bluuebunny/crossref_metadata_2025 huggingface dataset:
Character of the Englacial and Subglacial Drainage System in the Upper Part of the Ablation Area of Storglaciären, Sweden
Authors: Hooke Roger Leb. , Miller Sarah B. , Kohler Jack
Published: September 2017

On 4 July 1986, dye was injected at a point slightly above the equilibrium line on Storglaciären, a small valley glacier in northern Sweden. Just below the equilibrium line, the glacier bed is over-deepened. The dye re-appeared in a stream at the glacier terminus over the next 35 d. This stream normally carries relatively little sediment, in constrast to the situation in another nearby stream that also emerges from the glacier. This suggests that the dye traveled in englacial rather than subglacial conduits. Tracer tests utilizing salt in bore holes in the overdeepening support this interpretation, as the bore holes were draining well above the bed. The dye appeared during three distinct events, suggesting that it became divided into at least three separate parcels shortly after injection. This probably occurred in the crevassed area in the vicinity of the injection point.

The englacial location of the drainage may be explained by the fact that, in order to remain at the pressure melting-point, water in subglacial conduits coming out of the overdeepening may have had to warm up faster than would be possible by viscous heating alone. Such conduits would thus tend to freeze closed.
Acoustic Emission Methods Applied to Avalanche-Formation Studies
Authors: Yepifanov V. P. , Kuz'menko V. P.
Published: September 2017

The relationship between the intensity of snow acoustic emission impulses and snow-cover stability is revealed by measuring the physical and mechanical properties of the snow cover in the starting zones of avalanches. This relationship is fundamental to the remote identification of an avalanche-hazard period.

In order to estimate the mechanical properties of a snow layer, a method of applying a rigid penetrometer equipped with a piezo-electric accelerometer is used. The viscosity coefficients of snow under destruction and the specific energy of destruction are determined. The overall effect of different elements of destruction is assessed using both structural investigations and acoustic methods (acoustic emissions).
Internal Geometry and Evolution of Moulins, Storglaciären, Sweden
Authors: Holmlund Per
Published: September 2017

The initial conditions needed for formation of moulins are crevasses and a supply of melt water. Water pouring into a crevasse may fill it until it overflows at the lowest point, which is normally near the margin. However, as the crevasse deepens, it intersects englacial channels through which the water can drain. These channels may be finger-tip tributaries in a dendritic system such as that described by Shreve (1972) and observed by Raymond and Harrison (1975). When the crevasse closes, heat in the melt water keeps the connection open and a moulin is formed. The englacial channel enlarges rapidly by melting, utilizing mechanical energy released by the descending water.

Descents into moulins, and mapping of structures exposed at the surface after many years of melting, demonstrate that the drainage channels leading down from the bottoms of the moulins have inclinations of 0–45° from the vertical. These channels trend in the direction of the original crevasse but appear to be deeper than the expected depth of the crevasse. They have not, even at depths of 50–60 m, become normal to the equipotential planes described by Shreve.
Microcomputer-Based Image-Processing System
Authors: Perovich Donald K. , Hirai Akira
Published: September 2017

Inexpensive add-on boards are currently available that enable personal computers to be used as digital image-processing systems. The capabilities of one such system are illustrated by two specific cases examining the surface characterization of a sea-ice cover and the statistical description of sea-ice structure. The unit discussed digitizes video input into a 512 × 512 array of pixels, assigning each a gray shade from 0 to 255. A key feature of the system is that the primitive commands of the board can be accessed through higher-level programming languages. This allows users to customize easily the system for their own needs.
The Mechanics of Glacier Flow
Authors: Nye J. F.
Published: September 2017

The flow of valley glaciers is examined in the light of recent laboratory experiments on the behaviour of ice under load. Simple expressions are given for the velocity distributions in some cases of laminar flow, and the modification of a pure laminar flow theory necessary to explain the formation of transverse crevasses and thrust planes is considered. The paper ends with some remarks about the formation of crevasse patterns on the surfaces of glaciers. The statical equilibrium of a circular ice cap is discussed in an appendix.
Observations on the Quasi-Viscous Behaviour of Ice in a Tunnel in the Z’mutt Glacier
Authors: Haefeli R.
Published: September 2017

It is suggested that both discontinuous shearing and continuous flow (creep) may coexist in one and the same glacier, provided the stress is high enough for the shear resistance to be reached. Experiments made in a tunnel in the Z’Mutt Glacier suggest that all the motion here observed was continuous, and also show that the viscosity is influenced by the stress conditions. A series of tests made by forcing a ball into the ice also enabled estimates of the viscosity and melting pressure to be made and emphasized the importance of melting in glacier flow.
Experiments on the Deformation of Ice
Authors: Glen J. W.
Published: September 2017

This paper describes compression tests at −1.5° C. on blocks of ice containing many small crystals in random orientation. Results show that ice does not possess a constant coefficient of viscosity, but obeys a more complicated relation between compressive stress u and strain rate . For the stress range 1.5–10 Kg. cm−2 this relation is approximately of the form , where n is a constant equal to about 4. A method of preparing small cylindrical single crystals of ice of a desired orientation is also described.
The Internal Structure of a Cirque Glacier: Report on Studies of the Englacial Movements and Temperatures
Authors: McCall J. G.
Published: September 2017

