bluuebunny/crossref_metadata_2025 huggingface dataset:
In Vitro Characterization of Dental Pulp Stem Cells Cultured in Two Microsphere-Forming Culture Plates
Authors: Bu Nam-Ung , Lee Hyo-Seol , Lee Bin-Na , Hwang Yun-Chan , Kim Sun-Young , Chang Seok Woo , Choi Kyoung-Kyu , Kim Duck-Su , Jang Ji-Hyun
Published: January 2020

Various three-dimensional (3D) culture methods have been introduced to overcome the limitations of in vitro culture and mimic in vivo conditions. This study aimed to evaluate two microsphere-forming culture methods and a monolayer culture method. We evaluated cell morphology, viability, osteo-, adipo-, and chondrogenic differentiation potential of dental pulp stem cells (DPSCs) cultured in 3D culture plates: ultra-low attachment (ULA) and U-bottomed StemFit 3D (SF) plates, and a two-dimensional (2D) monolayer plate. RNA sequencing (RNA-seq) revealed differentially expressed gene (DEG) profiles of the DPSCs. In contrast to an increasing pattern in the 2D group, cell viability in 3D groups (ULA and SF) showed a decreasing pattern; however, high multilineage differentiation was observed in both the 3D groups. RNA-seq showed significantly overexpressed gene ontology categories including angiogenesis, cell migration, differentiation, and proliferation in the 3D groups. Hierarchical clustering analysis revealed a similar DEG regulation pattern between the 3D groups; however, a comparatively different DEG was observed between the 2D and 3D groups. Taken together, this study shows that DPSCs cultured in microsphere-forming plates present superior multilineage differentiation capacities and demonstrate higher DEG expression in regeneration-related gene categories compared to that in DPSCs cultured in a conventional monolayer plate.
Potential Salivary mRNA Biomarkers for Early Detection of Oral Cancer
Authors: Oh Su Young , Kang Sung-Min , Kang Soo Hyun , Lee Heon-Jin , Kwon Tae-Geon , Kim Jin-Wook , Lee Sung-Tak , Choi So-Young , Hong Su-Hyung
Published: January 2020

We evaluated potential biomarkers in human whole saliva for the early diagnosis of oral squamous cell carcinoma (OSCC). We selected 30 candidate genes with relevance to cancer from recent reports in PubMed. Saliva samples were obtained from 34 non-tumor control and 33 OSCC patients. Real-time PCR was performed, and mRNA levels were compared. Normalized mRNA levels of six genes (NGFI-A binding protein 2 (NAB2), cytochrome P450, family 27, subfamily A, polypeptide 1 (CYP27A1), nuclear pore complex interacting protein family, member B4 (NPIPB4), monoamine oxidase B (MAOB), sialic acid acetyltransferase (SIAE), and collagen, type III, alpha 1 (COL3A1)) were significantly lower in saliva of OSCC patients. Receiver operating characteristics (ROC) analysis was used to individually evaluate the predictive power of the potential biomarkers for OSCC diagnosis. The area under the curve (AUC) values were evaluated for the OSCC vs. non-tumor groups via univariate ROC analyses, as well as multivariate ROC analyses of combinations of multiple potential biomarkers. The combination of CYP27A1 + SIAE showed a favorable AUC value of 0.84. When we divided saliva samples into two groups according to age using a 60-year cut-off, with OSCC patients and controls evaluated together, the AUC of MAOB–NAB2 was more predictive of OSCC in the under-60 group (AUC, 0.91; sensitivity, 0.92; and specificity, 0.86) than any other gene combination. These results are expected to aid the early diagnosis of OSCC, especially in patients under 60 years of age. While more studies with larger numbers of patients are necessary, our result suggest that salivary mRNA would be a potent biomarker for early OSCC diagnosis.
Association between On-Treatment Haemoglobin A1c and All-Cause Mortality in Individuals with Type 2 Diabetes: Importance of Personalized Goals and Type of Anti-Hyperglycaemic Treatment
Authors: Orsi Emanuela , Bonora Enzo , Solini Anna , Fondelli Cecilia , Trevisan Roberto , Vedovato Monica , Cavalot Franco , Zerbini Gianpaolo , Morano Susanna , Nicolucci Antonio , Penno Giuseppe , Pugliese Giuseppe
Published: January 2020

The increased mortality reported with intensive glycaemic control has been attributed to an increased risk of treatment-related hypoglycaemia. This study investigated the relationships of haemoglobin (Hb) A1c, anti-hyperglycaemic treatment, and potential risks of adverse effects with all-cause mortality in patients with type 2 diabetes. Patients (n = 15,773) were stratified into four categories according to baseline HbA1c and then assigned to three target categories, based on whether HbA1c was ≤0.5% below or above (on-target), >0.5% below (below-target) or >0.5% above (above-target) their HbA1c goal, personalized according to the number of potential risks among age > 70 years, diabetes duration > 10 years, advanced complication(s), and severe comorbidity (ies). The vital status was retrieved for 15,656 patients (99.26%). Over a 7.4-year follow-up, mortality risk was increased among patients in the highest HbA1c category (≥8.5%) (adjusted hazard ratio, 1.34 (95% confidence interval, 1.22–1.47), p < 0.001) and those above-target (1.42 (1.29–1.57), p < 0.001). Risk was increased among individuals in the lowest HbA1c category (<6.5%) and those below-target only if treated with agents causing hypoglycaemia (1.16 (1.03–1.29), p = 0.01 and 1.10 (1.01–1.22), p = 0.04, respectively). These data suggest the importance of setting both upper and lower personalized HbA1c goals to avoid overtreatment in high-risk individuals with type 2 diabetes treated with agents causing hypoglycaemia.
Can Artificial Intelligence Improve the Management of Pneumonia
Authors: Chumbita Mariana , Cillóniz Catia , Puerta-Alcalde Pedro , Moreno-García Estela , Sanjuan Gemma , Garcia-Pouton Nicole , Soriano Alex , Torres Antoni , Garcia-Vidal Carolina
Published: January 2020

