bluuebunny/crossref_metadata_2025 huggingface dataset:
Copper Ions Absorbed on Acrylic-Acid-Grafted Polystyrene Enable Direct Bonding with Tunable Bonding Strength and Debonding on Demand
Authors: Günther Roman , Caseri Walter , Brändli Christof
Published: November 2022

Recycling adhesively bonded polymers is inconvenient due to its expensive separation and removal of adhesive residues. To tackle this problem, adhesive technologies are needed allowing debonding on demand and which do not contaminate the surface of the substrate. Direct bonding enabled by oxygen plasma treatment has already achieved substantial adhesion between flat substrates. However, debonding takes place by water, thus limiting the applications of this technology to water-free environments. The work presented in the following shows that this drawback can be overcome by grafting acrylic acid and adding copper(II) ions on the surface of polystyrene. In this process, the number of functional groups on the surface was significantly increased without increasing the surface roughness. The bonding strength between the substrates could be increased, and the process temperature could be lowered. Nevertheless, the samples could be debonded by exposure to EDTA solution under ultrasound. Hence, by combining acrylic acid grafting, variations in the bonding temperatures and the use of copper(II) ions, the bonding strength (5 N to >85 N) and the debonding time under the action of water can be tuned over large ranges (seconds to complete resistance).
3D Bioprinting for Pancreas Engineering/Manufacturing
Authors: Xu Yukun , Song Dabin , Wang Xiaohong
Published: November 2022

Diabetes is the most common chronic disease in the world, and it brings a heavy burden to people’s health. Against this background, diabetic research, including islet functionalization has become a hot topic in medical institutions all over the world. Especially with the rapid development of microencapsulation and three-dimensional (3D) bioprinting technologies, organ engineering and manufacturing have become the main trends for disease modeling and drug screening. Especially the advanced 3D models of pancreatic islets have shown better physiological functions than monolayer cultures, suggesting their potential in elucidating the behaviors of cells under different growth environments. This review mainly summarizes the latest progress of islet capsules and 3D printed pancreatic organs and introduces the activities of islet cells in the constructs with different encapsulation technologies and polymeric materials, as well as the vascularization and blood glucose control capabilities of these constructs after implantation. The challenges and perspectives of the pancreatic organ engineering/manufacturing technologies have also been demonstrated.
Controlled and Synchronised Vascular Regeneration upon the Implantation of Iloprost- and Cationic Amphiphilic Drugs-Conjugated Tissue-Engineered Vascular Grafts into the Ovine Carotid Artery: A Proteomics-Empowered Study
Authors: Antonova Larisa , Kutikhin Anton , Sevostianova Viktoriia , Lobov Arseniy , Repkin Egor , Krivkina Evgenia , Velikanova Elena , Mironov Andrey , Mukhamadiyarov Rinat , Senokosova Evgenia , Khanova Mariam , Shishkova Daria , Markova Victoria , Barbarash Leonid
Published: November 2022

Implementation of small-diameter tissue-engineered vascular grafts (TEVGs) into clinical practice is still delayed due to the frequent complications, including thrombosis, aneurysms, neointimal hyperplasia, calcification, atherosclerosis, and infection. Here, we conjugated a vasodilator/platelet inhibitor, iloprost, and an antimicrobial cationic amphiphilic drug, 1,5-bis-(4-tetradecyl-1,4-diazoniabicyclo [2.2.2]octan-1-yl) pentane tetrabromide, to the luminal surface of electrospun poly(ε-caprolactone) (PCL) TEVGs for preventing thrombosis and infection, additionally enveloped such TEVGs into the PCL sheath to preclude aneurysms, and implanted PCLIlo/CAD TEVGs into the ovine carotid artery (n = 12) for 6 months. The primary patency was 50% (6/12 animals). TEVGs were completely replaced with the vascular tissue, free from aneurysms, calcification, atherosclerosis and infection, completely endothelialised, and had clearly distinguishable medial and adventitial layers. Comparative proteomic profiling of TEVGs and contralateral carotid arteries found that TEVGs lacked contractile vascular smooth muscle cell markers, basement membrane components, and proteins mediating antioxidant defense, concurrently showing the protein signatures of upregulated protein synthesis, folding and assembly, enhanced energy metabolism, and macrophage-driven inflammation. Collectively, these results suggested a synchronised replacement of PCL with a newly formed vascular tissue but insufficient compliance of PCLIlo/CAD TEVGs, demanding their testing in the muscular artery position or stimulation of vascular smooth muscle cell specification after the implantation.
Synthesis of a Novel Bifunctional Epoxy Double-Decker Silsesquioxane: Improvement of the Thermal Stability and Dielectric Properties of Polybenzoxazine
Authors: Sun Xiaoyi , Wang Jing , Fu Qixuan , Zhang Qian , Xu Riwei
Published: November 2022

