bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Placental Abnormalities and Pregnancy-Induced Hypertension in Prematurity Associated with Various Assisted Reproductive Technology Techniques
Authors: Stern Judy E. , Liu Chia-ling , Hwang Sunah S. , Dukhovny Dmitry , Farland Leslie V. , Diop Hafsatou , Coddington Charles C. , Cabral Howard
Published: April 2021

Objective. Assisted reproductive technology (ART)-treated women exhibit increased risk of premature delivery compared to fertile women. We evaluated whether ART treatment modalities increase prematurity and whether placental abnormalities and pregnancy-induced hypertensive (PIH) disorders mediate these risks. Method(s): This retrospective study of ART-treated and fertile deliveries (2004–2017) used an ART-cycle database linked to Massachusetts birth certificates and hospital discharges. Outcomes of late preterm birth (LPTB: 34–36 weeks gestation) and early preterm birth (EPTB: <34 weeks gestation) were compared with term deliveries (≥37 weeks gestation) in ART-treated (linked to the ART database) and fertile (no indicators of infertility or ART) deliveries. ART treatments with autologous oocyte, donor oocyte, fresh or frozen embryo transfer (FET), intracytoplasmic sperm injection (ICSI) and no-ICSI were separately compared to the fertile group. Adjusted odds ratios (AOR) were calculated with multivariable logistic regression: placental abnormalities or PIH were quantified in the pathway as mediators. Results: There were 218,320 deliveries: 204,438 fertile and 13,882 ART-treated. All treatment types increased prematurity (AOR 1.31–1.58, LPTB; AOR 1.34–1.48, EPTB). Placental abnormalities mediated in approximately 22% and 38% of the association with LPTB and EPTB, respectively. PIH mediated 25% and 33% of the association with LPTB and EPTB in FET and donor oocyte cycles, more than other treatments (<10% LPTB and <13% EPTB). Conclusions: ART-treatment and all ART modalities increased LPTB and EPTB when compared with fertile deliveries. Placental abnormalities modestly mediated associations approximately equally, while PIH was a stronger mediator in FET and donor oocyte cycles. Reasons for differences require exploration.
Founder Effects in Hereditary Hemorrhagic Telangiectasia
Authors: Major Tamás , Gindele Réka , Balogh Gábor , Bárdossy Péter , Bereczky Zsuzsanna
Published: April 2021

A founder effect can result from the establishment of a new population by individuals from a larger population or bottleneck events. Certain alleles may be found at much higher frequencies because of genetic drift immediately after the founder event. We provide a systematic literature review of the sporadically reported founder effects in hereditary hemorrhagic telangiectasia (HHT). All publications from the ACVRL1, ENG and SMAD4 Mutation Databases and publications searched for terms “hereditary hemorrhagic telangiectasia” and “founder” in PubMed and Scopus, respectively, were extracted. Following duplicate removal, 141 publications were searched for the terms “founder” and “founding” and the etymon “ancest”. Finally, 67 publications between 1992 and 2020 were reviewed. Founder effects were graded upon shared area of ancestry/residence, shared core haplotypes, genealogy and prevalence. Twenty-six ACVRL1 and 12 ENG variants with a potential founder effect were identified. The bigger the cluster of families with a founder mutation, the more remarkable is its influence to the populational ACVRL1/ENG ratio, affecting HHT phenotype. Being aware of founder effects might simplify the diagnosis of HHT by establishing local genetic algorithms. Families sharing a common core haplotype might serve as a basis to study potential second-hits in the etiology of HHT.
Venetoclax-Based Regimens for Relapsed/Refractory Acute Myeloid Leukemia in a Real-Life Setting: A Retrospective Single-Center Experience
Authors: Piccini Matteo , Pilerci Sofia , Merlini Marta , Grieco Pietro , Scappini Barbara , Bencini Sara , Peruzzi Benedetta , Caporale Roberto , Signori Leonardo , Pancani Fabiana , Vannucchi Alessandro Maria , Gianfaldoni Giacomo
Published: April 2021

Relapsed/refractory (R/R) acute myeloid leukemia (AML) is a largely unmet medical need, owing to the lack of standardized, effective treatment approaches, resulting in an overall dismal outcome. The only curative option for R/R AML patients is allogeneic hematopoietic stem cell transplantation (HSCT) which is only applicable in a fraction of patients due to the scarce efficacy and high toxicity of salvage regimens. Recently, a number of targeted agents with relatively favorable toxicity profiles have been explored in clinical trials for R/R AML patients. The Bcl-2 inhibitor venetoclax, in combination with hypomethylating agents or low dose cytarabine, has produced impressive results for newly diagnosed AML, while its role in R/R disease is not well defined yet. We retrospectively analyzed the clinical outcomes of 47 R/R AML patients treated with venetoclax-based regimens between March 2018 and December 2020 at our institution. Overall, we report a composite complete response rate of 55% with an overall acceptable toxicity profile. Outcomes were particularly favorable for NPM1 mutated patients, unlike for FLT3-ITD positive patients irrespective of NPM1 status. For patients treated with intention to transplant, the procedure could be finally performed in 54%. These findings suggest a role for venetoclax-based regimens in R/R AML patients and support the design of prospective studies.
A Barotropic Solver for High-Resolution Ocean General Circulation Models
Authors: Yang Xiaodan , Zhou Shan , Zhou Shengchang , Song Zhenya , Liu Weiguo
Published: April 2021

