bluuebunny/crossref_metadata_2025 huggingface dataset:
Advances in Zika Virus–Host Cell Interaction: Current Knowledge and Future Perspectives
Authors: Lee Jae Kyung , Shin Ok Sarah
Published: March 2019

Emerging mosquito-transmitted RNA viruses, such as Zika virus (ZIKV) and Chikungunya represent human pathogens of an immense global health problem. In particular, ZIKV has emerged explosively since 2007 to cause a series of epidemics in the South Pacific and most recently in the Americas. Although typical ZIKV infections are asymptomatic, ZIKV infection during pregnancy is increasingly associated with microcephaly and other fetal developmental abnormalities. In the last few years, genomic and molecular investigations have established a remarkable progress on the pathogenic mechanisms of ZIKV infection using in vitro and in vivo models. Here, we highlight recent advances in ZIKV-host cell interaction studies, including cellular targets of ZIKV, ZIKV-mediated cell death mechanisms, host cell restriction factors that limit ZIKV replication, and immune evasion mechanisms utilized by ZIKV. Understanding of the mechanisms of ZIKV–host interaction at the cellular level will contribute crucial insights into the development of ZIKV therapeutics and vaccines.
Using Malone’s Theoretical Model on Gamification for Designing Educational Rubrics
Authors: Corona Martínez Daniel , Real García José Julio
Published: March 2019

How could a structured proposal for an evaluation rubric benefit from assessing and including the organizational variables used when one of the first definitions of gamification related to game theory was established by Thomas W. Malone in 1980? By studying the importance and current validity of Malone’s corollaries on his article What makes things fun to Learn? this work covers all different characteristics of the concepts once used to define the term “gamification.” Based on the results of this analysis, we will propose different evaluation concepts that will be assessed and included in a qualitative proposal for an evaluation rubric, with the ultimate goal of including a holistic approach to all different aspects related to evaluation for active methodologies in a secondary education environment.
Ferritin: A Platform for MRI Contrast Agents Delivery
Authors: Ruggiero Maria Rosaria , Alberti Diego , Bitonto Valeria , Geninatti Crich Simonetta
Published: March 2019

The search for high relaxivities and increased specificity continues to be central to the development of paramagnetic contrast agents for magnetic resonance imaging (MRI). Ferritin, due to its unique surface properties, architecture, and biocompatibility, has emerged as a natural nanocage that can potentially help to reach both these goals. This review aims to highlight recent advances in the use of ferritin as a nanoplatform for the delivery of metal-based MRI contrast agents (containing Gd3+, Mn2+, or Fe2O3) alone or in combination with active molecules used for therapeutic purposes. The collected results unequivocally show that the use of ferritin for contrast agent delivery leads to more accurate imaging of cancer cells and a significantly improved targeted therapy.
Multi-Scenario Species Distribution Modeling
Authors: Senay Senait D. , Worner Susan P.
Published: March 2019

Correlative species distribution models (SDMs) are increasingly being used to predict suitable insect habitats. There is also much criticism of prediction discrepancies among different SDMs for the same species and the lack of effective communication about SDM prediction uncertainty. In this paper, we undertook a factorial study to investigate the effects of various modeling components (species-training-datasets, predictor variables, dimension-reduction methods, and model types) on the accuracy of SDM predictions, with the aim of identifying sources of discrepancy and uncertainty. We found that model type was the major factor causing variation in species-distribution predictions among the various modeling components tested. We also found that different combinations of modeling components could significantly increase or decrease the performance of a model. This result indicated the importance of keeping modeling components constant for comparing a given SDM result. With all modeling components, constant, machine-learning models seem to outperform other model types. We also found that, on average, the Hierarchical Non-Linear Principal Components Analysis dimension-reduction method improved model performance more than other methods tested. We also found that the widely used confusion-matrix-based model-performance indices such as the area under the receiving operating characteristic curve (AUC), sensitivity, and Kappa do not necessarily help select the best model from a set of models if variation in performance is not large. To conclude, model result discrepancies do not necessarily suggest lack of robustness in correlative modeling as they can also occur due to inappropriate selection of modeling components. In addition, more research on model performance evaluation is required for developing robust and sensitive model evaluation methods. Undertaking multi-scenario species-distribution modeling, where possible, is likely to mitigate errors arising from inappropriate modeling components selection, and provide end users with better information on the resulting model prediction uncertainty.
The 2016 US Presidential Elections: What Went Wrong in Pre-Election Polls? Demographics Help to Explain
Authors: Zeedan Rami
Published: March 2019

This study examined the accuracy of the various forecasting methods of the 2016 US Presidential Elections. The findings revealed a high accuracy in predicting the popular vote. However, this is most suitable in an electoral system which is not divided into constituencies. Instead, due to the Electoral College method used in the US elections, forecasting should focus on predicting the winner in every state separately. Nevertheless, miss-predicted results in only a few states led to false forecasting of the elected president in 2016. The current methods proved less accurate in predicting the vote in states that are less urbanized and with less diverse society regarding race, ethnicity, and religion. The most challenging was predicting the vote of people who are White, Protestant Christians, and highly religious. In order to improve pre-election polls, this study suggests a few changes to the current methods, mainly to adopt the “Cleavage Sampling” method that can better predict the expected turnout of specific social groups, thus leading to higher accuracy of pre-election polling.
Who Are Dispensed the Bulk Amount of Prescription Opioids?
Authors: Islam M. Mofizul , Wollersheim Dennis
Published: March 2019