In this study a new type of bifunctional epoxy compound (DDSQ-EP) based on double-decker silsesquioxane (DDSQ) was synthesized by process of alkaline hydrolysis condensation of phenyltrimethoxysilane and corner capping reaction with dichloromethylvinylsilane, followed by epoxidation reaction of vinyl groups. The resultant structures were confirmed using Fourier transform infrared spectrometry, nuclear magnetic resonance spectrometry and time-of-flight mass spectrometry, respectively. The DDSQ-EP was incorporated into polybenzoxazine to obtain the PBZ/DDSQ-EP nanocomposites. The uniform dispersion of DDSQ-EP in the nanocomposites was verified by X-ray diffraction and scanning electron microscope. The reactions occurred during the curing of the composites and were investigated using infrared spectroscopy of segmented cures. Dynamic mechanical analysis and thermal gravimetric analysis indicated that the storage modulus, glass transition temperature and thermal stability of PBZ/DDSQ-EP were increased in comparison with pure benzoxazine resins. Assessment of dielectric properties demonstrated that the dielectric permittivity and dielectric loss of polybenzoxazine decreased slightly because of the addition of DDSQ-EP.
Colloidal Crystal Films with Narrow Reflection Bands by Hot-Pressing of Polymer-Grafted Silica Particles
Authors: Matsuura Sawa , Obara Mami , Iwata Naoto , Furumi Seiichi
Published: November 2022

Previous reports have shown that colloidal crystal (CC) films with visible Bragg reflection characteristics can be fabricated by the surface modification of monodisperse silica particles (SiPs) with poly(methyl methacrylate) (PMMA) chains, followed by hot-pressing at 150 °C. However, the reflection bands of the CC films were very broad due to their relative disordering of SiPs. In this report, we attempted to fabricate the CC films using SiPs surface-modified with poly(n-octyl acrylate) (POA) chains by hot-pressing. When the cast films of POA-grafted SiPs were prepared by hot-pressing at 100 °C, the reflection bands were narrow rather than those of CC films of PMMA-grafted SiPs. This can be ascribed to easy disentanglement of POA chains during the hot-pressing process, thereby enabling the formation of well-ordered CC structures. Moreover, the reflection colors of CC films could be easily tuned by controlling the molecular weight of POA chains grafted on the SiP surface.
Monomers Release from Direct and Indirect Resin-Based Restorations after Immersion in Common Beverages
Authors: Mourouzis Petros , Vladitsi Magdalini , Nikolaou Charalampia , Kalogiouri Natasa P. , Samanidou Victoria , Tolidis Kosmas
Published: November 2022

Impurities or degradation of the components of resin-based materials have been throughout investigated by the dental scientific community. The aim of this study is to examine if there is a release of monomers from resin-based materials when they are immersed in common beverage materials which are consumed by the population in large quantities. Three representative dental materials were used for this study, one resin composite indicated for direct restorations and two Computer Aided Design and Computer Aided Manufacturing (CAD/CAM) materials with different methods of fabrication. Forty specimens were fabricated from each material using a low-speed precision sectioning blade 12 × 14 × 2 mm in size and immersed in wine, coffee or cola for 48 h and 12 days, equivalent to 1 month and 1 year of consumption. The materials released more monomers when the materials were immersed in the wine solution (p < 0.05). CAD/CAM materials release less monomers compared to the resin composite material indicated for direct restorations (p < 0.05). The CAD/CAM materials leach a limited quantity of monomers when they are immersed in common beverages due to the manufacturing process which includes high-temperature/high-pressure polymerization.
Fabrication of Superhydrophobic/Superoleophilic Bamboo Cellulose Foam for Oil/Water Separation
Authors: Liu Chun-Hua , Shang Jiao-Ping , Su Xing , Zhao Shuang , Peng Yun , Li Yi-Bao
Published: November 2022

Water is an indispensable strategic resource for biological and social development. The problem of oily wastewater pollution originating from oil spillages, industrial discharge and domestic oil pollution has become an extremely serious international challenge. At present, numerous superwetting materials have been applied to effectively separate oil and water. However, most of these materials are difficult to scale and their large–scale application is limited by cost and environmental protection. Herein, a simple, environmentally friendly strategy including sol–gel, freeze–drying and surface hydrophobic modification is presented to fabricate a bamboo cellulose foam with special wetting characteristics. The bamboo cellulose foam is superhydrophobic, with a water contact angle of 160°, and it has the superoleophilic property of instantaneous oil absorption. Owing to the synergistic effect of the three–dimensional network structure of the superhydrophobic bamboo cellulose foam and its hydrophobic composition, it has an excellent oil–absorption performance of 11.5 g/g~37.5 g/g for various types of oil, as well as good recyclability, with an oil (1,2–dichloroethane) absorption capacity of up to 31.5 g/g after 10 cycles. In addition, the prepared cellulose–based foam exhibits an outstanding performance in terms of acid and alkali corrosion resistance. Importantly, owing to bamboo cellulose being a biodegradable, low–cost, natural polymer material that can be easily modified, superhydrophobic/superoleophilic bamboo cellulose foam has great application potential in the field of oily wastewater treatment.
A Review on Chitosan and Cellulose Hydrogels for Wound Dressings
Authors: Elangwe Collins N. , Morozkina Svetlana N. , Olekhnovich Roman O. , Krasichkov Alexander , Polyakova Victoriya O. , Uspenskaya Mayya V.
Published: November 2022