High-resolution global ocean general circulation models (OGCMs) play a key role in accurate ocean forecasting. However, the models of the operational forecasting systems are still not in high resolution due to the subsequent high demand for large computation, as well as the low parallel efficiency barrier. Good scalability is an important index of parallel efficiency and is still a challenge for OGCMs. We found that the communication cost in a barotropic solver, namely, the preconditioned conjugate gradient (PCG) method, is the key bottleneck for scalability due to the high frequency of the global reductions. In this work, we developed a new algorithm—a communication-avoiding Krylov subspace method with a PCG (CA-PCG)—to improve scalability and then applied it to the Nucleus for European Modelling of the Ocean (NEMO) as an example. For PCG, inner product operations with global communication were needed in every iteration, while for CA-PCG, inner product operations were only needed every eight iterations. Therefore, the global communication cost decreased from more than 94.5% of the total execution time with PCG to less than 63.4% with CA-PCG. As a result, the execution time of the barotropic modes decreased from more than 17,000 s with PCG to less than 6000 s with CA-PCG, and the total execution time decreased from more than 18,000 s with PCG to less than 6200 s with CA-PCG. Besides, the ratio of the speedup can also be increased from 3.7 to 4.6. In summary, the high process count scalability when using CA-PCG was effectively improved from that using the PCG method, providing a highly effective solution for accurate ocean simulation.
Illusion vs. Disillusion: Chinese Viewers’ Articulation of “House of Cards”
Authors: Liu Zhaoxi (Josie)
Published: April 2021

This study explores how Chinese viewers articulate the meaning of the Netflix series “House of Cards” through analyzing viewer comments posted on Sohu Video, which streamed the show in China. A qualitative textual analysis of the comments reveals that the Sohu viewers turned the commenting of the show into articulations of democracy and China’s political conditions. In their articulation, some endorsed American democracy as a superb political system, while others resented it as being dark and corrupt, similar to the one in China. Still other viewers made a connection between “Cards” with China’s lack of freedom of speech. These connections were made under certain social conditions, including China’s internet providing a space for political discourse, tensions among different social forces and conflicting meaning systems existing in today’s China, and Chinese people’s increasing consumption of foreign media content and assumptions. Analyzing a particular case of transnational communication, this study demonstrates how the audience can make meaning of a foreign media product by connecting with their own social context, and how such articulations can be plural and multifaceted.
Blood-Derived Biomarkers of Diagnosis, Prognosis and Therapy Response in Prostate Cancer Patients
Authors: Balázs Katalin , Antal Lilla , Sáfrány Géza , Lumniczky Katalin
Published: April 2021

Prostate cancer is among the most frequent cancers in men worldwide. Despite the fact that multiple therapeutic alternatives are available for its treatment, it is often discovered in an advanced stage as a metastatic disease. Prostate cancer screening is based on physical examination of prostate size and prostate-specific antigen (PSA) level in the blood as well as biopsy in suspect cases. However, these markers often fail to correctly identify the presence of cancer, or their positivity might lead to overdiagnosis and consequent overtreatment of an otherwise silent non-progressing disease. Moreover, these markers have very limited if any predictive value regarding therapy response or individual risk for therapy-related toxicities. Therefore, novel, optimally liquid biopsy-based (blood-derived) markers or marker panels are needed, which have better prognostic and predictive value than the ones currently used in the everyday routine. In this review the role of circulating tumour cells, extracellular vesicles and their microRNA content, as well as cellular and soluble immunological and inflammation- related blood markers for prostate cancer diagnosis, prognosis and prediction of therapy response is discussed. A special emphasis is placed on markers predicting response to radiotherapy and radiotherapy-related late side effects.
Cognitive User Interface for Portfolio Optimization
Authors: He Yuehuan , Romanko Oleksandr , Sienkiewicz Alina , Seidman Robert , Kwon Roy
Published: April 2021

This paper describes the development of a chatbot as a cognitive user interface for portfolio optimization. The financial portfolio optimization chatbot is proposed to provide an easy-to-use interface for portfolio optimization, including a wide range of investment objectives and flexibility to include a variety of constraints representing investment preferences when compared to existing online automated portfolio advisory services. Additionally, the use of a chatbot interface allows investors lacking a background in quantitative finance and optimization to utilize optimization services. The chatbot is capable of extracting investment preferences from natural text inputs, handling these inputs with a backend financial optimization solver, analyzing the results, and communicating the characteristics of the optimized portfolio back to the user. The architecture and design of the chatbot are presented, along with an implementation using the IBM Cloud, SS&C Algorithmics Portfolio Optimizer, and Slack as an example of this approach. The design and implementation using cloud applications provides scalability, potential performance improvements, and could inspire future applications for financial optimization services.
Polish Culture in the Face of the COVID-19 Pandemic Crisis
Authors: Kantor Angelika , Kubiczek Jakub
Published: April 2021