Background: Excessive and non-medical use of prescription opioids is a public health crisis in many settings. This study examined the distribution of user types based on duration of use, trends in and associated factors of dispensing of prescription opioids in New South Wales and Victoria, Australia. Methods: 10% sample of unit-record data of four-year dispensing of prescription opioids was analysed. Quantities dispensed were computed in defined daily dose (DDD). Multilevel models examined factors associated with the duration of dispensing and the quantity dispensed in local government areas. Results: Overall, 53% were single-quarter, 37.3% medium-episodic (dispensed 2–6 quarters), 5% long-episodic (dispensed 7–11 quarters) and 5% were chronic users (dispensed 12–14 quarters). More than 80% of opioids in terms of DDD/1000 people/day were dispensed to long-episodic and chronic users. Codeine and oxycodone were most popular items—both in terms of number of users and quantity dispensed. Duration of dispensing was significantly higher for women than men. Dispensing quantity and duration increased with increasing age and residence in relatively poor neighborhoods. Conclusions: Although only 5% were chronic users, almost 60% of opioids (in DDD/1000 people/day) were dispensed to them. Given that chronic use is linked to adverse health outcomes, and there is a progression toward chronic use, tailored interventions are required for each type of users.
Comparative Gene Expression Profiles in Parathyroid Adenoma and Normal Parathyroid Tissue
Authors: Chai Young , Chae Heejoon , Kim Kwangsoo , Lee Heonyi , Choi Seongmin , Lee Kyu , Kim Sang
Published: March 2019

Parathyroid adenoma is the main cause of primary hyperparathyroidism, which is characterized by enlarged parathyroid glands and excessive parathyroid hormone secretion. Here, we performed transcriptome analysis, comparing parathyroid adenomas with normal parathyroid gland tissue. RNA extracted from ten parathyroid adenoma and five normal parathyroid samples was sequenced, and differentially expressed genes (DEGs) were identified using strict cut-off criteria. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed using DEGs as the input, and protein-protein interaction (PPI) networks were constructed using Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) and visualized in Cytoscape. Among DEGs identified in parathyroid adenomas (n = 247; 45 up-regulated, 202 down-regulated), the top five GO terms for up-regulated genes were nucleoplasm, nucleus, transcription DNA-template, regulation of mRNA processing, and nucleic acid binding, while those for down-regulated genes were extracellular exosome, membrane endoplasmic reticulum (ER), membrane, ER, and melanosome. KEGG enrichment analysis revealed significant enrichment of five pathways: protein processing in ER, protein export, RNA transport, glycosylphosphatidylinositol-anchor biosynthesis, and pyrimidine metabolism. Further, PPI network analysis identified a densely connected sub-module, comprising eight hub molecules: SPCS2, RPL23, RPL26, RPN1, SEC11C, SEC11A, RPS25, and SEC61G. These findings may be helpful in further analysis of the mechanisms underlying parathyroid adenoma development.
Epicardial Adipose Tissue and Renal Disease
Authors: Aeddula Narothama Reddy , Cheungpasitporn Wisit , Thongprayoon Charat , Pathireddy Samata
Published: March 2019

Epicardial adipose tissue (EAT) is derived from splanchnic mesoderm, localized anatomically between the myocardium and pericardial visceral layer, and surrounds the coronary arteries. Being a metabolically active organ, EAT secretes numerous cytokines, which moderate cardiovascular morphology and function. Through its paracrine and vasocrine secretions, EAT may play a prominent role in modulating cardiac function. EAT protects the heart in normal physiological conditions by secreting a variety of adipokines with anti-atherosclerotic properties, and in contrast, secretes inflammatory molecules in pathologic conditions that may play a dynamic role in the pathogenesis of cardiovascular diseases by promoting atherosclerosis. Considerable research has been focused on comparing the anatomical and biochemical features of EAT in healthy people, and a variety of disease conditions such as cardiovascular diseases and renal diseases. The global cardiovascular morbidity and mortality in renal disease are high, and there is a paucity of concrete evidence and societal guidelines to detect early cardiovascular disease (CVD) in this group of patients. Here we performed a clinical review on the existing evidence and knowledge on EAT in patients with renal disease, to evaluate its application as a reliable, early, noninvasive biomarker and indicator for CVD, and to assess its significance in cardiovascular risk stratification.
Observations and Modelling of Shoreface Nourishment Behaviour
Authors: Huisman Bastiaan , Walstra Dirk-Jan , Radermacher Max , de Schipper Matthieu , Ruessink B. Gerben
Published: March 2019