Wound management remains a challenging issue around the world, although a lot of wound dressing materials have been produced for the treatment of chronic and acute wounds. Wound healing is a highly dynamic and complex regulatory process that involves four principal integrated phases, including hemostasis, inflammation, proliferation, and remodeling. Chronic non-healing wounds are wounds that heal significantly more slowly, fail to progress to all the phases of the normal wound healing process, and are usually stalled at the inflammatory phase. These wounds cause a lot of challenges to patients, such as severe emotional and physical stress and generate a considerable financial burden on patients and the general public healthcare system. It has been reported that about 1–2% of the global population suffers from chronic non-healing wounds during their lifetime in developed nations. Traditional wound dressings are dry, and therefore cannot provide moist environment for wound healing and do not possess antibacterial properties. Wound dressings that are currently used consist of bandages, films, foams, patches and hydrogels. Currently, hydrogels are gaining much attention as a result of their water-holding capacity, providing a moist wound-healing milieu. Chitosan is a biopolymer that has gained a lot of attention recently in the pharmaceutical industry due to its unique chemical and antibacterial nature. However, with its poor mechanical properties, chitosan is incorporated with other biopolymers, such as the cellulose of desirable biocompatibility, at the same time having the improved mechanical and physical properties of the hydrogels. This review focuses on the study of biopolymers, such as cellulose and chitosan hydrogels, for wound treatment.
Composition, Properties, and Utilization of Fumaric Acid Sludge By-Produced from Industrial Phthalic Anhydride Wastewater Treatment
Authors: Wei Zhongjin , Zhou Fengshan , Chen Sinan , Zhao Hongxing
Published: November 2022

To understand fumaric acid sludge (FAS) systematically and comprehensively and find out how to utilize it, we conducted a series of characterization analyses on FAS. Fourier transform infrared (FT-IR) Spectra shows that the main component of FAS is fumaric acids and also contains a small amount of silicate. The nuclear magnetic resonance hydrogen (1H-NMR) spectrum also shows that fumaric acid accounted for a large proportion of FAS. The X-ray diffraction (XRD) shows that the main phase in FAS is fumaric acid, and there is also a small amount of Kaliophilite. After gas chromatography and mass spectrometry (GC-MS) and pyrolysis gas chromatography and mass spectrometry (Py-GC-MS) analysis, it indicates that the possible volatiles and pyrolysis products in FAS are fumaric acid, maleic acid, maleic anhydride, phthalic acid, etc. In the test of Liquid chromatography and mass spectrometry (LC-MS), we determined the contents of phthalic acid, fumaric acid, and maleic acid in FAS. The detailed mass content of each component in FAS is as follows: phthalic acid is about 0.10–0.15%; maleic anhydride is about 0.40–0.80%; maleic acid is about 18.40–19.0%; fumaric acid is about 55.00–56.90%; succinic anhydride is about 0.06–0.08%; acrylic acid is about 0.06–0.08%; malic acid is about 0.90–1.00%; acetic acid is about 0.10–0.20%; silicate is about 0.25–0.30%; phthalic anhydride is about 0.20–0.30%; water is about 24.30–24.80%. The filtrate loss reducer (PAAF) used in oilwell drilling fluids synthesized by FAS not only has excellent temperature and complex saline resistance, the API filtration loss (FL) was only 13.2 mL/30 min in the complex saline based mud, but is also cost-effective.
Stability of Properties of Layer-by-Layer Coated Membranes under Passage of Electric Current
Authors: Solonchenko Ksenia , Rybalkina Olesya , Chuprynina Daria , Kirichenko Evgeniy , Kirichenko Ksenia , Nikonenko Victor
Published: November 2022

Electrodialysis with layer-by-layer coated membranes is a promising method for the separation of monovalent and polyvalent ions. Since the separation selectivity is significantly reduced in the presence of defects in the multilayer system, the stability of the modifiers becomes an important issue. This article reports the i-V curves of layer-by-layer coated membranes based on the heterogeneous MK-40 membrane before and after 50 h long electrodialysis of a solution containing sodium and calcium ions at an underlimiting current density, and the values of concentrations of cations in the desalination chamber during electrodialysis. It is shown that the transport of bivalent ions through the modified membranes is reduced throughout the electrodialysis by about 50%, but the operation results in decreased resistance of the membrane modified with polyethylenimine, which may suggest damage to the modifying layer. Even after electrodialysis, the modified membrane demonstrated experimental limiting current densities higher than that of the substrate, and in case of the membrane modified with polyallylamine, the limiting current density 10% higher than that of the substrate membrane.
Chitosan-Graft-Poly(acrylic acid) Superabsorbent’s Water Holding in Sandy Soils and Its Application in Agriculture
Authors: Jayanudin  , Lestari Retno S. D. , Barleany Dhena Ria , Pitaloka Alia Badra , Yulvianti Meri , Prasetyo Dimas , Anggoro Dendy Vito , Ruhiatna Adam
Published: November 2022

Sandy soil has a low ability to absorb and store low water, low nutrient content, and a high water evaporation rate, so it is not suitable to be used as agricultural land. Superabsorbents can be used to overcome these weaknesses. The purpose of this study was to measure the abilities of the superabsorbents, including water holding, swelling, and water retention of sandy soil enriched with superabsorbent, and to analyze the chitosan-graft-poly(acrylic acid) superabsorbent characteristics. The superabsorbent was prepared by mixing a chitosan solution with ammonium persulfate as an initiator and acrylic acid, which had been neutralized with KOH. Then, the mixture was cross-linked with N,N′-methylenebisacrylamide (MBA). The resulting superabsorbent gel was dried in an oven and then crushed for analysis. The results showed that an increase in chitosan concentration increased the gel fraction, swelling, reusability, and water holding. Meanwhile, an increase in chitosan concentration decreased water retention in sandy soils. The swelling kinetics can be predicted using the pseudo-second-order model with high accuracy (R2 value of 0.99).
Valorization of Kraft Lignin from Black Liquor in the Production of Composite Materials with Poly(caprolactone) and Natural Stone Groundwood Fibers
Authors: Tarrés Quim , Aguado Roberto , Domínguez-Robles Juan , Larrañeta Eneko , Delgado-Aguilar Marc
Published: November 2022

