bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of the Ortachala HPP low head dam abutment deformation and seepage regime
Authors: Kalabegishvili Mirian , Klimiashvili Levan , Gurgenidze David , Ujma Adam
Published: June 2019

During Ortachala HPP operation period cracks were formed in the right-bank of foundation, where is located underground fish-way sections. Right bank dam-foundation contact opened only in the horizontal direction, that caused 5.5 cm gap development, while there were no changes in the vertical direction. Visual researches showed that cracks (size is 4–5 cm) developed in fish-way construction. Mathematical models: fish-drainage-foundation, retaining wall-drainage-foundation, with the use of the finite element scheme, allowed us to finalize the suffusion-deformation process developed during the operation, namely: in the cracking zones of fish-way developed high gradients of seepage pressure, causing suffusion; under the influence of the weight of the soil and transport, shrinkage of the soil developed, which for the foundation of the right bank, created bending deformations causing the rotation of the soil in the vertical plane; bending deformation of the foundation at the contact of the concrete structure and the embankment caused a horizontal opening, spread out – at a depth of 4m. In connection with this, the retaining wall, leaning against the ground, loses support and, under the influence of hydrostatic pressure, tensile stress develops in it. In the case of crack formation in the wall, concentrated seepage will develop, which will cause groundwater rise in the main road and various unfavourable processes. Having established the reason for opening the contact, the fish was closed, as a result of which above mentioned process was stopped. Thus, the waterproofing of the fish-way is a necessary measure for the normal operation of the waterworks.
The occurrence of antibiotic-resistant bacteria, including Escherichia coli, in municipal wastewater and river water
Authors: Osińska Adriana , Korzeniewska Ewa , Harnisz Monika , Niestępski Sebastian , Jachimowicz Piotr
Published: June 2019

Wastewater treatment plants (WWTPs) are major reservoirs of antibiotic-resistant bacteria (ARB) which are transported to the natural environment with discharged effluents. Samples of untreated wastewater (UWW) and treated wastewater (TWW) from four municipal WWTPs and samples of river water collected upstream (URW) and downstream (DRW) from the effluent discharge point were analyzed in the study. The total counts of bacteria resistant to β-lactams and tetracyclines and the counts of antibiotic-resistant Escherichia coli were determined. Antibiotic-resistant bacteria, including antibiotic-resistant E. coli, were removed with up to 99.9% efficiency in the evaluated WWTPs. Despite the above, ARB counts in TWW samples were high at up to 1.25x105 CFU/mL in winter and 1.25x103 CFU/mL in summer. Antibiotic-resistant bacteria were also abundant (up to 103 CFU/ml) in URW and DRW samples collected in winter and summer. In both UWW and TWW samples, the counts of ARB and antibiotic-resistant E. coli were at least one order of magnitude lower in summer than in winter. The study revealed that despite the high efficiency of bacterial removal in the wastewater treatment processes, considerable amounts of ARB are released into the environment with TWW and that the percentage of ARB in total bacterial counts increases after wastewater treatment.
Assessment of the impact of the traffic situation in urban area on the amount of volatile organic compounds getting into the cabin of the car on the road
Authors: Skrętowicz Maria , Świeściak Joanna
Published: June 2019

In the paper the levels of concentrations of volatile organic compounds getting into car cabin during the driving have been measured. Three series of the tests have been performed. Each series has been carried out in different road situation in terms of traffic intensity. For the tests exploited passenger car, Subaru Impreza was used. Before every series the background measurements was carried out and directly after that, the correct the correct tests were performed. Inside the cabin 14 different organic compounds have been identified. To analyse the change of the concentrations levels between the correct and background test have been calculated. The results indicate that the longer time of travel caused that the driver and passengers are more exposed to highest concentrations of VOCs.
Artificial neural network (ANN) approach for modeling of selected biogenic compounds in a mixture of treated municipal and dairy wastewater
Authors: Struk-Sokołowska Joanna , Ofman Piotr , Demirel Sevgi
Published: June 2019

This paper presents artificial neural network (ANN) model of wastewater treatment plant, which was used for average monthly concentrations of N-NH4+, N-NO3-, N-NO2-, total Kiejdahl nitrogen (TKN), PO43-and SO42-approximation. ANN model was developed for wastewater treatment plant located in Bystre, Poland which treats municipal wastewater with a share of dairy wastewater. The object was chosen because of the unique location, in the Great Mazury Lakes area and the need for its special environmental protection. Input layer of developed ANN model consisted of BOD, COD, concentrations of total nitrogen and total phosphorus, total organic carbon, sulphates, wastewater temperature and pH., The developed model reflected extreme values observed during study period. Average error percentage with which output variables were approximated equalled to 35.35%; 8.99%; 21.23%; 5.08%; 10.99%; 3.02% respectively for N-NH4+, N-NO3-, N-NO2-, TKN, PO43-and SO42-.
Electronic nose – an instrument for odour nuisances monitoring
Authors: Szulczyński Bartosz , Gębicki Jacek
Published: June 2019

