bluuebunny/crossref_metadata_2025 huggingface dataset:
Measuring the Evolution of Urban Resilience Based on the Exposure–Connectedness–Potential (ECP) Approach: A Case Study of Shenyang City, China
Authors: Feng Xinghua , Xiu Chunliang , Li Jianxin , Zhong Yexi
Published: December 2021

Resilience is a new path to express and enhance urban sustainability. Cities suffer from natural shocks and human-made disturbances due to rapid urbanization and global climate change. The construction of an urban resilient developmental environment is restricted by these factors. Strengthening the comprehensive evaluation of resilience is conducive to identifying high-risk areas in cities, guiding regional risk prevention, and providing a scientific basis for differentiated strategies for urban resilience governance. For this study, taking Shenyang city as a case study, the resilience index system was constructed as an ECP (“exposure”, “connectedness”, and “potential”) framework, and the adaptive cycle model was introduced into the resilience assessment framework. This model not only comprehensively considers the relationship between exposure and potential but also helps to focus on the temporal and spatial dynamics of urban resilience. The results show that the exposed indicators have experienced three spatial evolution stages, including single-center circle expansion, multicenter clustering, and multicenter expansion. The potential index increased radially from the downtown area to the outer suburbs, and the low-value area presented a multicenter pattern. The spatial agglomeration of connectivity indicators gradually weakened. The results reflect the fact that the resilience level of the downtown area has been improved and the resilience of the outer expansion area has declined due to urban construction. The multicenter cluster pattern is conducive to the balance of resilience levels. In terms of the adaptive cycle phases of urban resilience, the first ring has gone through three phases: exploitation (r), conservation (K), and release (Ω). The second and third rings have gradually shifted from the exploitation (r) phase to the conservation (K) phase. The fourth ring has entered the exploitation (r) phase from the reorganization (ɑ) phase. The fifth ring and its surrounding areas are in the reorganization (ɑ) phase. The results provide specific spatial guidance for implementing resilient urban planning and realizing sustainable urban development.
Add, Transform, and Utilize. Possibilities of Applying Druot, Lacaton, and Vassal’s Modernization Strategies and Solutions in Polish Large-Panel Housing Estates
Authors: Trzcińska Milena
Published: December 2021

In 2004, in response to France’s 1960s and 1970s urban regeneration program proposing the demolition and redevelopment of large scale social housing developments, Frédérik Druot, Anne Lacaton, and Jean-Philippe Vassal created their PLUS theory (PLUS—Les grands ensembles de logements–Territoires d’exception). Its main aim was to modernize the existing buildings, and to add extra living space, functional freedom, and comfort. This essay examines the PLUS strategy and two of the architects’ projects: the Bois le Prêtre Tower in Paris and the Grand Parc housing estate in Bordeaux. Its aim is to examine the tools used by the architects and investigate the purposefulness and potential of using their solutions in Polish large-scale prefabricated housing estates. Combining the categories of luxury and saving in redevelopment of housing estates paves the way for a new outlook. Maximizing living space, quality, and freedom of living in housing facilities that are not part of the commercial luxury segment of the housing market may prevent potential gentrification and homogenization of the social structure in individual city districts.
Detectability of the Critically Endangered Araucaria angustifolia Tree Using Worldview-2 Images, Google Earth Engine and UAV-LiDAR
Authors: Saad Felipe , Biswas Sumalika , Huang Qiongyu , Corte Ana Paula Dalla , Coraiola Márcio , Macey Sarah , Carlucci Marcos Bergmann , Leimgruber Peter
Published: December 2021

The Brazilian Atlantic Forest is a global biodiversity hotspot and has been extensively mapped using satellite remote sensing. However, past mapping focused on overall forest cover without consideration of keystone plant resources such as Araucaria angustifolia. A. angustifolia is a critically endangered coniferous tree that is essential for supporting overall biodiversity in the Atlantic Forest. A. angustifolia’s distribution has declined dramatically because of overexploitation and land-use changes. Accurate detection and rapid assessments of the distribution and abundance of this species are urgently needed. We compared two approaches for mapping Araucaria angustifolia across two scales (stand vs. individual tree) at three study sites in Brazil. The first approach used Worldview-2 images and Random Forest in Google Earth Engine to detect A. angustifolia at the stand level, with an accuracy of >90% across all three study sites. The second approach relied on object identification using UAV-LiDAR and successfully mapped individual trees (producer’s/user’s accuracy = 94%/64%) at one study site. Both approaches can be employed in tandem to map remaining stands and to determine the exact location of A. angustifolia trees. Each approach has its own strengths and weaknesses, and we discuss their adoptability by managers to inform conservation of A. angustifolia.
How Does the Concept of Resilient City Work in Practice? Planning and Achievements
Authors: Wang Chuan , Li Xinhua , Li Siheng
Published: December 2021

In the past decade, resilient cities (RCs) have gained extensive attention in academic and political debates as a vision of urban futures. In particular, with the support of the Rockefeller Foundation’s Resilient City 100 Program (RC100), a number of cities worldwide have pushed this concept forward from theory to practice through their RC plans/strategies. However, there is widespread doubt regarding how much this holistic idea of the future built environment contributes to urban practice. After developing a scoring evaluation matrix based on the synthesis of existing RC assessment frameworks, this review scrutinizes the plans, reports, city leaders’ speeches, official websites and academic reviews of five representative resilient cities and investigates their motivations, planning and achievements. The results demonstrate a huge theoretical and practical gap in RC: while RC plans attempt to expand as comprehensively as possible from cities’ initially narrow motivations, their achievements in implementation are limited. Although RC provides more holistic solutions to the cities, the limited resources mean that cities have to prioritize their urgent issues in their everyday practice. This paper calls for designating more feasible and specific features in RC visions and maintaining regular alignments from planning to actions in future RC practice.
Differential Effect of Light and Dark Period Sleep Fragmentation on Composition of Gut Microbiome and Inflammation in Mice
Authors: Sanford Larry , Wellman Laurie , Ciavarra Richard , Oldfield Edward , Shams Rouzbeh , Copare Jennifer , Johnson David
Published: December 2021

