bluuebunny/crossref_metadata_2025 huggingface dataset:
Current Management of Acute Severe Ulcerative Colitis: New Insights on the Surgical Approaches
Authors: Lauricella Sara , Brucchi Francesco , Cavalcoli Federica , Rausa Emanuele , Cassini Diletta , Miccini Michelangelo , Vitellaro Marco , Cirocchi Roberto , Costa Gianluca
Published: May 2024

Acute severe ulcerative colitis (ASUC) is a life-threatening medical emergency with considerable morbidity. Despite recent advances in medical IBD therapy, colectomy rates for ASUC remain high. A scoping review of published articles on ASUC was performed. We collected data, such as general information of the disease, diagnosis and initial assessment, and available medical and surgical treatments focusing on technical aspects of surgical approaches. The most relevant articles were considered in this scoping review. The management of ASUC is challenging; currently, personalized treatment for it is unavailable. Sequential medical therapy should be administrated, preferably in high-volume IBD centers with close patient monitoring and indication for surgery in those cases with persistent symptoms despite medical treatment, complications, and clinical worsening. A total colectomy with end ileostomy is typically performed in the acute setting. Managing rectal stump is challenging, and all individual and technical aspects should be considered. Conversely, when performing elective colectomy for ASUC, a staged surgical procedure is usually preferred, thus optimizing the patients’ status preoperatively and minimizing postoperative complications. The minimally invasive approach should be selected whenever technically feasible. Robotic versus laparoscopic ileal pouch–anal anastomosis (IPAA) has shown similar outcomes in terms of safety and postoperative morbidity. The transanal approach to ileal pouch–anal anastomosis (Ta-IPAA) is a recent technique for creating an ileal pouch–anal anastomosis via a transanal route. Early experiences suggest comparable short- and medium-term functional results of the transanal technique to those of traditional approaches. However, there is a need for additional comparative outcomes data and a better understanding of the ideal training and implementation pathways for this procedure. This manuscript predominantly explores the surgical treatment of ASUC. Additionally, it provides an overview of currently available medical treatment options that the surgeon should reasonably consider in a multidisciplinary setting.
A Sensor to Monitor Soil Moisture, Salinity, and Temperature Profiles for Wireless Networks
Authors: Chavanne Xavier , Frangi Jean-Pierre
Published: May 2024

This article presents a wireless in situ sensor designed to continuously monitor profiles of parameters in porous media, such as soil moisture, salinity, and temperature. A review of existing in situ soil sensors reveals that it is the only device capable of measuring the complex permittivity of the medium, allowing for conversions into moisture and salinity that are independent of the instrument. Flow perturbation and invasiveness have also been minimized to maintain good representativeness. Plans include autonomous networks of such sensors, facilitated by the use of the recent radio mode LoRaWAN and cost optimizations for series production. Costs were reduced through electronic simplification and integration, and the use of low-cost modular sensing parts in soil, while still maintaining high measurement quality. A complete set of sensor data recorded during a three-month trial is also presented and interpreted.
A Learning-Based Energy-Efficient Device Grouping Mechanism for Massive Machine-Type Communication in the Context of Beyond 5G Networks
Authors: Boisguene Rubbens , Althamary Ibrahim , Huang Chih-Wei
Published: May 2024

With the increasing demand for high data rates, low delay, and extended battery life, managing massive machine-type communication (mMTC) in the beyond 5G (B5G) context is challenging. MMTC devices, which play a role in developing the Internet of Things (IoT) and smart cities, need to transmit short amounts of data periodically within a specific time frame. Although blockchain technology is utilized for secure data storage and transfer while digital twin technology provides real-time monitoring and management of the devices, issues such as constrained time delays and network congestion persist. Without a proper data transmission strategy, most devices would fail to transmit in time, thus defying their relevance and purpose. This work investigates the problem of massive random access channel (RACH) attempts while emphasizing the energy efficiency and access latency for mMTC devices with critical missions in B5G networks. Using machine learning techniques, we propose an attention-based reinforcement learning model that orchestrates the device grouping strategy to optimize device placement. Thus, the model guarantees a higher probability of success for the devices during data transmission access, eventually leading to more efficient energy consumption. Through thorough quantitative simulations, we demonstrate that the proposed learning-based approach significantly outperforms the other baseline grouping methods.
Introduction of the Approach for Reviving the Sub-Municipal Level as a Spatial Aspect of Decentralization in Serbia
Authors: Drobnjaković Marija , Panić Milena
Published: May 2024

Decentralization is a globally accepted concept of separation, the diversity of structures within the political system, the transfer of resources, activities, and powers in the decision-making process, and the division of tasks from the central government to lower authorities. It is implemented in both developed and developing countries, with different aims and consequences. In Serbia, the urban-centric development model and centralized governance caused rural settlements to become non-viable, and services and opportunities were deprived. This research has been undertaken in order to provide a deeper understanding of the territorial aspect of decentralization in Serbia and how it affects rural areas. It strives to offer a methodological framework for the identification of central settlements in rural areas of Serbia that will serve as a focal point for settlements networking in order to facilitate the spatial integration of rural areas and governance at the local level. This research encompasses (i) the identification of rural nodes as bearers of balanced governance and spatial development; (ii) the delimitation of their gravity sphere; and (iii) the determination of the relationship between settlement organization models and decentralization in Serbia. The research results indicate that identified rural nodes can be valuable to developing a holistic understanding of rural issues, supporting a bottom-up approach and regional disparities mitigation.
A Dual-Layer Complex Network-Based Quantitative Flood Vulnerability Assessment Method of Transportation Systems
Authors: Ding Jiayu , Wang Yuewei , Li Chaoyue
Published: May 2024

