bluuebunny/crossref_metadata_2025 huggingface dataset:
Current Age, Age at First Sex, Age at First Homelessness, and HIV Risk Perceptions Predict Sexual Risk Behaviors among Sexually Active Homeless Adults
Authors: Santa Maria Diane , Hernandez Daphne , Arlinghaus Katherine , Gallardo Kathryn , Maness Sarah , Kendzor Darla , Reitzel Lorraine , Businelle Michael
Published: January 2018

While HIV disproportionately impacts homeless individuals, little is known about the prevalence of HIV risk behaviors in the southwest and how age factors and HIV risk perceptions influence sexual risk behaviors. We conducted a secondary data analysis (n = 460) on sexually active homeless adults from a cross-sectional study of participants (n = 610) recruited from homeless service locations, such as shelters and drop-in centers, in an understudied region of the southwest. Covariate-adjusted logistic regressions were used to assess the impact of age at homelessness onset, current age, age at first sex, and HIV risk perceptions on having condomless sex, new sexual partner(s), and multiple sexual partners (≥4 sexual partners) in the past 12 months. Individuals who first experienced homelessness by age 24 were significantly more likely to report condomless sex and multiple sexual partners in the past year than those who had a later onset of their first episode of homelessness. Individuals who were currently 24 years or younger were more likely to have had condomless sex, new sexual partners, and multiple sexual partners in the past 12 months than those who were 25 years or older. Those who had low perceived HIV risk had lower odds of all three sexual risk behaviors. Social service and healthcare providers should consider a younger age at homelessness onset when targeting HIV prevention services to youth experiencing homelessness.
Quality of Life (QoL) Survey in Hong Kong: Understanding the Importance of Housing Environment and Needs of Residents from Different Housing Sectors
Authors: Gou Zhonghua , Xie Xiaohuan , Lu Yi , Khoshbakht Maryam
Published: January 2018

This study presents a Quality of Life (QoL) survey to understand the influence of the housing environment and needs of residents from different housing sectors. The research focuses on Hong Kong where living conditions have become the main affect for people’s QoL. Through a household survey using a standard instrument “Word Health Organisation (WHO) Quality of Life-BREF”, the article found that among the four WHO QoL domains (Physical Health, Psychological Health, Social Relations And Environment), Environment, particularly its constitute aspect housing environment was the most influential factor for overall quality of life for the public rental housing sector where low-income people live. This research also found that different groups of people have differing needs of their housing environments: the low-income group needs better location and privacy while the medium and high-income groups need better architectural quality. Based on differentiating their needs and wants, this research argues for prioritizing the low-income group’s needs for effectively improving their QoL.
Environmental Regulation, Foreign Direct Investment and Green Technological Progress—Evidence from Chinese Manufacturing Industries
Authors: Hu Jiangfeng , Wang Zhao , Lian Yuehan , Huang Qinghua
Published: January 2018

This study examines the spillover effects of foreign direct investment (FDI) on green technology progress rate (as measured by the green total factor productivity). The analysis utilizes two measures of FDI, labor-based FDI and capital-based FDI, and separately investigates four sets of industry classifications—high/low discharge regulation and high/low emission standard regulation. The results indicate that in the low discharge regulation and low emission standard regulation industry, labor-based FDI has a significant negative spillover effect, and capital-based FDI has a significant positive spillover effect. However, in the high-intensity environmental regulation industry, the negative influence of labor-based FDI is completely restrained, and capital-based FDI continues to play a significant positive green technological spillover effects. These findings have clear policy implications: the government should be gradually reducing the labor-based FDI inflow or increasing stringency of environmental regulation in order to reduce or eliminate the negative spillover effect of the labor-based FDI.
An Online Survey of New Zealand Vapers
Authors: Truman Penelope , Glover Marewa , Fraser Trish
Published: January 2018

Using electronic cigarettes (vaping) is controversial, but is increasingly widespread. This paper reports the results of an electronic survey of vapers in New Zealand, a country where the sale and supply of e-liquids containing nicotine is illegal, although vapers can legally access e-liquids from overseas. An on-line survey was conducted, using vaper and smoking cessation networks for recruitment, with follow up surveys conducted 1 and 2 months after the initial survey. 218 participants were recruited. Almost all had been smokers, but three quarters no longer smoked, with the remainder having significantly reduced their tobacco use. Three participants were non-smokers before starting to vape, but none had gone on to become smokers. The overriding motivation to begin and continue vaping was to stop or to reduce smoking. The results were consistent with a progression from initially both vaping and smoking using less effective electronic cigarette types, then moving to more powerful devices, experimentation with flavors and nicotine strengths—all resulting in reducing or stopping tobacco use. Lack of access to nicotine and lack of support for their chosen cessation method were the main problems reported. Vaping had resulted in effective smoking cessation for the majority of participants.
A Space-Time Periodic Task Model for Recommendation of Remote Sensing Images
Authors: Zhang Xiuhong , Chen Di , Liu Jiping
Published: January 2018

