bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhancing Ecosystem Services in the Agro-Pastoral Transitional Zone Based on Local Sustainable Management: Insights from Duolun County in Northern China
Authors: Dai Luwei , Tang Haiping , Pan Yunlong , Liang Dalin
Published: May 2022

Ecosystem and associated ecosystem services (ESs) in the agro-pastoral transitional zone of northern China (APTZNC) are sensitive to climate change and human activities. Essential to designing targeted policy interventions toward achieving sustainability in the APTZNC is a comprehensive understanding of the spatiotemporal changes in ESs and their drivers. This study identified the spatiotemporal changes in six ESs in Duolun County from 2000 to 2017. The impacts of drivers—temperature, precipitation, wind speed, vegetation cover (FVC), land use/cover (LULC), soil type, altitude, and slope—on the changes in the ESs in the county and its ecological production zones were then explored. The results indicated that the six ESs improved during the study period. The drivers influencing changes in ESs over time exhibited similarities across regions. Although FVC contributed to improvements in the food supply, grass production, carbon sequestration, and soil wind erosion (SLwind), it also reduced water yield, which may exacerbate the water shortage in arid and semi-arid areas. In regions where the ecology was in the recovery phase, especially in slope farmland, the inhibition of soil water erosion (SLwater) by FVC was easily offset by the higher SLwater potential from increased precipitation. The decrease in wind speed improved the regional ESs, whereas the increase in temperature posed a threat to SLwind. The drivers affecting the spatial patterns of ESs varied among zones. Across the three zones, the greater influential drivers of ESs were FVC and LULC. The impacts of topographic drivers and soil type on the distribution of ESs should also be noted in the agro-zone and agro-pastoral zone, respectively. Our study advocated that ES management should be adjusted to local conditions, and differentiated planning policies should be implemented in line with the ecological characteristics in the APTZNC, which will contribute to regional ecological sustainable development.
The Effects of Climate Change on Habitat Connectivity: A Case Study of the Brown-Eared Pheasant in China
Authors: Cao An , Shi Xueyi
Published: May 2022

Climate change has caused habitat fragmentation and reduced connectivity. The Fen River Basin in Shanxi Province, China is an important habitat for the central population of the brown-eared pheasant (BEP). The effects of climate change need to be considered in the conservation planning of BEP habitats. We used a species dispersion model to determine the BEP core habitat and graph theory to explore the connectivity of the BEP’s main habitats. The pinch point areas of BEP dissemination were determined by circuit theory. Least-cost pathways were used to identify the critical corridors for BEP dissemination. A gap analysis was conducted to estimate the efficiency of BEP conservation measures. Under the future climate scenarios, BEP habitats decreased by between 54.69% and 97.63%, and the connectivity of the main habitats was reduced by a similar magnitude. The BEP core habitat shifted to the southwestern region under the influence of climatic conditions. Currently, 90.84% of the species’ critical habitat remains unprotected. Due to climate change, the core habitat in the future was projected to differ from the current protected area. Enhancing the protection of the pinch point region may aid in the restoration of habitat connectivity.
Ultrasound-Guided PECS II + Serratus Plane Fascial Blocks Are Associated with Reduced Opioid Consumption and Lengths of Stay for Minimally Invasive Cardiac Surgery: An Observational Retrospective Study
Authors: Torre Debora Emanuela , Pirri Carmelo , Contristano Marialuisa , Behr Astrid Ursula , De Caro Raffaele , Stecco Carla
Published: May 2022

This study tested the hypothesis that pectoralis II (PECS II) + serratus plane blocks would reduce opioid consumption and improve outcomes compared with standard practice in minimally invasive cardiac surgery. A retrospective and observational study was realized in the intensive care unit (ICU) setting of “ICLAS GVM, Istitituto Clinico Ligure Alta Specialità, (Rapallo, Italy)”, including adult patients who underwent right minithoracotomy for replacement/plastic aortic, mitral and tricuspid valve or atrial myxoma resection in cardiac surgery. Seventy-eight patients were extracted by the database and divided into two groups. Group 1 (41 patients) received ultrasound-guided PECS II + serratus plane blocks with Ropivacaine 0.25% 10 mL + 20 mL + 30 mL. Group 2 (37 patients) received intravenous opioids analgesia with morphine 20–25 mg/day or tramadol 200–300 mg/day. The primary outcomes were: the pain perceived: Critical-Care Pain Observation Tool (CPOT) score; the opioids consumption: mg morphine or tramadol, or µg sufentanyl administered; and mg paracetamol, toradol, tramadol or morphine administered as a rescue. The secondary outcomes were the hours of orotracheal intubation and of stay in ICU, and the number of episodes of nausea, vomiting, delayed awakening and respiratory depression. Group 1 vs. Group 2 consumed less opioids (Sufentanyl p < 0.0001; Morphine p < 0.0001), had a lower pain perceived (p = 0.002 at 6 h, p = 0.0088 at 12 h, p < 0.0001 at 24 h), need for rescue analgesia (p = 0.0005), episodes of nausea and vomiting (p = 0.0237) and intubation time and ICU stay (p = 0.0147 time of IOT, p < 0.0001 stay in ICU). Ultrasound-guided PECS II + serratus plane blocks demonstrated better than intravenous opioids analgesia in patients undergoing minimally invasive cardiac surgery.
Identifying COVID-19 Severity-Related SARS-CoV-2 Mutation Using a Machine Learning Method
Authors: Huang Feiming , Chen Lei , Guo Wei , Zhou Xianchao , Feng Kaiyan , Huang Tao , Cai Yudong
Published: May 2022

