bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular and Morphological Characterization of Colaconema formosanum sp. nov. (Colaconemataceae, Rhodophyta)—A New Endophytic Filamentous Red Algal Species from Taiwan
Authors: Lee Meng-Chou , Yeh Han-Yang
Published: July 2021

The genus Colaconema, containing endophytic algae associated with economically important macroalgae, is common around the world, but has rarely been reported in Taiwan. A new species, C. formosanum, was found attached to an economically important local macroalga, Sarcodia suae, in southern Taiwan. The new species was confirmed based on morphological observations and molecular analysis. Both the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (rbcL) and cytochrome c oxidase subunit I (COI-5P) genes showed high genetic variation between our sample and related species. Anatomical observations indicated that the new species presents asexual reproduction by monospores, cylindrical cells, irregularly branched filaments, a single pyrenoid, and single parietal plastids. Our research supports the taxonomic placement of C. formosanum within the genus Colaconema. This study presents the third record of the Colaconema genus in Taiwan.
Association of Kidney Disease, Potassium, and Cardiovascular Risk Factor Prevalence with Coronary Arteriosclerotic Burden, by Sex
Authors: Lizama Patricio Maragaño , Ríos Diana L. , Cachinero Isaac Subirana , Lopez-Egea Andrea Toloba , Camps Anna , Belzares Oward , Pacheco Claudio , Cerro Cristina , Wehinger Sergio , Fuentes Eduardo , Marrugat Jaume , Palomo Iván
Published: July 2021

The present study aimed to determine the relationship between the prevalence of cardiovascular risk factors and the number and severity of coronary artery atherosclerotic lesions obtained by coronary angiography. We reviewed and analyzed 1642 records from consecutive patients at the Catheter Laboratory of Talca Regional Hospital in Chile between March 2018 and May 2019. Patients were stratified according to the presence and severity of atherosclerotic lesions: 632 (38.5%) had no lesions or <30% stenosis and 1010 (61.5%) had at least one coronary atherosclerotic lesion with ≥30% stenosis (CALS-30). CALS-30 was more frequent in males, smokers, and patients with diabetes and/or hypertension (all p-values < 0.02). Serum potassium, glycaemia, creatinine and glomerular filtration rates were also associated with CALS-30 (all p-values < 0.01) in males. The age and the proportion of males with CALS-30 increased with the number of risk factors (p-values for trends < 0.001). Our results showed a stronger association between the accumulation of risk factors and CALS-30 in women than in men. Serum potassium levels were inversely associated with CALS-30 in men but not in women.
Deep Learning Algorithm for Management of Diabetes Mellitus via Electrocardiogram-Based Glycated Hemoglobin (ECG-HbA1c): A Retrospective Cohort Study
Authors: Lin Chin-Sheng , Lee Yung-Tsai , Fang Wen-Hui , Lou Yu-Sheng , Kuo Feng-Chih , Lee Chia-Cheng , Lin Chin
Published: July 2021

Background: glycated hemoglobin (HbA1c) provides information on diabetes mellitus (DM) management. Electrocardiography (ECG) is a noninvasive test of cardiac activity that has been determined to be related to DM and its complications. This study developed a deep learning model (DLM) to estimate HbA1c via ECG. Methods: there were 104,823 ECGs with corresponding HbA1c or fasting glucose which were utilized to train a DLM for calculating ECG-HbA1c. Next, 1539 cases from outpatient departments and health examination centers provided 2190 ECGs for initial validation, and another 3293 cases with their first ECGs were employed to analyze its contributions to DM management. The primary analysis was used to distinguish patients with and without mild to severe DM, and the secondary analysis was to explore the predictive value of ECG-HbA1c for future complications, which included all-cause mortality, new-onset chronic kidney disease (CKD), and new-onset heart failure (HF). Results: we used a gender/age-matching strategy to train a DLM to achieve the best AUCs of 0.8255 with a sensitivity of 71.9% and specificity of 77.7% in a follow-up cohort with correlation of 0.496 and mean absolute errors of 1.230. The stratified analysis shows that DM presented in patients with fewer comorbidities was significantly more likely to be detected by ECG-HbA1c. Patients with higher ECG-HbA1c under the same Lab-HbA1c exhibited worse physical conditions. Of interest, ECG-HbA1c may contribute to the mortality (gender/age adjusted hazard ratio (HR): 1.53, 95% conference interval (CI): 1.08–2.17), new-onset CKD (HR: 1.56, 95% CI: 1.30–1.87), and new-onset HF (HR: 1.51, 95% CI: 1.13–2.01) independently of Lab-HbA1c. An additional impact of ECG-HbA1c on the risk of all-cause mortality (C-index: 0.831 to 0.835, p < 0.05), new-onset CKD (C-index: 0.735 to 0.745, p < 0.01), and new-onset HF (C-index: 0.793 to 0.796, p < 0.05) were observed in full adjustment models. Conclusion: the ECG-HbA1c could be considered as a novel biomarker for screening DM and predicting the progression of DM and its complications.
Predicting 1-Year Mortality after Hip Fracture Surgery: An Evaluation of Multiple Machine Learning Approaches
Authors: Forssten Maximilian Peter , Bass Gary Alan , Ismail Ahmad Mohammad , Mohseni Shahin , Cao Yang
Published: July 2021

