bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic Characteristics of Rubber Reinforced Expansive Soil (ESR) at Positive and Negative Ambient Temperatures
Authors: Lv Jianhang , Yang Zhongnian , Shi Wei , Lu Zhaochi , Zhang Qi , Ling Xianzhang
Published: September 2022

Using tire waste rubber reinforced expansive soil (ESR) can modify its poor engineering characteristics. The damping properties of ESR at different temperatures may vary dramatically. Two kinds of rubber Ra (large particle size) and Rb (small particle size) are mixed with expansive soil according to gradient ratio. The backbone curves, dynamic shear modulus, and damping ratio of expansive soil in varying temperature fields of 20 °C, −5 °C, and −15 °C are investigated. The Hardin-Drnevich model can well fit the backbone curves of ESR specimens in various temperature fields. Dynamic triaxial results show that 5–10% Ra rubber can withstand higher shear stress in all temperature fields; Rb rubber can increase the dynamic shear modulus of expansive soil and reach the peak value with 10% rubber content. The damping ratio can be significantly improved by using 10% Ra rubber at room temperature, while the ESR damping ratio in a temperature field of −5 °C does not change significantly with increasing shear strain or even decreases; Ra increases the damping ratio of expansive soils in the temperature field of 15 °C while small particle size Rb decreases the damping ratio of expansive soils. The experimental results validate the effectiveness of ESR in the frozen soil area. In an engineering sense, local temperature needs to be considered to use an appropriate ESR, which can provide effective seismic isolation and damping.
Molecular Characterization and Biocompatibility of Exopolysaccharide Produced by Moderately Halophilic Bacterium Virgibacillus dokdonensis from the Saltern of Kumta Coast
Authors: Andrew Monic , Jayaraman Gurunathan
Published: September 2022

The use of natural polysaccharides as biomaterials is gaining importance in tissue engineering due to their inherent biocompatibility. In this direction, the present study aims to explore the structure and biocompatibility of the EPS produced by Virgibacillus dokdonensis VITP14. This marine bacterium produces 17.3 g/L of EPS at 96 h of fermentation. The EPS was purified using ion exchange and gel permeation chromatographic methods. The porous web-like structure and elemental composition (C, O, Na, Mg, P, S) of the EPS were inferred from SEM and EDX analysis. AFM analysis revealed spike-like lumps with a surface roughness of 84.85 nm. The zeta potential value of −10 mV indicates the anionic nature of the EPS. Initial molecular characterization showed that the EPS is a heteropolysaccharide composed of glucose (25.8%), ribose (18.6%), fructose (31.5%), and xylose (24%), which are the monosaccharide units in the HPLC analysis. The FTIR spectrum indicates the presence of functional groups/bonds typical of EPSs (O-H, C-H, C-O-H, C-O, S=O, and P=O). The polymer has an average molecular weight of 555 kDa. Further, NMR analysis revealed the monomer composition, the existence of two α- and six β-glycosidic linkages, and the branched repeating unit as → 1)[α-D-Xylp-(1 → 2)-α-D-Glcp-(1 → 6)-β-D-Glcp-(1 → 5)]-β-D-Frup-(2 → 2)[β-D-Xylp-(1 → 4)]-β-D-Xylp-(1 → 6)-β-D-Fruf-(2 → 4)-β-D-Ribp-(1 →. The EPS is thermally stable till 251.4 °C. X-ray diffraction analysis confirmed the semicrystalline (54.2%) nature of the EPS. Further, the EPS exhibits significant water solubility (76.5%), water-holding capacity (266.8%), emulsifying index (66.8%), hemocompatibility (erythrocyte protection > 87%), and cytocompatibility (cell viability > 80% on RAW264.7 and keratinocyte HaCaT cells) at higher concentrations and prolongs coagulation time in APTT and PT tests. Our research unveils the significant biocompatibility of VITP14 EPS for synthesizing a variety of biomaterials.
Electrospun Porous Nanofibers: Pore−Forming Mechanisms and Applications for Photocatalytic Degradation of Organic Pollutants in Wastewater
Authors: Cao Xianyang , Chen Wei , Zhao Ping , Yang Yaoyao , Yu Deng-Guang
Published: September 2022

Electrospun porous nanofibers have large specific surface areas and abundant active centers, which can effectively improve the properties of nanofibers. In the field of photocatalysis, electrospun porous nanofibers can increase the contact area of loaded photocatalytic particles with light, shorten the electron transfer path, and improve photocatalytic activity. In this paper, the main pore−forming mechanisms of electrospun porous nanofiber are summarized as breath figures, phase separation (vapor−induced phase separation, non−solvent−induced phase separation, and thermally induced phase separation) and post−processing (selective removal). Then, the application of electrospun porous nanofiber loading photocatalytic particles in the degradation of pollutants (such as organic, inorganic, and bacteria) in water is introduced, and its future development prospected. Although porous structures are beneficial in improving the photocatalytic performance of nanofibers, they reduce their mechanical properties. Therefore, strategies for improving the mechanical properties of electrospun porous nanofibers are also briefly discussed.
Initiated Chemical Vapor Deposition (iCVD) of Bio-Based Poly(tulipalin A) Coatings: Structure and Material Properties
Authors: Graur Valeria , Mukherjee Adrivit , Sebakhy Khaled O. , Bose Ranjita K.
Published: September 2022

