bluuebunny/crossref_metadata_2025 huggingface dataset:
Paediatric Partial-Thickness Burn Therapy: A Meta-Analysis and Systematic Review of Randomised Controlled Trials
Authors: Lőrincz Aba , Váradi Alex , Hegyi Péter , Rumbus Zoltán , Tuba Máté , Lamberti Anna Gabriella , Varjú-Solymár Margit , Párniczky Andrea , Erőss Bálint , Garami András , Józsa Gergő
Published: April 2022

Background: Paediatric second-degree burn injuries are a significant source of medical challenges to the population that may cause severe, lifelong complications. Currently, there are dozens of therapeutic modalities and we aimed to summarise their reported outcomes and determine their effectiveness, compared to the widely used silver sulphadiazine (SSD). Methods: We conducted the meta-analysis and systematic review of randomised controlled trials (RCTs), which investigated the performance of dressings in acute paediatric partial-thickness burns. The evaluated endpoints were time until wound closure, grafting and infection rate, number of dressing changes and length of hospitalisation. Results: Twenty-nine RCTs were included in the qualitative and 25 in the quantitative synthesis, but only three trials compared SSD directly to the same intervention (Biobrane). Data analysis showed a tendency for faster healing times and a reduced complication rate linked to biosynthetic, silver foam and amnion membrane dressings. A substantial difference was found between the number of dressing changes associated with less pain, narcosis and treatment duration. Conclusions: Considerable between-study heterogeneity was caused by the unequal depth subcategory ratio and surface area of the injuries; therefore, no significant difference was found in the main outcomes. Further research is necessary to establish the most effective treatment for these burns.
Modeling Virus and Bacteria Populations in Europa’s Subsurface Ocean
Authors: Gomez-Buckley Adriana C. , Showalter Gordon M. , Wong Michael L.
Published: April 2022

The search for life in the universe is often informed by the study of “extreme” environments on Earth, which provide analogs for habitable locations in the Solar System, and whose microbial inhabitants may therefore also serve as analogs for potential life forms in extraterrestrial milieus. Recent work has highlighted the ubiquity and importance of viral entities in terrestrial ecosystems, which calls for a greater understanding of the roles that viruses might play in hypothetical extraterrestrial biomes. While some studies have modeled the dynamics of viral and bacterial populations in icy ocean environments on Earth, previous work has yet to apply these findings to icy ocean worlds such as Jupiter’s moon Europa. It is commonly theorized that hydrothermal vents on Europa could produce the necessary reductants for chemosynthesis to take place on the ocean bottom. In the case that Europa’s ocean is a reductant-limited environment, how might reductants and organic matter reach the sub-ice region to power a more easily accessible ecosystem? Here, we propose a ‘viral elevator,’ a mechanism that functions similarly to the ‘viral shunt’ in Earth’s oceans, which could create and shuttle dissolved organic matter (DOM) to a hypothetical sub-ice biosphere through viral carriers. Current models of Europa’s ocean currents and stratification support the movement of DOM to the sub-ice biosphere. We adapt an existing model for bacterial and viral population dynamics in Earth’s Arctic sea ice to Europa and use parameters from various Arctic-based studies as proxies for Europa’s environment. We find that viral burst size has the most significant effect on the virus-to-bacteria ratio (VBR) and system longevity in closed systems (such as brine pockets within Europa’s icy crust), with higher burst sizes clearly increasing both. When applying our model to an open system with an influx of DOM from the viral elevator, we found that a steady-state system is attainable, with resulting sub-ice biofilms on the order of 0.1 mm thick (global equivalent layer). This has implications for future searches for life on Europa, given that life directly under the ice will be easier to detect and observe than life near the ocean bottom.
Modelling of the Citric Acid Production from Crude Glycerol by Wild-Type Yarrowia lipolytica DSM 8218 Using Response Surface Methodology (RSM)
Authors: Giacomobono Romina , Albergo Roberto , Valerio Vito , Caporusso Antonio , De Bari Isabella
Published: April 2022

Crude glycerol is the main by-product of the biodiesel manufacturing industry (10% w/w). Its use as a substrate in microbial fermentations is a concrete strategy to efficiently address its market surplus. In this study, the conversion of crude glycerol to citric acid, a key biochemical in the emerging bioeconomy, by a wild-type yeast Yarrowia lipolytica DSM 8218 was modelled using the Response Surface Methodology. The model relates C/N mass ratio and crude glycerol concentration to maximize the citric acid yield in flask scale using two different N sources, yeast extract and ammonium sulphate. Under the optimal conditions (yeast extract, C/N 141, glycerol 33 g/L), the conversion yield was 0.249 g/g. The optimal conditions were used for up-scaling a fed-batch fermentation in a 2 L bioreactor highlighting a metabolic shift from mannitol to citric acid when high stirring rates were applied (800 rpm). In these conditions, a morphic transition from pseudo-mycelial form to round-shaped yeast-like cells was observed too.
An Attention-Guided Spatiotemporal Graph Convolutional Network for Sleep Stage Classification
Authors: Li Menglei , Chen Hongbo , Cheng Zixue
Published: April 2022