Postoperative death within 1 year following hip fracture surgery is reported to be up to 27%. In the current study, we benchmarked the predictive precision and accuracy of the algorithms support vector machine (SVM), naïve Bayes classifier (NB), and random forest classifier (RF) against logistic regression (LR) in predicting 1-year postoperative mortality in hip fracture patients as well as assessed the relative importance of the variables included in the LR model. All adult patients who underwent primary emergency hip fracture surgery in Sweden, between 1 January 2008 and 31 December 2017 were included in the study. Patients with pathological fractures and non-operatively managed hip fractures, as well as those who died within 30 days after surgery, were excluded from the analysis. A LR model with an elastic net regularization were fitted and compared to NB, SVM, and RF. The relative importance of the variables in the LR model was then evaluated using the permutation importance. The LR model including all the variables demonstrated an acceptable predictive ability on both the training and test datasets for predicting one-year postoperative mortality (Area under the curve (AUC) = 0.74 and 0.74 respectively). NB, SVM, and RF tended to over-predict the mortality, particularly NB and SVM algorithms. In contrast, LR only over-predicted mortality when the predicted probability of mortality was larger than 0.7. The LR algorithm outperformed the other three algorithms in predicting 1-year postoperative mortality in hip fracture patients. The most important predictors of 1-year mortality were the presence of a metastatic carcinoma, American Society of Anesthesiologists(ASA) classification, sex, Charlson Comorbidity Index (CCI) ≤ 4, age, dementia, congestive heart failure, hypertension, surgery using pins/screws, and chronic kidney disease.
The Coaching Black Box: Risk Mitigation during Change Management
Authors: Percy William , Dow Kevin
Published: July 2021

A case study of strategic renewal in the Chinese education market, this paper explores a non-directive coaching model and its impact on risk mitigation, knowledge exchange and innovation in strategic renewal through the application of multi-tiered coaching and manager coaches. Through an ethnographic action research methodology, we ask “Can coaching mitigate organisational risk and increase the likelihood of positive outcomes in change management?” and “Can managers, acting as internal coaches, increase knowledge socialisation and mitigate risk in the change management process?” The paper finds that there is no inherent failure rate in the change management process and that a strategic management approach can mitigate risk liberating managers and organisations to seek to create the collaborative environments that support organisational learning and strategic renewal, thus moving beyond a narrative of failure to one of strategic empowerment and a strategic management approach to risk mitigation. We conclude that a data-driven approach to organisational learning and Professional Learning Communities helps teams to ask the right questions and to mitigate risk through better aligning the organisation to its strategic reality, exploiting organisational learning to achieve competitive advantage and ensuring that systems and processes continue to match the emerging strategic reality.
Influence of Different Types of Corticosteroids on Heart Rate Variability of Individuals with Duchenne Muscular Dystrophy—A Pilot Cross Sectional Study
Authors: Dias Rodrigo Martins , Hoshi Rosangela Akemi , Vanderlei Luiz Carlos Marques , Monteiro Carlos Bandeira de Mello , Alvarez Mayra Priscila Boscolo , Crocetta Tânia Brusque , Grossklauss Luis Fernando , Fernani Deborah Cristina Gonçalves Luiz , Dantas Maria Tereza Artero Prado , Martins Fabiana Paula Almeida , Garner David M. , Abreu Luiz Carlos , Ferreira Celso , da Silva Talita Dias
Published: July 2021

Individuals with Duchenne Muscular Dystrophy (DMD) have an impairment of cardiac autonomic function categorized by parasympathetic reduction and sympathetic predominance. The objective of this study was to assess the cardiac autonomic modulation of individuals with DMD undergoing therapy with Prednisone/Prednisolone and Deflazacort and compare with individuals with DMD without the use of these medications and a typically developed control group. Methods: A cross-sectional study was completed, wherein 40 boys were evaluated. The four treatment groups were: Deflazacort; Prednisone/Prednisolone; no corticoid use; and typical development. Heart Rate Variability (HRV) was investigated via linear indices (Time Domain and Frequency Domain) and non-linear indices Results: The results of this study revealed that individuals with DMD undertaking pharmacotherapies with Prednisolone demonstrated HRV comparable to the Control Typically Developed (CTD) group. In contrast, individuals with DMD undergoing pharmacotherapies with Deflazacort achieved lower HRV, akin to individuals with DMD without any medications, as demonstrated in the metrics: RMSSD; LF (n.u.), HF (n.u.), LF/HF; SD1, α1, and α1/α2, and a significant effect for SD1/SD2; %DET and Ratio; Shannon Entropy, 0 V%, 2 LV% and 2 ULV%. Conclusions: Corticosteroids have the potential to affect the cardiac autonomic modulation in adolescents with DMD. The use of Prednisone/Prednisolone appears to promote improved responses in terms of sympathovagal activity as opposed to Deflazacort.
Mapping QTLs for Breast Muscle Weight in an F2 Intercross between Native Japanese Nagoya and White Plymouth Rock Chicken Breeds
Authors: Ishikawa Akira , Essa Bothaina H. , Nasr Sherif M. , Suzuki Sae
Published: July 2021