A solvent-free route of initiated chemical vapor deposition (iCVD) was used to synthesize a bio-renewable poly(α-Methylene-γ-butyrolactone) (PMBL) polymer. α-MBL, also known as tulipalin A, is a bio-based monomer that can be a sustainable alternative to produce polymer coatings with interesting material properties. The produced polymers were deposited as thin films on three different types of substrates—polycarbonate (PC) sheets, microscopic glass, and silicon wafers—and characterized via an array of characterization techniques, including Fourier-transform infrared (FTIR), proton nuclear magnetic resonance spectroscopy (1H NMR), ultraviolet visible spectroscopy (UV–vis), differential scanning calorimetry (DSC), size-exclusion chromatography (SEC), and thermogravimetric analysis (TGA). Optically transparent thin films and coatings of PMBL were found to have high thermal stability up to 310 °C. The resulting PMBL films also displayed good optical characteristics, and a high glass transition temperature (Tg~164 °C), higher than the Tg of its structurally resembling fossil-based linear analogue-poly(methyl methacrylate). The effect of monomer partial pressure to monomer saturation vapor pressure (Pm/Psat) on the deposition rate was investigated in this study. Both the deposition rate and molar masses increased linearly with Pm/Psat following the normal iCVD mechanism and kinetics that have been reported in literature.
Recent Advances in Silver Nanoparticles Containing Nanofibers for Chronic Wound Management
Authors: Sabarees Govindaraj , Velmurugan Vadivel , Tamilarasi Ganesan Padmini , Alagarsamy Veerachamy , Raja Solomon Viswas
Published: September 2022

Infections are the primary cause of death from burns and diabetic wounds. The clinical difficulty of treating wound infections with conventional antibiotics has progressively increased and reached a critical level, necessitating a paradigm change for enhanced chronic wound care. The most prevalent bacterium linked with these infections is Staphylococcus aureus, and the advent of community-associated methicillin-resistant Staphylococcus aureus has posed a substantial therapeutic challenge. Most existing wound dressings are ineffective and suffer from constraints such as insufficient antibacterial activity, toxicity, failure to supply enough moisture to the wound, and poor mechanical performance. Using ineffective wound dressings might prolong the healing process of a wound. To meet this requirement, nanoscale scaffolds with their desirable qualities, which include the potential to distribute bioactive agents, a large surface area, enhanced mechanical capabilities, the ability to imitate the extracellular matrix (ECM), and high porosity, have attracted considerable interest. The incorporation of nanoparticles into nanofiber scaffolds constitutes a novel approach to “nanoparticle dressing” that has acquired significant popularity for wound healing. Due to their remarkable antibacterial capabilities, silver nanoparticles are attractive materials for wound healing. This review focuses on the therapeutic applications of nanofiber wound dressings containing Ag-NPs and their potential to revolutionize wound healing.
Functional Properties and Storage Stability of Astaxanthin-Loaded Polysaccharide/Gelatin Blend Films—A Comparative Study
Authors: Łupina Katarzyna , Kowalczyk Dariusz , Kazimierczak Waldemar
Published: September 2022

Edible films were obtained from the aqueous binary 75/25 blends of polysaccharides (carboxymethyl cellulose (CMC), gum Arabic (GAR), octenyl succinic anhydride starch (OSA), and water-soluble soy polysaccharides (WSSP)) and gelatin (GEL) supplemented with increasing concentrations (0, 0.25, 0.5, and 1% w/w) of water-soluble AstaSana (AST) astaxanthin. The AST-loaded films were red and exhibited a grainy microstructure and reduced transparency. The CMC- and WSSP-based films were the best UV-C blockers. After the incorporation of 1% AST, the antiradical activity of the films increased by 1.5 times (~25 percentage points) compared to the controls. The tensile strength (TS) of the CMC-containing films was much higher than those of the other films (36.88–43.04 vs. 2.69–15.62 MPa). AST decreased the TS of the CMC/GEL film (by ~11–14%) but improved the mechanical cohesiveness of the GAR/GEL film (by ~50%). The storage test (at 25 °C and 60 °C, no light access) revealed that the CMC- and GAR-based films exhibited the lowest colour change. Furthermore, at the elevated temperature, the films with higher AST concentration exhibited a better ability to maintain their colour. The WSSP/GEL films were the most prone to darkening and yellowing, possibly due to the Maillard reaction. Moreover, these films had the weakest antiradical activity.
Polystyrene-Impregnated Glulam Resistance to Subterranean Termite Attacks in a Laboratory Test
Authors: Hadi Yusuf Sudo , Hermawan Dede , Abdillah Imam Busyra , Mubarok Mahdi , Arsyad Wa Ode Muliastuty , Pari Rohmah
Published: September 2022

