bluuebunny/crossref_metadata_2025 huggingface dataset:
Carbon Nitrogen Isotope Coupling of Soils and Seasonal Variation Characteristics in a Small Karst Watershed in Southern China
Authors: Liu Ya , Liu Ziqi , Xiong Kangning , Li Yuan , Lyu Xiaoxi , Cai Lulu
Published: February 2023

Carbon and nitrogen are among the most important biogenic elements in terrestrial ecosystems, and carbon and nitrogen stable isotopes (δ13C and δ15N) are often used to indicate the sources of carbon and nitrogen elements and turnover processes, and the study of C and N isotopes coupling can provide more precise indications. To this end, this study was conducted to investigate the effects of different land use types on soil organic carbon (SOC), soil organic nitrogen (SON) and the coupling relationship of C-N isotopes, as well as to reveal the seasonal variation characteristics of soil C and N. The results showed that SOC and SON contents of forest land were significantly higher than those of agricultural land and grassland. The soil C/N was significantly higher in the dry season than in the rainy season (p < 0.01), indicating that the decomposition rate of soil organic matter (SOM) was faster in the rainy season, which was not conducive to the accumulation of soil C. Soil δ13C and δ15N coupling showed seasonal characteristics: soil δ13C and δ15N did not have a good linear relationship in the rainy season, but showed a significant positive correlation in the dry season (r2 = 0.75, p < 0.05), indicating that there are differences in the soil C-N isotope fractionation coupling under the influence of climatic factors. This study provides a reference for regional land resource management as well as carbon and nitrogen cycle studies in karst areas.
A Life Cycle Assessment of Rice–Rice and Rice–Cowpea Cropping Systems in the West Coast of India
Authors: Paramesh Venkatesh , Kumar Parveen , Parajuli Ranjan , Francaviglia Rosa , Manohara Kallakeri Kannappa , Arunachalam Vadivel , Mayekar Trivesh , Toraskar Sulekha
Published: February 2023

Crop diversification is essential in lowland rice cropping systems to achieve sustainability, improve soil health, and as a climate-resilient practice to reduce greenhouse gas (GHG) emissions. A life cycle assessment (LCA) was conducted for the farms in the west-coast region of India to assess the environmental impact of the rice–rice and rice–cowpea cropping systems. The life cycle impact assessment (LCIA) was evaluated in a “cradle-to-gate” perspective. A higher energy consumption was found in the rice–rice system (32,673 vs. 18,197 MJ/ha), while the net energy output was higher in the rice–cowpea system (211,071 vs. 157,409 MJ/ha). Energy consumption was 44% lower in the rice–cowpea system, which was coupled with a higher energy efficiency (11.6 vs. 4.8), attributed to the lower energy consumption and the higher energy output. Further, the results indicated an energy saving potentialin the rice–cowpea system due to the higher use of renewable resources such as farmyard manure. Field emissions, fertilizer production, and fuel consumption were the major contributors to the greenhouse gas (GHG) emissions in both cropping systems. The total GHG emissions were 81% higher in the rice–rice system (13,894 ± 1329 kg CO2 eq./ha) than in the rice–cowpea system (7679 ± 719 kg CO2 eq./ha). The higher GHG emissions in the rice–rice system were largely due to the higher use of fertilizers, diesel fuel, and machinery. Hence, diversifying the winter rice with a cowpea crop and its large-scale adoption on the west coast of India would provide multiple benefits in decreasing the environmental impact and improving the energy efficiency to achieve sustainability and climate resilience in rice-based cropping systems.
Green Space Ecosystem Services and Value Evaluation of Three-Dimensional Roads for Sustainable Cities
Authors: Lee Eunjoung , Kim Gunwoo
Published: February 2023

The provision of green space as a result of three-dimensional roads plays a crucial role in maintaining the sustainability of the urban ecosystem. It does so by solving environmental problems and offering various ecosystem services to city residents. This study focuses on the park section of an expressway located between Bundang and Suseo in Seongnam city, South Korea, and quantifies the improvement in air quality and ecological value following the transformation of the road into green infrastructure. The goal is to determine the feasibility of sustainable green infrastructure for roads. The new park area on the road is approximately 83,000 sq. meters and there are approximately 3349 trees planted in the park. These trees can store 77.68 metric tons of carbon annually, isolate 13.21 metric tons of total carbon, remove 70.446 kg of air pollutants, avoid 112.8 cubic meters of emissions, and mitigate 31,983.90 cubic feet of emissions. The resulting economic value is approximately 874,494 dollars. Road green infrastructure conversion can be a useful solution to respond to environmental problems. To promote decision-making when developing policies, a process of pre-verification with quantified data of ecosystem services (example: air quality benefits, etc.) of trees using the i-Tree Eco program is required. In the execution stage, it is possible to understand the structure, function, and value of green spaces and prepare guidelines for tree selection, design alternatives, and evaluation as one of the management strategies for green spaces to improve the value of ecosystem services.
Soil Moisture Change Detection with Sentinel-1 SAR Image for Slow Onsetting Disasters: An Investigative Study Using Index Based Method
Authors: Bormudoi Arnob , Nagai Masahiko , Katiyar Vaibhav , Ichikawa Dorj , Eguchi Tsuyoshi
Published: February 2023

