Published: May 2021

We investigate the Casimir interaction between two dielectric spheres immersed in an electrolyte solution. Since ionized solutions typically correspond to a plasma frequency much smaller than kBT/ħ at room temperature, only the contribution of the zeroth Matsubara frequency is affected by ionic screening. We follow the electrostatic fluctuational approach and derive the zero-frequency contribution from the linear Poisson-Boltzmann (Debye-Hückel) equation for the geometry of two spherical surfaces of arbitrary radii. We show that a contribution from monopole fluctuations, which is reminiscent of the Kirkwood-Shumaker interaction, arises from the exclusion of ionic charge in the volume occupied by the spheres. Alongside the contribution from dipole fluctuations, such monopolar term provides the leading-order Casimir energy for very small spheres. Finally, we also investigate the large sphere limit and the conditions for validity of the proximity force (Derjaguin) approximation. Altogether, our results represent the first step towards a full scattering approach to the screening of the Casimir interaction between spheres that takes into account the nonlocal response of the electrolyte solution.
Prediction and Evolution of the Molecular Fitness of SARS-CoV-2 Variants: Introducing SpikePro
Authors: Pucci Fabrizio , Rooman Marianne
Published: May 2021

The understanding of the molecular mechanisms driving the fitness of the SARS-CoV-2 virus and its mutational evolution is still a critical issue. We built a simplified computational model, called SpikePro, to predict the SARS-CoV-2 fitness from the amino acid sequence and structure of the spike protein. It contains three contributions: the inter-human transmissibility of the virus predicted from the stability of the spike protein, the infectivity computed in terms of the affinity of the spike protein for the ACE2 receptor, and the ability of the virus to escape from the human immune response based on the binding affinity of the spike protein for a set of neutralizing antibodies. Our model reproduces well the available experimental, epidemiological and clinical data on the impact of variants on the biophysical characteristics of the virus. For example, it is able to identify circulating viral strains that, by increasing their fitness, recently became dominant at the population level. SpikePro is a useful, freely available instrument which predicts rapidly and with good accuracy the dangerousness of new viral strains. It can be integrated and play a fundamental role in the genomic surveillance programs of the SARS-CoV-2 virus that, despite all the efforts, remain time-consuming and expensive.
Overview of Bat and Wildlife Coronavirus Surveillance in Africa: A Framework for Global Investigations
Authors: Geldenhuys Marike , Mortlock Marinda , Epstein Jonathan H. , Pawęska Janusz T. , Weyer Jacqueline , Markotter Wanda
Published: May 2021

The ongoing coronavirus disease 2019 (COVID-19) pandemic has had devastating health and socio-economic impacts. Human activities, especially at the wildlife interphase, are at the core of forces driving the emergence of new viral agents. Global surveillance activities have identified bats as the natural hosts of diverse coronaviruses, with other domestic and wildlife animal species possibly acting as intermediate or spillover hosts. The African continent is confronted by several factors that challenge prevention and response to novel disease emergences, such as high species diversity, inadequate health systems, and drastic social and ecosystem changes. We reviewed published animal coronavirus surveillance studies conducted in Africa, specifically summarizing surveillance approaches, species numbers tested, and findings. Far more surveillance has been initiated among bat populations than other wildlife and domestic animals, with nearly 26,000 bat individuals tested. Though coronaviruses have been identified from approximately 7% of the total bats tested, surveillance among other animals identified coronaviruses in less than 1%. In addition to a large undescribed diversity, sequences related to four of the seven human coronaviruses have been reported from African bats. The review highlights research gaps and the disparity in surveillance efforts between different animal groups (particularly potential spillover hosts) and concludes with proposed strategies for improved future biosurveillance.
The Immune Correlates of Orthohantavirus Vaccine
Authors: Bae Joon-Yong , Kim Jin Il , Park Mee Sook , Lee Gee Eun , Park Heedo , Song Ki-Joon , Park Man-Seong
Published: May 2021

Zoonotic transmission of orthohantaviruses from rodent reservoirs to humans has been the cause of severe fatalities. Human infections are reported worldwide, but vaccines have been approved only in China and Korea. Orthohantavirus vaccine development has been pursued with no sense of urgency due to the relative paucity of cases in countries outside China and Korea. However, the orthohantaviruses continuously evolve in hosts and thus the current vaccine may not work as well against some variants. Therefore, a more effective vaccine should be prepared against the orthohantaviruses. In this review, we discuss the issues caused by the orthohantavirus vaccine. Given the pros and cons of the orthohantavirus vaccine, we suggest strategies for the development of better vaccines in terms of pandemic preparedness.
Balance between Protection and Pathogenic Response to Aerosol Challenge with Mycobacterium tuberculosis (Mtb) in Mice Vaccinated with TriFu64, a Fusion Consisting of Three Mtb Antigens
Authors: Sulman Sadaf , Savidge Benjamin O. , Alqaseer Kawther , Das Mrinal K. , Nezam Abadi Neda , Pearl John E. , Turapov Obolbek , Mukamolova Galina V. , Akhtar M. Waheed , Cooper Andrea May
Published: May 2021