An increasingly frequent problem of people living in urban agglomerations is the occurrence of odour nuisance. Although the source of these nuisances is different, their common feature is that they are a complex mixture of odour compounds with different odour thresholds. However, from a practical point of view, the most valuable would be a direct link between the odour intensity and the results of on-line analytical air monitoring. Such a possibility is created by the use of electronic noses (devices that are supposed to imitate the human sense of smell) to measure odours. The paper presents the use of an electronic nose combined with multiple liear regression model (MLR) to determine the odour intensity of the two-component mixture samples of commonly known odour compounds: trimethylamine (TMA) and triethylamine (TEA) in concentration range 50–200 ppm v/v. The obtained results were compared with the theoretical values determined using Zwaardemaker and euclidean additivity (EA) models. For high concentrations of substances in the mixtures (> 150 ppm v/v), the masking effect was observed.
Thermomodernization of buildings with the utilization of green walls
Authors: Wesołowska Małgorzata , Laska Marta
Published: June 2019

The revitalization of historical buildings is a subject that is increasingly being discussed around the world. This is connected with the goal set by the European and thus Polish and local policy to reduce energy consumption in existing buildings. The publication presents an unconventional solution for thermal modernization of buildings with the utilization of green walls. The article presents the literature and legal acts review on green walls, their construction and impact on existing buildings. It describes the benefits and disadvantages resulting from the use of vegetation on the external walls. Additionally the possibility of using green walls at the historic facility located in Wroclaw (Poland) is presented.
Concept of reducing harmful emissions by road transport vehicles in the tourist route Karpacz– Jelenia Góra
Authors: Zajac Pawel , Haladyn Szymon , Kwasniowski Stanislaw
Published: June 2019

The research carried out by the "Logistics” Students' Scientific Circle functioning at the Faculty of Mechanical Engineering of the Wrocław University of Technology shows that every day, between the communes which cross railway lines 308 and 340, 1911 persons move in circular migrations solely due to occupational activity. Some of them could travel by rail. Eliminating 500 cars a day (i.e. 250 outwards and return travels on the route Kowary/Karpacz–Jelenia Góra) would reduce annual carbon dioxide emissions by approximately 460 tonnes. Further reductions in CO2 emissions in transport can be achieved thanks to the use of railways by tourists, of which - in the area of the communes of Karpacz, Kowary and Mysłakowice, i.e. an area of outstanding recreational valors - there was over 300,000 in 2016 [3]. Rational train running interval was determined and a timetable proposed, taking into account routes leading beyond Jelenia Góra. The paper justifies the need for the introduction of complementary communication provided by electrobuses. The concept of reactivating traffic in this area should be complemented by the construction of a Park&Ride car park. The possibility of further development of the transport system in the area in question was also proposed.
New developments of Chinese interpretation of Ferdinand de Saussure’s linguistic thought
Authors: Romagnoli Chiara
Published: June 2019

The introduction of Saussure’s linguistic ideas in China began in the thirties thanks to scholars such as such as Wang Li, Gao Mingkai, Fang Guangtao and Chen Wangdao. They were the first to disseminate and apply to the analysis of their language the constructs included in the Cours de linguistique générale. Masini (1985) has thoroughly investigated this issue, pointing out how troubled the first phase of Saussurean studies in China was. Completed in the 1960s but published only in 1980, the first translation of the Cours made by Gao Mingkai marked a new beginning of Saussurean studies in China, as confirmed not only by the debate raised by the reading of this work but also by the translations of other sources which have made the portrait of the Swiss linguist more accurate (Péi 2003; Zhào 2005; Mǎ 2008; Romagnoli 2007; 2012). Three Chinese translations of the Cours, several monographs on Saussure, hundreds of academic papers are now available to Chinese readers, whose linguistics knowledge and linguistic background have also changed compared to the first decades of the last century. The aim of this paper is to illustrate the most recent development of the debate regarding Saussurean linguistics in China. In order to do so, two issues are taken into account: the critical stances expressed by Chinese scholars toward the interpretation of the ideas of the Swiss linguist in China and the latest development of the debate on Saussurean semiology.
The introduction of English grammar studies into China in the 19thcentury
Authors: Pellin Tommaso
Published: June 2019

During the first half of the 19th century, Protestant missionaries based in China started teaching some English to the students attending their schools; in the second half of the century Chinese scholars opened their own language schools and wrote their grammarbooks of English.

This contribution describes four of the grammarbooks for English that marked milestones in that period: Morrison’sA Grammar of the English Language(1823), Lobscheid’sChinese-English grammar(1864), Cáo Xiāng’sYīngzìrùmén(1874), and Wāng Fèngzǎo’sYīngwén jǔyú(1878). Its aim is to sketch the lines of the introduction of some of the key terms for grammar, within the theoretical framework of the phenomenon of grammatization of Chinese: the mutual influence from contemporary grammatical studies of Chinese and other languages will be highlighted.
Langage intérieur et origine de la conscience : le cas de Tran Duc Thao
Authors: D’Alonzo Jacopo
Published: June 2019