Understanding physical processes in nature, including the occurrence of slow-onset natural disasters such as droughts and landslides, requires knowledge of the change in soil moisture between two points in time. The study was conducted on a relatively bare soil, and the change in soil moisture was examined with an index called Normalized radar Backscatter soil Moisture Index (NBMI) using Sentinel-1 satellite data. Along with soil moisture measured with a probe on the ground, a study of correlation with satellite imagery was conducted using a Multiple Linear Regression (MLR) model. Furthermore, the Dubois model was used to predict soil moisture. Results have shown that NBMI on a logarithmic scale provides a good representation of soil moisture change with R2~86%. The MLR model showed a positive correlation of soil moisture with the co-polarized backscatter coefficient, but an opposite correlation with the surface roughness and angle of incidence. The results of the Dubois model showed poor correlation of 44.37% and higher RMSE error of 17.1, demonstrating the need for detailed and accurate measurement of surface roughness as a prerequisite for simulating the model. Of the three approaches, index-based measurement has been shown to be the most rapid for understanding soil moisture change and has the potential to be used for understanding some mechanisms of natural disasters under similar soil conditions.
Sustainable Development of Rural Areas in Poland since 2004 in the Light of Sustainability Indicators
Authors: Widomski Marcin K. , Musz-Pomorska Anna
Published: February 2023

Sustainable development of a region requires sustainability of its rural parts, as a source of supplies and resources for the urbanized regions. The current climate changes, loss of biodiversity, limited resources, depopulation, deterioration of economic conditions or even poverty may limit the sustainable development of rural populations. This paper presents the study concerning assessment of sustainable development of rural areas in Poland since 2004, the date of Poland entrance to the European Union, in light of the selected Sustainable Development Indicators. The assessment was based on the set of 38 indicators covering environmental, social and economic pillars of sustainability. The results of this study indicate the significant progress in some aspects of rural development in Poland since 2004. However, several serious limits for rural sustainability were identified, including limited access to basic services including sanitation, anthropopressure on the natural environment, limited access to clear and renewable energy, depopulation, ageing, unfavorable economic conditions and relatively low productivity of agriculture.
The Effects of Urbanisation on Green Growth within Sustainable Development Goals
Authors: Kwilinski Aleksy , Lyulyov Oleksii , Pimonenko Tetyana
Published: February 2023

The Green Deal policy and Sustainable Development Goals require that the economic development of a country should be reoriented towards ‘green‘ economic development. Currently, the globalisation and intensification of production boosts urbanisation in many countries, which may stimulate economic growth and improve citizen well-being, but may also lead to excessive consumption of resources and negative environmental impacts. Against the backdrop of these challenges, it is expedient to estimate the effects of urbanisation on the green growth of a country and define the relevant changes and instruments for achieving green growth in a country in view of urbanisation. The research covers the EU countries and Ukraine (as an official candidate for European Union membership) in the period of 2005–2020. Applying the Global Malmquist–Luenberger productivity index (to estimate green economic growth); a fixed and random effects model, GMM modelling (to evaluate the impact of urbanisation on green economic growth), this study aimed to contribute to the theoretical framework of green economic growth by extending input and undesirable output parameters of a country’s productivity. The findings revealed that, in 2020, as compared to 2005, green economic growth went into a decline in all countries analysed, this decline stemmed from accelerated urbanisation. However, industrial structure and research and development appeared to be conducive to green economic growth, which justifies the idea that countries should focus on implementing structural reforms for the technological modernisation of infrastructure and industrial complexes to dispose of the shortcomings caused by urbanisation. To compensate for this negative impact, the findings of this research prompt a set of policy implications concerning dissemination of the green knowledge and technologies, green project implementation, reinforcement of incentive instruments and achievement of a synergistic balance of economic and ecological targets underlying the SDGs.
From Garden City to 15-Minute City: A Historical Perspective and Critical Assessment
Authors: Khavarian-Garmsir Amir Reza , Sharifi Ayyoob , Hajian Hossein Abadi Mohammad , Moradi Zahra
Published: February 2023

The 15-minute city concept was introduced as a post-COVID strategy to support more sustainable recovery from the pandemic and develop complete, climate-sensitive, and resilient neighborhoods. This review examines key neighborhood planning movements to identify the origins of the 15-minute city concept. These include the garden city, neighborhood unit plan, modernist urbanism, post-modern urbanism, and eco-urbanism, which have emerged since the late 19th century. The results of the study show that the concept of the 15-minute city has ten basic characteristics: proximity, density, diversity, mixed-use, modularity, adaptability, flexibility, human-scale design, connectivity, and digitalization. The concept has been successful in advancing theoretical debates on sustainable urbanism. However, some criticisms of past planning movements also apply to the 15-minute city. Similar to the neighborhood unit and modernist urbanism, the concept follows a philosophy of physical determinism, setting goals without specifying how or by what means they will be achieved. At this point, one can only speculate about the future of the concept. A more detailed study of the real-world applications of the concept is needed before one can thoroughly discuss its strengths and weaknesses.
Role of Traditional Agroforestry Systems in Climate Change Mitigation through Carbon Sequestration: An Investigation from the Semi-Arid Region of Pakistan
Authors: Yasin Ghulam , Nawaz Muhammad Farrakh , Zubair Muhammad , Azhar Muhammad Farooq , Mohsin Gilani Matoor , Ashraf Muhammad Nadeem , Qin Anzhen , Ur Rahman Shafeeq
Published: February 2023