With the rapid development of remote sensing technology, the quantity and variety of remote sensing images are growing so quickly that proactive and personalized access to data has become an inevitable trend. One of the active approaches is remote sensing image recommendation, which can offer related image products to users according to their preference. Although multiple studies on remote sensing retrieval and recommendation have been performed, most of these studies model the user profiles only from the perspective of spatial area or image features. In this paper, we propose a spatiotemporal recommendation method for remote sensing data based on the probabilistic latent topic model, which is named the Space-Time Periodic Task model (STPT). User retrieval behaviors of remote sensing images are represented as mixtures of latent tasks, which act as links between users and images. Each task is associated with the joint probability distribution of space, time and image characteristics. Meanwhile, the von Mises distribution is introduced to fit the distribution of tasks over time. Then, we adopt Gibbs sampling to learn the random variables and parameters and present the inference algorithm for our model. Experiments show that the proposed STPT model can improve the capability and efficiency of remote sensing image data services.
Autoimmunity and Gastric Cancer
Authors: Bizzaro Nicola , Antico Antonio , Villalta Danilo
Published: January 2018

Alterations in the immune response of patients with autoimmune diseases may predispose to malignancies, and a link between chronic autoimmune gastritis and gastric cancer has been reported in many studies. Intestinal metaplasia with dysplasia of the gastric corpus-fundus mucosa and hyperplasia of chromaffin cells, which are typical features of late-stage autoimmune gastritis, are considered precursor lesions. Autoimmune gastritis has been associated with the development of two types of gastric neoplasms: intestinal type and type I gastric carcinoid. Here, we review the association of autoimmune gastritis with gastric cancer and other autoimmune features present in gastric neoplasms.
Resistance to the Antiproliferative In Vitro Effect of PI3K-Akt-mTOR Inhibition in Primary Human Acute Myeloid Leukemia Cells Is Associated with Altered Cell Metabolism
Authors: Nepstad Ina , Reikvam Håkon , Brenner Annette , Bruserud Øystein , Hatfield Kimberley
Published: January 2018

Constitutive signaling through the phosphatidylinositol-3-kinase-Akt-mechanistic target of rapamycin (PI3K-Akt-mTOR) pathway is present in acute myeloid leukemia (AML) cells. However, AML is a heterogeneous disease, and we therefore investigated possible associations between cellular metabolism and sensitivity to PI3K-Akt-mTOR pathway inhibitors. We performed non-targeted metabolite profiling to compare the metabolome differences of primary human AML cells derived from patients susceptible or resistant to the in vitro antiproliferative effects of mTOR and PI3K inhibitors. In addition, the phosphorylation status of 18 proteins involved in PI3K-Akt-mTOR signaling and the effect of the cyclooxygenase inhibitor indomethacin on their phosphorylation status was investigated by flow cytometry. Strong antiproliferative effects by inhibitors were observed only for a subset of patients. We compared the metabolite profiles for responders and non-responders towards PI3K-mTOR inhibitors, and 627 metabolites could be detected. Of these metabolites, 128 were annotated and 15 of the annotated metabolites differed significantly between responders and non-responders, including metabolites involved in energy, amino acid, and lipid metabolism. To conclude, leukemia cells that are susceptible or resistant to PI3K-Akt-mTOR inhibitors differ in energy, amino acid, and arachidonic acid metabolism, and modulation of arachidonic acid metabolism alters the activation of mTOR and its downstream mediators.
VEGF Triggers the Activation of Cofilin and the Arp2/3 Complex within the Growth Cone
Authors: Schlau Matthias , Terheyden-Keighley Daniel , Theis Verena , Mannherz Hans Georg , Theiss Carsten
Published: January 2018

A crucial neuronal structure for the development and regeneration of neuronal networks is the axonal growth cone. Affected by different guidance cues, it grows in a predetermined direction to reach its final destination. One of those cues is the vascular endothelial growth factor (VEGF), which was identified as a positive effector for growth cone movement. These positive effects are mainly mediated by a reorganization of the actin network. This study shows that VEGF triggers a tight colocalization of cofilin and the Arp2/3 complex to the actin cytoskeleton within chicken dorsal root ganglia (DRG). Live cell imaging after microinjection of GFP (green fluorescent protein)-cofilin and RFP (red fluorescent protein)-LifeAct revealed that both labeled proteins rapidly redistributed within growth cones, and showed a congruent distribution pattern after VEGF supplementation. Disruption of signaling upstream of cofilin via blocking LIM-kinase (LIMK) activity resulted in growth cones displaying regressive growth behavior. Microinjection of GFP-p16b (a subunit of the Arp2/3 complex) and RFP-LifeAct revealed that both proteins redistributed into lamellipodia of the growth cone within minutes after VEGF stimulation. Disruption of the signaling to the Arp2/3 complex in the presence of VEGF by inhibition of N-WASP (neuronal Wiskott–Aldrich–Scott protein) caused retraction of growth cones. Hence, cofilin and the Arp2/3 complex appear to be downstream effector proteins of VEGF signaling to the actin cytoskeleton of DRG growth cones. Our data suggest that VEGF simultaneously affects different pathways for signaling to the actin cytoskeleton, since activation of cofilin occurs via inhibition of LIMK, whereas activation of Arp2/3 is achieved by stimulation of N-WASP.
A Simple Method to Reduce both Lactic Acid and Ammonium Production in Industrial Animal Cell Culture
Authors: Freund Nathaniel , Croughan Matthew
Published: January 2018

