bluuebunny/crossref_metadata_2025 huggingface dataset:
Physiological Responses of Cigar Tobacco Crop to Nitrogen Deficiency and Genome-Wide Characterization of the NtNPF Family Genes
Authors: Guo Hao , He Xuyou , Zhang Hao , Tan Ronglei , Yang Jinpeng , Xu Fangsen , Wang Sheliang , Yang Chunlei , Ding Guangda
Published: November 2022

Tobacco prefers nitrate as a nitrogen (N) source. However, little is known about the molecular components responsible for nitrate uptake and the physiological responses of cigar tobacco to N deficiency. In this study, a total of 117 nitrate transporter 1 (NRT1) and peptide transporter (PTR) family (NPF) genes were comprehensively identified and systematically characterized in the whole tobacco genome. The NtNPF members showed significant genetic diversity within and across subfamilies but showed conservation between subfamilies. The NtNPF genes are dispersed unevenly across the chromosomes. The phylogenetic analysis revealed that eight subfamilies of NtNPF genes are tightly grouped with their orthologues in Arabidopsis. The promoter regions of the NtNPF genes had extensive cis-regulatory elements. Twelve core NtNPF genes, which were strongly induced by N limitation, were identified based on the RNA-seq data. Furthermore, N deprivation severely impaired plant growth of two cigar tobaccos, and CX26 may be more sensitive to N deficiency than CX14. Moreover, 12 hub genes respond differently to N deficiency between the two cultivars, indicating the vital roles in regulating N uptake and transport in cigar tobacco. The findings here contribute towards a better knowledge of the NtNPF genes and lay the foundation for further functional analysis of cigar tobacco.
Exploring Contact Toxicity of Essential Oils against Sitophilus zeamais through a Meta-Analysis Approach
Authors: Achimón Fernanda , Peschiutta Maria L. , Brito Vanessa D. , Beato Magalí , Pizzolitto Romina P. , Zygadlo Julio A. , Zunino María P.
Published: November 2022

Sitophilus zeamais is a primary pest of maize. Our aim was to perform a qualitative review and meta-analyses with 56 scientific articles published from 1 January 2000 to 1 October 2022 dealing with direct (topical application) and indirect (impregnation of essential oils, EOs, onto filter paper or maize grains) contact toxicity of EOs against S. zeamais. Three independent meta-analyses of single means of LD50 (direct contact) and LC50 (indirect contact) were conducted using a random effect model. Essential oils more frequently evaluated were those belonging to Asteraceae, Apiaceae, Lamiaceae, Myrtaceae, Piperaceae, and Rutaceae. The LC50 global mean values were 33.19 µg/insect (CI95 29.81–36.95) for topical application; 0.40 µL/cm2 (CI95 0.25–0.65) for filter paper indirect contact; and 0.50 µL/g maize (CI95 0.27–0.90) for maize grains indirect contact. The species Carum carvi, Salvia umbratica, Ilicium difengpi, Periploca sepium, Cephalotaxus sinensis, Murraya exotica, Rhododendron anthopogonoides, Ruta graveolens, Eucalyptus viminalis, Ocotea odorifera, Eucalyptus globulus, Eucalyptus dunnii, Anethum graveolens, Ilicium verum, Cryptocarya alba, Azadirachta indica, Chenopodium ambrosioides, Cupressus semperivens, Schinus molle, Piper hispidinervum, Mentha longifolia, and Croton pulegiodorus showed LC50 or LD50 values lower than the global means, indicating good insecticidal properties. Our results showed that EOs have great potential to be used as bioinsecticides against S. zeamais.
Phytosynthesis of Zinc Oxide Nanoparticles Using Ceratonia siliqua L. and Evidence of Antimicrobial Activity
Authors: Karmous Inès , Taheur Fadia Ben , Zuverza-Mena Nubia , Jebahi Samira , Vaidya Shital , Tlahig Samir , Mhadhbi Mohsen , Gorai Mustapha , Raouafi Amel , Debara Mohamed , Bouhamda Talel , Dimkpa Christian O.
Published: November 2022

Carob (Ceratonia siliqua L.) is a tree crop cultivated extensively in the eastern Mediterranean regions but that has become naturalized in other regions as well. The present study focused on the green synthesis of zinc oxide nanoparticles (ZnONPs) from Carob and their evaluation for antimicrobial activity in bacteria and fungi. The synthesized ZnONPs showed strong antibacterial activity against Staphylococcus aureus ATCC 25 923 (92%). The NPs inhibited the growth of pathogenic yeast strains, including Candida albicans ATCC90028, Candida krusei ATCC6258, and Candida neoformans ATCC14116, by 90%, 91%, and 82%, respectively, compared to the control. Fungal inhibition zones with the ZnONPs were 88.67% and 90%, respectively, larger for Aspergillus flavus 15UA005 and Aspergillus fumigatus ATCC204305, compared to control fungal growth. This study provides novel information relevant for plant-based development of new and potentially antimicrobial ZnONPs based on extracts. In particular, the development and application of phytogenic nanoparticles enhances the biocompatibility of nano-scale materials, thereby allowing to tune effects to prevent adverse outcomes in non-target biological systems.
Thermal and Mechanical Properties of Concrete Incorporating Silica Fume and Waste Rubber Powder
Authors: Lakhiar Muhammad Tahir , Kong Sih Ying , Bai Yu , Susilawati Susilawati , Zahidi Izni , Paul Suvash Chandra , Raghunandan Mavinakere Eshwaraiah
Published: November 2022