This report is of a preliminary nature; detailed analyses are being carried on at the present time. The tunnel project on a small cirque glacier in the Jotunheim area of Norway, made possible observations of englacial movements in August and December of 1951 which are correlated with surface movements. Emphasis was placed on detailed three-dimensional studies. A marked divergence of flow lines was noted in both the vertical and horizontal planes. Bands previously thought to be thrust planes were found to be of sedimentary origin and not to be discrete planes of shear. Rates of contractions of tunnel sections up to a depth of 50 m. were observed and the englacial temperature distributions were taken in both zones of ablation and accumulation.
Carbon Dioxide Physiological Training at NASA
Authors: Law Jennifer , Young Millennia , Alexander David , Mason Sara S. , Wear Mary L. , Méndez Claudia M. , Stanley David , Ryder Valerie Meyers , Van Baalen Mary
Published: September 2017

INTRODUCTION: Astronauts undergo CO2 exposure training to recognize their symptoms that can arise acutely both on the ground and in spaceflight. This article describes acute CO2 exposure training at NASA and examines the symptoms reported by astronauts during
training.METHODS: In a controlled training environment, astronauts are exposed to up to 8% CO2 (60 mmHg) by a rebreathing apparatus. Symptoms are reported using a standard form.RESULTS: Symptom documentation forms between April 1994 and February 2012 were obtained
for 130 astronauts. The number of symptoms reported per session out of the possible 24 was related to age and sex, with those older slightly more likely to report symptoms. Women reported more symptoms on average than men (men: 3.7, women: 4.7). Respiratory symptoms (90%), flushing sensation/sweating
(56%), and dizziness/feeling faint/lightheadedness (43%) were the top symptoms. Only headache reached statistical significance in differences between men (13%) and women (37%) after adjustment for multiple testing. Among those with multiple training sessions, respiratory symptoms were the
most consistently reported.DISCUSSION: CO2 exposure training is an important tool to educate astronauts about their potential acute CO2 symptoms. Wide interindividual and temporal variations were observed in symptoms reported during astronaut CO2
exposure training. Headache could not be relied on as a marker of acute exposure during testing since fewer than half the subjects reported it. Our results support periodic refresher training since symptoms may change over time. Further study is needed to determine the optimal interval of
training to maximize symptom recognition and inform operational decisions.Law J, Young M, Alexander D, Mason SS, Wear ML, Méndez CM, Stanley D, Meyers Ryder V, Van Baalen M. Carbon dioxide physiological training at NASA. Aerosp Med Hum Perform. 2017; 88(10):897–902.
Idiopathic Syringomyelia in a Military Helicopter Pilot
Authors: Schiemer Anthony
Published: September 2017

BACKGROUND: A syrinx is a fluid-filled cavity within the spinal cord. They can lead to a variety of symptoms, including limb weakness and back pain. Incidental finding of syringomyelia provides a challenge for clinicians due to the wide variety of possible symptoms. In military
aviation, neurological findings in pilots can result in extensive investigation that can lead to potentially invasive management. Conversely, the potential for chronic progression of a spinal syrinx and subsequent neurological deterioration makes early identification critical. Ultimately,
the discovery of a lesion may have implications for flying status and operational capability.CASE REPORT: A 25-yr-old man working as a navy Seahawk helicopter pilot presented with episodes of right arm paraesthesia and pain between the scapulae. On at least one occasion, these symptoms
woke him at night. Upon magnetic resonance imaging, dilatation of the central canal in a syrinx-like pattern in the lower cervical region was noted. Neurology review suggested the finding was persistent and unlikely to be responsible for his symptoms. No surgical input was recommended. His
symptoms were attributed to mild cervical spondylosis, which resolved with ongoing physiotherapy, and he was returned to flying status.DISCUSSION: This case highlights several issues involved with the incidental finding of a syringomyelia. Surgical intervention has been known to
worsen symptoms. Conversely, studies have identified minimal radiological progression in cases of idiopathic syringomyelia, with fewer individuals displaying neurological deterioration. For aircrew, potentially unnecessary neurosurgical intervention poses risks to a flying career and overall
operational capability.Schiemer A. Idiopathic syringomyelia in a military helicopter pilot. Aerosp Med Hum Perform. 2017; 88(10):962–965.
Analysis of Radar and ADS-B Influences on Aircraft Detect and Avoid (DAA) Systems
Authors: Semke William , Allen Nicholas , Tabassum Asma , McCrink Matthew , Moallemi Mohammad , Snyder Kyle , Arnold Evan , Stott Dawson , Wing Michael
Published: September 2017