Nagoya (NAG), a native Japanese chicken breed, has high quality meat but low meat yield, whereas White Plymouth Rock (WPR), a parental breed of commercial broilers, has rapid growth but high body fat. We previously reported three quantitative trait loci (QTLs) for early postnatal growth in 239 F2 chickens between NAG and WPR breeds. In this study, using the same F2 chickens at 4 weeks of age, we performed genome-wide QTL analysis for breast muscle weight, fat weight and serum and liver levels of biochemical parameters. Two significant QTLs for pectoralis minor and/or major weights were revealed on chromosome 2 between 108 Mb and 127 Mb and chromosome 4 between 10 Mb and 68 Mb. However, no QTL for the other traits was detected. The two QTLs explained 7.0–11.1% of the phenotypic variances, and their alleles derived from WPR increased muscle weights. The chromosome 2 QTL may be a novel locus, whereas the chromosome 4 QTL coincided with a known QTL for meat quality. The findings provide information that is beneficial for genetic improvement of meat yield for the lean NAG breed and, furthermore, provide a better understanding of the genetic basis of chicken muscle development.
A Comprehensive Analysis of Hungarian MODY Patients—Part I: Gene Panel Sequencing Reveals Pathogenic Mutations in HNF1A, HNF1B, HNF4A, ABCC8 and INS Genes
Authors: Gaál Zsolt , Szűcs Zsuzsanna , Kántor Irén , Luczay Andrea , Tóth-Heyn Péter , Benn Orsolya , Felszeghy Enikő , Karádi Zsuzsanna , Madar László , Balogh István
Published: July 2021

Maturity-onset diabetes of the young (MODY) has about a dozen known causal genes to date, the most common ones being HNF1A, HNF4A, HNF1B and GCK. The phenotype of this clinically and genetically heterogeneous form of diabetes depends on the gene in which the patient has the mutation. We have tested 450 Hungarian index patients with suspected MODY diagnosis with Sanger sequencing and next-generation sequencing and found a roughly 30% positivity rate. More than 70% of disease-causing mutations were found in the GCK gene, about 20% in the HNF1A gene and less than 10% in other MODY-causing genes. We found 8 pathogenic and 9 likely pathogenic mutations in the HNF1A gene in a total of 48 patients and family members. In the case of HNF1A-MODY, the recommended first-line treatment is low dose sulfonylurea but according to our data, the majority of our patients had been on unnecessary insulin therapy at the time of requesting their genetic testing. Our data highlights the importance of genetic testing in the diagnosis of MODY and the establishment of the MODY subtype in order to choose the most appropriate treatment.
The Effect of Hydrogen on the Stress-Strain Response in Fe3Al: An ab initio Molecular-Dynamics Study
Authors: Šesták Petr , Friák Martin , Šob Mojmír
Published: July 2021

We performed a quantum-mechanical molecular-dynamics (MD) study of Fe3Al with and without hydrogen atoms under conditions of uniaxial deformation up to the point of fracture. Addressing a long-lasting problem of hydrogen-induced brittleness of iron-aluminides under ambient conditions, we performed our density-functional-theory (DFT) MD simulations for T = 300 K (room temperature). Our MD calculations include a series of H concentrations ranging from 0.23 to 4 at.% of H and show a clear preference of H atoms for tetrahedral-like interstitial positions within the D03 lattice of Fe3Al. In order to shed more light on these findings, we performed a series of static lattice-simulations with the H atoms located in different interstitial sites. The H atoms in two different types of octahedral sites (coordinated by either one Al and five Fe atoms or two Al and four Fe atoms) represent energy maxima. Our structural relaxation of the H atoms in the octahedral sites lead to minimization of the energy when the H atom moved away from this interstitial site into a tetrahedral-like position with four nearest neighbors representing an energy minimum. Our ab initio MD simulations of uniaxial deformation along the ⟨001⟩ crystallographic direction up to the point of fracture reveal that the hydrogen atoms are located at the newly-formed surfaces of fracture planes even for the lowest computed H concentrations. The maximum strain associated with the fracture is then lower than that of H-free Fe3Al. We thus show that the hydrogen-related fracture initiation in Fe3Al in the case of an elastic type of deformation as an intrinsic property which is active even if all other plasticity mechanism are absent. The newly created fracture surfaces are partly non-planar (not atomically flat) due to thermal motion and, in particular, the H atoms creating locally different environments.
Design, Synthesis, and In Vitro Antiproliferative Activity of Hydantoin and Purine Derivatives with the 4-Acetylphenylpiperazinylalkyl Moiety
Authors: Zagórska Agnieszka , Czopek Anna , Jaromin Anna , Mielczarek-Puta Magdalena , Struga Marta , Stary Dorota , Bajda Marek
Published: July 2021

Cancer represents one of the most serious health problems and the second leading cause of death around the world. Heterocycles, due to their prevalence in nature as well as their structural and chemical diversity, play an immensely important role in anti-cancer drug discovery. In this paper, a series of hydantoin and purine derivatives containing a 4-acetylphenylpiperazinylalkyl moiety were designed, synthesized, and biologically evaluated for their anticancer activity on selected cancer cell lines (PC3, SW480, SW620). Compound 4, a derivative of 3′,4′-dihydro-2′H-spiro[imidazolidine-4,1′-naphthalene]-2,5-dione, was the most effective against SW480, SW620, and PC3 cancer cell lines. Moreover, 4 has high tumor-targeting selectivity. Based on docking studies, it was concluded that R isomers of 3′,4′-dihydro-2′H-spiro[imidazolidine-4,1′-naphthalene]-2,5-dione could be further studied as promising scaffolds for the development of thymidine phosphorylase inhibitors.
Surface Adsorption of the Cancer Biomarker Lysophosphatidic Acid in Serum Studied by Acoustic Wave Biosensor
Authors: De La Franier Brian , Thompson Michael
Published: July 2021