Bien que le langage intérieur soit une donnée fondamentale de la vie de l’esprit et malgré le fait que la recherche expérimentale sur le langage intérieur et ses fonctions devienne de plus en plus sophistiquée, la philosophie de l’esprit a rarement pris au sérieux le caractère langagier de la conscience et, dans le débat philosophique le plus récent sur le « mind-body problem » et le « hard problem of consciousness », la référence au langage, et en particulier au langage intérieur, n’est pas mobilisée sauf sous la forme du « language of thought ». Toutefois, l’étude philosophique d’un tel phénomène pourrait permettre de surmonter les limites des deux options qui se partagent le champ théorique, à savoir le physicalisme et le dualisme, et ainsi d’expliquer dialectiquement les spécificités de la cognition humaine. Dans les pages qui suivent, nous examinerons le cas de la réflexion philosophique de Tran Duc Thao (1917-1993) sur le langage intérieur dans sesRecherches sur l’origine du langage et de la conscience(1973), où l’auteur reconnait au langage et à son intériorisation un rôle central dans la formation de la conscience.
A proposed radiological classification system of Hoffa’s fracture based on fracture configuration and consequent optimal treatment strategy along with the review of literature
Authors: Bagaria Vaibhav , Sharma Gaurav , Waghchoure Chaitanya , Chandak Rajendra M , Nemade Amit , Tadepelli Kalyan , Pawar Prashant
Published: June 2019

Background: Coronal fractures of distal end femur, referred as Hoffa’s fracture are not uncommon, yet easily missed injuries lacking proper classification system and consensus for ideal treatment. While most trauma surgeons adopt different strategies based on the fracture configuration and their own experience, there are no set ways to classify these based on the most appropriate treatment strategy. Methods: Thirty cases of Hoffa fracture from tertiary care centres were studied for the fracture pattern, fragment size, comminution and possible variations to formulate a radiological classification and treatment guidelines. Additionally, a literature search was used to analyze 77 case studies based on Hoffa fracture to find out the common fracture patterns and treatment modalities adopted for varying fracture patterns in these studies. Six independent observers participated in testing the inter-observer reliability of the proposed classification. Results: A new proposed radiological classification for Hoffa fracture consists of four main types. Type 1 is with fracture fragment >2.5 cm, Type 2 with fragment <2.5 cm, Type 3 is comminuted fracture, Type 4 are subdivided as Type 4a – Anterior, Type 4b – Bicondylar, Type 4c – Osteochondral type and Type 4d – With supracondylar extension. Optimum treatment modality depends on the type of Hoffa’s fracture and has been suggested in the study. Interobserver reliability demonstrated that overall agreement was 0.907692 with a fixed marginal Kappa of 0.881067 and free Marginal Kappa at 0.892308. Intra-observer reliability test for the classification system showed a strong Kappa value of +1.0. Conclusion: The new suggested classification helps identify different types of Hoffa’s fracture. This is likely to help decide optimal surgical treatment depending on the nature of the injury. The classification system has high inter and intra-observer reliability that enables its universal applicability.
Kp forecasting with a recurrent neural network
Authors: Sexton Ernest Scott , Nykyri Katariina , Ma Xuanye
Published: June 2019

In an effort to forecast the planetary Kp-index beyond the current 1-hour and 4-hour predictions, a recurrent neural network is trained on three decades of historical data from NASA’s Omni virtual observatory and forecasts Kp with a prediction horizon of up to 24 h. Using Matlab’s neural network toolbox, the multilayer perceptron model is trained on inputs comprised of Kp for a given time step as well as from different sets of the following six solar wind parameters, Bz, n, V, |B|, σB and $ {\sigma }_{{B}_z}$. The purpose of this study was to test which combination of the solar wind and Interplanetary Magnetic Field (IMF) parameters used for training gives the best performance as defined by correlation coefficient, C, between the predicted and actually measured Kp values and Root Mean Square Error (RMSE). The model consists of an input layer, a single nonlinear hidden layer with 28 neurons, and a linear output layer that predicts Kp up to 24 h in advance. For 24 h prediction, the network trained on Bz, n, V, |B|, σB performs the best giving C in the range from 0.8189 (for 31 predictions) to 0.8211 (for 9 months of predictions), with the smallest RMSE.
Laparoscopic Approach in Surgical Staging of Endometrial Cancer
Authors: Mouraz Mariana , Ferreira Cátia Sofia , Gonçalves Sónia , Martins Nuno Nogueira , Martins Francisco Nogueira
Published: June 2019

Objective To compare laparoscopy with laparotomy for surgical staging of endometrial cancer.

Methods A cohort of women with preoperative diagnosis of endometrial cancer who underwent surgical staging was retrospectively evaluated. The main study end points were: morbidity and mortality, hospital length of stay, perioperative adverse events and recurrence rate. Data analysis was performed with the software SPSS v25 (IBM Corp., Armonk, NY, USA), categorical variables using a Chi-square and Fisher test, and continuous variables using the Student t-test.

Results A total of 162 patients were analyzed. One-hundred and thirty eight patients met the inclusion criteria, 41 of whom underwent staging by laparoscopy and 97 by laparotomy. Conversions from laparoscopy to laparotomy happened in 2 patients (4.9%) and were secondary to technical difficulties and poor exposure. Laparoscopy had fewer postoperative adverse events when compared with laparotomy (7.3% vs 23.7%, respectively; p = 0.005), but similar rates of intraoperative complications, despite having a significantly longer operative time (median, 175 vs 130 minutes, respectively; p < 0.001). Hospital stay was significantly lower in laparoscopy versus laparotomy patients (median, 3 vs 7 days, respectively; p < 0.001). No difference in recurrence or mortality rates were observed.