Sleep staging has been widely used as an approach in sleep diagnoses at sleep clinics. Graph neural network (GNN)-based methods have been extensively applied for automatic sleep stage classifications with significant results. However, the existing GNN-based methods rely on a static adjacency matrix to capture the features of the different electroencephalogram (EEG) channels, which cannot grasp the information of each electrode. Meanwhile, these methods ignore the importance of spatiotemporal relations in classifying sleep stages. In this work, we propose a combination of a dynamic and static spatiotemporal graph convolutional network (ST-GCN) with inter-temporal attention blocks to overcome two shortcomings. The proposed method consists of a GCN with a CNN that takes into account the intra-frame dependency of each electrode in the brain region to extract spatial and temporal features separately. In addition, the attention block was used to capture the long-range dependencies between the different electrodes in the brain region, which helps the model to classify the dynamics of each sleep stage more accurately. In our experiments, we used the sleep-EDF and the subgroup III of the ISRUC-SLEEP dataset to compare with the most current methods. The results show that our method performs better in accuracy from 4.6% to 5.3%, in Kappa from 0.06 to 0.07, and in macro-F score from 4.9% to 5.7%. The proposed method has the potential to be an effective tool for improving sleep disorders.
Fabry’s Disease: The Utility of a Multidisciplinary Screening Approach
Authors: Monte Marco Angelo , Veroux Massimiliano , Rodolico Margherita Stefania , Losi Valentina , Di Pino Luigi , Bella Rita , Lanza Giuseppe , Monte Ines Paola
Published: April 2022

(1) Background: As a lysosomal storage disorder, Fabry’s disease (FD) shows variable clinical manifestations. We applied our multidisciplinary approach to identify any organ damage in a sample of adult patients with different pathogenic variants. (2) Methods: 49 participants (mean age 44.3 ± 14.2 years; 37 females), underwent a multidimensional clinical and instrumental assessment. (3) Results: At diagnosis, mean enzymatic activity was 5.2 ± 4.6 nM/mL/h in females and 1.4 ± 0.5 nM/mL/h in males (normal values > 3.0), whereas globotriaosylsphingosine was 2.3 ± 2.1 nM/L in females and 28.7 ± 3.5 nM/L in males (normal values < 2.0). Overall, cardiovascular, neurological, and audiological systems were the most involved, regardless of the variant detected. Patients with classic variants (10) showed typical multiorgan involvement and, in some cases, prevalent organ damage (cardiovascular, neurological, renal, and ocular). Those with late-onset variants (39) exhibited lower occurrence of multiorgan impairment, although some of them affected the cardiovascular and neurological systems more. In patients with lower enzymatic activity, the most frequent involvement was neurological, followed by peripheral vascular disease. (4) Conclusions: FD patients exhibited wide phenotypic variability, even at single-organ level, likely due to the individual genetic mutation, although other factors may contribute. Compared to the conventional management, a multidisciplinary approach, as that prompted at our Center, allows one to achieve early clinical detection and management.
From Parasitized to Healthy-Looking Ants (Hymenoptera: Formicidae): Morphological Reconstruction Using Algorithmic Processing
Authors: Csősz Sándor , Báthori Ferenc , Molet Mathieu , Majoros Gábor , Rádai Zoltán
Published: April 2022

Background: Parasites cause predictable alternative phenotypes of host individuals. Investigating these parasitogenic phenotypes may be essential in cases where parasitism is common or taxa is described based on a parasitized individual. Ignoring them could lead to erroneous conclusions in biodiversity-focused research, taxonomy, evolution, and ecology. However, to date, integrating alternative phenotypes into a set of wild-type individuals in morphometric analysis poses extraordinary challenges to experts. This paper presents an approach for reconstructing the putative healthy morphology of parasitized ants using algorithmic processing. Our concept enables the integration of alternative parasitogenic phenotypes in morphometric analyses. Methods: We tested the applicability of our strategy in a large pool of Cestoda-infected and healthy individuals of three Temnothorax ant species (T. nylanderi, T. sordidulus, and T. unifasciatus). We assessed the stability and convergence of morphological changes caused by parasitism across species. We used an artificial neural network-based multiclass classifier model to predict species based on morphological trait values and the presence of parasite infection. Results: Infection causes predictable morphological changes in each species, although these changes proved to be species-specific. Therefore, integrating alternative parasitogenic phenotypes in morphometric analyses can be achieved at the species level, and a prior species hypothesis is required. Conclusion: Despite the above limitation, the concept is appropriate. Beyond parasitogenic phenotypes, our approach can also integrate morphometric data of an array of alternative phenotypes (subcastes in social insects, alternative morphs in polyphenic species, and alternative sexes in sexually dimorphic species) whose integrability had not been resolved before.
Growth Traits and Sperm Proteomics Analyses of Myostatin Gene-Edited Chinese Yellow Cattle
Authors: Zhao Yuefang , Yang Lei , Su Guanghua , Wei Zhuying , Liu Xuefei , Song Lishuang , Hai Chao , Wu Di , Hao Zhenting , Wu Yunxi , Zhang Li , Bai Chunling , Li Guangpeng
Published: April 2022