The development of new materials is currently focused on replacing fossil-based plastics with sustainable materials. Obtaining new bioplastics that are biodegradable and of the greenest possible origin could be a great alternative for the future. However, there are some limitations—such as price, physical properties, and mechanical properties—of these bioplastics. In this sense, the present work aims to explore the potential of lignin present in black liquor from paper pulp production as the main component of a new plastic matrix. For this purpose, we have studied the simple recovery of this lignin using acid precipitation, its thermoplastification with glycerin as a plasticizing agent, the production of blends with poly(caprolactone) (PCL), and finally the development of biocomposite materials reinforcing the blend of thermoplastic lignin and PCL with stone groundwood fibers (SGW). The results obtained show that thermoplastic lignin alone cannot be used as a bioplastic. However, its combination with PCL provided a tensile strength of, e.g., 5.24 MPa in the case of a 50 wt.% blend. In addition, when studying the properties of the composite materials, it was found that the tensile strength of a blend with 20 wt.% PCL increased from 1.7 to 11.2 MPa with 40 wt.% SGW. Finally, it was proven that through these biocomposites it is possible to obtain a correct fiber–blend interface.
Shi’a Women in Italy: Between Tradition and Traditionalism
Authors: Mirshahvalad Minoo
Published: November 2022

Through the case study of 20 Shi’a organisations in Italy, this article aims to explore the meanings of traditionalism and how it grows among certain Shi’a women who are members of these organisations. The article compares the two differing and antithetical ways in which Shi’a women relate to their traditions, one being spontaneous and emotional, the other rational and discursive. The primary objective is to show that the rationalisation of tradition, or traditionalism, develops only among women willing and capable of relating to their European host context. Instead of an organic tendency, Shi’a traditionalism emerges in this case as a reaction to Italian society, tailored to deal with the social concerns that surface in the Apennine peninsula. The social concerns eventually propel women to revamp their religious heritage.
Jewish–Christian Interaction in Ethiopia as Reflected in Sacred Geography: Expressing Affinity with Jerusalem and the Holy Land and Comemorating the Betä Ǝsraʾel–Solomonic Wars
Authors: Kribus Bar
Published: November 2022

Affinity with the Holy Land, and especially with Jerusalem, is a common theme in the sacred geography of Abrahamic religions, expressed in prayer houses and holy sites. This theme was especially prominent in Solomonic Ethiopia, both among Ethiopian Orthodox Christians and among the Betä Ǝsraʾel (Ethiopian Jews). This article will examine expressions of affinity with Jerusalem and the Holy Land in Betä Ǝsraʾel holy sites and religious architecture, and shed light on the interreligious discourse related to such expressions, as well as other forms of interreligious discourse expressed by these two communities in sacred geography. This will demonstrate that in Solomonic Ethiopia, affinity with the Holy Land was a core element in expressing an Israelite identity. Both the Betä Ǝsraʾel and the Ethiopian Orthodox Christians saw themselves as the biological and spiritual heirs of the biblical Israelites, and this concept played a key role in shaping their sacred geography to allude to biblical sites and events. This will also demonstrate that, building upon a vocabulary with common features, the sacred geography and religious architecture of each community was a means to express its unique identity. As such, it provides insight regarding differences in religious concepts.
Can You Be Grateful to a Benefactor Whose Existence You Doubt?
Authors: Manela Tony
Published: November 2022

Among philosophers who study gratitude, there is much disagreement about what gratitude is and when it is called for. One thesis no one has questioned, however, is the thesis that in order to be grateful to a benefactor, a beneficiary must believe that that benefactor exists. In this essay, I lay out novel reasons to doubt this thesis, and I explore a striking implication of rejecting it: the implication that doubters of various kinds—not just religious people in periods of doubt, but also lifelong agnostics, and even some atheists—might be capable of gratitude to God. I begin by developing a hypothetical case that demonstrates people can be grateful to human benefactors whose existence they doubt. My case shows that gratitude to a doubted benefactor is consistent with hoping that benefactor turns out not to exist. I then show how my case implies that theists in periods of doubt, agnostics, and a particular kind of atheist could be grateful to God, despite a lack of belief in his existence, and despite a lack of faith in God.
The Creation of Jiansi: Study on the Buddhist Monastic Supervision System during the Sui and Tang Dynasties
Authors: Guo Jing
Published: November 2022