The use of artificial intelligence (AI) to support clinical medical decisions is a rather promising concept. There are two important factors that have driven these advances: the availability of data from electronic health records (EHR) and progress made in computational performance. These two concepts are interrelated with respect to complex mathematical functions such as machine learning (ML) or neural networks (NN). Indeed, some published articles have already demonstrated the potential of these approaches in medicine. When considering the diagnosis and management of pneumonia, the use of AI and chest X-ray (CXR) images primarily have been indicative of early diagnosis, prompt antimicrobial therapy, and ultimately, better prognosis. Coupled with this is the growing research involving empirical therapy and mortality prediction, too. Maximizing the power of NN, the majority of studies have reported high accuracy rates in their predictions. As AI can handle large amounts of data and execute mathematical functions such as machine learning and neural networks, AI can be revolutionary in supporting the clinical decision-making processes. In this review, we describe and discuss the most relevant studies of AI in pneumonia.
Associated Lichen Sclerosis Increases the Risk of Lymph Node Metastases of Vulvar Cancer
Authors: Dabi Yohann , Gosset Marie , Bastuji-Garin Sylvie , Mitri-Frangieh Rana , Bendifallah Sofiane , Darai Emile , Paniel Bernard Jean , Rouzier Roman , Haddad Bassam , Touboul Cyril
Published: January 2020

The most important prognostic factor in vulvar cancer is inguinal lymph node status at the time of diagnosis, even in locally advanced vulvar tumors. The aim of our study was to identify the risk factors of lymph node involvement in these women, especially the impact of lichen sclerosis (LS). We conducted a retrospective population-based cross-sectional study in two French referral gynecologic oncology institutions. We included all women diagnosed with a primary invasive vulvar cancer. Epithelial alteration adjacent to the invasive carcinoma was found in 96.8% (n = 395). The most frequently associated was LS in 27.7% (n = 113). In univariate analysis, LS (p = 0.009); usual type VIN (p = 0.04); tumor size >2 cm and/or local extension to vagina, urethra or anus (p < 0.01), positive margins (p < 0.01), thickness (p < 0.01) and lymphovascular space invasion (LVSI) (p < 0.01) were significantly associated with lymph node involvement. In multivariate analysis, only LS (OR 2.3, 95% CI [1.2–4.3]) and LVSI (OR 5.6, 95% CI [1.7–18.6]) remained significantly associated with positive lymph node. LS was significantly associated with older patients (p = 0.005), anterior localization (p = 0.017) and local extension (tumor size > 2 cm: p = 0.001). LS surrounding vulvar cancer is an independent factor of lymph node involvement, with local extension and LVSI.
The Effect of Hearing Aid Use on Cognition in Older Adults: Can We Delay Decline or Even Improve Cognitive Function?
Authors: Sarant Julia , Harris David , Busby Peter , Maruff Paul , Schembri Adrian , Lemke Ulrike , Launer Stefan
Published: January 2020

Hearing loss is a modifiable risk factor for dementia in older adults. Whether hearing aid use can delay the onset of cognitive decline is unknown. Participants in this study (aged 62–82 years) were assessed before and 18 months after hearing aid fitting on hearing, cognitive function, speech perception, quality of life, physical activity, loneliness, isolation, mood, and medical health. At baseline, multiple linear regression showed hearing loss and age predicted significantly poorer executive function performance, while tertiary education predicted significantly higher executive function and visual learning performance. At 18 months after hearing aid fitting, speech perception in quiet, self-reported listening disability and quality of life had significantly improved. Group mean scores across the cognitive test battery showed no significant decline, and executive function significantly improved. Reliable Change Index scores also showed either clinically significant improvement or stability in executive function for 97.3% of participants, and for females for working memory, visual attention and visual learning. Relative stability and clinically and statistically significant improvement in cognition were seen in this participant group after 18 months of hearing aid use, suggesting that treatment of hearing loss with hearing aids may delay cognitive decline. Given the small sample size, further follow up is required.
Outcome of Femoral Varus Derotational Osteotomy for the Spastic Hip Displacement: Implication for the Indication of Concomitant Pelvic Osteotomy
Authors: Park Hoon , Abdel-Baki Sharkawy Wagih , Park Kun-Bo , Park Byoung Kyu , Rhee Isaac , Hong Seung-Pyo , Kim Hyun Woo
Published: January 2020