Using waste rubber tires for concrete production will reduce the demand for natural aggregate and help to reduce environmental pollution. The main challenge of using waste rubber tires in concrete is the deterioration of mechanical properties, due to poor bonding between rubber and cement matrix. This research aims to evaluate the mechanical and thermal properties of rubberised concrete produced by using different proportions of rubber powder and silica fume. Ordinary Portland cement was partially replaced with silica fume by amounts of 5%, 10%, 15% and 20%, while sand was replaced by 10%, 20% and 30% with waste rubber powder. Tests were carried out in order to determine workability, density, compressive strength, splitting tensile strength, elastic modulus, thermal properties, water absorption and shrinkage of rubberised concrete. The compressive strength and splitting tensile strength of concrete produced using waste rubber powder were reduced by 10–52% and 9–57%, respectively. However, the reduction in modulus of elasticity was 2–36%, less severe than compressive and splitting tensile strengths. An optimum silica fume content of 15% was observed based on the results of mechanical properties. The average shrinkage of concrete containing 15% silica fume increased from −0.051% to −0.085% at 28 days, as the content of waste rubber powder increased from 10% to 30%. While the thermal conductivity of rubberised concrete was reduced by 9–35% compared to the control sample. Linear equations were found to correlate the density, splitting tensile strength, modulus of elasticity and thermal conductivity of concrete with silica fume and waste rubber powder.
Polyurethane Recycling: Conversion of Carbamates—Catalysis, Side-Reactions and Mole Balance
Authors: Zamani Shahab , Lange Jean-Paul , Kersten Sascha R. A. , Ruiz M. Pilar
Published: November 2022

Diisocyanates, a key monomer in polyurethane, are generally lost during recycling. Polyurethane alcoholysis to carbamate and subsequent cracking to isocyanate represents a promising, phosgene-free recycling route. This work reports the thermal and catalytic cracking of a model carbamate (Methyl N-phenyl carbamate, MPC) to isocyanate (Phenyl isocyanate). Multiple catalysts (ZnO, Bi2O3, Al2O3, and Montmorillonite K-10) were evaluated in a closed system (batch autoclaves) to decompose MPC at temperatures of 160–200 °C, with a thorough analysis of the products and high (≥90%) mole balance. The thermal reaction was very limited at these temperatures, whereas the catalytic reaction led mainly to aniline and urea and seemed to be dominated by water adsorbed on the catalyst surface.
Phosphorylated Metal–Organic Framework for Reducing Fire Hazards of Poly(Methyl Methacrylate)
Authors: Wang Lei , Hu Ximiao , Mao Zhelin , Wang Jianlei , Wang Xin
Published: November 2022

The low fire safety performance (flame retardant and antistatic properties) of poly(methyl methacrylate) (PMMA) has severely limited practical applications. Here, a phosphorylated Zn-based metal–organic framework (ZIF-8-P) is employed as an effective flame retardant and antistatic agent to reduce the fire risk of PMMA. Encouragingly, the as-prepared PMMA/ZIF-8-P composite demonstrated not merely better mechanical properties (e.g., a rise of ca. 136.9% and 175.0% in the reduced modulus and hardness; a higher storage modulus), but also efficient fire safety properties (e.g., lower surface resistance; a decrease of ca. 73.1% in the peak heat release rate; a lower amount of total pyrolysis products), surpassing those of pure PMMA and a PMMA/ZIF-8 composite without phytic acid modification. Mechanism analysis is conducted to reveal the critical role of catalytic charring, char reinforcing, and the dilution of nonflammable gases from ZIF-8 additives during the combustion and pyrolysis process. Our study paves a promising way to achieve high performance PMMA composites.
A Comprehensive Study on Starch Nanoparticle Potential as a Reinforcing Material in Bioplastic
Authors: Marta Herlina , Wijaya Claudia , Sukri Nandi , Cahyana Yana , Mohammad Masita
Published: November 2022

Starch can be found in the stems, roots, fruits, and seeds of plants such as sweet potato, cassava, corn, potato, and many more. In addition to its original form, starch can be modified by reducing its size. Starch nanoparticles have a small size and large active surface area, making them suitable for use as fillers or as a reinforcing material in bioplastics. The aim of reinforcing material is to improve the characteristics of bioplastics. This literature study aims to provide in-depth information on the potential use of starch nanoparticles as a reinforcing material in bioplastic packaging. This study also reviews starch size reduction methods including acid hydrolysis, nanoprecipitation, milling, and others; characteristics of the nano-starch particle; and methods to produce bioplastic and its characteristics. The use of starch nanoparticles as a reinforcing material can increase tensile strength, reduce water vapor and oxygen permeability, and increase the biodegradability of bioplastics. However, the use of starch nanoparticles as a reinforcing material for bioplastic packaging still encounters obstacles in its commercialization efforts, due to high production costs and ineffectiveness.
Thermal Stability, Flammability and Mechanical Performances of Unsaturated Polyester–Melamine Resin Blends and of Glass Fibre-Reinforced Composites Based on Them
Authors: Krishnan Latha , Kandola Baljinder K. , Deli Dario , Ebdon John R.
Published: November 2022