Cancellation of the events offered by cultural institutions was caused by the restrictions introduced by the government and, at a critical moment, a national lockdown. The COVID-19 pandemic forced cultural institutions to adapt to the new reality. The aim of this article was to present the impact of the pandemic on the activities of cultural institutions, as well as to identify and systematize the activities of such institutions during the pandemic. The following classification, dividing the activities into three groups, has been proposed: virtualization of existing activities, expansion of activities with additional initiatives, and implementation of corporate social responsibility (CSR) initiatives. The greatest challenge was the virtualization of the existing activities and finding new customer markets. The pandemic has contributed to a significant deterioration in the financial situation of cultural institutions because of the reduced income. Long-term effects on cultural institutions may be difficult to predict and losses may be difficult to rebuild.
Consumer Preferences for Labeled Plant-Based Products Associated with Traditional Knowledge: A Study in Protected Natural Areas of Northwest Mexico
Authors: Avilés-Polanco Gerzaín , Almendarez-Hernández Marco Antonio , Beltrán-Morales Luis Felipe , Serrano-Fraire Ileana , Ortega-Rubio Alfredo
Published: April 2021

The use of plants associated with traditional knowledge by pharmaceutical, cosmetic, agro-food, and biotechnology industries represents a potential source of benefits for indigenous groups and local communities within the access and benefit-sharing mechanisms established in the Nagoya Protocol. We used a consumer-choice experiment to evaluate consumer preferences concerning a cosmetic product with attributes related to the traditional knowledge of local plants (efficacy, price, and information). The results indicate that consumers experience higher wellness levels by consuming a cosmetic product with an information label associated with a plant of traditional use. A rise in consumer income increases the likelihood of consuming products with traditional-knowledge attributes. Higher prices are associated with a lower probability of purchase. The random coefficient reveals mixed preferences related to product efficacy level. This work shows the potential demand, by high-income consumers, of cosmetic products labeled with formulation information based on traditional knowledge associated with local plants growing in Protected Natural Areas of northwest Mexico.
How to Define a New Metropolitan Area? The Case of Quito, Ecuador, and Contributions for Urban Planning
Authors: Salazar Esthela , Henríquez Cristián , Durán Gustavo , Qüense Jorge , Puente-Sotomayor Fernando
Published: April 2021

The Metropolitan Area of Quito has experienced exponential growth in recent decades, especially in peri-urban sectors. The literature has described this process as “urban sprawl”, a phenomenon that is changing the landscape by increasing land consumption and forming conurbations with the nearest populated centers. This article proposes a new, broader and more complex metropolitan structure for the metropolis of Quito, the linking of neighboring and conurbed areas to the form a new metropolitan area based on the case study of the Metropolitan District of Quito (DMQ). This new metropolitan area identification considers the interpretation of satellite images and the classification of land uses, highlighting the main urban growth areas located outside, but contiguous to the administrative limit of the DMQ, over a period of 19 years (1998 to 2017), the demographics analysis, particularly the densification of new urban peripheral areas close to the DMQ border and the mobility links of population, goods and services between human settlements that allows the configuration of urban corridors and the integration of the territory. The main findings evaluated are the need to evaluate urban planning strategies aimed at sustainable development.
Modeling Syntactic Change under Contact: The Case of Italiot Greek
Authors: Guardiano Cristina , Stavrou Melita
Published: April 2021

In this paper, we investigate patterns of persistence and change affecting the syntax of nominal structures in Italiot Greek in comparison to Modern (and Ancient) Greek, and we explore the role of Southern Italo-Romance as a potential source of interference. Our aim is to highlight the dynamics that favor syntactic contact in this domain: we provide an overview of the social context where these dynamics have taken place and of the linguistic structures involved.
Sexual Violence against Women, the Laws, the Punishment, and Negotiating the Duplicity
Authors: Cherukuri Suvarna
Published: April 2021

On 16 December 2012, India erupted in national outrage against the rape of a 23-year-old female student in New Delhi, christened “Nirbhaya” (fearless). In the aftermath, there was a convergence of multiple discourses that framed post-independent India’s feminist consciousness. In 2020, four men convicted of Nirbhaya’s rape and murder were executed. An eight-year old girl in Kashmir was brutally raped and murdered in January 2018. The trial court sentenced the main accused to life in prison. In December 2019, four men held in yet another horrific rape and death of a 27-year veterinarian in Hyderabad were killed by the police in what has been called an extrajudicial killing. More recently, in 2020, a 19-year old was raped and killed in rural Uttar Pradesh. The victims came from different social locations, castes, tribes, and religious communities. This paper presents a feminist critique of the legal discourse on rape and the death penalty. It looks at an ironical cooptation of the critique of sexual violence by a patriarchal discourse on social injury and collective conscience. The paper examines how fleeting rage against the culprits and the call for death penalty immunizes larger misogynist cultural assumptions. This myopic rage is oblivious to sexual violence in women’s daily lives. Finally, the paper looks at why legal reforms triggered by brutal acts of sexual violence, receiving widespread media attention, fail to achieve systemic societal changes.
Evaluation of Conserved RNA Secondary Structures within and between Geographic Lineages of Zika Virus
Authors: Nicolas Calderon Kevin , Fabian Galindo Johan , Bermudez-Santana Clara Isabel
Published: April 2021