No previous studies have suggested a reliable criterion for determining the addition of a concomitant pelvic osteotomy by using a large patient cohort with quadriplegic cerebral palsy and a homogenous treatment entity of femoral varus derotational osteotomies (VDRO). In this retrospective study, we examined our results of hip reconstructions conducted without a concomitant pericapsular acetabuloplasty in patients with varying degrees of hip displacement. We wished to investigate potential predictors for re-subluxation or re-dislocation after the index operation, and to suggest the indications for a simultaneous pelvic osteotomy. We reviewed the results of 144 VDROs, with or without open reduction, in 72 patients, at a mean follow-up of 7.0 (2.0 to 16.0) years. Various radiographic parameters were measured, and surgical outcomes were assessed based on the final migration percentage (MP) and the Melbourne Cerebral Palsy Hip Classification Scale (MCPHCS) grades. The effects of potential predictive factors on the surgical outcome was assessed by multivariate regression analysis. A receiver operating characteristic (ROC) curve analysis was also performed to determine whether a threshold of each risk factor existed above which the rate of unsatisfactory outcomes was significantly increased. In total, 113 hips (78.5%) showed satisfactory results, classified as MCPHCS grades I, II, and III. Thirty-one hips (21.5%) showed unsatisfactory results, including six hip dislocations. Age at surgery and preoperative acetabular index had no effects on the results. Lower pre- and postoperative MP were found to be the influential predictors of successful outcomes. The inflection point of the ROC curve for unsatisfactory outcomes corresponded to the preoperative MP of 61.8% and the postoperative MP of 5.1%, respectively; these thresholds of the pre- and postoperative MP may serve as a guideline in the indication for a concomitant pelvic osteotomy. Our results also indicate that the severely subluxated or dislocated hip, as well as the hip in which the femoral head is successfully reduced by VDRO but is still contained within the dysplastic acetabulum, may benefit from concomitant pelvic osteotomy.
Progress of The Journal of Functional Morphology and Kinesiology in 2019
Authors: Musumeci Giuseppe
Published: January 2020

The Journal of Functional Morphology and Kinesiology (JFMK, ISSN: 2411-5142), which was firstly released in March 2016 [...]
Experimental and Numerical Study of Pre-Swirl Stators PSS
Authors: Koushan Kourosh , Krasilnikov Vladimir , Nataletti Marco , Sileo Lucia , Spence Silas
Published: January 2020

Energy saving within shipping is gaining more attention due to environmental awareness, financial incentives, and, most importantly, new regional and international rules, which limit the acceptable emission from the ships considerably. One of the measures is installation of energy saving devices (ESD). One type of such a device, known as pre-swirl stator (PSS), consists of a number (usually 3 to 5) of fins, which are mounted right in front of the propeller. By modifying the inflow and swirl into the propeller, the fins of a PSS have the possibility to increase the total propulsion efficiency. However, at the same time, they may introduce additional resistance either due to changes in pressure distribution over the aft ship or due to its own resistance of fins. In this paper, the authors present experimental and numerical investigation of a PSS for a chemical tanker. Numerical analysis of the vessel with and without PSS is performed in the model and full scale. Model testing is performed with and without PSS to verify the power savings predicted numerically. Among other quantities, 3D wake field behind the hull is densely measured at different planes, starting from the PSS plane to the rudder stock plane. 3D wake measurements are also conducted with a running propeller. The measurements show considerable improvement in the performance of the vessel fitted with PSS. On the numerical side, analyses show that scale effect plays an important role in the ESD performance. Investigation of the scale effect on the vessel equipped with an ESD provides new insight for the community, which is investing more into the development of energy saving devices, and it offers valuable information for the elaboration of scaling procedures for such vessels.
Contextualizing Landscape-Scale Forest Cover Loss in the Democratic Republic of Congo (DRC) between 2000 and 2015
Authors: Molinario Giuseppe , Hansen Matthew , Potapov Peter , Tyukavina Alexandra , Stehman Stephen
Published: January 2020

Shifting cultivation has been shown to be the primary cause of land use change in the Democratic Republic of Congo (DRC). Traditionally, forested and fallow land are rotated in a slash and burn cycle that has created an agricultural mosaic, including secondary forest, known as the rural complex. This study investigates the land use context of new forest clearing (during 2000–2015) in primary forest areas outside of the established rural complex. These new forest clearings occur as either rural complex expansion (RCE) or isolated forest perforations (IFP), with consequent implications on the forest ecosystem and biodiversity habitat. During 2000–2015, subsistence agriculture was the dominant driver of forest clearing for both extension of settled areas and pioneer clearings removed from settled areas. Less than 1% of clearing was directly attributable to land uses such as mining, plantations, and logging, showing that the impact of commercial operations in the DRC is currently dwarfed by a reliance on small-holder shifting cultivation. However, analyzing the landscape context showed that large-scale agroindustry and resource extraction activities lead to increased forest loss and degradation beyond their previously-understood footprints. The worker populations drawn to these areas create communities that rely on shifting cultivation and non-timber forest products (NTFP) for food, energy, and building materials. An estimated 12% of forest loss within the RCE and 9% of the area of IFP was found to be within 5 km of mines, logging, or plantations. Given increasing demographic and commercial pressures on DRC’s forests, it will be crucial to factor in this landscape-level land use change dynamic in land use planning and sustainability-focused governance.
The Moderate Operation Scales of Apples Based on Output, Profit, and Unit Production Costs in the Shaanxi Province of China
Authors: Zhang Congying , Chang Qian , Shao Liqun , Huo Xuexi
Published: January 2020

