bluuebunny/crossref_metadata_2025 huggingface dataset:
Host Range and Loop-Mediated Isothermal Amplification Detection of Globisporangium sylvaticum from Guizhou, China
Authors: Zhang Jing , Sun Xiaonan , Ao Ningjing , Zou Huayan , Shao Huijuan , Kageyama Koji , Feng Wenzhuo
Published: July 2023

Globisporangium, especially G. sylvaticum, causes devastating root rot, blight, and other diseases in various species of cash crops. To investigate the distribution and host range of G. sylvaticum in Guizhou, a suitable habitat for this pathogen, we collected 156 root-diseased samples, isolated the pathogens, and found that G. sylvaticum is widespread and has eleven host plants, including four novel hosts. Furthermore, to effectively identify G. sylvaticum, we developed a simple and dependable method based on loop-mediated isothermal amplification (LAMP), which used a primer set designed from the internal transcribed spacer sequences with high specificity and sensitivity of 1 pg/μL. Additionally, to perform field identification, we used the “Plant-LAMP” method with crude DNA extraction to detect the pathogen in 45 root samples from nine species of plants. Our results showed that this method could effectively detect G. sylvaticum in diseased roots. Therefore, our findings not only enrich existing research on the diversity of pathogenic Globisporangium in Guizhou but also present an efficient LAMP field detection method that could significantly contribute to plant disease management and prevention.
Orthogeriatric Assessment of the Elderly Patient with Fragility Hip Fracture: Preliminary Results of a Prospective Study
Authors: Salis Francesco , Puxeddu Benedetta , Piras Veronica , Belfiori Maristella , Marongiu Giuseppe , Capone Antonio , Mandas Antonella
Published: July 2023

Nowadays, more studies deal with “OrthoGeriatrics”, for the co-management of elderly patients suffering fractures, from the admission to the discharge and beyond. For the first time at Cagliari University Hospital, we introduced an orthogeriatric service, in which trained geriatricians stay in orthopedic unit alongside trained orthopedics. The primary aim of the study was to analyze the rate of death and rehospitalization in elderly femur-fractured people of 65 or more years of age, identifying possible predictive factors. The secondary aim of the study was to analyze the recovery of daily living autonomies during the months following surgery. To reach the aim, we designed a prospective study, which is currently ongoing. We evaluated femur-fractured patients aged 65 years or more with a comprehensive geriatric assessment before surgery. The most common fractures were lateral hip ones, treated with osteosynthesis. Cognitive–affective, functional, and nutritional status, mood, and comorbidities were less impaired than in the outpatient service of the same hospital devoted to frail elderly. Pain control was excellent. A significantly low delirium incidence was found. More than a third of the sample were recognized as frail (according to the Survey of Health, Ageing and Retirement in Europe—Frailty Instrument (SHARE-FI)), and over a third of the sample were identified as a moderate-high risk of hospitalization and death (according to Multidimensional Prognostic Index (MPI)). Overall mortality rate was 13.87%, and rehospitalization rate was 11.84%. Frail people were more likely to die than non-frail (HR: 5.64), and pre-frail ones (HR: 3.97); similarly, high-risk patients were more likely to die than low-risk (HR: 8.04), and moderate-risk ones (HR: 5.46). Conversely, neither SHARE-FI nor MPI predicted rehospitalization. Creatinine (OR: 2.66, p = 0.003) and folate (OR: 0.75, p = 0.03) levels were independently associated with death and rehospitalization, respectively. Finally, the patients did recover the lost autonomies later, 6 months after surgery. Our study demonstrated that SHARE-FI and MPI are reliable tools to predict mortality in an orthogeriatric setting, and that creatinine and folate levels should also be measured given their independent association with negative outcomes.
Assisted Reproductive Technology and Breech Delivery: A Nationwide Cohort Study in Singleton Pregnancies
Authors: Londero Ambrogio , Massarotti Claudia , Xholli Anjeza , Fruscalzo Arrigo , Cagnacci Angelo
Published: July 2023

Since essential factors have changed in recent years in assisted reproduction technologies (ARTs), this study reassessed the association between ART and breech presentation. We primarily aimed to estimate the correlation between ART and breech at delivery. Secondary purposes were to evaluate the correlation between other subfertility treatments (OSTs) and breech and to assess possible confounding factors and temporal trends. This study investigated the 31,692,729 live birth certificates from US states and territories in the 2009–2020 period. The inclusion criteria were singleton births reporting the method of conception and the presentation at delivery. The outcome was the breech presentation at delivery, while the primary exposure was ART, the secondary exposure was OST, and the potential confounding factors from the literature were considered. ART (OR 2.32 CI.95 2.23–2.41) and OST (OR 1.79 CI.95 1.71–1.87) were independent and significant risk factors for breech at delivery (p < 0.001). This study confirmed breech presentation risk factors maternal age, nulliparity, tobacco smoke, a previous cesarean delivery (CD), neonatal female sex, gestational age, and birth weight. Black race and Hispanic origin were verified to be protective factors. We found breech prevalence among ART and OST to be stable during the study period. Meanwhile, newborn birth weight was increased, and the gap between breech and other presentations in ART was reduced. Our results indicate that singleton pregnancies conceived by ART or OST were associated with a higher risk of breech at delivery. Well-known risk factors for the breech presentation were also confirmed. Some of these factors can be modified by implementing interventions to reduce their prevalence (e.g., tobacco smoke and previous CD).
Composition and Diversity of Soil Microbial Communities in Walnut Orchards at Different Altitudes in Southeastern Tibet
Authors: Yan Ruyu , Zhao Ximei , Li Penghui , Si Zhuanyun , Gao Yang , Li Jifu
Published: July 2023