Zika virus (ZIKV), without a vaccine or an effective treatment approved to date, has globally spread in the last century. The infection caused by ZIKV in humans has changed progressively from mild to subclinical in recent years, causing epidemics with greater infectivity, tropism towards new tissues and other related symptoms as a product of various emergent ZIKV–host cell interactions. However, it is still unknown why or how the RNA genome structure impacts those interactions in differential evolutionary origin strains. Moreover, the genomic comparison of ZIKV strains from the sequence-based phylogenetic analysis is well known, but differences from RNA structure comparisons have barely been studied. Thus, in order to understand the RNA genome variability of lineages of various geographic distributions better, 410 complete genomes in a phylogenomic scanning were used to study the conservation of structured RNAs. Our results show the contemporary landscape of conserved structured regions with unique conserved structured regions in clades or in lineages within circulating ZIKV strains. We propose these structures as candidates for further experimental validation to establish their potential role in vital functions of the viral cycle of ZIKV and their possible associations with the singularities of different outbreaks that lead to ZIKV populations to acquire nucleotide substitutions, which is evidence of the local structure genome differentiation.
Early Prevention of Atherosclerosis: Detection and Management of Hypercholesterolaemia in Children and Adolescents
Authors: Pederiva Cristina , Capra Maria Elena , Viggiano Claudia , Rovelli Valentina , Banderali Giuseppe , Biasucci Giacomo
Published: April 2021

Coronary heart disease (CHD) is the main cause of death and morbidity in the world. There is a strong evidence that the atherosclerotic process begins in childhood and that hypercholesterolaemia is a CHD major risk factor. Hypercholesterolaemia is a modifiable CHD risk factor and there is a tracking of hypercholesterolaemia from birth to adulthood. Familial hypercholesterolaemia (FH) is the most common primitive cause of hypercholesterolaemia, affecting 1:200–250 individuals. Early detection and treatment of hypercholesterolaemia in childhood can literally “save decades of life”, as stated in the European Atherosclerosis Society Consensus. Multiple screening strategies have been proposed. In 2008, the American Academy of Pediatrics published the criteria for targeted screening, while some expert panels recommend universal screening particularly in the young, although cost effectiveness has not been fully analysed. Blood lipid profile evaluation [total cholesterol, Low-Density Lipoprotein Cholesterol (LDL-C), High-Density Lipoprotein Cholesterol (HDL-C) and triglycerides] is the first step. It has to be ideally performed between two and ten years of age. Hypercholesterolaemia has to be confirmed with a second sample and followed by the detection of family history for premature (before 55 years in men and 60 years in women) or subsequent cardio-vascular events and/or hypercholesterolaemia in 1st and 2nd degree relatives. The management of hypercholesterolaemia in childhood primarily involves healthy lifestyle and a prudent low-fat diet, emphasising the benefits of the Mediterranean diet. Statins are the cornerstone of the drug therapy approved in USA and in Europe for use in children. Ezetimibe or bile acid sequestrants may be required to attain LDL-C goal in some patients. Early identification of children with severe hypercholesterolaemia or with FH is important to prevent atherosclerosis at the earliest stage of development, when maximum benefit can still be obtained via lifestyle adaptations and therapy. The purpose of our review is to highlight the importance of prevention and treatment of hypercholesterolaemia starting from the earliest stages of life.
Strategies Regarding High-Temperature Applications w.r.t Strength, Toughness, and Fatigue Life for SA508 Alloy
Authors: Abdullah Muhammad Raies , Hongneng Cai , Liang Fang
Published: April 2021

In this work, the stabilities of secondary phases, including carbides, brittle phases, and inclusions, were simulated by computational thermodynamics. Calphad strategical optimization is preferable for all steel alloys regarding energy resource consumption during manufacturing and processing. The alloy composition has been changed to enhance the strength, hardenability, and longevity of a reactor pressure vessel (RPV) steel by computing the phase equilibrium calculations and predicting mechanical properties such as yield and tensile strengths hardness and martensitic and bainitic volume fractions. The stabilities of the pro-eutectoid carbides (cementite), inclusions, and brittle phases in SA508 steel are critical to the toughness and fatigue life related to the crack initiation and expansion of this steel. Overall, the simulations presented in this paper explain the mechanisms that can affect the fatigue resistance and toughness of steel and offer a possible solution to controlling these properties at elevated temperatures by optimizing the steel composition and heat treatment process parameters.
Formative Assessment of Pre-Service Teachers’ Knowledge on Mathematical Modeling
Authors: Villa-Ochoa Jhony Alexander , Sánchez-Cardona Jonathan , Rendón-Mesa Paula Andrea
Published: April 2021

This document reports how formative assessment strategies promote the knowledge of modeling of pre-service mathematics teachers. This knowledge is understood from content and vehicle points of view. Formative assessment strategies were designed and experimented with 14 participants in a mathematical modeling course offered to pre-service teachers in a Colombian university. Thematic analysis was conducted on lesson plans built by pre-service teachers. In those plans, they evinced knowledge of class management, mathematics teaching, problem solving, and modeling teaching. Finally, the collective construction of assessment rubrics is highlighted. Its contributions and limitations as a formative assessment tool are reported. The role played by the advisors’ feedback and support to pre-service teachers is also presented.
Hadamard Matrices with Cocyclic Core
Authors: Álvarez Víctor , Armario José Andrés , Frau María Dolores , Gudiel Félix , Güemes María Belén , Osuna Amparo
Published: April 2021

