bluuebunny/crossref_metadata_2025 huggingface dataset:
Inhibition of Tumor Growth via Systemic siRNA Delivery Using Reducible Bile Acid-Conjugated Polyethylenimine
Authors: Yin Yue , Lee Jung , Kim Nak , Lee Jong , Lim Su , Kim E , Park Ji , Lee Min , Jeong Ji
Published: August 2018

RNA interference (RNAi), mediated by small interfering RNA (siRNA), has been considered as a potential therapeutic agent for cancer owing to its ability to suppress target genes in a sequence-specific manner. In this study, a conjugate of the low molecular weight (MW) polyethylenimine (PEI) (MW 1800) and deoxycholic acid (DA) was further modified with 4-fluorothiophenol (FTP) (TP-DA-PEI) to achieve systemic siRNA delivery. The thiophenol group would be involved with disulfide bonds between the polymer chains and siRNA modified with free thiols (thiol-siRNA) to form and π–π interactions between the pendent aromatic groups and coprostane ring of the bile acid. The TP-DA-PEI conjugates could generate stable nanoparticles with thiol-siRNA. The TP-DA-PEI conjugate not only achieved enhanced intracellular uptake, serum stability, and transfection efficiency, but also showed high accumulation of TP-DA-PEI/thiol-siRNA polyplexes and significant tumor growth inhibition effect in tumor-bearing mice after systemic administration.
On the Very High-Resolution Radar Image Statistics of the Exponentially Correlated Rough Surface: Experimental and Numerical Studies
Authors: Jin Ming , Chen Kun-Shan , Xie Dengfeng
Published: August 2018

The aim of this study is to investigate, by means of experimental measurements and full-wave simulations, the dominant factors for the very high-resolution (VHR) radar image speckles from exponentially correlated rough surfaces. A Ka-band radar system was used to collect the return signal from such a surface sample fabricated by 3D printing and that signal was further processed into images at different resolution scales, where the image samples were obtained by horizontally turning around the surface sample. To cross-validate the results and to further discuss the VHR speckle properties, full wave simulations by full 3D Finite Difference Time Domain (FDTD) method were conducted with 1600 realizations for the speckle analysis. At the considered very high resolution, speckle statistics show divergence from the fully developed Rayleigh distribution. The factors that impact on the high-resolution speckle properties from exponentially correlated rough surface, are analyzed in views of the equivalent number of scatterers theory and scattering scales, respectively. From the data results and extended discussions, it is evident that both of the above factors matter for VHR speckle of backscattering, from the exponentially correlated rough surface as a good representative for the ground surface.
Hand Tracking and Gesture Recognition Using Lensless Smart Sensors
Authors: Abraham Lizy , Urru Andrea , Normani Niccolò , Wilk Mariusz P. , Walsh Michael , O’Flynn Brendan
Published: August 2018

The Lensless Smart Sensor (LSS) developed by Rambus, Inc. is a low-power, low-cost visual sensing technology that captures information-rich optical data in a tiny form factor using a novel approach to optical sensing. The spiral gratings of LSS diffractive grating, coupled with sophisticated computational algorithms, allow point tracking down to millimeter-level accuracy. This work is focused on developing novel algorithms for the detection of multiple points and thereby enabling hand tracking and gesture recognition using the LSS. The algorithms are formulated based on geometrical and mathematical constraints around the placement of infrared light-emitting diodes (LEDs) on the hand. The developed techniques dynamically adapt the recognition and orientation of the hand and associated gestures. A detailed accuracy analysis for both hand tracking and gesture classification as a function of LED positions is conducted to validate the performance of the system. Our results indicate that the technology is a promising approach, as the current state-of-the-art focuses on human motion tracking that requires highly complex and expensive systems. A wearable, low-power, low-cost system could make a significant impact in this field, as it does not require complex hardware or additional sensors on the tracked segments.
Lightweight Visual Odometry for Autonomous Mobile Robots
Authors: Aladem Mohamed , Rawashdeh Samir A.
Published: August 2018