To understand the distribution of the soil microbial community in natural walnut orchards at different altitude gradients (3000–3500 m) and to reveal the mechanism of the soil microbial activity in natural walnut orchards adapting to high-altitude environments, soil samples from four groups of natural walnut orchards in Gyaca County, southeast Tibet, were studied. Illumina MiSeq sequencing technology was used to analyze the community composition and diversity of soil bacteria and fungi and their responses to the altitudes. The alpha diversity results showed that the vertical distribution pattern of the fungal community was more obvious than that of the bacterial community and the bacterial community diversity first increased (~3364 m) and then decreased with altitude. The number of amplicon sequence variants (ASVs) in the soil bacterial community was significantly higher than that in the fungal community, but soil bacterial and fungal communities in walnut orchards at different altitudes exhibited both inheritance and uniqueness. At the phylum level, the dominant bacterial phyla at different altitudes were Actinobacteria, Acidobacteria, Proteobacteria, and Chloroflexi (relative abundances > 10.0% in each treatment). With the increase in altitude, the relative abundance of Actinobacteria increased gradually while that of Acidobacteria and Proteobacteria decreased gradually. The dominant fungal phyla were Ascomycota, Basidiomycota, and Mortierellomycota (relative abundances >5.0% in each treatment). With the increase in altitude, the relative abundance of Ascomycota increased significantly. At the genus level, the number of dominant bacteria and fungi in the soil decreased gradually with increased altitude and showed anisotropic distribution characteristics. The relative abundances of Actinobacteria among the bacterial phyla—and Olpidiomycota and Zoopagomycota among the fungal phyla—were positively correlated with the altitude (p < 0.05). Most dominant bacterial and fungal phyla were highly significantly (p < 0.01) or significantly (p < 0.05) negatively correlated with the altitude. Soil nitrogen and phosphorus availabilities are the main limiting factors of microbial community diversity. Therefore, altitude caused changes in soil physicochemical properties which directly or indirectly affected the composition and diversity of soil bacterial and fungal communities, and our study provides a theoretical basis for the altitudinal pattern and succession changes in soil microbial communities in the natural walnut orchards of southeast Tibet.
Right Ventricular Myocardial Involvement in Anderson–Fabry Disease at Diagnosis: Evaluation with Three-Dimensional Strain Imaging
Authors: Pucci Martina , Iadevaia Velia , Gammaldi Vittoria , Iervolino Adelaide , Capece Luca Maria , Sciascia Domenico , Cuomo Vittoria , Iacono Marina , Paoletta Daniele , Santoro Ciro , Esposito Roberta
Published: July 2023

Background: Right ventricular (RV) involvement in Anderson–Fabry disease (AFD) is well known in the advanced stages of the disease RV hypertrophies, but little is known about the early involvement. The aim of our study was to assess RV function in AFD patients at diagnosis. Methods: A total of 23 AFD patients and 15 controls comparable for age and sex were recruited. A complete 2D standard echo with 3D volumetric and strain analysis of RV was performed. Results: Two patient populations, comparable for clinical baseline characteristics were considered. RV free wall thickness was significantly increased in the AFD group. No significant differences in standard RV indices (TAPSE, transverse diameter, tissue Doppler velocities of the lateral tricuspid annulus) were found. A 3D volumetric analysis showed reduced RV ejection fraction and lower values of longitudinal septal, free wall and global longitudinal strain (GLS) in AFD patients. RV free wall thickness significantly correlated with both free wall RV LS and RV GLS. In multiple linear regression analysis, RV free wall thickness was independently associated with RV GLS even after correction for age and heart rate. Conclusions: In AFD patients, 3D echocardiography allows for the identification of early subclinical functional impairment of RV. RV dysfunction is independently associated with RV hypertrophy.
The Association of Body Mass Index with COVID-19 Complications and Survival Rate at a Tertiary Hospital
Authors: AlBahrani Salma , Al-Maqati Thekra N. , Al Naam Yaser A. , Alqahtani Jaber S. , Alqahtani Abdullah S. , AlRabeeah Saad , Aldhahir Abdulelah M. , Alkhalaf Faisal , Alzuraiq Hind R. , Alenezi Maryam Hamad , Alzahrani Amal , Bakkar Mohanad , Albahrani Zainab , Maawadh Rawan M.
Published: July 2023

A high body mass index (BMI) is a known risk factor for coronavirus infection in hospitalized patients. Our study examined the association between BMI and complications and the survival rate among COVID-19 patients. This retrospective analysis used data from a tertiary hospital in the Eastern Region of Saudi Arabia during two waves of the COVID-19 pandemic. The study included 600 participants, with the majority being between 41 and 60 years old (41.3%) and men comprising 63.5% of the sample. Approximately 42.5% of patients were obese, and 31.3% were overweight. The results showed that BMI was significantly linked to respiratory diseases (p = 0.013); end-stage renal disease (p = 0.021); and cardiovascular disease (p = 0.003) but not diabetes mellitus (p = 0.064). Death occurred in 10.8% of patients; 33.8% were admitted to the ICU; 13.8% needed mechanical ventilation; and 60.7% had lung infiltration. Obese patients with oxygen saturation levels below 93% were 2.45 times more likely to require mechanical ventilation than those in the normal-weight group. Overweight and obese patients were also more likely to require mechanical ventilation than normal-weight patients, with odds ratios of 3.66 and 2.81, respectively. The BMI categorized was not associated with survival rate in COVID-19-hospitalized patients using Kaplan-Meier survival plots (p = 0.061). However, the BMI categorized was associated with survival rate in COVID-19 ICU patients (p < 0.001). In addition, the overweight showed a statistically significant higher hazard ratio of 2.22 (p = 0.01) compared to normal-weight patients using a Cox regression model. A high BMI was identified as an independent risk factor for reduced oxygen saturation (<93%), the need for mechanical ventilation, lung infiltration, mortality, and longer ICU stays in COVID-19 patients.
Strength and Microstructure Assessment of Partially Replaced Ordinary Portland Cement and Calcium Sulfoaluminate Cement with Pozzolans and Spent Coffee Grounds
Authors: Pushpan Soorya , Ziga-Carbarín Javier , Rodríguez-Barboza Loth I. , Sanal K. C. , Acevedo-Dávila Jorge L. , Balonis Magdalena , Gómez-Zamorano Lauren Y.
Published: July 2023