Bi-directional interactions amongst the gut microbiota, immune system, and brain function are thought to be critical mediators of health and disease. The role sleep plays in mediating these interactions is not known. We assessed the effects of sleep fragmentation (SF) on the microbiota–gut–brain axis. Male C57BL/6NCrl mice (4 to 5 per cage, fed standard lab chow) experienced SF via mechanical stimulation at 2 min intervals during the light (SF) and dark (DD, dark disturbances) periods. Home cage (HC) controls were undisturbed. After 10 days, fecal samples were collected at light onset, midday, light offset, and midnight. Samples were also collected after 10 days without SF. Subsequently, the mice were randomized across groups and allowed 20 additional days of recovery followed by 10 days of SF or DD. To assess effects on the microbiota, 16S rRNA sequencing was used, and mesenteric lymph nodes (MLNs) and cortex and medial prefrontal cortex were analyzed using cytokine arrays. SF and DD produced significant alterations in the microbiota compared to HC, and DD had greater impact than SF on some organisms. SF produced marked suppression in MLNs of chemokines that regulate inflammation (CCL3, CCL4 and their receptor CCR5) and maintain the immune mucosal barrier (Cxcl13) at the same time that cortical cytokines (IL-33) indicated neuroinflammation. DD effects on immune responses were similar to HC. These data suggest that SF alters the microbiome and suppresses mucosal immunity at the same time that mediators of brain inflammation are upregulated. The translational implications for potential application to clinical care are compelling.
Chromatography-Free Purification Strategies for Large Biological Macromolecular Complexes Involving Fractionated PEG Precipitation and Density Gradients
Authors: Henneberg Fabian , Chari Ashwin
Published: December 2021

A complex interplay between several biological macromolecules maintains cellular homeostasis. Generally, the demanding chemical reactions which sustain life are not performed by individual macromolecules, but rather by several proteins that together form a macromolecular complex. Understanding the functional interactions amongst subunits of these macromolecular machines is fundamental to elucidate mechanisms by which they maintain homeostasis. As the faithful function of macromolecular complexes is essential for cell survival, their mis-function leads to the development of human diseases. Furthermore, detailed mechanistic interrogation of the function of macromolecular machines can be exploited to develop and optimize biotechnological processes. The purification of intact macromolecular complexes is an essential prerequisite for this; however, chromatographic purification schemes can induce the dissociation of subunits or the disintegration of the whole complex. Here, we discuss the development and application of chromatography-free purification strategies based on fractionated PEG precipitation and orthogonal density gradient centrifugation that overcomes existing limitations of established chromatographic purification protocols. The presented case studies illustrate the capabilities of these procedures for the purification of macromolecular complexes.
The Effect of High-Dose-Rate Pulsed Radiation on the Survival of Clinically Relevant Radioresistant Cells
Authors: Terashima Shingo , Yoshino Hironori , Kuwahara Yoshikazu , Sakuraba Hiro , Hosokawa Yoichiro
Published: December 2021

We demonstrated that low dose pulsed radiation (0.25 Gy) at a high-dose-rate, even for very short intervals (10 s), decreases cell survival to a greater extent than single exposure to a similar total dose and dose rate. The objective of this study was to clarify whether high-dose-rate pulsed radiation is effective against SAS-R, a clinically relevant radioresistant cell line. Cell survival following high-dose-rate pulsed radiation was evaluated via a colony assay. Flow cytometry was utilized to evaluate γH2AX, a molecular marker of DNA double-strand breaks and delayed reactive oxygen species (ROS) associated with radiation-induced apoptosis. Increased cytotoxicity was observed in SAS-R and parent SAS cells in response to high dose rate pulsed radiation compared to single dose, as determined by colony assays. Residual γH2AX in both cells subjected to high-dose-rate pulsed radiation showed a tendency to increase, with a significant increase observed in SAS cells at 72 h. In addition, high-dose-rate pulsed radiation increased delayed ROS more than the single exposure did. These results indicate that high-dose-rate pulsed radiation was associated with residual γH2AX and delayed ROS, and high-dose-rate pulsed radiation may be used as an effective radiotherapy procedure against radioresistant cells.
Roles of NAD(P)H:quinone Oxidoreductase 1 in Diverse Diseases
Authors: Lee Wang-Soo , Ham Woojin , Kim Jaetaek
Published: December 2021

NAD(P)H:quinone oxidoreductase (NQO) is an antioxidant flavoprotein that catalyzes the reduction of highly reactive quinone metabolites by employing NAD(P)H as an electron donor. There are two NQO enzymes—NQO1 and NQO2—in mammalian systems. In particular, NQO1 exerts many biological activities, including antioxidant activities, anti-inflammatory effects, and interactions with tumor suppressors. Moreover, several recent studies have revealed the promising roles of NQO1 in protecting against cardiovascular damage and related diseases, such as dyslipidemia, atherosclerosis, insulin resistance, and metabolic syndrome. In this review, we discuss recent developments in the molecular regulation and biochemical properties of NQO1, and describe the potential beneficial roles of NQO1 in diseases associated with oxidative stress.
Exploring the Clinical Utility of Gustatory Dysfunction (GD) as a Triage Symptom Prior to Reverse Transcription Polymerase Chain Reaction (RT-PCR) in the Diagnosis of COVID-19: A Meta-Analysis and Systematic Review
Authors: Pang Khang Wen , Tham Sher-Lyn , Ng Li Shia
Published: December 2021