Vision-based motion estimation is an effective means for mobile robot localization and is often used in conjunction with other sensors for navigation and path planning. This paper presents a low-overhead real-time ego-motion estimation (visual odometry) system based on either a stereo or RGB-D sensor. The algorithm’s accuracy outperforms typical frame-to-frame approaches by maintaining a limited local map, while requiring significantly less memory and computational power in contrast to using global maps common in full visual SLAM methods. The algorithm is evaluated on common publicly available datasets that span different use-cases and performance is compared to other comparable open-source systems in terms of accuracy, frame rate and memory requirements. This paper accompanies the release of the source code as a modular software package for the robotics community compatible with the Robot Operating System (ROS).
Localization and Discrimination of the Perturbation Signals in Fiber Distributed Acoustic Sensing Systems Using Spatial Average Kurtosis
Authors: Jiang Fei , Li Honglang , Zhang Zhenhai , Zhang Yixin , Zhang Xuping
Published: August 2018

Location error and false alarm are noticeable problems in fiber distributed acoustic sensing systems based on phase-sensitive optical time-domain reflectometry (Φ-OTDR). A novel method based on signal kurtosis is proposed to locate and discriminate perturbations in Φ-OTDR systems. The spatial kurtosis (SK) along the fiber is firstly obtained by calculating the kurtosis of acoustic signals at each position of the fiber in a short time period. After the moving average on the spatial dimension, the spatial average kurtosis (SAK) is then obtained, whose peak can accurately locate the center of the vibration segment. By comparing the SAK value with a certain threshold, we may to some degree discriminate the instantaneous destructive perturbations from the system noise and certain ambient environmental interferences. The experimental results show that, comparing with the average of the previous localization methods, the SAK method improves the pencil-break and digging locating signal-to-noise ratio (SNR) by 16.6 dB and 17.3 dB, respectively; and decreases the location standard deviation by 7.3 m and 9.1 m, respectively. For the instantaneous destructive perturbation (pencil-break and digging) detection, the false alarm rate can be as low as 1.02%, while the detection probability is maintained as high as 95.57%. In addition, the time consumption of the SAK method is adequate for a real-time Φ-OTDR system.
A Separated Calibration Method for Inertial Measurement Units Mounted on Three-Axis Turntables
Authors: Dong Chun-mei , Ren Shun-qing , Chen Xi-jun , Wang Zhen-huan
Published: August 2018

Inertial Measurement Unit (IMU) calibration accuracy is easily affected by turntable errors, so the primary aim of this study is to reduce the dependence on the turntable’s precision during the calibration process. Firstly, the indicated-output of the IMU considering turntable errors is constructed and with the introduction of turntable errors, the functional relationship between turntable errors and the indicated-output was derived. Then, based on a D-suboptimal design, a calibration method for simultaneously identifying the IMU error model parameters and the turntable errors was proposed. Simulation results showed that some turntable errors could thus be effectively calibrated and automatically compensated. Finally, the theoretical validity was verified through experiments. Compared with the traditional method, the method proposed in this paper can significantly reduce the influence of the turntable errors on the IMU calibration accuracy.
Analysis of Sustainable Materials for Radiative Cooling Potential of Building Surfaces
Authors: Family Roxana , Mengüç M. Pinar
Published: August 2018

The main goal of this paper is to explore the radiative cooling and solar heating potential of several materials for the built environment, based on their spectrally-selective properties. A material for solar heating, should have high spectral emissivity/absorptivity in the solar radiation band (within the wavelength range of 0.2–2 μm), and low emissivity/absorptivity at longer wavelengths. Radiative cooling applications require high spectral emissivity/absorptivity, within the atmospheric window band (8–13 μm), and a low emissivity/absorptivity in other bands. UV-Vis spectrophotometer and FTIR spectroscopy, are used to measure, the spectral absorption/emission spectra of six different types of materials. To evaluate the radiative cooling potential of the samples, the power of cooling is calculated. Heat transfer through most materials is not just a surface phenomenon, but it also needs a volumetric analysis. Therefore, a coupled radiation and conduction heat transfer analysis is used. Results are discussed for the selection of the best materials, for different applications on building surfaces.
Land Use and Land Cover Dynamics and Assessing the Ecosystem Service Values in the Trans-Boundary Gandaki River Basin, Central Himalayas
Authors: Rai Raju , Zhang Yili , Paudel Basanta , Acharya Bipin Kumar , Basnet Laxmi
Published: August 2018