SARS-CoV-2 shows great evolutionary capacity through a high frequency of genomic variation during transmission. Evolved SARS-CoV-2 often demonstrates resistance to previous vaccines and can cause poor clinical status in patients. Mutations in the SARS-CoV-2 genome involve mutations in structural and nonstructural proteins, and some of these proteins such as spike proteins have been shown to be directly associated with the clinical status of patients with severe COVID-19 pneumonia. In this study, we collected genome-wide mutation information of virulent strains and the severity of COVID-19 pneumonia in patients varying depending on their clinical status. Important protein mutations and untranslated region mutations were extracted using machine learning methods. First, through Boruta and four ranking algorithms (least absolute shrinkage and selection operator, light gradient boosting machine, max-relevance and min-redundancy, and Monte Carlo feature selection), mutations that were highly correlated with the clinical status of the patients were screened out and sorted in four feature lists. Some mutations such as D614G and V1176F were shown to be associated with viral infectivity. Moreover, previously unreported mutations such as A320V of nsp14 and I164ILV of nsp14 were also identified, which suggests their potential roles. We then applied the incremental feature selection method to each feature list to construct efficient classifiers, which can be directly used to distinguish the clinical status of COVID-19 patients. Meanwhile, four sets of quantitative rules were set up, which can help us to more intuitively understand the role of each mutation in differentiating the clinical status of COVID-19 patients. Identified key mutations linked to virologic properties will help better understand the mechanisms of infection and will aid in the development of antiviral treatments.
No Reduction in Yield of Young Robusta Coffee When Grown under Shade Trees in Ecuadorian Amazonia
Authors: Piato Kevin , Subía Cristian , Lefort François , Pico Jimmy , Calderón Darío , Norgrove Lindsey
Published: May 2022

Little is known on what impact shade trees have on the physiology of Coffea canephora (robusta coffee) under tropical humid conditions. To fill this gap, a field experiment was conducted in the Ecuadorian Amazon to investigate how growth, nutrition (leaf N), phenological state (BBCH-scale) and yield of 5-year-old robusta coffee shrubs are affected by the presence or absence of leguminous trees, the type (organic v conventional) and intensity of management. The experiment was a factorial 5 × 4 design with four cropping systems: intensive conventional (IC), moderate conventional (MC), intensive organic (IO) and low organic (LO), and with five shading systems in a split-plot arrangement: full sun (SUN), both Erythrina spp. and Myroxylon balsamum (TaE), M. balsamum (TIM), E. spp. (ERY) and Inga edulis (GUA). Three monthly assessments were made. Cherry yields of coffee shrubs under moderate shade (c. 25%) were similar to those under high light exposure. Coffee shrubs grown with either E. spp. or I. edulis were taller (+10%) and had higher leaf N concentrations (22%) than those grown without consistent shade. Unless receiving c. 25% of shade, coffee shrubs grown under organic cropping systems showed reduced growth (25%). No correlation was found between height, cherry yield and leaf N. Both shading and cropping systems affected leaf N concentration, also depending on phenological state and yield. Further research is needed to confirm our findings in the long-term as well as to elucidate how leguminous trees may induce physiological responses in robusta coffee under humid tropical conditions.
Effects of Hypoxia Stress on Growth, Root Respiration, and Metabolism of Phyllostachys praecox
Authors: Ma Jiawei , Rukh Gul , Ruan Zhongqiang , Xie Xiaocui , Ye Zhengqian , Liu Dan
Published: May 2022

Hypoxia affects plant growth, hormone content, various enzyme activities, cell structure, peroxide production, and metabolic level, therefore reducing crop yield. This study assessed the physiological, biochemical, and metabolic characteristics of Phyllostachys praecox. Results revealed that hypoxia stress treatment significantly inhibited plant growth. Leaf chlorophyll contents was initially improved and then reduced with plant growth time. Under hypoxia stress, the root activity significantly was reduced, leading to the decrease in the nutrient absorption and transport. Yet, with low oxygen concentration, the contents of ethanol, acetaldehyde, and lactic acid were improved. With hypoxia stress, phospholipids and amino acids were the main metabolites of Phyllostachys praecox. Glycosphospholipid metabolism is the key pathway in responding to hypoxia stress significantly (p < 0.05), and lysophosphatidlycholine (lysoPC) and phosphatidylcholines (PC) in the metabolites of this metabolic pathway were significantly enhanced. Our study reveals the mechanism of Phyllostachys praecox cell membrane responding to hypoxia stress based on molecular level. This is conducive to finding targeted solutions to improve the productivity of Phyllostachys praecox to better optimize a mulching approach in the bamboo forest.
Fetal Brain Development: Regulating Processes and Related Malformations
Authors: Leibovitz Zvi , Lerman-Sagie Tally , Haddad Leila
Published: May 2022