Conclusion Laparoscopic surgical staging for endometrial cancer is feasible and safe. Patients have lower postoperative complication rates and shorter hospital stays when compared with the approach by laparotomy.
Knowledge of Pregnant Adolescents about Human Papillomavirus
Authors: Tanaka Erika Zambrano , Kamizaki Sílvia Souza , Quintana Silvana Maria , Pacagnella Rodolfo de Carvalho , Surita Fernanda Garanhani
Published: June 2019

Objective To evaluate the level of information possessed by pregnant adolescents regarding the human papillomavirus (HPV).

Methods Descriptive study developed in the adolescent prenatal outpatient clinic of a tertiary hospital from the state of São Paulo, Brazil. Data were collected between June and December 2017 following approval from the ethics and research committee (CAAE: 1.887.892/2017). Pregnant adolescents, ≤18 years old, who attended the abovementioned outpatient section, composed the sample. Those diagnosed with a psychiatric disorder and those with hearing or cognitive disabilities were excluded. After acceptance to participate in the present study, the pregnant adolescents signed an Informed Consent Form. Regarding the statistical analysis, the chi-squared test and the Fisher exact test were used.

Results Regarding the knowledge about HPV, 123 (80.92%) of the participants had already heard about the subject; for 77 (50.66%), their schools had been the source of the information; 101 (66.45%) did not know how they could be infected by the virus. Age variation did not influence their knowledge on how to prevent themselves from HPV (p = 0.2562). The variable vaccine is associated with HPV prevention (p < 0.0001).

Conclusion The pregnant adolescents composing the sample have shown to have knowledge about HPV. However, they do not prevent themselves from it appropriately, given that little more than half of the sample was vaccinated, had not reported an understanding that the use of preservatives and vaccination are effective means of prevention, and did not correlate HPV with uterine cervical cancer.
On the concept and theory of induced drag for viscous and incompressible steady flow
Authors: Zou Shu-Fan , Wu J. Z. , Gao An-Kang , Liu Luoqin , Kang Linlin , Shi Yipeng
Published: June 2019

For steady flow, one usually decomposes the total drag into different components by wake-plane integrals and seeks their reduction strategies separately. Unlike the body-surface stress integral, the induced drag as well as the profile drag has been found to depend on the streamwise location of the wake plane used for drag estimate. It gradually diminishes as the wake plane moves downstream, which was often attributed to numerical dissipation. In this paper, we present an exact general force-breakdown theory and its numerical demonstrations for viscous incompressible flow over an arbitrary aircraft to address this puzzling issue. Based on the theory, the induced and profile drags do depend inherently on the wake-plane location rather than being merely caused by numerical dissipation. The underlying mechanisms are identified in terms of the components, moments, and physical dissipation of the Lamb-vector field produced by the aircraft motion. This theoretical prediction is fully consistent with the linear far-field force theory that the induced drag finally vanishes and the profile drag increases to the total drag at an infinitely far field for viscous flow. Moreover, as a product of this exact theory, a new compact midwake approximation for the induced drag is proposed for the convenience of routine wake survey in industry. Its prediction is similar to conventional formulas for attached flow but behaves much better for separated flow.
Effects of phase delay on synchronization in a nonlinear micromechanical oscillator
Authors: Huan Ronghua , Pu Dong , Wang Xuefeng , Wei Xueyong
Published: June 2019

Phase feedback is commonly utilized to set up a MEMS oscillator. In most studies, the phase delay is fixed on π/2 for a maximum oscillation amplitude. In this letter, we study the dynamics of synchronization in a nonlinear micromechanical oscillator operating on different phase delays. The analytical and experimental results show that the synchronization region shifts and the size of this region varies depending on the phase delay. The frequency stability of the self-sustained oscillator holds the best in the case of phase delay equal to π/2 and can be further improved to the same level after synchronization. Our work reveals the effects of phase delay on synchronization and presents an easy-to-implement strategy for tuning the synchronization by controlling the phase delay of the oscillation feedback circuit in a nonlinear micromechanical oscillator.
State variables for glasses: The case of amorphous ice
Authors: Giovambattista Nicolas , Starr Francis W. , Poole Peter H.
Published: June 2019