Shoreface nourishments are commonly applied for coastal maintenance, but their behaviour is not well understood. Bathymetric data of 19 shoreface nourishments located at alongshore uniform sections of the Dutch coast were therefore analyzed and used to validate an efficient method for predicting the erosion of shoreface nourishments. Data shows that considerable cross-shore profile change takes place at a shoreface nourishment, while an impact at the adjacent coast is hard to distinguish. The considered shoreface nourishments provide a long-term (3 to ∼30 years) cross-shore supply of sediment to the beach, but with small impact on the local shoreline shape. An efficient modelling approach is presented using a lookup table filled with computed initial erosion–sedimentation rates for a range of potential environmental conditions at a single post-construction bathymetry. Cross-shore transport contributed the majority of the losses from the initial nourishment region. This transport was driven partly by water-level setup driven currents (e.g., rip currents) and increased velocity asymmetry of the waves due to the geometrical change at the shoreface nourishment. Most erosion of the nourishment takes place during energetic wave conditions ( H m 0 ≥ 3 m) as milder waves are propagated over the nourishment without breaking. A data-model comparison shows that this approach can be used to accurately assess the erosion rates of shoreface nourishments in the first years after construction.
Genetic Testing to Guide Risk-Stratified Screens for Breast Cancer
Authors: Willoughby Ava , Andreassen Paul R. , Toland Amanda Ewart
Published: March 2019

Breast cancer screening modalities and guidelines continue to evolve and are increasingly based on risk factors, including genetic risk and a personal or family history of cancer. Here, we review genetic testing of high-penetrance hereditary breast and ovarian cancer genes, including BRCA1 and BRCA2, for the purpose of identifying high-risk individuals who would benefit from earlier screening and more sensitive methods such as magnetic resonance imaging. We also consider risk-based screening in the general population, including whether every woman should be genetically tested for high-risk genes and the potential use of polygenic risk scores. In addition to enabling early detection, the results of genetic screens of breast cancer susceptibility genes can be utilized to guide decision-making about when to elect prophylactic surgeries that reduce cancer risk and the choice of therapeutic options. Variants of uncertain significance, especially missense variants, are being identified during panel testing for hereditary breast and ovarian cancer. A finding of a variant of uncertain significance does not provide a basis for increased cancer surveillance or prophylactic procedures. Given that variant classification is often challenging, we also consider the role of multifactorial statistical analyses by large consortia and functional tests for this purpose.
How Prebiotic Chemistry and Early Life Chose Phosphate
Authors: Liu Ziwei , Rossi Jean-Christophe , Pascal Robert
Published: March 2019

The very specific thermodynamic instability and kinetic stability of phosphate esters and anhydrides impart them invaluable properties in living organisms in which highly efficient enzyme catalysts compensate for their low intrinsic reactivity. Considering their role in protein biosynthesis, these properties raise a paradox about early stages: How could these species be selected in the absence of enzymes? This review is aimed at demonstrating that considering mixed anhydrides or other species more reactive than esters and anhydrides can help in solving the paradox. The consequences of this approach for chemical evolution and early stages of life are analysed.
Dicyclohexylammonium O,O’-Diphenyl Phosphate, [(C6H11)2NH2][(C6H5O)2P(O)(O)]: Spectroscopic Study, Crystal Structure, and Hirshfeld Surface Analysis
Authors: Moghaddam Samira Nazari , Shabari Akbar Raissi , Sabbaghi Fahimeh , Pourayoubi Mehrdad , Salam Abdul Ajees Abdul
Published: March 2019

The title salt, [(C6H11)2NH2][(C6H5O)2P(O)(O)], crystallizes in the chiral space group P212121, composed of achiral cation and anion components. The strong charge-assisted N–H…O hydrogen bonds build a linear assembly along the a axis, including a non-centrosymmetric C22(6) chain graph-set motif. The intra and intermolecular C–H…O interactions as well as the C–H…π-electron ring interactions also exist in the crystal structure. Fingerprint plots are used for a detailed investigation of intermolecular interactions participating in the crystal packing. The spectroscopic features (IR, 1H NMR, 13C{1H} NMR, 31P{1H} NMR, and mass) are studied.
Implications of the Use of Silica as Active Filler in Passenger Car Tire Compounds on Their Recycling Options
Authors: van Hoek Johannes W. , Heideman Geert , Noordermeer Jacques W. M. , Dierkes Wilma K. , Blume Anke
Published: March 2019

Tires are an important vehicle component, as car handling, safety and fuel economy depend for a major part on the tire composition and construction. As a consequence, tires are improved continuously. The most prominent improvement in the recent past was the use of a silica-silane filler system in passenger car tread compounds, instead of traditionally used carbon black. For recycling and re-use of end-of-life car tire rubber one of the most promising recycling methods is devulcanization: re-plasticizing the vulcanized rubber by selectively breaking the sulfur bridges between the polymer molecules. In the present paper, the influence of silica, which is present in the passenger car tires granulate, on both devulcanization and subsequent revulcanization, is investigated. In a step-wise approach it is shown that the presence of silica influences both devulcanization and revulcanization. The best tensile strength of the revulcanizate, using a carbon-black-based revulcanization formulation, was 5 MPa. This could be improved to 6.5 MPa by using 2.8 phr of 1,3-DiPhenylGuanidine (DPG) in the revulcanization formulation. After addition of a silanization step during revulcanization by adding 3.2 phr bis[3-(TriEthoxySilyl)Propyl] Tetrasulfide (TESPT), a silane, to the formulation, the tensile strength of the revulcanizate was further improved to 8 MPa. With these results it is shown that the silica in the granulate can be used to improve the revulcanization properties. To check the benefits of using pure tire tread material for the devulcanization and subsequent revulcanization, of both a carbon black and a silica-based virgin tread compound, it is shown that a tensile strength of the revulcanizate of 13 MPa can be reached. This shows the potential of devulcanized rubber when the various tire components are separated before whole car tire material is granulated as the beginning of the recycling.
Hybrid Perovskites Depth Profiling with Variable-Size Argon Clusters and Monatomic Ions Beams
Authors: Noël Céline , Pescetelli Sara , Agresti Antonio , Franquet Alexis , Spampinato Valentina , Felten Alexandre , di Carlo Aldo , Houssiau Laurent , Busby Yan
Published: March 2019