Evaluating the vulnerability of urban transportation systems to flood disasters can provide scientific support for urban disaster prevention and mitigation. Current methods for assessing the flood vulnerability of urban roads often overlook the internal relationships within the complex spatial composition of road networks and surface structures. In this study, based on the theory of complex networks, a dual-layer network assessment model is established for evaluating the flood vulnerability of urban transportation systems by coupling basic geographic data with road network vector data. Unlike traditional methods, this model considers the complex relationship between road network structures and ground surfaces, uncovering a correlation between road network structure and road flood vulnerability. By utilizing this model, the flood vulnerability of road networks in Shenzhen, as well as the city’s spatial flood vulnerability, are quantitatively assessed. Based on the quantitative results, we create maps illustrating the distribution of road and spatial flood vulnerability in Shenzhen. The study results reflect that roads highly vulnerable to flooding are mainly located in the central urban area of the southwest, with the flood vulnerability spatially concentrated primarily in the northern and western regions. Using data from government reports, news stories, and other sources over the past five years, we compile recorded instances of urban waterlogging. The quantitative results of the model are consistent with the distribution trend in recorded waterlogging points, indicating that the model’s outcomes are authentic and reliable.
Practicing Multilevel Governance: The Revision of the Piedmont Regional Territorial Plan
Authors: Todella Elena , Abastante Francesca , Cotella Giancarlo
Published: May 2024

The regional level plays a relevant role in spatial governance and planning in Europe, as it constitutes the most suitable scale to both program European Union funding and territorialize international development strategies. In this light, regional spatial planning instruments play a crucial role in translating general objectives and recommendations (e.g., those included in the UN 2030 Agenda for Sustainable Development) in place-based implementation practices. This contribution reflects upon the implementation of a methodology aimed at engaging a multidisciplinary team of students in the revision of the Piedmont regional territorial plan (PTR), developed in close cooperation with the regional public administration. This problem-based learning activity supported the integration of supranational strategic objectives and funding streams with the regional territorial development priorities. In so doing, it represents a possible way to practice multilevel governance in concrete terms, employing the PTR as a meaningful catalyst.
Quantifying Urban Spatial Morphology Indicators on the Green Areas Cooling Effect: The Case of Changsha, China, a Subtropical City
Authors: Li Jiang , Wang Hao , Cai Xiaoxi , Liu Shaobo , Lai Wenbo , Chang Yating , Qi Jialing , Zhu Gexuan , Zhang Chuyu , Liu Yudan
Published: May 2024

Green city areas are crucial in mitigating the Urban Heat Island Effect (UHI). However, the cooling effect of green city areas can be influenced by the surrounding complex urban spatial environment. This study focuses on Changsha, a subtropical city in China, where 40 green city areas were screened and analyzed. The study aims to quantify the specific impact of urban spatial morphology on the cooling effect of green city areas. Through statistical correlation and regression analysis, this study focused on six urban spatial morphology indicators: building density (BD), building floor area ratio (BFR), building volume density (BVD), building evenness index (BEI), building average height (BH), and building height standard deviation (BSD). The results indicate that the cooling effect of green city areas could be influenced by urban spatial morphology. Factors such as BD, BFR, BH, and BSD were found to be significantly correlated with the cooling effect of green city areas, with BH showing the strongest influence. BD and BFR were negatively correlated, while BH and BSD were positively correlated. The range values of BD, BFR, BH, and BSD were determined to achieve the optimal conditions for the cooling effect of green city areas. Additionally, the relative position of the green city areas in the neighboring urban areas affects the cooling effect of the green city areas. The cooling effect is most pronounced in the urban area situated to the south of the green city areas. These findings provide a solid foundation for urban planning around green city spaces and offer scientifically sound evidence for mitigating the UHI.
Digital and Culture: Towards More Resilient Urban Community Governance
Authors: Xiang Hongxun , Heng Xia , Zhai Boleng , Yang Lichen
Published: May 2024

Urban communities are characterized by significant population size, high density, and strong mobility. While we might enjoy the dividends of rapid modernization, there are nonetheless variable and frequent public crises that occur. Modernization’s problems are gradually emerging, and the traditional risk prevention logic that relies on administrative “rigidity” has begun to be widely challenged. Traditional urban communities depend on institutional, structural, and spatial aspects to improve community resilience. Because big data has become popular, attention has begun to be paid to digital empowerment and community resilience. However, the emergence of problems such as “digital paradox” and “digital ethics” in the digital realm itself has prompted calls for cultural resilience to continue to rise. Therefore, urgently needed resolutions are required to questions regarding the resilience of traditional communities, the construction of digital and cultural resilience, the relationship between digital and cultural resilience, and the manner in which cultural resilience is coordinated to solve the problem of digital resilience. A quantitative analysis of 350 questionnaires from five urban communities found that these communities’ institutional, spatial, and structural dimensions are the driving factors for improving resilience. In contrast, the cultural and digital dimensions are constraints. Therefore, the question of how to coordinate the cultural and digital factors represented by traditional and modern societies in order to compensate for the shortcomings in resilience construction is that which future urban communities must consider. The authors of this study believe that digital empowerment is needed to open up the “first mile” of resilient communities, that cultural empowerment is required to break down the “blocks in the middle” of resilient communities, and that digital and cultural coupling is needed to link the “last mile” of resilient communities. One must use culture to compensate for the shortcomings of digital resilience and digital to pay for the failures of cultural resilience before one can move towards more resilient urban community governance.
Korean Paradox of Public Support for the Research and Development Investment in the Sustainable Performance of the Regional Economy
Authors: Choi Yongrok , Li Siyu , Lee Hyoungsuk
Published: May 2024

