bluuebunny/crossref_metadata_2025 huggingface dataset:
Environmentally Friendly and Broad–Spectrum Antibacterial Poly(hexamethylene guanidine)–Modified Polypropylene and Its Antifouling Application
Authors: Qiu Biwei , Wang Meng , Yu Wenwen , Li Shouhu , Zhang Wenyang , Wang Shuting , Shi Jiangao
Published: March 2023

Biological fouling is one of the main reasons that limits the application of traditional polypropylene (PP) fishing nets in aquaculture. Here, a new environmentally friendly and broad–spectrum antibacterial agent called cationic poly(hexamethylene guanidine) (PHMG) was grafted onto PP molecular chains via permanent chemical bonding to inhibit the biological fouling. The antibacterial monofilaments were obtained by blending different contents of PP–g–PHMG with PP by melt spinning. FTIR results found PHMG to be stably present in the mixed monofilaments after high–temperature melt spinning molding. The crystallinity, relaxation behavior, mechanical properties, water absorptivity, and antibacterial and antifouling efficiencies of the PP–g–PHMG/PP blends were strongly dependent on PP–g–PHMG. The crystallinity increased with increasing PP–g–PHMG content. Adding PP–g–PHMG improved the breaking strength, knotting strength, and elongation at the break for all ratios of PP–g–PHMG/PP blends. However, the water absorption caused by PHMG is low, ranging between 2.48% and 3.45% for the PP–g–PHMG/PP monofilaments. The monofilaments showed excellent nonleaching antimicrobial activities against Staphylococcus aureus and Escherichia coli. The electrostatic adsorption of the negatively charged bacteria and the destruction of their cell membrane allowed the growth inhibition to reach 99.69% with a PP–g–PHMG content of 40%. The marine fish farming experiment also showed a long–term antifouling effect.
Mechanical Properties and Synergistic Interfacial Interactions of ZnO Nanorod-Reinforced Polyamide–Imide Composites
Authors: Kesler Dallas , Ariyawansa Bhanuka P. , Rathnayake Hemali
Published: March 2023

Metal oxide nanoparticle -reinforced polymers have received considerable attention due to their favorable mechanical properties compared to neat materials. However, the effect of nanoscale reinforcements of the interface on the composites’ mechanical properties has not been investigated in-depth to reach their optimal performance in structural applications. Aiming at revealing the effect of synergistic interfacial interactions on the mechanical properties of polymer composites, using a nanoscale reinforcement, herein, a series of zinc oxide nanorod-reinforced polyamide–imide (PAI)/ZnO) composites were fabricated and their mechanical properties and viscoelastic responses were investigated. The composite prepared by reinforcing them with 5 wt % ZnO nanorods resulted in improved elastic modulus, stiffness, and hardness values by 32%, 14% and 35%, respectively, compared to neat polymer thin films. The viscoelastic dynamics of the composites revealed that there was an 11% increase in elastic wave speed in the composite, containing 5 wt % ZnO nanorods, indicating better response to high impacts. Delayed viscoelastic response decreased by 67% spatially and 51% temporally, with a corresponding decrease in the creep rate, for the 5 wt % ZnO nanorod- containing composite, evidencing its potential applicability in high strength lightweight structures. The improved mechanical properties with respect to the filler concentration evidence strong particle–polymer interfacial interactions, creating “chain-bound” clusters, providing clear reinforcement and polymer chain mobility retardation. However, hypervelocity impact testing revealed that all the composites’ films were vulnerable to hypervelocity impact, but the spallation region of the composite films reinforced with 2.5 wt % and 5 wt % ZnO nanorods exhibited a cellular-like matrix with shock-induced voids compared to a rather hardened spallation region with cracks in the neat film.
Mass Spectrometry Insight for Assessing the Destiny of Plastics in Seawater
Authors: Kuznetsova Olga V. , Shtykov Sergey N. , Timerbaev Andrei R.
Published: March 2023

Plastic pollution has become an increasingly serious environmental issue that requires using reliable analytical tools to unravel the transformations of primary plastics exposed to the marine environment. Here, we evaluated the performance of the isotope ratio mass spectrometry (IRMS) technique for identifying the origin of polymer material contaminating seawater and monitoring the compositional alterations due to its chemical degradation. Of twenty-six plastic specimens available as consumer products or collected from the Mediterranean Sea, five plastics were shown to originate from biobased polymeric materials. Natural abundance carbon and hydrogen isotope measurements revealed that biopolymers incline to substantial chemical transformation upon a prolonged exposure to seawater and sunlight irradiation. To assess the seawater-mediated aging that leads to the release of micro/nano fragments from plastic products, we propose to use microfiltration. Using this non-destructive separation technique as a front end to IRMS, the fragmentation of plastics (at the level of up to 0.5% of the total mass for plant-derived polymers) was recorded after a 3-month exposure and the rate and extent of disintegration were found to be substantially different for the different classes of polymers. Another potential impact of plastics on the environment is that toxic metals are adsorbed on their surface from the seashore water. We addressed this issue by using inductively coupled mass spectrometry after nitric acid leaching and found that several metals occur in the range of 0.1–90 µg per g on naturally aged plastics and accumulate at even higher levels (up to 10 mg g−1) on pristine plastics laboratory-aged in contaminated seawater. This study measured the degradation degree of different polymer types in seawater, filling in the gaps in our knowledge about plastic pollution and providing a useful methodology and important reference data for future research.
Effect of Ultrasonication Parameters on the Structural, Morphological, and Electrical Properties of Polypyrrole Nanoparticles and Optimization by Response Surface Methodology
Authors: Hossain SK Safdar , Rahman Anis Farhana Abdul , Arsad Agus , Basu Avijit , Pang Ai Ling , Harun Zakiah , Alwi Muhammad Mudassir Ahmad , Ali Syed Sadiq
Published: March 2023