Detect and Avoid (DAA) systems are complex communication and locational technologies comprising multiple independent components. DAA technologies support communications between ground-based and space-based operations with aircraft. Both manned and unmanned aircraft systems (UAS) rely on DAA communication and location technologies for safe flight operations. We examined the occurrence and duration of communication losses between radar and automatic dependent surveillance–broadcast (ADS-B) systems with aircraft operating in proximate airspace using data collected during actual flight operations. Our objectives were to identify the number and duration of communication losses for both radar and ADS-B systems that occurred within a discrete time period. We also investigated whether other unique communication behavior and anomalies were occurring, such as reported elevation deviations. We found that loss of communication with both radar and ADS-B systems does occur, with variation in the length of communication losses. We also discovered that other unexpected behaviors were occurring with communications. Although our data were gathered from manned aircraft, there are also implications for UAS that are operating within active airspaces. We are unaware of any previously published work on occurrence and duration of communication losses between radar and ADS-B systems.
Antimony Oxide-Doped 0.99Pb(Zr0.53Ti0.47)O3–0.01Bi(Y1−xSbx)O3 Piezoelectric Ceramics for Energy-Harvesting Applications
Authors: Mahmud Iqbal , Yoon Man-Soon , Ur Soon-Chul
Published: September 2017

The effects of doping antimony oxides (Sb2O3/Sb2O5) on the ferroelectric/piezoelectric and energy-harvesting properties of 0.99Pb(Zr0.53Ti0.47)O3–0.01BiYO3 (PZT–BY) have been studied. The feasibility of doping Sb2O3 and Sb2O5 into the PZT–BY ceramics has also been compared by considering factors such as sintering condition, grain size, density, and electrical properties etc. This work discusses a detailed experimental observation using Sb2O3, because Sb2O5 is relatively expensive and does not follow the stoichiometric reaction mechanism when doped in PZT–BY. The Sb2O3-doped specimens were well sintered by oxygen-rich sintering and reached a maximum density of 99.1% of the theoretical value. X-ray diffraction (XRD) analysis showed a complete solid solution for all the specimens. Scanning electron microscope (SEM) observation revealed that the addition of Sb2O3 inhibits grain growth, and exhibits a denser and finer microstructure. The 0.1 moles of Sb2O3-doped ceramic shows a sharp decrease in the dielectric constant (ε33T = 690), while the piezoelectric charge constant (d33) and electromechanical coupling factor (kp) maintained high values of 350 pC/N and 66.0% respectively. The relatively higher value of d33 and lower ε33T of the 0.99Pb(Zr0.53Ti0.47)O3–0.01Bi(Y0.9Sb0.1)O3 ceramic resulted in an optimum value of piezoelectric voltage constant (g33 = 57.4 × 10−3 Vm/N) and a high figure of merit (d33 × g33 = 20075 × 10−15 m2/N). These values are high compared to recently reported works. Therefore, Sb2O3-doped PZT–BY ceramic could be a promising candidate material for the future study of power-harvesting devices.
Fe-Substitution for Ni in Misch Metal-Based Superlattice Hydrogen Absorbing Alloys—Part 2. Ni/MH Battery Performance and Failure Mechanisms
Authors: Meng Tiejun , Young Kwo-Hsiung , Nei Jean , Koch John , Yasuoka Shigekazu
Published: September 2017

The electrochemical performance and failure mechanisms of Ni/MH batteries made with a series of the Fe-substituted A2B7 superlattice alloys as the negative electrodes were investigated. The incorporation of Fe does not lead to improved cell capacity or cycle life at either room or low temperature, although Fe promotes the formation of a favorable Ce2Ni7 phase. Fe-substitution was found to inhibit leaching of Al from the metal hydride negative electrode and promote leaching of Co, which could potentially extend the cycle life of the positive electrode. The failure mechanisms of the cycled cells with the Fe-substituted superlattice hydrogen absorbing alloys were analyzed by scanning electron microscopy, energy dispersive spectroscopy and inductively coupled plasma analysis. The failure of cells with Fe-free and low Fe-content alloys is mainly attributed to the pulverization of the metal hydride alloy. Meanwhile, severe oxidation/corrosion of the negative electrode is observed for cells with high Fe-content alloys, resulting in increased internal cell resistance, formation of micro-shortages in the separator and eventual cell failure.
Integrin Activation Contributes to Lower Cisplatin Sensitivity in MV3 Melanoma Cells by Inducing the Wnt Signalling Pathway
Authors: Piva Maria , Jakubzig Bastian , Bendas Gerd
Published: September 2017

Background: integrins have been associated with the development of chemotherapy resistant tumour cells, mostly those of hematopoietic origin, by mediating the binding to the extracellular matrix. The relevance for solid tumour cells and the underlying mechanisms remain elusive. Methods: using MTT assays, we detected the loss in cisplatin sensitivity of human MV3 melanoma cells upon integrin activation. Underlying cellular pathways were evaluated by flow cytometry. A crosstalk between integrin activation and the canonical wnt signalling pathway was tested by measuring β-catenin activity. Results: MV3 cells display a higher resistance against cisplatin cytotoxicity when cellular integrins were activated by manganese or collagen. Proteome profiler array showed a deregulation of the integrin expression pattern by cisplatin. Integrin activation by manganese induces the phosphorylation of PI3K/AKT. The inhibition of PI3K using BEZ235 strongly increases cell sensitivity to cisplatin, blocking manganese and collagen effects. PI3K/AKT activates wnt signalling by blocking Gsk3-β, which was confirmed by β-catenin up-regulation and nuclear localization. Integrins did not affect E-cadherin expression levels, thus endothelial to mesenchymal transition (EMT) can be excluded. Conclusion: This is the first report on an integrin/wnt signalling activation axis addressing the consequences for chemotherapy sensitiveness of melanoma cells, which thus offers novel therapeutic targets for approaches to interfere with chemoresistance.
The Preparation of a Highly Efficient Ag3PO4/Ag/Bi2O2CO3 Photo-Catalyst and the Study of Its Photo-Catalytic Organic Synthesis Reaction Driven by Visible Light
Authors: Guo Zhi , Xin Hui , Ma Jingjing , Bai Meifen , Wang Yan , Li Jingyi
Published: September 2017