Supplementary cementitious materials are considered a viable and affordable way to reduce CO2 emissions from the cement industry’s perspective since they can partially or nearly entirely replace ordinary Portland cement (OPC). This study compared the impact of adding spent coffee grounds (SCGs), fly ash (FA), and volcanic ash (VA) to two types of cement: OPC and calcium sulfoaluminate cement (CSA). Cement samples were characterized using compressive strength measurements (up to 210 days of curing), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), attenuated total reflection infrared spectroscopy, and hydration temperature measurements. In all the studied systems, the presence of SCGs reduced compressive strength and delayed the hydration process. CSA composite cement containing 3.5% SCGs, 30% FA, and 30% VA showed compressive strength values of 20.4 MPa and 20.3 MPa, respectively, meeting the minimum requirement for non-structural applications. Additionally, the results indicate a formation of cementitious gel, calcium silicate hydrate (C-S-H) in the OPC-based composite cements, and calcium alumino-silicate hydrate (C-A-S-H) as well as ettringite in the CSA-based composite cements.
Design and Synthesis of NTU-9/C3N4 Photocatalysts: Effects of NTU-9 Content and Composite Preparation Method
Authors: Makowski Damian , Lisowski Wojciech , Baluk Mateusz A. , Klimczuk Tomasz , Bajorowicz Beata
Published: July 2023

Hybrid materials based on graphitic carbon nitride (g-C3N4) and NTU-9 metal–organic frameworks (MOF) were designed and prepared via solvothermal synthesis and calcination in air. The as-prepared photocatalysts were subsequently characterized using Brunauer–Emmett–Teller (BET) analysis, UV-Vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL) emission spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The obtained NTU-9/C3N4 composites showed a greatly improved photocatalytic performance for the degradation of toluene in the gas phase under LED visible-light irradiation (λmax = 415 nm). The physicochemical properties and photocatalytic activities of the obtained NTU-9/C3N4 materials were tuned by varying the NTU-9 content (5–15 wt%) and preparation method of the composite materials. For composites prepared by calcination, the photocatalytic activity increased with decreasing NTU-9 content as a result of the formation of TiO2 from the MOFs. The best photocatalytic performance (65% of toluene was photodegraded after 60 min) was achieved by the NTU-9/C3N4 sample prepared via the solvothermal method and containing 15 wt% MOF, which can be attributed to the appropriate amount and stable combination of composite components, efficient charge separation, and enhanced visible-light absorption ability. The photocatalytic mechanisms of the prepared hybrid materials depending on the preparation method are also discussed.
Effect of Aluminosilicates’ Particle Size Distribution on the Microstructural and Mechanical Properties of Metakaolinite-Based Geopolymers
Authors: Kohout Jan , Koutník Petr , Hájková Pavlína , Kohoutová Eliška , Soukup Aleš , Vakili Mohammadtaghi
Published: July 2023

The present study focused on investigating the differences in properties between calcined and milled aluminosilicates with different particle size distributions. Two types of clay, i.e., kaolin and kaolinitic claystone, were subjected to calcination at 750 °C, and subsequent milling to obtain different fractions with distinct particle size distributions. These fractions were then combined with a potassium alkaline activator and quartz sand in a 50:50 weight ratio to form a geopolymer composite. The geopolymer binders were then characterized using a mercury intrusion porosimeter (MIP), scanning electron microscopy (SEM), and a rotary rheometer. Mechanical tests were conducted on the geopolymer composites prepared from aluminosilicates with varying particle size distributions. The findings indicated that aluminosilicates with a finer particle size distribution exhibited higher levels of dissolved aluminum (10,000 mg/kg) compared to samples with coarser particle size distributions (1000 mg/kg). Additionally, as the particle size distribution decreased, the dynamic viscosity of the geopolymer binders increased, while the average pore size decreased. Finally, the mechanical properties of the geopolymer composites derived from both tested aluminosilicates demonstrated a decline in performance as the mean particle size increased beyond 10 µm.
Evaluation of Photocatalytic, Antioxidant, and Antibacterial Efficacy of Almond Oil Capped Zinc Oxide Nanoparticles
Authors: Ramzan Iqra , Bashir Mahwish , Saeed Adnan , Khan Babar Shahzad , Shaik Mohammed Rafi , Khan Merajuddin , Shaik Baji , Khan Mujeeb
Published: July 2023