Besides the internal monastic supervision system of the “Three Principal Monks” already prevalent in the Sui and Tang dynasties, an additional lay-involved supervision system of jiansi was further added to the state religious policy to strengthen the control over the autonomy of the Buddhist community. This jiansi system can be seen once in the period of Gaochang Kingdom (449–640) in the Turpan region, and is traceable to the role of the Lay Rectifier of Monks created by Emperor Wu of Liang (r. 502–549) in the Southern dynasty. It is then officially created by Emperor Yang of Sui (r. 604–618) but failed quickly in the Tang dynasty. In the late Tang dynasty, it re-emerged in response to the state’s need to strengthen the control over Buddhist affairs and extended to new grassroots monastic officials such as Monastic Minister and Saṃgha Regulator in the Dunhuang area during the Tibetan occupation period and the Guiyi Army period. Thus, the development and evolution of the jiansi system in this period was both a reflection of the state-religion tension and a sinicization process of Buddhism.
Retrieving Soil Moisture in the Permafrost Environment by Sentinel-1/2 Temporal Data on the Qinghai–Tibet Plateau
Authors: Li Zhibin , Zhao Lin , Wang Lingxiao , Zou Defu , Liu Guangyue , Hu Guojie , Du Erji , Xiao Yao , Liu Shibo , Zhou Huayun , Xing Zanpin , Wang Chong , Zhao Jianting , Chen Yueli , Qiao Yongping , Shi Jianzong
Published: November 2022

Soil moisture (SM) products presently available in permafrost regions, especially on the Qinghai–Tibet Plateau (QTP), hardly meet the demands of evaluating and modeling climatic, hydrological, and ecological processes, due to their significant bias and low spatial resolution. This study developed an algorithm to generate high-spatial-resolution SM during the thawing season using Sentinel-1 (S1) and Sentinel-2 (S2) temporal data in the permafrost environment. This algorithm utilizes the seasonal backscatter differences to reduce the effect of surface roughness and uses the normalized difference vegetation index (NDVI) and the normalized difference moisture index (NDMI) to characterize vegetation contribution. Then, the SM map with a grid spacing of 50 m × 50 m in the hinterland of the QTP with an area of 505 km × 246 km was generated. The results were independently validated based on in situ data from active layer monitoring sites. It shows that this algorithm can retrieve SM well in the study area. The coefficient of determination (R2) and root-mean-square error (RMSE) are 0.82 and 0.06 m3/m3, respectively. This study analyzed the SM distribution of different vegetation types: the alpine swamp meadow had the largest SM of 0.26 m3/m3, followed by the alpine meadow (0.23), alpine steppe (0.2), and alpine desert (0.16), taking the Tuotuo River basin as an example. We also found a significantly negative correlation between the coefficient of variation (CV) and SM in the permafrost area, and the variability of SM is higher in drier environments and lower in wetter environments. The comparison with ERA5-Land, GLDAS, and ESA CCI showed that the proposed method can provide more spatial details and achieve better performance in permafrost areas on QTP. The results also indicated that the developed algorithm has the potential to be applied in the entire permafrost regions on the QTP.
Tempo-Spatial Distributions and Transport Characteristics of Two Dust Events over Northern China in March 2021
Authors: Sun Xiaoguang , Fan Xuehua , Zhang Tianle , Wang Yinan , Wang Yuntao , Lyu Daren , Zheng Mei
Published: November 2022

The Taklamakan Desert and the Gobi Desert in East Asia constitute the second-largest sources of dust in the world. In particular, dust originating from the Gobi Desert is more susceptible to long-range transport, with consequent impacts in downwind Asian countries and the Northwest Pacific region. Two intensive dust events (the 3·15 dust event and the 3·28 dust event) were experienced in North China in March 2021. The 3·15 dust process was rated as the most intensive dust process in China in the past 10 years. In this study, by using a combination of spaceborne remote sensing datasets from geostationary and polar-orbiting satellites, ground-based columnar observations of aerosol optical parameters, meteorological reanalysis data, and backward trajectory simulations of air masses, the transport pathways and the three-dimensional structure characteristics of dust aerosols during the transport of the two dust events in March 2021 were cross-validated. The results of the study indicated that the two dust events were induced by the Mongolian cyclone. Due to the different configurations of the ground meteorological system conditions, a backflow process occurred during the 3·15 dust event transmission process. After passing over North China and the Bohai Sea, the direction of transport of the dust plume was reversed. The wind deflected from northwest to northeast, and the dust reached the eastern coastal areas of China and was finally deposited on land. The 3·28 dust event exhibited aerosol stratification in the transport path, the higher pure dust layer reached up to 9 km height, and the lower layer underwent aerosol mixing and became a polluted dust aerosol. This study implies that the investigation of dust aerosol transport and the deposition processes, the impact on the ocean, and the impact of marine aerosols on land also needs to be taken into consideration; the integration of advanced satellites and ground-based remote sensing data, the meteorological reanalysis data and the backward trajectories simulation, which complemented and verified each other, can enhance the ability to delineate the transport pathways and the three-dimensional structural characteristics of dust events.
Predicting the Forest Canopy Height from LiDAR and Multi-Sensor Data Using Machine Learning over India
Authors: Ghosh Sujit M. , Behera Mukunda D. , Kumar Subham , Das Pulakesh , Prakash Ambadipudi J. , Bhaskaran Prasad K. , Roy Parth S. , Barik Saroj K. , Jeganathan Chockalingam , Srivastava Prashant K. , Behera Soumit K.
Published: November 2022