Ag3PO4/Ag/Bi2O2CO3 composites were prepared by a hydrothermal and precipitation method. The morphology, structure, and valence state of the photo-catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) specific surface areas, and UV-vis diffuse reflectance spectra (UV-vis DRS). They were applied as heterogeneous catalysts in the synthesis of esters from aldehydes (or alcohols) and alcohols and the synthesis of imines from alcohols and amines under visible light irradiation. The photo-catalytic activities of the esterification reactions of aldehydes and alcohols were heavily dependent on the loading of Ag3PO4/Ag/Bi2O2CO3 as well as the intensity and wavelength of the visible light. Furthermore, their conversion under visible light irradiation was superior to that in the dark. Herein a reaction mechanism from aldehydes and alcohols to esters was proposed, and the Ag3PO4/Ag/Bi2O2CO3 catalysts could be used six times without a significant decrease in activity. Using these catalysts under visible light could motivate future studies to develop efficient recyclable photo-catalysts and facilitate many synthetic organic reactions.
Surface Oxidation of Supported Ni Particles and Its Impact on the Catalytic Performance during Dynamically Operated Methanation of CO2
Authors: Mutz Benjamin , Gänzler Andreas , Nachtegaal Maarten , Müller Oliver , Frahm Ronald , Kleist Wolfgang , Grunwaldt Jan-Dierk
Published: September 2017

The methanation of CO2 within the power-to-gas concept was investigated under fluctuating reaction conditions to gather detailed insight into the structural dynamics of the catalyst. A 10 wt % Ni/Al2O3 catalyst with uniform 3.7 nm metal particles and a dispersion of 21% suitable to investigate structural changes also in a surface-sensitive way was prepared and characterized in detail. Operando quick-scanning X-ray absorption spectroscopy (XAS/QEXAFS) studies were performed to analyze the influence of 30 s and 300 s H2 interruptions during the methanation of CO2 in the presence of O2 impurities (technical CO2). These conditions represent the fluctuating supply of H2 from renewable energies for the decentralized methanation. Short-term H2 interruptions led to oxidation of the most reactive low-coordinated metallic Ni sites, which could not be re-reduced fully during the subsequent methanation cycle and accordingly caused deactivation. Detailed evaluation of the extended X-ray absorption fine structure (EXAFS) spectra showed surface oxidation/reduction processes, whereas the core of the Ni particles remained reduced. The 300-s H2 interruptions resulted in bulk oxidation already after the first cycle and a more pronounced deactivation. These results clearly show the importance and opportunities of investigating the structural dynamics of catalysts to identify their mechanism, especially in power-to-chemicals processes using renewable H2.
Germination Phenological Response Identifies Flora Risk to Climate Change
Authors: Chhetri Sarala , Rawal Deepa
Published: September 2017

Climate change is prevalent across the world and can have large influence on plant regeneration, recruitment, survival and diversity. Regeneration and recruitment are the key phases in the plant life cycle and these two aspects are related to survival, adaptation and distribution of species. This study thus aims to explore the effect of projected climate change on germination and establishment response of some timber tree species from the tropical/subtropical broad leaf forests of Nepal. Germination experiments were carried out under three different temperature regimes (20, 25 and 30 °C) and germination parameters identified from the experimental component were calibrated in the mechanistic model Tree and Climate Assessment—Germination and Establishment Module (TACA-GEM) that helped in identifying species vulnerability to climate change. The model outcome under varied climatic conditions helped in determining the species risk to projected climatic conditions. The model demonstrates that the studied species were able to increase germination under the projected climate change however, establishment consistently failed for most of the species across the hot tropical sites. This finding indicates that spatial vulnerability may limit recruitment in the future. The species-specific responses suggest that, in general, all three species (Alnus nepalensis, Adina cordifolia, and Bombax ceiba) exhibited enhanced germination and establishment in moderately warm and colder sites, indicating that these species may more likely shift their range towards the north in future. Thus, the general species response exhibited in this study may aid in regional climate change adaptation planning in the sector of forest conservation and management.
Decreasing Past and Mid-Century Rainfall Indices over the Ouémé River Basin, Benin (West Africa)
Authors: N’Tcha M’Po Yèkambèssoun , Lawin Emmanuel , Yao Benjamin , Oyerinde Ganiyu , Attogouinon André , Afouda Abel
Published: September 2017