The Swedish Paradox is a well-known phenomenon related to high research and development (R&D) investment with supposedly low aggregate economic performance owing to economic saturation. The Korean economy has not yet become an advanced economy; however, its R&D performance is negligible. Recently, also the R&D share of the GNP has become much higher, and its contribution to the economic growth rate is rapidly decreasing, implying a negative relationship between R&D activities and economic performance. This study uses slacks-based data envelopment analysis to investigate investment performance at the local government level in Korea. Our findings reveal that the average score for R&D investment performance in Korea is 64%, indicating huge potential for an efficiency enhancement of 36%. Notably, among the 16 local governments examined, Seoul and its surrounding metropolitan areas showed the lowest R&D efficiency, while Gangwon and Gwangju exhibited superior performance. Since these two regions have promoted specific missions, such as the medical hub in Gangwon and the optical fiber strategic platform in Gwangju, precise and accurate differentiation appears necessary to avoid a lack of governance. To determine the workable mechanism of R&D support policies, we further divided R&D productivity into three categories by incorporating the Malmquist Index (MI). The paper productivity of R&D shows an increasing trend over the experimental period from 2016 to 2021. However, overall, the MI shows slightly deteriorating productivity with 0.978, owing to the aggravating effect of patents and commercialization of R&D. The success in the paper comes from the harmonized partnership between the strong push factor of the government and voluntary pull factor of the R&D support receiving universities. Thus, we suggest that the Korean government should not depend on the superficial effectiveness of R&D in the term but on public–private partnerships with stronger performance-oriented responsibility.
Microbiome Modulation in Acne Patients and Clinical Correlations
Authors: Ionescu Marius-Anton , Tatu Alin Laurentiu , Busila Camelia , Axente Elena Roxana , Badalato Nelly , Feuilloley Marc G. J. , Asquier Estelle , Martínez José Dario , Lefeuvre Luc
Published: May 2024

Background: The imbalance of skin microbiota in acne can induce changes leading to induction or to aggravation of chronic inflammatory lesions; complex mechanisms are involved. Cutibacterium acnes (C. acnes) ribotypes RT4 and RT5 express more biofilm and are associated with inflammatory acne lesions. C. acnes RT6 is a non-acne ribotype, beneficial for the skin. Objectives: In an open clinical trial, acne adults were included and assessed clinically at baseline and at month 2 using the Investigator Global Assessment of Acne (IGA) score. A topical emulsion was applied twice daily for 2 months (M2) in each included patient. In the same series of acne patients, skin swab samples were collected from acne patients at baseline and M2 from lesional and non-lesional skin; skin swabs were collected for the metagenomic long-read analysis of microbiota. Materials and Methods: Acne patients with a gravity score IGA of >1<3 were included in this pilot study. An emulsion of O/W formulated with vegetal extract of Umbelliferae associated with a polysaccharide at 1% was applied twice daily for 2 months. At baseline and M2 clinical assessments were made; skin swab samples were also taken for microbiota analysis from lesional and non-lesional skin in each included patient. Extractions of genomic DNA (gDNA) from swab samples from baseline and from M2 were made, followed by full-length (V1–V9) amplification of the 16S rDNA and sequencing of amplicon libraries for strain-level bacterial community profiling. Results: In a series of 32 adult acne patients, the mean initial IGA scale was 3.1; at M2 the IGA scale was 1.5 (p < 0.001). The mean decrease in acne lesions was by 63%. Microbiome metagenomic long-read analysis in these series was mainly dominated by C. acnes followed by Staphylococcus epidermidis (S. epidermidis). The density of C. acnes ribotypes RT6 (non-acne strain) was increased at M2 compared to baseline and the density of ribotypes C. acnes RT1 to RT5 was decreased at M2, compared to baseline (p < 0.0001). S. epidermidis ribotypes (1 to 36) were non significantly increased at M2, compared to baseline (p < 0.1). Conclusions: In a series of 32 acne patients that applied an emulsion based on vegetal extract of Umbelliferae and a polysaccharide at 1% twice daily, a significant clinical improvement in IGA scale for acne lesions was seen at M2, compared to baseline (p < 0.0001). The clinical improvement was correlated with an improvement in skin microbiome at M2 compared to baseline, indicated by the increase in the relative abundance of non-acne strain of C. acnes ribotype 6 and of the decrease in the relative abundance of acne strains ribotypes C. acnes RT1 to RT5.
Afamelanotide for Treatment of the Protoporphyrias: Impact on Quality of Life and Laboratory Parameters in a US Cohort
Authors: Leaf Rebecca K. , Naik Hetanshi , Jiang Paul Y. , Elmariah Sarina B. , Hodges Pamela , Mead Jennifer , Trinidad John , Saberi Behnam , Tran Benny , Valiante Sarah , Mernick Francesca , Leaf David E. , Anderson Karl E. , Dickey Amy K.
Published: May 2024