Several agroforestry systems prevail in different agro-ecological zones of Pakistan, and cover a remarkable area of 19.3 million hectares. They not only play an important role in slowing down CO2 emissions, but also contribute to mitigating climate change. However, in many regions, the relevant effect of agroforestry systems on overall carbon (C) stock and their reliance on various factors are quite unidentified. This study was planned to assess the biomass accumulation and C stocks of different commonly practiced agroforestry systems (boundary, bund, scattered, agri-horticulture) and their constituent land use types (tree + cropland) through a non-destructive approach (allometric equations) in a semi-arid region of Punjab, Pakistan. The results showed that the highest plant biomass (87.12 t ha−1) increased by 46%, 17%, 78%, and 339%, and C stock (42.77 t ha−1) increased by 49.51%, 20%, 82%, and 361% in the boundary planting system compared to the bund, scattered, agri-horti and sole cropland, respectively. The soil organic carbon (SOC) stock at all three depths, 0–15 cm, 15–30 cm & 30–45 cm, was found in the following order: boundary planting system > bund planting system > agri-horti system > scattered planting system > agricultural system, with a maximum in the boundary planting system and minimum in the sole cropping system at all three depths. Overall, the total C stock of the ecosystem’s vegetation + soil C (0–30 cm) in the forested area was 275 t ha−1, equating to 37 t ha−1 in the agricultural system alone. Our results highlighted that agroforestry systems have the highest potential for C sequestration. We suggest that research and investment in agroforestry systems can be a successful way for Pakistan to achieve some of its climate change mitigation goals.
Spatio-Temporal Analysis of Cultivated Land from 2010 to 2020 in Long’an County, Karst Region, China
Authors: Dong Jianhui , Yun Wenju , Wu Kening , Li Shaoshuai , Liu Bingrui , Lu Qiaoyuan
Published: February 2023

Spatio-temporal changes in cultivated land have a profound impact on food security and sustainable development. However, existing studies on spatio-temporal changes in cultivated land mostly focus on single factors, for instance quantity, quality and ecology, that cannot comprehensively reflect the changes in total production capacity and the sustainability of cultivated land. This study aims to construct a comprehensive analysis approach and to provide a reference basis for a comprehensive analysis of the extent of changes in overall cultivated land food-production capacity and the formulation of cultivated land conservation-related policies. This comprehensive analysis method constructed from three dimensions: quantity, production capacity and ecology, fully reflects the changes in the total amount, structure, rate of change, spatial distribution, quality, total production capacity and sustainability of cultivated land. The results from the application of this approach to Long’an County, Guangxi Province, China demonstrate that: (a) from 2010 to 2020, the total amount of cultivated land in Long’an County decreased sharply by 30.83%, accounted for mainly by the conversion into orchards, forest land and other garden land; (b) the quality of cultivated land improved by 2.71% on average, mostly in relation to natural factors; (c) the total food-production capacity of cultivated land decreased by 28.96% on average, mainly due to the decrease in the area of cultivated land; (d) both the ecological grade and the sustainability of cultivated land decreased slightly; (e) the barycenter of cultivated land migrated 3.3 km to the ecologically sensitive areas in the west, and the patch size of cultivated land decreased from an average of 2.60 hectares/pc in 2010 to that of 1.34 hectares/pc in 2020, suggesting increased fragmentation of cultivated land; and (f) the patch regularity of cultivated land decreased from 2.08 in 2010 to 1.76 in 2020, showing improved patch regularity and slightly better adaptability to mechanization. There were two main reasons for the lower, total food production capacity in Long’an County: first, the low comparative income of grain cultivation, because of which farmers spontaneously adjusted the agricultural cultivation structure to pursue high returns; and second, the lack of targeted government policies to protect cultivated land. In general, this comprehensive analysis method is applicable to other provinces in China or other regions abroad to provide a reference basis for a comprehensive understanding of changes in the food production capacity of cultivated land and the formulation of policies on cultivated land protection.
Venezuelan Migration, COVID-19 and Food (in)Security in Urban Areas of Ecuador
Authors: Milán Taymi , Martens Cheryl
Published: February 2023

The forced migration of nearly 6 million Venezuelans is a global issue that is transforming urban contexts, particularly in Latin America. Ecuador is the third main recipient country of displaced Venezuelans. The lack of State migration policies and the deteriorating economic situation throughout the region have had significant impacts on migrants. While food security and migration have been studied extensively in Latin America, their intersection remains under-explored. Through a systematic review and focus group research, this exploratory study analyzes the food security conditions of Venezuelans in Ecuador and the impacts of the COVID-19 pandemic on the levels of food insecurity using an intersectional approach. Quantitative, systematic review results demonstrate that demands for food assistance outweighed the planning and provisions supplied by both state and non-state actors. Focus groups results support the findings from the systematic review and demonstrate that in the medium-sized port cities of Manta and Machala, food demands during the pandemic lockdown measures were met through the direct food supply and resilience strategies, including the securing of personal loans and bartering. In contrast, in the cities of Quito and Huaquillas, strict enforcement of COVID-19 lockdown measures, reduced access to work and systematic food access and increased reliance on food assistance from non-governmental actors. This study also found that the impacts of food (in)security in the context of COVID-19 disproportionately affected women in all cities, as they offered their food rations to meet the needs of their children, grandchildren, or other dependents.
Intraobserver and Interobserver Agreement between Six Radiologists Describing mpMRI Features of Prostate Cancer Using a PI-RADS 2.1 Structured Reporting Scheme
Authors: Jóźwiak Rafał , Sobecki Piotr , Lorenc Tomasz
Published: February 2023