Chinese Yellow Cattle, an ancient and domesticated breed for draft service, provide unique animal genetic resources with excellent genetic features, including crude feed tolerance, good stress resistance, strong adaptability, and tender meat quality; however, their production performance and meat yield are significantly inferior. Herein, the myostatin gene (MSTN), a negative regulator of skeletal muscle development, was knocked out by CRISPR/Cas9 technology. Eight MSTN gene-edited bull calves (MT) were born, and six of them are well-developed. Compared with the control cattle (WT), the growth trait indexes of MT cattle were generally increased, and the hindquarters especially were significantly improved. The biochemical indexes and the semen characteristics demonstrated that MT bulls were healthy and fertile. Consistent with our conjecture, the wobble and beating of MT bull spermatozoa were significantly higher than that of WT. Nine sperm motility-related proteins and nineteen mitochondrial-related proteins were identified by up-regulation in MT bull spermatozoa using FLQ proteomic technique and act to govern sperm flagellum assembly, organization, and beating and provide sufficient energy for sperm motility. The current study confirmed that the MSTN gene-edited Chinese Yellow cattle have improved growth traits and normal fertility, which can be used for beef cattle production and breeding.
Influence of Specific Treatment Parameters on Nontarget and Out-of-Field Doses in a Phantom Model of Prostate SBRT with CyberKnife and TrueBeam
Authors: Kruszyna-Mochalska Marta , Skrobala Agnieszka , Romanski Piotr , Ryczkowski Adam , Suchorska Wiktoria , Kulcenty Katarzyna , Piotrowski Igor , Borowicz Dorota , Graczyk Kinga , Matuszak Natalia , Malicki Julian
Published: April 2022

The aim of the study was to determine the influence of a key treatment plan and beam parameters on overall dose distribution and on doses in organs laying in further distance from the target during prostate SBRT. Multiple representative treatment plans (n = 12) for TrueBeam and CyberKnife were prepared and evaluated. Nontarget doses were measured with anionization chamber, in a quasi-humanoid phantom at four sites corresponding to the intestines, right lung, thyroid, and head. The following parameters were modified: radiotherapy technique, presence or not of a flattening filter, degree of modulation, and use or not of jaw tracking function for TrueBeam and beam orientation set-up, optimization techniques, and number of MUs for CyberKnife. After usual optimization doses in intestines (near the target) were 0.73% and 0.76%, in head (farthest from target) 0.05% and 0.19% for TrueBeam and CyberKnife, respectively. For TrueBeam the highest peripheral (head, thyroid, lung) doses occurred for the VMAT with the flattening filter while the lowest for 3DCRT. For CyberKnife the highest doses were for gantry with caudal direction beams blocked (gantry close to OARs) while the lowest was the low modulated VOLO optimization technique. The easiest method to reduce peripheral doses was to combine FFF with jaw tracking and reducing monitor units at TrueBeam and to avoid gantry position close to OARs together with reduction of monitor units at CyberKnife, respectively. The presented strategies allowed to significantly reduce out-of-field and nontarget doses during prostate radiotherapy delivered with TrueBeam and CyberKnife. A different approach was required to reduce peripheral doses because of the difference in dose delivery techniques: non-coplanar using CyberKnife and coplanar using TrueBeam, respectively.
Evaluation of Hemodynamic Changes in Retrobulbar Blood Vessels Using Color Doppler Imaging in Diabetic Patients
Authors: Madhpuriya Gulshan , Gokhale Sudheer , Agrawal Alka , Nigam Prakhar , Wan Yung-Liang
Published: April 2022

Background—Diabetic retinopathy is a common complication of long-standing hyperglycemia. Microangiopathy-induced retinal changes are well-visualized on ophthalmoscopic examination. However, certain hemodynamic alterations have also been documented in the diabetic population, which have not been completely understood. Aim—To study the hemodynamic changes in retrobulbar circulation in diabetic patients with and without retinopathy, and to compare these changes with non-diabetic controls. Materials and Methods—This hospital-based prospective study included 50 diabetic and 50 non-diabetic patients. The diabetic groups consisted of 25 patients without retinopathy and 25 patients with retinopathy, and were labeled as Groups I and II, respectively. All subjects underwent orbital color Doppler ultrasonography using a linear high-frequency probe. The color Doppler parameters (peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistive index (RI)) were measured and recorded using the spectral waveform of the ophthalmic artery (OA), central retinal artery (CRA), and short posterior ciliary arteries (SPCA). Comparison of obtained values was carried out using appropriate tests of significance. Results—The resistive indices of the ophthalmic, central retinal, and short posterior ciliary arteries were significantly higher in diabetic patients compared to controls (p < 0.001). The difference was also significant between Group I and Group II. Comparison of PSV and EDV of CRA and SPCAs among three groups using one-way ANOVA revealed a significant difference, with the highest blood flow velocities in the control group and the lowest in diabetics with retinopathy. The ophthalmic artery showed no significant change in blood flow velocity. Analysis using the Pearson correlation coefficient provided a positive correlation between the RI values of OA, CRA, and SPCA and the presence of diabetic retinopathy (OA = r 0.417, p < 0.001; CRA = r 0.466, p < 0.001; SPCA = r 0.438; p < 0.001). Conclusions—The resistive index of OA, CRA, and SPCA is a reliable indicator to assess diabetic-associated hemodynamic changes. The use of orbital color Doppler ultrasonography in diabetic patients can help in the identification of patients who are at risk of developing retinopathy.
Analysis of the Thermo-Mechanical Behavior of a Multi-Plate Clutch during Transient Operating Conditions Using the FE Method
Authors: Schneider Thomas , Dietsch Maximilian , Voelkel Katharina , Pflaum Hermann , Stahl Karsten
Published: April 2022