Forest canopy height estimates, at a regional scale, help understand the forest carbon storage, ecosystem processes, the development of forest management and the restoration policies to mitigate global climate change, etc. The recent availability of the NASA’s Global Ecosystem Dynamics Investigation (GEDI) LiDAR data has opened up new avenues to assess the plant canopy height at a footprint level. Here, we present a novel approach using the random forest (RF) for the wall-to-wall canopy height estimation over India’s forests (i.e., evergreen forest, deciduous forest, mixed forest, plantation, and shrubland) by employing the high-resolution top-of-the-atmosphere (TOA) reflectance and vegetation indices, the synthetic aperture radar (SAR) backscatters, the topography and tree canopy density, as the proxy variables. The variable importance plot indicated that the SAR backscatters, tree canopy density and the topography are the most influential height predictors. 33.15% of India’s forest cover demonstrated the canopy height <10 m, while 44.51% accounted for 10–20 m and 22.34% of forests demonstrated a higher canopy height (>20 m). This study advocates the importance and use of GEDI data for estimating the canopy height, preferably in data-deficit mountainous regions, where most of India’s natural forest vegetation exists.
How Many Pan-Arctic Lakes Are Observed by ICESat-2 in Space and Time?
Authors: Chen Tan , Song Chunqiao , Zhan Pengfei , Ma Jinsong
Published: November 2022

High-latitude lakes are sensitive indicators of climate change. Monitoring lake dynamics in high-latitude regions (e.g., pan-Arctic regions) is essential to improving our understanding of the impacts of climate change; however, the lack of in situ water level measurements limits comprehensive quantification of the lake hydrologic dynamics in high-latitude regions. Fortunately, the newly launched ICESat-2 laser altimeter can provide finer footprint measurements and denser ground tracks, thus enabling us to measure the water level changes for more lakes than with conventional radar altimeters. This study aims to comprehensively assess the number and frequency of pan-Arctic lakes (>1 km2, north of 60°N) observable by the ICESat-2 in space and time over the past three years. Further, we analyze the spatial and temporal characteristics of the ICESat-2-based water level observations of these pan-Arctic lakes based on our customized classification of seasonal coverage patterns (wet/dry season, monthly, and ten-day). We find that the ICESat-2 observed 80,688 pan-Arctic lakes (97% of the total). Among the observed lakes, the ICESat-2 retrieved the seasonal coverage patterns for 40,192 lakes (~50% of observed lakes), accounting for nearly 84% of the area and 95% of the volumetric capacity. Most lakes (99%) have seasonal water-level fluctuation amplitudes within a range of 0–1 m. The latitudinal zonality analysis demonstrates that the seasonal change in pan-Arctic lake levels gently fluctuates around 0.5 m between 60°N and 74°N and becomes intense (range of level change from 1 m to 2 m) beyond 74°N. Our results are expected to offer an overall reference for the spatio-temporal coverage of the ICESat-2’s observations of pan-Arctic lakes, which is crucial for comprehending the hydrologic response of high-latitude lakes to ongoing climate change.
Assessing Potential Spontaneous Combustion of Coal Gangue Dumps after Reclamation by Simulating Alfalfa Heat Stress Based on the Spectral Features of Chlorophyll Fluorescence Parameters
Authors: Wang Qiyuan , Zhao Yanling , Xiao Wu , Lin Zihan , Ren He
Published: November 2022

The spontaneous combustion of coal gangue dumps after reclamation causes severe harm to the ecological environment surrounding mining areas. Using remote sensing technology to determine vegetation heat stress levels is an important way to evaluate the probability of a spontaneous combustion disaster. The canopy spectra and chlorophyll fluorescence (ChlF) parameters of alfalfa were collected through pot experiments to simulate different heat stress levels. Time series analyses of three ChlF (chlorophyll fluorescence) parameters showed that the regularity of the quantum efficiency of photosystem II (PSII) in light-adapted conditions (Fv′/Fm′) was stronger during the monitoring period. The correlation coefficients between the three ChlF parameters and the canopy raw spectrum, first derivative spectrum, and vegetation indices were calculated, and the spectral features were found to be more correlated. Lasso regression was used to further screen spectral features, and the optimal spectral features were the raw spectral value at 741 nm (abbreviated as RS (741)) and NDVI (652, 671). To discriminate among heat stress levels accurately and automatically, we built a time convolution neural network. The classification results showed that when the sequence length is 3, the heat stress is divided into three categories, and the model obtains the highest accuracy. In combination with relevant research conclusions on the temperature distribution law of spontaneous combustion in coal gangue dumps, three heat stress levels can be used to assess the potential of spontaneous combustion in coal gangue dumps after reclamation. The research results provide an important theoretical basis and technical support for early warnings regarding spontaneous combustion disasters in reclaimed coal gangue dumps.
Gaussian Process Modeling of In-Season Physiological Parameters of Spring Wheat Based on Airborne Imagery from Two Hyperspectral Cameras and Apparent Soil Electrical Conductivity
Authors: Żelazny Wiktor R. , Kusnierek Krzysztof , Geipel Jakob
Published: November 2022