Polypyrrole (PPy) nanoparticles are reliable conducting polymers with many industrial applications. Nevertheless, owing to disadvantages in structure and morphology, producing PPy with high electrical conductivity is challenging. In this study, a chemical oxidative polymerization-assisted ultra-sonication method was used to synthesize PPy with high conductivity. The influence of critical sonication parameters such as time and power on the structure, morphology, and electrical properties was examined using response surface methodology. Various analyses such as SEM, FTIR, DSC, and TGA were performed on the PPy. An R2 value of 0.8699 from the regression analysis suggested a fine correlation between the observed and predicted values of PPy conductivity. Using response surface plots and contour line diagrams, the optimum sonication time and sonication power were found to be 17 min and 24 W, respectively, generating a maximum conductivity of 2.334 S/cm. Meanwhile, the model predicted 2.249 S/cm conductivity, indicating successful alignment with the experimental data and incurring marginal error. SEM results demonstrated that the morphology of the particles was almost spherical, whereas the FTIR spectra indicated the presence of certain functional groups in the PPy. The obtained PPy with high conductivity can be a promising conducting material with various applications, such as in supercapacitors, sensors, and other smart electronic devices.
A Comprehensive Study of Polyurethane Potting Compounds Doped with Magnesium Oxide Nanoparticles
Authors: Hornak Jaroslav , Černohous Jakub , Prosr Pavel , Rous Pavel , Trnka Pavel , Baran Anton , Hardoň Štefan
Published: March 2023

Recently, polyurethanes (PURs) have become a very promising group of materials with considerable utilization and innovation potential. This work presents a comprehensive analysis of the changes in material properties important for PUR applications in the electrical industry due to the incorporation of magnesium oxide (MgO) nanoparticles at different weight ratios. From the results of the investigations carried out, it is evident that the incorporation of MgO improves the volume (by up to +0.5 order of magnitude) and surface (+1 order of magnitude) resistivities, reduces the dielectric losses at higher temperatures (−62%), improves the thermal stability of the material, and slows the decomposition reaction of polyurethane at specific temperatures (+30 °C). In contrast, the incorporation of MgO results in a slight decrease in the dielectric strength (−15%) and a significant decrease in the mechanical strength (−37%).
Understanding Marine Biodegradation of Bio-Based Oligoesters and Plasticizers
Authors: Zappaterra Federico , Renzi Monia , Piccardo Manuela , Spennato Mariachiara , Asaro Fioretta , Di Serio Martino , Vitiello Rosa , Turco Rosa , Todea Anamaria , Gardossi Lucia
Published: March 2023

The study reports the enzymatic synthesis of bio-based oligoesters and chemo-enzymatic processes for obtaining epoxidized bioplasticizers and biolubricants starting from cardoon seed oil. All of the molecules had MW below 1000 g mol−1 and were analyzed in terms of marine biodegradation. The data shed light on the effects of the chemical structure, chemical bond lability, thermal behavior, and water solubility on biodegradation. Moreover, the analysis of the biodegradation of the building blocks that constituted the different bio-based products allowed us to distinguish between different chemical and physicochemical factors. These hints are of major importance for the rational eco-design of new benign bio-based products. Overall, the high lability of ester bonds was confirmed, along with the negligible effect of the presence of epoxy rings on triglyceride structures. The biodegradation data clearly indicated that the monomers/building blocks undergo a much slower process of abiotic or biotic transformations, potentially leading to accumulation. Therefore, the simple analysis of the erosion, hydrolysis, or visual/chemical disappearance of the chemical products or plastic is not sufficient, but ecotoxicity studies on the effects of such small molecules are of major importance. The use of natural feedstocks, such as vegetable seed oils and their derivatives, allows the minimization of these risks, because microorganisms have evolved enzymes and metabolic pathways for processing such natural molecules.
Biopolymers Produced by Lactic Acid Bacteria: Characterization and Food Application
Authors: Nicolescu Cristina Mihaela , Bumbac Marius , Buruleanu Claudia Lavinia , Popescu Elena Corina , Stanescu Sorina Geanina , Georgescu Andreea Antonia , Toma Siramona Maria
Published: March 2023