Glasses are out-of-equilibrium systems whose state cannot be uniquely defined by the usual set of equilibrium state variables. Here, we seek to identify an expanded set of variables that uniquely define the state of a glass. The potential energy landscape (PEL) formalism is a useful approach within statistical mechanics to describe supercooled liquids and glasses. We use the PEL formalism and computer simulations to study the transformations between low-density amorphous ice (LDA) and high-density amorphous ice (HDA). We employ the ST2 water model, which exhibits an abrupt first-order-like phase transition from LDA to HDA, similar to that observed in experiments. We prepare a number of distinct samples of both LDA and HDA that have completely different preparation histories. We then study the evolution of these LDA and HDA samples during compression and decompression at temperatures sufficiently low that annealing is absent and also during heating. We find that the evolution of each glass sample, during compression/decompression or heating, is uniquely determined by six macroscopic properties of the initial glass sample. These six quantities consist of three conventional thermodynamic state variables, the number of molecules N, the system volume V, and the temperature T, as well as three properties of the PEL, the inherent structure (IS) energy EIS, the IS pressure PIS, and the average curvature of the PEL at the IS SIS. In other words, (N,V,T,EIS,PIS,SIS) are state variables that define the glass state in the case of amorphous ice. An interpretation of our results in terms of the PEL formalism is provided. Since the behavior of water in the glassy state is more complex than for most substances, our results suggest that these six state variables may be applicable to amorphous solids in general and that there may be situations in which fewer than six variables would be sufficient to define the state of a glass.
Interactive molecular dynamics in virtual reality from quantum chemistry to drug binding: An open-source multi-person framework
Authors: O’Connor Michael B. , Bennie Simon J. , Deeks Helen M. , Jamieson-Binnie Alexander , Jones Alex J. , Shannon Robin J. , Walters Rebecca , Mitchell Thomas J. , Mulholland Adrian J. , Glowacki David R.
Published: June 2019

As molecular scientists have made progress in their ability to engineer nanoscale molecular structure, we face new challenges in our ability to engineer molecular dynamics (MD) and flexibility. Dynamics at the molecular scale differs from the familiar mechanics of everyday objects because it involves a complicated, highly correlated, and three-dimensional many-body dynamical choreography which is often nonintuitive even for highly trained researchers. We recently described how interactive molecular dynamics in virtual reality (iMD-VR) can help to meet this challenge, enabling researchers to manipulate real-time MD simulations of flexible structures in 3D. In this article, we outline various efforts to extend immersive technologies to the molecular sciences, and we introduce “Narupa,” a flexible, open-source, multiperson iMD-VR software framework which enables groups of researchers to simultaneously cohabit real-time simulation environments to interactively visualize and manipulate the dynamics of molecular structures with atomic-level precision. We outline several application domains where iMD-VR is facilitating research, communication, and creative approaches within the molecular sciences, including training machines to learn potential energy functions, biomolecular conformational sampling, protein-ligand binding, reaction discovery using “on-the-fly” quantum chemistry, and transport dynamics in materials. We touch on iMD-VR’s various cognitive and perceptual affordances and outline how these provide research insight for molecular systems. By synergistically combining human spatial reasoning and design insight with computational automation, technologies such as iMD-VR have the potential to improve our ability to understand, engineer, and communicate microscopic dynamical behavior, offering the potential to usher in a new paradigm for engineering molecules and nano-architectures.
Supercontinuum vector beam generation by independent manipulations of angular polarization and geometric phase
Authors: Wakayama Toshitaka , Shinozaki Natsumi , Shoji Misaki , Ishiyama Takayuki , Sakaue Kazuyuki , Miura Taisuke , Ejima Takeo , Higashiguchi Takeshi
Published: June 2019

We propose and demonstrate production of a supercontinuum vector beam by independent manipulations of an angular polarization and a geometric phase. The proposed concept consists of left- and right-hand vortex phase cancelation. Two-dimensional distributions of the angular polarization and the geometric phase in the generated vector beam are evaluated for a rigorous polarization analysis. Their azimuthal angles are linearly changed with matching ratios of more than 90%, as compared to the theoretical calculations. The geometric phase obtained from ellipsometric parameters is also shaped to be a uniform phase at an average of 0.10 rad and to angularly decrease the vortex phase up to −6.73 rad, respectively. Our strategy is sufficient for finding numerous applications, such as super-resolution microscopy, plasmonics, and spectroscopy.
Ultraviolet Fabry-Perot cavity with stable finesse under ultrahigh vacuum conditions
Authors: Schmitz Jonas , Meyer Hendrik M. , Köhl Michael
Published: June 2019

We have constructed an apparatus containing a linear ion trap and a high-finesse optical cavity in the ultraviolet spectral range. In our construction, we have avoided all organic materials inside the ultrahigh vacuum chamber. We show that, unlike previously reported, the optical cavity does not degrade in performance over a time scale of 9 months.
Strategies and challenges of high-pressure methods applied to thermoelectric materials
Authors: Morozova Natalia V. , Korobeinikov Igor V. , Ovsyannikov Sergey V.
Published: June 2019

We describe the current state of experimental studies of the effects of applied high pressure or stress on the thermoelectric properties and performance parameters of thermoelectric materials, as well as the challenges faced in this area and possible directions for future work. We summarize and analyze literature data on the effects of high pressure on the Seebeck coefficient (thermoelectric power) of different materials that are related to common families of thermoelectrics, such as Bi2Te3, Sb2Te3, Bi2Se3, PbTe, PbSe, SnTe, SnSe, Mg2Si, CoSb3, Si–Ge, and others, or that show promise as potential high-pressure thermoelectrics, such as ZrSe3 and Sn2P2Se6, and others. We consider how applied high pressure or stress can tune the performance parameters of thermoelectric materials through variations in their Seebeck coefficients and in their electrical and thermal conductivities. We point out the potential use of magnetic fields to generate significant transverse and longitudinal magneto-thermoelectric effects in thermoelectric materials, thereby affecting their performance parameters. We propose simple models of high-pressure thermoelectric converters whose performance parameters can be optimized by varying the pressure applied to their elements. We also discuss other possible ways in which high-pressure effects could be implemented in practical appliances.
Imaging of triboelectric charge distribution induced in polyimide film by using optical second-harmonic generation: Electronic charge distribution and dipole alignment
Authors: Taguchi Dai , Manaka Takaaki , Iwamoto Mitsumasa
Published: June 2019