Fed-batch animal cell culture is the most common method for commercial production of recombinant proteins. However, higher cell densities in these platforms are still limited due to factors such as excessive ammonium production, lactic acid production, nutrient limitation, and/or hyperosmotic stress related to nutrient feeds and base additions to control pH. To partly overcome these factors, we investigated a simple method to reduce both ammonium and lactic acid production—termed Lactate Supplementation and Adaptation (LSA) technology—through the use of CHO cells adapted to a lactate-supplemented medium. Using this simple method, we achieved a reduction of nearly 100% in lactic acid production with a simultaneous 50% reduction in ammonium production in batch shaker flasks cultures. In subsequent fed-batch bioreactor cultures, lactic acid production and base addition were both reduced eight-fold. Viable cell densities of 35 million cells per mL and integral viable cell days of 273 million cell-days per mL were achieved, both among the highest currently reported for a fed-batch animal cell culture. Investigating the benefits of LSA technology in animal cell culture is worthy of further consideration and may lead to process conditions more favorable for advanced industrial applications.
Unravelling Immunoglobulin G Fc N-Glycosylation: A Dynamic Marker Potentiating Predictive, Preventive and Personalised Medicine
Authors: Russell Alyce , Adua Eric , Ugrina Ivo , Laws Simon , Wang Wei
Published: January 2018

Multiple factors influence immunoglobulin G glycosylation, which in turn affect the glycoproteins’ function on eliciting an anti-inflammatory or pro-inflammatory response. It is prudent to underscore these processes when considering the use of immunoglobulin G N-glycan moieties as an indication of disease presence, progress, or response to therapeutics. It has been demonstrated that the altered expression of genes that encode enzymes involved in the biosynthesis of immunoglobulin G N-glycans, receptors, or complement factors may significantly modify immunoglobulin G effector response, which is important for regulating the immune system. The immunoglobulin G N-glycome is highly heterogenous; however, it is considered an interphenotype of disease (a link between genetic predisposition and environmental exposure) and so has the potential to be used as a dynamic biomarker from the perspective of predictive, preventive, and personalised medicine. Undoubtedly, a deeper understanding of how the multiple factors interact with each other to alter immunoglobulin G glycosylation is crucial. Herein we review the current literature on immunoglobulin G glycoprotein structure, immunoglobulin G Fc glycosylation, associated receptors, and complement factors, the downstream effector functions, and the factors associated with the heterogeneity of immunoglobulin G glycosylation.
A Comparative Study of Web Content Management Systems
Authors: Martinez-Caro Jose-Manuel , Aledo-Hernandez Antonio-Jose , Guillen-Perez Antonio , Sanchez-Iborra Ramon , Cano Maria-Dolores
Published: January 2018

Web Content Management Systems (WCMS) play an increasingly important role in the Internet’s evolution. They are software platforms that facilitate the implementation of a web site or an e-commerce and are gaining popularity due to its flexibility and ease of use. In this work, we explain from a tutorial perspective how to manage WCMS and what can be achieved by using them. With this aim, we select the most popular open-source WCMS; namely, Joomla!, WordPress, and Drupal. Then, we implement three websites that are equal in terms of requirements, visual aspect, and functionality, one for each WCMS. Through a qualitative comparative analysis, we show the advantages and drawbacks of each solution, and the complexity associated. On the other hand, security concerns can arise if WCMS are not appropriately used. Due to the key position that they occupy in today’s Internet, we perform a basic security analysis of the three implement websites in the second part of this work. Specifically, we explain vulnerabilities, security enhancements, which errors should not be done, and which WCMS is initially safer.
Experimental Analysis of Stemming on Jurisprudential Documents Retrieval
Authors: N. de Oliveira Robert , C. Junior Methanias
Published: January 2018

Stemming algorithms are commonly used during textual preprocessing phase in order to reduce data dimensionality. However, this reduction presents different efficacy levels depending on the domain that it is applied to. Thus, for instance, there are reports in the literature that show the effect of stemming when applied to dictionaries or textual bases of news. On the other hand, we have not found any studies analyzing the impact of radicalization on Brazilian judicial jurisprudence, composed of decisions handed down by the judiciary, a fundamental instrument for law professionals to play their role. Thus, this work presents two complete experiments, showing the results obtained through the analysis and evaluation of the stemmers applied on real jurisprudential documents, originating from the Court of Justice of the State of Sergipe. In the first experiment, the results showed that, among the analyzed algorithms, the RSLP (Removedor de Sufixos da Lingua Portuguesa) possessed the greatest capacity of dimensionality reduction of the data. In the second one, through the evaluation of the stemming algorithms on the legal documents retrieval, the RSLP-S (Removedor de Sufixos da Lingua Portuguesa Singular) and UniNE (University of Neuchâtel), less aggressive stemmers, presented the best cost-benefit ratio, since they reduced the dimensionality of the data and increased the effectiveness of the information retrieval evaluation metrics in one of analyzed collections.
Effect of Low Spin Excited States for Magnetic Anisotropy of Transition Metal Mononuclear Single Molecule Magnets
Authors: Llanos Leonel , Aravena Daniel
Published: January 2018