Plants, animals, bacteria, and food waste are subjects of intensive research, as they are biological sources for the production of biopolymers. The topic links to global challenges related to the extended life cycle of products, and circular economy objectives. A severe and well-known threat to the environment, the non-biodegradability of plastics obliges different stakeholders to find legislative and technical solutions for producing valuable polymers which are biodegradable and also exhibit better characteristics for packaging products. Microorganisms are recognized nowadays as exciting sources for the production of biopolymers with applications in the food industry, package production, and several other fields. Ubiquitous organisms, lactic acid bacteria (LAB) are well studied for the production of exopolysaccharides (EPS), but much less as producers of polylactic acid (PLA) and polyhydroxyalkanoates (PHAs). Based on their good biodegradability feature, as well as the possibility to be obtained from cheap biomass, PLA and PHAs polymers currently receive increased attention from both research and industry. The present review aims to provide an overview of LAB strains’ characteristics that render them candidates for the biosynthesis of EPS, PLA, and PHAs, respectively. Further, the biopolymers’ features are described in correlation with their application in different food industry fields and for food packaging. Having in view that the production costs of the polymers constitute their major drawback, alternative solutions of biosynthesis in economic terms are discussed.
Imaginary Coating Algorithm Approaching Dense Accumulation of Granular Material in Simulations with Discrete Element Method
Authors: Wang Fei , Huang Yrjö Jun , Xuan Chen
Published: March 2023

The difficulty of obtaining a densely packed granular material as an initial condition is a very common problem in numerical simulations of granular materials. In this article, an Imaginary Coating Algorithm (ICA) is introduced. To avoid unreasonable particle deformation when using a longer time step and a lower Young’s modulus, the radii used in calculating the action forces in a binary collision are slightly larger than the real values. In other words, an imaginary coat is added to each particle or element. To validate this algorithm, simulations were carried out by using ÅDEM, and a A Discrete Element Method (DEM) software program was developed. Compared with traditional Simulated Annealing Algorithms (SAA), this technique can approach the densely packed state with less CPU/GPU time and is easy to operate.
Processing Strategies for Extraction and Concentration of Bitter Acids and Polyphenols from Brewing By-Products: A Comprehensive Review
Authors: Silva Klycia Fidélis Cerqueira e , Strieder Monique Martins , Pinto Mariana Barreto Carvalhal , Rostagno Maurício Ariel , Hubinger Miriam Dupas
Published: March 2023

Annually, 221 million tons of agro-food by-products are generated worldwide, causing diverse environmental issues due to incorrect discharge. Hot trub, spent hops, brewer’s spent grains, and brewer’s spent yeast are the by-products produced in the beer manufacturing chain. These by-products contain fibers, proteins, polyphenols, essential oils, and taste compounds, presenting high possibilities of use as alternative raw materials. In this review, we compiled the knowledge gaps of brewing by-product reuse, from phytochemical compound extractions to concentration approaches, mainly concerning bitter acids and polyphenols. Moreover, we assessed and discussed the emerging technologies and alternative solvents that have allowed for higher extraction yields. We illustrated the importance of purification and concentration steps of non-destructive methods for added value in products from reuse approaches. Finally, we showed the relevance of scale-up and economic feasibility studies in order to encourage the implementation of facilities that produce bitter acids and polyphenols from alternative sources such as hot trub and spent hops.
Association between Vitamin D Status and Health Status of Adults in Western Libya
Authors: Aljazzaf Badriyah , Alghazeer Rabia , Swehli Abubaker I. , Erhuma Mabruk , Elgmati Entisar , Muammer Masud S. , Torban Taher , AL-Farga Ammar , Alansari Wafa S. , Eskandrani Areej A. , Shamlan Ghalia , Al-Griw Mohamed A.
Published: March 2023

Vitamin D (VitD) is essential for health and preventing diseases. This study aimed to investigate the possible association between VitD status and health status in 306 Libyan male and female young adults (18–25 Y) and adults (26–65 Y). There were 89.54% of subjects that had VitD levels below normal (<30 ng/mL), of which 45.42% were VitD deficient (<10 ng/mL) and 44.12% were VitD insufficient (10–29.9 ng/mL). VitD deficiency was associated with higher fasting blood sugar (FBS), low-density lipoprotein (LDL), and triacylglycerol (TAG) levels. Young adults had lower VitD levels than adults, which was associated with some health conditions. VitD insufficiency was associated with higher body mass index (BMI) values in adults, especially females, with higher FBS levels in adult males and higher hemoglobin A1c (HbA1c) levels in adult females. VitD deficiency in young adults was associated with higher TAG levels (more likely in adults) and lower high-density lipoprotein (HDL) values. Furthermore, VitD deficient adult females appeared to have a higher risk of sleeping problems, psychological disorders, headache, and osteoporosis, whereas their male counterparts appeared to be at a higher risk of developing obesity and diabetes mellitus (DM). Findings showed a serious prevalence of VitD inadequacy in the Libyan population, which appears to negatively affect health status and be associated with some disease conditions.
Study on Performance Comparison of Two Hydrogen Liquefaction Processes Based on the Claude Cycle and the Brayton Refrigeration Cycle
Authors: Yang Jian , Li Yanzhong , Tan Hongbo
Published: March 2023