Land use and land cover is a fundamental variable that affects many parts of social and physical environmental aspects. Land use and land cover changes (LUCC) has been known as one of the key drivers of affecting in ecosystem services. The trans-boundary Gandaki River Basin (GRB) is the part of Central Himalayas, a tributary of Ganges mega-river basin plays a crucial role on LUCC and ecosystem services. Due to the large topographic variances, the basin has existed various land cover types including cropland, forest cover, built-up area, river/lake, wetland, snow/glacier, grassland, barren land and bush/shrub. This study used Landsat 5-TM (1990), Landsat 8-OLI (2015) satellite image and existing national land cover database of Nepal of the year 1990 to analyze LUCC and impact on ecosystem service values between 1990 and 2015. Supervised classification with maximum likelihood algorithm was applied to obtain the various land cover types. To estimate the ecosystem services values, this study used coefficients values of ecosystem services delivered by each land cover class. The combined use of GIS and remote sensing analysis has revealed that grassland and snow cover decreased from 10.62% to 7.62% and 9.55% to 7.27%, respectively compared to other land cover types during the 25 years study period. Conversely, cropland, forest and built-up area have increased from 31.78% to 32.67%, 32.47–33.22% and 0.19–0.59%, respectively in the same period. The total ecosystem service values (ESV) was increased from 50.16 × 108 USD y−1 to 51.84 × 108 USD y−1 during the 25 years in the GRB. In terms of ESV of each of land cover types, the ESV of cropland, forest, water bodies, barren land were increased, whereas, the ESV of snow/glacier and grassland were decreased. The total ESV of grassland and snow/glacier cover were decreased from 3.12 × 108 USD y−1 to 1.93 × 108 USD y−1 and 0.26 × 108 USD y−1 to 0.19 × 108 USD y−1, respectively between 1990 and 2015. The findings of the study could be a scientific reference for the watershed management and policy formulation to the trans-boundary watershed.
Comfort as a Service: A New Paradigm for Residential Environmental Quality Control
Authors: Gómez-Romero Juan , Molina-Solana Miguel , Ros María , Ruiz M. Dolores , Martin-Bautista M. J.
Published: August 2018

This paper introduces the concept of Comfort as a Service (CaaS), a new energy supply paradigm for providing comfort to residential customers. CaaS takes into account the available passive and active elements, the external factors that affect energy consumption and associated costs, and occupants’ behaviors to generate optimal control strategies for the domestic equipment automatically. As a consequence, it releases building occupants from operating the equipment, which gives rise to a disruption of the traditional model of paying per consumed energy in favor of a model of paying per provided comfort. In the paper, we envision a realization of CaaS based on several technologies such as ambient intelligence, big data, cloud computing and predictive computing. We discuss the opportunities and the barriers of CaaS-centered business and exemplify the potential of CaaS deployments by quantifying the expected energy savings achieved after limiting occupants’ control over the air conditioning system in a test scenario.
Temporal Evolution and Influencing Factors of Energy Consumption and Related Carbon Emissions from the Perspective of Industrialization and Urbanization in Shanghai, China
Authors: Li Pingxing , Sun Wei
Published: August 2018