Background: Erythropoietic protoporphyria (EPP) and X-linked protoporphyria (XLP) are rare disorders of heme biosynthesis characterized by severe cutaneous phototoxicity. Afamelanotide, an α-melanocyte-stimulating hormone analogue, is the only approved treatment for protoporphyria and leads to increased light tolerance and improved quality of life (QoL). However, published experience with afamelanotide in the US is limited. Methods: Here, we report on all adults who received at least one dose of afamelanotide at the Massachusetts General Hospital Porphyria Center from 2021 to 2022. Changes in the time to phototoxic symptom onset, QoL, and laboratory parameters were assessed before and during treatment with afamelanotide. Results: A total of 29 patients with protoporphyria were included, 26 of whom (72.2%) received ≥2 afamelanotide implants. Among the patients who received ≥2 implants, the median time to symptom onset following sunlight exposure was 12.5 min (IQR, 5–20) prior to the initiation of afamelanotide and 120 min (IQR, 60–240) after treatment (p < 0.001). Improvements in QoL during afamelanotide treatment were measured using two QoL tools, with good correlation observed between these two instruments. Finally, we found no improvements in the median levels of metal-free erythrocyte protoporphyrin, plasma protoporphyrin, or liver biochemistries during versus prior to the initiation of afamelanotide treatment. Conclusions: This study highlights a dramatic clinical benefit of afamelanotide in relation to light tolerance and QoL in protoporphyria, albeit without improvement in protoporphyrin levels or measures of liver function.
An Editorial on the Special Issue “Genetic Basis of Human Diseases”
Authors: Churnosov Mikhail
Published: May 2024

The role of heredity in the emergence of the overwhelming majority of human diseases is currently considered proven and has significant importance [...]
In Vitro Evaluation of Synergistic Essential Oils Combination for Enhanced Antifungal Activity against Candida spp.
Authors: Hleba Lukáš , Hlebová Miroslava , Charousová Ivana
Published: May 2024

In recent years, a significant number of infections have been attributed to non-albicidal Candida species (NAC), mainly due to the increasing resistance of NAC to antifungal agents. As only a few antifungal agents are available (azoles, echinocandins, polyenes, allylamines and nucleoside analogues), it is very important to look for possible alternatives to inhibit resistant fungi. One possibility could be essential oils (EOs), which have been shown to have significant antifungal and antibacterial activity. Therefore, in this study, the efficacy of 12 EOs and their combinations was evaluated against four yeasts of the genus Candida (C. albicas, C. glabrata, C. tropicalis and C. parapsilosis). GC-MS and GC-MS FID techniques were used for the chemical analysis of all EOs. VITEK-2XL was used to determine the antifungal susceptibility of the tested Candida spp. strains. The agar disc diffusion method was used for primary screening of the efficacy of the tested EOs. The broth dilution method was used to determine the minimum inhibitory concentrations (MICs) of the most potent EOs. After MIC cultivation, the minimum fungicidal concentration (MFC) was determined on Petri dishes (60 mm). The synergistic effect of combined EOs was evaluated using the checkerboard method and expressed as a fractional inhibitory concentration index (FICI). The results showed that ginger > ho-sho > absinth > dill > fennel > star anise > and cardamom were the most effective EOs. For all Candida species tested, the synergy was mainly observed in these combinations: ginger/fennel for C. albicans FICI 0.25 and C. glabrata, C. tropicalis and C. parapsilosis FICI 0.5 and absinth/fennel for C. albicans FICI 0.3125, C. tropicalis FICI 0.3125 and C. parapsilosis FICI 0.375. Our results suggest that the resistance of fungal pathogens to available antifungals could be reduced by combining appropriate EOs.
Nutritional and Psychosocial Impact of Food Allergy in Pediatric Age
Authors: Pecoraro Luca , Mastrorilli Carla , Arasi Stefania , Barni Simona , Caimmi Davide , Chiera Fernanda , Dinardo Giulio , Gracci Serena , Miraglia Del Giudice Michele , Bernardini Roberto , Giannetti Arianna
Published: May 2024

Treatment of IgE-mediated food allergy involves avoiding the food causing the allergic reaction. In association, an action plan for allergic reactions is indicated, sometimes including self-injectable adrenaline. In addition to these dietary and medical implications, there are two equally important ones: nutritional and psychosocial. From a nutritional point of view, it is known that children suffering from food allergy have a growth delay in height and weight compared to their non-allergic peers. Specifically, this condition is directly related to the specific food excluded from the diet, the number of foods excluded and the duration of the elimination diet. From a psychosocial point of view, the child often cannot eat the foods other guests eat. Children with food allergy may perceive an aura of parental anxiety around their mealtime and may be afraid that what they eat could have harmful consequences for their health. Furthermore, children’s and their parents’ quality of life appears to be affected. The need to manage the allergy and the nutritional and psychosocial problems positions the pediatric nutritionist and the child neuropsychiatrist as support figures for the pediatric allergist in managing the child with food allergy.
Improved Tribological Performance of a Polybutylene Terephthalate Hybrid Composite by Adding a Siloxane-Based Internal Lubricant
Authors: Zhao Shengqin , Merz Rolf , Emrich Stefan , L’huillier Johannes , Lin Leyu
Published: May 2024