Since Horadam and de Launey introduced the cocyclic framework on combinatorial designs in the 1990s, it has revealed itself as a powerful technique for looking for (cocyclic) Hadamard matrices. Ten years later, the series of papers by Kotsireas, Koukouvinos and Seberry about Hadamard matrices with one or two circulant cores introduced a different structured approach to the Hadamard conjecture. This paper is built on both strengths, so that Hadamard matrices with cocyclic cores are introduced and studied. They are proved to strictly include usual Hadamard matrices with one and two circulant cores, and therefore provide a wiser uniform approach to a structured Hadamard conjecture.
Parametric Estimation of Diffusion Processes: A Review and Comparative Study
Authors: López-Pérez Alejandra , Febrero-Bande Manuel , González-Manteiga Wencesalo
Published: April 2021

This paper provides an in-depth review about parametric estimation methods for stationary stochastic differential equations (SDEs) driven by Wiener noise with discrete time observations. The short-term interest rate dynamics are commonly described by continuous-time diffusion processes, whose parameters are subject to estimation bias, as data are highly persistent, and discretization bias, as data are discretely sampled despite the continuous-time nature of the model. To assess the role of persistence and the impact of sampling frequency on the estimation, we conducted a simulation study under different settings to compare the performance of the procedures and illustrate the finite sample behavior. To complete the survey, an application of the procedures to real data is provided.
Convolutional Neural Network–Component Transformation (CNN–CT) for Confirmed COVID-19 Cases
Authors: Frausto-Solís Juan , Hernández-González Lucía J. , González-Barbosa Juan J. , Sánchez-Hernández Juan Paulo , Román-Rangel Edgar
Published: April 2021

The COVID-19 disease constitutes a global health contingency. This disease has left millions people infected, and its spread has dramatically increased. This study proposes a new method based on a Convolutional Neural Network (CNN) and temporal Component Transformation (CT) called CNN–CT. This method is applied to confirmed cases of COVID-19 in the United States, Mexico, Brazil, and Colombia. The CT changes daily predictions and observations to weekly components and vice versa. In addition, CNN–CT adjusts the predictions made by CNN using AutoRegressive Integrated Moving Average (ARIMA) and Exponential Smoothing (ES) methods. This combination of strategies provides better predictions than most of the individual methods by themselves. In this paper, we present the mathematical formulation for this strategy. Our experiments encompass the fine-tuning of the parameters of the algorithms. We compared the best hybrid methods obtained with CNN–CT versus the individual CNN, Long Short-Term Memory (LSTM), ARIMA, and ES methods. Our results show that our hybrid method surpasses the performance of LSTM, and that it consistently achieves competitive results in terms of the MAPE metric, as opposed to the individual CNN and ARIMA methods, whose performance varies largely for different scenarios.
Neoadjuvant Chemohormonal Therapy before Radical Prostatectomy for Japanese Patients with High-Risk Localized Prostate Cancer
Authors: Sasaki Takeshi , Nishikawa Kouhei , Kato Manabu , Masui Satoru , Yoshio Yuko , Sugimura Yoshiki , Inoue Takahiro
Published: April 2021

Background: Radical prostatectomy (RP) is the standard treatment in patients with high-risk prostate cancer (PCa). However, there is a high rate of recurrence, and new approaches are required to improve surgical efficacy. Here, we evaluated the feasibility and safety of neoadjuvant chemohormonal therapy (NCHT) before RP for Japanese patients with high-risk localized prostate cancer (PCa). Methods: From February 2009 to April 2016, 21 high-risk patients were enrolled in this prospective study. Patients were treated with docetaxel (70 mg/m2) every four weeks for three cycles and luteinizing hormone-releasing hormone agonist. Patients with grade 3–4 toxicities had 25% dose reductions for the following course. Results: Median follow-up was 88.6 months. The dose of docetaxel was reduced in 13 patients. The estimated five-year biochemical progression-free survival (bPFS) rate was 57.1%. National Comprehensive Cancer Network criteria (high-risk, but not very high-risk (nVHR) versus VHR) was associated with bPFS (p = 0.03). Five-year bPFS rates in the nVHR and VHR groups were 76.9% and 25.0%, respectively. There was a significant difference in bPFS between the nVHR and VHR groups (p = 0.023) by Kaplan–Meier analysis. Conclusions: Although our study included a small number of cases, at least in our exploration, NCHT was safe and feasible. However, more extensive treatment modalities are needed to improve outcomes, especially in VHR patients.
Influence of Casting Solvents on CO2/CH4 Separation Using Polysulfone Membranes
Authors: Almuhtaseb Roba , Awadallah-F Ahmed , Al-Muhtaseb Shaheen , Khraisheh Majeda
Published: April 2021

Polysulfone membranes exhibit resistance to high temperature with low manufacturing cost and high efficiency in the separation process. The composition of gases is an important step that estimates the efficiency of separation in membranes. As membrane types are currently becoming in demand for CO2/CH4 segregation, polysulfone will be an advantageous alternative to have in further studies. Therefore, research is undertaken in this study to evaluate two solvents: chloroform (CF) and tetrahydrofuran (THF). These solvents are tested for casting polymeric membranes from polysulfone (PSF) to separate every single component from a binary gas mixture of CO2/CH4. In addition, the effect of gas pressure was conducted from 1 to 10 bar on the behavior of the permeability and selectivity. The results refer to the fact that the maximum permeability of CO2 and CH4 for THF is 62.32 and 2.06 barrer at 1 and 2 bars, respectively. Further, the maximum permeability of CF is 57.59 and 2.12 barrer at 1 and 2 bars, respectively. The outcome selectivity values are 48 and 36 for THF and CF at 1 bar, accordingly. Furthermore, the study declares that with the increase in pressure, the permeability and selectivity values drop for CF and THF. The performance for polysulfone (PSF) membrane that is manufactured with THF is superior to that of CF relative to the Robeson upper bound. Therefore, through the results, it can be deduced that the solvent during in-situ synthesis has a significant influence on the gas separation of a binary mixture of CO2/CH4.
Non- and Quasi-Equilibrium Multi-Phase Field Methods Coupled with CALPHAD Database for Rapid-Solidification Microstructural Evolution in Laser Powder Bed Additive Manufacturing Condition
Authors: Nomoto Sukeharu , Segawa Masahito , Watanabe Makoto
Published: April 2021