Background: The diagnosis of COVID-19 is made using reverse transcription polymerase chain reaction (RT-PCR) but its sensitivity varies from 20 to 100%. The presence of gustatory dysfunction (GD) in a patient with upper respiratory tract symptoms might increase the clinical suspicion of COVID-19. Aims: To perform a systematic review and meta-analysis to determine the pooled sensitivity, specificity, positive likelihood ratio (LR+), negative likelihood ratio (LR−) and diagnostic odds ratio (DOR) of using GD as a triage symptom prior to RT-PCR. Methods: PubMed and Embase were searched up to 20 June 2021. Studies published in English were included if they compared the frequency of GD in COVID-19 adult patients (proven by RT-PCR) to COVID-19 negative controls in case control or cross-sectional studies. The Newcastle-Ottawa scale was used to assess the methodological quality of the included studies. Results: 21,272 COVID-19 patients and 52,298 COVID-19 negative patients were included across 44 studies from 21 countries. All studies were of moderate to high risk of bias. Patients with GD were more likely to test positive for COVID-19: DOR 6.39 (4.86–8.40), LR+ 3.84 (3.04–4.84), LR− 0.67 (0.64–0.70), pooled sensitivity 0.37 (0.29–0.47) and pooled specificity 0.92 (0.89–0.94). While history/questionnaire-based assessments were predictive of RT-PCR positivity (DOR 6.62 (4.95–8.85)), gustatory testing was not (DOR 3.53 (0.98–12.7)). There was significant heterogeneity among the 44 studies (I2 = 92%, p < 0.01). Conclusions: GD is useful as a symptom to determine if a patient should undergo further testing, especially in resource-poor regions where COVID-19 testing is scarce. Patients with GD may be advised to quarantine while repeated testing is performed if the initial RT-PCR is negative. Funding: None.
Using Telemedicine to Provide Education for the Symptomatic Patient with Chronic Respiratory Disease
Authors: Blackstock Felicity C. , Roberts Nicola J.
Published: December 2021

Technology-enabled learning, using computers, smartphones, and tablets, to educate patients on their respiratory disease and management has grown over the last decade. This shift has been accelerated by the global COVID-19 pandemic and the need to socially distance for public health. Thirteen recently published papers examined experience, knowledge, skills and attitude acquisition, behaviour change, and impact on health outcomes of patient education using technology (websites and mobile device applications) for people with chronic respiratory disease. Technology-enabled patient education that includes relevant information, with activities that encourage the patient to interact with the digital platform, appears to lead to better patient experience and may increase learning and behaviour change with improved quality of life. Developing online relationships with healthcare providers, lower digital capabilities, and poor access to a computer/smartphone/tablet, appear to be barriers that need to be overcome for equity in access. Maintaining the principles of quality educational design, ensuring interactive experiences for patient involvement in the educational activities, patient co-design, healthcare professionals connecting with experts in the field of technology-enabled learning for development of education models, and ongoing research lead to the best patient outcomes in technology-enabled education for respiratory disease.
Linking In Vitro Models of Endothelial Dysfunction with Cell Senescence
Authors: Jimenez Trinidad Francisco R. , Arrieta Ruiz Marta , Solanes Batlló Núria , Vea Badenes Àngela , Bobi Gibert Joaquim , Valera Cañellas Antoni , Roqué Moreno Mercè , Freixa Rofastes Xavier , Sabaté Tenas Manel , Dantas Ana Paula , Tura-Ceide Olga , Rigol Muxart Montserrat
Published: December 2021

Endothelial cell dysfunction is the principal cause of several cardiovascular diseases that are increasing in prevalence, healthcare costs, and mortality. Developing a standardized, representative in vitro model of endothelial cell dysfunction is fundamental to a greater understanding of the pathophysiology, and to aiding the development of novel pharmacological therapies. We subjected human umbilical vein endothelial cells (HUVECs) to different periods of nutrient deprivation or increasing doses of H2O2 to represent starvation or elevated oxidative stress, respectively, to investigate changes in cellular function. Both in vitro cellular models of endothelial cell dysfunction-associated senescence developed in this study, starvation and oxidative stress, were validated by markers of cellular senescence (increase in β-galactosidase activity, and changes in senescence gene markers SIRT1 and P21) and endothelial dysfunction as denoted by reductions in angiogenic and migratory capabilities. HUVECs showed a significant H2O2 concentration-dependent reduction in cell viability (p < 0.0001), and a significant increase in oxidative stress (p < 0.0001). Furthermore, HUVECs subjected to 96 h of starvation, or exposed to concentrations of H2O2 of 400 to 1000 μM resulted in impaired angiogenic and migratory potentials. These models will enable improved physiological studies of endothelial cell dysfunction, and the rapid testing of cellular efficacy and toxicity of future novel therapeutic compounds.
Comparative Genome Analysis of Streptococcus suis Serotype 9 Isolates from China, The Netherland, and the U.K.
Authors: Yang Huanhuan , Huang Jingjing , Hu Xiaotong , Hu Min , Zhang Qiang , Jin Meilin
Published: December 2021