In this study, ZnO nanoparticles (NPs) were synthesized in the presence of almond oil at various molar ratios of zinc acetate and sodium hydroxide, including 0.5:1, 0.75:1, 1:1, 1.25:1, and 1.5:1, to obtain pH values of 11, 10, 9, 8, and 7, respectively. The XRD results revealed that ZnO NPs exhibit a hexagonal structure, with high crystallinity. SEM results showed that dense and large sized ZnO NPs were formed at pH 11, and relatively small (~30–40 nm) NPs were obtained at pH 9. The size distribution can be explained in terms of the presence of OH− ions at different pH levels. However, the larger size of the NPs at pH 7 compared to those at pH 8–11 were due to the coalescence of NPs suitable for antioxidant/antibacterial activities. ZnO NPs demonstrated a high degradation efficiency (~93%) in 90 min, with a high rate constant for Methyl Orange (MO), which is better than the previously reported rate. The larger sized almond oil capped ZnO NPs also showed excellent radical scavenging activity (94%) and are proven to be good carriers to resist Escherichia coli (E. coli) bacteria.
Effect of Initial Orientation on the Anisotropy in Microstructure and Mechanical Properties of 2195 Al–Li Alloy Sheet during Hot Tensile Deformation
Authors: Ning Jian , Liang Jiangkai , Hu Xinyu , Ruan Xianggang , He Zhubin
Published: July 2023

The 2195 Al–Li alloy, as one of the representative third-generation Al–Li alloys, has extensive applications in lightweight aerospace structures. In this paper, the anisotropy in mechanical properties and microstructure evolution of 2195 Al–Li alloy sheets were investigated under a strain rate of 0.01, 0.1, 1 s−1 and a temperature of 440 and 500 °C. Experimental results showed that the hot tensile properties of the 2195 Al–Li alloy sheet exhibited a strong dependence on loading directions. The peak stress (PS) and elongation (EL) along the rolling direction (RD) were larger than the transverse direction (TD). For the tests carried out at 440 °C-1 s−1, the PS values of the sheets stretched along the RD and TD are 142.9 MPa and 110.2 MPa, respectively. And, most of the PS anisotropy values are larger than 15%. The anisotropy in EL is less significant than in PS. All the differences are about 10%. Moreover, dimples in the samples stretched along RD were more and deeper than those along TD at 440 °C. The fracture morphology along RD and TD were similar, and both were cleavage fractures at 500 °C. Particularly, the fractions of high angle grain boundaries (HAGBs) along TD were all about 5% larger than those of RD. And, there were more small-sized continuous dynamic recrystallization (CDRX) grains inside the initial grains and discontinuous dynamic recrystallization (DDRX) grains featured with the local bulge of grain boundaries along TD. This was due to the smaller average Schmid factor and the vertical EL trend of the initial grains when the samples were stretched along TD. A model of grain evolution during the dynamic recrystallization (DRX) along RD and TD was proposed based on EBSD results. The Schmid factor and banded structure had a more prominent effect on the hot ductility of the 2195 Al–Li alloy compared with the degree of DRX, thus presenting a higher EL and better hot ductility along RD.
Material Data Identification in an Induction Hardening Test Rig with Physics-Informed Neural Networks
Authors: Asadzadeh Mohammad Zhian , Roppert Klaus , Raninger Peter
Published: July 2023

Physics-Informed neural networks (PINNs) have demonstrated remarkable performance in solving partial differential equations (PDEs) by incorporating the governing PDEs into the network’s loss function during optimization. PINNs have been successfully applied to diverse inverse and forward problems. This study investigates the feasibility of using PINNs for material data identification in an induction hardening test rig. By utilizing temperature sensor data and imposing the heat equation with initial and boundary conditions, thermo-physical material properties, such as specific heat, thermal conductivity, and the heat convection coefficient, were estimated. To validate the effectiveness of the PINNs in material data estimation, benchmark data generated by a finite element model (FEM) of an air-cooled cylindrical sample were used. The accurate identification of the material data using only a limited number of virtual temperature sensor data points was demonstrated. The influence of the sensor positions and measurement noise on the uncertainty of the estimated parameters was examined. The study confirms the robustness and accuracy of this approach in the presence of measurement noise, albeit with lower efficiency, thereby requiring more time to converge. Lastly, the applicability of the presented approach to real measurement data obtained from an air-cooled cylindrical sample heated in an induction heating test rig was discussed. This research contributes to the accurate offline estimation of material data and has implications for optimizing induction heat treatments.
Effect of Supercritical Bending on the Mechanical & Tribological Properties of Inconel 625 Welded Using the Cold Metal Transfer Method on a 16Mo3 Steel Pipe
Authors: Krbata Michal , Ciger Robert , Kohutiar Marcel , Sozańska Maria , Eckert Maroš , Barenyi Igor , Kianicova Marta , Jus Milan , Beronská Naďa , Mendala Bogusław , Slaný Martin
Published: July 2023

The presented work deals with the investigation of mechanical tribological properties on Inconel 625 superalloy, which is welded on a 16Mo3 steel pipe. The wall thickness of the basic steel pipe was 7 mm, while the average thickness of the welded layer was 3.5 mm. The coating was made by the cold metal transfer (CMT) method. A supercritical bending of 180° was performed on the material welded in this way while cold. The mechanical properties evaluated were hardness, wear resistance, coefficient of friction (COF) and change in surface roughness for both materials. The UMT Tribolab laboratory equipment was used to measure COF and wear resistance by the Ball-on-flat method, which used a G40 steel pressure ball. The entire process took place at an elevated temperature of 500 °C. The measured results show that the materials after bending are reinforced by plastic deformation, which leads to an increase in hardness and also resistance to wear. Superalloy Inconel 625 shows approximately seven times higher rate of wear compared to steel 16Mo3 due to the creation of local oxidation areas that support the formation of abrasive wear and do not create a solid lubricant, as in the case of steel 16Mo3. Strain hardening leads to a reduction of possible wear on Inconel 625 superalloy as well as on 16Mo3 steel. In the case of the friction process, the places of supercritical bending of the structure showed the greatest resistance to wear compared to the non-deformed structure.
Crystallization of Cristobalite in Sodium Borosilicate Glass in the Presence of Cr2O3
Authors: Konon Marina , Polyakova Irina G. , Mazur Anton S. , Saratovskii Artem S. , Danilovich Dmitry P. , Alikin Mikhail
Published: July 2023