A solidification microstructure is formed under high cooling rates and temperature gradients in powder-based additive manufacturing. In this study, a non-equilibrium multi-phase field method (MPFM), based on a finite interface dissipation model, coupled with the Calculation of Phase Diagram (CALPHAD) database, was developed for a multicomponent Ni alloy. A quasi-equilibrium MPFM was also developed for comparison. Two-dimensional equiaxed microstructural evolution for the Ni (Bal.)-Al-Co-Cr-Mo-Ta-Ti-W-C alloy was performed at various cooling rates. The temperature-γ fraction profiles obtained under 105 K/s using non- and quasi-equilibrium MPFMs were in good agreement with each other. Over 106 K/s, the differences between the non- and quasi-equilibrium methods grew as the cooling rate increased. The non-equilibrium solidification was strengthened over a cooling rate of 106 K/s. Columnar-solidification microstructural evolution was performed at cooling rates of 5 × 105 K/s to 1 × 107 K/s at various temperature gradient values under a constant interface velocity (0.1 m/s). The results show that, as the cooling rate increased, the cell space decreased in both methods, and the non-equilibrium MPFM was verified by comparing with the quasi-equilibrium MPFM. Our results show that the non-equilibrium MPFM showed the ability to simulate the solidification microstructure in powder bed fusion additive manufacturing.
Effects of Excessive Zr Content and Ultrasonic Treatment on Microstructure and Mechanical Properties of Al-Zn-Mg-Cu Alloy
Authors: Li Cheng , Wu Shusen , Lü Shulin , Li Jianyu , Liu Longfei , Xia Lanqing
Published: April 2021

The Zr element is one of the important grain refiners for 7xxx series Al-Zn-Mg-Cu alloys, but the effect of Zr content more than 0.15 wt.% needs to be deeply investigated under the action of ultrasonic vibration. In this study, the effects of Zr contents (0.1 to 0.25 wt.%) on microstructure and mechanical properties of Al-Zn-Mg-Cu alloy were studied. The results showed that Zr element could refine grains, but when the Zr content was greater than 0.15 wt.%, the grain size was not uniform, the number of second phase particles increased, and the segregation of components became more serious. It was found that after ultrasonic treatment, the grain-size inhomogeneity was greatly improved, and the Zr content could be added up to 0.2 wt.%. When the Zr content is equal or lower than 0.2 wt.%, ultrasonic treatment can effectively improve the mechanical properties of materials by refining grains and weakening segregation. However, when the Zr content is up to 0.25 wt.%, the effect is getting worse.
Microstructure and Mechanical Properties of High Relative Density γ-TiAl Alloy Using Irregular Pre-Alloyed Powder
Authors: Yan Mengjie , Yang Fang , Lu Boxin , Chen Cunguang , Sui Yanli , Guo Zhimeng
Published: April 2021

Preparing high relative density γ-TiAl alloy by pressure-less sintering at low-cost has always been a challenge. Therefore, a new kind of non-spherical pre-alloyed TiAl powder was prepared by the reaction of TiH2 powder and Al powder at 800 °C to fabricate high-density Ti-48Al alloy via pressure-less sintering. The oxygen content was controlled to below 1800 ppm by using coarse Al powder (~120 μm). The sintered densities ranged from 92.1% to 97.5% with sintering temperature varying from 1300 °C to 1450 °C. The microstructure of the sintered compact was greatly influenced by the sintering temperature. The as-sintered samples had a near-γ structure at 1350 °C, a duplex structure at 1400 °C, and a nearly lamellar structure at 1450 °C. To achieve full densification, non-capsule hot isostatic pressing was performed on the 1350 °C and 1400 °C sintered samples. As a result, high compressive strengths of 2241 MPa and 1931MPa were obtained, which were higher than the existing Ti-48Al alloys.
Tube Drawing with Tilted Die: Texture, Dislocation Density and Mechanical Properties
Authors: Al-Hamdany Nowfal , Salih Mohammed Zakria , Palkowski Heinz , Carradò Adele , Gan Weimin , Schell Norbert , Brokmeier Heinz-Günter
Published: April 2021