Failures of multi-plate clutches must be reliably excluded due to safety-critical functionalities in the drive train. The main reason for failures of multi-plate clutches due to long-term and spontaneous damage is thermal damage. In this paper, a parameterizable two-dimensional finite element model is developed and validated for damage prevention and for analyzing the thermo-mechanical behavior of a clutch in transient operation. Both numerical verification and validation with experimental results are very good despite the simplifications in the model. Subsequently, the temperature and pressure distribution of the individual friction areas is determined. The results show that the maximum temperatures tend to occur at the outer diameter of the friction area. The pressure distribution is very homogeneous. In a parameter study, the influence of Young’s modulus of the friction lining, the thermal conductivity of the friction lining, and the steel plate thickness on the temperature and pressure behavior in the clutch is investigated. Although the Young’s modulus of the friction lining influences the pressure distribution in the friction contact, the temperature behavior is only slightly changed by the variation of the elastic modulus due to the load case. The thermal conductivity of the lining and steel plate thickness have a strong influence on the temperature level in the clutch. However, the distribution of pressures is still very homogeneous compared to the reference model.
Influence of Mechanical, Thermal, Oxidative and Catalytic Processes on Thickener Structure and Thus on the Service Life of Rolling Bearings
Authors: Grebe Markus , Ruland Michael
Published: April 2022

Constant further developments in application technology with the aim of higher economic efficiency and power density place ever greater demands on mechanical components and construction elements and thus on the lubricating greases used. This is particularly true in the area of roller bearings, in which lubricating greases are sometimes used with high mechanical stress and in wide temperature ranges. A current example is the rolling bearings in the assemblies of hybrid vehicles, which are subjected to extreme thermal and mechanical loads due to engine downsizing, high speeds and the radiant heat from the combustion engine. Investigations at the Competence Center of Tribology Mannheim (KTM) show that the grease service life for roller bearing lubrication, even at high temperatures, does not only depend on classic oil aging. In numerous roller bearing tests and by means of rheological measurements, it could be shown that the loss of the lubricating effect is a consequence of the change in the thickener structure. Mechanical, thermal, oxidative and catalytic processes play a decisive role here. In this article, a scientific method is presented for the first time as to how these individual influencing factors can be examined and evaluated independent from one another. For this purpose, the first results of an ongoing DGMK project are presented and evaluated.
Magnetically Recovered Co and Co@Pt Catalysts Prepared by Galvanic Replacement on Aluminum Powder for Hydrolysis of Sodium Borohydride
Authors: Ozerova Anna M. , Skobelkina Anastasia A. , Simagina Valentina I. , Komova Oksana V. , Prosvirin Igor P. , Bulavchenko Olga A. , Lipatnikova Inna L. , Netskina Olga V.
Published: April 2022

Magnetically recovered Co and Co@Pt catalysts for H2 generation during NaBH4 hydrolysis were successfully synthesized by optimizing the conditions of galvanic replacement method. Commercial aluminum particles with an average size of 80 µm were used as a template for the synthesis of hollow shells of metallic cobalt. Prepared Co0 was also subjected to galvanic replacement reaction to deposit a Pt layer. X-ray diffraction analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, and elemental analysis were used to investigate catalysts at each stage of their synthesis and after catalytic tests. It was established that Co0 hollow microshells show a high hydrogen-generation rate of 1560 mL·min−1·gcat−1 at 40 °C, comparable to that of many magnetic cobalt nanocatalysts. The modification of their surface by platinum (up to 19 at% Pt) linearly increases the catalytic activity up to 5.2 times. The catalysts prepared by the galvanic replacement method are highly stable during cycling. Thus, after recycling and washing off the resulting borate layer, the Co@Pt catalyst with a minimum Pt loading (0.2 at%) exhibits an increase in activity of 34% compared to the initial value. The study shows the activation of the catalyst in the reaction medium with the formation of cobalt–boron-containing active phases.
Geopolymer Concrete with Lightweight Artificial Aggregates
Authors: Kalinowska-Wichrowska Katarzyna , Pawluczuk Edyta , Bołtryk Michał , Nietupski Adam
Published: April 2022

This article presents the physical and mechanical properties of geopolymer concrete with lightweight artificial aggregate. A research experiment where the influence of fly ash–slag mix (FA-S), as part of a pozzolanic additive, on the properties of geopolymers was carried out and the most favorable molar concentration of sodium hydroxide solution was determined. The values of three variables of the examined properties of the geopolymer lightweight concrete (GLC) were adopted: X1—the content of the pozzolanic additives with fly ash + flay ash–slag (FA + FA-S) mix: 200, 400 and 600 kg/m3; X2—the total amount of FA-S in the pozzolanic additives: 0, 50 and 100%; X3—the molarity of the activator NaOH: (8, 10 and 12 M). In order to increase the adhesion of the lightweight artificial aggregate to the geopolymer matrix, the impregnation of the NaOH solution was used. Based on the obtained results for the GLC’s compressive strength after 28 days, water absorption, dry and saturated density and thermal conductivity index, it was found that the most favorable parameters were obtained with 400 kg/m3 of pozzolanic additives (with 50% FA-S and 50% FA) and 10 NaOH molarity. Changes in the activator’s concentration from 8 to 10 M improved the compressive strength by 54% (for a pozzolana content of 200 kg/m3) and by 26% (for a pozzolana content of 600 kg/m3). The increase in the content of pozzolanic additives from 200 to 400 kg/m3 resulted in a decrease in water absorption from 23% to 18%. The highest conductivity coefficient, equal to 0.463 W/m·K, was determined, where the largest amount of pozzolanic additives and the least lightweight aggregate were added. The structural tests used scanning electron microscopy analysis, and the beneficial effect of impregnating the artificial aggregate with NaOH solution was proved. It resulted in a compact interfacial transition zone (ITZ) between the lightweight aggregate and the geopolymer matrix because of the chemical composition (e.g., silica amount), the silica content and the alkali presoaking process.
Deflection Estimation Model for Prestressed Concrete Slabs with Plastic Inserts Forming Voids
Authors: Zavalis Mindaugas , Daugevičius Mykolas , Jokūbaitis Aidas , Zavalis Robertas , Valivonis Juozas
Published: April 2022