Rational, fine tuning of magnetic anisotropy is critical to obtain new coordination compounds with enhanced single molecule magnet properties. For mononuclear transition metal complexes, the largest contribution to zero-field splitting is usually related to the excited states of the same spin as the ground level. Thus, the contribution of lower multiplicity roots tends to be overlooked due to its lower magnitude. In this article, we explore the role of lower multiplicity excited states in zero-field splitting parameters in model structures of Fe(II) and Co(II). Model aquo complexes with coordination numbers ranging from 2 to 6 were constructed. The magnetic anisotropy was calculated by state of the art ab initio methodologies, including spin-orbit coupling effects. For non-degenerate ground states, contributions to the zero-field splitting parameter (D) from highest and lower multiplicity roots were of the same sign. In addition, their relative magnitude was in a relatively narrow range, irrespective of the coordination geometry. For degenerate ground states, the contribution from lower multiplicity roots was significantly smaller. Results are rationalized in terms of general expressions for D and are expected to be reasonably transferable to real molecular systems.
A Molecular Method for the Identification of Honey Bee Subspecies Used by Beekeepers in Russia
Authors: Syromyatnikov Mikhail , Borodachev Anatoly , Kokina Anastasia , Popov Vasily
Published: January 2018

Apis mellifera L. includes several recognized subspecies that differ in their biological properties and agricultural characteristics. Distinguishing between honey bee subspecies is complicated. We analyzed the Folmer region of the COX1 gene in honey bee subspecies cultivated at bee farms in Russia and identified subspecies-specific SNPs. DNA analysis revealed two clearly distinct haplogroups in A. mellifera mellifera. The first one was characterized by multiple cytosine-thymine (thymine–cytosine) transitions, one adenine-guanine substitution, and one thymine–adenine substitution. The nucleotide sequence of the second haplogroup coincided with sequences from other subspecies, except the unique C/A SNP at position 421 of the 658-bp Folmer region. A. mellifera carnica and A. mellifera carpatica could be distinguished from A. mellifera mellifera and A. mellifera caucasica by the presence of the A/G SNP at position 99 of the 658-bp Folmer region. The G/A SNP at position 448 was typical for A. mellifera carnica. A. mellifera caucasica COX1 sequence lacked all the above-mentioned sites. We developed a procedure for rapid identification of honey bee subspecies by PCR with restriction fragment length polymorphism (RFLP) using mutagenic primers. The developed molecular method for honey bee subspecies identification is fast and inexpensive.
Growing Industries, Growing Invasions? The Case of the Argentine Ant in Vineyards of Northern Argentina
Authors: Schulze-Sylvester Maria , Corronca José , Paris Carolina
Published: January 2018

The invasive Argentine ant causes ecological and economic damage worldwide. In 2011, this species was reported in vineyards of Cafayate, a wine-producing town in the Andes, Argentina. While the local xeric climate is unsuitable for Argentine ants, populations could establish in association with vineyards where human activity and irrigation facilitate propagule introduction and survival. In 2013–2014, we combined extensive sampling of the area using ant-baits with monitoring of the change in land use and vineyard cultivated area over the past 15 years. Our results revealed that the species has thus far remained confined to a relatively isolated small area, owing to an effective barrier of dry shrublands surrounding the infested vineyards; yet the recent expansion of vineyard acreage in this region will soon connect this encapsulated area with the rest of the valley. When this happens, vulnerable ecosystems and the main local industry will be put at risk. This case provides a rare opportunity to study early invasion dynamics and reports, to the best of our knowledge, for the first time, the Argentine ant in high altitude agroecosystems.
Fear and Disgust of Spiders: Factors that Limit University Preservice Middle School Science Teachers
Authors: Wagler Ron , Wagler Amy
Published: January 2018

Spiders perform many essential ecological services, yet humans often experience negative emotions toward spiders. These emotions can lead to the avoidance of beneficial events. These emotions may affect beliefs about what should or should not be included in a science curriculum. This study investigated how activities with living spiders affected preservice middle school science teachers’ emotions and beliefs. Prior to the activities both groups (i.e., treatment and control) had moderate to extreme fear and disgust toward the spider. The teachers that participated in the spider activities (i.e., treatment group) had much lower levels of fear and disgust after performing the spider activities than the control group that did not participate in the spider activities. The control group continued to have elevated levels of fear and disgust toward the spider throughout the study. Before the spider activities neither group planned to incorporate information about spiders or information about the essential ecological services of spiders into their science classroom. After the treatment group participated in the spider activities, the teachers had definitive plans to teach their students about spiders and the essential ecological services that they provide. The control group remained unchanged and had no plans to teach this information to their students.
Inclusive Businesses and Land Reform: Corporatization or Transformation?
Authors: Chamberlain Wytske , Anseeuw Ward
Published: January 2018