The remote sensing of the biophysical and biochemical parameters of crops facilitates the preparation of application maps for variable-rate nitrogen fertilization. According to comparative studies of machine learning algorithms, Gaussian process regression (GPR) can outperform more popular methods in the prediction of crop status from hyperspectral data. The present study evaluates GPR model accuracy in the context of spring wheat dry matter, nitrogen content, and nitrogen uptake estimation. Models with the squared exponential covariance function were trained on images from two hyperspectral cameras (a frenchFabry–Pérot interferometer camera and a push-broom scanner). The most accurate predictions were obtained for nitrogen uptake (R2=0.75–0.85, RPDP=2.0–2.6). Modifications of the basic workflow were then evaluated: the removal of soil pixels from the images prior to the training, data fusion with apparent soil electrical conductivity measurements, and replacing the Euclidean distance in the GPR covariance function with the spectral angle distance. Of these, the data fusion improved the performance while predicting nitrogen uptake and nitrogen content. The estimation accuracy of the latter parameter varied considerably across the two hyperspectral cameras. Satisfactory nitrogen content predictions (R2>0.8, RPDP>2.4) were obtained only in the data-fusion scenario, and only with a high spectral resolution push-broom device capable of capturing longer wavelengths, up to 1000 nm, while the full-frame camera spectral limit was 790 nm. The prediction performance and uncertainty metrics indicated the suitability of the models for precision agriculture applications. Moreover, the spatial patterns that emerged in the generated crop parameter maps accurately reflected the fertilization levels applied across the experimental area as well as the background variation of the abiotic growth conditions, further corroborating this conclusion.
In-Memory Distributed Mosaicking for Large-Scale Remote Sensing Applications with Geo-Gridded Data Staging on Alluxio
Authors: Ma Yan , Song Jie , Zhang Zhixin
Published: November 2022

The unprecedented availability of petascale analysis-ready earth observation data has given rise to a remarkable surge in demand for regional to global environmental studies, which exploit tons of data for temporal–spatial analysis at a much larger scale than ever. Imagery mosaicking, which is critical for forming “One Map” with a continuous view for large-scale climate research, has drawn significant concern. However, despite employing distributed data processing engines such as Spark, large-scale data mosaicking still significantly suffers from a staggering number of remote sensing images which could inevitably lead to discouraging performance. The main ill-posed problem of traditional parallel mosaicking algorithms is inherent in the huge computation demand and incredible heavy data I/O burden resulting from intensively shifting tremendous RS data back and forth between limited local memory and bulk external storage throughout the multiple processing stages. To address these issues, we propose an in-memory Spark-enabled distributed data mosaicking at a large scale with geo-gridded data staging accelerated by Alluxio. It organizes enormous “messy” remote sensing datasets into geo-encoded gird groups and indexes them with multi-dimensional space-filling curves geo-encoding assisted by GeoTrellis. All the buckets of geo-grided remote sensing data groups could be loaded directly from Alluxio with data prefetching and expressed as RDDs implemented concurrently as grid tasks of mosaicking on top of the Spark-enabled cluster. It is worth noticing that an in-memory data orchestration is offered to facilitate in-memory big data staging among multiple mosaicking processing stages to eliminate the tremendous data transferring at a great extent while maintaining a better data locality. As a result, benefiting from parallel processing with distributed data prefetching and in-memory data staging, this is a much more effective approach to facilitate large-scale data mosaicking in the context of big data. Experimental results have demonstrated our approach is much more efficient and scalable than the traditional ways of parallel implementing.
Estimation of Soil Freeze Depth in Typical Snowy Regions Using Reanalysis Dataset: A Case Study in Heilongjiang Province, China
Authors: Wang Xiqiang , Chen Rensheng , Han Chuntan , Yang Yong , Liu Junfeng , Liu Zhangwen , Guo Shuhai
Published: November 2022

Soil freeze depth variations greatly affect energy exchange, carbon exchange, ecosystem diversity, and the water cycle. Given the importance of these processes, obtaining freeze depth data over large scales is an important focus of research. This paper presents a simple empirical algorithm to estimate the maximum seasonally frozen depth (MSFD) of seasonally frozen ground (SFG) in snowy regions. First, the potential influences of driving factors on the MSFD variations were quantified in the baseline period (1981–2010) based on the 26 meteorological stations within and around the SFG region of Heilongjiang province. The three variables that contributed more than 10% to MSFD variations (i.e., air freezing index, annual mean snow depth, and snow cover days) were considered in the analysis. A simple multiple linear regression to estimate soil freeze depth was fitted (1981–2010) and verified (1975–1980 and 2011–2014) using ground station observations. Compared with the commonly used simplified Stefan solution, this multiple linear regression produced superior freeze depth estimations, with the mean absolute error and root mean square error of the station average reduced by over 20%. By utilizing this empirical algorithm and the ERA5-Land reanalysis dataset, the multi-year average MSFD (1981–2010) was 132 cm, ranging from 52 cm to 186 cm, and MSFD anomaly exhibited a significant decreasing trend, at a rate of −0.38 cm/decade or a net change of −28.14 cm from 1950–2021. This study provided a practical approach to model the soil freeze depth of SFG over a large scale in snowy regions and emphasized the importance of considering snow cover variables in analyzing and estimating soil freeze depth.
A Deep Learning Based Method to Delineate the Wet/Dry Shoreline and Compute Its Elevation Using High-Resolution UAS Imagery
Authors: Vicens-Miquel Marina , Medrano F. Antonio , Tissot Philippe E. , Kamangir Hamid , Starek Michael J. , Colburn Katie
Published: November 2022