This paper describes the contemporary state of knowledge regarding processes that regulate normal development of the embryonic–fetal central nervous system (CNS). The processes are described according to the developmental timetable: dorsal induction, ventral induction, neurogenesis, neuronal migration, post-migration neuronal development, and cortical organization. We review the current literature on CNS malformations associated with these regulating processes. We specifically address neural tube defects, holoprosencephaly, malformations of cortical development (including microcephaly, megalencephaly, lissencephaly, cobblestone malformations, gray matter heterotopia, and polymicrogyria), disorders of the corpus callosum, and posterior fossa malformations. Fetal ventriculomegaly, which frequently accompanies these disorders, is also reviewed. Each malformation is described with reference to the etiology, genetic causes, prenatal sonographic imaging, associated anomalies, differential diagnosis, complimentary diagnostic studies, clinical interventions, neurodevelopmental outcome, and life quality.
Synechococcus elongatus PCC 7942 as a Platform for Bioproduction of Omega-3 Fatty Acids
Authors: Santos-Merino María , Gutiérrez-Lanza Raquel , Nogales Juan , García José Luis , de la Cruz Fernando
Published: May 2022

Alpha-linolenic acid and stearidonic acid are precursors of omega-3 polyunsaturated fatty acids, essential nutrients in the human diet. The ability of cyanobacteria to directly convert atmospheric carbon dioxide into bio-based compounds makes them promising microbial chassis to sustainably produce omega-3 fatty acids. However, their potential in this area remains unexploited, mainly due to important gaps in our knowledge of fatty acid synthesis pathways. To gain insight into the cyanobacterial fatty acid biosynthesis pathways, we analyzed two enzymes involved in the elongation cycle, FabG and FabZ, in Synechococcus elongatus PCC 7942. Overexpression of these two enzymes led to an increase in C18 fatty acids, key intermediates in omega-3 fatty acid production. Nevertheless, coexpression of these enzymes with desaturases DesA and DesB from Synechococcus sp. PCC 7002 did not improve alpha-linolenic acid production, possibly due to their limited role in fatty acid synthesis. In any case, efficient production of stearidonic acid was not achieved by cloning DesD from Synechocystis sp. PCC 6803 in combination with the aforementioned DesA and DesB, reaching maximum production at 48 h post induction. According to current knowledge, this is the first report demonstrating that S. elongatus PCC 7942 can be used as an autotrophic chassis to produce stearidonic acid.
Accuracy of 3D Tooth Movements in the Fabrication of Manual Setup Models for Aligner Therapy
Authors: Sabbagh Hisham , Heger Sebastian Marcus , Stocker Thomas , Baumert Uwe , Wichelhaus Andrea , Hoffmann Lea
Published: May 2022

Background: The clinical outcome of aligner therapy is closely related to the precision of its setup, which can be manually or digitally fabricated. The aim of the study is to investigate the suitability of manual setups made for aligner therapy in terms of the precision of tooth movements. Methods: Six dental technicians were instructed to adjust each of eleven duplicate plaster casts of a patient models as follows: a 1 mm pure vestibular translation of tooth 11 and a 15° pure mesial rotation of tooth 23. The processed setup models were 3D scanned and matched with the reference model. The one-sample Wilcoxon signed-rank test (p < 0.05) was used for evaluation. Results: The overall precision of the translational movement covers a wide range of values from 0.25 to 2.26 mm (median: 1.09 mm). The target value for the rotation of tooth 23 was achieved with a median rotation of 9.76° in the apical-occlusal direction. Unwanted movements in the other planes also accompanied the rotation. Conclusions: A manual setup can only be fabricated with limited precision. Besides the very high variability between technicians, additional unwanted movements in other spatial planes occurred. Manually fabricated setups should not be favored for aligner therapy due to limited precision.
Study on the Influence of Selected Fabrics and Stitching on the Strength of Upholstery Covers
Authors: Lange Julia , Ciura Agata , Majewski Adam , Wojnowska Marlena
Published: May 2022

So far, no coherent and comprehensive method has been elaborated allowing investigation of tensile strength of upholstery seams dedicated to upholstered furniture. Producers of this type of furniture are interested in the assessment of the quality of upholstery material joints, which seems to be particularly important for ensuring the appropriate quality of products. Therefore, the objective of this research was to investigate the influence of the type of material used and the direction of the fabric cut on the strength of upholstery covers. Static tensile testing of selected upholstery fabric samples was performed, and an attempt was made to identify the most optimal fabric–seam joints. It was stated as a conclusion that the fabric tensile strength was the highest for Secret 10 fabric. In addition, the strength of upholstery covers is not influenced by the direction of the fabric die cut. For each fabric, a different configuration is preferable, as shown by results (Power 13: A-B, Secret 10: B-B, Soft 10: A-A). The method, implemented for upholstered furniture, allows for an objective assessment of the strength of upholstery covers and the selection of the most advantageous fabric–seam combination for future furniture designs.
Study on Intrinsic Influence Law of Specimen Size and Loading Speed on Charpy Impact Test
Authors: Jia Wang , Pi Aiguo , Zhao Zhang , Wang Shaohong , Wei Chen , Jie Zhou , Huang Fenglei
Published: May 2022