Hydrogen liquefaction is an essential section for efficient storage and transportation of hydrogen energy. Both the Claude cycle and Brayton refrigeration cycle are available for large-scale hydrogen liquefaction systems. Two large-scale hydrogen liquefiers with the liquefaction capacity of 120 t/d based on the Brayton refrigeration cycle and the Claude cycle, respectively, are analyzed and compared in this study. Sensitivity analysis is used to optimize the parameters of two liquefaction systems in HYSYS. According to the results, the exergy loss and specific energy consumption of the Claude liquefier are 18.98 MW and 5.62 kWh/kgLH, which are 6.6% and 4.4% less than those of the Brayton liquefier, respectively. Exergy analysis reveals the exergy loss of compression and expansion systems in the Claude liquefier is less than that of the Brayton liquefier, while the exergy loss of the throttle valve in the Claude liquefier is more notable. In addition, the molar flow rate of hydrogen used as refrigerant in the Claude liquefier is 10.6% less than that of refrigerant in the Brayton liquefier. Owing to the smaller size requirements of equipment and the lower specific energy consumption, the Claude cycle is more suitable for large-scale hydrogen liquefaction processes.
Numerical Simulation and Process Enhancement of the Hydrolysis of 2-Chlorobenzal Chloride
Authors: Li Fei , Dong Liang , Yan Shenghu , Zhang Yue , Liu Jianwu , Tao Wenping , Nian Lichun , Fu Shuangcheng
Published: March 2023

Hydrolysis of 2-Chlorobenzal chloride is the primary production method of 2-chlobrobenzaldehyde in industry, but the reactor technologies and reaction processes of this method are traditional and underdeveloped, in which the dichotomous leaf hydrolysis agitator is commonly used, resulting in low efficiency during the hydrolysis process. In this article, ANSYS software was utilized to enhance the hydrolytic reactors used in industrial production by simulating and analyzing the dispersion characteristics of droplets in the reactor. The particle size distribution of dispersed phase droplets and the Sauter mean diameter (D32) were used to characterize the dispersion effect, and the dispersion characteristics of the dichotomous leaf agitator and the three-bladed back-curved impeller, three-bladed propeller impeller, open turbine impeller, and crescent impeller were compared and studied. The results showed that there was a log-linear relationship between the D32 of the dispersed phase and the stirring speed in different systems; the number of tiny droplets in the three-bladed back-curved impeller system increased remarkably, and the droplets size distribution width decreased significantly, achieving mass transfer enhancement in the hydrolysis reaction system. The reliability of the simulation results was verified by the measurement experiment using the Sauter mean diameter (D32) of dispersed phase droplets. The results showed that the Sauter mean diameter (D32) variation trend is consistent with that of the simulation, and the error between them is less than 10%. A lab-scale hydrolytic reactor was designed and produced based on the scheme of an industrial hydrolytic reactor equipped with a three-bladed back-curved impeller, the effect of the hydrolytic reaction was verified, and the process conditions were strengthened under the same conditions. The results showed that, compared with the case in the reactor using a dichotomous leaf hydrolysis agitator at the same reaction temperature and catalyst conditions, the reaction time of hydrolysis completion reduced to 58.33% at the lab-scale, and to 63.89% at the industrial-scale at the stirring rate of 446 r/min, using a three-bladed back-curved impeller. These results provide a technical scheme and a basis for process strengthening for improving the production efficiency of 2-chlorobenzaldehyde production equipment in industry.
Chemically Activated Glass-Ionomer Cements as Bioactive Materials in Dentistry: A Review
Authors: Makanjuola John , Deb Sanjukta
Published: March 2023

The prospect of repair, regeneration, and remineralisation of the tooth tissue is currently transitioning from the exploratory stages to successful clinical applications with materials such as dentine substitutes that offer bioactive stimulation. Glass-ionomer or polyalkenoate cements are widely used in oral healthcare, especially due to their ability to adhere to the tooth structure and fluoride-releasing capacity. Since glass-ionomer cements exhibit an inherent ability to adhere to tooth tissue, they have been the subject of modifications to enhance bioactivity, biomineralisation, and their physical properties. The scope of this review is to assess systematically the modifications of glass-ionomer cements towards bioactive stimulation such as remineralisation, integration with tissues, and enhancement of antibacterial properties.
The Current Status and Challenges of Templestay Programs in Korean Buddhism
Authors: Moon Hyungong , Somers Brian D.
Published: March 2023

Templestay is a Korean program where participants have the chance to stay in a Buddhist temple and explore the historic buildings, statues, and natural surroundings of the temple grounds, while experiencing meditation and Buddhist rituals first-hand. Launched in 2002, approximately six million participants have attended Templestay programs over the last 20 years. However, in contrast to the great successes during the first ten years of the program’s existence, the last ten years have met with a significant decline in rates of participation. The aim of this article is to investigate the rise and fall in these figures to better understand the current wants and needs of participants and to consider the future of the Templestay program. Through an analysis of statistics garnered by the Cultural Corps of Korean Buddhism and a review of research studies on the growth and development of Templestay, this article considers why the program has recently been in decline and suggests how this may be remedied. Particular attention is given to how the needs of diverse participants can be met within a religious environment. In the conclusion, this article suggests that the number of participants may be increased with the implementation of programs more universally applied across all Templestay sites. Furthermore, critical concerns about over-commercialization are warranted insofar as marketing compromises the sense of authenticity sought by participants.
The Story of Sadāprarudita’s Search for Dharma and the Worship of the Prajñāpāramitā Sūtra from India to Sixth-Century China
Authors: Zhao Wen
Published: March 2023