Glass containing chromium is a promising material for use in various modern fields of application (laser technology, optoelectronic devices, and luminescent resources). Chromium oxides are well-known nucleating agents that can cause crystallization. One of the most commonly observed crystalline phases in silicate glasses is cristobalite, which lowers their mechanical strength, leading to the destruction of the material. The objective of this investigation was to study in detail the crystallization of cristobalite in sodium borosilicate glass in the presence of 2 mol% Cr2O3, depending on the thermal history of the glass. The glass was studied using XRD, SEM, EPR, FTIR-spectroscopy, XPS, and solid-state NMR. Eskolaite, α-Cr2O3, which had crystallized in this glass, stimulated the bulk crystallization of cristobalite at 550 °C after isothermally treating it for 72 h, due to the phase-separated structure of the glass with its interpenetrating phase morphology. Polytypism, resulting in the incorporation of alkalis into the cristobalite structure, was observed. Cr2O3 causes the catalytic crystallization of cristobalite at an extremely low temperature, which is at lower concentrations and temperatures than in glass containing Fe2O3 with a similar composition. The crystal growth rate and the incubation time for the crystallization of cristobalite were roughly estimated.
Preparation and Characterization for the Thermal Stability and Mechanical Property of PLA and PLA/CF Samples Built by FFF Approach
Authors: Cao Mengyu , Cui Tianqi , Yue Yuhang , Li Chaoyu , Guo Xue , Jia Xin , Wang Baojin
Published: July 2023

Currently, the mechanical performances of polylactic acid (PLA) samples prepared using the fused filament fabrication (FFF) technique are relatively poor. Hence, the carbon fiber (CF) is used to improve the thermal stability and mechanical property of FFF-ed PLA samples in this paper. The crystalline structure, thermal stability, melt flow rate, tensile strength and fractured surface morphology of PLA and PLA/CF samples were investigated with an X-ray diffraction device, differential scanning calorimeter, thermogravimetric analyzer, melt flow rate equipment, universal tensile test machine and scanning electron microscope, respectively. Meanwhile, the reinforcement mechanism of CF on the mechanical property of PLA samples was also analyzed. XRD results revealed that the diffraction peaks intensities of PLA/CF sample were obviously lower than those of PLA sample. TGA and DSC curves illustrated that the initial thermal decomposition temperature, thermal stability and crystallinity of the PLA/CF sample improved significantly. The tensile strength of the PLA/CF sample was 91.58 MPa, which was 42.49% higher than that of the PLA sample. Moreover, SEM images showed that the fractured behavior of the PLA sample varied from brittle fracture to ductile fracture after the introduction of CF. The results concluded the CF is a feasible fiber for enhancing the performances of the PLA sample.
Interaction of Nitrite Ions with Hydrated Portlandite Surfaces: Atomistic Computer Simulation Study
Authors: Tararushkin Evgeny V. , Pisarev Vasily V. , Kalinichev Andrey G.
Published: July 2023

The nitrite admixtures in cement and concrete are used as corrosion inhibitors for steel reinforcement and also as anti-freezing agents. The characterization of the protective properties should account for the decrease in the concentration of free NO2− ions in the pores of cement concretes due to their adsorption. Here we applied the classical molecular dynamics computer simulation approach to quantitatively study the molecular scale mechanisms of nitrite adsorption from NaNO2 aqueous solution on a portlandite surface. We used a new parameterization to model the hydrated NO2− ions in combination with the recently upgraded ClayFF force field (ClayFF-MOH) for the structure of portlandite. The new NO2− parameterization makes it possible to reproduce the properties of hydrated NO2− ions in good agreement with experimental data. In addition, the ClayFF-MOH model improves the description of the portlandite structure by explicitly taking into account the bending of Ca-O-H angles in the crystal and on its surface. The simulations showed that despite the formation of a well-structured water layer on the portlandite (001) crystal surface, NO2− ions can be strongly adsorbed. The nitrite adsorption is primarily due to the formation of hydrogen bonds between the structural hydroxyls on the portlandite surface and both the nitrogen and oxygen atoms of the NO2− ions. Due to that, the ions do not form surface adsorption complexes with a single well-defined structure but can assume various local coordinations. However, in all cases, the adsorbed ions did not show significant surface diffusional mobility. Moreover, we demonstrated that the nitrite ions can be adsorbed both near the previously-adsorbed hydrated Na+ ions as surface ion pairs, but also separately from the cations.
Key Role of Corncob Based-Hydrochar (HC) in the Enhancement of Visible Light Photocatalytic Degradation of 2,4-Dichlorophenoxyacetic Acid Using a Derivative of ZnBi-Layered Double Hydroxides
Authors: Tuong Vy Ngo Thi , Nha Khanh Dang Nguyen , Nghia Nguyen Ngoc , Khoa Le Hai , Nhi Pham Tuan , Hung Le Xuan , Minh Phuong Doan Thi , Kim Phuong Nguyen Thi
Published: July 2023