Clinical practice has revealed ambiguities in PI-RADS v2.1 scoring, but a limited number of studies are available that validate the interreader and intrareader reproducibility of the mpMRI PI-RADS lexicon. We decomposed the PI-RADS rules into a set of common data elements to evaluate the inter- and intraobserver agreement in assessing the individual features included in the PI-RADS lexicon. Six radiologists (three highly experienced, three less experienced) in two sessions independently read thirty-two lesions in the peripheral and transition zone using the structured reporting tool, blinded to clinical MRI indication. The highest agreement between radiologists was observed for the abnormality detection, the evaluation of the type of signal intensity, and the characteristic of benign prostatic hyperplasia. Moderate agreement was reported for dynamic contrast-enhanced images. This resulted in a decrease in abnormality detection (PA = 76.5%) and enhancement indication (PA = 77.3%). The lowest agreement was observed for highly subjective features: shape, signal intensity level, and type of lesion margins. The results indicate the limitations of the PI-RADS v2.1 lexicon in relation to interreader and intrareader reproducibility. We have demonstrated that it is possible to develop structured reporting systems standardized according to the PI-RADS lexicon.
Higher Dietary Vitamin D Intake Influences the Lipid Profile and hs-CRP Concentrations: Cross-Sectional Assessment Based on The National Health and Nutrition Examination Survey
Authors: Hariri Zahra , Kord-Varkaneh Hamed , Alyahya Noura , Prabahar Kousalya , Găman Mihnea-Alexandru , Abu-Zaid Ahmed
Published: February 2023

Background. An unanswered question in the field of nutrition is whether there is an association between vitamin D intake and the lipid profile in adults. We conducted this cross-sectional study in order to investigate the impact of vitamin D intake on the lipid profile of adults in the context of the 2017–2018 National Health and Nutrition Examination Survey (NHANES). Methods. Serum lipids and high-sensitivity C-reactive protein (hs-CRP) concentrations and the Vitamin D intake in 2588 people aged 19 to 70 years was collected using laboratory analysis and 24-h recall, respectively. The one-way ANOVA test was used to compare quantitative variables and the chi-squared test was used to compare qualitative ones. Multivariate logistic regression for three models was performed to assess the odds ratio (OR) of high total cholesterol (TC) (>200 mg/dL), triglycerides (TG) (>150 mg/dL), low-density lipoprotein cholesterol (LDL-C) (>115 mg/dL), high-density lipoprotein cholesterol (HDL-C) (<40 mg/dL) and hs-CRP (>1 mg/l) based on the tertiles of dietary vitamin D (D2 + D3) intake. Results. After adjusting for age, sex, race, body mass index, serum 25-hydroxyvitamin D2, alcohol intake, energy intake, protein intake, carbohydrate intake, fiber intake and fat intake, individuals in the tertile with the highest versus lowest vitamin D intake (>1 mcg/day vs. <0.10 mcg/day) had lower odds of displaying elevated TC, LDL-C and hs-CRP concentrations (OR 0.57; CI: 0.37 to 0.88; P-trend: 0.045, OR 0.59; CI: 0.34 to 1.01; P-trend: 0.025 and OR 0.67; CI: 0.45 to 0.99; P-trend: 0.048, respectively). Based on the results of the logistic regression, no correlation between vitamin D intake and changes in TG or HDL-C values was noted. Conclusions. Our cross-sectional study indicates that higher dietary vitamin D (D2 + D3) intake is associated with lower TC, LDL-C and hs-CRP levels. No relationship between dietary vitamin D intake and TG or HDL-C values was detected. Further large-scale randomized trials are needed to evaluate the actual association between dietary vitamin D intake and the lipid profile.
SARS-CoV-2 Infection and the Male Reproductive System: A Brief Review
Authors: Rago Vittoria , Perri Anna
Published: February 2023