A novel blend of unsaturated polyester (UP) resin with an inherently flame-retardant and char-forming melamine formaldehyde (MF) resin has been prepared with the aim of reducing the flammability of the former. MF resin, sourced as a spray-dried resin, was dissolved in diethyleneglycol solvent; the dissolved resin and the UP-MF blend were autocured by heating under conditions normally used for curing UP, i.e., room temperature for 24 h and post-curing at 80 °C for 12–24 h. The cured UP-MF blends, although heterogeneous in nature, were rigid materials having fire performances superior to those of the cured UP alone. The blends also burned, but with a much reduced smoke output compared with that from UP. Although the heterogeneity of the blends helped in improving the fire performances of the blends in terms of the MF domains forming a semi-protective char, acting as thermal barriers for the adjoining UP domains, and hence reducing their thermal degradation, the mechanical properties of composites based on them were impaired. Nevertheless, whilst UP/MF blends may not be suitable for use as matrices in glass-reinforced composites in load-bearing applications, they may lend themselves to applications as fire-retardant gel coats, especially in view of their low-smoke, char-forming attributes.
Experimental Investigation of Bi-Directional Flax with Ramie Fibre-Reinforced Phenol-Formaldehyde Hybrid Composites
Authors: Rajesh Durvasulu , Lenin Nagarajan , Cep Robert , Anand Palanivel , Elangovan Muniyandy
Published: November 2022

Modern research focuses on natural, green, and sustainable materials that can be used to replace conventional materials. Because of their beneficial qualities, natural fibre composites are being thoroughly researched. This research focuses on the development of a flax fibre reinforced with phenol-formaldehyde resin hybridization with ramie fibre through a vacuum infusion process. Eight different sequences were fabricated using a core–sheath structure and were mechanically characterized as per ASTM standards. The fabrication technique influences the adhesion of the matrix with reinforcement. The results also reveal that composite having ramie as a sheath layer and flax as a core delivers good mechanical characteristics compared to vice versa. The laminate H exhibited highest mechanical properties among all the eight laminates produced for this study. It exhibited a tensile strength of 54 MPa, tensile modulus of 0.98 Gpa, elongation of 7.1%, flexural strength of 143 Mpa, and compressive strength of 63.65 Mpa. The stress strain curves revealed that all the laminates exhibited ductile behaviour before failing during the tensile test and flexural test, respectively. The stacking sequence of the laminate H influenced the mechanical properties exhibited by it and its counterparts. A morphological study was carried out to analyse the failure surfaces. Morphological analysis exhibited few defects in the laminate after the tests. The composites developed delivers better mechanical properties than commercial composites available on the market, which can be used in lightweight structural applications.
Amphiphilic Copolymer-Lipid Chimeric Nanosystems as DNA Vectors
Authors: Chrysostomou Varvara , Foryś Aleksander , Trzebicka Barbara , Demetzos Costas , Pispas Stergios
Published: November 2022

Lipid-polymer chimeric (hybrid) nanosystems are promising platforms for the design of effective gene delivery vectors. In this regard, we developed DNA nanocarriers comprised of a novel poly[(stearyl methacrylate-co-oligo(ethylene glycol) methyl ether methacrylate] [P(SMA-co-OEGMA)] amphiphilic random copolymer, the cationic 1,2-dioleoyl-3-(trimethylammonium) propane (DOTAP), and the zwitterionic L-α-phosphatidylcholine, hydrogenated soybean (soy) (HSPC) lipids. Chimeric HSPC:DOTAP:P[(SMA-co-OEGMA)] nanosystems, and pure lipid nanosystems as reference, were prepared in several molar ratios of the components. The colloidal dispersions obtained presented well-defined physicochemical characteristics and were further utilized for the formation of lipoplexes with a model DNA of linear topology containing 113 base pairs. Nanosized complexes were formed through the electrostatic interaction of the cationic lipid and phosphate groups of DNA, as observed by dynamic, static, and electrophoretic light scattering techniques. Ultraviolet–visible (UV–Vis) and fluorescence spectroscopy disclosed the strong binding affinity of the chimeric and also the pure lipid nanosystems to DNA. Colloidally stable chimeric/lipid complexes were formed, whose physicochemical characteristics depend on the N/P ratio and on the molar ratio of the building components. Cryogenic transmission electron microscopy (Cryo-TEM) revealed the formation of nanosystems with vesicular morphology. The results suggest the successful fabrication of these novel chimeric nanosystems with well-defined physicochemical characteristics, which can form stable lipoplexes.
Irinotecan-Loaded Polymeric Micelles as a Promising Alternative to Enhance Antitumor Efficacy in Colorectal Cancer Therapy
Authors: Campos Fernanda Lapa , de Alcântara Lemos Janaina , Oda Caroline Mari Ramos , de Oliveira Silva Juliana , Fernandes Renata Salgado , Miranda Sued Eustaquio Mendes , Cavalcante Carolina Henriques , Cassali Geovanni Dantas , Townsend Danyelle M. , Leite Elaine Amaral , de Barros Andre Luis Branco
Published: November 2022