Streptococcus suis (S. suis) is an important swine pathogen and an emerging zoonotic agent worldwide. Serotype 9 is the most prevalent serotype in several European countries but it is relatively rare in China. In this study, through the investigation of the serotypes of 279 S. suis strains isolated from China from 2015 to 2017, it was found that serotype 9 is the second most prevalent serotype (43 out of 279), behind serotype 2 (83 out of 279). Next, the 43 serotype 9 isolates were sequenced and compared with those from the Netherland (28) and the U.K. (eight). For the purpose of comparison, the strain D12 (GCA_000231905), which has completed genome sequences, was also incorporated. Phylogenetic tree analysis showed that the strains from China and the U.K. were heterogeneous. In contrast, all but one from the Netherland belonged to the same clade. The dominant clades of Chinese strains (33) and strains from the Netherland (27) were very similar. Both of them may have originated from the same strain about 70 years ago. Then, the distributions of virulence-associated genes and antibiotic resistance genes among different clades and sources were analyzed. By comparison, strains from the Netherland carried more virulence-associated genes and those from the U.K. had more antibiotic resistance genes. Additionally, some virulence-associated genes (salK and salR) and antibiotic resistance genes (lincomycin and spectinomycin) existed only in several Chinese strains. In conclusion, our data displayed the population characteristics and differences of S. suis serotype 9 between China and Europe, suggesting that they have taken different evolutionary paths.
Brown Fat Dnmt3b Deficiency Ameliorates Obesity in Female Mice
Authors: Li Fenfen , Cui Xin , Jing Jia , Wang Shirong , Shi Huidong , Xue Bingzhong , Shi Hang
Published: December 2021

Obesity results from a chronic energy imbalance due to energy intake exceeding energy expenditure. Activation of brown fat thermogenesis has been shown to combat obesity. Epigenetic regulation, including DNA methylation, has emerged as a key regulator of brown fat thermogenic function. Here we aimed to study the role of Dnmt3b, a DNA methyltransferase involved in de novo DNA methylation, in the regulation of brown fat thermogenesis and obesity. We found that the specific deletion of Dnmt3b in brown fat promotes the thermogenic and mitochondrial program in brown fat, enhances energy expenditure, and decreases adiposity in female mice fed a regular chow diet. With a lean phenotype, the female knockout mice also exhibit increased insulin sensitivity. In addition, Dnmt3b deficiency in brown fat also prevents diet-induced obesity and insulin resistance in female mice. Interestingly, our RNA-seq analysis revealed an upregulation of the PI3K-Akt pathway in the brown fat of female Dnmt3b knockout mice. However, male Dnmt3b knockout mice have no change in their body weight, suggesting the existence of sexual dimorphism in the brown fat Dnmt3b knockout model. Our data demonstrate that Dnmt3b plays an important role in the regulation of brown fat function, energy metabolism and obesity in female mice.
Sex-Specific Social Effects on Depression-Related Behavioral Phenotypes in Mice
Authors: Patel Seona , Cameron Lindsay , Olson David
Published: December 2021

Social interaction and empathy play critical roles in determining the emotional well-being of humans. Stress-related depression and anxiety can be exacerbated or mitigated depending on specific social conditions. Although rodents are well known to exhibit emotional contagion and consolation behavior, the effects of group housing on stress-induced phenotypes in both males and females are not well established. Here, we investigated how the presence of stressed or unstressed conspecifics within a cage impact depression-related phenotypes. We housed male and female C57BL/6J mice in same-sex groups and subjected them to either gentle handling (GH) or the daily administration of corticosterone (CORT) for 10 days. The GH and CORT treatment groups were divided into cages of unmixed (GH or CORT) and mixed (GH and CORT) treatments. Depression-related phenotypes were measured using the forced swim test (FST) and sucrose preference test (SPT). We found that mixed housing alters FST behavior in a sex-specific manner. Male mice given chronic corticosterone (CORT) that were housed in the same cage as gently handled animals (GH) exhibited increased immobility, whereas GH females housed with CORT females demonstrated the opposite effect. This study underscores the importance of social housing conditions when evaluating stress-induced behavioral phenotypes and suggests that mixed cages of GH and CORT animals yield the greatest difference between treatment groups. The latter finding has important implications for identifying therapeutics capable of rescuing stress-induced behavioral deficits in the FST.
Salivary Microbiota Is Significantly Less Diverse in Patients with Chronic Spontaneous Urticaria Compared to Healthy Controls: Preliminary Results
Authors: Ćesić Diana , Lugović-Mihić Liborija , Ferček Iva , Grginić Ana Gverić , Jelić Marko , Bešlić Iva , Tambić Andrašević Arjana
Published: December 2021

Background: Because of the important role in regulating the immune system, increasing evidence suggests a possible implication of gut microbiota in Chronic spontaneous urticaria (CSU). Although the oral cavity is the first site of contact between microbiota and the immune system, the association between salivary microbiota and CSU has not yet been reported. Objective: This case-control study aimed to compare differences in salivary microbiota between CSU patients and healthy controls (HC). Twenty-three participants—13 patients with CSU and 10 HC were enrolled; salivary microbiota was determined by molecular approach targeting 16S ribosomal RNA. Terminal restriction fragment length polymorphism (T-RFLP) analysis was performed. Results: Alpha diversity of salivary microbiota in CSU patients was significantly reduced compared to HC, resulting in alteration of the community composition. Species richness determined via the Shannon index was significantly reduced in the CSU group. Conclusion: Dysbiosis of salivary microbiota may contribute to a dysregulated immune system in the development of CSU. To our knowledge, this was the first study that reported an alteration in salivary microbiota composition in CSU patients.
Structural, Electromagnetic and Microwave Properties of Magnetite Extracted from Mill Scale Waste via Conventional Ball Milling and Mechanical Alloying Techniques
Authors: Elmahaishi Madiha Fathi , Azis Raba’ah Syahidah , Ismail Ismayadi , Mustaffa Muhammad Syazwan , Abbas Zulkifly , Matori Khamirul Amin , Muhammad Farah Diana , Saat Nor Kamilah , Nazlan Rodziah , Ibrahim Idza Riati , Abdullah Nor Hapishah , Mokhtar Nurhidayaty
Published: December 2021