Anisotropic behavior is a key characteristic for understanding eccentricity in tubes. In this paper, the effect of using a tilted die during tube drawing on eccentricity, texture, dislocation density, and mechanical properties is shown. Copper tubes were drawn with a ±5° tilted die for two passes. The increase or decrease in eccentricity can be controlled by controlling the angle of the tilted die. Two types of textures have been developed during tube drawing, namely plane strain and uniaxial types. Plain strain type texture is mainly characterized by the β fiber with a dominant copper component {112}<111>. The uniaxial deformation type is dominated by the <111> fiber, as commonly found by wire drawing. Texture sharpness increases with increasing drawing strain, and the texture varies significantly between the maximum and minimum wall thickness. This texture variation between maximum and minimum wall thickness has no significant influence on mechanical properties, which are more or less similar, but the increase in strength after each drawing pass is apparent. The dislocation density is low for the as-received tubes due to recovery and recrystallization. This is consistent with the as-received texture dominated by the cube component {001}<100>. During tube drawing, dislocation density increases as a function of the deformation strain. The variation of dislocation density between the maximum and minimum wall thickness in the tube deformed with −5° tilted die is higher than the variation in the tube deformed with +5° tilted die.
Research on Automated Defect Classification Based on Visual Sensing and Convolutional Neural Network-Support Vector Machine for GTA-Assisted Droplet Deposition Manufacturing Process
Authors: Ma Chen , Dang Haifei , Du Jun , He Pengfei , Jiang Minbo , Wei Zhengying
Published: April 2021

This paper proposes a novel metal additive manufacturing process, which is a composition of gas tungsten arc (GTA) and droplet deposition manufacturing (DDM). Due to complex physical metallurgical processes involved, such as droplet impact, spreading, surface pre-melting, etc., defects, including lack of fusion, overflow and discontinuity of deposited layers always occur. To assure the quality of GTA-assisted DDM-ed parts, online monitoring based on visual sensing has been implemented. The current study also focuses on automated defect classification to avoid low efficiency and bias of manual recognition by the way of convolutional neural network-support vector machine (CNN-SVM). The best accuracy of 98.9%, with an execution time of about 12 milliseconds to handle an image, proved our model can be enough to use in real-time feedback control of the process.
Inhibition of Primary Photosynthesis in Desiccating Antarctic Lichens Differing in Their Photobionts, Thallus Morphology, and Spectral Properties
Authors: Barták Miloš , Hájek Josef , Orekhova Alla , Villagra Johana , Marín Catalina , Palfner Götz , Casanova-Katny Angélica
Published: April 2021

Five macrolichens of different thallus morphology from Antarctica (King George Island) were used for this ecophysiological study. The effect of thallus desiccation on primary photosynthetic processes was examined. We investigated the lichens’ responses to the relative water content (RWC) in their thalli during the transition from a wet (RWC of 100%) to a dry state (RWC of 0%). The slow Kautsky kinetics of chlorophyll fluorescence (ChlF) that was recorded during controlled dehydration (RWC decreased from 100 to 0%) and supplemented with a quenching analysis revealed a polyphasic species-specific response of variable fluorescence. The changes in ChlF at a steady state (Fs), potential and effective quantum yields of photosystem II (FV/FM, ΦPSII), and nonphotochemical quenching (NPQ) reflected a desiccation-induced inhibition of the photosynthetic processes. The dehydration-dependent fall in FV/FM and ΦPSII was species-specific, starting at an RWC range of 22–32%. The critical RWC for ΦPSII was below 5%. The changes indicated the involvement of protective mechanisms in the chloroplastic apparatus of lichen photobionts at RWCs of below 20%. In both the wet and dry states, the spectral reflectance curves (SRC) (wavelength 400–800 nm) and indices (NDVI, PRI) of the studied lichen species were measured. Black Himantormia lugubris showed no difference in the SRCs between wet and dry state. Other lichens showed a higher reflectance in the dry state compared to the wet state. The lichen morphology and anatomy data, together with the ChlF and spectral reflectance data, are discussed in relation to its potential for ecophysiological studies in Antarctic lichens.
Differences in Immune Response and Biochemical Parameters of Mice Fed by Kefir Milk and Lacticaseibacillus paracasei Isolated from the Kefir Grains
Authors: Karaffová Viera , Mudroňová Dagmar , Mad’ar Marián , Hrčková Gabriela , Faixová Dominika , Gancarčíková Soňa , Ševčíková Zuzana , Nemcová Radomíra
Published: April 2021

The health benefits of kefir consumption have been well-known for hundreds of years. The objective of this study was to investigate the effect of kefir milk and the probiotic strain Lacticaseibacillus paracasei Ž2 isolated from kefir grains on the immune response and selected parameters of the lipid and liver enzymatic profiles of mice. Mice fed with kefir milk showed significantly increased phagocytic activity and percentages of B cells in the blood and increased gene expression for mucins and percentages of CD8+ lymphocytes in the gut. By applying kefir, we achieved a significant reduction in serum LDL cholesterol and an LDL/HDL ratio that favored an increase in HDL cholesterol. Regarding the hepatic enzymes, in particular a significant reduction in ALT activity was observed. L. paracasei Ž2 alone stimulated the immune response more markedly compared with kefir milk. Regarding the systemic level, we observed increases in the proportion of all T cells (CD3+), CD4+ lymphocytes and the ratio of CD4+:CD8+ cells, and regarding the local intestinal level we noted a significant increase in gene expression for mucins (MUC-1 and MUC-2) and IgA. Moreover, we confirmed the formation of a biofilm on the surface of the forestomach only after the application of L. paracasei Ž2 alone, but not after kefir administration. The results confirmed the hypothesis that the final effect of the probiotic does not correspond with the effect of the individual strain but is the result of mutual interactions of the microorganisms presented in a preparation, and therefore in the case of multi-strain probiotics, in vivo testing of the complex preparation is necessary.
Probiotic and Metabolic Characterization of Vaginal Lactobacilli for a Potential Use in Functional Foods
Authors: D’Alessandro Margherita , Parolin Carola , Bukvicki Danka , Siroli Lorenzo , Vitali Beatrice , De Angelis Maria , Lanciotti Rosalba , Patrignani Francesca
Published: April 2021