Developed and patented more than 30 years ago, the system of slabs with plastic inserts has become very popular, and it is used all over the world today due to the significantly reduced cost of building construction. Experimental tests have shown that the behaviour of simple bending voided slab structures with plastic inserts during loading is very similar to that of solid slabs. However, their deflection and crack resistance are both slightly inferior to those of solid slabs. When using pretensioned reinforcement, the deflection and crack resistance of voided slabs exceed the above parameters for solid slabs. However, when using plastic inserts to form inner voids in slabs, their cross-section along the span becomes variable. In determining the stiffness of such slab, a problem arises in estimating the moment-of-inertia when the cross-section is variable. To estimate the influence of the voids formed by the plastic inserts on the deflection of prestressed concrete slabs, bending tests of two life-size reinforced concrete slabs were performed. The bending results obtained during the experiment were compared with the results obtained from the numerical model and analytical calculations.
Development and Experimental Assessment of Friction-Type Shear Connectors for FRP Bridge Girders with Composite Concrete Decks
Authors: Davids William G. , Guzzi Dante , Schanck Andrew P.
Published: April 2022

This paper details the development and experimental assessment of a friction-type connector, designed to transfer shear flow between the top flange of a fiber-reinforced polymer (FRP) tub girder and a composite concrete deck for bridge applications. In contrast with previously used bearing-type connectors, this system relies on a deformed FRP surface to transfer shear via direct interlock with the concrete deck. The connector is materially efficient, simple to fabricate, can be used with lower-grade structural or stainless-steel fasteners, and provides a high degree of interface stiffness. Six compression-shear specimens were tested to assess the connector fatigue resistance and ultimate connection strength. Additionally, two short beam specimens were tested in three-point bending, one of which was subjected to fatigue loading. Based on the compression-shear tests and short beam tests, the connection exhibited strength exceeding that predicted by AASHTO for frictional concrete-concrete connections. The connection strengths were significantly greater than the factored demand required by AASHTO for a typical model FRP bridge girder. The cyclic loading of the connection in both compression-shear and beam bending showed that connection stiffness and strength do not significantly degrade, due to the application of 1 × 106 to 6 × 106 cycles of traffic-induced factored fatigue load.
A Study of Hot Deformation Behavior of T15MN High-Speed Steel during Thermal Compression
Authors: Zhao Bo , Chen Zhipei , Ge Changchun
Published: April 2022

The hot deformation behavior of T15MN high-speed steel during thermal compression was studied by experiment and simulation. Specifically, the hot compression test was carried out on a Gleeble-1500 thermal-mechanical simulator at temperatures from 1273 to1423 K and strain rates from 0.01 to 10 s−1 with the deformation degree of 60%. It was found that all the flow stress curves were characterized by a single peak, indicating the occurrence of dynamic recrystallization (DRX), and flow stress will increase with increasing strain rate and decreasing deformation temperature. Based on the experimental data, the constitutive equations and thermal activation energy were obtained (Qact = 498,520 J/mol). Meanwhile, a cellular automaton model was established via the MATLAB platform to simulate the dynamic recrystallization phenomenon during hot deformation. The simulation results indicate that a good visualization effect of the microstructural evolution is achieved. Both increasing deformation temperature and decreasing strain rate can promote the increase in the average size and volume fraction of recrystallized grains (R-grains). Additionally, the calculated flow stress values fit in well with the experimental ones in general, which indicates that the established CA model has a certain ability to predict the deformation behavior of metal materials at elevated temperatures.
Influence of Sugarcane Bagasse Ash and Silica Fume on the Mechanical and Durability Properties of Concrete
Authors: Farrant William Earl , Babafemi Adewumi John , Kolawole John Temitope , Panda Biranchi
Published: April 2022