Colorectal cancer has been considered a worldwide public health problem since current treatments are often ineffective. Irinotecan is a frontline chemotherapeutic agent that has dose-limiting side effects that compromise its therapeutic potential. Therefore, it is necessary to develop a novel, targeted drug delivery system with high therapeutic efficacy and an improved safety profile. Here, micellar formulations composed of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethyleneglycol)-2000] (DSPE-mPEG2k) containing irinotecan were proposed as a strategy for colorectal cancer therapy. Firstly, the irinotecan-loaded micelles were prepared using the solvent evaporation method. Then, micelles were characterized in terms of size, polydispersity, zeta potential, entrapment efficiency, and release kinetics. Cytotoxicity and in vivo antitumor activity were evaluated. The micelles showed size around 13 nm, zeta potential near neutral (−0.5 mV), and encapsulation efficiency around 68.5% (irinotecan 3 mg/mL) with a sustained drug release within the first 8 h. The micelles were evaluated in a CT26 tumor animal model showing inhibition of tumor growth (89%) higher than free drug (68.7%). Body weight variation, hemolytic activity, hematological, and biochemical data showed that, at the dose of 7.5 mg/kg, the irinotecan-loaded micelles have low toxicity. In summary, our findings provide evidence that DSPE-mPEG2k micelles could be considered potential carriers for future irinotecan delivery and their possible therapeutic application against colorectal cancer.
Numerical Simulation of Hydraulic Fracturing and Penetration Law in Continental Shale Reservoirs
Authors: Zhao Yanxin , Wang Lei , Ma Kuo , Zhang Feng
Published: November 2022

The vertical heterogeneity of continental shale reservoirs is strong, the difference between lithology and stress between layers is large, the weak interface between layers develops, and the hydraulic fracture penetration and expansion are difficult, resulting in poor fracturing transformation effect. In view of this, based on the finite element and cohesive element method, this paper established a fluid-solid coupling model for the hydraulic fracture propagation through the continental shale and studied the control mechanism and influence law of various geological and engineering parameters on the hydraulic fracture propagation through the continental shale reservoir using single factor and orthogonal test analysis methods. Interfacial cementation strength between high layers, high vertical stress difference, low interlaminar stress difference, low tensile strength difference, low elastic modulus difference, high pressure fracturing fluid viscosity, and high injection displacement are conducive to the penetration and expansion of hydraulic fractures. The primary and secondary order of influence degree of each factor is: interlaminar interface cementation strength > interlaminar stress difference/tensile strength difference > fracturing fluid viscosity/injection displacement > vertical stress difference > elastic modulus. In addition, engineering application research has also been carried out, and it is recommended that the injection displacement during early construction should not be less than 3 m3/min, and the fracturing viscosity should not be less than 45 mPa·s. The field application effect is good, which verifies the engineering application value of the model.
Enhanced Multiphase Flow Measurement Using Dual Non-Intrusive Techniques and ANN Model for Void Fraction Determination
Authors: Mohammed Shivan , Abdulkareem Lokman , Roshani Gholam Hossein , Eftekhari-Zadeh Ehsan , Haso Ezadin
Published: November 2022

There are many petrochemical industries that need adequate knowledge of multiphase flow phenomena inside pipes. In such industries, measuring the void fraction is considered to be a very challenging task. Thus, various techniques have been used for void fraction measurements. For determining more accurate multiphase flow measurements, this study employed dual non-intrusive techniques, gamma-ray and electrical capacitance sensors. The techniques using such sensors are considered non-intrusive as they do not cause any perturbation of the local structure of the phases’ flow. The first aim of this paper is to analyze both techniques separately for the void fraction data obtained from practical experiments. The second aim is to use both techniques’ data in a neural network model to analyze measurements more efficiently. Accordingly, a new system is configured to combine the two techniques’ data to obtain more precise results than they can individually. The simulations and analyzing procedures were performed using MATLAB. The model shows that using gamma-ray and capacitance-based sensors gives Mean Absolute Errors (MAE) of 3.8% and 2.6%, respectively, while using both techniques gives a lower MAE that is nearly 1%. Consequently, measurements using two techniques have the ability to enhance the multiphase flows’ observation with more accurate features. Such a hybrid measurement system is proposed to be a forward step toward an adaptive observation system within related applications of multiphase flows.
Assessment of Antimicrobial, Anticancer, and Antioxidant Activity of Verthimia iphionoides Plant Extract
Authors: Al-Rimawi Fuad , Imtara Hamada , Khalid Mahmoud , Salah Zaidoun , Parvez Mohammad Khalid , Saleh Asmaa , Al kamaly Omkulthom , Shawki Dahu Christina
Published: November 2022

Verthimia iphionoides extract from Palestine was tested in vitro for its antioxidant, antibacterial, and anticancer activities. Total phenolic content (TPC) and total flavonoid content (TFC) measurements were made concurrently. By using FRAP and DPPH methods, the antioxidant activity were measured spectrophotometrically. By using HPLC-PDA, phenolic and flavonoid compounds of the extract were determined. Results showed strong antioxidant activity of the plant extract revealed by inhibition of stable free radicals (DPPH test) and strong reducing ability (FRAP test). According to spectrophotometric methods for total phenolic compounds and total flavonoids content, the extracts were also found to be rich in polyphenolic compounds and flavonoids. Verthimia iphionoides extract had high antibacterial activity against three bacterial strains (Escherichia coli, Staphylococcus aureus, and Streptococcus aureus), with inhibition zone values of 14 mm, 25 mm, and 27 mm, respectively. Bioactivities were primarily attributed to plants’ abundant phenol-based chemical composition. Additionally, the extract was found to be abundant in phenolic and flavonoids, which improved its reducing activity and capacity to scavenge free radicals. Plant extracts were subjected to HPLC analysis, which identified different flavonoids and phenolic compounds in the extracts.
Tool Wear in Nickel-Based Superalloy Machining: An Overview
Authors: Wang Rui , Yang Dayong , Wang Wei , Wei Furui , Lu Yuwei , Li Yuqi
Published: November 2022