Tuberculosis vaccines capable of reducing disease worldwide have proven difficult to develop. BCG is effective in limiting childhood disease, but adult TB is still a major public health issue. Development of new vaccines requires identification of antigens that are both spatially and temporally available throughout infection, and immune responses to which reduce bacterial burden without increasing pathologic outcomes. Subunit vaccines containing antigen require adjuvants to drive appropriate long-lived responses. We generated a triple-antigen fusion containing the virulence-associated EsxN (Rv1793), the PPE42 (Rv2608), and the latency associated Rv2628 to investigate the balance between bacterial reduction and weight loss in an animal model of aerosol infection. We found that in both a low pattern recognition receptor (PRR) engaging adjuvant and a high PRR-engaging adjuvant (MPL/TDM/DDA) the triple-antigen fusion could reduce the bacterial burden, but also induced weight loss in the mice upon aerosol infection. The weight loss was associated with an imbalance between TNFα and IL-17 transcription in the lung upon challenge. These data indicate the need to assess both protective and pathogenic responses when investigating subunit vaccine activity.
Prevention of Congenital Cytomegalovirus Infection with Vaccines: State of the Art
Authors: Esposito Susanna , Chiopris Giulia , Messina Giulia , D’Alvano Tiziana , Perrone Serafina , Principi Nicola
Published: May 2021

Cytomegalovirus (CMV) is the most common cause of congenital infection and non-genetic sensorineural hearing loss in childhood. Up to 2% of neonates, with the highest percentages found in developing countries, are congenitally infected with CMV. At birth, most of these infants are asymptomatic. However, approximately 10% have signs and symptoms of the disease, and 40–60% of symptomatic neonates will later develop permanent neurologic sequelae. To reduce congenital CMV (cCMV) infection, a vaccine able to prevent primary infection is essential. In this narrative review, actual ongoing research about the development of a CMV vaccine is discussed. The progressive increase in knowledge on the ways in which the host’s immune system and CMV relate has made it possible to clarify that the development of a vaccine that is certainly capable of reducing the risk of cCMV infection, and preventing both primary and nonprimary infections is extremely difficult. Many of the ways in which the virus evades the immune system and causes cCMV infection are not yet fully understood, especially in cases of nonprimary infection. Moreover, the schedule that should be recommended and that subjects must be vaccinated to obtain the greatest effect have not been precisely defined. Further studies are needed before the problem of cCMV infection and its related challenges can be totally solved.
Influence of Floodplain Flooding on Channel Siltation Adjustment under the Effect of Vegetation on a Meandering Riverine Beach
Authors: Li Junhua , Zhang Mingwu , Jiang Enhui , Pan Li , Wang Aoxue , Wang Yafei , Jian Shengqi
Published: May 2021

Flooding in a sediment-laden floodplain is affected by riverine beach vegetation and the shape of a meandering compound channel. The laws of water and sediment exchange and the deposition distribution in beach troughs are very complex. These factors play a significant role in the formation and development of secondary suspended rivers, in the adjustment of the beach horizontal gradient, and even in the evolution of the flood control situation. In this study, we used a combination of experimental simulation and theoretical research to carry out a generalized model test of floodplain flooding evolution, analyzed the lateral distribution characteristics of sediment-laden flow and sediment factors in a meandering compound channel under the conditions of beach vegetation, and revealed the pros and cons of beach vegetation on the adjustment of the beach and channel siltation. The model test results of the flooding in the floodplain in the compound channel with meandering vegetation showed that the main stream was not only concentrated in the main channel but also appeared near the foot of the left and right bank levees and formed flood discharges along the embankment. As the riverine beach siltation was mainly concentrated at the riverine beach lip, the vegetation on the riverine beach had a significant effect on slowing down the flow velocity. Whether it was a row or full vegetation on both sides of the bank, this played an important role in the stability of the main channel. When there was no vegetation on the riverine beach, the main channel was easy to move. The arrangement of full vegetation on the riverine beach had a uniform effect on the velocity distribution of the riverine beach, which reduced the phenomenon of excessive velocity at the foot of the riverine beach and increased the velocity effect in the main channel. These results will provide a theoretical basis for the utilization of riverine beach areas and river management in the lower Yellow River and have a great significance for enriching the basic theory of water and sediment movement and promoting the integration of hydraulics, river dynamics, and ecology.
Performance of a Handheld Chlorophyll-a Fluorometer: Potential Use for Rapid Algae Monitoring
Authors: Hamdhani Hamdhani , Eppehimer Drew E. , Walker David , Bogan Michael T.
Published: May 2021