This study aimed to enhance tropical fast-growing tree species’ resistance to subterranean termite (Coptotermes curvignathus) attacks through the manufacturing of polystyrene glued-laminated timber (glulam). Three young tropical wood species, namely manii (Maesopsis eminii), mangium (Acacia mangium), and rubber-wood (Hevea brasiliensis), were cut into laminae. After drying, the laminae were impregnated with styrene monomer, then polymerized using potassium peroxydisulfate as a catalyst and heat. The polystyrene-impregnated laminae were constructed using isocyanate glue and a cold press for three-layered glulam. Untreated or control glulam and solid wood specimens were also prepared. The specimens of each wood species and wood products (solid wood, control glulam, and polystyrene glulam) were exposed to the termite in a laboratory test according to Indonesian standards. The results showed that mangium wood had better resistance to the termite attack than manii and rubber-wood, with both of those woods performing the same. Among the wood products, the glulams were equal and had higher resistance to the termite attack than solid wood. To enhance the termite resistance of polystyrene glulam, we suggest that the polymer loading of polystyrene on each lamina should be increased. In our evaluation of the products’ order of priority, polystyrene glulam emerged as performing best towards subterranean termites attack.
Effects of Phosphorus and Boron Compounds on Thermal Stability and Flame Retardancy Properties of Epoxy Composites
Authors: Hamciuc Corneliu , Vlad-Bubulac Tăchiță , Serbezeanu Diana , Macsim Ana-Maria , Lisa Gabriela , Anghel Ion , Şofran Ioana-Emilia
Published: September 2022

While plastics are regarded as the most resourceful materials nowadays, ranging from countless utilities including protective or decorating coatings, to adhesives, packaging materials, electronic components, paintings, furniture, insulating composites, foams, building blocks and so on, their critical limitation is their advanced flammability, which in fire incidents can result in dramatic human fatalities and irreversible environmental damage. Herein, epoxy-based composites with improved flame-resistant characteristics have been prepared by incorporating two flame retardant additives into epoxy resin, namely 6-(hydroxy(phenyl)methyl)-6H-dibenzo[c,e][1,2]oxaphosphinine-6-oxide (PFR) and boric acid (H3BO3). The additional reaction of 9,10-dihydro-oxa-10-phosphophenanthrene-10-oxide (DOPO) to the carbonyl group of benzaldehyde yielded PFR, which was then used to prepare epoxy composites having a phosphorus content ranging from 1.5 to 4 wt%, while the boron content was 2 wt%. The structure, morphology, thermal stability and flammability of resulted epoxy composites were investigated by FTIR spectroscopy, scanning electron microscopy (SEM), thermogravimetric analysis, differential scanning calorimetry, and microscale combustion calorimetry (MCC). Thermogravimetric analysis indicated that the simultaneous incorporation of PFR and H3BO3 improved the thermal stability of the char residue at high temperatures. The surface morphology of the char residues, studied by SEM measurements, showed improved characteristics in the case of the samples containing both phosphorus and boron atoms. The MCC tests revealed a significant reduction in flammability as well as a significant decrease in heat release capacity for samples containing both PFR and H3BO3 compared to the neat epoxy thermoset.
Comparative Study of Friction and Wear Performance of PEK, PEEK and PEKK Binders in Tribological Coatings
Authors: Pedroso Judith M. , Enger Marco , Bandeira Pedro , Magalhães Fernão D.
Published: September 2022

Tribological coatings are widely used in industry, particularly when the conventional oil lubrication of sliding surfaces has to be replaced by maintenance-free contacts. This work studies the tribological performance of waterborne tribological coatings based on three binders of the polyaryletherketone (PAEK) family: polyetherketone (PEK), PEEK, and polyetherketoneketone (PEKK). Even though PEEK is a well-known commercial solution for this type of tribological coatings, PEK and PEKK have never been studied in such a context. PTFE particles were added to all coatings as a solid lubricant. High thermal resistance of the binder materials was confirmed, with decomposition starting above 550 °C, under either N2 or O2 atmosphere. XRD analysis showed that PEK and PEEK are semi-crystalline after being subjected to the coating curing conditions, while PEKK is amorphous. The coatings were successfully applied with thicknesses of 20–30 µm. Tribological measurements showed that the PEK-based coating possesses a coefficient of friction (COF) of 0.08 under high load and pressure conditions (hertzian point contact), which is lower than the reference PEEK-based coating (around 0.11). The PEKK-based coating showed an impressive wear resistance with almost no wear measured compared to the 105 µm wear obtained for PEEK-based coating, while showing a similar COF. These results suggest that PEK and PEKK seem to be interesting alternatives to PEEK and should be further studied for use in tribological coatings.
Preparation, Characterization, and Bio Evaluation of Fatty N- Hexadecanyl Chitosan Derivatives for Biomedical Applications
Authors: Mansour Hanaa , El-Sigeny Samia , Shoman Sarah , Abu-Serie Marwa M. , Tamer Tamer M.
Published: September 2022

The objective of this study was to improve the antibacterial activities of chitosan via N-alkyl substitution using 1-bromohexadecane. Mono and di substitution (Mono-NHD-Ch and Di-NHD-Ch) were prepared and characterized using FT-IR, HNMR, TGA, DSC, and SEM. Elemental analysis shows an increase in the C/N ratio from 5.45 for chitosan to 8.63 for Mono-NHD-Ch and 10.46 for Di-NHD-Ch. The antibacterial properties were evaluated against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus cereus. In the examined microorganisms, the antibacterial properties of the novel alkyl derivatives increased substantially higher than chitosan. The minimum inhibitory concentration (MIC) of Mono-NHD-Ch and Di-NHD-Ch was perceived at 50 μg/mL against tested microorganisms, except for B. cereus. The MTT test was used to determine the cytotoxicity of the produced materials, which proved their safety to fibroblast cells. The findings suggest that the new N-Alkyl chitosan derivatives might be used as antibacterial alternatives to pure chitosan in wound infection treatments.
Polylactic Acid–Glass Fiber Composites: Structural, Thermal, and Electrical Properties
Authors: Klaser Teodoro , Balen Luka , Skoko Željko , Pavić Luka , Šantić Ana
Published: September 2022