Inclusive businesses (IBs), embodying partnerships between commercial agribusinesses and smallholder farmers/low-income communities, are considered to contribute towards rural development and agricultural sector transformation. Structured as complex organizational set-ups consisting of, and overcoming the limitations of, standard inclusive instruments (collective organization, mentorship, supply contract, lease/management contract and equity), they allow for the inclusion of smallholders and low-income communities into commercial agricultural value chains. IBs are a way for governments to engage private agribusinesses in agricultural and rural policies. However, will the commercial sector, through IB partnerships, contribute towards the government’s transformation and developmental objectives? Based on case studies in South Africa—a country engaged in land and agrarian reforms—the effects of IBs at the project level appear positive, illustrated by an increase in production and growth in agricultural assets. However, individual beneficiaries experience only a marginal change in income and livelihoods. Whereas land reform, project development and market integration are generally achieved, the transformation and beneficiary development objectives are compromised. Although commercial agribusinesses contribute to investment needs in the sector and smallholder exposure to commercial markets, IB partnerships allow commercial entities control over the smallholders’ assets. Ownership and secure rights, especially of land, and support of external parties to capacitate beneficiaries and adjust power asymmetries, are essential starting points. Without these aspects, IBs will not lead to effective transformation and development.
Acknowledgement to Reviewers of Laws in 2017
Authors:   Laws Editorial Office
Published: January 2018

Peer review is an essential part in the publication process, ensuring that Laws maintains high quality standards for its published papers.[...]
Sustainability of a Compartmentalized Host-Parasite Replicator System under Periodic Washout-Mixing Cycles
Authors: Furubayashi Taro , Ichihashi Norikazu
Published: January 2018

The emergence and dominance of parasitic replicators are among the major hurdles for the proliferation of primitive replicators. Compartmentalization of replicators is proposed to relieve the parasite dominance; however, it remains unclear under what conditions simple compartmentalization uncoupled with internal reaction secures the long-term survival of a population of primitive replicators against incessant parasite emergence. Here, we investigate the sustainability of a compartmentalized host-parasite replicator (CHPR) system undergoing periodic washout-mixing cycles, by constructing a mathematical model and performing extensive simulations. We describe sustainable landscapes of the CHPR system in the parameter space and elucidate the mechanism of phase transitions between sustainable and extinct regions. Our findings revealed that a large population size of compartments, a high mixing intensity, and a modest amount of nutrients are important factors for the robust survival of replicators. We also found two distinctive sustainable phases with different mixing intensities. These results suggest that a population of simple host–parasite replicators assumed before the origin of life can be sustained by a simple compartmentalization with periodic washout-mixing processes.
CFD Modeling of the Effect of Different Surface Texturing Geometries on the Frictional Behavior
Authors: Vilhena Luís , Sedlaček Marko , Podgornik Bojan , Rek Zlatko , Žun Iztok
Published: January 2018

In order to understand the effect of surface texturing parameters on the frictional behavior of textured surfaces and to correlate results of different lubrication regimes, Computational Fluid Dynamics (CFD) numerical analysis of the fluid flow was performed for four different textured surface geometries. The aim of the present research paper is to get theoretical background for the frictional behavior of textured surfaces under hydrodynamic lubrication. Since it is unrealistic to make a direct analysis of a real problem that can possess more than several thousand micro-dimples, the purpose is then to investigate the flow in single cells of periodical micro-dimple patterns and to extract useful conclusions for the lubrication’s framework. Among all geometries studied, optimum geometry shapes in terms of hydrodynamic performance were reported. It was found that the best hydrodynamic performance was achieved with the rectangular geometry (lowest shear force).
Phase Transformation Induced Self-Healing Behavior of Al-Ag Alloy
Authors: Michalcová Alena , Marek Ivo , Knaislová Anna , Sofer Zdeněk , Vojtěch Dalibor
Published: January 2018

Self-healing alloys are promising materials that can decrease the consequences of accidents. To detect crack formation in a material is simple task that can be performed by e.g., sonic or ultrasound detection, but it is not always possible to immediately replace the damaged parts. In this situation, it is very advantageous to have the chance to heal the crack during operation, which can be done e.g., by annealing. In this paper, self-healing behavior was proven by TEM (Transmission electron microscope) observation of crack healing after annealing. The crack was observed in the rapidly solidified Al-30Ag alloy with non-equilibrium phase composition formed by a minor amount of Ag2Al and a supersaturated solid solution of Ag in an fcc-Al matrix (fcc = face centered cubic). After annealing at 450 °C, equilibrium phase composition was obtained by forming a higher amount of Ag2Al. This phase transformation did not allow the crack to be healed. Subsequent annealing at 550 °C caused recrystallization to a supersaturated solid solution of Ag in fcc-Al, followed by a return to the mixture of fcc-Al and Ag2Al by cooling, and this process was accompanied by the closing of the crack. This observation proved the self-healing possibilities of the Ag2Al phase. Practical application of this self-healing behavior could be achieved through the dispersion of fine Ag2Al particles in a structural material, which will enrich the material with self-healing properties.
Investigation of the Microstructure Evolution and Deformation Mechanisms of a Mg-Zn-Zr-RE Twin-Roll-Cast Magnesium Sheet by In-Situ Experimental Techniques
Authors: Máthis Kristián , Horváth Klaudia , Farkas Gergely , Choe Heeman , Shin Kwang , Vinogradov Alexei
Published: January 2018