Many studies have suggested that SARS-CoV-2, directly or indirectly, can affect the male reproductive system, although the underlined mechanisms have not been completely elucidated yet. The purpose of this review is to provide a summary of the current data concerning the impact of SARS-CoV-2 infection on the male urogenital tract, with a particular emphasis on the testes and male fertility. The main data regarding the morphological alterations in the testes emerged from autoptic studies that revealed interstitial congestion, micro thrombosis, reduction of Sertoli, Leydig, and germinal cells, infiltrated immune cells, and atrophic seminiferous tubules consistent with orchitis. Furthermore, men with severe infection exhibit sperm parameter alterations, together with abnormalities of the hypothalamic–pituitary–testis axis, strongly suggesting that SARS-CoV-2 could increase the risk of male infertility. However, despite the inadequate number of longitudinal studies, spermatogenesis and sex hormone imbalance seem to improve after infection resolution. The yet unresolved question is whether the virus acts in a direct or/and indirect manner, as discordant data related to its presence in the testis and semen have been reported. Regardless of the direct effect, it has been postulated that the cytokine storm and the related local and systemic inflammation could strongly contribute to the onset of testis dysfunction, leading to male infertility. Therefore, multicentric and longitudinal studies involving a large number of patients are needed to understand the real impact of SARS-CoV-2 infection on male reproduction.
N-(((1S,5R)-6,6-Dimethylbicyclo[3.1.1]hept-2-en-2-yl)methyl)-3-((1R,5S)-6,6-dimethylbicyclo[3.1.1]hept-2-ene/ane-2-carboxamido)-N,N-dimethylpropan-1-aminium Bromide
Authors: Gilfanov Ilmir R. , Pavelyev Roman S. , Nikitina Liliya E. , Frolova Larisa L. , Popov Alexey V. , Rakhmatullin Ilfat Z. , Klochkov Vladimir V. , Lisovskaya Svetlana A. , Trizna Elena Yu. , Grishaev Denis Yu. , Kayumov Airat R.
Published: February 2023

The synthesis of the title compounds was performed from (-)-cis-myrtanic and (-)-myrtenic acids. The compounds obtained were characterized using 1H- and 13C-NMR, IR, and high-resolution mass spectrometry. Despite the presence of quaternary ammonium moiety, both compounds had moderate antimicrobial activity with a MIC of 128 µg/mL on S. aureus and 512 µg/mL on E. coli. The antifungal activity was low on Candida isolates, while also comparable with conventional antimycotic (Fluconazole) on filamentous fungi. These data suggest that two bulky bicyclic terpene fragments apparently both increase lipophilicity and close the quaternary ammonium moiety located in the center of molecules and thus drastically decrease the antimicrobial potential of bipharmacophore.
Electric Cable Construction Parameter and Its Potential to Foresee the Cable Fire Properties
Authors: Kaczorek-Chrobak Katarzyna , Fangrat Jadwiga
Published: February 2023

A cable parameter related to the volume of effective non-combustible content, Ω, is proposed, which depends on the ratio of non-metallic, non-combustible component volume to non-metallic, combustible component volume, and the effective area of heat transfer within the cable during the combustion process. The correctness of the proposed cable parameter for circular cables is confirmed by tests and the determination of Spearman’s correlation. High Spearman’s correlation factors (close to −1) were obtained for total heat release and total smoke production as a function of the Ω cable parameter. The Ω cable parameter might be used in selecting cable samples for large geometric-scale fire testing within the same cable family.
A Gradient Microstructure Improves the Barrier Properties of Flake-Filled Composite Films: A Computational Study
Authors: Papathanasiou Thanasis D. , Diakonikolis Michalis , Tsiantis Andreas
Published: February 2023

Composite films of a graded miscrostructure hold the promise of achieving optimal use of the filler material, resulting in composites with improved and application-taylored properties. In the context of barrier materials in which the reinforcing phase comes in the form of flakes or platellets, concentrating the filler particles in certain critical regions is thought to achieve economy in filler usage while ensuring superior barrier performance. The objective of the present article is to quantitatively test this hypothesis and provide guidelines on the expected barrier improvement. A model is developed, according to which a graded miscostructure in a composite film offers a quantitative improvement over an equivalent homogeneous microstructure; this improvement is quantified using a coefficient β, which depends on the form of the graded miscrostructure, specifically the distribution of the number-density of the filler particles across the film. It is shown that β=1 for a uniform microstructure and β>1 for a graded one, indicating that a graded miscrostructure will indeed result in improved barrier properties. Analytical expressions for β are developed for certain typical distributions; for a linear filler distribution, it is shown that β=4/3. This model is tested against detailed multi-particle simulations and is found to be in excellent agreement with computational results.
The Utilization of a Coupled Electro-Thermal-Mechanical Model of High-Voltage Electric Pulse on Rock Fracture
Authors: Feng Weikang , Rao Pingping , Nimbalkar Sanjay , Chen Qingsheng , Cui Jifei , Ouyang Peihao
Published: February 2023

Our research proposes a unique coupled electro-thermal-mechanical model that takes electric breakdown and heterogeneity into account to show the mechanism of rock fracturing under high-voltage electropulses. Using finite element numerical software, the process of high voltage electrical pulse injection into the rock interior for breakdown is described, and the formation law of plasma channels during the electrical breakdown process is comprehensively analyzed in conjunction with the conductor particles present within the rock. On the basis of electrical, thermal, and mechanical theories, a coupled multi-physical field numerical model of rock failure under the action of high-voltage electrical pulses is developed, and a random distribution model is utilized to simulate the potential occurrence of conductor particles in the rock. Innovative numerical model indicates plasma channel creation in the rock-crushing process. Prior to the formation of the plasma channel, the temperature and stress are approximately 103 k and 10−2 MPa, respectively. Once the plasma channel is formed, the temperature and stress increase abruptly in a short time, with the temperature reaching 104 k and the stress reaching 103 MPa or higher. In addition, it is revealed that the breakdown field strength is the essential factor in plasma channel creation. The heterogeneity of the particles within the rock and the fluctuation in electrode settings are also significant variables influencing the creation of channels. The presented model contributes to a better understanding of the mechanism of rock fragmentation during high-voltage electrical pulses, which has substantial implications for oil exploration and mineral extraction.
The Mechanical Characteristics of High-Strength Self-Compacting Concrete with Toughening Materials Based on Digital Image Correlation Technology
Authors: Cheng Zhiqing , Zhao Hong , Long Guangcheng , Yang Kai , Chen Mengting , Wu Zhi
Published: February 2023