The story of bodhisattva Sadāprarudita’s search for Dharma in the Prajñāpāramitā Sūtra has served to successfully shape the characters of the Dharma seeker, bodhisattva Sadāprarudita, and the Dharma preacher (dharmabhāṇakas), bodhisattva Dharmodgata. This narrative carried much information about the veneration of the Prajñāpāramitā Sūtra in Indic contexts, and it also enthused Chinese Buddhists of the sixth century CE to create the Prajñāpāramitā Sūtra written in gold calligraphy. Emperor Wu of the Liang organized pañcavārṣika assemblies centred on the lectures and veneration of the gold-calligraphy Sūtra, and the Tiantai master Huisi made a vow to create such a scroll around the same time. In the relevant accounts, Chinese preachers are always associated with the Dharma preacher Dharmodgata in the narrative, which in turn enhanced their authority in the contexts in which they operated. The narrative thus helped to promote the transmission of the text across the cultural boundaries in which the Dharma preacher, as the embodied agent of the Prajñāpāramitā text, played a significant role.
How Do Muslims and Jews in Christian Countries See Each Other Today? A Survey Review
Authors: Jikeli Gunther
Published: March 2023

Muslim–Jewish relations have a long and complex history. However, notions that all Jews and Muslims are eternal enemies are proven wrong both historically and by today’s survey data. A comprehensive review of the available survey data from the last two decades provides a glimpse into the views of Muslims and Jews of each other in countries where both communities are a minority. It is based on 52 surveys from Austria, Belgium, Denmark, France, Germany, Hungary, Italy, Latvia, the Netherlands, Poland, Russia, Spain, Sweden, the U.K., and the U.S. 39 surveys include samples of Muslim respondents (38,000 in total) and 18 surveys include samples of Jewish respondents (52,000 in total). Five of these surveys include both Muslim and Jewish subsamples. Many Muslims and Jews acknowledge that the other community suffers from discrimination, albeit to varying degrees. Jews often see Islam and Muslim extremists as a threat to Jews, but most Jews, more than society in general, seem to distinguish between Muslim extremists and Muslims in general. Antisemitic attitudes are significantly higher among Muslims than among the general population in all surveys, even though the majority of Muslims in most European countries and in the United States do not exhibit antisemitic attitudes. The differences in anti-Jewish attitudes between Muslims and non-Muslims do not disappear when controlling for sociodemographic factors.
Theological Utilitarianism, Supervenience, and Intrinsic Value
Authors: Flannagan Matthew Alexander
Published: March 2023

Erik Wielenberg has argued that robust realism can account for the “common-sense moral belief” that “some things distinct from God are intrinsically good”. By contrast, theological stateism cannot account for this belief. Hence, robust realism has a theoretical advantage over all forms of theological stateism. This article criticizes Wielenberg’s argument. Wielenberg distinguishes between R and D-supervenience. The coherence of Wielenberg’s robust realism depends upon this distinction. I argue that this distinction undermines his critique of theological stateism. I will make three points. First, once you utilize the distinction between R and D-supervenience, his argument for the incompatibility of theological stateism and intrinsic value fails. Second, theological stateism is compatible with intrinsic value. The historical example of theological utilitarianism, expounded by thinkers George Berkeley and William Paley, shows someone can accept that moral properties simultaneously R supervene upon God’s will and D supervene upon the natural properties of actions. Third, robust realism and theological stateism are in the same boat regarding intrinsic value once we distinguish between R and D-supervenience.
Islam and the Politics of Secularism in Pakistan
Authors: Ahmed Zahid Shahab
Published: March 2023

In terms of their political and ideological success, Pakistani Islamists have had several ups and downs since Pakistan became the Islamic Republic in 1956. Islamists strive to safeguard the Islamic state’s status quo while simultaneously expanding the reach of Sharia. Despite insignificant electoral victories, Islamists have largely been able to dictate national identity policies to civilian and military governments. A major hurdle to the promotion of pluralism in Pakistan is noticeable through persistent opposition to secularism by major political actors. Despite different political ideologies, major political parties refrain from promoting secularism in Pakistan; however, such views are more rigid in the case of Islamists. The purpose of this article, therefore, is to examine and compare the discourses of Islamists and other political parties in relation to Pakistan’s identity, reforms and anti-Westernism, religious minorities, and secularism. Based on the analysis, this paper argues that the views of Islamists and non-religious political parties are very similar regarding Islam and Pakistan’s identity, secularism, and minority rights in Pakistan.
Digital Mapping of Soil Organic Carbon Using UAV Images and Soil Properties in a Thermo-Erosion Gully on the Tibetan Plateau
Authors: Ding Mengkai , Li Xiaoyan , Jin Zongyi
Published: March 2023