Improvements of manufacturability and living standard driven by industrialization and urbanization typically cause a spike in total energy consumption (TEC) and related carbon emissions (TCEM). However, there have been few comparative studies to include industrial and residential energy consumption (IEC and REC, respectively) and related carbon emissions (ICEM and RCEM, respectively). Since China is a major emerging industrial country wherein urbanization is still ongoing, the present study was conducted in an attempt to analyze the temporal evolution of China’s continued energy consumption and related carbon emissions regarding both industrialization and urbanization. The influencing factors of TCEM, RCEM and ICEM are determined via the log-mean divisia index (LMDI) model. The results showed that both TEC and TCEM gradually increased (apart from a slight decrease in 2014); REC and RCEM increased steadily with no sharp peak; while IEC and ICEM declined sharply. TCEM was positively affected by economic output, consumption level, and population size; the influence of consumption level became more and more significant. Per capita GDP and per capita expenditure were the most significant driving factors for RCEM, while industrial added value (IAV) was the main driving factor for ICEM. The temporal evolution and influencing factors of energy consumption and carbon emissions had stage-related characteristics in accordance with Shanghai’s three stages of development. The Shanghai case study provided a comprehensive understanding of energy consumption and related carbon emissions from the dual perspective of industrialization and urbanization.
Assessing Sustainable Food Systems Governance in EU’s Outermost Regions—The Case of the Azores in Portugal
Authors: Hernández Paola Andrea , Guimarães Maria Helena , Rivera Maria , Silva Emiliana
Published: August 2018

The European Union’s (EU) remote rural areas undergo unique organizational challenges to counteract geopolitical, economic, and environmental constraints and engage in a competitive global food market. A one size fits all recipe to mend specific issues has also proven inefficient and led policy-makers to acknowledge the importance of implementing sustainable landscape governance to promote rural development. This paper inquires what are the challenges and opportunities food systems must adopt in a sustainable landscape governance approach, based on a qualitative research work carried out in the Azores Region (Portugal) in 2016. Data was gathered via eleven semi-structured interviews to key stakeholders and participatory observation in six events related to the management of the Azores’ food system. A grounded theory method structured qualitatively research participants’ perceptions about the Region’s food regime. This analysis is hereby furthered according to the four criteria proposed by the sustainable landscape governance assessment method. Our results indicate the lack of coordination among actors, institutions and policies in the Azores Region could be counteracted by promoting inclusive participation and integrated knowledge to attain cohesive, sustainable, and efficient outcomes at the landscape level. The methodology has proven to be adequate and instrumental in identifying sustainable landscape governance issues in other food systems.
Car vs. Packaging—A First, Simple (Environmental) Sustainability Assessment of Our Changing Shopping Behaviour
Authors: Hischier Roland
Published: August 2018

Which way of purchasing your clothes results in the lowest environmental impacts: “running” into the next big city to “plunder” the various clothing stores, or searching through a plethora of online shops and ordering your next shirt directly to you at home? So far, no such comparison has been published. The aim of this study is to get a first basic idea of which of these two consumer choices is the more environmentally sustainable by assessing the potential environmental impacts related to one person’s annual purchases of clothing through a simplified life cycle assessment. The study shows that going to a nearby city for shopping is not necessarily worse compared to online purchasing. When a person uses their own car, travel from home to the city and back is responsible for a sizeable amount of the potential impacts. However, the potential impacts of travel are heavily influenced by the means of transport (i.e., use of public transport rather than personal car) and the frequency of shopping excursions over the year. Overall, the potential impacts per single clothing item purchased could be in a similar range for both means of purchase.
Farmers’ Perception of Water Quality and Risks in the Mashavera River Basin, Georgia: Analyzing the Vulnerability of the Social-Ecological System through Community Perceptions
Authors: Withanachchi Sisira S. , Kunchulia Ilia , Ghambashidze Giorgi , Al Sidawi Rami , Urushadze Teo , Ploeger Angelika
Published: August 2018