Brittle fracture is a typical mechanical characteristic of high-strength self-compacting concrete, and the research on its toughening modification remains the highlight in the engineering field. To understand the effect of toughening materials (including polymer latex powders, rubber particles, and polyethylene fibers) on the mechanical behavior of C80 high-strength self-compacting concrete under static loading, the failure mode, mechanical strength, strain field, and crack opening displacement (COD) of prepared high-strength self-compacting concrete under compressive, splitting, and flexural loads were studied based on digital image technology (DIC). The corresponding mechanism is also discussed. The results show that the hybrid of polymer latex powders, rubber particles, and polyethylene fibers can increase the crack path and inhibit the development of macrocracks in concrete, thus turning the fracture behavior of concrete from brittle to ductile. The addition of toughening materials reduced the compressive and flexural strengths of high-strength self-compacting concrete, but it increased the splitting strength. DIC showed that the incorporation of toughening materials promoted the redistribution of strain and reduced the degree of strain concentration in high-strength self-compacting concrete. The evolution of COD in high-strength self-compacting concrete can be divided into two stages, including the linear growth stage and the plastic yield stage. The linear growth stage can be extended by incorporating toughening materials. The COD and energy absorption capacity of concrete were enhanced with the addition of toughening materials, and the best enhancement was observed with the hybrid of polymer latex powders, rubber particles, and polyethylene fibers. Overall, this research provides a reference for exploring effective technical measures to improve the toughness of high-strength self-compacting concrete.
Synthesis of Blue Gahnite (ZnAl2O4:Co, Nd): A Cost-Effective Method for Producing Solar-Reflective Pigments for Cool Coatings
Authors: Primo Julia de Oliveira , Horsth Dienifer F. L. , Balaba Nayara , Umek Polona , Anaissi Fauze J. , Bittencourt Carla
Published: February 2023

Developing strategies for the green synthesis of novel materials, such as pigments for protection from solar radiation, is a fundamental research subject in material science to mitigate the heat island effect. Within this perspective, the current study reports on the synthesis of blue pigments of ZnAl2O4:M (M = Co2+ and Co2+/Nd3+) using recycled metallic aluminum (discarded can seal) with reflective properties of Near-infrared radiation. The pigments were characterized by XRD, SEM, XPS, UV-Vis, NIR diffuse reflectance spectroscopy, and CIE-1976 L*a*b* color measurements. The wettability of the coatings containing the synthesized pigments was also evaluated. The structural characterization showed that the pigments present the Gahnite crystalline phase. Colorimetric measurements obtained by the CIEL*a*b* method show values correlated to blue pigments attributed to Co2+ ions in tetrahedral sites. The pigments exhibit high near-infrared solar reflectance (with R% ≥ 60%), with an enhancement of nearly 20% for the pigment-containing neodymium when applied in white paint, indicating that the prepared compounds have the potential to be energy-saving color pigments for coatings.
Synthesis and Characterization of SPIONs Encapsulating Polydopamine Nanoparticles and Their Test for Aqueous Cu2+ Ion Removal
Authors: Siciliano Giulia , Turco Antonio , Monteduro Anna Grazia , Fanizza Elisabetta , Quarta Alessandra , Comparelli Roberto , Primiceri Elisabetta , Curri M. Lucia , Depalo Nicoletta , Maruccio Giuseppe
Published: February 2023

The removal of pollutants, such as heavy metals, aromatic compounds, dyes, pesticides and pharmaceuticals, from water is still an open challenge. Many methods have been developed and exploited for the purification of water from contaminants, including photocatalytic degradation, biological treatment, adsorption and chemical precipitation. Absorption-based techniques are still considered among the most efficient and commonly used approaches thanks to their operational simplicity. In recent years, polydopamine-coated magnetic nanoparticles have emerged for the uptake of heavy metals in water treatment, since they combine specific affinity towards pollutants and magnetic separation capacity. In this context, this work focuses on the synthesis of polydopamine (PDA)-coated Super Paramagnetic Iron Oxide Nanoparticles (PDA@SPIONs) as adsorbents for Cu2+ ions, designed to serve as functional nanostructures for the removal of Cu2+ from water by applying a magnetic field. The synthetic parameters, including the amount of SPIONs and PDA, were thoroughly investigated to define their effects on the nanostructure features and properties. Subsequently, the ability of the magnetic nanostructures to bind metal ions was assessed on Cu2+-containing solutions. A systematic investigation of the prepared functional nanostructures was carried out by means of complementary spectroscopic, morphological and magnetic techniques. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) measurements were performed in order to estimate the Cu2+ binding ability. The overall results indicate that these nanostructures hold great promise for future bioremediation applications.
A Facile and Rapid Strategy for Quantifying PCBs in Cereals Based on Dispersive Solid-Phase Extraction and Gas Chromatography–Mass Spectrometry: A Reference for Safety Concerns in Sustainable Textiles
Authors: Liu Tengfei , Song Ying , Wang Xiangyun , Shi Linlin , Dong Minghui
Published: February 2023