The aim of this study is to investigate the influence of different glass fibers made of commercial silicate, borosilicate, and laboratory-made iron–phosphate compositions, on the preparation of polylactic acid (PLA) composites and their structural and physical properties. The thermal, structural, and electrical properties of prepared PLA–glass fiber composites were studied using differential scanning calorimetry, X-ray diffraction, microscopy, and impedance spectroscopy. The structural as well as morphological, thermal, and electrical properties of all PLA–glass composites were found to be very similar and independent of the composition and aspect ratio of glass fibers. All types of glass fibers improve mechanical properties, increase thermal stability, and decrease the electrical conductivity of PLA, thereby producing mechanical strong electrically insulating composite material with potential in various applications.
Ultrasonic Film Rehydration Synthesis of Mixed Polylactide Micelles for Enzyme-Resistant Drug Delivery Nanovehicles
Authors: Stepanova Darya A. , Pigareva Vladislava A. , Berkovich Anna K. , Bolshakova Anastasia V. , Spiridonov Vasiliy V. , Grozdova Irina D. , Sybachin Andrey V.
Published: September 2022

A facile technique for the preparation of mixed polylactide micelles from amorphous poly-D,L-lactide-block-polyethyleneglycol and crystalline amino-terminated poly-L-lactide is described. In comparison to the classical routine solvent substitution method, the ultrasonication assisted formation of polymer micelles allows shortening of the preparation time from several days to 15–20 min. The structure and morphology of mixed micelles were analyzed with the assistance of electron microscopy, dynamic and static light scattering and differential scanning calorimetery. The resulting polymer micelles have a hydrodynamic radius of about 150 nm and a narrow size distribution. The average molecular weight of micelles was found to be 2.1 × 107 and the aggregation number was calculated to be 6000. The obtained biocompatible particles were shown to possess low cytotoxicity, high colloid stability and high stability towards enzymatic hydrolysis. The possible application of mixed polylactide micelles as drug delivery vehicles was studied for the antitumor hydrophobic drug paclitaxel. The lethal concentration (LC50) of paclitaxel encapsulated in polylactide micelles was found to be 42 ± 4 µg/mL—a value equal to the LC50 of paclitaxel in the commercial drug Paclitaxel-Teva.
Bio-Based Healable 2K PU Textile Coating for Durable Applications
Authors: De Smet David , Vanneste Myriam
Published: September 2022

A biobased healable 2K polyurethane (PU) coating incorporating a Schiff base was synthesized and applied as a thin coating on textiles. The Schiff base, made out of cystine and vanillin, contained reversible imine and disulfide bonds and was used as a chain extender in PU synthesis. The FT-IR analysis indicated the successful incorporation of the Schiff base in the PU backbone. Compared with control PU coatings, the healable bio-based PU coating with the Schiff base showed very good healing properties using heat as external stimuli: a healing recovery of 75% was obtained after applying a 2 N scratch and complete recovery of the resistance to hydrostatic pressure. SEM analysis revealed complete closure of the scratch after healing for 30 min at 90 °C. The healing properties are attributed to the synergy of the dual-dynamic metatheses of the imine and disulfide bonds.
Experimental Research on Bonded Anchorage of Carbon Fiber Reinforced Polymer Prestressed Strands
Authors: Jia Liqiang , Wang Bo , Tafsirojjaman T.
Published: September 2022

Aiming at the problems of a large number of corrosion and fatigue damage of the current prestressed steel strands, this paper adopts carbon fiber-reinforced composite (CFRP) strand with better corrosion resistance and fatigue resistance and uses it in concrete structures. The bond anchorage is usually used to anchor CFRP tension members, which bonds the CFRP through the binding medium. Through experimental research on the CFRP strand bond anchorage, the inner taper of the CFRP prestressed strand cone was anchored and the influence of different anchor lengths and bonding media on the anchorage performance was determined. The test results demonstrate that the taper of the conical anchorage described in this paper is a key factor affecting its anchorage performance and increasing the inner taper within a certain range is beneficial to improving the anchorage performance of the conical anchorage. The bonded anchorage of the CFRP prestressed strand with a 200 mm anchor is the most reliable and efficient, as the taper of the 200 mm anchor is the largest. The average anchoring efficiency coefficient of the 200 mm anchor was 96.4%, which is 3.7% and 2.6% higher than the average anchoring efficiency coefficient of 220 mm and 250 mm anchors, respectively. The anchoring efficiency of the anchor is also high (94.1%) when the epoxy resin mortar is used as the bonding medium. Moreover, after an appropriate amount of quartz sand is added to the epoxy resin, the overall comprehensive performance of the anchor can be improved to a certain extent and the stress of the CFRP strand can be improved. The coupling between ultra-high-performance concrete dry mix (UHPC-GJL) and CFRP strand materials is not suitable for UHPC-GJL being used, as its binding medium as the average anchoring efficiency coefficient is only 44.5% when UHPC-GJL is used as the anchor bonding medium.
Effect of Curing Modes on the Mechanical Properties of Commercial Dental Resin-Based Composites: Comparison between Different LEDs and Microwave Units
Authors: Vermudt Alef , Kuga Milton Carlos , Besegato João Felipe , Oliveira Eliane Cristina Gulin de , Leandrin Thaís Piragine , Só Marcus Vinicius Reis , Moraes João Carlos Silos , Pereira Jefferson Ricardo
Published: September 2022