Nickel-based superalloys have been widely used in the aerospace, petrochemical, and marine fields and others because of their good oxidation resistance, corrosion resistance, stability, and reliability at various temperatures. However, as a nickel-based superalloy is a kind of processed material, in the cutting process a large amount of cutting heat is generated due to the interaction between the tool and the workpiece. At the same time, the low thermal conductivity of the workpiece causes a large amount of cutting heat to accumulate at the contact point, resulting in serious tool wear, reduced tool life, frequent tool changes, and other problems, which increase the production cost of the enterprise. This paper introduces the tool wear mechanisms (abrasive wear, adhesive wear, plastic deformation, chemical wear, etc.) in the machining process of nickel-based superalloys and summarizes the research status of failure mechanisms, tool wear optimization, etc. Based on a review of the existing research, it was found that the purpose of adding tool coatings, optimizing tool materials and cutting parameters, or improving the cutting environment is to control the heat during the processing of nickel-based superalloys to improve the tool environment and prolong the service life. The development prospects of tool wear prevention measures in the field of nickel-based alloy machining are also described.
Vapor Overproduction Condition Monitoring in a Liquid–Vapor Ejector
Authors: Sharapov Serhii , Mižáková Jana , Husiev Danylo , Panchenko Vitalii , Ivanov Vitalii , Pavlenko Ivan , Židek Kamil
Published: November 2022

We consider the influence of vapor content in the mixed flow leaving a liquid-vapor ejector on the energy efficiency of a vacuum unit. As shown by numerical studies of liquid-vapor ejectors, this issue is important as vapor overproduction, which accompanies the process of secondary flow ejection, directly impacts the efficiency of the working process of both the liquid-vapor ejector and the vacuum unit as a whole. The greater the degree of vapor overproduction, the greater the load on the vapor phase of the separator, which is part of the vacuum unit. In addition, the liquid phase must be returned to the cycle to ensure the constancy of the mass flow rate of the working fluid of the primary flow. Our numerical study results revealed the rational value of the degree of vapor overproduction at which the efficiency of the liquid–vapor ejector was maximized, and the amount of additional working fluid that needed to enter the cycle of the vacuum unit was minimal. Experimental condition monitoring studies on the liquid–vapor ejector were carried out on plane-parallel transparent models with different flow path geometries. Through experimental studies, we confirmed and adjusted the values of the achievable efficiency of the working process of a liquid–vapor ejector, depending on the degree of vapor overproduction. Using a comparative analysis of liquid–vapor ejectors with different flow path geometries, differences were revealed in their working processes, which consisted of the degree of completion of the mixing of the working media of primary and secondary flows. To determine the feasibility of using liquid–vapor ejectors with different flow path geometries, exergy analysis was performed, resulting in achievable efficiency indicators.
Enhancing Effects of Sludge Biochar on Aerobic Granular Sludge for Wastewater Treatment
Authors: Zhang Xiufang , Liu Yongqiang , Li Jun , Wei Zhuo , Duan Wenyan , Chen Fangyuan
Published: November 2022

Sludge biochar can be used as bio-carrier to enhance aerobic granular sludge, however, its impact on the formation and especially long-term stability of aerobic granules has not been fully investigated. In this paper, aerobic granular sludge was cultivated in two parallel sequencing batch reactors (SBRs), R1 and R2, with and without sludge biochar addition in the activated sludge inoculum, respectively. The sludge characteristics, wastewater treatment performance, and microbial community structure of granular sludge were examined on a 240-day operation, during which aerobic granular sludge in the two reactors experienced dynamic changes including granule formation, maturation, breakage, filamentous proliferation, and recovery. Aerobic granules in R1 with biochar formed two weeks earlier than that in R2, presenting a larger mean size, and higher settling ability and biomass retention in the granule maturation period. Concurrently, aerobic granules in R1 showed higher denitrification ability with over 80% removal efficiency throughout the whole operation period. During the maturation period, the ratio of food to biomass (F/M) in R1 was below 0.5 gCOD/gVSS d while it ranged between 0.5 and 1.0 gCOD/gVSS d in R2 due to lower biomass retention. The elemental analysis showed more Ca and P accumulation in aerobic granular sludge from R1, with 3% Ca and 2.75% P in sludge from R1 and 0.91% Ca and 0.75% P in sludge from R2, respectively. The microbial community in R1 had higher richness, diversity, excretion of extracellular polymer substances (EPSs) and abundance of denitrifying genera than that in R2, supporting its higher stability and denitrification performance. These results demonstrated that aerobic granular sludge formed by using sludge biochar as a carrier for granulation can speed up granule formation, improve denitrification performance, and enhance the long-term stability of aerobic granules. The findings disclosed the enhancing effects of biochar for wastewater treatment by aerobic granular sludge, suggesting the potential of practical application of biochar in aerobic granular sludge-based reactors.
Dynamic Connectedness between Indicators of the Ghana Stock Exchange Returns and Macroeconomic Fundamentals
Authors: Idun Anthony Adu-Asare , Asafo-Adjei Emmanuel , Adam Anokye Mohammed , Isshaq Zangina
Published: November 2022