In the Shaanxi province, small and scattered plots impede an increase in the efficiency of apple production. Developing a moderate operation scale is a proper tool to solve inefficiencies in apple production, as it enables improving the factor allocation efficiency, resulting in higher yields, higher profit, or lower production costs. However, the moderate operation scales, based on output, profit, and production costs, may be different. This paper aimed to evaluate the moderate operation scale of apples from three perspectives of increasing yields and profits and reducing unit production cost. The study was based on survey data collected from 661 randomly selected apple farmers in eight counties of the Shaanxi province, China. The collected data were analyzed quantitatively by the input-output model, the net profit model, and unit production cost model. The findings show that: (1) The moderate operation scale oriented to increasing apple yields in the Shaanxi province should be 0.87–1.53 ha. (2) The moderate operation scale oriented to increasing the net profit of farmers in the Shaanxi province should be over 1.53 ha. (3) The moderate operation scale oriented to reducing the unit cost of apple production in the Shaanxi province should be 0.20–0.53 ha. The study provides evidence that policymakers should grasp the balance point and find the intersection of the operation scale based on output, profit, and unit production cost when guiding apple growers to carry out the moderate scale. We propose that 0.87–1.53 ha may be a suitable operation scale for apple production in the Shaanxi province at the current stage.
Acknowledgement to Reviewers of Land in 2019
Authors:   Land Editorial Office
Published: January 2020

The editorial team greatly appreciates the reviewers who have dedicated their considerable time and expertise to the journal’s rigorous editorial process over the past 12 months, regardless of whether the papers are finally published or not.[...]
Mapping Land Cover Change over a 25-Year Period (1993–2018) in Sri Lanka Using Landsat Time-Series
Authors: Rathnayake Chithrangani WM , Jones Simon , Soto-Berelov Mariela
Published: January 2020

Land use and land cover change (LULCC) are dynamic over time and space due to human and biophysical factors. Accurate and up-to-date LULCC information is a mandatory part of environmental change analysis and natural resource management. In Sri Lanka, there is a significant temporal gap in the existing LULCC information due to the civil war that took place from 1983 to 2009. In order to fill this gap, this study presents a whole-country LULCC map for Sri Lanka over a 25-year period using Landsat time-series imagery from 1993 to 2018. The LandTrendr change detection algorithm, utilising the normalised burn ratio (NBR) and normalised difference vegetation index (NDVI), was used to develop spectral trajectories over this time period. A land cover change and disturbance map was created with random forest, using 2117 manually interpreted reference pixels, of which 75% were used for training and 25% for validation. The model achieved an overall accuracy of 94.14%. The study found that 890,003.52 hectares (ha) (13.5%) of the land has changed, while 72,266.31 ha (1%) was disturbed (but not permanently changed) over the last 25 years. LULCC was found to concentrate on two distinct periods (2000 to 2004 and 2010 to 2018) when social and economic stability allowed greater land clearing and investment opportunities. In addition, LULCC was found to impact forest reserves and protected areas. This new set of Sri Lanka-wide land cover information describing change and disturbance may provide a reference point for policy makers and other stakeholders to aid in decision making and for planning purposes.
The Performance of SiO2 and TiO2 Nanoparticles as Lubricant Additives in Sunflower Oil
Authors: Cortes Vicente , Sanchez Karen , Gonzalez Ramiro , Alcoutlabi Mataz , Ortega Javier A.
Published: January 2020

In recent years, there has been growing concern regarding the use of petroleum-based lubricants. This concern has generated interest in readily biodegradable fluids such as vegetable oils. The present work evaluated the rheological and tribological characteristics of sunflower oil modified with silicon dioxide (SiO2) and titanium dioxide (TiO2) nanoparticles as lubricant additives at different concentrations. A parallel plate rheometer was used to evaluate the effects of concentration and shear rate on the shear viscosity, and the experimental data was compared with conventional models. The wear protection and friction characteristics of the oil-formulations were evaluated by conducting block-on-ring sliding tests. Surface analysis-based instruments, including scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and profilometry, were used to characterize the morphology and structure of the worn surfaces. The experimental results showed that the coefficient of friction decreased with the addition of SiO2 and TiO2 nanoparticles by 77.7% and 93.7%, respectively when compared to base sunflower oil. Furthermore, the volume loss was lowered by 74.1% and 70.1%, with the addition of SiO2 and TiO2 nanoparticles, respectively. Based on the experimental results, the authors conclude that modified sunflower oil enhanced with nanoparticles has the potential for use as a good biodegradable lubricant.
Macroscopic Friction Studies of Alkylglucopyranosides as Additives for Water-Based Lubricants
Authors: Chen Wei , Amann Tobias , Kailer Andreas , Rühe Jürgen
Published: January 2020