Twin roll casting (TRC), with a relatively fast solidification rate, is an excellent production method with promising potential for producing wrought semi or final Mg alloy products that can often suffer from poor formability. We investigate in this study the effect of the TRC method and the subsequent heat treatment on the microstructure and deformation mechanisms in Mg-Zn-Zr-Nd alloy deformed at room temperature using the in-situ neutron diffraction and acoustic emission techniques and ex-situ texture measurement and microscopy, respectively. Although a higher work hardening is observed in the rolling direction due to the more intensive -type dislocation activity, the difference in the mechanical properties of the specimens deformed in the RD and TD directions is small in the as-rolled condition. An additional heat treatment results in recrystallization and significant anisotropy in the deformation. Due to the easier activation of the extension twinning in the TD given by texture, the yield stress in the TD is approximately 40% lower than that in the RD.
Relationship between the Size of the Samples and the Interpretation of the Mercury Intrusion Results of an Artificial Sandstone
Authors: Dong Hua , Zhang Hongzhi , Zuo Yibing , Gao Peng , Ye Guang
Published: January 2018

Mercury intrusion porosimetry (MIP) measurements are widely used to determine pore throat size distribution (PSD) curves of porous materials. The pore throat size of porous materials has been used to estimate their compressive strength and air permeability. However, the effect of sample size on the determined PSD curves is often overlooked. In pursuit of a better understanding of the effect of sample size on mercury intrusion into porous materials, a combined experimental and numerical approach was applied. Quartz sand and epoxy resin were mixed to form artificial sandstone. Digital microstructures of the sandstone were obtained by using X-ray computed tomography (CT scan) technique. PSD curves of the artificial sandstone with different sample sizes were determined both by MIP measurement and by simulation of mercury intrusion (i.e., MIP simulation). Percolation analysis was performed on mercury-intruded pores in the digital microstructures. The PSD curves determined both by MIP measurements and by MIP simulations show that there was a significant effect of sample size on mercury intrusion before percolation of mercury-intruded pores. The effect of sample size decreased with the increasing pressure. After the mercury-intruded pores percolated through the samples, the effect of sample size on mercury intrusion became minor. The pore throat size of the artificial sandstone was used to estimate the air permeability using the relation proposed in the literature. The calculated air permeability of the smaller sandstone sample was higher. However, in principle, the air permeability of sandstone samples should be independent of the sample size. Two main conclusions can be drawn: (1) a fixed sample size should be used in MIP measurements or MIP simulation so that the PSD curves of different samples can be properly compared, (2) sample size needs to be considered when the pore throat size determined by MIP measurement is used for estimating air permeability.
Microarchitecture of the Augmented Bone Following Sinus Elevation with an Albumin Impregnated Demineralized Freeze-Dried Bone Allograft (BoneAlbumin) versus Anorganic Bovine Bone Mineral: A Randomized Prospective Clinical, Histomorphometric, and Micro-Computed Tomography Study
Authors: Márton Kivovics , Tamás Szabó , Orsolya Németh , Béla Czinkóczky , Ferenc Dőri , Péter Nagy , Csaba Dobó-Nagy , Lajos Csönge , Zsombor Lacza , Eitan Mijiritsky , György Szabó
Published: January 2018

Serum albumin has been identified as an endogenous protein that is integral to early bone regeneration. We hypothesized that albumin addition to allografts may result in better bone remodeling than what can be achieved with anorganic xenografts. Sinus elevations were performed at 32 sites of 18 patients with the lateral window technique. Sites either received filling with an anorganic bovine bone mineral (ABBM, BioOss, Geistlich, CH) or albumin impregnated allograft (BoneAlbumin, OrthoSera, AT). After 6-months patients received dental implants and 16 bone core biopsy samples were obtained from the ABBM filled, and 16 from the BoneAlbumin augmented sites. The biopsies were examined by histomorphometry and µCT. Percentage of the residual graft in the BoneAlbumin group was 0–12.7%, median 5.4% vs. ABBM 6.3–35.9%, median 16.9%, p < 0.05. Results of the µCT analysis showed that the microarchitecture of the augmented bone in the BoneAlbumin group resembles that of the native maxilla in morphometric parameters Trabecular Pattern Factor and Connectivity. Our data show that while ABBM successfully integrates into the newly formed bone tissue as persisting particles, BoneAlbumin is underway towards complete remodeling with new bone closely resembling that of the intact maxilla.
Green Synthesis of Three-Dimensional Hybrid N-Doped ORR Electro-Catalysts Derived from Apricot Sap
Authors: Karunagaran Ramesh , Coghlan Campbell , Shearer Cameron , Tran Diana , Gulati Karan , Tung Tran , Doonan Christian , Losic Dusan
Published: January 2018