Cereals and their derivative products such as starch and cyclodextrin are significant natural materials for sustainable textile processing (e.g., sizing, dispersing, etc.). However, the contamination of cereals with polychlorinated biphenyls (PCBs) is often neglected, which has led to increasing concerns due to the adverse effects on end users. Therefore, monitoring PCBs in cereals is of great importance in preventing health risks. However, high starch, protein, and fat contents make cereals a complicated matrix and can challenge the analysis of PCBs in cereals. This work describes a facile and rapid strategy for quantifying 18 PCBs in cereals that included corn, wheat, and rice through dispersive solid-phase extraction and gas chromatography with mass spectrometry. Importantly, this was the first time that carboxyl-modified, multi-walled carbon nanotubes were incorporated in the detection of PCBs in cereals. The influences of several parameters on the extraction and clean-up efficiency were investigated; these included the type and volume of extraction solvent, sonication time, and the type and dosage of the adsorbent. The matrix effects on quantification were also evaluated. This approach exhibited a better clean-up performance. All the analytes showed weak matrix effects, and thus a solvent standard plot could be prepared for their quantification. Spiking experiments in the selected matrices at three concentration levels from 0.5 to 10 μg/kg resulted in satisfactory recoveries that ranged from 79.2% to 110.5% with relative standard deviations (RSDs; n = 6) less than 10.3%. The limits of detection (LODs) and quantification (LOQs) ranged from 0.04 to 0.1 μg/kg and 0.1 to 0.4 μg/kg, respectively. The practical application of this method was investigated by analyzing actual cereal samples, which demonstrated that the proposed approach was a facile and efficient strategy for PCB determination and provided a reference for the safety evaluation of sustainable textiles. The method also could be generalized to other troublesome samples for testing of multiple PCBs.
Experimental Analysis and Establishment of Strength Attenuation Model of POM Fiber Reinforced Geopolymeric Recycled Concrete under Freeze-Thaw Cycles
Authors: Shi Xiaoshuang , Wang Xiaoqi , Wang Qingyuan , Zhang Tao , Yang Fuhua , Xu Yufei , Zhan Jinsheng
Published: February 2023

Geopolymeric recycled concrete (GRC) is a new low-carbon building material that uses both construction and industrial solid waste to replace natural aggregate and cement. GRC is similar to geopolymeric concrete (GPC) in that it has good mechanical properties but needs to be improved in terms of frost resistance. Previous studies have shown that polyoxymethylene fiber (POM fiber) can improve the shrinkage and durability of concrete and is superior to other commonly used fibers. Therefore, this paper explores adding POM fiber to GRC to improve its frost resistance. In this paper, the influence of different volumes and lengths of POM fiber on the frost resistance of geopolymeric recycled concrete (PRGRC) is studied. By measuring the changes in mass loss rate, relative dynamic elastic modulus, and compressive strength of PRGRC under different cycles, the improvement effect of POM fiber on the freeze-thaw damage of GRC is analyzed, and the strength attenuation model of PRGRC is established. The results show that the increase in POM fiber content can effectively slow down the mass loss of PRGRC in the freeze-thaw cycles, the reduction rate of relative dynamic elastic modulus, and the reduction rate of compressive strength. This shows that POM fiber can effectively improve the frost resistance of PRGRC, and the effect of 6 mm POM fiber on the freeze-thaw damage of PRGRC is better than 12 mm POM fiber. According to the test results, the existing strength attenuation model is further modified, the attenuation model of PRGRC compressive strength under the freeze-thaw cycle is obtained, and the model fitting effect is good. The strengthening mechanism of POM fiber is explained by the structural relationship between POM fiber and concrete matrix in the SEM micrograph of PRGRC. The research results provide a scientific basis for the applicability of POM fiber in geopolymeric cementitious materials and improving the frost resistance of PRGRC.
Properties Evaluations of Topology Optimized Functionally Graded Lattice Structures Fabricated by Selective Laser Melting
Authors: Xu Yangli , Han Guangyao , Huang Guoqin , Li Tingting , Xia Jiaxu , Guo Donghai
Published: February 2023

Owning to their lightweight characteristic and high performance, functionally graded lattice structures (FGLSs) show great potential in orthopedics, automotive industries and aerospace applications. Here, two types of uniform lattice structures (ULSs) with RD = 0.50 and 0.20, and two types of FGLSs with RD = 0.30–0.50 and RD = 0.20–0.40, were designed by topology optimization and fabricated by SLM technology. Subsequently, their surface morphology, compressive deformation behavior and energy absorption abilities were evaluated by use of the finite element method (FEM) and compression tests. From these results, both elastic modulus and yield strength of specimens decreased with the lowering of the RD value. ULSs had a uniform deformation behavior with bending and bulking of struts, while FGLSs presented a mixed deformation behavior of different layers. Additionally, the energy absorption capability (Wv) of specimens was proportional to the RD value. When the value of RD increased from 0.20 to 0.50, the Wv of specimens increased from 0.3657 to 1.7469 MJ/m3. Furthermore, mathematical models were established successfully to predict the mechanical properties of FGLSs with percentage deviations < 10%. This work provides a comprehensive understanding regarding how to design and manufacture FGLSs with the properties desired for satisfying the demand of different application scenarios.
Influence of Surface-Modified Montmorillonite Clays on the Properties of Elastomeric Thin Layer Nanocomposites
Authors: Olszewski Adam , Ławniczak Aleksandra , Kosmela Paulina , Strąkowski Marcin , Mielewczyk-Gryń Aleksandra , Hejna Aleksander , Piszczyk Łukasz
Published: February 2023