This study analyzed the trends of extreme daily rainfall indices over the Ouémé basin using the observed data from 1950 to 2014 and the projected rainfall of regional climate model REMO (REgional MOdel) for the period 2015–2050. For future trends analysis, two Intergovernmental Panel on Climate Change (IPCC) new scenarios are considered, namely RCP4.5 and RCP8.5. The indices considered are number of heavy rainfall days, number of very heavy rainfall days, consecutive dry days, consecutive wet days, daily maximum rainfall, five-day maximum rainfall, annual wet-day total rainfall, simple daily intensity index, very wet days, and extremely wet days. These indices were calculated at annual and seasonal scales. The Mann-Kendall non-parametric test and the parametric linear regression approach were used for trends detection. As result, significant declining in the number of heavy and very heavy rainfall days, heavy and extremely heavy rainfall, consecutive wet days and annual wet-day rainfall total were detected in most stations for the historical period as well as the future period following the scenario RCP8.5. Furthermore, few stations presented significant trends for the scenario RCP4.5 and the high proportion of stations with the inconsistence trends invites the planners to get ready for an uncertain future climate following this scenario.
Traction Inverter Open Switch Fault Diagnosis Based on Choi–Williams Distribution Spectral Kurtosis and Wavelet-Packet Energy Shannon Entropy
Authors: Lin Shuangshuang , Liu Zhigang , Hu Keting
Published: September 2017

In this paper, a new approach for fault detection and location of open switch faults in the closed-loop inverter fed vector controlled drives of Electric Multiple Units is proposed. Spectral kurtosis (SK) based on Choi–Williams distribution (CWD) as a statistical tool can effectively indicate the presence of transients and locations in the frequency domain. Wavelet-packet energy Shannon entropy (WPESE) is appropriate for the transient changes detection of complex non-linear and non-stationary signals. Based on the analyses of currents in normal and fault conditions, SK based on CWD and WPESE are combined with the DC component method. SK based on CWD and WPESE are used for the fault detection, and the DC component method is used for the fault localization. This approach can diagnose the specific locations of faulty Insulated Gate Bipolar Transistors (IGBTs) with high accuracy, and it requires no additional devices. Experiments on the RT-LAB platform are carried out and the experimental results verify the feasibility and effectiveness of the diagnosis method.
Autoregressive Lag—Order Selection Using Conditional Saddlepoint Approximations
Authors: Butler Ronald , Paolella Marc
Published: September 2017

A new method for determining the lag order of the autoregressive polynomial in regression models with autocorrelated normal disturbances is proposed. It is based on a sequential testing procedure using conditional saddlepoint approximations and permits the desire for parsimony to be explicitly incorporated, unlike penalty-based model selection methods. Extensive simulation results indicate that the new method is usually competitive with, and often better than, common model selection methods.
State-Of-The-Art in Microgrid-Integrated Distributed Energy Storage Sizing
Authors: Alsaidan Ibrahim , Alanazi Abdulaziz , Gao Wenzhong , Wu Hongyu , Khodaei Amin
Published: September 2017

Distributed energy storage (DES) plays an important role in microgrid operation and control, as it can potentially improve local reliability and resilience, reduce operation cost, and mitigate challenges caused by high penetration renewable generation. However, to ensure an acceptable economic and technical performance, DES must be optimally sized and placed. This paper reviews the existing DES sizing methods for microgrid applications and presents a generic sizing method that enables microgrid planners to efficiently determine the optimal DES size, technology, and location. The proposed method takes into consideration the impact of DES operation on its lifetime to enhance the obtained results accuracy and practicality. The presented model can be used for both grid-tied (considering both grid-connected and islanded modes) and isolated microgrids.
Electric Arc Furnace Modeling with Artificial Neural Networks and Arc Length with Variable Voltage Gradient
Authors: Garcia-Segura Raul , Vázquez Castillo Javier , Martell-Chavez Fernando , Longoria-Gandara Omar , Ortegón Aguilar Jaime
Published: September 2017

Electric arc furnaces (EAFs) contribute to almost one third of the global steel production. Arc furnaces use a large amount of electrical energy to process scrap or reduced iron and are relevant to study because small improvements in their efficiency account for significant energy savings. Optimal controllers need to be designed and proposed to enhance both process performance and energy consumption. Due to the random and chaotic nature of the electric arcs, neural networks and other soft computing techniques have been used for modeling EAFs. This study proposes a methodology for modeling EAFs that considers the time varying arc length as a relevant input parameter to the arc furnace model. Based on actual voltages and current measurements taken from an arc furnace, it was possible to estimate an arc length suitable for modeling the arc furnace using neural networks. The obtained results show that the model reproduces not only the stable arc conditions but also the unstable arc conditions, which are difficult to identify in a real heat process. The presented model can be applied for the development and testing of control systems to improve furnace energy efficiency and productivity.
A High-Efficient Low-Cost Converter for Capacitive Wireless Power Transfer Systems
Authors: Lee Il-Oun , Kim Joongheon , Lee Woojoo
Published: September 2017