The thickness shear mode acoustic wave device is of interest for the sensing of biomarkers for diseases in various biological fluids, but suffers from the issue of non-specific adsorption of compounds other than those of interest to the electrode surface, thus affecting the device’s output. The aim of this present study was to determine the level of non-specific adsorption on gold electrodes from serum samples with added ovarian cancer biomarker lysophosphatidic acid in the presence of a surface anti-fouling layer. The latter was an oligoethylene molecule with thiol group for attachment to the electrode surface. It was found that the anti-fouling layer had a minimal effect on the level of both adsorption of components from serum and the marker. This result stands in sharp contrast to the analogous monolayer employed for anti-fouling reduction on silica.
Initial Conditioning of Used Cigarette Filters for Their Recycling as Acoustical Absorber Materials
Authors: Gómez Escobar Valentín , Moreno González Celia , Arévalo Caballero María José , Gata Jaramillo Ana Mᵃ
Published: July 2021

Used cigarette butts represent a major and problematic form of waste, due to their abundance, toxicity, and durability. Moreover, the few proposals for their recycling are clearly insufficient, and new ones are welcome. For a new proposal regarding the reuse of used cigarette butts as acoustical absorbers in building construction, previous conditioning of the used butts is performed. This conditioning includes the elimination of moisture and toxic products accumulated in the filter of the cigarettes. Thus, in this work, the moisture content effect in acoustical absorption was analyzed, and a proposal for elimination is made. Moreover, a chemical cleaning procedure is proposed, and its influence on the acoustical behavior of the samples was also analyzed.
Effect of Secondary Carbon Nanofillers on the Electrical, Thermal, and Mechanical Properties of Conductive Hybrid Composites Based on Epoxy Resin and Graphite
Authors: Zambrzycki Marcel , Sokolowski Krystian , Gubernat Maciej , Fraczek-Szczypta Aneta
Published: July 2021

In this work, we present a comparative study of the impact of secondary carbon nanofillers on the electrical and thermal conductivity, thermal stability, and mechanical properties of hybrid conductive polymer composites (CPC) based on high loadings of synthetic graphite and epoxy resin. Two different carbon nanofillers were chosen for the investigation—low-cost multi-layered graphene nanoplatelets (GN) and carbon black (CB), which were aimed at improving the overall performance of composites. The samples were obtained by a simple, inexpensive, and effective compression molding technique, and were investigated by the means of, i.a., scanning electron microscopy, Raman spectroscopy, electrical conductivity measurements, laser flash analysis, and thermogravimetry. The tests performed revealed that, due to the exceptional electronic transport properties of GN, its relatively low specific surface area, good aspect ratio, and nanometric sizes of particles, a notable improvement in the overall characteristics of the composites (best results for 4 wt % of GN; σ = 266.7 S cm−1; λ = 40.6 W mK−1; fl. strength = 40.1 MPa). In turn, the addition of CB resulted in a limited improvement in mechanical properties, and a deterioration in electrical and thermal properties, mainly due to the too high specific surface area of this nanofiller. The results obtained were compared with US Department of Energy recommendations regarding properties of materials for bipolar plates in fuel cells. As shown, the materials developed significantly exceed the recommended values of the majority of the most important parameters, indicating high potential application of the composites obtained.
Utilization of Eco-Friendly Waste Generated Nanomaterials in Water-Based Drilling Fluids; State of the Art Review
Authors: Ikram Rabia , Mohamed Jan Badrul , Sidek Akhmal , Kenanakis George
Published: July 2021

An important aspect of hydrocarbon drilling is the usage of drilling fluids, which remove drill cuttings and stabilize the wellbore to provide better filtration. To stabilize these properties, several additives are used in drilling fluids that provide satisfactory rheological and filtration properties. However, commonly used additives are environmentally hazardous; when drilling fluids are disposed after drilling operations, they are discarded with the drill cuttings and additives into water sources and causes unwanted pollution. Therefore, these additives should be substituted with additives that are environmental friendly and provide superior performance. In this regard, biodegradable additives are required for future research. This review investigates the role of various bio-wastes as potential additives to be used in water-based drilling fluids. Furthermore, utilization of these waste-derived nanomaterials is summarized for rheology and lubricity tests. Finally, sufficient rheological and filtration examinations were carried out on water-based drilling fluids to evaluate the effect of wastes as additives on the performance of drilling fluids.
The Influence of Lime Solution in Kneading Water Substitution on Cement Roughcast and Mortar Coating
Authors: Santos André M. , Silva Ângelo J. Costa e , Mota João M. F. , Delgado João M. P. Q. , Silva Fernando A. N. , Azevedo António C.
Published: July 2021