Charpy impact energy/impact toughness is closely related to external factors such as specimen size. However, when the sample size is small, the linear conversion relationship between the Charpy impact energy of the sub-size and full-size Charpy specimens does not hold; the Charpy impact toughness varies with the size of the specimen and other factors. This indicates that studying the internal influence of external factors on impact energy or impact toughness is the key to accurately understanding and evaluating the toughness and brittleness of materials. In this paper, the effects of strain rate on the flow behavior and the effects of stress triaxiality on the fracture behavior of 30CrMnSiNi2A high-strength steel were investigated using quasi-static smooth bar and notched bar uniaxial tensile tests and Split Hopkinson Tensile Bar (SHTP). Based on the flow behavior and strain rate dependences of the yield behavior, a modified JC model was established to describe the flow behavior and strain rate behavior. Charpy impact tests were simulated using the modified JC model and JC failure model with the determined parameters. Reasonable agreements between the simulation and experimental results have been achieved, and the validity of the model was proved. According to the simulation results, the impact energy was divided into crack initiation energy, crack stability propagation energy and crack instability propagation energy. On this basis, the effects of striker velocity and specimen width on the energy and characteristic load of each part were studied. The results show that each part of the impact energy has a negligible dependence on the hammer velocity, but there is a significantly different positive linear relationship with the width of the sample. The energy increment of each part also showed an inverse correlation with the increase in the sample width. The findings reveal that the internal mechanism of Charpy impact toughness decreases with the increase in sample width; to a certain extent, it also reveals the internal reason why the linear transformation relationship of Charpy impact energy between sub-size specimens and standard specimens is not established when the specimens are small. The analytical method and results presented in this paper can provide a reference for the study of the dynamic behavior of high-strength steel, the relationship between material properties and sample size, and the elastic–plastic impact dynamic design.
Pore Structure Characteristics and Strength Variation of Red Sandstone under Freeze–Thaw Cycles
Authors: Lan Yongwei , Gao Hongmei , Zhao Yanlin
Published: May 2022

To study pore structure characteristics and the strength of red sandstone under freeze–thaw cycles, the saturated red sandstone was studied by the combination of freeze–thaw cycle test, high-pressure mercury injection test, uniaxial compression test and theoretical analysis, and research shows that: with the increase of freeze–thaw cycles, the pores of red sandstone continue to expand and extend, macropore volume and the total pore volume increases gradually, and the pore size distribution curves become more continuous. Porosity of samples after 10, 30, 70 and 100 freeze–thaw cycles is 1.14 times, 1.17 times, 1.28 times and 1.44 times of that of 0 cycle, and the uniaxial compressive strength of samples is 0.68 times, 0.53 times, 0.26 times and 0.17 times of that of 0 cycle, respectively. With the increase of freeze–thaw cycles, freeze–thaw damage continues to accumulate, the crack propagation direction changes from axial through-through failure mode to transverse and axial simultaneous failure mode. Taken the change of porosity as a parameter, through the regression analysis of the test data, the functional relationship between uniaxial compressive strength and the change of porosity in red sandstone is established. The research results will provide a theoretical basis for stability research of slopes of railway subgrade in cold region.
Experimental and Analytical Modeling of Flexural Impact Strength of Preplaced Aggregate Fibrous Concrete Beams
Authors: Murali Gunasekaran , Abid Sallal Rashid , Vatin Nikolai Ivanovich
Published: May 2022

Preplaced aggregate fibrous concrete (PAFC) is a revolutionary kind of concrete composite that is gaining popularity and attracting the interest of academics from across the world. PAFC is a uniquely designed concrete prepared by stacking and packing premixed fibers and coarse aggregate in a steel mold. The gaps between the fibers and aggregates are subsequently filled by injecting a cement grout with high flowability. This study investigates the impact performance of three different sizes of PAFC beams. Steel and polypropylene fibers were used in a 3% dosage to make three different beam sizes, measuring 550 × 150 × 150 mm, 400 × 100 × 100 mm, and 250 × 50 × 50 mm. According to ACI Committee 544, all beams were subjected to a drop weight flexural impact test. Compressive strength, impact energies at initial crack and failure, ductility index, and failure mode were evaluated. Additionally, analytical modeling was used to compute the failure impact energy for the fibrous beams. The results showed that the addition of fibers increased the capacity of the tested beams to absorb greater flexural impact energy. Compared to polypropylene fibers, steel fibers had better crack propagation and opening resistance because of their higher tensile strength and crimped and hooked end configuration. For all large-size beams, the analysis of the percentage increase in impact energy at the failure stages was found to be 5.3 to 14.6 times higher than the impact energy at cracking.
Wear Mechanisms and Notch Formation of Whisker-Reinforced Alumina and Sialon Ceramic Tools during High-Speed Turning of Inconel 718
Authors: Xue Chao , Wang Dong , Zhang Jingjing
Published: May 2022

Nickel-based alloys, referred to as the most difficult-to-cut materials, pose a great challenge to cutting tool materials due to their excellent high-temperature properties. Ceramic tools have the potential to improve the machinability of these alloys with the advance of toughening mechanisms. In this work, the wear mechanisms of SiC whisker-reinforced alumina and Sialon when high-speed turning Inconel 718 alloy under dry cutting condition were investigated. The results showed that the wear process of Al2O3-SiCw WG300 was dominated by the notch wear, while the flank wear characterized by ridges and grooves perpendicular to the cutting edge was the main wear mode for Sialon SX9. A Ti−enriched belt was found at the boundary of the wear band for both ceramic tools. The SEM inspection and EDS analysis for this belt suggested the trace of diffusion between the workpiece material and tool matrix. As for the notch formation, the periodically adhesive action of the workpiece material at the depth-of-cut line combined with the thermal shock resistance of ceramic tools were considered to account for its formation. In addition, the oxidation of the workpiece material at the depth-of-cut line played a positive role in reducing the adhesive affinity and consequent notch wear.
Study on Milling Force and Surface Quality during Slot Milling of Plain-Woven CFRP with PCD Tools
Authors: Xu Ziyang , Wang Yongguo
Published: May 2022