To mitigate the environmental hazards aroused by fossil-based lubricants, the development of eco-friendly internal lubricants is imperative. Siloxane-based internal lubricants, widely applied as plasticizers in polymeric compounds, are a promising option. However, their impacts on the tribological properties of polymeric tribocomponents are still unclarified. Therefore, in the current study, a siloxane-based internal lubricant with the product name ‘EverGlide MB 1550 (EG)’ was dispersed into a polybutylene terephthalate (PBT)-based tribological composite to investigate whether the tribological properties of the composite can be optimized. A block-on-ring (BOR) test configuration was used for this purpose. It was found that the addition of EG to the composite significantly improved the tribological behavior; the improvement was particularly significant under lower load conditions (pv-product ≤ 2 MPa∙m/s). Compared to the reference PBT composite, the addition of EG reduced the friction coefficient (COF) by about 30% and the specific wear rate by about 14%. An accompanying surface analytical investigation using photoelectron spectroscopy to elucidate the effective mechanisms at the molecular level showed the availability of tribologically effective and free EG after its addition to the composite in the relevant tribocontact.
Comparative Study on Passive Film Formation Mechanism of Cast and PBF-LB/M-TC4 in Simulated Physiological Solution
Authors: Liu Ming , Liu Zhang , Wang Jie , Zhang Yongqiang , Gao Xin
Published: May 2024

Personalized laser powder bed fusion (PBF-LB/M) Ti-6Al-4V (TC4) has a broader application prospect than that of traditional casting. In this paper, the composition and corrosion resistance of the passive film formation mechanism of TC4 prepared by optimization of PBF-LB/M techniques and traditional casting were systematically studied in 0.9 wt.% NaCl at 37 °C by electrochemical technique and surface analysis. The rates of the passive film formation process, corrosion resistance and composition of TC4 show different characteristics for the different preparation processes. Although the rate of passive film formation of cast-TC4 was higher at the initial immersion, the open circuit potential was more positive, and the film thickness was larger after stabilization, those facts show no positive correlation with corrosion resistance. On the contrary, with no obvious defects on the optimized PBF-LB/M-TC4, the passive film resistance is 2.5 times more, the defect concentration is reduced by 30%, and the TiO2 content is higher than that of the cast-TC4, making the martensitic-based PBF-LB/M-TC4 exhibit excellent corrosion resistance. This also provides good technical support for the further clinical application of PBF-LB/M-TC4.
Characterizing Macroporous Ion Exchange Membrane Adsorbers for Natural Organic Matter (NOM) Removal—Adsorption and Regeneration Behavior
Authors: Wullenweber Jon , Bennert Julia , Mantel Tomi , Ernst Mathias
Published: May 2024

Addressing the characterization of Natural Organic Matter (NOM) removal by functionalized membranes in water treatment, this study evaluates the effectiveness of two commercial ion-exchange membrane adsorbers: Sartobind® Q (with quaternary amines) and D (with tertiary amines). Using Suwannee River NOM (SRNOM) as a surrogate, Langmuir adsorption isotherms revealed maximum capacities (Qmax) of 2966 ± 153 mg C/m2 and 2888 ± 112 mg C/m2, respectively. Variations in flux from 50 to 500 LMH had a minimal impact on breakthrough times, proving low diffusion limitations. The macroporous (3–5 µm) functionalized cellulose-based membranes exhibited high permeabilities of 10,800 L/(h m2 bar). Q maintained positive zeta potential vs. pH, while D’s zeta potential decreased above pH 7 due to amine deprotonation and turning negative above an isoelectric point of 9.1. Regeneration with 0.01 M NaOH achieved over 95% DOC regeneration for Sartobind® D, characterizing reversibility through a pH-swing. Cyclic adsorption showed that Q maintained its capacity with over 99% DOC regeneration, while D required acidic conditioning after the first regeneration cycle to mitigate capacity reduction and re-deprotonate the adsorber. These results have demonstrated the potential suitability of adsorber membranes, designed originally for biotechnological purposes, for the possible removal of disinfection byproduct precursors in drinking water treatment.
Failure Mechanism of Rear Drive Shaft in a Modified Pickup Truck
Authors: Huang Zhichao , Wang Jiaxuan , Hu Yihua , Jiang Yuqiang , Xu Yong , Wan Xiongfei
Published: May 2024