Growth of the Internet of Things (IoT) spurs need for new ways of delivering power. Wireless power transfer (WPT) has come into the spotlight from both academia and industry as a promising way to power the IoT devices. As one of the well-known WPT techniques, the capacitive power transfer (CPT) has the merit of low electromagnetic radiation and amenability of combined power and data transfer over a capacitive interface. However, applying the CPT to the IoT devices is still challenging in reality. One of the major issues is due to the small capacitance of the capacitive interface, which results in low efficiency of the power transfer. To tackle this problem, we present a new step-up single-switch quasi-resonant (SSQR) converter for the CPT system. To enhance the CPT efficiency, the proposed converter is designed to operate at low frequency and drive small current into the capacitive interfaces. In addition, by eliminating resistor-capacitor-diode (RCD) snubber in the converter, we reduce the implementation cost of the CPT system. Based on intensive experimental work with a CPT system prototype that supports maximum 50 W (100 V/0.5 A) power transfer, we demonstrate the functional correctness of the converter that achieves up to 93% efficiency.
Tuning the Size of Thermoresponsive Poly(N-Isopropyl Acrylamide) Grafted Silica Microgels
Authors: Nun Nils , Hinrichs Stephan , Schroer Martin A. , Sheyfer Dina , Grübel Gerhard , Fischer Birgit
Published: September 2017

Core-shell microgels were synthesized via a free radical emulsion polymerization of thermoresponsive poly-(N-isopropyl acrylamide), pNipam, on the surface of silica nanoparticles. Pure pNipam microgels have a lower critical solution temperature (LCST) of about 32 °C. The LCST varies slightly with the crosslinker density used to stabilize the gel network. Including a silica core enhances the mechanical robustness. Here we show that by varying the concentration gradient of the crosslinker, the thermoresponsive behaviour of the core-shell microgels can be tuned. Three different temperature scenarios have been detected. First, the usual behaviour with a decrease in microgel size with increasing temperature exhibiting an LCST; second, an increase in microgel size with increasing temperature that resembles an upper critical solution temperature (UCST), and; third, a decrease with a subsequent increase of size reminiscent of the presence of both an LCST, and a UCST. However, since the chemical structure has not been changed, the LCST should only change slightly. Therefore we demonstrate how to tune the particle size independently of the LCST.
Taking into Account the Role of the Weathering Profile in Determining Hydrodynamic Properties of Hard Rock Aquifers
Authors: Koïta Mahamadou , Yonli Hamma , Soro Donissongou , Dara Amagana , Vouillamoz Jean-Michel
Published: September 2017

The present study aims at understanding the role of the structure and the geometry of the weathering profile on the hydrodynamic behavior of hard rock aquifers. We first described 2D geophysical cross sections of weathering profiles realized and validated on an experimental site. Next, we implemented five long-term pumping tests in wells drilled at various locations of these cross sections. Finally, we chose the appropriate analytical solutions to determine the hydrodynamic parameters in consistence with the structure and the geometry of the weathering profile. Results reveal that land covers, weathering type and thickness, presence of no flow boundaries, etc. are all factors that explain the flow regime, which appears therefore much less unpredictable. In other words, the 2D geophysical data are enough to locate the best permeable areas, or the areas where the structure of the aquifer without impervious boundaries and with leakage favor a good long-term behavior of the well. The values of aquifer’s transmissivity vary between 5.10−3 and 4.10−5 m2/s. The storage varies between 0.06 and 7.10−7. The variability of these parameters from site to site reflects the high heterogeneity of hard rock aquifers.
Poverty Dynamics and Academic Trajectories of Children of Immigrants
Authors: Zhang Liwei , Han Wen-Jui
Published: September 2017

Using Early Childhood Longitudinal Study, Kindergarten Class of 1998–1999 (ECLS-K), we investigated the relationship between poverty and academic trajectories for children in immigrant families in the United States. We used family socioeconomic status (SES) which considers parental education, parental occupation, and family income to define poverty in correspondence with the U.S. federal poverty threshold. Three dimensions of poverty were examined including depth (i.e., not-poor, near-poor, poor or extreme poor), stability (i.e., continuously or intermittently), and duration (i.e., for how many times in poverty). Our results indicated that living in poverty, particularly when it was extreme, volatile, and for long spell could compromise children’s reading and math achievements during the first nine schooling years. Children of immigrants were doing as well as, if not better than, children of native-borns in certain areas (i.e., math) or in facing of certain pattern of poverty (i.e., long-spell). However, deep poverty and volatile changes in family SES could compromise academic achievements for children of immigrants throughout their first nine years of schooling, a period holds important key to their future success. Implications to practice and policy as well as future directions were discussed.
China’s Air Quality and Respiratory Disease Mortality Based on the Spatial Panel Model
Authors: Cao Qilong , Liang Ying , Niu Xueting
Published: September 2017

Background: Air pollution has become an important factor restricting China’s economic development and has subsequently brought a series of social problems, including the impact of air pollution on the health of residents, which is a topical issue in China. Methods: Taking into account this spatial imbalance, the paper is based on the spatial panel data model PM2.5. Respiratory disease mortality in 31 Chinese provinces from 2004 to 2008 is taken as the main variable to study the spatial effect and impact of air quality and respiratory disease mortality on a large scale. Results: It was found that there is a spatial correlation between the mortality of respiratory diseases in Chinese provinces. The spatial correlation can be explained by the spatial effect of PM2.5 pollutions in the control of other variables. Conclusions: Compared with the traditional non-spatial model, the spatial model is better for describing the spatial relationship between variables, ensuring the conclusions are scientific and can measure the spatial effect between variables.
The Beneficial Effects of Allicin in Chronic Kidney Disease Are Comparable to Losartan
Authors: García Trejo Ehécatl , Arellano Buendía Abraham , Sánchez Reyes Omegar , García Arroyo Fernando , Arguello García Raúl , Loredo Mendoza María , Tapia Edilia , Sánchez Lozada Laura , Osorio Alonso Horacio
Published: September 2017