The performance of the Ghana Stock Exchange (GSE) over the years has been susceptible to both crises and country-specific factors reflected in its macroeconomic fundamentals. Accordingly, the GSE composite index (GSECI) has experienced rapid fluctuations across time, coupled with a declining market capitalisation from a reduction in the number of existing firms. The plunge in the number of firms is partly linked to the banking sector clean-up in 2017, which induced the collapse and consolidation of some financial institutions as well as weaknesses in other macroeconomic variables. This ignites an investigation into whether the synergistic impact of listed firms that represent the financial sector and the soundness of the banking sector measures are dominant factors that could drive or respond to shocks. Hence, the study investigates the lead-lag relationships and degree of integration among two indicators of the GSE—GSECI and GSE financial index (GSEFI), seven banking financial soundness indicators and eight interest rate measures. The wavelet approaches (biwavelet and wavelet multiple) are utilised to address the research problem. The DCC-GARCH connectedness approach is then employed as a robustness check. We found high interconnectedness between the indicators of the GSE and banking sector financial soundness, relative to the interest rates. Notwithstanding, the Treasury bill measures drive the GSE indicators in the short-, and medium-terms. In comparison with the two indicators of the GSE, significant comovements are dominant between the GSEFI and the two forms of selected macroeconomic variables. We advocate that the comovements among the indicators of the GSE, banking sector financial soundness and interest rate measures are heterogeneous and adaptive, especially during crises, but more significant comovements are germane to the GSEFI. The study provides further implications for policy, practice, and theory.
Analyzing the Spatially Heterogeneous Relationships between Nighttime Light Intensity and Human Activities across Chongqing, China
Authors: Wu Jihao , Tu Yue , Chen Zuoqi , Yu Bailang
Published: November 2022

Nighttime light (NTL) intensity is highly associated with the unique footprint of human activities, reflecting the development of socioeconomic and urbanization. Therefore, better understanding of the relationship between NTL intensity and human activities can help extend the applications of NTL remote sensing data. Different from the global effect of human activities on NTL intensity discussed in previous studies, we focused more attention to the local effect caused by the spatial heterogeneity of human activities with the support of the multiscale geographically weighted regression (MGWR) model in this study. In particular, the Suomi National Polar Orbiting Partnership/Visible Infrared Imaging Radiometer Suite (NPP/VIIRS) NTL data within Chongqing, China were taken as example, and the point of interest (POI) data and road network data were adopted to characterize the intensity of human activity type. Our results show that there is significant spatial variation in the effect of human activities to the NTL intensity, since the accuracy of fitted MGWR (adj.R2: 0.86 and 0.87 in 2018 and 2020, respectively; AICc: 4844.63 and 4623.27 in 2018 and 2020, respectively) is better than that of both the traditional ordinary least squares (OLS) model and the geographically weighted regression (GWR) model. Moreover, we found that almost all human activity features show strong spatial heterogeneity and their contribution to NTL intensity varies widely across different regions. For instance, the contribution of road network density is more homogeneous, while residential areas have an obviously heterogeneous distribution which is associated with house vacancy. In addition, the contributions of the commercial event and business also have a significant spatial heterogeneity distribution, but show a distinct decrement when facing the COVID-19 pandemic. Our study successfully explores the relationship between NTL intensity and human activity features considering the spatial heterogeneity, which aims to provide further insights into the future applications of NTL data.
A Direct Method for the Estimation of Top-of-Atmosphere Outgoing Longwave Radiation from Himawari-8/AHI Data
Authors: Zhan Chuan , Jiang Yazhen , Chen Yong , Miao Zuohua , Zeng Xiangyang , Li Jun
Published: November 2022

Top-of-atmosphere (TOA) outgoing longwave radiation (OLR), a key component of the Earth’s energy budget, serves as a diagnostic of the Earth’s climate system response to incoming solar radiation. However, existing products are typically estimated using the traditional two-step method, which may bring extra uncertainties. This paper presents a direct machine learning method to estimate TOA OLR by directly linking Himawari-8/Advanced Himawari Imager (AHI) TOA radiances with TOA OLR determined by Clouds and the Earth’s Radiant Energy System (CERES) and other information, such as the viewing geometry. Models are built separately under clear- and cloudy-sky conditions using a gradient-boosting regression tree. Independent test results show that the root mean square errors (RMSEs) of the clear-sky and cloudy-sky models for estimating instantaneous values are 7.46 W/m2 (3.0%) and 11.61 W/m2 (5.8%), respectively. Daily results are obtained by averaging all the instantaneous results in one day. Intercomparisons of the daily results with CERES TOA OLR data show that the RMSE of the estimated AHI OLR is ~6 W/m2 (3%). The developed high-resolution AHI TOA OLR dataset will be beneficial in analyzing the regional energy budget.
System Structure–Based Drought Disaster Risk Assessment Using Remote Sensing and Field Experiment Data
Authors: Cui Yi , Tang Huiyan , Jin Juliang , Zhou Yuliang , Jiang Shangming , Chen Menglu
Published: November 2022