By using an optical second-harmonic generation (SHG) microscope, we visualized spatial distribution of triboelectric charge in polyimide films, which are negatively charged by rubbing with a cotton belt. The origins of this triboelectric charging were excessive electronic charges and aligned dipoles. The excessive electronic charges were imaged using the probe laser wavelength of 1140 nm (SHG wavelength 570 nm), whereas the aligned dipoles were visualized by choosing the laser wavelength of 570 nm (SHG wavelength 285 nm). Combining the two visualized images showed that the dipolar alignment region with a width of 10 μm was induced on the rubbed polyimide surface, and at the same time, excess electronic charges were generated in that region. We conclude that dipolar alignment and electronic charging are main contributors, and the interaction between the two contributors plays an essential role in triboelectrification.
Intrinsic shape of free carrier absorption spectra in 4H-SiC
Authors: Grivickas P. , Redeckas K. , Gulbinas K. , Conway A. M. , Voss L. F. , Bora M. , Sampayan S. , Vengris M. , Grivickas V.
Published: June 2019

Free carrier absorption spectra are measured along the different polarization directions with respect to the c-axis of 4H-SiC using ultrafast differential transmission spectroscopy. Probing of excited carrier spectra in an undoped material reveals intrinsic resonances within the conduction band. Widths of the detected resonance peaks are shown to be wider than their theoretical estimates and more comparable to the ones observed in a low doped material. Relative strength of the peaks, on the other hand, is shown to be nearly excitation independent in contrast to the doping induced absorption weakening for the same transitions in n-type samples. Free carrier cross sections are extracted from the excitation dependency of the detected spectra and linked to the individual electron and hole contributions in the near infrared range.
Atomic-resolution in-situ cooling study of oxygen vacancy ordering in La0.5Sr0.5CoO3−δ thin films
Authors: Rui Xue , Klie Robert F.
Published: June 2019

The presence and potential ordering of oxygen vacancies play an important role in determining the electronic, ionic, and thermal transport properties of many transition metal oxide materials. Controlling the concentration of oxygen vacancies, as well as the structures of ordered oxygen vacancy domains, has been the subject of many experimental and theoretical studies. In epitaxial thin films, the concentration of oxygen vacancies and the type of ordering depend on the structure of the substrate as well as the lattice mismatch between the thin films and the substrate. However, the role of temperature or structural phase transitions in either the substrate or the epitaxial thin films in the oxygen vacancy ordering has remained largely unexplored. In particular, atomic-resolution imaging and spectroscopy analysis of oxygen vacancy ordering in thin films at temperatures below 300 K have not yet been reported. Here, we use aberration-corrected scanning transmission electron microscopy combined with in-situ cooling experiments to characterize the atomic/electronic structures of oxygen-deficient La0.5Sr0.5CoO3−δ thin films grown on SrTiO3 across its antiferrodistortive phase transition at 105 K. We demonstrate that atomic-resolution imaging and electron energy-loss spectroscopy can be used to examine variations in the local density of states as a function of sample temperature.
Ultra-low-temperature process effects on microscale abrasion of tool steel AISI D2
Authors: Gobbi Silvio José , Gobbi Vagner João , Reinke Gustavo , Muterlle Palloma Vieira , Rosa Daniel Monteiro
Published: June 2019

Ultra-low-temperature process treatments could raise tool steel wear resistance through microstructural change that occurs on the material, enhancing, that way, tools and dies lifetime. To investigate the tool steel wear resistance impact, micro-abrasive wear tests were carried out and an analysis based on the Archard's law was considered, evaluating specimen mass loss by laser interferometry. Micro-hardness, X-ray diffractometry, scanning and optical microscopy and carbides quantitative evaluation were carried out aiming to material characterisation. Results demonstrated a micro-hardness improvement, ranging from 0.9–4.7% for the cryogenically treated specimens, when compared to the bulk material. This effect is related, mainly, to the retained austenite transformation and to the increase of fine secondary carbides dispersed amount in the martensitic matrixes cryogenically treated.
Intercritical annealing pre-treatment used in a hot-dip galvanised TRIP steel
Authors: Li Yan , Ding Wei , Wang Baofeng
Published: June 2019

An intercritical annealing pre-treatment was added before the conventional two-step heat treatment process, and the effect of the isothermal bainitic transformation (IBT) time on the steel's microstructure and mechanical properties were investigated. The microstructure was investigated using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction, while the mechanical properties were evaluated using tensile testing. The microstructure of the three-step hot-dip galvanised transformation induced plasticity (TRIP) steel consists of ferrite, bainite, retained austenite, and martensite. The mechanical properties of the steel after the three-step heat treatment process are excellent, with a tensile strength above 770 MPa and elongation above 29%. The effect of IBT time on the mechanical properties was insignificant because the intercritical annealing pre-treatment increases the bainitic transformation rate.
Into the ordinary: non-elite actors and the mobility of harm reduction policies
Authors: Baker Tom , McCann Eugene , Temenos Cristina
Published: June 2019