This paper investigates the failure mechanism of the rear drive shaft in a modified pickup truck which had operated for about 3000 km. The investigation included macroscopic and microscopic evaluation to document the morphologies of the fracture surface, measurement of the material composition, metallographic preparation and examination, mechanical testing, and finite element modelling and calculations. The results obtained suggest that rotation-bending fatigue was the primary cause of the drive shaft failure. The crack initiation is located in the root of the machined threads on the drive shaft surface and expanded along the side of the machining line surface. The main cause of fatigue cracks is attributable to a high stress concentration owing to a large unilateral bending impact under overload. Meanwhile, the bidirectional torsional force also produces a higher stress concentration and thus accelerates the fatigue crack to expand radially along the surface. Furthermore, the hardness of the central section of the drive shaft was marginally below standard. This deficiency results in harm to the bearings and other mechanical components, as well as expediting the enlargement of cracks. Finite element analysis revealed significant contact stress between the bearing and drive shaft, with stress levels exceeding the fatigue limit stress of the parent material. This highlights the need for reevaluation of the heat treatment process and vehicle loading quality to enhance the drive shaft’s longevity.
Texture Evolution and Plastic Deformation Mechanism of Cold-Drawn Co-Cr-Ni-Mo Alloy
Authors: Liu Hanyuan , Hu Rui , Xia Xupeng , Yu Sen
Published: May 2024

The plastic deformation behavior and mechanisms of Co-Cr-Ni-Mo alloy were investigated. The wires were subjected to different reductions using a multi-pass drawing approach and the resulting microstructures were characterized by EBSD and TEM. It was found that the alloy cold-drawn from surface to center exhibited non-uniform radial strain, with decreasing strain from surface to center. As the strain increased, the transverse texture of the alloy evolved from the initial bimodal texture consisting of strong {100}<110> and weak {110}<001> components to bimodal texture with {110}<233> and {112}<111> components, with significant twinning and mirror orientation between twin and matrix. The longitudinal texture evolution of the alloy mainly occurred on the α-fiber line, and ultimately did not form a significant texture due to grain elongation and crystal rotation. The plastic deformation mechanism of the Co-Cr-Ni-Mo alloy was dominated by dislocation slip at lower strain levels, which gradually transitioned to a combination of dislocation slip and twinning at higher strain levels. The deformation twins were typically distributed in high-density dislocation regions, and the twin boundaries transformed into high-angle sub-grain boundaries, hindering the extension of dislocation slip and deformation twin. With the increase in strain, work hardening results in a significant increase in strength and microhardness.
Investigation of Synthesis, Characterization, and Finishing Applications of Spherical Al2O3 Magnetic Abrasives via Plasma Molten Metal Powder and Powder Jetting
Authors: Wang Shujun , Zhang Yusheng , Meng Shuo , Zhao Yugang , Meng Jianbing
Published: May 2024

Magnetic abrasive finishing (MAF) is an efficient finishing process method using magnetic abrasive particles (MAPs) as finishing tools. In this study, two iron-based alumina magnetic abrasives with different particle size ranges were synthesized by the plasma molten metal powder and powder jetting method. Characterization of the magnetic abrasives in terms of microscopic morphology, phase composition, magnetic permeability, particle size distribution, and abrasive ability shows that the magnetic abrasives are spherical in shape, that the hard abrasives are combined in the surface layer of the iron matrix and remain sharp, and that the hard abrasives combined in the surface layer of the magnetic abrasives with smaller particle sizes are sparser than those of the magnetic abrasives with larger particle sizes. The magnetic abrasives are composed of α-Fe and Al2O3; the magnetic permeability of the magnetic abrasives having smaller particle sizes is slightly higher than that of the magnetic abrasives having larger particle sizes; the two magnetic abrasives are distributed in a range of different particle sizes; the magnetic abrasives have different magnetic permeabilities, which are higher than those of the larger ones; both magnetic abrasives are distributed in the range of smaller particle sizes; and AZ31B alloy can obtain smaller surface roughness of the workpiece after the grinding process of the magnetic abrasives with a small particle size.
Single-Step Fabrication of Highly Tunable Blazed Gratings Using Triangular-Shaped Femtosecond Laser Pulses
Authors: Fantova Jorge , Rodríguez Ainara , Omeñaca Luis , Beldarrain Oihane , Mandayo Gemma G. , Olaizola Santiago M. , Lens José , Gomez-Aranzadi Mikel
Published: May 2024

Blazed gratings are periodic surface structures of great interest for applications such as friction control, light trapping, and spectrometry. While different laser processing methods have been explored to produce these elements, they have not yet surpassed conventional surface manufacturing techniques, often based on lithography processes or mechanical ruling. This work introduces a new approach based on the combination of ultrashort pulses and triangular beam shaping, which enables the generation of asymmetrical grooves in a single step. The main advantage of this strategy is that by simply changing the laser processing direction we can induce a significant modification in the ratio of asymmetry between the sidewall angles of the machined channels. The paper includes a comprehensive study, which has been supported by statistical tools, of the effect of this and other experimental parameters on the morphology of grooves machined on stainless steel. As a result, we achieved a wide range of geometries, with asymmetry ratios spanning from 1 to 5 and channel depths between 3 and 15 µm. Furthermore, we demonstrate the validity of the approach through the successful manufacture of blazed gratings of various slopes. The results reflect the versatility and cost-efficiency of the proposed fabrication strategy, and thus its potential to streamline the production of sawtooth gratings and other devices that are based on asymmetrical features.
Experimental and Numerical Study of a Trapezoidal Rib and Fan Groove Microchannel Heat Sink
Authors: Jin Lufan , Wang Junchao , Cai Yixun , Yang Guangzhao , Hua Xuebing , Zhong Zhenggeng , Pan Xiao , Cai Chengyu , Qin Jia , Cao Mingxuan
Published: May 2024