Cement production is environmentally unsustainable due to the high anthropogenic carbon emissions produced. Supplementary cementitious materials (SCMs), derived from the by-products of different industries, have been deemed an effective way to reduce carbon emissions. The reduction in carbon emissions is achieved by lowering the clinker factor of cement, through a partial replacement with an SCM. Sugarcane Bagasse Ash (SCBA) is produced as an agricultural waste from the sugarcane industry and has gained a lot of attention for being a feasible and readily available pozzolanic material, underutilised as an SCM. This study evaluates alkali-activated sugarcane bagasse ash’s mechanical and durability performance, at varied contents, in binary blended cement concrete and ternary blended cement concrete containing silica fume (SF). Potassium Hydroxide (KOH), used as the alkali activator, is intended to enhance the reactivity of the ash, with the possibility of a high-volume SCBA content. The mechanical performance was investigated by compressive and split tensile strength tests, and durability performance was investigated using the Oxygen Permeability Index (OPI) test. In addition, a micro-CT porosity test was conducted to assess how the microstructure and porosity of the concrete affect the mechanical and durability performance. The results indicated that using SCBA in a ternary blend with SF can significantly improve the overall performance and create less porous concrete. At 30% SCBA and 10% SF replacement, the performance tests revealed the highest mechanical strength and the lowest permeability, outperforming the control concrete and the binary blended cement concrete containing only SCBA.
The Efficiency of Hybrid Intelligent Models in Predicting Fiber-Reinforced Polymer Concrete Interfacial-Bond Strength
Authors: Barkhordari Mohammad Sadegh , Armaghani Danial Jahed , Sabri Mohanad Muayad Sabri , Ulrikh Dmitrii Vladimirovich , Ahmad Mahmood
Published: April 2022

Fiber-reinforced polymer (FRP) has several benefits, in addition to excellent tensile strength and low self-weight, including corrosion resistance, high durability, and easy construction, making it among the most optimum options for concrete structure restoration. The bond behavior of the FRP-concrete (FRPC) interface, on the other hand, is extremely intricate, making the bond strength challenging to estimate. As a result, a robust modeling framework is necessary. In this paper, data-driven hybrid models are developed by combining state-of-the-art population-based algorithms (bald eagle search (BES), dynamic fitness distance balance-manta ray foraging optimization (dFDB-MRFO), RUNge Kutta optimizer (RUN)) and artificial neural networks (ANN) named “BES-ANN”, “dFDB-MRFO -ANN”, and “RUN-ANN” to estimate the FRPC interfacial-bond strength accurately. The efficacy of these models in predicting bond strength is examined using an extensive database of 969 experimental samples. Compared to the BES-ANN and dFDB-MRFO models, the RUN-ANN model better estimates the interfacial-bond strength. In addition, the SHapley Additive Explanations (SHAP) approach is used to help interpret the best model and examine how the features influence the model’s outcome. Among the studied hybrid models, the RUN-ANN algorithm is the most accurate model with the highest coefficient of determination (R2 = 92%), least mean absolute error (0.078), and least coefficient of variation (18.6%). The RUN-ANN algorithm also outperformed mechanics-based models. Based on SHAP and sensitivity analysis method, the FRP bond length and width contribute more to the final prediction results.
Impact of Atomization Pressure on the Particle Size of Nickel-Based Superalloy Powders by Numerical Simulation
Authors: Qing Yongquan , Guo Kuaikuai , Liu Chen , Qin Youyi , Zhan Yu , Shuo Shang , Wei Yanpeng , Yu Bo , Liu Changsheng
Published: April 2022

Vacuum induction melting gas atomization (VIGA) has evolved as an important production technique of superalloy powders used in additive manufacturing. However, the development of powder preparation techniques is limited because the crushing process of gas-atomized metal melt is difficult to characterize by conventional experimental methods. Herein, we report the application of computational fluid dynamics to simulate the breaking behavior of droplets in the process of preparing nickel-based superalloy powders by VIGA, as well as the results on the effect of gas pressure on the atomization process and powder particle size distribution of metal melt. In the process of primary atomization, the crushing morphology of superalloy melt shows an alternate transformation of umbrella shapes and inverted mushroom cloud shapes, and with the increase in atomization pressure, the disorder of the two-phase flow field increases, which is conducive to sufficient breakage of the melt. Most importantly, in the process of secondary atomization and with the increasing atomization pressure, the particle size distribution becomes narrower, the median particle diameter and average particle size decrease, and the decreasing trend of the particle size increases gradually. The simulation results are compliant with the performed nickel-based superalloy powder preparation tests. This study provides insight into the production and process optimization of superalloy powder prepared by the VIGA method.
Decomposition Characteristics of the TTIP (Tetraisopropyl Orthotitanate) Precursor for Atomic Layer Deposition
Authors: Kim Hayeong , An Jihyeok , Maeng SeonJeong , Shin Jae-Soo , Choi Eunmi , Yun Ju-Young
Published: April 2022

The decomposition of tetraisopropyl orthotitanate (TTIP), a representative precursor used in the atomic layer deposition (ALD) of titanium dioxide (TiO2) film, and the resulting changes in the thin film properties of the TiO2 film were investigated. TTIP was evaluated after exposure to thermal stress in an enclosed container. The vapor pressure results provide reasonable evidence that impurities are generated by the decomposition of TTIP under thermal stress. These impurities led to changes in the thermal properties of TTIP and changes in the growth rate, morphology, and composition of the thin film; in particular, these impurities increased the unstable oxidation states of Ti2+ (TiO) content in the TiO2 film. The changes in the properties of the TiO2 film resulting from the changes in the physical properties of TTIP led to a change in the properties of the device. We proved that the thermal stability of the precursor is a factor that can determine the reliability of the ALD process and the resulting thin film. Additionally, systematic evaluation of the precursor can provide useful information that can improve the development of the precursor and the consistency of the process.
A Review on the Effect of Fabric Reinforcement on Strength Enhancement of Natural Fiber Composites
Authors: Arumugam Soundhar , Kandasamy Jayakrishna , Venkatesan Subramani , Murugan Rajesh , Lakshmi Narayanan Valayapathy , Sultan Mohamed Thariq Hameed , Shahar Farah Syazwani , Shah Ain Umaira Md , Khan Tabrej , Sebaey Tamer Ali
Published: April 2022