Thermo-erosion gullies (TGs) are typical thermokarst features in upland permafrost; the soil organic carbon (SOC) of TGs has an important influence on soil quality in cold regions. The objectives of this study were to estimate the spatial distribution of SOC content in a typical TG on the northeastern Tibetan Plateau in China by using soil properties from seven different TGs and covariates from unmanned aerial vehicle (UAV) images, and to characterize the SOC content changes in four representative landscape regions (NO-Slumping, Slumping1, Slumping2, and Slumped) within this typical TG. The support vector machine (SVM) was the optimal machine learning algorithm for SOC content prediction, which explained 53.06% (R2) of the SOC content variation. Silt content was the most influential factor which demonstrated a positive relationship with SOC content in different TGs. In addition, the SOC content in the TGs was related to the landscapes. Severe Slumping (Slumping2: 150.79 g·kg−1) had a lower SOC content than NO-Slumped (163.29 g·kg−1) and the initial slumping stage (Slumping1: 169.08 g·kg−1). The results suggested that SVM was an effective algorithm to obtain a profound understanding of the SOC content over space, while future research needs to pay more attention to the SOC content distribution in the different TGs.
Carbon Stock Prediction in Managed Forest Ecosystems Using Bayesian and Frequentist Geostatistical Techniques and New Generation Remote Sensing Metrics
Authors: Chinembiri Tsikai Solomon , Mutanga Onisimo , Dube Timothy
Published: March 2023

The study compares the performance of a hierarchical Bayesian geostatistical methodology with a frequentist geostatistical approach, specifically, Kriging with External Drift (KED), for predicting C stock using prediction aides from the Landsat-8 and Sentinel-2 multispectral remote sensing platforms. The frequentist geostatistical approach’s reliance on the long-run frequency of repeated experiments for constructing confidence intervals is not always practical or feasible, as practitioners typically have access to a single dataset due to cost constraints on surveys and sampling. We evaluated two approaches for C stock prediction using two new generation multispectral remote sensing datasets because of the inherent uncertainty characterizing spatial prediction problems in the unsampled locations, as well as differences in how the Bayesian and frequentist geostatistical paradigms handle uncertainty. Information on C stock spectral prediction in the form of NDVI, SAVI, and EVI derived from multispectral remote sensing platforms, Landsat-8 and Sentinel-2, was used to build Bayesian and frequentist-based C stock predictive models in the sampled plantation forest ecosystem. Sentinel-2-based C stock predictive models outperform their Landsat-8 counterparts using both the Bayesian and frequentist inference approaches. However, the Bayesian-based Sentinel-2 C stock predictive model (RMSE = 0.17 MgCha−1) is more accurate than its frequentist-based Sentinel-2 (RMSE = 1.19 MgCha−1) C stock equivalent. The Sentinel-2 frequentist-based C stock predictive model gave the C stock prediction range of 1 ≤ MgCha−1 ≤ 290, whilst the Sentinel-2 Bayesian-based C stock predictive model resulted in the prediction range of 1 ≤ MgCha−1 ≤ 285. However, both the Bayesian and frequentist C stock predictive models built with the Landsat-8 sensor overpredicted the sampled C stock because the range of predicted values fell outside the range of the observed C stock values. As a result, we recommend and conclude that the Bayesian-based C stock prediction method, when it is combined with high-quality remote sensing data such as that of Sentinel-2, is an effective inferential statistical methodology for reporting C stock in managed plantation forest ecosystems.
Prior Semantic Information Guided Change Detection Method for Bi-temporal High-Resolution Remote Sensing Images
Authors: Pang Shiyan , Li Xinyu , Chen Jia , Zuo Zhiqi , Hu Xiangyun
Published: March 2023

High-resolution remote sensing image change detection technology compares and analyzes bi-temporal or multitemporal high-resolution remote sensing images to determine the change areas. It plays an important role in land cover/use monitoring, natural disaster monitoring, illegal building investigation, military target strike effect analysis, and land and resource investigation. The change detection of high-resolution remote sensing images has developed rapidly from data accumulation to algorithm models because of the rapid development of technologies such as deep learning and earth observation in recent years. However, the current deep learning-based change detection methods are strongly dependent on large sample data, and the training model has insufficient cross-domain generalization ability. As a result, a prior semantic information-guided change detection framework (PSI-CD), which alleviates the change detection model’s dependence on datasets by making full use of prior semantic information, is proposed in this paper. The proposed method mainly includes two parts: one is a prior semantic information generation network that uses the semantic segmentation dataset to extract robust and reliable prior semantic information; the other is the prior semantic information guided change detection network that makes full use of prior semantic information to reduce the sample size of the change detection. To verify the effectiveness of the proposed method, we produced pixel-level semantic labels for the bi-temporal images of the public change detection dataset (LEVIR-CD). Then, we performed extensive experiments on the WHU and LEVIR-CD datasets, including comparisons with existing methods, experiments with different amounts of data, and ablation study, to show the effectiveness of the proposed method. Compared with other existing methods, our method has the highest IoU for all training samples and different amounts of training samples on WHU and LEVIR-CD, reaching a maximum of 83.25% and 83.80%, respectively.
A Performance Analysis of Soil Dielectric Models over Organic Soils in Alaska for Passive Microwave Remote Sensing of Soil Moisture
Authors: Zhang Runze , Chan Steven , Bindlish Rajat , Lakshmi Venkataraman
Published: March 2023