Resin-based composites (RBCs) have transformed restorative dentistry and its procedures. However, the characteristics of RBCs have been modified over the years to enhance the physical and chemical properties of the materials. This context raises the need for studies that evaluate whether the properties of the RBCs that are commercially available are clinically adequate with different curing modes. This study aimed to evaluate the mechanical behavior of commercial RBCs after undergoing different curing modes. Twenty-three RBCs of different classes were evaluated. For curing the specimens, a microwave (BMS45, Brastemp) (for 3 min at 450 W) and three LED units were used: an Emitter A Fit (Schuster (second generation)) (light-curing for 15 s with an irradiance of 1250 mW/cm2), VALO (Ultradent (third generation)) (light-curing for 15 s with an irradiance of 1100 mW/cm2), and Emitter Now Duo (Schuster (second generation)) (light-curing for 15 s with an irradiance of 1100 mW/cm2). A total of 670 RBC specimens of 8 mm in diameter and 1 mm in depth were obtained. Afterward, a biaxial flexure strength test was performed until the failure of the specimens, using a universal testing machine set at a speed of 0.5 mm/min. The same specimens were subjected to infrared spectroscopy for evaluating the degree of conversion. Tukey’s test was used for multiple comparisons at a significance level of 5%. The light-curing mode did not affect the flexure strength of the RBCs (p > 0.05), but the type and shade of RBCs did so (p < 0.05). In conclusion, the type of RBC directly interferes with the mechanical behavior of the material. However, the curing modes within the same RBC did not change the mechanical properties.
Two-Step Optimal-Setting Control for Reagent Addition in Froth Flotation Based on Belief Rule Base
Authors: Lu Fanlei , Gui Weihua , Yang Chunhua , Wang Xiaoli
Published: September 2022

Reagent addition is an important operation in the froth flotation process. In most plants, it is manually regulated according to the operator’s experience, by observing the surface features of the froth. Due to the drawbacks of manual operation, large fluctuations in the process are common, resulting in unexpected process indexes. Thus, we investigated the relationship between reagent addition, feed conditions (including ore properties, slurry density, and slurry flow rate), and froth image features based on the mechanism of froth flotation and production technology of gold-antimony flotation. Then, we proposed a two-step optimal-setting control strategy for reagent addition, which included a basic dosage pre-setting model and a feedback reagent addition compensation model. According to operating conditions and ore properties, the pre-setting model was developed using a belief rule base (BRB) method based on an evidential reasoning approach (RIMER), which could effectively address the uncertainties of operator experience and historical data. The model parameters of the BRB were then optimized using a state transition algorithm (STA). In terms of the offsets of the froth image features, the feedback compensation model using rule-based reasoning (RBR) was built. Simulation results using a STA-optimized BRB, GA-optimized BRB, least squares support vector machine (LSSVM), and artificial neural network (ANN) were compared. Finally, industrial test results confirmed that the reagent addition system based on the proposed method could satisfy the requirements for automatic reagent addition in an industrial production environment. This is of great significance for improving the production efficiency of flotation plants.
Computer-Guided Surgery for Dental Implant Placement: A Systematic Review
Authors: Araujo-Corchado Elena , Pardal-Peláez Beatriz
Published: September 2022

Implant therapy is currently the treatment of choice for the replacement of missing teeth. Correct implant positioning is of vital importance. To this end, radiographic techniques providing 3D information and guided surgery techniques, both static and dynamic, have been developed. The primary objective of this work is to study whether placing dental implants in partially edentulous patients with guided surgery techniques results in less, equal or greater precision than placing them freehand. The secondary objectives are to gain an understanding of the advantages and disadvantages, indications, limitations, and complications of this type of surgery. A literature search was performed in Pubmed and BVS, and six randomized clinical trials meeting the marked inclusion criteria were included. The different guided surgery techniques were compared with each other and with the traditional method. Freehand surgery was found to be the least accurate, as the implants placed with this technique showed the largest deviations between the planned position and the final position, both when calculating the global (3D) deviation and when measuring the deviation in each of the axes (vertical, mesio-distal, bucco-lingual and lateral), and the angular deviation and voxel overlap. In contrast, the most accurate surgeries were fully guided and half-guided, with the smallest deviations between the planned and final implant position. With any guided surgery technique, more precise implant positioning is achieved than with freehand placement. Advantages include reduced trauma and surgery time; disadvantages include reduced primary implant stability and higher cost. This type of surgery is more indicated in cases of critical anatomy, but may encounter limitations in terms of cost, degree of buccal opening, visibility and adjustment of the guides and the need for prior familiarization with the procedure. Nevertheless, this surgical technique reduces the complication rate.
Khmer Nuns and Filial Debts: Buddhist Intersections in Contemporary Cambodia
Authors: Walker Trent
Published: September 2022