Research on policy transfer and policy mobility has focused much attention on relatively elite actors, such as politicians, international organisations, think tanks, philanthropic donors, and consultancy firms. In contrast, this article uses the case of ‘harm reduction’ drug policy, an area of practice and research that is committed to valuing ‘non-elite’ actors, to show how they are frequently involved in mobilizing policy knowledge. Focusing on the role of service providers, activists and service users in the mobilization of harm reduction models, the paper discusses four key practices associated with these non-elite actors: cooperation, convergence, disobedience and display. The article argues that the deep involvement of relatively non-elite actors in mobilizing harm reduction policies means that multi-disciplinary scholarship would be enriched by going ‘into the ordinary’ in a wide range of policy contexts.
Are wicked problems really so wicked? Perceptions of policy problems
Authors: Peters B Guy , Tarpey Matthew
Published: June 2019

The concept of wicked problems has become widely used in policy analysis. The popularity of the concept has led to its overuse, and has produced significant conceptual stretching. This paper investigates the extent to which this stretching has led to the application of the concept to issues which are not ‘wicked’ in any meaningful sense. Based on a survey of policy experts, we find that few, if any, policy problems are perceived to have all the attributes of wicked problems. Although the concept does not appear useful in categorizing problems in a strict manner, the presence or absence of certain attributes can still be used in understanding the problems and in designing solutions for them.
Iron self diffusion in liquid pure iron and iron-carbon alloys
Authors: Meyer A , Hennig L , Kargl F , Unruh T
Published: June 2019

With incoherent quasielastic neutron scattering self-diffusion coefficients

in pure iron, and iron-carbon alloys containing 8.7 at% and 16.9 at% carbon have been measured. At the melting point

in liquid iron is

m2 s−1. For the close-to-eutectic Fe83.1C16.9 composition

m2 s−1 at T

K. Contradicting conclusions drawn from literature values of tracer diffusion experiments the addition of carbon has only a minor effect on the iron mobility: at a given temperature the self-diffusion coefficient in Fe83.1C16.9 is only 10% larger than in liquid iron, although mixing has a drastic effect on liquidus temperature and phase behavior.
Microplasticity and yielding in crystals with heterogeneous dislocation distribution
Authors: Zhang Xu , Xiong Jian , Fan Haidong , Zaiser Michael
Published: June 2019

In this study, we use discrete dislocation dynamics simulation to investigate the effect of heterogeneous dislocation density on the transition between quasi-elastic deformation and plastic flow in face-centered cubic single crystals. By analyzing the stress–strain curves of samples with an initial, axial dislocation density gradient, we arrive at the following conclusions: (i) in the regime of quasi-elastic deformation before the onset of plastic flow, the effective elastic modulus of the simulated samples falls significantly below the value for a dislocation-free crystal. This modulus reduction increases with decreasing dislocation density gradient: crystals with homogeneous dislocation distribution are thus weakest in the quasi-elastic regime; (ii) the transition towards plastic flow occurs first in regions of reduced dislocation density. Therefore, the overall yield stress decreases with increasing dislocation density gradient; (iii) crystals with dislocation density gradient exhibit a more pronounced hardening stage during which stress is re-distributed onto stronger regions with higher dislocation density until the sample flows at a constant flow stress that is approximately independent of dislocation density gradient. We interpret these findings in terms of a continuum dislocation dynamics inspired model of dislocation density evolution that accounts for geometrically reversible (‘inversive’) dislocation motions. The transition between quasi-elastic and plastic deformation is interpreted as a transition from inversive to non-inversive dislocation motion, and the initial differences in elastic modulus are related to a density dependent polarizability of the dislocation system. The subsequent plastic flow behavior is analyzed in terms of a modified version of Mughrabi’s composite model.
A finite element method for the determination of the relative response of ionization chambers in MR-linacs: simulation and experimental validation up to 1.5 T
Authors: Pojtinger Stefan , Kapsch Ralf-Peter , Dohm Oliver Steffen , Thorwarth Daniela
Published: June 2019

In magnetic resonance (MR) guided radiotherapy, the magnetic field-dependent change in the dose response of ionization chambers is typically included by means of a correction factor

. This factor can be determined experimentally or calculated by means of Monte Carlo (MC) simulations. To date, a small number of experimental values for

at magnetic flux densities above 1.2 T have been available to benchmark these simulations. Furthermore, MC simulations of the dose response of ionization chambers in magnetic fields (where such simulations are based on manufacturer blueprints) have been shown to converge with results that deviate considerably from experimental values for orientations where the magnetic field is perpendicular to the axis of the ionization chamber and the influence of the magnetic field is largest.