A superior heterojunction of HC-ZnBi-LDO was synthesized in two steps, namely hydrothermal carbonization, followed by co-precipitation. The 2% HC-ZnBi-LDO heterojunction photocatalysts could degrade over 90.8% of 30 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D) using 1.0 g/L of the catalyst after 135 min of visible light exposure at pH 4. The activity of 2% HC-ZnO-LDO was remarkably stable. Approximately 86.4–90.8% of 30 mg/L 2,4-D was degraded, and more than 79–86.4% of TOC was mineralized by 2% HC-ZnBi-LDO at pH 4 after 135 min of visible light exposure during four consecutive cycles. The rapid separation and migration of charge carriers at the interfaces between HC and ZnBi-LDO were achieved within 2% HC-ZnBi-LDO. Moreover, the electron acceptor characteristic of HC in 2% HC-ZnBi-LDO caused the recombination of charge carriers to decrease significantly, thus generating more reactive radicals, such as hydroxyl radicals (OH●) and superoxide radicals (O2●−). These results demonstrate that the novel 2% HC-ZnBi-LDO is a superior photocatalyst for the remediation of hazardous organic pollutants.
An Innovative Absorption Propagation System Hollow Block Made of Concrete Modified with Styrene–Butadiene Rubber and Polyethylene Terephthalate Flakes to Reduce the Propagation of Mechanical Vibrations in Walls
Authors: Major Maciej , Adamczyk Izabela , Kalinowski Jarosław
Published: July 2023

This paper discusses an innovative APS hollow block wall with a frame made of concrete modified with recycled materials. The technical data of the hollow block, the percentages of the recycled materials, including SBR rubber granules and PET flakes in the modified concrete, and the composition of the concrete modified with this mixture of recycled additives, are presented. To demonstrate the effectiveness of the solution in reducing mechanical vibrations, the effect of the interaction of different frequencies of the mechanical wave on reducing these vibrations was evaluated for APS blocks and Alpha comparison blocks. The test was carried out on a developed test stand dedicated to dynamic measurements for sixteen frequencies in the range from 8 to 5000 Hz, forcing a sinusoidal course of vibrations. The results are presented graphically and show that the new type of APS hollow block wall was much more effective in reducing mechanical vibrations. This efficiency was in the range from 10 to 51% for 12 out of the tested 16 frequencies. For the frequencies of 8, 16, 128, and 2000 Hz, the values were obtained with a difference of 3.58% in favor of the APS hollow block. In addition, the study of the damping effectiveness of the APS hollow blocks, in relation to the vibrations generated by an M-400 impact mill, showed that the APS block wall had a higher damping efficiency of 16.87% compared to the Alpha hollow block for the signal reading on the floor next to the mill, and 18.68% for the signal reading on the mill body. The modified concrete used in the production of the APS hollow blocks enabled the effective use of two recycled materials, SBR rubber and polyethylene terephthalate, in the form of PET flakes.
Effects of Plasma Treatment on the Surface and Photocatalytic Properties of Nanostructured SnO2–SiO2 Films
Authors: Pronin Igor A. , Sigaev Alexander P. , Komolov Alexei S. , Zhizhin Evgeny V. , Karmanov Andrey A. , Yakushova Nadezhda D. , Kyashkin Vladimir M. , Nishchev Konstantin N. , Sysoev Victor V. , Goel Sanket , Amreen Khairunnisa , K Ramya , Korotcenkov Ghenadii
Published: July 2023

In this work, we study the effects of treating nanostructured SnO2–SiO2 films derived by a sol-gel method with nitrogen and oxygen plasma. The structural and chemical properties of the films are closely investigated. To quantify surface site activity in the films following treatment, we employed a photocatalytic UV degradation test with brilliant green. Using X-ray photoelectron spectroscopy, it was found that treatment with oxygen plasma led to a high deviation in the stoichiometry of the SnO2 surface and even the appearance of a tin monoxide phase. These samples also exhibited a maximum photocatalytic activity. In contrast, treatment with nitrogen plasma did not lead to any noticeable changes in the material. However, increasing the power of the plasma source from 250 W to 500 W led to the appearance of an SnO fraction on the surface and a reduction in the photocatalytic activity. In general, all the types of plasma treatment tested led to amorphization in the SnO2–SiO2 samples.
Numerical Analysis of the Impact Resistance of Composite A-Shaped Sandwich Structures
Authors: Gu Xuetao , Li Jiawen , Huang Ji , Ao Yaoliang , Zhao Bingxiong
Published: July 2023