The understanding of the mechanical fixation behavior of coatings is crucial for a better comprehension of the bonding systems, especially at the interface between the mortar and the substrate. Physical adherence is related, among other things, to the contents of the materials used in the roughcast and mortar coatings, due to the colloidal water penetration into the pores of the substrate. This work evaluated the influence of different lime solution additions replacing the kneading water in the preparation of roughcast and mortar coatings. Two types of substrates were investigated:ceramic bricks and concrete blocks. Three wall masonry panels were constructed, with dimensions of 220 × 180 cm2, one of concrete block and two of ceramic bricks, followed by the application of roughcast and mortar coating with an average thickness of 5 mm and 20 mm, respectively. Direct tensile bond strength tests were performed and the results, with a 95% confidence level, showed that substrate ceramic and treatment in the roughcast exhibited a better behavior regarding the distribution of the tensile bond strength of the tested specimens. However, no significant differences of the amount of addition used (0%, 5%, 10% and 15%) on the tensile bond strength were observed.
Numerical Simulation of Steel-Reinforced Reactive Powder Concrete Beam Based on Bond-Slip
Authors: Li Haoxu , Guo Xiao , Duan Jiqiang
Published: July 2021

In this study, based on the concrete damaged plasticity (CDP) model in the ABAQUS software, various plastic damage factor calculation methods were introduced to obtain CDP parameters suitable for reactive powder concrete (RPC) materials. Combined with the existing tests for the bending performance of steel-reinforced RPC beams, the CDP parameters of the RPC material were input into ABAQUS to establish a finite element model considering the bond and slip between the steel and RPC for numerical simulation. The load-deflection curve obtained by the simulation was compared with the measured curve in the experiment. The results indicated that on the basis of the experimentally measured RPC material eigenvalue parameters, combined with the appropriate RPC constitutive relationship and the calculation method of the plastic damage factor, the numerical simulation results considering the bond-slip were in good agreement with the experimental results with a deviation of less than 10%. Thus, it is recommended to select a gentle compressive stress-strain curve in the descending section, an approximate strengthening model of the tensile stress-strain curve, and to use the energy loss method and Sidoroff’s energy equivalence principle to calculate the RPC plastic damage parameters.
Thermal Decomposition Kinetics and Compatibility of 3,5-difluoro-2,4,6-trinitroanisole (DFTNAN)
Authors: Hu Fei , Wang Lin-Jian , Zhao Wei , Liu Yu-Cun , Jing Su-Ming , Liu Ping , He Jin-Xuan
Published: July 2021

In this paper, the thermal decomposition behavior of 3,5-difluoro-2,4,6-trinitroanisole (DFTNAN) was studied by differential scanning calorimetry (DSC) and thermogravimetry (TG) by using different heating rates (2, 5, 10, 15 °C·min−1). Subsequently, the kinetic and thermodynamic parameters of non-isothermal thermal decomposition of DFTNAN were calculated. The critical temperature of thermal explosion (Tb) and self-accelerating decomposition temperature (TASDT) were determined to be 249.03 °C and 226.33 °C, respectively. The compatibility of DFTNAN with a number of high explosives (cyclo-1,3,5-trimethylene-2,4,6-trinitramine (RDX), 1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaaza-tetracyclo-[5.5.0.05,9.03,11]-dodecane (CL-20) and dihydroxylammonium 5,5’-bistetrazole-1,1’-diolate (TKX-50)) was studied at different mass ratios using DSC. The criteria to judge the compatibility between the materials were based on a standardization agreement (STANAG 4147). The thermodynamic study results revealed that DFTNAN possessed superior thermal safety and stability. The experimental of compatibility results indicated that the mass ratios of the high explosives in the DFTNAN/RDX, DFTNAN/HMX and DFTNAN/CL-20 compositions more than 40%, 60% and 70% exhibited good compatibility, whereas DFTNAN/TKX-50 demonstrated poor compatibility.
Effect of Interlayer Delay on the Microstructure and Mechanical Properties of Wire Arc Additive Manufactured Wall Structures
Authors: Singh Shalini , Jinoop Arackal Narayanan , Tarun Kumar Gorlea Thrinadh Ananthvenkata , Palani Iyamperumal Anand , Paul Christ Prakash , Prashanth Konda Gokuldoss
Published: July 2021

Wire arc additive manufacturing is a metal additive manufacturing technique that allows the fabrication of large size components at a high deposition rate. During wire arc additive manufacturing, multi-layer deposition results in heat accumulation, which raises the preheat temperature of the previously built layer. This causes process instabilities, resulting in deviations from the desired dimensions and variations in material properties. In the present study, a systematic investigation is carried out by varying the interlayer delay from 20 to 80 s during wire arc additive manufacturing deposition of the wall structure. The effect of the interlayer delay on the density, geometry, microstructure and mechanical properties is investigated. An improvement in density, reduction in wall width and wall height and grain refinement are observed with an increase in the interlayer delay. The grain refinement results in an improvement in the micro-hardness and compression strength of the wall structure. In order to understand the effect of interlayer delay on the temperature distribution, numerical simulation is carried out and it is observed that the preheat temperature reduced with an increase in interlayer delay resulting in variation in geometry, microstructure and mechanical properties. The study paves the direction for tailoring the properties of wire arc additive manufacturing-built wall structures by controlling the interlayer delay period.
Sol-Gel Processed Cobalt-Doped Methylated Silica Membranes Calcined under N2 Atmosphere: Microstructure and Hydrogen Perm-Selectivity
Authors: Wang Lunwei , Yang Jing , Mu Ruihua , Guo Yingming , Hou Haiyun
Published: July 2021