Passive microwave remote sensing of soil moisture (SM) requires a physically based dielectric model that quantitatively converts the volumetric SM into the soil bulk dielectric constant. Mironov 2009 is the dielectric model used in the operational SM retrieval algorithms of the NASA Soil Moisture Active Passive (SMAP) and the ESA Soil Moisture and Ocean Salinity (SMOS) missions. However, Mironov 2009 suffers a challenge in deriving SM over organic soils, as it does not account for the impact of soil organic matter (SOM) on the soil bulk dielectric constant. To this end, we presented a comparative performance analysis of nine advanced soil dielectric models over organic soil in Alaska, four of which incorporate SOM. In the framework of the SMAP single-channel algorithm at vertical polarization (SCA-V), SM retrievals from different dielectric models were derived using an iterative optimization scheme. The skills of the different dielectric models over organic soils were reflected by the performance of their respective SM retrievals, which was measured by four conventional statistical metrics, calculated by comparing satellite-based SM time series with in-situ benchmarks. Overall, SM retrievals of organic-soil-based dielectric models tended to overestimate, while those from mineral-soil-based models displayed dry biases. All the models showed comparable values of unbiased root-mean-square error (ubRMSE) and Pearson Correlation (R), but Mironov 2019 exhibited a slight but consistent edge over the others. An integrated consideration of the model inputs, the physical basis, and the validated accuracy indicated that the separate use of Mironov 2009 and Mironov 2019 in the SMAP SCA-V for mineral soils (SOM <15%) and organic soils (SOM ≥15%) would be the preferred option.
Coupled Coordination Analysis between Urbanization and Eco-Environment in Ecologically Fragile Areas: A Case Study of Northwestern Sichuan, Southwest China
Authors: Li Yike , Li Xinzhe , Lu Tao
Published: March 2023

In China, rapid urbanization in recent decades has led to increasingly serious ecological and environmental problems, threatening sustainable development. Thus, a clear understanding of the relationship between urbanization and eco-environment is the basis for achieving regional sustainable development. However, despite the current global explosion of research interests on this topic, few studies have focused on ecologically fragile areas. To fill this gap, taking Aba Autonomous Prefecture in the eastern Qinghai-Tibet Plateau as a case study, we explored the relationship between urbanization and eco-environment from 2001 to 2018 using a coupled coordination degree model. The results show that the urbanization level and eco-environmental quality in Aba Prefecture achieved stable and continuous improvements from 0.202 to 0.428 and 0.372 to 0.422, respectively. Moreover, the coupling degree between them ranged from 0.524 to 0.652, indicating that the study area had transformed from uncoordinated development in the initial stage to transformation development in the final stage. Additionally, over the 18 years, the coordinated state of urbanization and eco-environment improved, with the coordinated level increasing from reluctant to moderate coordination after 2011. Lastly, we confirmed that urbanization in Aba Prefecture had an overall positive effect on the local eco-environment, although it gradually decreased as urbanization progressed. These findings have important implications for political decision-makers to achieve high-quality development in ecologically fragile areas.
First Retrieval of Total Ozone Columns from EMI-2 Using the DOAS Method
Authors: Qian Yuanyuan , Luo Yuhan , Zhou Haijin , Yang Taiping , Xi Liang , Si Fuqi
Published: March 2023

The Environmental Trace Gases Monitoring Instrument 2 (EMI-2), a second-generation Chinese hyperspectral satellite-based spectrometer, was launched on 7 September 2021. The total ozone column (TOC) product, which is one of the most important elements of the EMI-2 mission, is required for monitoring the Antarctic ozone hole and regional tropospheric ozone pollution. The first EMI-2 TOC results using the differential optical absorption spectroscopy (DOAS) method are presented in this study. Significant improvements, such as the fitting interval, reference spectrum, and iterative air mass factor (AMF) calculation scheme, were implemented in the EMI-2 TOC retrieval in comparison with the EMI DOAS TOC algorithm, thus generating more accurate reads. The monthly average EMI-2 DOAS TOCs in November 2021 were compared with the TROPOspheric Monitoring Instrument (TROPOMI) TOCs, and the results showed a good correlation (R = 0.99). The EMI-2 TOCs showed similar global spatial distributions to those of TROPOMI, with an overall mean relative bias and mean standard deviation of 0.16% and 2.38%, respectively. However, large differences (up to 7%) appeared in some polar areas near the coastline, which were mainly caused by different surface albedo algorithms. Furthermore, ground-based measurements from 20 stations across different latitudes derived from the World Ozone and Ultraviolet Radiation Data Center dataset were used to assess the accuracy of the EMI-2 DOAS TOCs, and they had a mean relative bias and mean standard deviation of 0.70% and 3.65%, respectively. These results indicate that the EMI-2 DOAS TOC algorithm can yield reliable global TOCs and monitor daily Antarctic TOCs for assessing the healing of ozone holes.
Multi-Scale and Multi-Stream Fusion Network for Pansharpening
Authors: Jian Lihua , Wu Shaowu , Chen Lihui , Vivone Gemine , Rayhana Rakiba , Zhang Di
Published: March 2023

Pansharpening refers to the use of a panchromatic image to improve the spatial resolution of a multi-spectral image while preserving spectral signatures. However, existing pansharpening methods are still unsatisfactory at balancing the trade-off between spatial enhancement and spectral fidelity. In this paper, a multi-scale and multi-stream fusion network (named MMFN) that leverages the multi-scale information of the source images is proposed. The proposed architecture is simple, yet effective, and can fully extract various spatial/spectral features at different levels. A multi-stage reconstruction loss was adopted to recover the pansharpened images in each multi-stream fusion block, which facilitates and stabilizes the training process. The qualitative and quantitative assessment on three real remote sensing datasets (i.e., QuickBird, Pléiades, and WorldView-2) demonstrates that the proposed approach outperforms state-of-the-art methods.
BPG-Based Lossy Compression of Three-Channel Noisy Images with Prediction of Optimal Operation Existence and Its Parameters
Authors: Kovalenko Bogdan , Lukin Vladimir , Vozel Benoit
Published: March 2023