Cambodian Buddhist nuns, including the white-robed ṭūn jī, occupy a fraught confluence of competing cultural and religious narratives. Chief among these narratives is gratitude to mothers, among the most powerful structuring forces in Khmer Buddhist culture. By ordaining as nuns, Khmer women break no explicit moral rules, but violate implicit conventions to bear children for their husbands and care for their parents in old age. To explore how this tension plays out in the lives of individual nuns, I draw on public statements and social media posts of two of the most prominent nuns in Cambodia today, Chea Silieng and Heng Kosorl. The two nuns have taken a divergent approach to filial debts, with Silieng emphasizing freedom from her birth family, husband, and children and Kosorl frequently posting about acts of devotion to her parents and grandparents. Both approaches reveal the profoundly gendered dimensions of filial piety and the complex intersection of such narratives with the growing stature of nuns as Buddhist leaders and teachers in Cambodia.
Orientation on ‘Visions of the Good’: A Narrative Analysis of Life Stories of Patients with Personality Disorders
Authors: de Kubber Sylvie P. , Steen Angelien , Schuhmann Carmen , Braam Arjan W.
Published: September 2022

Persons with a diagnosis of personality disorder struggle to experience meaning in life. This article explores how meaning in life of patients with personality disorder changes during intensive psychotherapy. In a qualitative study, life stories of nineteen Dutch patients receiving intensive psychotherapy, written both before and after treatment, were analyzed using holistic content analysis. Here, meaning in life was understood and operationalized in terms of the concept of orientation towards visions of the good by philosopher Charles Taylor. The findings suggest that patients experience both positive and negative shifts concerning meaning in life. On the one hand, in comparison to the first life stories, there is more awareness and insight about the way the ‘good’ is missing in the second life stories. On the other hand, there are more descriptions about being vulnerable, guilty or ashamed, whereas particular sources of meaning are missing.
An Accurate Maritime Radio Propagation Loss Prediction Approach Employing Neural Networks
Authors: Shen Shankun , Zhang Wei , Zhang Hangkai , Ren Qiang , Zhang Xin , Li Yimin
Published: September 2022

The radio propagation loss prediction model is essential for maritime communication. The oceanic tropospheric duct is much more complicated than the atmospheric structure on land due to the rough sea surface influence, and it leads to difficulties in loss prediction. Classical radio wave propagation loss prediction models are either based on complicated electromagnetic wave theories or rely on empirical data. Consequently, they suffer from low accuracy and a limited range of application. To address this issue, a novel maritime propagation loss prediction approach is proposed, which fully exploits the data for training. In this new approach, 3D sea surface contour profiles are generated based on the Pierson–Moskowitz spectrum theory and the direction expansion formula Stereo Wave Observation Program (SWOP), by sweeping the parameters. The full-wave propagation procedure of radio signals over the sea surface is simulated by commercial EM analysis software CST Studio Suite. Based on the large quantity of simulated data, the BP neural network is employed to fit the radio propagation loss and obtain the sea surface radio wave propagation prediction model. Other classical machine learning methods are also compared to validate the proposed approach. Traditional empirical model construction relies on observation data. This approach, for the first time, proposed an automatic scheme which covers the whole procedure from the data generation to prediction model training. It avoids the requirements for on-site observation, as well as significantly decreases the cost of experiments. The application scope of the prediction model such as propagation distance range and working frequency range could be adaptive through adjustments for simulated sea size and simulated working frequency. This approach is validated to save 99% of prediction time in comparison with the full-wave simulations. The prediction model trained via our proposed method could obtain the coefficient of determination R2 which is over 0.92, demonstrating the superiority of this method.
Characterization of an Active Fault through a Multiparametric Investigation: The Trecastagni Fault and Its Relationship with the Dynamics of Mt. Etna Volcano (Sicily, Italy)
Authors: Alparone Salvatore , Bonforte Alessandro , Gambino Salvatore , Grassi Sabrina , Guglielmino Francesco , Latino Federico , Morreale Gabriele , Patti Graziano , Privitera Laura , Obrizzo Francesco , Ursino Andrea , Imposa Sebastiano
Published: September 2022

The Trecastagni Fault (TF) is an important tectonic structure in the middle-lower southern flank of Mt. Etna volcano. It is characterised by evident morphological slopes with normal dip-slip ruptures that directly affect roads and buildings. The TF plays a key role in the complex framework of the volcano dynamics since it represents part of the southern boundary of the unstable sector. Seismic surveys have been performed on three different areas of the fault to gain insights into the seismic stratigraphic structure of the subsoil. We considered the seismic activity of a sector of the territory affecting the surface evidence of the Trecastagni Fault in the period between 1980 and 2021 in order to highlight the main seismic release and define the space–time distribution of seismicity. Most of the seismicity is located in the north-western portion, while the central and southern sectors are characterised by low seismic activity. The strongest earthquakes occur mainly within the first 5 km of depth in the form of swarms and/or isolated shocks. Ground deformation techniques (levelling, In-SAR and two continuous extensometers) evidence a continuous aseismic slip of the TF that is interrupted by short accelerations accompanied by shallow seismicity. The Trecastagni Fault dynamics are strictly linked to magma pressurisation and intrusive episodes of Mt. Etna that induce additional stress and promote its slip along the fault plane. Multidisciplinary data analysed in this work, evidenced the dual behaviour of the fault, from aseismic creep to stick-slip, and the relation with magmatic activity, also suggesting the time delay in the response of the fault after the intense stress induced by dyke intrusion.
Object-Oriented Canopy Gap Extraction from UAV Images Based on Edge Enhancement
Authors: Xia Jisheng , Wang Yutong , Dong Pinliang , He Shijun , Zhao Fei , Luan Guize
Published: September 2022