In this work,

was simulated for a PTW 30013 Farmer ionization chamber using an approach based on finite element simulations. First, the electrical field inside the ionization chamber was simulated using finite element methods. The collecting volume of the ionization was not defined in terms of the physical dimensions of the detector but in terms of the simulated electrical field lines inside the chamber. Then, an MC simulation of the dose response of a Farmer type chamber (PTW 30013) was performed using EGSnrc with a dedicated package to consider the effect of the magnetic field. In the second part,

was determined experimentally for two different PTW 30013 ionization chambers for a range of magnetic flux densities between B  =  0 and 1.5 T, covering the range of commercially available MR-linacs.

In the perpendicular orientation, the maximum difference between the simulated values for

and the experimental values for

was 0.31(30)% and the minimum difference was 0.02(24)%. For the PTW 30013 ionization chambers, the experimental values for

were 0.9679(1) and 0.9681(1) for a magnetic flux density of 1.5 T. The value resulting from the simulation was 0.967(3).

The comparison of the correction factors simulated using this new approach with the experimental values determined in this study shows excellent agreement for all magnetic flux densities up to 1.5 T. Integrating the explicit simulation of the collection volume inside the ionization chambers into the MC simulation model significantly improves simulations of the chamber response in magnetic fields. The results presented suggest that intra-type variations for

may be neglectable for ionization chambers of the PTW 30013 type.
Can an injection model replenish filaments in a weak magnetic environment?
Authors: Zou Peng , Jiang Chao-Wei , Wei Feng-Si , Cao Wen-Da
Published: June 2019

We observed an Hα surge that occurred in NOAA Active Region 12401 on 2015 August 17, and we discuss its trigger mechanism, and kinematic and thermal properties. It is suggested that this surge was caused by a chromospheric reconnection which ejected cool and dense material with transverse velocity of about 21–28 km s−1 and initial Doppler velocity of 12 km s−1. This surge is similar to the injection of newly formed filament materials from their footpoints, except that the surge here occurred in a relatively weak magnetic environment of ∼100 G. Thus, we discuss the possibility of filament material replenishment via the erupting mass in such a weak magnetic field, which is often associated with quiescent filaments. It is found that the local plasma can be heated up to about 1.3 times the original temperature, which results in an acceleration of about –0.017 km s−2. It can lift the dense material up to 10 Mm and higher with an inclination angle smaller than 50°, namely the typical height of active region filaments, but it can hardly inject the material up to those filaments higher than 25 Mm, like some quiescent filaments. Thus, we think that the injection model does not work well in describing the formation of quiescent filaments.
Polymer-encapsulated molecular doped epigraphene for quantum resistance metrology
Authors: He Hans , Lara-Avila Samuel , Kim Kyung Ho , Fletcher Nick , Rozhko Sergiy , Bergsten Tobias , Eklund Gunnar , Cedergren Karin , Yakimova Rositsa , Park Yung Woo , Tzalenchuk Alexander , Kubatkin Sergey
Published: June 2019

One of the aspirations of quantum metrology is to deliver primary standards directly to end-users thereby significantly shortening the traceability chains and enabling more accurate products. Epitaxial graphene grown on silicon carbide (epigraphene) is known to be a viable candidate for a primary realisation of a quantum Hall resistance standard, surpassing conventional semiconductor two-dimensional electron gases, such as those based on GaAs, in terms of performance at higher temperatures and lower magnetic fields. The bottleneck in the realisation of a turn-key quantum resistance standard requiring minimum user intervention has so far been the need to fine-tune the carrier density in this material to fit the constraints imposed by a simple cryo-magnetic system. Previously demonstrated methods, such as via photo-chemistry or corona discharge, require application prior to every cool-down as well as specialist knowledge and equipment. To this end we perform metrological evaluation of epigraphene with carrier density tuned by a recently reported permanent molecular doping technique. Measurements at two National Metrology Institutes confirm accurate resistance quantisation below 5 nΩ Ω−1. Furthermore, samples show no significant drift in carrier concentration and performance on multiple thermal cycles over three years. This development paves the way for dissemination of primary resistance standards based on epigraphene.
Rotation in galaxy clusters from MUSIC simulations with the kinetic Sunyaev–Zel’dovich effect
Authors: Baldi A S , De Petris M , Sembolini F , Yepes G , Cui W , Lamagna L
Published: June 2019

The Sunyaev-Zel’dovich effect in galaxy clusters is a unique probe for studying astrophysics and cosmology. We propose in this work its application for the detection of possible coherent rotational motions in the hot intra-cluster medium. We select a sample of massive, relaxed and rotating galaxy clusters from Marenostrum-mUltidark SImulations of galaxy Clusters (MUSIC), and we produce mock maps of the temperature distortion produced by the kinetic Sunyaev–Zel’dovich effect by exploring six different lines of sight, in the best observational condition. These maps are compared with the expected signal computed from a suitable theoretical model in two cases: (i) focusing only on the contribution from the rotation, and (ii) accounting also for the cluster bulk motion. We find that the parameters of the model assumed for the radial profile of the rotational velocity, averaged over the considered lines of sight, are in agreement within two standard deviations at most with independent estimates from the simulation data, without being significantly affected by the presence of the cluster bulk term. The amplitude of the rotational signal is, on average, of the order of 23 per cent of the total signal accounting also for the cluster bulk motion, and its values are consistent with the literature. The projected bulk velocity of the cluster is also recovered at the different lines of sight, with values in agreement with the simulation data.