Recent studies suggest that allicin may play a role in chronic kidney disease (CKD), reducing hypertension and oxidative stress and improving renal dysfunction. In the present study, CKD was induced by 5/6 nephrectomy and the animals were divided into four treatment groups as follows: control (C), CKD, CKD+allicin (40 mg/kg pathway oral) (CKDA), and CKD+Losartan (20 mg/kg) (CKDL). After CKD induction, the rats developed hypertension from week 3 to the end of the study. This was associated with increased creatinine and blood urea nitrogen (BUN) levels in serum, increased albuminuria, increased urinary excretion of N-acetyl-β-d-glucosaminidase (NAG), increased nephrin expression, and incrased histological alterations in the cortex. The levels of angiotensin receptors and endothelial nitric oxide synthase (eNOS) were decreased in the renal cortex from the CKD group. Otherwise, lipid and protein oxidation were higher in the CKD group than in the control group. A disturbance was observed in the expression levels of the nuclear factor erythroid 2-related factor 2/Kelch ECH associating protein 1 system (Nrf2/keap1) and the antioxidant enzymes catalase, superoxide dismutase, and heme oxygenase-1. Allicin or losartan treatments relieved renal dysfunction, hypertension, and oxidative stress. In addition, both treatments showed the same efficacy on the expression of angiotensin receptors, the nephrin, Nrf2/keap1 pathway, and eNOS. Further in silico analyses suggest that allicin and losartan could have a common mechanism involving interaction with AT1 receptors. Allicin showed antihypertensive, antioxidant, and nephroprotective effects. The beneficial effects showed by allicin are similar, or even better, than those of losartan. In fact, the effect of allicin on blood pressure and renal function is comparable to reductions seen with losartan, a prescription drug commonly used as a first-line therapy.
Genetic and Hormonal Regulation of Chlorophyll Degradation during Maturation of Seeds with Green Embryos
Authors: Smolikova Galina , Dolgikh Elena , Vikhnina Maria , Frolov Andrej , Medvedev Sergei
Published: September 2017

The embryos of some angiosperms (usually referred to as chloroembryos) contain chlorophylls during the whole period of embryogenesis. Developing embryos have photochemically active chloroplasts and are able to produce assimilates, further converted in reserve biopolymers, whereas at the late steps of embryogenesis, seeds undergo dehydration, degradation of chlorophylls, transformation of chloroplast in storage plastids, and enter the dormancy period. However, in some seeds, the process of chlorophyll degradation remains incomplete. These residual chlorophylls compromise the quality of seed material in terms of viability, nutritional value, and shelf life, and represent a serious challenge for breeders and farmers. The mechanisms of chlorophyll degradation during seed maturation are still not completely understood, and only during the recent decades the main pathways and corresponding enzymes could be characterized. Among the identified players, the enzymes of pheophorbide a oxygenase pathway and the proteins encoded by STAY GREEN (SGR) genes are the principle ones. On the biochemical level, abscisic acid (ABA) is the main regulator of seed chlorophyll degradation, mediating activity of corresponding catabolic enzymes on the transcriptional level. In general, a deep insight in the mechanisms of chlorophyll degradation is required to develop the approaches for production of chlorophyll-free high quality seeds.
The Semi-Synthetic Peptide Lin-SB056-1 in Combination with EDTA Exerts Strong Antimicrobial and Antibiofilm Activity against Pseudomonas aeruginosa in Conditions Mimicking Cystic Fibrosis Sputum
Authors: Maisetta Giuseppantonio , Grassi Lucia , Esin Semih , Serra Ilaria , Scorciapino Mariano , Rinaldi Andrea , Batoni Giovanna
Published: September 2017

Pseudomonas aeruginosa is a major cause of chronic lung infections in cystic fibrosis (CF) patients. The ability of the bacterium to form biofilms and the presence of a thick and stagnant mucus in the airways of CF patients largely contribute to antibiotic therapy failure and demand for new antimicrobial agents able to act in the CF environment. The present study investigated the anti-P. aeruginosa activity of lin-SB056-1, a recently described semi-synthetic antimicrobial peptide, used alone and in combination with the cation chelator ethylenediaminetetraacetic acid (EDTA). Bactericidal assays were carried out in standard culture conditions and in an artificial sputum medium (ASM) closely resembling the CF environment. Peptide’s structure and interaction with large unilamellar vesicles in media with different ionic strengths were also investigated through infrared spectroscopy. Lin-SB056-1 demonstrated fast and strong bactericidal activity against both mucoid and non-mucoid strains of P. aeruginosa in planktonic form and, in combination with EDTA, caused significant reduction of the biomass of P. aeruginosa mature biofilms. In ASM, the peptide/EDTA combination exerted a strong bactericidal effect and inhibited the formation of biofilm-like structures of P. aeruginosa. Overall, the results obtained highlight the potential of the lin-SB056-1/EDTA combination for the treatment of P. aeruginosa lung infections in CF patients.
Expanding the Applicability of Poly(Ionic Liquids) in Solid Phase Microextraction: Pyrrolidinium Coatings
Authors: Patinha David , Tomé Liliana , Isik Mehmet , Mecerreyes David , Silvestre Armando , Marrucho Isabel
Published: September 2017