Methyl-modified, cobalt-doped silica (Co/MSiO2) materials were synthesized by sol-gel technique calcined in N2 atmospheres, and membranes were made thereof by coating method. The effects of Co/Si molar ratio (nCo) on the physical-chemical constructions of Co/MSiO2 materials and microstructures of Co/MSiO2 membranes were systematically investigated. The gas permeance performance and hydrothermal stability of Co/MSiO2 membranes were also tested. The results show that the cobalt element in Co/MSiO2 material calcined at 400 °C exists not only as Si–O–Co bond but also as Co3O4 and CoO crystals. The introduction of metallic cobalt and methyl can enlarge the total pore volume and average pore size of the SiO2 membrane. The activation energy (Ea) values of H2, CO2, and N2 for Co/MSiO2 membranes are less than those for MSiO2 membranes. When operating at a pressure difference of 0.2 MPa and 200 °C compared with MSiO2 membrane, the permeances of H2, CO2, and N2 for Co/MSiO2 membrane with nCo = 0.08 increased by 1.17, 0.70, and 0.83 times, respectively, and the perm-selectivities of H2/CO2 and H2/N2 increased by 27.66% and 18.53%, respectively. After being steamed and thermally regenerated, the change of H2 permeance and H2 perm-selectivities for Co/MSiO2 membrane is much smaller than those for MSiO2 membrane.
Recycling of Carbon Fiber-Reinforced Composites—Difficulties and Future Perspectives
Authors: Borjan Dragana , Knez Željko , Knez Maša
Published: July 2021

Carbon fiber-reinforced composites present an exciting combination of properties and offer clear advantages that make them a perfect replacement for a spread of materials. Consequently, in recent years, their production has dramatically increased as well as the quantity of waste materials. As future legislations are likely to prevent the use of landfills and incineration to dispose of composite waste, alternative solutions such as recycling are considered as one of the urgent problems to be settled. This study presents the leading technologies for recycling carbon fiber-reinforced composites, focusing on chemical recycling using sub- and supercritical fluids. These new reaction media have been demonstrated to be more manageable and efficient in recovering clean fibers with good mechanical properties. The conventional technologies of carbon fibers recycling have also been reviewed and described with both advantages and drawbacks.
Improvement Prediction on the Dynamic Performance of Epoxy Composite Used in Packaging by Using Nano-Particle Reinforcements in Addition to 2-Hydroxyethyl Methacrylate Toughener
Authors: Chen Chih-Ming , Chang Huey-Ling , Lee Chun-Ying
Published: July 2021

Epoxy with low viscosity and good fluidity before curing has been widely applied in the packaging of electronic and electrical devices. Nevertheless, its low flexibility and toughness renders the requirement of property improvement before it can be widely acceptable in dynamic loading applications. This study investigates the possible use of 2-hydroxyethyl methacrylate (HEMA) toughening agent and nano-powders, such as alumina, silicon dioxide, and carbon black, to form epoxy composites for dynamic property improvement. Considering the different combinations of the nano-powders and HEMA toughener, the Taguchi method with an L9 orthogonal array was adopted for composition optimization. The dynamic storage modulus and loss tangent of the prepared specimen were measured by employing a dynamic mechanical analyzer. With polynomial regression, the curve-fitted relationships of the glass transition temperature and storage modulus with respect to the design factors were obtained. It was found that although the raise in the weight fraction of nano-powders was beneficial in increasing the rigidity of the epoxy composite, an optimal amount of HEMA toughener existed for its best damping improvement.
Shielding Properties of Some Marble Types: A Comprehensive Study of Experimental and XCOM Results
Authors: Elsafi Mohamed , El-Nahal Mohamed A. , Alrashedi M. F. , Olarinoye O. I. , Sayyed M. I. , Khandaker Mayeen Uddin , Osman Hamid , Alamri Sultan , Abbas M. I.
Published: July 2021

In this work, some marble types were collected from Egypt, and their shielding characteristics were estimated. Their rigidity, in addition to their elegant shape, led us to consider their use as a protective shield, in addition to making the workplace more beautiful. The mass attenuation coefficient (μ/ρ) was calculated for three types of marble (Breshia, Galala, and Trista) experimentally, using a narrow gamma ray source and high pure germanium (HPGe). The results obtained were compared with the XCOM program and indicated a very good agreement between the two methods. The linear attenuation coefficient (μ) was evaluated to calculate the half and tenth value layers. The maximum μ value of 1.055, 1.041, and 1.024 cm−1 was obtained for Breshia, Galala, and Trista, respectively, at 0.06 MeV. The mean free path for studying the materials was compared with other shielding materials and showed good results at different energy scales. The energy absorption (EABF) and exposure buildup factors (EBF) were determined at different mean free paths. The fast neutron removal cross section ΣR was calculated and expresses the ability of the marbles to slow down fast neutrons through multiple scattering. This is the ability of the marbles to shield fast neutrons.
Asphalt Mixes Processed with Recycled Concrete Aggregate (RCA) as Partial Replacement of the Natural Aggregate
Authors: Espino-Gonzalez Carlos U. , Martinez-Molina Wilfrido , Alonso-Guzman Elia M. , Chavez-Garcia Hugo L. , Arreola-Sanchez Mauricio , Sanchez-Calvillo Adria , Navarrete-Seras Marco A. , Borrego-Perez Jorge A. , Mendoza-Sanchez Juan F.
Published: July 2021