Ion beam depth profiling is increasingly used to investigate layers and interfaces in complex multilayered devices, including solar cells. This approach is particularly challenging on hybrid perovskite layers and perovskite solar cells because of the presence of organic/inorganic interfaces requiring the fine optimization of the sputtering beam conditions. The ion beam sputtering must ensure a viable sputtering rate on hard inorganic materials while limiting the chemical (fragmentation), compositional (preferential sputtering) or topographical (roughening and intermixing) modifications on soft organic layers. In this work, model (Csx(MA0.17FA0.83)100−xPb(I0.83Br0.17)3/cTiO2/Glass) samples and full mesoscopic perovskite solar cells are profiled using low-energy (500 and 1000 eV) monatomic beams (Ar+ and Cs+) and variable-size argon clusters (Arn+, 75 < n < 4000) with energy up to 20 keV. The ion beam conditions are optimized by systematically comparing the sputtering rates and the surface modifications associated with each sputtering beam. X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, and in-situ scanning probe microscopy are combined to characterize the interfaces and evidence sputtering-related artifacts. Within monatomic beams, 500 eV Cs+ results in the most intense and stable ToF-SIMS molecular profiles, almost material-independent sputtering rates and sharp interfaces. Large argon clusters (n > 500) with insufficient energy (E < 10 keV) result in the preferential sputtering of organic molecules and are highly ineffective to sputter small metal clusters (Pb and Au), which tend to artificially accumulate during the depth profile. This is not the case for the optimized cluster ions having a few hundred argon atoms (300 < n < 500) and an energy-per-atom value of at least 20 eV. In these conditions, we obtain (i) the low fragmentation of organic molecules, (ii) convenient erosion rates on soft and hard layers (but still different), and (iii) constant molecular profiles in the perovskite layer, i.e., no accumulation of damages.
Conductomeric Evaluation of the Release Kinetics of Active Substances from Pharmaceutical Preparations Containing Iron Ions
Authors: Lisik Anna , Musiał Witold
Published: March 2019

The aim of this study was to verify the effect of the formulation on the release kinetics of active substances from preparations containing iron ions using in-line conductivity measurements. A simple, fast method was developed and may be applied for detailed evaluation of some kinetics factors obtained from the release data. Four different equations were used: zero-order equation, first-order equation, models: Korsmeyer–Peppas and Hixson–Crowell. Values of the determined half-time release for zero and first-order kinetic models ranged from 11.56 to 89.97 min. In the case of analysis according to these typical models, the values of the square root of the correlation coefficients were included between 0.9916 and 0.9995. The results transformed for the Hixson–Crowell model as constant release Ks, ranged between 0.0160 and 0.0437. The values of the respective calculated squares of the correlation coefficient ranged from 0.9933 to 0.9959. The determined release rate constants according to the Korsmeyer–Peppas model were between 0.0023 and 0.1630. The coefficients ‘n’ of the Korsmeyer–Peppas equation did not exceed 1.2 with the corresponding r2 values 0.9408–0.9960. Obtained results confirmed that the method is applicable for evaluation of selected drug compositions containing iron ions.
Effect of Different Surface Treatments on Titanium Dental Implant Micro-Morphology
Authors: Marenzi Gaetano , Impero Filomena , Scherillo Fabio , Sammartino Josè Camilla , Squillace Antonino , Spagnuolo Gianrico
Published: March 2019

Background: Titanium dental implants are today widely used with osseointegration mainly dependently on the implant surface properties. Different processing routes lead to different surface characteristics resulting, of course, in different in situ behaviors of the implants. Materials: The effect of different treatments, whether mechanical or chemical, on the surface morphology of titanium implants were investigated. To this aim, various experimental methods, including roughness analysis as well scanning electron microscope (SEM) observations, were applied. Results: The results showed that, in contrast to the mechanical treatments, the chemical ones gave rise to a more irregular surface. SEM observations suggested that where commercial pure titanium was used, the chemical treatments provided implant surfaces without contaminations. In contrast, sandblasted implants could cause potential risks of surface contamination because of the presence of blasting particles remnants. Conclusions: The examined implant surfaces showed different roughness levels in relation to the superficial treatment applied. The acid-etched surfaces were characterized by the presence of deeper valleys and higher peaks than the sandblasted surfaces. For this reason, acid-etched surfaces can be more easily damaged by the stress produced by the peri-implant bone during surgical implant placement.
Theoretical Equations of Zeeman Energy Levels for Distorted Metal Complexes with 3T1 Ground Terms
Authors: Sakiyama Hiroshi
Published: March 2019