Nowadays, there is a clear trend toward increasing the number of remote-sensing images acquired and their average size. This leads to the need to compress the images for storage, dissemination, and transfer over communication lines where lossy compression techniques are more popular. The images to be compressed or some of their components are often noisy. They must therefore be compressed taking into account the properties of the noise. Due to the noise filtering effect obtained during lossy compression of noisy images, an optimal operating point (OOP) may exist. The OOP is a parameter that controls the compression for which the quality of the compressed image is closer (closest) to the corresponding noise-free image than the quality of the noisy (original, uncompressed) image according to some quantitative criterion (metric). In practice, it is important to know whether the OOP exists for a given image, because if the OOP exists, it is appropriate to perform the compression in the OOP or at least in its neighborhood. Since the real image is absent in practice, it is impossible to determine a priori whether the OOP exists or not. Here, we focus on three-channel-remote-sensing images and show that it is possible to easily predict the existence of the OOP. Furthermore, it is possible to predict the metric values or their improvements with appropriate accuracy for practical use. The BPG (better portable graphics) encoder is considered a special case of an efficient compression technique. As an initial design step, the case of additive white Gaussian noise with equal variance in the three components is considered. While previous research was mainly focused on predicting the improvement (reduction) of the PSNR and PSNR-HVS-M metrics, here we focus on the modern visual quality metrics, namely PSNR-HA and MDSI. We also discuss what to do if, according to the prediction, an OOP is absent. Examples of lossy compression of noisy three-channel remote sensing images are given. It is also shown that the use of three-dimensional compression provides a compression ratio increase by several times compared with component-wise compression in the OOP.
High Resolution Fourier Transform Spectrometer for Ground-Based Verification of Greenhouse Gases Satellites
Authors: Shi Hailiang , Xiong Wei , Ye Hanhan , Wu Shichao , Zhu Feng , Li Zhiwei , Luo Haiyan , Li Chao , Wang Xianhua
Published: March 2023

Satellite remote sensing is currently the best monitoring means to obtain global carbon source and sink data. The United States, Japan, China and other countries are vigorously developing spaceborne detection technology. However, the important factors that restrict the application of greenhouse gas satellite remote sensing technology include the limited accuracy of data products. How to improve the retrieval level of greenhouse gas payloads is a problem that needs to be solved urgently. One effective way to improve data quality is to carry out satellite ground synchronous authenticity verification and system error correction. This paper mainly aims at the shortcomings of the existing TCCON and the portable verification equipment EM27/SUN, and develops a High-Resolution Fourier Transform Spectrometer (HRFTS) based on dynamic collimation technology. Through the gas absorption method and the band scanning method of the hyperspectral monochromatic light source, the instrument’s absorption spectrum measurement capability and the Instrument Line Shape (ILS) are demonstrated. The instrument’s spectral resolution is consistent with the on-orbit greenhouse gas satellite load, reaching 0.26 cm−1. For the interference data obtained by the spectrometer, spectral restoration processing, data quality control and inversion algorithm optimization were carried out to solve the problems of baseline correction, spectral fine registration, and environmental parameter profile reconstruction, and cross comparison experiments with EM27/SUN were carried out simultaneously. Finally, for the gases monitoring instrument (GMI) of the GF5-02 satellite launched on 7 September 2021, the first satellite ground synchronization verification experiment with high space-time matching was carried out. The results showed that the CO2 column concentration deviation of the satellite ground synchronization inversion was about 1.5 ppm, and the CH4 column concentration deviation was about 11.3 ppb, which verified the on-orbit detection accuracy of the GMI, and laid a foundation for the subsequent satellite inversion algorithm optimization and systematic error correction.
Increasing the Resolution and Spectral Range of Measured Direct Irradiance Spectra for PV Applications
Authors: López Gabriel , Gueymard Christian A. , Polo Jesús , Alonso-Montesinos Joaquín , Marzo Aitor , Martín-Chivelet Nuria , Ferrada Pablo , Escalona-Llaguno Martha Isabel , Batlles Francisco Javier
Published: March 2023

The spectral distribution of the solar irradiance incident on photovoltaic (PV) modules is a key variable controlling their power production. It is required to properly simulate the production and performance of PV plants based on technologies with different spectral characteristics. Spectroradiometers can only sense the solar spectrum within a wavelength range that is usually too short compared to the actual spectral response of some PV technologies. In this work, a new methodology based on the Simple Model of the Atmospheric Radiative Transfer of Sunshine (SMARTS) spectral code is proposed to extend the spectral range of measured direct irradiance spectra and to increase the spectral resolution of such experimental measurements. Satisfactory results were obtained for both clear and hazy sky conditions at a radiometric station in southern Spain. This approach constitutes the starting point of a general methodology to obtain the instantaneous spectral irradiance incident on the plane of array of PV modules and its temporal variations, while evaluating the magnitude and variability of the abundance of atmospheric constituents with the most impact on surface irradiance, most particularly aerosols and water vapor.