A novel microchannel heat sink (TFMCHS) with trapezoidal ribs and fan grooves was proposed, and the microchannel was manufactured using selective laser melting technology. Firstly, the temperature and pressure drop at different power levels were measured through experiments and then combined with numerical simulation to explore the complex flow characteristics within TFMCHSs and evaluate the comprehensive performance of microchannel heat sinks based on the thermal enhancement coefficient. The results show that, compared with rectangular microchannel heat sinks (RMCHSs), the average and maximum temperatures of TFMCHSs are significantly reduced, and the temperature distribution is more uniform. This is mainly caused by the periodic interruption and redevelopment of the velocity boundary layer and thermal boundary layer caused by ribs and grooves. And as the heating power increases, the TFMCHS has better heat dissipation performance. When P=33 W and the inlet flow rate is 32.5 mL/min, the thermal enhancement factor reaches 1.26.
Influence of Mineralogy and Mineralogy Approach to Optimize Processing: A Case Study of Tin–Copper Polymetallic Ore
Authors: Ye Xiaolu , Tong Xiong , Xie Xian
Published: May 2024

Tin-Copper polymetallic ore is a type of typical ore that cassiterite is closely associated with sulfide minerals. In mineral processing of tin–copper polymetallic ore, flotation is generally used to recover valuable sulfide minerals, while gravity separation is used to recover cassiterite. A mine in Yunnan, China, uses the traditional “flotation–gravity separation” process to recover copper and tin but faces several problems during processing, such as an insufficient copper grade in Cu concentrate, a much higher grade of As in S concentrate, and a grade of S in Sn concentrate that exceeds the standard. A process mineralogy study was conducted, with a focus on Cu–S mixed concentrate, S concentrate, and Sn rough concentrate. It was determined that the main cause of these problems is not the liberation or size distribution of valuable minerals but the superstructure of pyrrhotite, which represents one of the most abundant minerals in the products. Based on EMPA, SEM-EDS, and XRD data, both monoclinic pyrrhotite and hexagonal pyrrhotite occurred in all samples. The abundance of different superstructures of pyrrhotite in one sample was determined by means of particle extraction and area calculation from microscopic images, and the distribution characteristics of monoclinic pyrrhotite and hexagonal pyrrhotite in the whole process were clarified. This process mineralogy study indicates that the strong magnetic hexagonal pyrrhotite mainly affects the copper recovery during flotation, and the hexagonal pyrrhotite mainly affects the recovery of cassiterite during gravity separation. Strong magnetic monoclinic pyrrhotite and weak magnetic hexagonal pyrrhotite should be fully considered in the optimization of mineral processing, and the magnetic separation of pyrrhotite should be adopted to optimize the overall environment of copper flotation and tin gravity separation.
Use of Metallic Mercury in Artisanal Gold Mining by Amalgamation: A Review of Temporal and Spatial Trends and Environmental Pollution
Authors: Donkor Augustine K. , Ghoveisi Hossein , Bonzongo Jean-Claude J.
Published: May 2024

The introduction of mercury (Hg) into the environment by anthropogenic activities has resulted in negative implications for ecosystem functions and human health. Unlike the legacy of huge environmental pollution left by historic gold rushes in several developed countries, gold-rich nations in the developing world are currently witnessing what could qualify as a “new gold rush”, conducted primarily by small-scale mining operators and characterized by the use of metallic Hg (Hg0) in the amalgamation process to extract gold from crude ores. Once introduced into the environment, Hg0 can undergo biogeochemical transformations to produce Hg species such as methyl-Hg, with well-established adverse impacts on living organisms. This review summarizes published data on both historical and recent trends of the use of Hg0 in artisanal gold mining (AGM) on a global scale and emphasizes the impacts of AGM on the environment. To achieve this, we used citations from research conducted in North and South America, Europe, Asia, Africa, Australia, and New Zealand, obtained from several search engines and databases. Our findings show that, in addition to the well-known environmental and human health adverse effects of gold mining with Hg0, gold extraction by the Hg amalgamation technique is boosting the economy in parts of Africa, South America, and Asia. Unfortunately, this appealing aspect of AGM may not be easily halted, pending the creation of alternative employment. Therefore, there is a clear need for the development of safe and affordable gold extraction and purification technologies. Ultimately, the growth of this specific economic sector should be regulated to help protect both the environment and human health. Information compiled in this review should help to (i) improve the mapping of AGM-impacted soil and aquatic systems on a global scale and (ii) stimulate discussions and research on how to take down current barriers to the development and implementation of safe AGM methods.
Historical Pigments and Paint Layers: Raman Spectral Library with 852 nm Excitation Laser
Authors: Innocenti Silvia , Quintero Balbas Diego , Galeotti Monica , Cagnini Andrea , Porcinai Simone , Striova Jana
Published: May 2024