Water-based lubricants might become an interesting alternative to conventional oil-based lubricants and help to reduce wear as well as improve the energy efficiency of transport processes. Since pure water is generally a rather poor lubricant due to its low viscosity and corrosiveness, it must be tribologically optimized with suitable additives. Here, we study the friction behavior of alkyl glucopyranosides (AGPs) with varying lengths of the alkyl chain. Sliding experiments show that a significant reduction in the coefficient of friction compared to that of pure water is observed. The extent of friction reduction depends strongly on the concentration and on the shearing conditions. It is assumed that the low coefficients of friction are due to the ability of AGPs to form liquid crystalline phases with an ordered structure in the friction gap. Furthermore, the interaction of the AGPs with the surface forms a wear protection layer (boundary lubrication). The friction properties of the water-based system are compared to those of a conventional, mineral oil-based lubricant.
Synthesis and Characterization of Complex Nanostructured Thin Films Based on Titanium for Industrial Applications
Authors: Vladoiu Rodica , Mandes Aurelia , Dinca Virginia , Balasoiu Maria , Soloviov Dmytro , Turchenko Vitalii
Published: January 2020

Titanium-based composites—titanium and silver (TiAg) and titanium and carbon (TiC)—were synthesized by the Thermionic Vacuum Arc (TVA) method on substrates especially for gear wheels and camshaft coating as mechanical components of irrigation pumps. The films were characterized by surface morphology, microstructure, and roughness through X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Small-Angle Neutron Scattering (SANS). The silver (Ag) films crystallized into a cubic system with lattice a = 4.0833 Å at room temperature, indexed as cubic Ag group Fm3m. The crystallites were oriented in the [111] direction, and mean grain size was 111 = 265 Å. The TiC structure revealed a predominant cubic TiC phase, with a = 0.4098 as a lattice parameter determined by Cohen’s method. Average roughness (Ra) was 8 nm for the as-grown 170 nm thick TiAg film, and 1.8 nm for the as-grown 120 nm thick TiC film. Characteristic SANS contribution was detected from the TiAg layer deposited on a substrate of high-quality stainless steel with 0.45% carbon (OLC45) in the range of 0.015 Å−1 ≤ Q ≤ 0.4 Å−1, revealing the presence of sharp surfaces and an averaged triaxial ellipsoidal core-shell object.
Effect of Flash Light Sintering on Silver Nanowire Electrode Networks
Authors: Yang Dae-Jin , Kim Seyun , Sohn Hiesang , Moon Kyoung-Seok , Sim Woo Hyeong , Jeong Hyung Mo , Shin Weon Ho
Published: January 2020

We investigated the flash light sintering process to effectively reduce electrical resistance in silver nanowire networks. The optimum condition of the flash light sintering process reduces the electrical resistance by ~20%, while the effect of the conventional thermal annealing processes is rather limited for silver nanowire networks. After flash light sintering, the morphology of the junction between the silver nanowires changes to a mixed-phase structure of the two individual nanowires. This facile and fast process for silver nanowire welding could be highly advantageous to the mass production of silver nanowire networks.
A Process Optimization and Performance Study of Environmentally Friendly Waste Newspaper/Polypropylene Film Layered Composites
Authors: Guan Neng , Hu Chuanshuang , Guan Litao , Zhang Weiwei , Yun Hong , Hu Xiaojing
Published: January 2020

Waste newspaper are currently used in a single way and have low utilization rates. In this paper, the optimal process of preparing environmentally friendly layered composites by using waste newspaper combined with polypropylene film lamination was studied. The effects of hot-pressing temperature, hot-pressing time and paper content on the properties of the composites were analyzed. The results showed that under the process conditions of hot-pressing temperature 180 °C, compression time 20 min and paper content 66.7%, the obtained composite material had a flexural strength of 126 MPa, a tensile strength of 95 MPa, an impact strength of 5.3 kJ/m2 and a water absorption thickness expansion ratio of 3.2%. Tensile performance increased by 164% compared to the original waste newspaper. Compared to our previous work, the hot processing time had been cut in half and costs were lower. In terms of creep properties, the unrecoverable strain rate was reduced by 57.5% compared to pure polypropylene. The results show that the material can maintain excellent flexural strength, tensile strength and water absorption performance while making good use of waste newspaper.
Aluminum Inserts for Enhancing Heat Transfer in PCM Accumulator
Authors: Dmitruk Anna , Naplocha Krzysztof , Grzęda Jakub , Kaczmar Jacek W.
Published: January 2020

Phase change materials (PCMs) are applied in heat storage units, as they are able to accumulate the energy in the form of the latent heat of fusion. Thus, they can be used in recovering the excess of heat from various industrial processes. Their main weakness is their low thermal conductivity coefficient, which strongly limits their usage. In this paper, the benefits of the application of metallic inserts in heat storage PCM-based units were elaborated. Two kinds of Al–Si spatial elements (foams and honeycomb structures) were produced with the use of means of the investment casting method. Key factors influencing the technological process were established. The surface’s roughness was measured in order to compare the obtained structures with their patterns in terms of the casting’s accuracy. The compressive strength of the samples was tested, and their fatigue resistance was considered. The thermal performance of manufactured inserts in the PCM (paraffin)-based accumulator, supported by the calculation of heat fluxes, was analyzed and adjusted. Finally, further optimization was conducted in terms of the volume ratio of the metal insert to the PCM. Metallic inserts were found to significantly affect the performance of the entire energy storage system, as their use results in reduced charging time, a longer heat release time, increased maximum temperature, and a significant reduction in the temperature gradient in the heat storage unit.
Technology of Polymer Microtips’ Manufacturing on the Ends of Multi-Mode Optical Fibers
Authors: Żuchowska (Chruściel) Monika , Marć Paweł , Jakubowska Iwona , Jaroszewicz Leszek R.
Published: January 2020