Efficient and accurate identification of canopy gaps is the basis of forest ecosystem research, which is of great significance to further forest monitoring and management. Among the existing studies that incorporate remote sensing to map canopy gaps, the object-oriented classification has proved successful due to its merits in overcoming the problem that the same object may have different spectra while different objects may have the same spectra. However, mountainous land cover is unusually fragmented, and the terrain is undulating. One major limitation of the traditional methods is that they cannot finely extract the complex edges of canopy gaps in mountainous areas. To address this problem, we proposed an object-oriented classification method that integrates multi-source information. Firstly, we used the Roberts operator to obtain image edge information for segmentation. Secondly, a variety of features extracted from the image objects, including spectral information, texture, and the vegetation index, were used as input for three classifiers, namely, random forest (RF), support vector machine (SVM), and k-nearest neighbor (KNN). To evaluate the performance of this method, we used confusion matrices to assess the classification accuracy of different geo-objects. Then, the classification results were screened and verified according to the area and height information. Finally, canopy gap maps of two mountainous forest areas in Yunnan Province, China, were generated. The results show that the proposed method can effectively improve the segmentation quality and classification accuracy. After adding edge information, the overall accuracy (OA) of the three classifiers in the two study areas improved to more than 90%, and the classification accuracy of canopy gaps reached a high level. The random forest classifier obtained the highest OA and Kappa coefficient, which could be used for extracting canopy gap information effectively. The research shows that the combination of the object-oriented method integrating multi-source information and the RF classifier provides an efficient and powerful method for extracting forest gaps from UAV images in mountainous areas.
Deep Learning-Based Automatic Extraction of Cyanobacterial Blooms from Sentinel-2 MSI Satellite Data
Authors: Yan Kai , Li Junsheng , Zhao Huan , Wang Chen , Hong Danfeng , Du Yichen , Mu Yunchang , Tian Bin , Xie Ya , Yin Ziyao , Zhang Fangfang , Wang Shenglei
Published: September 2022

Cyanobacterial harmful algal blooms (CyanoHABs) in inland water have emerged as a major global environmental challenge. Although satellite remote sensing technology has been widely used to monitor CyanoHABs, there are also some automatic extraction methods of CyanoHABs based on spectral indices (such as gradient mode, fixed threshold, and the Otsu method, etc.), the accuracy is generally not very high. This study developed a high-precision automatic extraction model for CyanoHABs using a deep learning (DL) network based on Sentinel-2 multi-spectral instrument (MSI) data of Chaohu Lake, China. First, we generated the CyanoHABs “ground truth” dataset based on visual interpretation. Thereafter, we trained the CyanoHABs extraction model based on a DL image segmentation network (U-Net) and extracted CyanoHABs. Then, we compared three previous automatic CyanoHABs extraction methods based on spectral index threshold segmentation and evaluated the accuracy of the results. Based on “ground truth”, at the pixel level, the F1 score and relative error (RE) of the DL model extraction results are 0.90 and 3%, respectively, which are better than that of the gradient mode (0.81,40%), the fixed threshold (0.81, 31%), and the Otsu method (0.53, 62%); at CyanoHABs area level, the R2 of the scatter fitting between DL model result and the “ground truth” is 0.99, which is also higher than the other three methods (0.90, 0.92, 0.84, respectively). Finally, we produced the annual CyanoHABs frequency map based on DL model results. The frequency map showed that the CyanoHABs on the northwest bank are significantly higher than in the center and east of Chaohu Lake, and the most serious CyanoHABs occurred in 2018 and 2019. Furthermore, CyanoHAB extraction based on this model did not cause cloud misjudgment and exhibited good promotion ability in Taihu Lake, China. Hence, our findings indicate the high potential of the CyanoHABs extraction model based on DL in further high-precision and automatic extraction of CyanoHABs from large-scale water bodies.
Absolute Accuracy Assessment of Lidar Point Cloud Using Amorphous Objects
Authors: Kim Minsu , Stoker Jason , Irwin Jeffrey , Danielson Jeffrey , Park Seonkyung
Published: September 2022

The accuracy assessment of airborne lidar point cloud typically estimates vertical accuracy by computing RMSEz (root mean square error of the z coordinate) from ground check points (GCPs). Due to the low point density of the airborne lidar point cloud, there is often not enough accurate semantic context to find an accurate conjugate point. To advance the accuracy assessment in full three-dimensional (3D) context, geometric features, such as the three-plane intersection point or two-line intersection point, are often used. Although the point density is still low, geometric features are mathematically modeled from many points. Thus, geometric features provide a robust determination of the intersection point, and the point is considered as a GCP. When no regular built objects are available, we describe the process of utilizing features of irregular shape called amorphous natural objects, such as a tree or a rock. When scanned to a high-density point cloud, an amorphous natural object can be used as ground truth reference data to estimate 3D georeferencing errors of the airborne lidar point cloud. The algorithm to estimate 3D accuracy is the optimization that minimizes the sum of the distance between the airborne lidar points to the ground scanned data. The search volume partitioning was the most important procedure to improve the computational efficiency. We also performed an extensive study to address the external uncertainty associated with the amorphous object method. We describe an accuracy assessment using amorphous objects (108 trees) spread over the project area. The accuracy results for ∆x, ∆y, and ∆z obtained using the amorphous object method were 3.1 cm, 3.6 cm, and 1.7 cm RMSE, along with a mean error of 0.1 cm, 0.1 cm, and 4.5 cm, respectively, satisfying the accuracy requirement of U.S. Geological Survey lidar base specification. This approach shows strong promise as an alternative to geometric feature methods when artificial targets are scarce. The relative convenience and advantages of using amorphous targets, along with its good performance shown here, make this amorphous object method a practical way to perform 3D accuracy assessment.
A Mixed Methods Approach for Fuel Characterisation in Gorse (Ulex europaeus L.) Scrub from High-Density UAV Laser Scanning Point Clouds and Semantic Segmentation of UAV Imagery
Authors: Hartley Robin J. L. , Davidson Sam J. , Watt Michael S. , Massam Peter D. , Aguilar-Arguello Samuel , Melnik Katharine O. , Pearce H. Grant , Clifford Veronica R.
Published: September 2022