Carbon-fiber-reinforced polymers (CFRPs) have been widely used in many industrial fields, such as automobile, aerospace and so on, because of their excellent mechanical properties. However, due to their anisotropy and inhomogeneity, machining CFRPs is a great challenge. In this paper, the slot milling of a plain-woven CFRP with PCD tools is carried out, and the effects of cutting parameters and tool rake angle on cutting force and surface roughness are studied. The results show that the 4° rake angle PCD tool has smaller cutting force than the 0° rake angle PCD tool, but the effect of rake angle on surface roughness is not significant. The concept of equivalent cutting area is introduced to study the variation law of cutting force and surface roughness. It is found that the cutting force and surface roughness increase with the increase in equivalent cutting area, and decrease with the decrease in equivalent cutting area. The removal mechanism of surface materials under different equivalent cutting areas is different, which leads to the difference in surface roughness. Finally, the causes of delamination on the top layer after milling are explained.
Electronic Properties and Structure of Silicene on Cu and Ni Substrates
Authors: Galashev Alexander , Vorob’ev Alexey
Published: May 2022

Silicene, together with copper or nickel, is the main component of electrodes for solar cells, lithium-ion batteries (LIB) and new-generation supercapacitors. The aim of this work was to study the electronic properties and geometric structure of “silicene–Ni” and “silicene–Cu” systems intended for use as LIB electrodes. The densities of electronic states, band structures, adhesion energies and interatomic distances in the silicene–(Cu, Ni) systems were determined by ab initio calculations. Silicene on a copper substrate exhibited temperature stability in the temperature range from 200 to 800 K, while on a nickel substrate, the structure of silicene was rearranged. Adsorption energies and bond lengths in the “silicene–Cu” system were calculated in the range of Li/Si ratios from 0.125 to 0.5. The formation of the Li2 isomer during the adsorption of lithium in a ratio to silicon of 0.375 and 0.5 was observed. Silicene was found to remain stable when placed on a copper substrate coated with a single layer of nickel. The charge redistribution caused by the addition of a nickel intermediate layer between silicene and a copper substrate was studied.
An Efficient Dopant for Introducing Magnetism into Topological Insulator Bi2Se3
Authors: Wang Dan , Hu Cui-E , Liu Li-Gang , Zhang Min , Chen Xiang-Rong
Published: May 2022

In this work, we obtained an effective way to introduce magnetism into topological insulators, and successfully fabricated single crystal C-Bi2Se3. The structural, electrical and magnetic properties of non-magnetic element X (B, C and N) doped at Bi, Se1, Se2 and VDW gap sites of Bi2Se3 were studied by the first principles. It is shown that the impurity bands formed inside the bulk inverted energy gap near the Fermi level with C doping Bi2Se3. Due to spin-polarized ferromagnetic coupling, the time inversion symmetry of Bi2Se3 is destroyed. Remarkably, C is the most effective dopant because of the magnetic moment produced by doping at all positions. The experiment confirmed that the remnant ferromagnetism Mr is related to the C concentration. Theoretical calculations and experiments confirmed that carbon-doped Bi2Se3 is ferromagnetic, which provides a plan for manipulating topological properties and exploring spintronic applications.
Investigating Biochar-Derived Dissolved Organic Carbon (DOC) Components Extracted Using a Sequential Extraction Protocol
Authors: Liu Hui , Zhao Baowei , Zhang Xin , Li Liujun , Zhao Yue , Li Yingquan , Duan Kaixiang
Published: May 2022

Biochar-derived dissolved organic carbon (DOC), as the most important component of biochar, can be released on farmland, improving fertility and playing a role in soil amendment and remediation. The complexity of molecular structures and diversity of DOC compounds have influenced these functions to some extent. A sequential extract protocol consisting of water (25 °C), hot water (80 °C), and NaOH solution (0.05 M) was used to fully extract DOC compounds and gain a thorough understanding of the possible DOC components released from biochar. Rape straw (RS), apple tree branches (ATB), and pine sawdust (PS) were pyrolyzed at 300, 500, and 700 °C, respectively, to make nine distinct biochars. A TOC analyser, ultraviolet-visible spectroscopy (UV–vis), and excitation–emission fluorescence (EEM) spectrophotometer were used in conjunction with parallel factor analysis (PARAFAC) to determine the distribution of DOC content, the diversity of aromaticity, molecular weight characteristics and components of biochar-derived DOC. The results show that the relative distribution of water-extractable fractions ranged from 3.21 to 35.57%, with a low-aromaticity and extremely hydrophilic fulvic-acid-like compounds being found in the highest amounts (C2 and C3). The smallest amount of hot water-extractable components was produced from the release of small-molecule aliphatic compounds adsorbed on biochar and susceptible to migration loss once in a soil solution. More than half of the biochar-derived DOC was released in a NaOH solution, which primarily consisted of humic-acid-like compounds (C1), with higher molecular weights, more aromaticity, and lower bioavailability, according to the distribution of DOC in various extractants. In addition, the pyrolysis temperature and biomass type had a significant impact on the DOC properties released by biochar. As a result, the findings of this study showed that using a sequential extract protocol of water, hot water, and NaOH solution in combination with spectroscopic methods could successfully reveal the diversity of biochar-derived components, which could lead to new insights for the accurate assessment of potential environmental impacts and new directions for biochar applications.
Application of Iron Tailings-Based Composite Supplementary Cementitious Materials (SCMs) in Green Concrete
Authors: Zhang Yannian , Yang Daokui , Gu Xiaowei , Chen Hao , Li Zhijun
Published: May 2022