This study presents the utilization of mill scale waste, which has attracted much attention due to its high content of magnetite (Fe3O4). This work focuses on the extraction of Fe3O4 from mill scale waste via magnetic separation, and ball milling was used to fabricate a microwave absorber. The extracted magnetic powder was ground-milled using two different techniques: (i) a conventional milling technique (CM) and (ii) mechanical alloying (MM) process. The Fe3O4/CM samples were prepared by a conventional milling process using steel pot ball milling, while the Fe3O4/MM samples were prepared using a high-energy ball milling (HEBM) method. The effect of milling time on the structural, phase composition, and electromagnetic properties were examined using X-ray diffraction (XRD) and a vector network analyzer (VNA). XRD confirmed the formation of magnetite after both the magnetic separation and milling processes. The results revealed that Fe3O4 exhibited excellent microwave absorption properties because of the synergistic characteristics of its dielectric and magnetic loss. The results showed that the Fe3O4/CM particle powder had a greater absorption power (reflection loss: <−10 dB) with 99.9% absorption, a minimum reflection loss of −30.83 dB, and an effective bandwidth of 2.30 GHz for 2 mm thick samples. The results revealed the Fe3O4/MM powders had higher absorption properties, including a higher RL of −20.59 dB and a broader bandwidth of 2.43 GHz at a matching thickness of only 1 mm. The higher microwave absorption performance was attributed to the better impedance matching property caused by the porous microstructure. Furthermore, the magnetite, Fe3O4 showed superior microwave absorption characteristics because of the lower value of permittivity, which resulted in better impedance matching. This study presents a low-cost approach method by reutilizing mill scale waste to fabricate a high purity crystalline Fe3O4 with the best potential for designing magnetic nano-sized based microwave absorbers.
An Analysis of Kikuchi Lines Observed with a RHEED Apparatus for a TiO2-Terminated SrTiO3 (001) Crystal
Authors: Pawlak Jakub , Przybylski Marek , Mitura Zbigniew
Published: December 2021

In this study, electron diffraction patterns observed under high vacuum conditions for an SrTiO3 surface were interpreted in detail while paying special attention to the features of inelastic effects. The surface of the SrTiO2 was carefully prepared to enforce its termination with single domains of TiO2 layers at the top. The inelastic patterns were interpreted using analytical models. Two types of Kikuchi lines are recognized in this paper: those which can be described with the Bragg law and those which appear due to surface wave resonance effects. However, we also discuss that there exists a formal connection between the two types of the Kikuchi lines observed.
Moldable Mask: A Reusable, Hot Water Moldable, Additively Manufactured Mask to Be Used as an N95 Alternative
Authors: Martelly Erica , Li Charles , Shimada Kenji
Published: December 2021

There has been high demand for personal protective equipment (PPE) during the COVID-19 pandemic, especially N95 respirators. Unfortunately, at the early stage of the pandemic, the supply could not meet the demand for N95 respirators, leading to a shortage and unsafe reuse of this form of PPE. We developed the Moldable Mask to ease the demand for N95 respirators by creating a 3D-printed mask that uses a piece of N95 material as a filter. A sheet of N95 material could be used or one N95 respirator to be turned into two masks. The main feature of the mask is the ability to easily mold it in hot water to create a custom fit for each user. It can also be easily assembled at home with affordable materials. The final mask design was qualitatively fit tested on 13 subjects, with all subjects showing an improvement in fit with the hot water molding technique and 10 (77%) subjects passing the fit test. This shows that the Moldable Mask is a viable option for a safe, affordable N95 alternative when N95 mask supply is strained.
Abrasive Wear, Scuffing and Rolling Contact Fatigue of DLC-Coated 18CrNiMo7-6 Steel Lubricated by a Pure and Contaminated Gear Oil
Authors: Tuszyński Waldemar , Michalczewski Remigiusz , Osuch-Słomka Edyta , Snarski-Adamski Andrzej , Kalbarczyk Marek , Wieczorek Andrzej N. , Nędza Jakub
Published: December 2021

Due to extreme working conditions of mining conveyors, which contaminate gear oil with solid particles, their transmissions are exposed to intensive abrasion, scuffing, and even rolling contact fatigue (pitting). These effects shorten gear life. To prevent their occurrence, a wear-resistant coating can be deposited on gear teeth. The resistance to abrasive wear, scuffing, and pitting was investigated and reported in the article. Simple, model specimens were used. Abrasive wear and scuffing were tested using a pin-and-vee-block tribosystem in sliding contact. A cone–three-ball rolling tribosystem was employed to test pitting. The material of the test specimens (pins, vee blocks, cones) was 18CrNiMo7-6 case-hardened steel. Two types of DLC (Diamond-like Coatings) coatings were tested, W-DLC and W-DLC/CrN. The vee blocks and cones were coated. Two industrial gear oils were selected to lubricate the specimens: one with a mineral and one with a synthetic PAO (polyalphaolephine) base, as pure oil or contaminated with solid particles from a coal mine. The results show that, to minimize the tendency to abrasion, scuffing, and pitting of specimens made of 18CrNiMo7-6 steel, the W-DLC/CrN coating should be deposited. This coating also gives very good protection when the lubricating oil is contaminated.
Three-Dimensional Solution for the Vibration Analysis of Functionally Graded Rectangular Plate with/without Cutouts Subject to General Boundary Conditions
Authors: Huang Wenhao , Xue Kai , Li Qiuhong
Published: December 2021