The technology of polymer microtips’ manufacturing on the ends of selected multi-mode fibers has been reported. The study’s key element was an extended description of technology parameters’ influence on the shape of these 3D microstructures. Basic technology parameters such as spectral characteristics of the light source, monomer mixture type, optical power, and exposure time were taken under consideration. Depending on those parameters, different shapes, sizes, and surface structures of microtips were obtained. The spectral characteristics of the light and optical power delivered to a monomer drop were identified as the most important parameters for the formation of the desired 3D shape of the microtip. Presented experimental results are the base for further studies directed to the application of these micro-elements in the fields of optical measurements and sensors’ technology.
Solution Processable CrN Thin Films: Thickness-Dependent Electrical Transport Properties
Authors: Hui Zhenzhen , Zuo Xuzhong , Ye Longqiang , Wang Xuchun , Zhu Xuebin
Published: January 2020

Thickness is a very important parameter with which to control the microstructures, along with physical properties in transition-metal nitride thin films. In work presented here, CrN films with different thicknesses (from 26 to 130 nm) were grown by chemical solution deposition. The films are pure phase and polycrystalline. Thickness dependence of microstructures and electrical transport behavior were studied. With the increase of films thickness, grain size and nitrogen content are increased, while resistivity, zero-field sensitivity and magnetoresistance are decreased. In the temperature range of 5–350 K, all samples exhibited semiconductor-like properties with dρ/dT < 0. For the range above and below the Néel temperature, the resistivity can be fitted by the thermal activation model and the two-dimensional weak localization (2D-WL) model, respectively. The ultra-low magnetoresistance at a low temperature under high magnetic fields with a large zero-field sensitivity was observed in the CrN thin films. The zero-field sensitivity can be effectively tuned to 10−2 K−1 at 5 K with a magnetoresistance of less than 1% at 2 K under 14 T by reasonably controlling the thickness.
Areal Surface Roughness Optimization of Maraging Steel Parts Produced by Hybrid Additive Manufacturing
Authors: Wüst Philipp , Edelmann André , Hellmann Ralf
Published: January 2020

We report on an experimental study and statistical optimization of the surface roughness using design of experiments and the Taguchi method for parts made of 1.2709 maraging steel. We employ a hybrid additive manufacturing approach that combines additive manufacturing by selective laser melting with subtractive manufacturing using milling in an automated process within a single machine. Input parameters such as laser power, scan speed, and hatching distance have been varied in order to improve surface quality of unmachined surfaces. Cutting speed, feed per tooth, and radial depth of cut have been varied to optimize surface roughness of the milled surfaces. The surfaces of the samples were characterized using 3D profilometry. Scan speed was determined as the most important parameter for non-machined surfaces; radial depth of cut was found to be the most significant parameter for milled surfaces. Areal surface roughness S a could be reduced by up to 40% for unmachined samples and by 23% for milled samples as compared to the prior state of the art.
Analysis of Fatigue and Healing Properties of Conventional Bitumen and Bio-Binder for Road Pavements
Authors: Gaudenzi Elena , Cardone Fabrizio , Lu Xiaohu , Canestrari Francesco
Published: January 2020

The analysis of fatigue behavior of bituminous binders is a complex issue due to several time-temperature dependent phenomena which interact simultaneously, such as damage accumulation, viscoelasticity, thixotropy, and healing. The present research involves rheological measurements aimed at evaluating the fatigue behavior and compares the self-healing capability of two plain bitumen and a bio-binder obtained by partially replacing one of the plain bitumen with a renewable bio-oil. Healing potential was assessed by means of an experimental approach previously implemented for modified bitumen and bituminous mastic and based on the use of a dynamic shear rheometer (DSR). The effects of some variables such as bitumen type, bio-oil addition, and aging on the healing potential of binders were taken into account. Results showed that the above-mentioned method for healing analysis is also suitable for conventional and bio-add binders. Outcomes of the experimental investigation highlight that fatigue and self-healing are mainly dependent on binder consistency and also affected by aging. Finally, the addition of bio-oil may induce even better performances in terms of healing potential compared to conventional bitumen, especially in aged condition.
Simulation of Thermal Behavior of Glass Fiber/Phenolic Composites Exposed to Heat Flux on One Side
Authors: Li Han , Wang Nasidan , Han Xuefei , Fan Baoxin , Feng Zhenyu , Guo Shijun
Published: January 2020

A 3D thermal response model is developed to evaluate the thermal behavior of glass fiber/phenolic composite exposed to heat flux on one side. The model is built upon heat transfer and energy conservation equations in which the heat transfer is in the form of anisotropic heat conduction, absorption by matrix decomposition, and diffusion of gas. Arrhenius equation is used to characterize the pyrolysis reaction of the materials. The diffusion equation for the decomposition gas is included for mass conservation. The temperature, density, decomposition degree, and rate are extracted to analyze the process of material decomposition, which is implemented by using the UMATHT (User subroutine to define a material’s thermal behavior) and USDFLD (User subroutine to redefine field variables) subroutines via ABAQUS code. By comparing the analysis results with experimental data, it is found that the model is valid to simulate the evolution of a glass fiber/phenolic composite exposed to heat flux from one side. The comparison also shows that longer time is taken to complete the pyrolysis reaction with increasing depth for materials from the numerical simulation, and the char region and the pyrolysis reaction region enlarge further with increasing time. Furthermore, the decomposition degree and temperature are correlated with depths, as well as the peak value of decomposition rate and the time to reach the peak value.
Comparative Screening of the Structural and Thermomechanical Properties of FDM Filaments Comprising Thermoplastics Loaded with Cellulose, Carbon and Glass Fibers
Authors: Karakoç Alp , Rastogi Vibhore K. , Isoaho Tapani , Tardy Blaise , Paltakari Jouni , Rojas Orlando J.
Published: January 2020