The theoretical equations of Zeeman energy levels, including the zero-field energies and the first- and second-order Zeeman coefficients, have been obtained in closed form for nine states of the 3 T 1 ( g ) ground term, considering the axial ligand-field splitting and the spin-orbit coupling. The equations are expressed as the functions of three independent parameters, Δ , λ , and κ , where Δ is the axial ligand-field splitting parameter, λ is the spin-orbit coupling parameter, and κ is the effective orbital reduction factor, including the admixing. The equations are useful in simulating magnetic properties (magnetic susceptibility and magnetization) of the complexes with 3 T 1 ( g ) ground terms, e.g., octahedral vanadium(III), octahedral low-spin manganese(III), octahedral low-spin chromium(II), and tetrahedral nickel(II) complexes.
Methods for Assessing Human–Machine Performance under Fuzzy Conditions
Authors: Voskoglou Michael Gr.
Published: March 2019

The assessment of a system’s performance is a very important task, enabling its designer/user to correct its weaknesses and make it more effective. Frequently, in practice, a system’s assessment is performed under fuzzy conditions, e.g., using qualitative instead of numerical grades, incomplete information about its function, etc. The present review summarizes the author’s research on building assessment models for use in a fuzzy environment. Those models include the measurement of a fuzzy system’s uncertainty, the application of the center of gravity defuzzification technique, the use of triangular fuzzy or grey numbers as assessment tools, and the application of the fuzzy relation equations. Examples are provided of assessing human (students and athletes) and machine (case-based reasoning systems in computers) capacities, illustrating our results. The outcomes of those examples are compared to the outcomes of the traditional methods of calculating the mean value of scores assigned to the system’s components (system’s mean performance) and of the grade point average index (quality performance) and useful conclusions are obtained concerning their advantages and disadvantages. The present review forms a new basis for further research on systems’ assessment in a fuzzy environment.
Effect of Hydrogen on the Wear Resistance of Steels upon Contact with Plasma Electrolytic Oxidation Layers Synthesized on Aluminum Alloys
Authors: Hutsaylyuk Volodymyr , Student Mykhailo , Dovhunyk Volodymyr , Posuvailo Volodymyr , Student Oleksandra , Maruschak Pavlo , Koval’chuck Ihor
Published: March 2019

The different nature of the effect of hydrogen on the tribological behavior of two carbon steels (st. 45 and st. U8) upon their contact with super solid plasma electrolytic oxidation (PEO) layers synthesized on two light alloys (AMg-6 and D16T alloys as the analogists of the A 95556 UNS USA and AA2024 ANSI USA alloys correspondently) was investigated in the medium of mineral oil of the I-20 type. To compare the effect of hydrogenation on the tribological properties of the analyzed contact pairs, similar tests were also performed on the same mineral oil with clear water or an aqueous solution of glycerine added to its content. A spinel-type film (hercynite) was formed upon friction of two contacting surfaces—the iron-carbon steels and PEO layers synthesized on the AMg-6 alloy. This film was a reliable protection against wear of the surface subjected to the effect of hydrogen. When steels came into contact with the PEO layers synthesized on the D16T alloy, surface protection against wear was ensured by another mechanism. The phenomenon of selective metal transfer in the friction zone (from one to another friction surfaces) was revealed.
Mechanical Properties of Tool Steels with High Wear Resistance via Directed Energy Deposition
Authors: Baek Gyeong Yun , Shin Gwang Yong , Lee Ki Yong , Shim Do Sik
Published: March 2019

This study focused on the mechanical and metallurgical characteristics of high-wear-resistance steel (HWS) deposited using directed energy deposition (DED) for metal substrate hardfacing or repairing. As post-deposition heat treatment changes the metallurgical characteristics of deposits, the effect of post-deposition heat treatment on the mechanical properties was investigated via microstructure observation and by conducting hardness, wear, and impact tests. The obtained micro-images showed that the deposited HWS layers exhibit cellular and columnar dendrites, and the microstructure of heat-treated HWS (HT-HWS) transformed its phase during quenching and tempering. The hardness and wear resistance of the HT-HWS deposits were higher than those of the HWS deposited specimen, whereas the latter exhibited a higher fracture toughness. The matrix microstructure and carbide characteristics, which are characterized by the chemical composition of the materials, significantly influenced the mechanical properties.
Performance of Plunge Depth Control Methods During Friction Stir Welding
Authors: Yoon Jinyoung , Kim Cheolhee , Rhee Sehun
Published: March 2019