Rapid depletion of fossil fuel and increased energy demand has initiated a need for an alternative energy source to cater for the growing energy demand. Fuel cells are an enabling technology for the conversion of sustainable energy carriers (e.g., renewable hydrogen or bio-gas) into electrical power and heat. However, the hazardous raw materials and complicated experimental procedures used to produce electro-catalysts for the oxygen reduction reaction (ORR) in fuel cells has been a concern for the effective implementation of these catalysts. Therefore, environmentally friendly and low-cost oxygen reduction electro-catalysts synthesised from natural products are considered as an attractive alternative to currently used synthetic materials involving hazardous chemicals and waste. Herein, we describe a unique integrated oxygen reduction three-dimensional composite catalyst containing both nitrogen-doped carbon fibers (N-CF) and carbon microspheres (N-CMS) synthesised from apricot sap from an apricot tree. The synthesis was carried out via three-step process, including apricot sap resin preparation, hydrothermal treatment, and pyrolysis with a nitrogen precursor. The nitrogen-doped electro-catalysts synthesised were characterised by SEM, TEM, XRD, Raman, and BET techniques followed by electro-chemical testing for ORR catalysis activity. The obtained catalyst material shows high catalytic activity for ORR in the basic medium by facilitating the reaction via a four-electron transfer mechanism.
Notions of Rough Neutrosophic Digraphs
Authors: Ishfaq Nabeela , Sayed Sidra , Akram Muhammad , Smarandache Florentin
Published: January 2018

Graph theory has numerous applications in various disciplines, including computer networks, neural networks, expert systems, cluster analysis, and image capturing. Rough neutrosophic set (NS) theory is a hybrid tool for handling uncertain information that exists in real life. In this research paper, we apply the concept of rough NS theory to graphs and present a new kind of graph structure, rough neutrosophic digraphs. We present certain operations, including lexicographic products, strong products, rejection and tensor products on rough neutrosophic digraphs. We investigate some of their properties. We also present an application of a rough neutrosophic digraph in decision-making.
Characterisation of Polyphenol-Containing Extracts from Stachys mucronata and Evaluation of Their Antiradical Activity
Authors: Grigorakis Spyros , Makris Dimitris
Published: January 2018

Background: The aromatic plant Stachys mucronata (Lamiaceae) is endemic to the island of Crete (southern Greece), but as opposed to other native Greek members of this family, this species has never been investigated in the past with regard to its polyphenolic composition and antioxidant potency. Methods: Aerial parts of S. mucronata were exhaustively extracted and partly fractionated through partition, using n-butanol and dichloromethane. Results: Following an initial examination, which consisted of estimating the total polyphenol content and the antiradical activity, the n-butanol extract was found to be by far the richest in polyphenols, exhibiting much stronger antiradical activity compared with the dichloromethane counterpart. On this basis, the n-butanol extract was analysed by liquid chromatography-diode array-mass spectrometry, to tentatively characterise the principal polyphenolic components, which were shown to be flavonol but mainly flavone derivatives. Conclusions: The most potent radical-scavenging compounds were detected in the n-butanol fraction of the extracts, suggesting that the most active antioxidants in S. mucronate are relatively polar. The analyses suggested the major constituents to be derivatives of the flavone luteolin, accompanied by apigenin analogues, as well as flavonol glycosides and chlorogenate conjugates.
Effect of Internal Stress of Incoming Strip on Hot Rolling Deformation Based on Finite Element and Infinite Element Coupling Method
Authors: Liu Chao , He Anrui , Qiang Yi , Guo Defu , Shao Jian
Published: January 2018

Limited by the deficiency of the finite element method (FEM) to deal with infinite domain problems, the traditional FEM rolling model is not suitable enough to study the effect of the complex internal stress of the incoming strip on hot rolling deformation. To solve this problem, the finite element and infinite element (FE-IE) coupling method is adopted, where the finite element is for the rolling area of the strip and the infinite element is for the elastic constraint of the strip end. Based on the improved rolls-strip coupling model, several internal stresses with typical distribution forms are applied to the strip by a programmed user subroutine, and the effect of the internal stress of the incoming strip on hot rolling deformation is evaluated. The results show that under the same average stress, the various distribution forms of internal stress have little effect on the total roll force, mainly because of the average effect. The uniform internal stress decreases the central thickness and quadratic crown of the strip. Under the symmetric stress and asymmetric stress, the thickness of each fiber along the strip width direction is closely related to the magnitude and distribution of the stress deviation (subtract the average stress from the longitudinal stress). Under the quadratic wave stress, the central thickness and quadratic crown vary almost linearly with the amplitude of the stress deviation. The efficiency coefficients obtained can be treated as a theoretical basis for the further development of an accurate prediction model of hot rolling.
Roller Burnishing of Particle Reinforced Aluminium Matrix Composites
Authors: Nestler Andreas , Schubert Andreas
Published: January 2018