How to treat the iron tailings of mining solid waste with high value is an urgent problem on a global scale. In recent years, the application of iron tailings in the building materials industry has attracted the attention of many scholars. The conversion of iron tailings into green building materials helps achieve carbon neutrality and high-value utilization of solid waste, and promotes sustainable development. Although iron tailings have been extensively studied as supplementary cementitious materials, the performance of concrete is not ideal due to its low activity. In this study, the hybrid supplementary cementitious materials system was prepared by iron tailings, phosphorus slag, and steel slag, and the effects of supplementary cementitious materials type, iron tailings content, iron tailings grinding time, and supplementary cementitious materials content on concrete performance were studied. The compressive properties, iron tailings properties, pore structure, interfacial transition zone, and element distribution of hydration products of concrete were tested by compressive strength tests, X-ray Diffractometer (XRD), X-ray Photoelectron Spectroscopy (XPS), Mercury Intrusion Porosimetry (MIP), Backscattering Electron Tests (BSE), and Energy Dispersive Spectrometer (EDS). The results show that further grinding improves the iron tailings activity. There is a synergistic mechanism between steel slag and phosphorus slag in the composite supplementary cementitious materials, which overcomes the low activity defect of iron tailings and produces concrete with a compressive strength exceeding 40 MPa. The composite supplementary cementitious materials can optimize the interfacial transition zone of the concrete interface and reduce the calcium–silicon ratio of the hydration products. However, it will deteriorate the pore structure of the concrete matrix, cause part of the concrete matrix to be damaged and lead to a loss of compressive strength, and the loss is acceptable. This work broadens the methods of comprehensive utilization of iron tailings and also provides a reference for a more detailed understanding of the properties of iron tailings-based concrete.
Assessment of Conventionally and Digitally Fabricated Complete Dentures: A Comprehensive Review
Authors: Mubaraki Manal Q. , Moaleem Mohammed M. Al , Alzahrani Abdulrahman H. , Shariff Mansoor , Alqahtani Saeed M. , Porwal Amit , Al-Sanabani Fuad A. , Bhandi Shilpa , Tribst João Paulo Mendes , Heboyan Artak , Patil Shankargouda
Published: May 2022

CAD/CAM technology is gaining popularity and replacing archaic conventional procedures for fabricating dentures. CAD/CAM supports using a digital workflow reduce the number of visits, chair time, and laboratory time, making it attractive to patients. This study aimed to provide a comparative review of complete dentures manufactured using CAD/CAM and conventional methods. The PubMed/Medline, Science Direct, Cochrane, and Google Scholar databases were searched for studies published in English within the last 11 years (from 2011 to 2021). The keywords used were “computer-engineered complete dentures”, “CAD/CAM complete dentures”, “computer-aided engineering complete dentures”, and “digital complete dentures”. The search yielded 102 articles. Eighteen relevant articles were included in this review. Overall, computer-engineered complete dentures have several advantages over conventional dentures. Patients reported greater satisfaction with computer-engineered complete dentures (CECDs) due to better fit, reduced chair time, shorter appointments, and fewer post-insertion visits. CAD/CAM allows for precision and reproducibility with fewer procedures compared to conventional dentures. Polymethyl methacrylate is used as the denture base material for conventional dentures. For CECDs, the resin can be modified and cross-linked to improve its mechanical properties. The advantages of CECDs include a reduced number of appointments, saving chairside time, a digital workflow allowing easy reproducibility and greater patient satisfaction with a better fit.
Effect of Carbon Nanofibers on Physical, Adhesion and Rheological Properties of Liquid Epoxidized Natural Rubber Modified Asphalt
Authors: Al-Mansob Ramez A. , Katman Herda Yati , Al-Sabaeei Abdulnaser M. , Zamzami Muhammad , Al-Fakih Amin , Wei Willy Kuay , Jassam Taha M. , Alsharef Jamal , Surol Salihah B. , Yusof Nurul H. , Koting Suhana
Published: May 2022

This study aimed to evaluate the effects of carbon nanofibers (CNFs) on the performance of liquid epoxidized natural rubber (LENR)-modified asphalt. The physical, adhesion and rheological properties were determined by several tests such as penetration, elastic recovery, ring and ball softening point, Brookfield rotational viscometer, AFM and dynamic shear rheometer. LENR was used at concentrations of 3, 6, and 9%, while CNFs were used at contents of 0.3, 0.4, and 0.5% by weight of asphalt. Conventional test results showed that the increases in LENR and LENR/CNFs composite contents in binder leads to an increase in the hardness and consistency and a reduction in the temperature susceptibility of base asphalt. Adhesion results revealed that the addition of CNFs significantly increases the adhesion and bonding properties of base and rubberized binders. Rheological properties analysis exhibited that LENR improved the viscoelastic properties and permanent deformation resistance of asphalt at different temperatures and frequencies. On the other hand, it was found that the addition of CNFs significantly improves the stiffness, elasticity, and hardness of LENR-modified binders. The 6% LENR and 0.4% CNFs were found to be the optimum to enhance the physical, adhesion, and rheological properties of asphalt in this study. Thus, it can be stated that the addition of CNFs is promising to improve the performance of rubberized binders for high temperature applications.
High-Speed Micro-Particle Motion Monitoring Based on Continuous Single-Frame Multi-Exposure Technology
Authors: Wang Wei , Xue Weiwei , Wu Shufan , Mu Zhongcheng , Yi Jiyuan , Tang Andrew J.
Published: May 2022