Additive manufacturing (AM) has been rapidly growing for a decade in both consumer and industrial products. Fused deposition modeling (FDM), one of the most widely used additive manufacturing methods, owes its popularity to cost effectiveness in material and equipment investment. Current efforts are aimed toward high load-bearing capacity at low material costs. However, the mechanical reliability of end-products derived from these compositions and their dependence on microstructural effects, have remained as major limitations. This is mainly owing to the unknown mechanics of the materials, including the reinforcing or filler components and their interphase/interface compatibility. For this reason, here we investigate the most relevant commercial polymeric materials used in composite filaments, associated phases and the characterization protocols that can guide component selection, screening and troubleshooting. We first present thermal analyses (thermogravimetric, TGA and differential scanning calorimetry, DSC) in relation to the constituent fractions and identify the type of polymer for uses in filaments production. The influence of various fillers is unveiled in terms of the crystallization behavior of derived 3D-printed parts. To understand the microstructural effects on the material strength, we carry out a series of tensile experiments on 3-D printed dog-bone shaped specimens following ISO standards. Simultaneously, real-time thermal energy dissipation and damage analyses are applied by using infrared measurements at fast frame rates (200 Hz) and high thermal resolution (50 mK). The failure regions of each specimen are examined via optical, scanning and transmission electron microscopies. The results are used to reveal new insights into the size, morphology and distribution of the constituents and interphases of polymer filaments for FDM. The present study represents advancement in the field of composite filament fabrication, with potential impact in the market of additive manufacturing.
The Improvement of Moisture Resistance and Organic Compatibility of SrAl2O4: Eu2+, Dy3+ Persistent Phosphors Coated with Silica–Polymer Hybrid Shell
Authors: Lyu Lei , Chen Yuxian , Yu Liting , Li Rui , Zhang Liu , Pei Jianzhong
Published: January 2020

The existing road surface marking with poor visibility at night results in traffic safety hazards in insufficient lighting roads. This study aims to prepare the dedicated aluminate-based persistent phosphors considering the integrated pavement environment, as the first step to achieve the durable luminescent road surface marking. SrAl2O4: Eu2+, Dy3+ persistent phosphors coated with silica–polymer hybrid shell were prepared by chemical precipitation and sol-gel method to improve moisture resistance and organic compatibility. The optimum silane coupling agent type and dosage, the surfactant dosage, the optimum sodium silicate dosage, and the coating reaction time in silica shell and polymer shell coating were studied based on the moisture resistance test. The silica–polymer hybrid shell coating balances the organic compatibility and thermal stability as compared to the silica or polymer shell coating in the oil absorption test and thermogravimetric analysis. Ex-Em Spectra, XRD, and SEM method were used to characterize the persistent phosphors, indicating the preparation does not destroy the persistent phosphors. The outstanding durable properties of SrAl2O4: Eu2+, Dy3+ persistent phosphors coated with silica–polymer hybrid shell as shown in this research is crucial for its potential application in waterborne luminescent coatings of road surface marking.
Development of the Measuring Techniques for Estimating the Air Void System Parameters in Concrete Using 2D Analysis Method
Authors: Molendowska Agnieszka , Wawrzeńczyk Jerzy , Kowalczyk Henryk
Published: January 2020

The purpose of the present study was to determine the impact of image quality on the results of air void system parameters determination in air-entrained concretes. The focus was on technical aspects related to the preparation of the scanned image of the concrete surface, which was then subjected to 2D surface analysis. Image processing aimed at separating joined voids and removing various types of defects in aggregate and cement mortar. The specific surface of the voids was determined with the air void equivalent diameter or perimeter as the calculation basis. Applying the Schwartz–Saltykov method, the 3D distribution of the air voids was reconstructed based on 2D measurements. On this basis, the micro-air content A300 was determined. The results of the 2D method were compared with the results of determinations carried out using the linear traverse (1D) method according to EN 480-11. The tests confirm the need to correct the image prior to measurements. Comparative tests showed good agreement between the air void system parameters determined using the 2D analysis and the EN 480-11 chord length counting method.
Acoustic Emission and Numerical Analysis of Pine Beams Retrofitted with FRP and Poplar Wood
Authors: Rescalvo Francisco J. , Rodríguez María , Bravo Rafael , Abarkane Chihab , Gallego Antolino
Published: January 2020