Energy and resource efficient systems often demand the use of light-weight materials with a specific combination of properties. However, these requirements usually cannot be achieved with homogeneous materials. Consequently, composites enabling tailored properties gain more and more importance. A special kind of these materials is aluminium matrix composites (AMCs), which offer elevated strength and wear resistance in comparison to the matrix alloy. However, machining of these materials involves high tool wear and surface imperfections. An approach to producing high-quality surfaces consists in roller burnishing of AMCs. Furthermore, such forming technologies allow for the generation of strong compressive residual stresses. The investigations address the surface properties in the roller burnishing of AMCs by applying different contact forces and feeds. For the experiments, specimens of the alloy AA2124 reinforced with 25% volume proportion of SiC particles are used. Because of the high hardness of the ceramic particles, roller bodies were manufactured from cemented carbide. The results show that roller burnishing enables the generation of smooth surfaces with strong compressive residual stresses in the matrix alloy. The lowest surface roughness values are achieved with the smallest feed (0.05 mm) and the highest contact force (750 N) tested. Such surfaces are supposed to be beneficial for components exposed to dynamic loads.
Microstructural Evolution during Severe Plastic Deformation by Gradation Extrusion
Authors: Frint Philipp , Härtel Markus , Selbmann René , Dietrich Dagmar , Bergmann Markus , Lampke Thomas , Landgrebe Dirk , Wagner Martin
Published: January 2018

In this contribution, we study the microstructural evolution of an age-hardenable AA6082 aluminum alloy during severe plastic deformation by gradation extrusion. A novel die design allowing an interruption of processing and nondestructive billet removal was developed. A systematic study on the microstructure gradient at different points of a single billet could be performed with the help of this die. Distinct gradients were investigated using microhardness measurements and electron microscopy. Our results highlight that gradation extrusion is a powerful method to produce graded materials with partially ultrafine-grained microstructures. From the point of view of obtaining an ultrafine-grained surface layer with maximum hardness, only a small number of forming elements is needed. It was also found that large incremental deformation by too many forming elements may result in locally heterogeneous microstructures and failure near the billet surface caused by localization of deformation. Furthermore, considering economical aspects of processing, fewer forming elements are preferred since several processing parameter-related cost factors are then significantly lower.
Compensation of Hysteresis on Piezoelectric Actuators Based on Tripartite PI Model
Authors: An Dong , Li Haodong , Xu Ying , Zhang Lixiu
Published: January 2018

Piezoelectric ceramic actuators have been widely used in nanopositioning applications owing to their fast response, high stiffness, and ability to generate large forces. However, the existence of nonlinearities such as hysteresis can greatly deteriorate the accuracy of the manipulation, even causing instability of the whole system. In this article, we have explained the causes of hysteresis based on the micropolarization theory and proposed a piezoelectric ceramic deformation speed law. For this, we analyzed the piezoelectric ceramic actuator deformation speed law based on the domain wall theory. Based on this analysis, a three-stage Prandtl–Ishlinskii (PI) model (hereafter referred to as tripartite PI model) was designed and implemented. According to the piezoelectric ceramic deformation speed law, this model makes separate local PI models in different parts of piezoelectric ceramics’ hysteresis curve. The weighting values and threshold values of the tripartite PI model were obtained through a quadratic programming optimization algorithm. Compared to the classical PI model, the tripartite PI model can describe the asymmetry of hysteresis curves more accurately. A tripartite PI inverse controller, PI inverse controller, and Preisach inverse controller were used to compensate for the piezoelectric ceramic actuator in the experiment. The experimental results show that the inclusion of the PI inverse controller and the Preisach inverse controller improved the tracking performance of the tripartite PI inverse model by more than 80%.
Influence of Salinity and Pb on the Precipitation of Zn in a Model System
Authors: Tandon Kai , John Melanie , Heuss-Aßbichler Soraya , Schaller Valentin
Published: January 2018

Fly ash from solid waste incineration plants is a source of a significant mass flow of Zn- and Pb-containing waste. Acidic leaching removes most heavy metals from fly ash, but leads to high concentrations of soluble salts in the solution, resulting in a saline solution enriched in heavy metals. Common treatment methods cause voluminous sludge that is mostly disposed of as hazardous waste and hence leads to a loss of Zn and other heavy metals. On a laboratory scale, precipitation experiments with 2000 mg/L Zn were performed to investigate the impact of salinity (0 to >70,000 mg/L Cl, 0 to 5400 mg/L SO4) and Pb concentration (0 to 800 mg/L) on the formation of mineral phases. The removal efficiency of Zn and Pb after alkalization of the solution was studied. Characterization of the precipitates showed that salinity has a significant impact on the phases produced. At a low salt concentration, zincite (ZnO) is formed. With increasing salinity, the higher concentration of chloride and sulfate increases the stability of various Zn sulphate hydroxides. At a medium salinity of 7000 mg/L, bechererite is predominantly formed, whereas a higher salinity leads to the formation of gordaite. Addition of low amounts of Pb enlarges the stability field of zincite to medium saline solutions but causes lower removal efficiency. The lower removal efficiency observed at low salinity increases at a higher salinity. In high saline solutions, high Pb concentrations (800 mg/L) are needed to form laurionite, a Pb-hydroxychloride phase.