With the impacts of climate change and human activities, agricultural drought disaster losses have increased remarkably. Drought disaster risk assessment is a prerequisite for formulating disaster reduction strategies and ensuring food security. However, drought disaster risk is a complex system, and quantitative assessment methods reflecting the risk formation mechanism are still rarely reported. This study presented a chain transmission system structure of drought disaster risk, which meant that drought disaster loss risk R was derived from drought hazard H by the transformation of drought disaster vulnerability V. Based on this point, firstly, a drought hazard curve between drought intensity and drought frequency was established using remote sensing data and the copula function. Then, a crop loss calculation approach under various drought events and drought resistance capacity scenarios was achieved by two-season field experiments and the AquaCrop model. Finally, a loss risk curve cluster of “drought frequency–drought resistance capacity–yield loss rate” was proposed by the composition of the above two quantitative relationships. The results of the case study for summer maize in Bengbu City indicated that the average yield loss rate under 19 droughts occurring during the growth period of maize from 1982 to 2017 was 24.51%. High risk happened in 1988, 1992, 1994, 2001, and 2004, with the largest loss rate in 2001, up to 65.58%. Overall, droughts with a return period less than two years occurred frequently during the growth period of summer maize in Bengbu, though the loss risk was still controllable. In conclusion, the results suggest that the loss risk curve provides a new effective method of drought disaster risk quantitative assessment from a physical mechanism perspective, which lays a scientific foundation for decision-making in risk management.
Dual-Constraint Registration LiDAR SLAM Based on Grid Maps Enhancement in Off-Road Environment
Authors: Zhu Hui , Kuang Xinkai , Su Tao , Chen Ziyu , Yu Biao , Li Bichun
Published: November 2022

Aiming at the influence of fewer feature points and dynamic obstacles on location and mapping in off-road environments, we propose a dual-constraint LiDAR-based Simultaneous Localization and Mapping (SLAM) scheme. By abstracting LiDAR registration into two constraints, namely, in-window constraints and out-of-window constraints, the in-window constraints allow our scheme to compromise between accuracy and real-time performance, and out-of-window constraints can exploit optimized variables to provide richer constraint information. The advantages of incremental SLAM map construction can be used to design a variety of map forms. Although the variables outside the window are no longer involved in the optimization, we can use the two-dimensional probability grid map to provide binary semantic information and dynamic weights for the constraints outside the window to enhance the registration accuracy. Finally, we conducted experiments in off-road environment and compared with the mainstream LiDAR SLAM scheme, which can prove that our scheme has more advantages in accuracy.
Remote Sensing Monitoring of Rice and Wheat Canopy Nitrogen: A Review
Authors: Zheng Jie , Song Xiaoyu , Yang Guijun , Du Xiaochu , Mei Xin , Yang Xiaodong
Published: November 2022

Nitrogen(N) is one of the most important elements for crop growth and yield formation. Insufficient or excessive application of N fertilizers can limit crop yield and quality, especially as excessive N fertilizers can damage the environment and proper fertilizer application is essential for agricultural production. Efficient monitoring of crop N content is the basis of precise fertilizer management, and therefore to increase crop yields and improve crop quality. Remote sensing has gradually replaced traditional destructive methods such as field surveys and laboratory testing for crop N diagnosis. With the rapid advancement of remote sensing, a review on crop N monitoring is badly in need of better summary and discussion. The purpose of this study was to identify current research trends and key issues related to N monitoring. It begins with a comprehensive statistical analysis of the literature on remote sensing monitoring of N in rice and wheat over the past 20 years. The study then elucidates the physiological mechanisms and spectral response characteristics of remote sensing monitoring of canopy N. The following section summarizes the techniques and methods applied in remote sensing monitoring of canopy N from three aspects: remote sensing platforms for N monitoring; correlation between remotely sensed data and N status; and the retrieval methods of N status. The influential factors of N retrieval were then discussed with detailed classification. However, there remain challenges and problems that need to be addressed in the future studies, including the fusion of multisource data from different platforms, and the uncertainty of canopy N inversion in the presence of background factors. The newly developed hybrid model integrates the flexibility of machine learning with the mechanism of physical models. It could be problem solving, which has the advantages of processing multi-source data and reducing the interference of confounding factors. It could be the future development direction of crop N inversion with both high precision and universality.
The Inversion of HY-1C-COCTS Ocean Color Remote Sensing Products from High-Latitude Seas
Authors: Li Hao , He Xianqiang , Ding Jing , Bai Yan , Wang Difeng , Gong Fang , Li Teng
Published: November 2022

China’s first operational ocean color satellite sensor, named the Chinese Ocean Color and Temperature Scanner (HY-1C-COCTS), was launched in September 2018 and began to provide operational data in June 2019. However, as a polar orbiting ocean color satellite sensor, HY-1C-COCTS would inevitably encounter regions impacted by large solar zenith angles when observing the high-latitude seas, especially during the winter. The current atmospheric correction algorithm used by ocean color satellite data processing software cannot effectively process observation data with solar zenith angles greater than 70°. This results in a serious lack of effective ocean color product data from high-latitude seas in winter. To solve this problem, this study developed an atmospheric correction algorithm based on a neural network model for use with HY-1C-COCTS data. The new algorithm used HY-1C-COCTS satellite data collected from latitudes greater than 50°N and between April 2020 and April 2021 to establish a direct relationship between the total radiance received by the satellite and the remote sensing reflectance products. The evaluation using the test dataset shows that the inversion accuracy of the new algorithm is relatively high under different solar zenith angles and different HY-1C-COCTS bands (the relative deviation is 3.37%, 7.05%, 5.10%, 5.29%, and 10.06% at 412 nm, 443 nm, 490 nm, 520 nm, and 565 nm, respectively; the relative deviation is 1.07% when the solar zenith angle is large (70~90°)). Cross comparison with MODIS Aqua satellite products shows that the inversion results are consistent. After verifying the accuracy and stability of the algorithm, we reconstructed the remote sensing reflectance dataset from the Arctic Ocean and surrounding high-latitude seas (latitude greater than 50°N) and successfully retrieved chlorophyll-a data and information on other marine ecological parameters.
Decadal Continuous Meteor-Radar Estimation of the Mesopause Gravity Wave Momentum Fluxes over Mohe: Capability Evaluation and Interannual Variation
Authors: Zhou Xu , Yue Xinan , Liu Libo , Yu You , Ding Feng , Ren Zhipeng , Jin Yuyan , Yin Hanlin
Published: November 2022