Materials play a fundamental role in any branch of civil engineering. From ancient times to the present day, society has required enormous amounts of construction materials, which implies an excessive exploitation of the natural environment. The present research work consisted in the design and development of asphalt mixes with a partial substitution of the natural aggregate (NA) by means of recycled concrete aggregate (RCA). The mix was designed with the Marshall methodology, considering the next percentages of substitution and addition by mass: 90% NA and 10% RCA; 80% NA and 20% RCA; 70% NA and 30% RCA. The mixtures were elaborated and analysed under the international standards and the Mexican regulation of the Communications and Transport Ministry, to determine the best option regarding their performance. The materials were characterized according to the current regulations and later employed in the mixes design. A total of 38 specimens were elaborated for each mixture, determining the optimum asphalt content; after that, mechanical tests were performed to analyse and determine the best results. In the aftermath of the examination of all mixtures, we concluded that the 70%AN/30%RCA is the best alternative option according to its performance and numeric results, complying with the cited regulations, and allowing a lower content of asphalt during the process.
Trading Cryptocurrencies as a Pandemic Pastime: COVID-19 Lockdowns and Bitcoin Volume
Authors: Guzmán Alexander , Pinto-Gutiérrez Christian , Trujillo María-Andrea
Published: July 2021

This paper examines the impact of COVID-19 lockdowns on Bitcoin trading volume. Using data from Apple mobility trends and several time-series econometric models, we find that investors became active participants during the COVID-19 pandemic period and traded more bitcoins on days with low mobility associated with lockdown mandates. These results remain robust after controlling for stocks and gold returns, the VIX index, and the level of attention and sentiment toward Bitcoin, as measured by Google search frequencies and the tone of Tweets discussing Bitcoin. These results suggest that when individual investors have ample free time on their hands, they trade cryptocurrencies as a pastime and use the Bitcoin market as a form of entertainment. Moreover, our results have important implications concerning investors’ herding behavior and overconfidence leading to noise trader risks and bubbles typically accompanied by high trading volume in cryptocurrency markets.
The Pet Affection Scale Development, Validation and Influence on Consumers’ Behavior of Pet Hotels
Authors: Lee Yung-Hsin , Lai Chih-Min
Published: July 2021

The purpose of this research was to develop a measurement scale, the Pet Affection Scale (PAS), to understand owners’ personalities and attachment to their pets. The data were collected through two waves. There were 401 valid data collected from the first wave to develop the pet affection scale (PAS). An exploratory factor analysis (EFA) was tested, and three factors were extracted and identified as (1) joy, (2) anthropomorphism, and (3) protection, respectively. Furthermore, 901 valid data collected from the second wave were used to analyze and propose a research model to examine the PAS influence on the owners’ behavioral intention toward pet hotels. These research findings show that all three pet affections have positive significant effects on pet hotels’ behavioral intention. The implications, limitations, and future research of this research were suggested and discussed.
Randomized Simplicial Hessian Update
Authors: Bűrmen Árpád , Tuma Tadej , Olenšek Jernej
Published: July 2021

Recently, a derivative-free optimization algorithm was proposed that utilizes a minimum Frobenius norm (MFN) Hessian update for estimating the second derivative information, which in turn is used for accelerating the search. The proposed update formula relies only on computed function values and is a closed-form expression for a special case of a more general approach first published by Powell. This paper analyzes the convergence of the proposed update formula under the assumption that the points from Rn where the function value is known are random. The analysis assumes that the N+2 points used by the update formula are obtained by adding N+1 vectors to a central point. The vectors are obtained by transforming a prototype set of N+1 vectors with a random orthogonal matrix from the Haar measure. The prototype set must positively span a N≤n dimensional subspace. Because the update is random by nature we can estimate a lower bound on the expected improvement of the approximate Hessian. This lower bound was derived for a special case of the proposed update by Leventhal and Lewis. We generalize their result and show that the amount of improvement greatly depends on N as well as the choice of the vectors in the prototype set. The obtained result is then used for analyzing the performance of the update based on various commonly used prototype sets. One of the results obtained by this analysis states that a regular n-simplex is a bad choice for a prototype set because it does not guarantee any improvement of the approximate Hessian.
Three-Stage Numerical Solution for Optimal Control of COVID-19
Authors: Tamayo Luis Vargas , Mbazumutima Vianney , Thron Christopher , Todjihounde Léonard
Published: July 2021

In this paper, we present a three-stage algorithm for finding numerical solutions for optimal control problems. The algorithm first performs an exhaustive search through a discrete set of widely dispersed solutions which are representative of large subregions of the search space; then, it uses the search results to initialize a Monte Carlo process that searches quasi-randomly for a best solution; then, it finally uses a Newton-type iteration to converge to a solution that satisfies mathematical conditions of local optimality. We demonstrate our methodology on an epidemiological model of the coronavirus disease with testing and distancing controls applied over a period of 180 days to two different subpopulations (low-risk and high-risk), where model parameters are chosen to fit the city of Houston, Texas, USA. In order to enable the user to select his/her preferred trade-off between (number of deaths) and (herd immunity) outcomes, the objective function includes costs for deaths and non-immunity. Optimal strategies are estimated for a grid of (death cost) × (non-immunity cost) combinations, in order to obtain a Pareto curve that represents optimum trade-offs. The levels of the four controls for the different Pareto-optimal solutions over the 180-day period are visually represented and their characteristics discussed. Three different variants of the algorithm are run in order to determine the relative importance of the three stages in the optimization. Results from the three algorithm variants are fairly consistent, indicating that solutions are robust. Results also show that the Monte Carlo stage plays an especially prominent role in the optimization, but that all three stages of the process make significant contributions towards finding lower-cost, more effective control strategies.
The Study of Clinical and Biochemical Parameters in Assessing the Response to the Antiviral Therapy in the Chronic Viral Hepatitis B
Authors: Ghenea Alice Elena , Pădureanu Vlad , Cioboată Ramona , Udriștoiu Anca-Loredana , Drocaş Andrei Ioan , Țieranu Eugen , Carsote Mara , Vasile Corina Maria , Moroşanu Aritina , Biciușcă Viorel , Salan Alex-Ioan , Turculeanu Adriana , Ungureanu Anca
Published: July 2021