The main objective of this study is to examine the impact of reinforcements on the strength of natural fiber composites. Recent advancements in natural fiber composites have minimized the usage of man-made fibers, especially in the field of structural applications such as aircraft stiffeners and rotor blades. However, large variations in the strength and modulus of natural fiber degrade the properties of the composites and lower the safety level of the structures under dynamic load. Without compromising the safety of the composite structure, it is significant to enrich the strength and modulus of natural fiber reinforcement for real-time applications. The strength and durability of natural fiber can be enriched by reinforcing natural fiber. The reinforcement effect on natural fiber in their woven, braided, and knit forms enhances their structural properties. It improves the properties of natural fiber composites related to reinforcement with short and random-orientation fibers. The article also reviews the effect of the hybridization of natural fiber with cellulosic fiber, synthetic fiber, and intra-ply hybridization on its mechanical properties, dynamic mechanical properties, and free vibration characteristics, which are important for predicting the life and performance of natural fiber composites for weight-sensitive applications under dynamic load.
A Dipole with Reflector-Backed Active Metasurface for Linear-to-Circular Polarization Reconfigurability
Authors: van Aardt Ruan , Joubert Johan , Odendaal Johann W.
Published: April 2022

In recent years, significant advances have been made in diversifying the capabilities of communication systems by using reconfigurable antennas. There are many types of reconfigurable antennas—to achieve pattern, frequency, or polarization reconfigurability. These antennas are reconfigured either by the mechanical rotation of surfaces or by enabling or disabling specific sections of the structure using electrical switches. This paper focuses on the concept of a polarization reconfigurable antenna based on an active reflector-backed metasurface. An antenna system based on an active reflector-backed metasurface combined with a planar dipole is designed to achieve reconfigurable polarization. The polarization of the designed antenna can be switched between linear and circular polarization states using positive-intrinsic-negative diodes located in the unit cell elements of the metasurface. The measured results correlate well with the simulated results. The antenna has a physical size of 308 × 162 × 35 mm3 with an impedance bandwidth of 4.5% in the linear state and 7% in the circular state, as well as an axial ratio bandwidth larger than 8.3%.
Effects of Steel Fiber and Specimen Geometric Dimensions on the Mechanical Properties of Ultra-High-Performance Concrete
Authors: Fang Haozhen , Gu Mingen , Zhang Shufeng , Jiang Haibo , Fang Zhuangcheng , Hu Jiaxin
Published: April 2022

Ultra-high-performance concrete (UHPC) is an advanced concrete with superior mechanical strength, ductility and durability properties. However, the influence of steel fiber on its constitutive laws and the specimen geometric dimension effect on its strength had not been paid enough attention. To investigate the effect of steel fibers on the properties of UHPC, specimens with different fiber volume contents and fiber types were tested. Meanwhile, the mechanical properties of UHPC at different ages from 3 days to 28 days were conducted. Moreover, specimens with various geometric dimensions were also prepared to study the effect of specimen geometric dimensions (dog-bone-shaped, prism and cylinder specimens) on the properties of UHPC. The results indicated that elastic modulus, tensile peak stress and the corresponding strain increased as the fiber volume content and curing age increased. Specimens with hooked-end fibers exhibited better tensile performance than those with straight fibers. Furthermore, different geometric dimensions of specimens significantly influenced the tensile properties of UHPC. Based on the experimental results, conversion factors were suggested for the transformation of strength obtained from specimens with different geometric dimensions to reference specimens. In addition, both compressive and tensile constitutive laws were proposed to generate the stress–strain relationship of UHPC.
Comparative Assessment of the Shaping Ability of Reciproc Blue, WaveOne Gold, and ProTaper Gold in Simulated Root Canals
Authors: Orel Laura , Velea-Barta Oana-Alexandra , Sinescu Cosmin , Duma Virgil-Florin , Nica Luminița-Maria , Horhat Razvan Mihai , Chirila Raul Dorin , Tudor Anca , Vulcănescu Dan-Dumitru , Negrutiu Meda Lavinia
Published: April 2022