This paper focuses on the finite element analysis simulation of the impact properties of composite sandwich structures made of carbon fiber-reinforced polymer lamina. In the existing studies, the composite sandwich structures with A-shaped cores have superior mechanical properties under quasi-static plane compression loads compared to W-shaped, Y-shaped, and X-shaped cores. However, there is limited research on the impact resistance of this structure. This paper studied the resistance of a composite A-shaped core structure to ballistic impact. Using ABAQUS/explicit finite element analysis software, ballistic impact tests for the composite A-shaped core structure were simulated based on the Hashin and Yeh failure criteria with a progressive damage model introduced in the user-defined subroutine VUMAT. First, the composite Y-shaped core sandwich structure was verified via experiments and simulations to determine the accuracy of the method, and then the composite A-shaped sandwich structure was subjected to a series of ballistic impact simulations. With varied impact velocity, the damage to the front and rear face sheet and cores via ballistic loads was simulated to illustrate the overall dynamic response process of the sandwich structure. Subsequently, a curve was fitted using a ballistic limit velocity equation, which was used as the criterion to evaluate the impact resistance of the composite A-shaped core structure. The results showed that, under the same relative density and the same number of component layers, the ballistic limit velocity of the composite A-shaped core sandwich structure was bigger than the composite Y-shaped core sandwich structure. The composite A-shaped core structure had 12.23% higher ballistic limit velocity than the composite Y-shaped core, indicating the impact resistance capabilities of the A-shaped core structure. In addition, the impact location’s effect on the impact response was investigated.
Grain Size-Dependent Thermal Expansion of Nanocrystalline Metals
Authors: Olsson Pär A. T. , Awala Ibrahim , Holmberg-Kasa Jacob , Krause Andreas M. , Tidefelt Mattias , Vigstrand Oscar , Music Denis
Published: July 2023

In the present work, we have used classical molecular dynamics and quantum mechanical density functional theory modeling to investigate the grain size-dependent thermal expansion coefficient (CTE) of nanocrystalline Cu. We find that the CTE increases by up to 20% with a gradually decreasing grain size. This behavior emerges as a result of the increased population of occupied anti-bonding states and bond order variation in the grain boundary regions, which contribute to the reduced resistance against thermally-induced bond stretching and dictate the thermal expansion behavior in the small grain size limit. As a part of the present work, we have established a procedure to produce ab initio thermal expansion maps that can be used for the prediction of the grain size-dependent CTE. This can serve as a modeling tool, e.g., to explore the impact of grain boundary impurity segregation on the CTE.
Damage Assessment of Glass-Fibre-Reinforced Plastic Structures under Quasi-Static Indentation with Acoustic Emission
Authors: Osa-uwagboe Norman , Udu Amadi Gabriel , Silberschmidt Vadim V. , Baxevanakis Konstantinos P. , Demirci Emrah
Published: July 2023

The use of fibre-reinforced plastics (FRPs) in various industrial applications continues to increase thanks to their good strength-to-weight ratio and impact resistance, as well as the high strength that provides engineers with advanced options for the design of modern structures subjected to a variety of out-of-plane impacts. An assessment of the damage morphology under such conditions using non-destructive techniques could provide useful data for material design and optimisation. This study investigated the damage mechanism and energy-absorption characteristics of E-glass laminates and sandwich structures with GFRP face sheets with PVC cores under quasi-static indentation with conical, square, and hemispherical indenters. An acoustic emission (AE) technique, coupled with a k-means++ pattern-recognition algorithm, was employed to identify the dominant microscopic and macroscopic damage mechanisms. Additionally, a post-mortem damage assessment was performed with X-ray micro computed tomography and scanning electron microscopy to validate the identified clusters. It was found that the specific energy absorption after impact with the square and hemispherical indenters of the GFRP sandwich and the plain laminate differed significantly, by 19.29% and 43.33%, respectively, while a minimal difference of 3.5% was recorded for the conical indenter. Additionally, the results obtained with the clustering technique applied to the acoustic emission signals detected the main damaged modes, such as matrix cracking, fibre/matrix debonding, delamination, the debonding of face sheets/core, and core failure. The results therefore could provide a methodology for the optimisation and prediction of damage for the health monitoring of composites.
Low Cholesterol Levels in Younger Heart Failure Patients May Predict Unfavorable Outcomes
Authors: Charach Lior , Grosskopf Itamar , Galin Leonid , Guterman Irit , Karniel Eli , Charach Gideon
Published: July 2023

Background and Objectives: Hypercholesterolemia is a main risk-factor leading to ischemic heart disease (IHD). However, among patients with heart failure, the use of lipid lowering drugs in the presence of low cholesterol might be dangerous. This 18-year longitudinal study of patients ≤51 years old investigated the relationship between baseline total cholesterol, low-density lipoprotein cholesterol (LDL-c) and triglyceride levels, and survival among patients with severe HF. Materials and Methods: The average NYHA score of 82 patients ≤51 years old with heart failure was 2.61. They were followed for a mean of 11.3 years (15 months–20 years). Total mortality was 22%. Patients were divided into three groups. Group 1 had plasma LDL-c levels ≤ 80 mg/dl, Group 2, 80–115 mg/dl and Group 3 > 115 mg/dl. Results: Patients with the highest baseline total cholesterol, triglyceride and LDL-c levels > 115 mg/dl had a better survival rate (83%) compared to those with LDL-c < 80 mg/dl (50% survival, p = 0.043). The association between higher LDL-c levels and lower mortality was most noticeable among patients with heart failure. Conclusion: Longitudinal follow-up found that low LDL-c levels may indicate poorer prognosis among patient with heart failure who are ≤51 years old, similar to elderly heart failure patients. Cholesterol lowering drugs in younger patients with heart failure may increase mortality.
Oxidation Effects on Short-Term Creep Response in Air of Commercially Pure Titanium (CP-2 Ti)
Authors: Regev Michael , Santoni Alberto , Spigarelli Stefano
Published: July 2023