In recent years, polyurethane nanocomposites have attracted more attention due to the massive demand for materials with increasingly exceptional mechanical, optical, electrical, and thermal properties. As nanofillers have a high surface area, the interaction between the nanofiller and the polymer matrix is an essential issue for these materials. The main aim of this study is to validate the impact of the montmorillonite nanofiller (MMT) surface structure on the properties of polyurethane thin-film nanocomposites. Despite the interest in polyurethane–montmorillonite clay nanocomposites, only a few studies have explored the impact of montmorillonite surface modification on polyurethane’s material properties. For this reason, four types of polyurethane nanocomposites with up to 3% content of MMT were manufactured using the prepolymer method. The impact of montmorillonites on nanocomposites properties was tested by thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), contact angle measurement, X-ray diffraction (XRD), and optical coherence tomography (OCT). The results showed that chemical and physical interactions between the polymer matrix and functional groups on the montmorillonite surface have a considerable impact on the final properties of the materials. It was noticed that the addition of MMT changed the thermal decomposition process, increased T2% by at least 14 °C, changed the hydrophilicity of the materials, and increased the glass transition temperature. These findings have underlined the importance of montmorillonite surface structure and interactions between nanocomposite phases for the final properties of nanocomposites.
Study of Residual Stresses and Austenite Gradients in the Surface after Hard Turning as a Function of Flank Wear and Cutting Speed
Authors: Mičietová Anna , Čilliková Mária , Čep Róbert , Neslušan Miroslav , Ganev Nikolaj
Published: February 2023

This paper investigates the influence of cutting speed and flank wear on the depth profile of residual stresses, as well as the fraction of retained austenite after hard turning of quenched bearing steel 100Cr6. Residual stress and retained austenite profiles were studied for the white layer, heat-affected zone thickness, and XRD sensing depth. It was found that the influence of flank wear on the white layer and heat-affected zone thickness predominates. On the other hand, residual stresses are affected the cutting speed and the superimposing contribution of flank wear. Moreover, these aspects also alter microhardness in the affected regions. The study also demonstrates that information concerning residual stresses and the austenite fraction is integrated into the white layer, and the heat-affected zone in the surface is produced by the insert of low flank wear since the XRD sensing depth is more than the thickness of the white layer. On the other hand, the pure contribution of the white layer or the heat-affected zone to residual stress and the austenite fraction can be investigated when the affected surface region is thick enough.
Fatigue Crack Growth Rate Description of RF-Plasma-Sprayed Refractory Metals and Alloys
Authors: Kovarik Ondrej , Cizek Jan , Klecka Jakub
Published: February 2023

A fitting method capable of describing the fatigue crack growth rate (FCGR) data in all stages of crack propagation by a simple Forman-style analytical formula was developed. To demonstrate its robustness, this method was used to quantify the fracture behavior of RF-plasma-sprayed W, Mo, W-Mo composite, and four selected Ni-based tungsten heavy alloys (WHA). The fitted FCGR parameters categorized the studied materials into two distinct sets. W, Mo, and W-Mo composite deposits made from inherently brittle refractory metals that contained a range of defects inherent to plasma spray process represented the first class. This class was characterized by low fracture toughness and a relatively wide range of fatigue crack growth thresholds. The second class of materials was represented by WHA. Here, the deposit defects were suppressed by liquid state diffusion that formed a typical WHA structure consisting of a Ni-rich matrix and large spherical W reinforcement particles. The WHA generally showed higher fatigue crack growth thresholds, but differed in fracture toughness values based on the W particle concentrations. The obtained fracture mechanical data represent a reference dataset of plasma-sprayed refractory materials, and their classification into groups clearly demonstrates the capabilities of the developed method to capture a wide range of different types of FCGR behavior.
Effect of Grain Size on the Tribological Behavior of CoCrFeMnNi High Entropy Alloy
Authors: Wang Ying , Li Dong , Yang Junsheng , Jin Junsong , Zhang Mao , Wang Xinyun , Li Bin , Hu Zhigang , Gong Pan
Published: February 2023

The effect and mechanism of grain sizes on the tribological behavior of CoCrFeMnNi high entropy alloy (HEA) were studied by friction experiments and wear morphology analysis. Under normal low load and low sliding speed, the primary wear mechanism of the HEA samples is adhesive wear. With the increase in sliding speed, the wear mechanisms of the samples are adhesive wear and oxidation wear. The oxide layer formed under the action of friction heat of the coarse grain (CG) sample is easy to break due to the softening of the CG. With the increase of normal load and sliding speed, the wear mechanisms of the HEA samples are mainly adhesive wear, oxidation wear, and plastic deformation. The oxide layer of CG sample has many cracks, and the worn surface also has plastic deformation, which leads to the increase of friction coefficient and specific wear rate and the decrease of wear resistance. Therefore, the fine grain size HEA sample has better wear resistance than the CG sample due to its high surface strength.