The main aim of this work was to verify the metabolic and functional aptitude of 15 vaginal strains belonging to Lactobacillus crispatus, Lactobacillus gasseri, and Limosilactobacillus vaginalis (previously Lactobacillus vaginalis), already characterized for their technological and antimicrobial properties. In order to evaluate the metabolic profile of these vaginal strains, a phenotype microarray analysis was performed on them. Functional parameters such as hydrophobicity, auto-aggregation, deconjugation of bile salts, adhesion to an intestinal cell line (Caco-2), and a simulated digestion process were evaluated for these strains. A good number of these strains showed hydrophobicity values higher than 70%. Regarding the auto-aggregation assay, the most promising strains were L. crispatus BC9 and BC1, L. gasseri BC10 and BC14, and L. vaginalis BC17. Moreover, L. crispatus BC4, BC6, BC7, and BC8 were characterized by strong bile salts hydrolase activity (BHS). In addition, L. crispatus BC8 and L. vaginalis BC17 were characterized by a medium ability to adhere to Caco-2 cells. Data related to digestion process showed a strong ability of vaginal lactobacilli to withstand this stress. In conclusion, the data collected show the metabolic versatility and several exploitable functional properties of the investigated vaginal lactobacilli.
The Role of Bifidobacteria in Predictive and Preventive Medicine: A Focus on Eczema and Hypercholesterolemia
Authors: Marras Luisa , Caputo Michele , Bisicchia Sonia , Soato Matteo , Bertolino Giacomo , Vaccaro Susanna , Inturri Rosanna
Published: April 2021

Bifidobacteria colonize the human gastrointestinal tract early on in life, their interaction with the host starting soon after birth. The health benefits are strain specific and could be due to the produced polysaccharides. The consumption of probiotics may prevent obesity, irritable bowel syndrome, eczema or atopic dermatitis, and asthma. Non-replicative strains of Bifidobacterium longum (NCC3001 and NCC2705) promote the differentiation of normal human epidermal keratinocytes (NHEKs), inducing a high expression of differentiation markers (keratin —KRT1—, and transglutaminase —TGM1—) and pro-regeneration markers (cathepsins), including β-defensin-1, which plays an important role in modulating the cutaneous immune response. Strains belonging to the genera Bifidobacterium and Lactobacillus can increase tight-junction proteins in NHEKs and enhance barrier function. Bifidobacteria and lactobacilli may be used as prophylactic or therapeutic agents towards enteric pathogens, antibiotic-associated diarrhea, lactose intolerance, ulcerative colitis, irritable bowel syndrome, colorectal cancer, cholesterol reduction, and control of obesity and metabolic disorders. Bifidobacterium bifidum showed an in vitro capability of lowering cholesterol levels thanks to its absorption into the bacterial membrane. Several strains of the species Lactobacillus acidophilus, L. delbrueckii subsp. bulgaricus, L. casei, and L. gasseri led to a reduced amount of serum cholesterol due to their ability to assimilate cholesterol (in vitro). Lactococcus lactis KF147 and Lactobacillus plantarum Lp81 have also been shown to reduce cholesterol levels by 12%. Clarifying the specific health mechanisms of Bifidobacterium and Lactobacillus strains in preventing high-cost pathologies could be useful for delineating effective guidelines for the treatment of infants and adults.
Intra- and Inter-Annual Variability in the Dissolved Inorganic Nitrogen in an Urbanized River before and after Wastewater Treatment Plant Upgrades: Case Study in the Grand River (Southwestern Ontario)
Authors: Cejudo Eduardo , Rosamond Madeline S. , Elgood Richard J. , Schiff Sherry L.
Published: April 2021

External nitrogen (N) inputs originating from human activities act as essential nutrients accumulation in aquatic ecosystems or it is exported elsewhere, where the assimilation capacity is surpassed. This research presents a multi-annual case study of the dissolved inorganic nitrogen (DIN) in an urban river in Ontario (Canada), assessed changes in N downstream of the largest wastewater treatment plant (WTP) in the watershed. Changes in the DIN effluent discharge, in-river concentrations and loads were observed comparing the intra- and inter-annual variability (2010–2013) before, during and after WTP upgrades. These upgrades reduced the ammonium concentration in the river from 0.44 to 0.11 mg N-NH4+/L (year average), but the N load in the effluent increased. In the river, nitrate and ammonium concentrations responded to seasonal variability, being higher during the low temperature (>10 °C) and high flow seasons (spring and spring melt). Among years, changes in the DIN concentration are likely controlled by the effluent to river dilution ratio, which variability resides on the differences in river discharge between years. This suggest that the increasing trend in the DIN concentration and loads are the result of agricultural and urban additions, together with reduced N assimilation, in addition to N loads responding to variable river discharge. Finally, we propose monitoring both concentrations and loads, as they provide answers to different questions for regulatory agencies and water managers, allowing tailored strategies for different purposes, objectives and users.