Functionally graded materials (FGMs) structures are increasingly used in engineering due to their superior mechanical and material properties, and the FGMs plate with cutouts is a common structural form, but research on the vibration characteristics of FGMs plate with cutouts is relatively limited. In this paper, the three-dimensional exact solution for the vibration analysis of FGMs rectangular plate with circular cutouts subjected to general boundary conditions is presented based on the three-dimensional elasticity theory. The displacement field functions are expressed as standard cosine Fourier series plus auxiliary cosine series terms satisfying the boundary conditions in the global coordinate system. The plate with circular cutout is discretized into four curve quadrilateral sub-domains using the p-version method, and then the blending function method is applied to map the closed quadrilateral region to the computational space. The characteristic equation is obtained based on the Lagrangian energy principle and Rayleigh–Ritz method. The efficiency and reliability of proposed method are verified by comparing the present results with those available in the literature and FEM methods. Finally, a parametric study is investigated including the cutout sizes, the cutout positions, and the cutout numbers from the free vibration characteristic analysis and the harmonic analysis. The results can serve as benchmark data for other research on the vibration of FGMs plates with cutouts.
Structure and Thermal Expansion of Cu−90 vol. % Graphite Composites
Authors: Opálek Andrej , Emmer Štefan , Čička Roman , Beronská Naďa , Oslanec Peter , Kováčik Jaroslav
Published: December 2021

Copper–graphite composites are promising functional materials exhibiting application potential in electrical equipment and heat exchangers, due to their lower expansion coefficient and high electrical and thermal conductivities. Here, copper–graphite composites with 10–90 vol. % graphite were prepared by hot isostatic pressing, and their microstructure and coefficient of thermal expansion (CTE) were experimentally examined. The CTE decreased with increasing graphite volume fraction, from 17.8 × 10−6 K−1 for HIPed pure copper to 4.9 × 10−6 K−1 for 90 vol. % graphite. In the HIPed pure copper, the presence of cuprous oxide was detected by SEM-EDS. In contrast, Cu–graphite composites contained only a very small amount of oxygen (OHN analysis). There was only one exception, the composite with 90 vol. % graphite contained around 1.8 wt. % water absorbed inside the structure. The internal stresses in the composites were released during the first heating cycle of the CTE measurement. The permanent prolongation and shape of CTE curves were strongly affected by composition. After the release of internal stresses, the CTE curves of composites did not change any further. Finally, the modified Schapery model, including anisotropy and the clustering of graphite, was used to model the dependence of CTE on graphite volume fraction. Modeling suggested that the clustering of graphite via van der Waals bonds (out of hexagonal plane) is the most critical parameter and significantly affects the microstructure and CTE of the Cu–graphite composites when more than 30 vol. % graphite is present.
The Analysis of Polyethylene Hip Joint Endoprostheses Strength Parameters Changes after Use inside the Human Body
Authors: Szarek Arkadiusz , Postawa Przemysław , Stachowiak Tomasz , Paszta Piotr , Redutko Joanna , Mordal Katarzyna , Kalwik Aleksandra , Łukomska-Szarek Justyna , Gzik Marek , Joszko Kamil , Rydz Dariusz , Łągiewka Małgorzata , Gzik-Zroska Bożena
Published: December 2021

The influence of dynamic loads resulting from human motor activity and electrocorrosion inside the human body on the strength parameters of artificial joint elements has not yet been investigated. Hip joint arthroplasty is the most common surgical procedure in the world that allows doctors to remove pain and restore motor skills in people with severe hip diseases, after accidents, and in the elderly. Based on the reports, this article assesses changes in the number of implanted endoprostheses in the years 2005–2019 and determines the trends and estimated changes in the number of implanted hip prostheses in the following decades. The study assesses changes in selected strength parameters of UHMW-PE polyethylene inserts of hip joint endoprostheses during their use in the human body. The research was carried out on appropriately collected samples from UHMW-PE cups removed from the human body with a known history and lifetime from 4 to 10 years. Patients’ body weight ranged from 735 [N] to 820 [N], and the declared physical activity was similar in the entire research group. As part of the research, the values of changes in dynamic modules and the mechanical loss coefficient were determined in relation to the share of the crystalline and amorphous phases of artificial UHMW-PE cups, removed from the human body after different periods of exploitation under similar operating conditions. The analysis of selected strength parameters was performed at a temperature of 40 °C, which corresponds to the working conditions inside the human body. On the basis of numerical studies, the influence of changes in material parameters on the deformation of the artificial acetabulum during the patient’s motor activity, which is one of the causes of fatigue destruction, was determined.
Corrosion Behavior of the CoNiCrAlY-Al2O3 Composite Coating Based on Core-Shell Structured Powder Design
Authors: Guo Wenmin , Zhang Honglin , Zhao Shan , Ding Zhibing , Liu Bin , Li Wenjuan , Xu Huanhuan , Liu Huiyuan
Published: December 2021