The creep response in the air of commercially pure titanium was investigated at 550, 600, and 650 °C to assess the effect of oxidation on the mechanical response. Experiments demonstrated that prolonged exposures at high temperatures produced a marked reduction in the minimum creep rate under a given applied stress. Microhardness measurements showed that a hardened zone formed in proximity to the surface due to oxygen penetration into the metal. A simplified composite model was then used to describe the creep response. In this model, the sample consisted of two zones, the hard case that was enriched in oxygen and the soft pure-titanium core, both creeping with similar strain rates. Calculations led to an estimation of the dependence of the minimum creep rate on stress and temperature for the hard high-oxygen zone. The simplified composite model presented here provided a good description of the experimental creep data for pure titanium, tested in its air, and a reliable picture of the effect of oxidation on complex Ti alloys.
A High-Precision Current-Mode Bandgap Reference with Nonlinear Temperature Compensation
Authors: Chen Zhizhi , Wang Qian , Li Xi , Song Sannian , Chen Houpeng , Song Zhitang
Published: July 2023

A high-precision current-mode bandgap reference (BGR) circuit with a high-order temperature compensation is presented in this paper. In order to achieve a high-precision BGR circuit, the equation of the nonlinear current has been modified and the high-order term of the current flowing into the nonlinear compensation bipolar junction transistor (NLCBJT) is compensated further. According to the modified equation, two solutions are designed to improve the output accuracy of BGR circuits. The first solution is to divide the NLCBJT branch into two branches to reduce the coefficient of the nonlinear temperature compensation current. The second solution is to inject the nonlinear current into the two branches based on the first one to further eliminate the temperature coefficient (TC) of the current flowing into the NLCBJT. The proposed BGR circuit has been designed using the Semiconductor Manufacturing International Corporation (SMIC) 55 nm CMOS process. The simulation results show that the variations in currents flowing into NLCBJTs improved from 148.41 nA to 69.35 nA and 7.4 nA, respectively, the TC of the output reference current of the proposed circuit is approximately 3.78 ppm/°C at a temperature range of −50 °C to 120 °C with a supply voltage of 3.3 V, the quiescent current consumption of the entire BGR circuit is 42.13 μA, and the size of the BGR layout is 0.044 mm2, leading to the development of a high-precision BGR circuit.
Ag2S-Ag2O-Ag/poly-2-aminobenzene-1-thiol Nanocomposite as a Promising Two-Electrode Symmetric Supercapacitor: Tested in Acidic and Basic Mediums
Authors: Rabia Mohamed , Elsayed Asmaa M. , Abdallah Alnuwaiser Maha , Abdelazeez Ahmed Adel A.
Published: July 2023

A Ag2S-Ag2O-Ag/poly-2-aminobenzene-1-thiol (P2ABT) nanocomposite was prepared using the photopolymerization reaction using AgNO3 as an oxidant. The size of the nanocomposite was about 40 nm, in which the morphology was confirmed using TEM and SEM analyses. The functional groups of Ag2S-Ag2O-Ag/P2ABT were confirmed using FTIR; also, XRD confirmed the inorganic Ag2S, Ag, and Ag2O formation. This nanocomposite has great performance in supercapacitor applications, with it tested in acidic (1.0 M HCl) and basic mediums (1.0 M NaOH). This pseudo-capacitor has great performance that appeared through the charge time in an acid medium in comparison to the basic medium with values of 118 s and 103 s, correspondingly. The cyclic voltammetry (CV) analysis further confirmed the excellent performance of the supercapacitor material, as indicated by the large area under the cyclic curve. The specific capacitance (CS) and energy density (E) values (at 0.3 A/g) were 92.5 and 44.4 F/g and 5.0 and 2.52 W·h·Kg−1 in the acidic and basic mediums, correspondingly. The charge transfer was studied through a Nyquist plot, and the produced Rs values were 4.9 and 6.2 Ω, respectively. Building on these findings, our objective is to make a significant contribution to the progress of supercapacitor technology through a prototype design soon.
Effect of Drilling Parameters and Tool Geometry on the Thrust Force and Surface Roughness of Aerospace Grade Laminate Composites
Authors: Bolat Çağın , Karakılınç Uçan , Yalçın Bekir , Öz Yahya , Yavaş Çağlar , Ergene Berkay , Ercetin Ali , Akkoyun Fatih
Published: July 2023

Carbon fiber-reinforced plastics (CFRPs) have been specially developed to enhance the performance of commercial and military aircraft because of their strength, high stiffness-to-density ratios, and superior physical properties. On the other hand, fasteners and joints of CFRP materials may be weak due to occurring surface roughness and delamination problems during drilling operations. This study’s aim is to investigate the drilling characterization of CFRPs with different drilling parameters and cutting tools. Drilling tests were performed with the Taguchi orthogonal array design (L18: 2^1 3^3). Tests were conducted with three levels of cutting speed (15, 30, 45 m/min), three levels of feed rate (0.05, 0.1, 0.2 mm/rev), two levels of drill diameter (3 and 5 mm), and three different types of drills (two twist drills with a point angle of 138° and 120° and one brad drill). Thrust forces were recorded during drilling tests, and afterwards surface roughness and hole delamination were measured. Obtained results were analyzed with Taguchi and two-way ANOVA. The general tendency was that low cutting speed, high feed rate, and small diameter drill caused an increase in thrust force. Surface roughness decreases with increasing tool diameter, decreasing feed, and cutting speed. Delamination factors of the samples dropped depending on decreasing thrust force levels. Remarkably, it is possible to control the delamination factor values via better surface quality. The brad drill and larger point angle have a negative effect on the drilling quality of CFRPs. According to all results, the cutting speed of 45 m/min and feed rate of 0.05 mm/rev using a type II drill having a 120° point angle and 5 mm diameter (12th trial) and the cutting speed of 30 m/min and feed rate of 0.05 mm/rev using a type II drill having a 120° point angle and 3 mm diameter (2nd trial) were determined as optimum drilling conditions.