The impact phenomena of solid micro-particles have gathered increasing interest across a wide range of fields, including space debris protection and cold-spray additive manufacturing of large, complicated structures. Effective motion monitoring is essential to understanding the impact behaviors of micro-particles. Consequently, a convenient and efficient micro-particle motion monitoring solution is proposed based on continuous single-frame multiple-exposure imaging technology. This method adopts a camera with excellent low-light performance coupled with high-frequency light-emitting diode (LED) flashes to generate short interval illumination. This technology can, in theory, achieve 1 million effective frames per second (fps) and monitor particles as small as 10 microns with speeds up to 12 km/s. The capabilities of the proposed method were validated by a series of micro-particle motion monitoring experiments with different particles sizes and materials under varying camera configurations. The study provides a feasible and economical solution for the velocity measurement and motion monitoring of high-speed micro-particles.
Theoretical Prediction of Structures and Properties of 2,4,6-Trinitro-1,3,5-Triazine (TNTA) Green Energetic Materials from DFT and ReaxFF Molecular Modeling
Authors: Zhou Ming-Ming , Xiang Dong
Published: May 2022

Nitryl cyanide, O2NCN, as a new high-energy molecule, has not yet been successfully synthesized. It has prompted us to conduct a theoretical study of its possible space structures and properties. The RESP charges and the most stable spatial structures demonstrate that crystal morphology is affected by both the main nonbonded interactions and the molecular arrangement. The crystal structure prediction indicated that there are seven structures, namely P1, P21, P212121, P21/c, Pna21, Pbca, and C2/c. The most stable space structure is likely to be Pna21 and the corresponding cell parameters are Z = 4, a = 8.69 Å, b = 9.07 Å, c = 9.65 Å, and α = β = γ = 90.0°. To further study the intermolecular interactions of TNTA, a series of theoretical analyses were employed, including Hirshfeld surface analysis and fingerprint plots. The pyrolysis mechanism and properties show that high temperatures can promote decomposition. The systematic search approach can be a new strategy to identify structures effectively and has the potential to provide systematic theoretical guidance for the synthesis of TNTA.
Dual-Scale Porosity Alumina Structures Using Ceramic/Camphene Suspensions Containing Polymer Microspheres
Authors: Lee Hyun , Jeon Jong-Won , Koh Young-Hag , Kim Hyoun-Ee
Published: May 2022

This study demonstrates the utility of thermo-regulated phase separable alumina/camphene suspensions containing poly(methyl methacrylate) (PMMA) microspheres as porogens for the production of multi-scale porosity structures. The homogeneous suspension prepared at 60 °C could undergo phase separation during freezing at room temperature. This process resulted in the 3D networks of camphene crystals and alumina walls containing PMMA microspheres. As a consequence, relatively large dendritic pores with several tens of microns size could be created as the replica of frozen camphene crystals. In addition, after the removal of PMMA microspheres via heat-treatment, micron-sized small spherical pores could be generated in alumina walls. As the PMMA content with respect to the alumina content increased from 0 vol% to 40 vol%, while the camphene content in the suspensions was kept constant (70 vol%), the overall porosity increased from 45.7 ± 0.5 vol% to 71.4 ± 0.5 vol%. This increase in porosity is attributed to an increase in the fraction of spherical pores in the alumina walls. Thus, compressive strength decreased from 153 ± 18.3 MPa to 33 ± 7.2 MPa. In addition, multi-scale porosity alumina objects with a honeycomb structure comprising periodic hexagonal macrochannels surrounded by dual-scale porosity walls were constructed using a 3D plotting technique.
Microstructural Characterization of Additively Manufactured Metal Components Using Linear and Nonlinear Ultrasonic Techniques
Authors: Park Seong-Hyun , Choi Sungho , Song Dong-Gi , Jhang Kyung-Young
Published: May 2022

Metal additive manufacturing (AM) is an innovative manufacturing technology that uses a high-power laser for the layer-by-layer production of metal components. Despite many achievements in the field of AM, few studies have focused on the nondestructive characterization of microstructures, such as grain size and porosity. In this study, various microstructures of additively manufactured metal components were characterized non-destructively using linear/nonlinear ultrasonic techniques. The contributions of this study are as follows: (1) presenting correlation analyses of various microstructures (grain size and texture, lack of fusion, and porosity) and ultrasonic properties (ultrasonic velocity, attenuation, and nonlinearity parameters), (2) development of nondestructive microstructural characterization techniques for additively manufactured components; and (3) exploring the potential for the online monitoring of AM processes owing to the nondestructive nature of the proposed technique. The performance of the proposed technique was validated using additively manufactured samples under varying laser beam speed conditions. The characteristics of the target microstructures characterized using the proposed technique were consistent with the results obtained using destructive optical microscopy and electron back-scattered diffraction methods.
Bio-Synthesis of Aspergillus terreus Mediated Gold Nanoparticle: Antimicrobial, Antioxidant, Antifungal and In Vitro Cytotoxicity Studies
Authors: Mishra Rahul Chandra , Kalra Rishu , Dilawari Rahul , Goel Mayurika , Barrow Colin J.
Published: May 2022