The oxidation of the metal powder during the thermal spraying process usually leads to significant deterioration of the microstructure and performance of the coating. In order to isolate the metal powder from oxygen during the spraying process, the CoNiCrAlY-Al2O3 core-shell structured powder with Al2O3 as the shell was designed in this study. The influence of the core-shell structured powder on the microstructure and corrosion resistance of the HVOF coating has been studied in detail. The results show that the temperature field of the molten CoNiCrAlY powder during the spraying process is significantly changed by the Al2O3 shell. The poor deformability of the CoNiCrAlY-Al2O3 droplets leads to an increase in the porosity and unmelted particles of the coating. In addition, the significant difference is that the coating also maintains a high content of β-NiAl phase. The lower oxide content in the CoNiCrAlY-Al2O3 coating indicates that the core-shell structured powder significantly inhibits the oxidation of the CoNiCrAlY core powder during the spraying process. The CoNiCrAlY-Al2O3 coating exhibits high corrosion potential, passive film resistance, charge transfer resistance, and low corrosion current density in 3.5 wt.% NaCl solution, indicating that the coating has excellent corrosion resistance.
Structures 4-n-propyl Piperazines as Non-Imidazole Histamine H3 Antagonists
Authors: Olczak Andrzej , Sukiennik Jarosław , Olszewska Beata , Stefaniak Monika , Walczyński Krzysztof , Szczesio Małgorzata
Published: December 2021

Seven new low-temperature structures of 4-n-propylpiperazine derivatives, potential H3 receptor antagonists, have been determined by X-ray crystallography, with the following symmetry and unit cell parameters: 2-(4-propyl-piperazin-1-yl)oxazolo[4,5-c]pyridine (compound 1), P-1, 5.9496 Å, 12.4570 Å, 12.8656 Å, 112.445°, 95.687°, 103.040°; 2-(4-propyl-piperazin-1-yl)thia-zolo[4,5-c]pyridine (compound 2), I2/a, 22.2087 Å, 7.5519 Å, 19.9225 Å, β = 92.368°; 2-(4-propyl-piperazin-1-yl)oxazolo[5,4-c]pyridine (compound 3), C2/c, 51.1351 Å, 9.36026 Å, 7.19352 Å, β = 93.882°; 2-(4-propyl-piperazin-1-yl)thiazolo[5,4-c]pyridine (compound 4), Pbcn, 19.2189 Å, 20.6172 Å, 7.4439 Å; 2-(4-propylpiperazin-1-yl)[1,3]oxazolo[4,5-b]pyridine, hydrate (structure 5), Pbca, 7.4967 Å, 12.2531 Å, 36.9527 Å; 2-(4-propylpiperazin-1-yl)[1,3]oxazolo[4,5-b]pyridine, first polymorph (structure 6), P-1, 7.2634 Å, 11.1261 Å, 18.5460 Å, 80.561°, 80.848°, 76.840°; 2-(4-propylpiperazin-1-yl)[1,3]oxazolo[4,5-b]pyridine, second polymorph (structure 7), P21, 8.10852 Å, 7.06025 Å, 12.41650 Å, β = 92.2991°. All the compounds crystallized out as hydrobromides. Oxazole structures show a much greater tendency to form twin crystals than thiazole structures. All the investigated structures display N—H···Br hydrogen bonding. (ADME) analysis, including the assessment of absorption, distribution, metabolism, and excretion, determined the physicochemical properties, pharmacokinetics, drug similarity, and bioavailability radar, and confirmed the usefulness of the compounds in question for pharmaceutical utility. This work is a continuation of the research searching for a new lead of non-imidazole histamine H3 receptor antagonists.
Gene-Activated Matrix with Self-Assembly Anionic Nano-Device Containing Plasmid DNAs for Rat Cranial Bone Augmentation
Authors: Hara Masahito , Sumita Yoshinori , Kodama Yukinobu , Iwatake Mayumi , Yamamoto Hideyuki , Shido Rena , Narahara Shun , Ogaeri Takunori , Sasaki Hitoshi , Asahina Izumi
Published: December 2021

We have developed nanoballs, a biocompatible self-assembly nano-vector based on electrostatic interactions that arrange anionic macromolecules to polymeric nanomaterials to create nucleic acid carriers. Nanoballs exhibit low cytotoxicity and high transfection efficiently in vivo. This study investigated whether a gene-activated matrix (GAM) composed of nanoballs containing plasmid (p) DNAs encoding bone morphogenetic protein 4 (pBMP4) could promote bone augmentation with a small amount of DNA compared to that composed of naked pDNAs. We prepared nanoballs (BMP4-nanoballs) constructed with pBMP4 and dendrigraft poly-L-lysine (DGL, a cationic polymer) coated by γ-polyglutamic acid (γ-PGA; an anionic polymer), and determined their biological functions in vitro and in vivo. Next, GAMs were manufactured by mixing nanoballs with 2% atelocollagen and β-tricalcium phosphate (β-TCP) granules and lyophilizing them for bone augmentation. The GAMs were then transplanted to rat cranial bone surfaces under the periosteum. From the initial stage, infiltrated macrophages and mesenchymal progenitor cells took up the nanoballs, and their anti-inflammatory and osteoblastic differentiations were promoted over time. Subsequently, bone augmentation was clearly recognized for up to 8 weeks in transplanted GAMs containing BMP4-nanoballs. Notably, only 1 μg of BMP4-nanoballs induced a sufficient volume of new bone, while 1000 μg of naked pDNAs were required to induce the same level of bone augmentation. These data suggest that applying this anionic vector to the appropriate matrices can facilitate GAM-based bone engineering.
Thin-Walled Cylindrical Shell Storage Tank under Blast Impacts: Finite Element Analysis
Authors: Al-Yacouby Ahmad Mahamad , Hao Lo Jia , Liew M. S. , Ratnayake R. M. Chandima , Samarakoon Samindi M. K.
Published: December 2021