Acoustic emission (AE) released by pine beams retrofitted with fiber reinforced plastic (FRP) and poplar planks in bending is analyzed. Basalt fabric (FB), carbon fabric (FC), and carbon pultruded laminate (LC) have been used as FRP. Experimental results and AE behavior are discussed based on an elastoplastic finite-element numerical model. The model demonstrates a strong strain concentration at the end of poplar planks, which causes high AE activity in these areas and acts as a precursor of the delamination of the poplar plank. Based on the experimental results, some AE criteria for predicting the onset of the delamination are tentatively proposed.
Abrasive Wear Behavior of Cryogenically Treated Boron Steel (30MnCrB4) Used for Rotavator Blades
Authors: Singh Tejinder Pal , Singla Anil Kumar , Singh Jagtar , Singh Kulwant , Gupta Munish Kumar , Ji Hansong , Song Qinghua , Liu Zhanqiang , Pruncu Catalin I.
Published: January 2020

Rotavator blades are prone to significant wear because of the abrasive nature of sand particles. The aim of this research work is to investigate the effect of cryogenic treatment and post tempering on abrasive wear behavior, in the presence of angular quartz sand (grain size of 212–425 μm), of rotavator blade material of boron steel (30MnCrB4). Cryogenic treatment has caused an improvement in the abrasive wear resistance and microhardness of 30MnCrB4 by 60% and 260.73%, respectively, compared to untreated material due to enhancement in hardness, the conversion of retained austenite into martensite, and the precipitation of secondary carbides in boron steel after exposure to cryogenic temperature. Economic analysis justifies the additional cost of cryogenic treatment.
A New Environmentally-Friendly System for Extracting Cellulose from Corn Straw: The Low Temperature Laccase System
Authors: Song Heming , Jia Hongge , Wang Qingji , Zhao Xinyi , Yang Guoxing , Zhang Mingyu , Zhou Hailiang , Xu Shuangping , Zang Yu , Wang Yazhen , Ma Liqun
Published: January 2020

Corn straw is an agricultural waste. The system for extracting cellulose from corn straw at a high temperature has been widely reported by researchers. However, the system for extracting cellulose from corn straw at a low temperature has been rarely reported. In this paper, a new system for extracting cellulose from corn straw at a low temperature was reported for the first time. This new system is designated as the low temperature laccase system (LTLS). Cellulose was successfully extracted from corn straw by the LTLS, and the used solution could be recycled. Therefore, the low temperature laccase system is an environmentally-friendly system. The cellulose content in corn straw is 30–40%. The yield of cellulose extracted by LTLS was 33%. The obtained cellulose product was creamy white. The extracted cellulose samples were characterized by using infrared spectroscopy (IR), thermogravimetry (TG), and X-ray diffraction (XRD). The results were consistent with that of standard cellulose. We confirmed that the LTLS extracted cellulose from corn straw with high purity.
Model-Based Residual Stress Design in Multiphase Seamless Steel Tubes
Authors: Leitner Silvia , Winter Gerald , Klarner Jürgen , Antretter Thomas , Ecker Werner
Published: January 2020

Residual stresses in quenched seamless steel tubes highly depend on the cooling conditions to which the tubes have been subjected. The design aspect of how to use controlled cooling strategies in multiphase steel tubes to achieve certain residual stress and phase configurations is discussed. In an experimentally validated finite element (FE) model considering a coupled evolution of martensite and bainite, three cooling strategies are tested for a low-alloyed 0.25 wt.% C steel tube. The strategies are (i) external cooling only, (ii) internal and external cooling for low residual stresses in a mainly martensitic tube, and (iii) internal and external cooling with low cooling rate for a mainly bainitic tube. The strategies represent design cases, where low residual stresses with different phase compositions are provoked, in order to show the potential of numerical analysis for residual stress and property design. It can be concluded that, for the investigated steel class, intense external cooling leads to a characteristic residual stress profile regardless of the dimension. A combination of external and internal cooling allows a more flexible design of residual stress and phase distribution by choosing different cooling parameters (i.e., water amount and cooling times). In general, lower cooling rates lead to lower thermal misfit strains, and thus less plasticity and lower residual stresses.
Evaluation of Strength Development in Concrete with Ground Granulated Blast Furnace Slag Using Apparent Activation Energy
Authors: Yang Hyun-Min , Kwon Seung-Jun , Myung Nosang Vincent , Singh Jitendra Kumar , Lee Han-Seung , Mandal Soumen
Published: January 2020

Ground granulated blast furnace slag (GGBFS) conventionally has been incorporated with ordinary Portland cement (OPC) owing to reduce the environmental load and enhance the engineering performance. Concrete with GGBFS shows different strength development of normal concrete, but sensitive, to exterior condition. Thus, a precise strength evaluation technique based on a quantitative model like full maturity model is required. Many studies have been performed on strength development of the concrete using equivalent age which is based on the apparent activation energy. In this process, it considers the effect of time and temperature simultaneously. However, the previous models on the apparent activation energy of concrete with mineral admixtures have limitation, and they have not considered the effect of temperature on strength development. In this paper, the apparent activation energy with GGBFS replacement ratio was calculated through several experiments and used to predict the compressive strength of GGBFS concrete. Concrete and mortar specimens with 0.6 water/binder ratio, and 0 to 60% GGBFS replacement were prepared. The apparent activation energy (Ea) was experimentally derived considering three different curing temperatures. Thermodynamic reactivity of GGBFS mixed concrete at different curing temperature was applied to evaluate the compressive strength model, and the experimental results were in good agreement with the model. The results show that when GGBFS replacement ratio was increased, there was a delay in compressive strength.