Gold nanoparticles (GNP) were bio-fabricated utilizing the methanolic extract of the endophytic isolate Aspergillus terreus. The biosynthesised gold nanoparticles (GNP023) were characterised using UV-visible spectroscopy (UV-Vis); transmission electron microscopy (TEM), Fourier-transform nfrared spectroscopy (FTIR) and X-ray diffraction (XRD) studies. The bio-fabricated GNP023 displayed a sharp SPR peak at 536 nm, were spherically shaped, and had an average size between 10–16 nm. The EDX profile confirmed the presence of gold (Au), and XRD analysis confirmed the crystalline nature of GNP023. The antimicrobial activity of GNP023 was investigated against several food-borne and phytopathogens, using in vitro antibacterial and antifungal assays. The maximum zone of inhibition was observed for S. aureus and V. cholera at 400 μg /mL, whereas inhibition in radial mycelial growth was observed against Fusarium oxysporum and Rhizoctonia solani at 52.5% and 65.46%, respectively, when challenged with GNP023 (200 μg/mL). Moreover, the gold nanoparticles displayed significant antioxidant activity against the ABTS radical, with an IC50 of 38.61 µg/mL, and were non-toxic when tested against human kidney embryonic 293 (HEK293) cells. Thus, the current work supports the application of myco-synthesised gold nanoparticles as a versatile antimicrobial candidate against food-borne pathogens.
Study on Meso-Material Parameters of Submarine Weathered Granite Based on Parallel Bond Model
Authors: Zhang Shilei , Zhang Bonan , Han Bo , Zhang Qiyue , Liu Di
Published: May 2022

In order to study the mechanical properties of submarine weathered granite under marine geological conditions, uniaxial compression tests were carried out on the original medium weathered granite of the seafloor of an offshore area in Pingtan, Fujian Province by using triaxial experimental apparatus to analyze the fracture characteristics, stress–strain characteristics, and compressive strength indexes. Based on the theory of discontinuous medium, the uniaxial compression and uniaxial tensile tests of rocks were simulated, and the microscopic mechanical parameters of discrete elements of granite samples were determined based on the indoor macroscopic mechanical tests: effective modulus Et, compressive elastic modulus Ec, macro Poisson’s ratio μ, and uniaxial compressive strength σc. The results show that the parallel bond model has good simulation results for the uniaxial compression test, but the tensile strength and tensile–compression ratio were quite different from the experimental values. When the confining pressure is large, the calibrated parameter adaptability by uniaxial compression is poor. The reason for certain errors is a large resistance of the parallel bond model to particle rotation and the influence of normal stress on shear strength is not considered. The cementation model can be modified by adding coefficients based on laboratory test results.
Nuragic Working Tools Characterization with Corrosion Layer Determinations
Authors: Porcaro Marta , Depalmas Anna , Lins Sergio , Bulla Claudio , Pischedda Matteo , Brunetti Antonio
Published: May 2022

From the availability of metals to the technology and tools needed to transform them, roughly every civilization in the Mediterranean basin has a metalsmith story. Many of the objects produced by them share a few peculiar characteristics, usages, or even shapes. In this scenario, a class of objects that can be clustered by their usage, i.e., working tools, stands out from the crowd. For this study, a set of working tools from the Nuragic civilization (Sardinia, Italy) was researched with a non-destructive technique: X-ray Fluorescence (XRF). A quantification of the chemical species present in their alloy was obtained with the use of Monte Carlo simulations. The XRMC package, used for the simulations, managed for the first time to reproduce very complex corrosion layers and to thoroughly characterize them from a chemical perspective. The obtained results were discussed and compared to other results reported in the literature.
Numerical Simulation Study on Factors Influencing Anti-Explosion Performance of Steel Structure Protective Doors under Chemical Explosion Conditions
Authors: Wang Haiteng , Li Zhizhong , Wu Yingxiang , Shao Luzhong , Yao Meili , Liao Zhen , Tang Degao
Published: May 2022

To study the mechanical deformation characteristics and anti-explosion mechanisms of steel-structure protective doors under chemical explosion shock wave loads, numerical simulations of loads and door damage were carried out using the AUTODYN and LS-DYNA software based on model tuning with actual field test results. The finite element simulation results were compared with the test results to verify the accuracy of the simulation model and material parameters. A parametric analysis was carried out on the influencing factors of the anti-explosion performance of the beam–plate steel structure protective door under typical shock wave loads. The impact of the material strength and geometry of each part of the protective door on its anti-explosion performance was studied. The results showed that the protective door sustained a uniform shock wave load and that increasing the steel strength of the skeleton could significantly reduce the maximum response displacement of the protective door. The steel strength increase of the inner and outer panels had little or a negligible effect on the anti-explosion performance of the protective door. The geometric dimensions of different parts of the protective door had different effects on the anti-explosion performance. Increasing the skeleton height had the most significant effect on the anti-explosion performance. The skeleton’s I-steel flange thickness and the inner and outer panel thicknesses had less significant effects.