Friction stir welding is a preferred solid state welding process for Al/Fe joints, and in friction stir lap welding, the plunge depth is the most critical parameter for joint strength. We compared three plunge depth control methods, namely conventional position control, offset position control, and deflection compensation control in the friction stir lap welding of 3 mm-thick Al 5083-O alloy over 1.2 mm-thick DP 590 steel. The desired plunge depth was 0.2 mm into the steel sheet. However, the pin did not reach the steel surface under conventional position control due to deflection of the vertical axis of the welding system. In offset position control, an additional offset of 0.35 mm could achieve the desired plunge depth with considerable accuracy. Nevertheless, a gradual increase of the plunge depth along the longitudinal direction was unavoidable, due to an in-situ decrease of the material yield strengths. In deflection compensation control, the deflection is estimated by the coaxially measured plunging force and the force-deflection relationship, and then corrected by feedback control. Thus, the plunge depth is stabilized along the longitudinal direction and is precisely controlled with a 3.3-μm standard deviation of error during the tool traverse phase. There is also a consistent bias of 32 μm caused by the resolution of the measuring system, and it can be easily calibrated in the feedback control system.
Influence of Residual Stress on Fatigue Weak Areas and Simulation Analysis on Fatigue Properties Based on Continuous Performance of FSW Joints
Authors: Sun Guoqin , Wei Xinhai , Niu Jiangpei , Shang Deguang , Chen Shujun
Published: March 2019

The fatigue weak area of aluminum alloy for a friction stir-welded joint is investigated based on the hardness profile, the residual stress measurement and the simulation analysis of fatigue property. The maximum residual stresses appeared at the heat-affected zone of the joint in the fatigue damage process, which was consistent with the fracture location of the fatigue specimen. The fatigue joint model of continuous performance is established ignoring the original negative residual stress; considering that it will be relaxed soon when the joint is under tension-tension cyclic loading. The fatigue parameters of joint model is based on the static mechanical properties of the joint that obtained from the micro-tensile tests and four-point correlation method. The predicted results for the fatigue weak locations and fatigue lives based on the continuous performance joint model are closer to the fatigue experimental results by comparison with the simulation results of the partitioned performance joint model.
Microstructure and Properties of Spot Welded Joints of Hot-Stamped Ultra-High Strength Steel Used for Automotive Body Structures
Authors: Qiao Zhixia , Li Huijun , Li Lianjin , Ran Xiaoyu , Feng Liwen
Published: March 2019

Hot-stamped ultra-high strength steels have been widely used in automobile structural parts. Considering the high splash tendency in resistance spot welding due to their extremely high hardness, in this work, microstructural characteristics and mechanical performance of the resistance spot welded ultra-high strength steels are investigated. The results indicate that the interface between the nugget and heat-affected zone (HAZ) is the weakest zone where fractures initiate. In tensile shearing tests, a qualified spot welding joint failed with a button-shaped fracture. Welding defects would significantly decrease the load-carrying capacity and lead to interfacial fracture, except for a button-shaped fracture. In spot welding, it was found that a specific mid-frequency alternating current (AC) input mode, in which a 6 ms cooling cycle was inserted between every two neighboring current pulses, can avoid the splash in the spot welding of hot-stamped hardened steels.
Characterization of Texture Evolution during Recrystallization by Laser-Induced Transient Thermal Grating Method
Authors: Yin Anmin , Xu Xiaodong , Zhang Shuyi , Glorieux Christ , Shu Xuedao , Wang Yufan , Yan Xuejun
Published: March 2019

The analyses of texture evolution of cold rolled interstitial free (IF) steel sheets during annealing and recrystallization are presented, in which the dispersion curves of surface acoustic waves (SAW) excited by laser-induced transient thermal grating method are measured. The results show that the angular anisotropy of the SAW velocity changes due to the texture changes at different stages of recrystallization. The theoretically simulated angular dispersion of SAW velocity within individual crystal revealed that the change of SAW velocity is closely related to recrystallization texture evolution. A model for the angular dependence of the SAW velocity in textured polycrystalline IF steel with different oriented crystals is presented and the simulations are yielded, which show that the results agree with those of experiments.
Maternal Dietary Docosahexaenoic Acid Alters Lipid Peroxidation Products and (n-3)/(n-6) Fatty Acid Balance in Offspring Mice
Authors: Yang Bo , Li Runting , Woo Taeseon , Browning Jimmy D. , Song Hailong , Gu Zezong , Cui Jiankun , Lee James C. , Fritsche Kevin L. , Beversdorf David Q. , Sun Grace Y. , Greenlief C. Michael
Published: March 2019

The abundance of docosahexaenoic acid (DHA) in the mammalian brain has generated substantial interest in the search for its roles in regulating brain functions. Our recent study with a gene/stress mouse model provided evidence to support the ability for the maternal supplement of DHA to alleviate autism-associated behavior in the offspring. DHA and arachidonic acid (ARA) are substrates of enzymatic and non-enzymatic reactions, and lipid peroxidation results in the production of 4-hydroxyhexenal (4-HHE) and 4-hydroxynonenal (4-HNE), respectively. In this study, we examine whether a maternal DHA-supplemented diet alters fatty acids (FAs), as well as lipid peroxidation products in the pup brain, heart and plasma by a targeted metabolite approach. Pups in the maternal DHA-supplemented diet group showed an increase in DHA and a concomitant decrease in ARA in all brain regions examined. However, significant increases in 4-HHE, and not 4-HNE, were found mainly in the cerebral cortex and hippocampus. Analysis of heart and plasma showed large increases in DHA and 4-HHE, but a significant decrease in 4-HNE levels only in plasma. Taken together, the DHA-supplemented maternal diet alters the (n-3)/(n-6) FA ratio, and increases 4-HHE levels in pup brain, heart and plasma. These effects may contribute to the beneficial effects of DHA on neurodevelopment, as well as functional changes in other body organs.
Charged Satellite Drop Avoidance in Electrohydrodynamic Dripping
Authors: Guo Lei , Duan Yongqing , Deng Weiwei , Guan Yin , Huang YongAn , Yin Zhouping
Published: March 2019