In the present work, the momentum fluxes of gravity wave (GW) around the mesopause are estimated, using the decadal continuous observations by meteor radar at Mohe (53.5°N, 122.3°E). Applying the Hocking’s (2005) approach with the modified-composite-day (MCD) analysis, the GW momentum fluxes of short-periods (less than 2 h) are estimated month by month. As the first step, several experiments are designed to evaluate the accuracy and uncertainty in the estimation. The results show that Mohe meteor radar has the ability to give reasonable estimations on the GW momentum fluxes at a height of 82–94 km, in which errors are generally less than 5 m2/s2. The uncertainty induced by different angular information of the detected meteor in each month achieves ~2 m2/s2. It is inferred that the variability of the GW momentum fluxes over 2 m2/s2 can be distinguished in the observation. The interannual variation of the estimated GW momentum fluxes show a significant enhancement in 2012, and a depression in 2013, with a fluctuation over ±10 m2/s2 at 82 km. However, no obvious quasi-biennial oscillation (QBO) -like signal has been found in the Lomb–Scargle periodogram.
Precise Wetland Mapping in Southeast Asia for the Ramsar Strategic Plan 2016–24
Authors: Liu Yang , Zhang Huaiqing , Cui Zeyu , Zuo Yuanqing , Lei Kexin , Zhang Jing , Yang Tingdong , Ji Ping
Published: November 2022

A precise distribution map of wetlands can provide basic data of wetland conservation and management for Ramsar parties in each region. In this study, based on the Google Earth Engine (GEE) platform and Sentinel-2 images, the integrated inundation dynamic, phenological, and geographical features for a multi-class tropical wetland mapping method (IPG-MTWM) was used to generate the Southeast Asia wetland cover map (SEAWeC) in 2020, which has a 10 m spatial resolution with 11 wetland types. The overall accuracy (OA) of SEAWeC was 82.52%, which, in comparison with other mappings the SEAWeC, performs well. The results of SEAWeC show that (1) in 2020, the total wetland area in Southeast Asia was 123,268.61 km2, (2) for the category I, the coastal wetlands has the largest area, reaching 58,534.78 km2, accounting for 47.49%, (3) for the category II, the coastal swamp has the largest area, reaching 48,002.66 km2, accounting for 38.94% of the total wetland area in Southeast Asia, and (4) significant difference in wetland rate (WR) between countries in Southeast Asia, in which Singapore has a WR of 6.96%, ranking first in Southeast Asia. The SEAWeC can provide the detailed spatial and type distribution data as basic data for the Southeast Asia to support the Ramsar strategic plan 2016–24.
Above-Ground Biomass Estimation for Coniferous Forests in Northern China Using Regression Kriging and Landsat 9 Images
Authors: Jiang Fugen , Sun Hua , Chen Erxue , Wang Tianhong , Cao Yaling , Liu Qingwang
Published: November 2022

Accurate estimation of forest above-ground biomass (AGB) is critical for assessing forest quality and carbon stocks, which can improve understanding of the vegetation growth processes and the global carbon cycle. Landsat 9, the latest launched Landsat satellite, is the successor and continuation of Landsat 8, providing a highly promising data resource for land cover change, forest surveys, and terrestrial ecosystem monitoring. Regression kriging was developed in the study to improve the AGB estimation and mapping using the Landsat 9 image in Wangyedian forest farm, northern China. Multiple linear regression (MLR), support vector machine (SVM), back propagation neural network (BPNN), and random forest (RF) were used as the original models to predict the AGB trends, and the optimal model was used to overlay the results of kriging interpolation based on the residuals to obtain the new AGB predictions. In addition, Landsat 8 images in Wangyedian were used for comparison and verification with Landsat 9. The results showed that all bands of Landsat 8 and Landsat 9 maintained a high degree of uniformity, with positive correlation coefficients ranging from 0.77 to 0.89 (p < 0.01). RF achieved the highest estimation accuracy among all the original models based on the two data sources. However, kriging regression can significantly reduce the estimation error, with the root mean square error (RMSE) decreasing by 55.4% and 51.1%, for Landsat 8 and Landsat 9, respectively, compared to the original RF. Further, the R2 and the lowest RMSE for Landsat 8 were 0.88 and 16.83 t/ha, while, for Landsat 9, they were 0.87 and 17.91 t/ha. The use of regression kriging combined with Landsat 9 imagery has great potential for achieving efficient and highly accurate forest AGB estimates, providing a new reference for long-term monitoring of forest resource dynamics.