Automatically detecting the wet/dry shoreline from remote sensing imagery has many benefits for beach management in coastal areas by enabling managers to take measures to protect wildlife during high water events. This paper proposes the use of a modified HED (Holistically-Nested Edge Detection) architecture to create a model for automatic feature identification of the wet/dry shoreline and to compute its elevation from the associated DSM (Digital Surface Model). The model is generalizable to several beaches in Texas and Florida. The data from the multiple beaches was collected using UAS (Uncrewed Aircraft Systems). UAS allow for the collection of high-resolution imagery and the creation of the DSMs that are essential for computing the elevations of the wet/dry shorelines. Another advantage of using UAS is the flexibility to choose locations and metocean conditions, allowing to collect a varied dataset necessary to calibrate a general model. To evaluate the performance and the generalization of the AI model, we trained the model on data from eight flights over four locations, tested it on the data from a ninth flight, and repeated it for all possible combinations. The AP and F1-Scores obtained show the success of the model’s prediction for the majority of cases, but the limitations of a pure computer vision assessment are discussed in the context of this coastal application. The method was also assessed more directly, where the average elevations of the labeled and AI predicted wet/dry shorelines were compared. The absolute differences between the two elevations were, on average, 2.1 cm, while the absolute difference of the elevations’ standard deviations for each wet/dry shoreline was 2.2 cm. The proposed method results in a generalizable model able to delineate the wet/dry shoreline in beach imagery for multiple flights at several locations in Texas and Florida and for a range of metocean conditions.
Evaluating Data Inter-Operability of Multiple UAV–LiDAR Systems for Measuring the 3D Structure of Savanna Woodland
Authors: Bartholomeus Harm , Calders Kim , Whiteside Tim , Terryn Louise , Krishna Moorthy Sruthi M. , Levick Shaun R. , Bartolo Renée , Verbeeck Hans
Published: November 2022

For vegetation monitoring, it is crucial to understand which changes are caused by the measurement setup and which changes are true representations of vegetation dynamics. UAV–LiDAR offers great possibilities to measure vegetation structural parameters; however, UAV–LiDAR sensors are undergoing rapid developments, and the characteristics are expected to keep changing over the years, which will introduce data inter-operability issues. Therefore, it is important to determine whether datasets acquired by different UAV–LiDAR sensors can be interchanged and if changes through time can accurately be derived from UAV–LiDAR time series. With this study, we present insights into the magnitude of differences in derived forest metrics in savanna woodland when three different UAV–LiDAR systems are being used for data acquisition. Our findings show that all three systems can be used to derive plot characteristics such as canopy height, canopy cover, and gap fractions. However, there are clear differences between the metrics derived with different sensors, which are most apparent in the lower parts of the canopy. On an individual tree level, all UAV–LiDAR systems are able to accurately capture the tree height in a savanna woodland system, but significant differences occur when crown parameters are measured with different systems. Less precise systems result in underestimations of crown areas and crown volumes. When comparing UAV–LiDAR data of forest areas through time, it is important to be aware of these differences and ensure that data inter-operability issues do not influence the change analysis. In this paper, we want to stress that it is of utmost importance to realise this and take it into consideration when combining datasets obtained with different sensors.
Review of Ground Penetrating Radar Applications for Water Dynamics Studies in Unsaturated Zone
Authors: Zhang Minghe , Feng Xuan , Bano Maksim , Xing Huiting , Wang Taihan , Liang Wenjing , Zhou Haoqiu , Dong Zejun , An Yafei , Zhang Yinghao
Published: November 2022

For water dynamics investigation in unsaturated (vadose) zones, ground penetrating radar is a popular hydro-geophysical method because it is non-invasive for soil, has high resolution and the results have a direct link with water content. Soil water content and soil hydraulic properties are two key factors for describing the water dynamics in vadose zones. There has been tremendous progress in soil water content and soil hydraulic properties estimation with ground penetrating radar. The purpose of this paper is to provide an overview of the application of ground penetrating radar for soil water dynamics studies. This paper first summarizes various methods for the determination of soil water content. including traditional methods in the surveys of surface ground penetrating radar, borehole ground penetrating radar, and off-ground ground penetrating radar, as well as relatively new methods, such as full waveform inversion, the average envelope amplitude method, and the frequency shift method. This paper further provides a review for estimating soil hydraulic properties with GPR according to the types of ground penetrating radar data. We hope that this review can provide a reference for the application of ground penetrating radar in soil water dynamics studies in the future.
Aerial Image Dehazing Using Reinforcement Learning
Authors: Yu Jing , Liang Deying , Hang Bo , Gao Hongtao
Published: November 2022

Aerial observation is usually affected by the Earth’s atmosphere, especially when haze exists. Deep reinforcement learning was used in this study for dehazing. We first developed a clear–hazy aerial image dataset addressing various types of ground; we then compared the dehazing results of some state-of-the-art methods, including the classic dark channel prior, color attenuation prior, non-local image dehazing, multi-scale convolutional neural networks, DehazeNet, and all-in-one dehazing network. We extended the most suitable method, DehazeNet, to a multi-scale form and added it into a multi-agent deep reinforcement learning network called DRL_Dehaze. DRL_Dehaze was tested on several ground types and in situations with multiple haze scales. The results show that each pixel agent can automatically select the most suitable method in multi-scale haze situations and can produce a good dehazing result. Different ground scenes may best be processed using different steps.