The quality of electrohydrodynamic jet (e-jet) printing is crucially influenced by the satellite drop formed when the primary drop detaches from the meniscus. If the satellite drop falls onto the substrate, the patterns on the substrate will be contaminated. The electric charge carried by the satellite drop leads to more complex satellite/meniscus interaction than that in traditional inkjet printing. Here, we numerically study the formation and flight behavior of the charged satellite drop. This paper discovered that the charge relaxation time (CRT) of the liquid determines the electric repulsion force between the satellite drop and meniscus. The satellite drop will merge with the meniscus at long CRT, and fail to merge and deteriorate the printing quality at short CRT. The simulations are adopted to discover the mechanism of generation and flight behavior of charged satellite drops. The results show that the critical CRT decreases with the dielectric constant of the liquid and the supplied flow rate. Namely, for small dielectric constant and fixed CRT, the satellite drop is less likely to merge with the meniscus, and for high flow rate, the satellite drop is prone to merge with the meniscus due to the delay of necking thread breakup. These results will help to choose appropriate parameters to avoid the satellite drop from falling onto the substrate.
Bias-Modulated High Photoelectric Response of Graphene-Nanocrystallite Embedded Carbon Film Coated on n-Silicon
Authors: Zhang Xi , Lin Zezhou , Peng Da , Diao Dongfeng
Published: March 2019

We propose that bias-modulated graphene-nanocrystallites (GNs) grown vertically can enhance the photoelectric property of carbon film coated on n-Si substrate. In this work, GN-embedded carbon (GNEC) films were deposited by the electron cyclotron resonance (ECR) sputtering technique. Under a reverse diode bias which lifts the Dirac point of GNs to a higher value, the GNEC film/n-Si device achieved a high photocurrent responsivity of 0.35 A/W. The bias-modulated position of the Dirac point resulted in a tunable ON/OFF ratio and a variable spectral response peak. Moreover, due to the standing structured GNs keeping the transport channels, a response time of 2.2 μs was achieved. This work sheds light on the bias-control wavelength-sensitive photodetector applications.
Antifriction and Antiwear Effect of Lamellar ZrS2 Nanobelts as Lubricant Additives
Authors: Tang Wei , Yu Chuang , Zhang Shaogang , Liu Songyong , Wu Xingcai , Zhu Hua
Published: March 2019

In this study, the tribological behavior of lamellar ZrS2 nanobelts as lubricant additives was investigated under different concentrations, normal load, velocity, and temperature. The friction and wear tests were performed using a tribometer and with a reciprocating motion. The results indicate that the lamellar ZrS2 nanobelt additives can effectively reduce the coefficient of friction and running-in time during the running-in period. With the addition of ZrS2, the wear volumes decrease significantly. The wear is mostly influenced by the tribological performance throughout the running-in period. The lower the running-in time and coefficient of friction are during the running-in period, the less amount of wear is shown. ZrS2 can significantly increase the load-carrying capacity of oil. The 1.0 wt% concentration of ZrS2 yields the best antifriction effect, antiwear performance, and load-carrying capacity. The ZrS2 additives can increase the working temperature of the oil. The friction-reducing and antiwear mechanisms of lamellar ZrS2 were discussed.
Hybrid Nanodisk Film for Ultra-Narrowband Filtering, Near-Perfect Absorption and Wide Range Sensing
Authors: Cui Wenli , Peng Wei , Yu Li , Luo Xiaolin , Gao Huixuan , Chu Shuwen , Masson Jean-Francois
Published: March 2019

The miniaturization and integration of photonic devices are new requirements in the novel optics field due to the development of photonic information technology. In this paper, we report that a multifunctional layered structure of Au, SiO2 and hexagonal nanodisk film is advantageous for ultra-narrowband filtering, near-perfect absorption and sensing in a wide refractive index (RI) region. This hexagonal nanostructure presented two remarkable polarization independent plasmon resonances with near-zero reflectivity and near-perfect absorptivity under normal incidence in the visible and near-infrared spectral ranges. The narrowest full width at half maximum (FWHM) of these resonances was predicted to be excellent at 5 nm. More notably, the double plasmon resonances showed extremely obvious differences in RI responses. For the first plasmon resonance, an evident linear redshift was observed in a wide RI range from 1.00 to 1.40, and a high RI sensitivity of 600 nm/RIU was obtained compared to other plasmonic nanostructures, such as square and honeycomb-like nanostructures. For the second plasmon resonance with excellent FWHM at 946 nm, its wavelength position almost remained unmovable in the case of changing RI surrounding nanodisks in the same regime. Most unusually, its resonant wavelength was insensitive to nearly all structural parameters except the structural period. The underlying physical mechanism was analyzed in detail for double plasmon resonances. This work was significant in developing high-performance integrated optical devices for filtering, absorbing and biomedical sensing.
Effect of Defects on the Mechanical and Thermal Properties of Graphene
Authors: Li Maoyuan , Deng Tianzhengxiong , Zheng Bing , Zhang Yun , Liao Yonggui , Zhou Huamin
Published: March 2019