Chlorophyll-a measurements are an important factor in the water quality monitoring of surface waters, especially for determining the trophic status and ecosystem management. However, a collection of field samples for extractive analysis in a laboratory may not fully represent the field conditions. Handheld fluorometers that can measure chlorophyll-a in situ are available, but their performance in waters with a variety of potential light-interfering substances has not yet been tested. We tested a handheld fluorometer for sensitivity to ambient light and turbidity and compared these findings with EPA Method 445.0 using water samples obtained from two urban lakes in Tucson, Arizona, USA. Our results suggested that the probe was not sensitive to ambient light and performed well at low chlorophyll-a concentrations (<25 µg/L) across a range of turbidity levels (50–70 NTU). However, the performance was lower when the chlorophyll-a concentrations were >25 µg/L and turbidity levels were <50 NTU. To account for this discrepancy, we developed a calibration equation to use for this handheld fluorometer when field monitoring for potential harmful algal blooms in water bodies.
Evaluation of Element Mobility in River Sediment Using Different Single Extraction Procedures and Assessment of Probabilistic Ecological Risk
Authors: Sakan Sanja , Frančišković-Bilinski Stanislav , Đorđević Dragana , Popović Aleksandar , Sakan Nenad , Škrivanj Sandra , Bilinski Halka
Published: May 2021

In this manuscript, samples of Kupa River sediments were examined using three different extraction agents. The aim of this study was to evaluate the applicability of single extraction procedures to investigate the bioavailability and mobility of major and trace elements (Al, As, Ba, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, P, Pb, S, Si, Sr, Ti, V, and Zn) from river sediment. Two forms of studied elements were evaluated: mobile, the most toxic element form (extraction with 1 M CH3COONH4 and 0.01 M CaCl2) and potentially mobilized form (2 M HNO3 extraction). The estimation of the ecological risk, with the application of the probability distribution of RI (potential ecological risk index) values, is yielded with the help of the Monte Carlo simulation (MCS). Ammonium acetate is proved to be a better extraction agent than calcium chloride. A positive correlation between the content of all extracted elements with nitric acid and the total element content indicates that 2 M HNO3 efficiently extracts all studied elements. Results showed anthropogenic sources of cadmium and copper and high barium mobility. The MCS suggests that risk of Cr, Cu, Ni, Pb, and Zn was low; As and Cd posed a lower and median ecological risk in the studied areas.
Identification of Extreme Weather Events Using Meteorological and Hydrological Indicators in the Laborec River Catchment, Slovakia
Authors: Kubiak-Wójcicka Katarzyna , Nagy Patrik , Zeleňáková Martina , Hlavatá Helena , Abd-Elhamid Hany F.
Published: May 2021

This study used the standardized precipitation index (SPI) and the standardized runoff index (SRI) to analyze dry and humid conditions in the hill-country catchment area of the Laborec River (Slovakia) over a period of 50 years (1970–2019). Analysis of the SPI and SRI over various time scales showed the occurrence of wet periods (index > 1.0) that were associated with precipitation exceeding the long-term norm, and dry periods (index below −1.0), which were the result of small amounts of precipitation. Analysis of the correlation between the SPI and SRI on different time scales revealed that the catchment showed a weaker response to precipitation over short time scales (1 and 3 months) and a stronger response over longer accumulation periods (6, 9, and 12 months). The highest annual correlation coefficient (r = 0.72) was recorded between SRI-6 at the Humenne hydrometric station and SPI-9 at the Medzilaborce meteorological station in the upper part of the catchment area. The strongest annual correlation (r = 0.69) was obtained between the Izkovce and Kamenica stations in the lower part of the catchment area. As shown by the cross-relationships examined over different periods of accumulation of flows and precipitation, hydrological droughts appeared as a result of the occurrence of meteorological droughts with a three-month delay. The conducted analysis showed that in the case of the Laborec river catchment area, there was a strong correlation between the occurrence of meteorological drought and hydrological drought.