Thin-walled cylindrical shell storage tanks are pressure vessels in which the walls of the vessel have a thickness that is much smaller than the overall size of the vessel. These types of structures have global applications in various industries, including oil refineries and petrochemical plants. However, these storage tanks are vulnerable to fire and explosions. Therefore, a parametric study using numerical simulation was carried out, considering the internal liquid level, wall thickness, material yield strength, constraint conditions, and blast intensity, with a diameter of 100 m and height of 22.5 m under different blast loads using the finite element analysis method. The thickness of the tank wall is varied as 10 mm, 20 mm, 30 mm, and 40 mm, while the fill level of internal fluid is varied as 25, 50, 75, and 100%. The blast simulation was conducted using LS-DYNA software. The numerical results are then compared with analytical results. The effects of blast intensity, standoff distance, wall thickness, and fill level of internal fluid on the structural behaviour of the storage tank were investigated and discussed.
Effect of Manufactured Sand with Different Quality on Chloride Penetration Resistance of High–Strength Recycled Concrete
Authors: Feng Jincai , Dong Chaoqun , Chen Chunhong , Wang Xinjie , Qian Zhongqiu
Published: December 2021

High–strength manufactured sand recycled aggregate concrete (MSRAC) prepared with manufactured sand (MS) and recycled coarse aggregate (RCA) is an effective way to reduce the consumption of natural aggregate resources and environmental impact of concrete industry. In this study, high–, medium– and low–quality MS, which were commercial MS local to Changzhou and 100% by volume of recycled coarse aggregate, were used to prepare MSRAC. The quality of MS was determined based on stone powder content, methylene blue value (MBV), crushing value and soundness as quality characteristic parameters. The variation laws of compressive strength and chloride penetration resistance of high–strength MSRAC with different rates of replacement and different qualities of MS were explored. The results showed that for medium– and low–quality MS, the compressive strength of the MSRAC increased first and then decreased with increasing rate of replacement. Conversely, for high–quality MS, the compressive strength gradually increased with increasing rate of replacement. The chloride diffusion coefficient of MSRAC increased with decreasing MS quality and increasing rate of replacement. The chloride diffusion coefficient of MSRAC basically met the specifications for 50–year and 100–year design working life when the chloride environmental action was D and E. To prepare high–strength MSRAC, high–quality MS can 100% replace RS (river sand), while rates of replacement of 50–75% for medium–quality MS or 25–50% for low–quality MS are proposed. Scanning Electron Microscope (SEM) images indicated that an appropriate amount of stone powder is able to improve the compressive strength of RAC, but excessive stone powder content and MBV are unfavorable to the compressive strength and chloride penetration resistance of RAC.
Twinning-Induced Abnormal Strain Rate Sensitivity and Indentation Creep Behavior in Nanocrystalline Mg Alloy
Authors: Yu Shilun , Wan Yingchun , Liu Chuming , Chen Zhiyong , Zhou Xiangyang
Published: December 2021

Nanocrystalline materials exhibit many unique physical and chemical properties with respect to their coarse-grained counterparts due to the high volume fraction of grain boundaries. Research interests on nanocrystalline materials around the world have been lasting over the past decades. In this study, we explored the room temperature strain rate sensitivity and creep behavior of the nanocrystalline Mg–Gd–Y–Zr alloy by using a nanoindentation technique. Results showed that the hardness and creep displacements of the nanocrystalline Mg–Gd–Y–Zr alloy decreased with increasing loading strain rate. That is, the nanocrystalline Mg–Gd–Y–Zr alloy showed negative strain rate sensitivity and its creep behavior also exhibited negative rate dependence. It was revealed that the enhanced twinning activities at higher loading strain rates resulted in reduced hardness and creep displacements. The dominant creep mechanism of the nanocrystalline Mg–Gd–Y–Zr alloy is discussed based on a work-of-indentation theory in this paper.
An Inverse Method for Measuring Elastoplastic Properties of Metallic Materials Using Bayesian Model and Residual Imprint from Spherical Indentation
Authors: Wang Mingzhi , Wang Weidong
Published: December 2021

In this paper, an inverse method is proposed for measuring the elastoplastic properties of metallic materials using a spherical indentation experiment. In the new method, the elastoplastic parameters are correlated with sub-space coordinates of indentation imprints using proper orthogonal decomposition (POD), and inverse identification of material properties is solved using a statistical Bayesian framework. The advantage of the method is that model parameters in the numerical optimization process are treated as the stochastic variables, and potential uncertainties can be considered. The posterior results obtained from the measuring method can provide valuable probabilistic information of the estimated elastoplastic properties. The proposed method is verified by the application on 2099-T83 Al-Li alloys. Results indicate that posterior distribution of material parameters exhibits more than one peak region when indentation load is not large enough. In addition, using the weighting imprints under different loads can facilitate the uniqueness in identification of elastoplastic parameters. The influence of the weighting coefficient on posterior identification results is analyzed. The elastoplastic properties identified by indentation and tensile experiment show good agreement. Results indicate that the established measuring method is effective and reliable.