In this study, the mechanical and thermal properties of graphene were systematically investigated using molecular dynamic simulations. The effects of temperature, strain rate and defect on the mechanical properties, including Young’s modulus, fracture strength and fracture strain, were studied. The results indicate that the Young’s modulus, fracture strength and fracture strain of graphene decreased with the increase of temperature, while the fracture strength of graphene along the zigzag direction was more sensitive to the strain rate than that along armchair direction by calculating the strain rate sensitive index. The mechanical properties were significantly reduced with the existence of defect, which was due to more cracks and local stress concentration points. Besides, the thermal conductivity of graphene followed a power law of λ~L0.28, and decreased monotonously with the increase of defect concentration. Compared with the pristine graphene, the thermal conductivity of defective graphene showed a low temperature-dependent behavior since the phonon scattering caused by defect dominated the thermal properties. In addition, the corresponding underlying mechanisms were analyzed by the stress distribution, fracture structure during the deformation and phonon vibration power spectrum.
Complex Dynamics of Photoinduced Mass Transport and Surface Relief Gratings Formation
Authors: Pawlik Grzegorz , Wysoczanski Tomasz , Mitus Antoni C.
Published: March 2019

The microscopic and semi-macroscopic mechanisms responsible for photoinduced mass transport in functionalized azo-polymers are far from deeply understood. To get some insight into those mechanisms on “microscopic” scale, we studied the directed photoinduced motion of single functionalized polymer chains under various types of polarized light illumination using Monte Carlo bond fluctuation model and our kinetic Monte Carlo model for photoinduced mass transport. We found sub-diffusive, diffusive and super-diffusive regimes of the dynamics of single chains at constant illumination and mostly super-diffusive regime for directed motion in the presence of the gradient of light intensity. This regime is more enhanced for long than for short chains and it approaches the ballistic limit for very long chains. We propose a physical picture of light-driven inscription of Surface Relief Gratings (SRG) as corresponding to a dynamical coexistence of normal and anomalous diffusion in various parts of the system. A simple continuous time random walk model of SRG inscription based on this physical picture reproduced the light-driven mass transport found in experiments as well as the fine structure of SRG.
Structural Basis of CO2 Adsorption in a Flexible Metal-Organic Framework Material
Authors: Allen Andrew J. , Wong-Ng Winnie , Cockayne Eric , Culp Jeffrey T. , Matranga Christopher
Published: March 2019

This paper reports on the structural basis of CO2 adsorption in a representative model of flexible metal-organic framework (MOF) material, Ni(1,2-bis(4-pyridyl)ethylene)[Ni(CN)4] (NiBpene or PICNIC-60). NiBpene exhibits a CO2 sorption isotherm with characteristic hysteresis and features on the desorption branch that can be associated with discrete structural changes. Various gas adsorption effects on the structure are demonstrated for CO2 with respect to N2, CH4 and H2 under static and flowing gas pressure conditions. For this complex material, a combination of crystal structure determination and density functional theory (DFT) is needed to make any real progress in explaining the observed structural transitions during adsorption/desorption. Possible enhancements of CO2 gas adsorption under supercritical pressure conditions are considered, together with the implications for future exploitation. In situ operando small-angle neutron and X-ray scattering, neutron diffraction and X-ray diffraction under relevant gas pressure and flow conditions are discussed with respect to previous studies, including ex situ, a priori single-crystal X-ray diffraction structure determination. The results show how this flexible MOF material responds structurally during CO2 adsorption; single or dual gas flow results for structural change remain similar to the static (Sieverts) adsorption case, and supercritical CO2 adsorption results in enhanced gas uptake. Insights are drawn for this representative flexible MOF with implications for future flexible MOF sorbent design.
Silver-Nanocellulose Composite Used as SERS Substrate for Detecting Carbendazim
Authors: Huang Luqiang , Wu Changji , Xie Lijuan , Yuan Xue , Wei Xinyu , Huang Qun , Chen Youqiang , Lu Yudong
Published: March 2019

Nanocellulose is an abundant green resource that, owing to the larger surface area, length, and diameter of the fibers, can be used as a framework for loading Ag nanoparticles and serve as substrate for surface enhancement Raman scattering (SERS). These properties would cause the hydroxyl groups on the surface to adsorb the Ag ions and reduce them to Ag seed to form a load fulcrum. This paper presents a convenient and environmentally friendly method for the fabrication of silver-nanocellulose composites (NCF-Ag). A commonly used pesticide, carbendazim (CBZ), was used as a SERS probe to evaluate the properties of NCF-Ag. The results showed that NCF-Ag possesses good homogeneity, reproducibility, and stability. Additionally, CBZ was found to have a low limit of detection (LOD), i.e., 1.0 × 10−8 M, which indicates the possibility for trace analysis. Furthermore, it presents good linearity with R2 = 0.98 at 1007 and 1270 cm−1 in the range from 10−4~10−7 M CBZ.