Background and Objectives: Hepatitis B virus infection remains a major public health concern. The interaction between hepatitis B virus (HBV) hepatitis B virus and the host inflammatory response is an important contributing factor driving liver damage and diseases outcomes. The management of chronic hepatitis B virus infection is an area of massive unmet clinical need worldwide. Our primary aim for this study was to evaluate biological response rates and sustained virological response in patients with chronic hepatitis B treated with Peg-IFN α-2a/b. The second aim of the study was the identification of metabolic changes and insulin resistance. Materials and Methods: We enrolled in this study 166 patients who fulfilled all inclusion and exclusion criteria. These treatment-naive patients with chronic HBV were treated with Pegylated Interferon α-2a/b. HBV infection was defined by the presence of HBV serological markers (HBsAg, anti-HBsAb, anti-HBcAb, HBeAg, anti HBeAb) by Enzyme-Linked Immuno Sorbent Assay (ELISA) and serum HBV-DNA levels were estimated by a commercially available quantitative polymerase chain reaction (PCR) assay. Results: Patients’ recovery progress has been evaluated by determining the following: age, gender; biochemical tests; alanine aminotransferase, aspartate aminotransferase; serological assays for HBV serological markers (HBsAg, anti-HBsAc/Ab, anti-HBcAc/Ab, HBeAg, anti HBeAc/Ab); molecular tests to detect viral particles, testing for HBV DNA (PCR) to confirm the diagnosis and quantify the number of viral copies in the blood (viremia); liver ultrasound—performed through epigastric and intercostal approach (transversal and longitudinal sections). Conclusions: Our results indicated that only HOMA index values, that of fasting insulin, together with baseline HBV DNA, alanine aminotransferase values, mean blood glucose at the beginning of treatment may be predictive of the early viral response in chronic hepatitis B.
Postoperative Morbidity and Complications in Elderly Patients after Harvesting of Iliac Crest Bone Grafts
Authors: Katz Marie Sophie , Ooms Mark , Heitzer Marius , Peters Florian , Winnand Philipp , Kniha Kristian , Möhlhenrich Stephan Christian , Hölzle Frank , Knobe Matthias , Modabber Ali
Published: July 2021

Background and objectives: In oral and maxillofacial operations, the iliac crest is a commonly used donor site from which to harvest bone for augmentation prior to dental implantation or for reconstruction of jaw defects caused by trauma or pathological lesions. In an aging society, the proportion of elderly patients undergoing iliac crest bone grafting for oral augmentation is growing. Although postoperative morbidity is usually moderate to low, the age and health of the patient should be considered as risk factors for complications and delayed mobilization after the operation. The aim of this retrospective study was to evaluate the postoperative morbidity and complications in elderly patients after the harvesting of iliac crest bone grafts for oral surgery. Material and Methods: Data were collected from a total of 486 patients (aged 7–85) who had a surgical procedure that included the harvesting of iliac crest bone grafts for intraoral transplantation. All patients were operated on between 2005 and 2021 in the Department for Oral and Maxillofacial Surgery of the University Hospital in Aachen, Germany. As parameters for postoperative morbidity and complications, gait disturbances, hypesthesia of cutaneous nerves, incision hernias, iliac crest fractures, delayed wound healing, and unfavorable scar formation at the donor site were all evaluated. Results: The study was performed with 485 patients due to the exclusion of one patient as the only one from whom grafts were taken from both sides. When younger and older patients were compared, neither gait disturbances (p = 0.420), nor hernias (p = 0.239), nor fractures (p = 0.239), nor hypesthesia (p = 0.297), nor wound healing delay (p = 0.294), nor scar problems (p = 0.586) were significantly different. However, the volume of the graft was significantly correlated with the duration of the hospital stay (ρ = 0.30; p < 0.01) but not with gait disturbances (ρ = 0.60; p = 0.597). Additionally, when controlling for age (p = 0.841), sex (p = 0.031), ASA class (p = 0.699), preexisting orthopedic handicaps (p = 0.9828), and the volume of the bone graft (p = 0.770), only male sex was associated with the likelihood of suffering gait disturbances (p = 0.031). Conclusions: In conclusion, harvesting bone grafts from the anterior iliac crest for intraoral augmentation is a safe procedure for both young and elderly patients. Although there is some postoperative morbidity, such as gait disturbances, hypesthesia, scar formation, or delayed wound healing at the donor site, rates for these minor complications are low and mostly of short duration. Major complications, such as fractures or incision hernias, are very rare. However, in our study, the volume of the bone graft was associated with a longer stay in hospital, and this should be considered in the planning of iliac crest bone graft procedures.