Maintaining the original trajectory of the root canal is a major challenge in endodontic therapy, especially in narrow and curved root canals. The present study aims to assess the shaping capacity of three endodontic systems made of different nickel–titanium alloys on simulated curved root canals. Thirty-six endodontic resin blocks (Ref. V040245, VDW) divided into three groups, each of twelve blocks (n = 12), were shaped, photographed, and analyzed: Group 1-Protaper Gold (PTG) (Dentsply Maillefer, Ballaigues, Switzerland) F2 25/08; Group 2-Reciproc Blue (RB), RB 25/08 (VDW, Munich, Germany); Group 3-WaveOne Gold (WOG) (Dentsply Maillefer), WOG 25/07. Each block was standardized and photographed before and after shaping in the same position, with the foramen oriented to the left. Post-shaping images were superimposed onto the initial ones. Thirteen measurement points were used for evaluation, spaced with 1 mm distance from one another, from level 0, apical foramen, to level 12, coronal orifice. The amount of removed resin from inner (X1) and outer (X2) walls, the direction of transportation (X1 − X2), and the centering ability (X1 − X2)/Y were measured, calculated, and comparatively analyzed. Statistical differences (p < 0.05) were observed between the shaping capacity of the considered systems in the middle and coronal thirds. PTG had a better centering ability than WOG and RB in the coronal third, while RB was more centered in the middle third in comparison to both WOG and PTG. In the apical third, the centering capacity of WOG was higher, without being statistically significant. WOG 25/07 and PTG 25/08 tend to cut more on the inner wall of the root canals, and RB 25/08 on the external one.
Stereoselective Synthesis and Anticancer Activity of 2,6-Disubstituted trans-3-Methylidenetetrahydropyran-4-ones
Authors: Bartosik Tomasz , Drogosz-Stachowicz Joanna , Janecka Anna , Kędzia Jacek , Pacholczyk-Sienicka Barbara , Szymański Jacek , Gach-Janczak Katarzyna , Janecki Tomasz
Published: April 2022

In this report, we present efficient and stereoselective syntheses of 2,6-disubstituted trans-3-methylidenetetrahydropyran-4-ones and 2-(4-methoxyphenyl)-5-methylidenetetrahydropyran-4-one that significantly broaden the spectrum of the available methylidenetetrahydropyran-4-ones with various substitution patterns. Target compounds were obtained using Horner–Wadsworth–Emmons methodology for the introduction of methylidene group onto the pyranone ring. 3-Diethoxyphosphoryltetrahydropyran-4-ones, which were key intermediates in this synthesis, were prepared by fully or highly stereoselective addition of Gilman or Grignard reagents to 3-diethoxyphosphoryldihydropyran-4-ones. Addition occurred preferentially by axial attack of the Michael donors on the dihydropyranone ring. Relative configurations and conformations of the obtained adducts were assigned using a detailed analysis of the NMR spectra. The obtained methylidenepyran-4-ones were evaluated for cytotoxic activity against two cancer cell lines (HL-60 and MCF-7). 2,6-Disubstituted 3-methylidenetetrahydropyran-4-ones with isopropyl and phenyl substituents in position 2 were more cytotoxic than analogs with n-butyl substituent. Two of the most cytotoxic analogs were then selected for further investigation on the HL-60 cell line. Both analogs induced morphological changes characteristic of apoptosis in cancer cells, significantly inhibited proliferation and induced apoptotic cell death. Both compounds also generated DNA damage, and one of the analogs arrested the cell cycle of HL-60 cells in the G2/M phase. In addition, both analogs were able to inhibit the activity of topoisomerase IIα. Based on these findings, the investigated analogs may be further optimized for the development of new and effective topoisomerase II inhibitors.
Structure Determination, Mechanical Properties, Thermal Stability of Co2MoB4 and Fe2MoB4
Authors: Zhao Shijing , Zhou Wenju , Xiang Xiaojun , Cao Xuyan , Chen Ning , Chen Weifeng , Yu Xiaohui , Yan Bingmin , Gou Huiyang
Published: April 2022

The precise determination of atomic position of materials is critical for understanding the relationship between structure and properties, especially for compounds with light elements of boron and single or multiple transition metals. In this work, the single crystal X-ray diffraction is employed to analyze the atomic positions of Co2MoB4 and Fe2MoB4 with a Ta3B4-type structure, and it is found that the lengths of B-B bonds connecting the two zig-zag boron chains are 1.86 Å and 1.87 Å, but previously unreported 1.4 Å. Co and Fe atoms occupy the same crystallographic position in lattice for the doped samples and the valence is close to the metal itself, and Co/Fe K-edge X-ray Absorption Fine Structure(XAFS) spectra of borides with different ratios of Co to Fe are collected to detect the local environment and chemical valence of Co and Fe. Vickers hardness and nano indentation measurements are performed, together with the Density Functional Theory (DFT) calculations. Finally, Co2MoB4 possess better thermal stability than Fe2MoB4 evaluated by Thermogravimetric Differential Thermal Analysis (TG-DTA) results.
Viscoelastic Properties of Fully Biomass-Based Transparent Plastic Comprising Cellulose Acetate and Citrate Ester
Authors: Kimura Takeyoshi , Kida Takumitsu , Yamaguchi Masayuki
Published: April 2022

Viscoelastic properties including melt processability were evaluated for a fully biomass-based glassy plastic comprising cellulose acetate (CA) and triethyl citrate (TEC). The TEC exerted an excellent plasticizing effect without dissolving the CA crystals. Pure CA has poor melt processability. In contrast, the TEC-plasticized CA had good melt-processability at 205 °C, which is lower than the degradation temperature of CA. Extrusion was possible even at 1000 s−1 without any flow instabilities, similar to conventional plastics showing good processability at extrusion. Furthermore, there was marked strain-hardening behavior in the transient elongational viscosity, suggesting that various processing operations are possible, such as a long-chain branched polymer. This biomass-based plastic can be used as a substitute for conventional glassy plastics because it is highly transparent and its softening temperature is above 100 °C.