Raman spectroscopy (RS), for its robust analytical capabilities under constant development, is a powerful method for the identification of various materials, in particular pigments in cultural heritage. Characterization of the artist’s palette is of fundamental importance for the correct formulation of restoration intervention as well as for preventive conservation of artworks. Here we examine the number and variability of research studies exploiting Bravo handheld Raman spectrophotometer relying on the excitation of Raman signal with temperature-shifted diode lasers emitting at 852 and 785 nm. To this end, we explore the spectral features of common historical pigments examined as powders and in the paint layer. We show that some materials may exhibit slightly different spectra as concerns especially the relative intensity of Raman lines with 852 nm laser excitation wavelength as compared to the standard 785 nm. The aim is to provide the research community with a reference spectral database that facilitates the identification of unknown pigments using the 852 nm excitation source.
Three-Dimensional Electrical Structure and Metallogenic Background of the Southeastern Hubei Ore Concentration Area
Authors: Xu Daili , Zhang Yiwu , Tang Baoshan , Yan Guolong , Ye Gaofeng , Dong Ji’en , Liu Bo , Zhang Yiming
Published: May 2024

The Southeastern Hubei Ore Concentration Area (SHOCA) is located in the west section of the Middle and Lower Yangtze River Metallogenic Belt in China, and it is a significant copper and iron mining region in China. Here, 117 pieces of magnetotelluric array data were used to obtain a three-dimensional resistivity model of the SHOCA and to investigate the relationship between the deep electrical features and the genesis of mineral deposits. The model shows that the Qinling-Dabie Orogenic Belt exhibits high-resistivity characteristics, representing Mesozoic granites and high-pressure to ultra-high-pressure metamorphic rocks. There are several low-resistivity anomalies in the upper crust of the SHOCA, which are connected to the widespread low-resistivity anomaly in the middle-lower crust. Near the Yangxin-Changzhou Fault, there is evidence of an electrical gradient zone. The Xiangfan-Guangji Fault, located at the south margin of the Qinling-Dabie Orogenic Belt, also exhibits distinct high- and low-resistivity boundaries at the upper crust. However, the Yangtze Fault and the Tancheng-Lujiang Fault manifest as resistivity gradient zones at the lithospheric scale. These faults are connected the low-resistivity anomaly in the middle to lower crust, possibly serving as upwelling channels of deep thermal fluids, exerting control over shallow diagenesis and mineralization processes. The low-resistivity anomaly in the middle to lower crust of the SHOCA is explained as partial melting resulting from the mixing of crustal and mantle materials. These low-resistivity anomalies play a role as source components in the mineralization system, where mineral-rich hydrothermal fluids migrate upward along intra-basin faults, exerting control over the distribution of shallow mineral deposits.
Polyaromatic Hydrocarbon Inclusion Complexes with 2-Hydroxylpropyl-β/γ-Cyclodextrin: Molecular Dynamic Simulation and Spectroscopic Studies
Authors: Alsadun Norah S. , Alfadil Amira A. , Elbashir Abdalla A. , Suliman FakhrEldin O. , Ali Omar Mei Musa , Ahmed Amel Y.
Published: May 2024

In aqueous and solid media, 2-HP-β/γ-CD inclusion complexes with poly aromatic hydrocarbon (PAH) Phenanthrene (PHN), Anthracene (ANT), Benz(a)pyrene (BaP), and Fluoranthene (FLT) were investigated for the first time. The inclusion complexes were characterized and investigated using fluorescence and 1HNMR spectroscopy. The most prevalent complexes consisting of both guests and hosts were those with a 1:1 guest-to-host ratio. The stability constants for the complexes of PHN with 2-HP-β-CD and 2-HP-γ-CD were 85 ± 12 M−1 and 49 ± 29 M−1, respectively. Moreover, the stability constants were found to be 502 ± 46 M−1 and 289 ± 44 M−1 for the complexes of ANT with both hosts. The stability constants for the complexes of BaP with 2-HP-β-CD and 2-HP-γ-CD were (1.5 ± 0.02) × 103 M−1 and (9.41 ± 0.03) × 103 M−1, respectively. The stability constant for the complexes of FLT with 2-HP-β-CD was (1.06 ± 0.06) × 103 M−1. However, FLT was observed to form a weak complex with 2-HP-γ-CD. Molecular dynamic (MD) simulations were used to investigate the mechanism and mode of inclusion processes, and to monitor the atomic-level stability of these complexes. The analysis of MD trajectories demonstrated that all guests formed stable inclusion complexes with both hosts throughout the duration of the simulation time, confirming the experimental findings. However, the flexible Hydroxypropyl arms prevented the PAHs from being encapsulated within the cavity; however, a stable exclusion complex was observed. The main forces that influenced the complexation included van der Waals interactions, hydrophobic forces, and C–H⋯π interaction, which contribute to the stability of these complexes.
Fluorescent Materials Based on Spiropyran for Advanced Anti-Counterfeiting and Information Encryption
Authors: Ding Sha , Lv Xin , Xia Yong , Liu Yuejun
Published: May 2024

In daily life, counterfeit and substandard products, particularly currency, medicine, food, and confidential documents, are capable of bringing about very serious consequences. The development of anti-counterfeiting and authentication technologies with multilevel securities is a powerful means to overcome this challenge. Among various anti-counterfeiting technologies, fluorescent anti-counterfeiting technology is well-known and commonly used to fight counterfeiters due to its wide material source, low cost, simple usage, good concealment, and simple response mechanism. Spiropyran is favored by scientists in the fields of anti-counterfeiting and information encryption due to its reversible photochromic property. Here, we summarize the current available spiropyran-based fluorescent materials from design to anti-counterfeiting applications. This review will be help scientists to design and develop fluorescent anti-counterfeiting materials with high security, high performance, quick response, and high anti-counterfeiting level.