Crosslinked pyrrolidinium-based poly(ionic liquids) (Pyrr-PILs) were synthesized through a fast, simple, and solventless photopolymerization scheme, and tested as solid phase microextraction (SPME) sorbents. A series of Pyrr-PILs bearing three different alkyl side chain lengths with two, eight, and fourteen carbons was prepared, characterized, and homogeneously coated on a steel wire by using a very simple procedure. The resulting coatings showed a high thermal stability, with decomposition temperatures above 350 °C, excellent film stability, and lifetime of over 100 injections. The performance of these PIL-based SPME fibers was evaluated using a mixture of eleven organic compounds with different molar volumes and chemical functionalities (alcohols, ketones, and monoterpenes). The Pyrr-PIL fibers were obtained as dense film coatings, with 67 μm thickness, with an overall sorption increase of 90% and 55% as compared to commercial fibers of Polyacrylate (85 μm) (PA85) and Polydimethylsiloxane (7 μm) (PDMS7) coatings, respectively. A urine sample doped with the sample mixture was used to study the matrix effect and establish relative recoveries, which ranged from 60.2% to 104.1%.
Strengthening of Existing Bridge Structures for Shear and Bending with Carbon Textile-Reinforced Mortar
Authors: Herbrand Martin , Adam Viviane , Classen Martin , Kueres Dominik , Hegger Josef
Published: September 2017

Increasing traffic loads and changes in code provisions lead to deficits in shear and flexural capacity of many existing highway bridges. Therefore, a large number of structures are expected to require refurbishment and strengthening in the future. This projection is based on the current condition of many older road bridges. Different strengthening methods for bridges exist to extend their service life, all having specific advantages and disadvantages. By applying a thin layer of carbon textile-reinforced mortar (CTRM) to bridge deck slabs and the webs of pre-stressed concrete bridges, the fatigue and ultimate strength of these members can be increased significantly. The CTRM layer is a combination of a corrosion resistant carbon fiber reinforced polymer (CFRP) fabric and an efficient mortar. In this paper, the strengthening method and the experimental results obtained at RWTH Aachen University are presented.
Physical-Mechanism Exploration of the Low-Cycle Unified Creep-Fatigue Formulation
Authors: Liu Dan , Pons Dirk
Published: September 2017

Background—Creep-fatigue behavior is identified as the incorporated effects of fatigue and creep. One class of constitutive-based models attempts to evaluate creep and fatigue separately, but the interaction of fatigue and creep is neglected. Other models treat the damage as a single component, but the complex numerical structures that result are inconvenient for engineering application. The models derived through a curve-fitting method avoid these problems. However, the method of curving fitting cannot translate the numerical formulation to underlying physical mechanisms. Need—Therefore, there is a need to develop a new creep-fatigue formulation for metal that accommodates all relevant variables and where the relationships between them are consistent with physical mechanisms of fatigue and creep. Method—In the present work, the main dependencies and relationships for the unified creep-fatigue equation were presented through exploring what the literature says about the mechanisms. Outcomes—This shows that temperature, cyclic time and grain size have significant influences on creep-fatigue behavior, and the relationships between them (such as linear relation, logarithmical relation and power-law relation) are consistent with phenomena of diffusion creep and crack growth. Significantly, the numerical form of “1 − x” is presented to show the consumption of creep effect on fatigue capacity, and the introduction of the reference condition gives the threshold of creep effect. Originality—By this means, the unified creep-fatigue equation is linked to physical phenomena, where the influence of different dependencies on creep fatigue was explored and relationships shown in this equation were investigated in a microstructural level. Particularly, a physical explanation of the grain-size exponent via consideration of crack-growth planes was proposed.
Effect of Computational Parameters on Springback Prediction by Numerical Simulation
Authors: Trzepiecinski Tomasz , Lemu Hirpa
Published: September 2017

Elastic recovery of the material, called springback, is one of the problems in sheet metal forming of drawpieces, especially with a complex shape. The springback can be influenced by various technological, geometrical, and material parameters. In this paper the results of experimental testing and numerical study are presented. The experiments are conducted on DC04 steel sheets, commonly used in the automotive industry. The numerical analysis of V-die air bending tests is carried out with the finite element method (FEM)-based ABAQUS/Standard 2016 program. A quadratic Hill anisotropic yield criterion is compared with an isotropic material described by the von Mises yield criterion. The effect of a number of integration points and integration rules on the springback amount and computation time is also considered. Two integration rules available in ABAQUS: the Gauss’ integration rule and Simpson’s integration rule are considered. The effect of sample orientation according to the sheet rolling direction and friction contact behaviour on the prediction of springback is also analysed. It is observed that the width of the sample bend in the V-bending test influences the stress-state in the cross-section of the sample. Different stress-states in the sample bend of the V-shaped die cause that the sheet undergoes springback in different planes. Friction contact phenomena slightly influences the springback behaviour.