The classification and quantification of fuel is traditionally a labour-intensive, costly and often subjective operation, especially in hazardous vegetation types, such as gorse (Ulex europaeus L.) scrub. In this study, unmanned aerial vehicle (UAV) technologies were assessed as an alternative to traditional field methodologies for fuel characterisation. UAV laser scanning (ULS) point clouds were captured, and a variety of spatial and intensity metrics were extracted from these data. These data were used as predictor variables in models describing destructively and non-destructively sampled field measurements of total above ground biomass (TAGB) and above ground available fuel (AGAF). Multiple regression of the structural predictor variables yielded correlations of R2 = 0.89 and 0.87 for destructively sampled measurements of TAGB and AGAF, respectively, with relative root mean square error (RMSE) values of 18.6% and 11.3%, respectively. The best metrics for non-destructive field-measurements yielded correlations of R2 = 0.50 and 0.49, with RMSE values of 40% and 30.8%, for predicting TAGB and AGAF, respectively, indicating that ULS-derived structural metrics offer higher levels of precision. UAV-derived versions of the field metrics (overstory height and cover) predicted TAGB and AGAF with R2 = 0.44 and 0.41, respectively, and RMSE values of 34.5% and 21.7%, demonstrating that even simple metrics from a UAV can still generate moderate correlations. In further analyses, UAV photogrammetric data were captured and automatically processed using deep learning in order to classify vegetation into different fuel categories. The results yielded overall high levels of precision, recall and F1 score (0.83 for each), with minimum and maximum levels per class of F1 = 0.70 and 0.91. In conclusion, these ULS-derived metrics can be used to precisely estimate fuel type components and fuel load at fine spatial resolutions over moderate-sized areas, which will be useful for research, wildfire risk assessment and fuel management operations.
A Low-Altitude Remote Sensing Inspection Method on Rural Living Environments Based on a Modified YOLOv5s-ViT
Authors: Wang Chunshan , Sun Wei , Wu Huarui , Zhao Chunjiang , Teng Guifa , Yang Yingru , Du Pengfei
Published: September 2022

The governance of rural living environments is one of the important tasks in the implementation of a rural revitalization strategy. At present, the illegal behaviors of random construction and random storage in public spaces have seriously affected the effectiveness of the governance of rural living environments. The current supervision on such problems mainly relies on manual inspection. Due to the large number and wide distribution of rural areas to be inspected, this method is limited by obvious disadvantages, such as low detection efficiency, long-time spending, and huge consumption of human resources, so it is difficult to meet the requirements of efficient and accurate inspection. In response to the difficulties encountered, a low-altitude remote sensing inspection method on rural living environments was proposed based on a modified YOLOv5s-ViT (YOLOv5s-Vision Transformer) in this paper. First, the BottleNeck structure was modified to enhance the multi-scale feature capture capability of the model. Then, the SimAM attention mechanism module was embedded to intensify the model’s attention to key features without increasing the number of parameters. Finally, the Vision Transformer component was incorporated to improve the model’s ability to perceive global features in the image. The testing results of the established model showed that, compared with the original YOLOv5 network, the Precision, Recall, and mAP of the modified YOLOv5s-ViT model improved by 2.2%, 11.5%, and 6.5%, respectively; the total number of parameters was reduced by 68.4%; and the computation volume was reduced by 83.3%. Relative to other mainstream detection models, YOLOv5s-ViT achieved a good balance between detection performance and model complexity. This study provides new ideas for improving the digital capability of the governance of rural living environments.
Structure Tensor-Based Infrared Small Target Detection Method for a Double Linear Array Detector
Authors: Gao Jinyan , Wang Luyuan , Yu Jiyang , Pan Zhongshi
Published: September 2022

The paper focuses on the mathematical modeling of a new double linear array detector. The special feature of the detector is that image pairs can be generated at short intervals in one scan. After registration and removal of dynamic cloud edges in each image, the image differentiation-based change detection method in the temporal domain is proposed to combine with the structure tensor edge suppression method in the spatial domain. Finally, experiments are conducted, and our results are compared with theoretic analyses. It is found that a high signal-to-clutter ratio (SCR) of camera input is required to obtain an acceptable detection rate and false alarm rate in real scenes. Experimental results also show that the proposed cloud edge removal solution can be used to successfully detect targets with a very low false alarm rate and an acceptable detection rate.