Competing natural resources usage that leads to dramatic land use changes can threaten the balance of a social-ecological system. When this is the case, communities are directly exposed to the negative consequences of those land use changes. The Mashavera River Basin is considered one of the hotspots of environmental pollution in Georgia. This is of importance for public health because the food production from this basin meets a substantial proportion of the country’s food demand. The farmers’ perception of the water quality and their perceived risks to the economy, health, and lifestyle reflect the status of the environmental and social conditions. The inclusion of farmers’ risk perceptions is an important stage of water quality governance that could enable active civic participation. The approach of this research study was the convergence model in the triangular design of the mixed method approach. As part of the social data, the research study was conducted with a survey of 177 households, for which agriculture was either a main or partial source of income. A few focus group discussions were also conducted. A binary logistic regression analysis was employed as the main method for the analysis. The results from the pollution load index (PLI) were used as the supportive data to verify some geospatial hypotheses. We found that aesthetic attributes (i.e., color changes observed in the river) and the source of the water contamination (i.e., mining sites) were the main predictor variables for a perceived risk to water quality, health, and livelihoods. The people who work in agriculture as the main income source had more concern about their ability to sell their agricultural products as a result of water contamination in the river, compared with people for whom agriculture is a secondary source of income or for self-consumption. Age, amount of land, years of agricultural experience, and the source of water supply for agriculture did not have a significant effect on any of the risk perception or water quality perception models. The results indicate that the health risk is perceived more strongly in areas with more heavily contaminated water compared to less polluted areas. We propose that conducting a public risk perception assessment is an ideal means to detect people’s concerns regarding water quality governance for future risk analysis in Georgia. Another recommendation of this study is an integrated model of risk assessment that combines the results from a public risk perception assessment and a technical assessment. The benefits of such an integrated assessment include finding new hazard-sensitive areas for further analysis, the possibility to cross-check data for verification, communal communication of hazardous conditions by utilizing local knowledge, and the direct participation of the community in monitoring risks.
Recent Sustainability Performance in China: Strength-Weakness Analysis and Ranking of Provincial Cities
Authors: Zheng Bohong , Bedra Komi Bernard
Published: August 2018

Since the 1992 United Nations Conference on environment and development held in Rio de Janeiro (Brazil) and the adoption by China State Council in March 1994 of the “China Agenda 21”, sustainability has become a major issue in China urbanization policies. After more than two decades of development practice with a breakneck speed of urbanization, how sustainable is the recent development process in China? This paper combines the frameworks of Cities Prosperity Index (CPI) and Sustainable Cities Index (SCI) and propose a China Urban Sustainability Index by Fuzzy Evaluation (CUSI-FE) as a monitoring tool in the light of the UN Sustainable Development Goals (SDGs). With 5 years data covering 51 indicators, the model is tested to assess the performance of provincial cities in China during 5-years period from 2012 to 2016 (the year of the adoption of the SDGs). The results reveal that the overall sustainability level in China is barely average with lower performances in environmental sustainability. Indeed, a strength/weakness analysis, coupled with sensitivity analysis shows that the economic productivity and the large infrastructure development have had a strong energy cost and a sensible impact on environmental quality. Sustainable energy measures and industrial waste recycling are more likely to improve the sustainability of the cities, while the GDP growth will continue to contribute significantly also.
Application of Blockchain Technology in Sustainable Energy Systems: An Overview
Authors: Wu Jiani , Tran Nguyen Khoi
Published: August 2018

The Energy Internet has become a hot topic for the integration of sustainable energies. However, as a result, there are numerous sustainable energy forms and participants, the system is extremely complex, and some key issues are difficult to overcome, such as the control and management of distributed sustainable energy forms. On the other hand, blockchain technology consists of distributed data storage, peer-to-peer transmission, a consensus mechanism, encryption algorithms, and smart contracts. Applying the technical advantages of the blockchain to the Energy Internet can solve many of the problems that hinder its development. The purpose of this paper is to review the development of blockchain and the Energy Internet, and provide some references for the possible applications of blockchain technology to the Energy Internet. Firstly, the definition and characteristics of blockchain and the Energy Internet are introduced in detail. Secondly, the compatibility of the two is analyzed. Then, several application scenarios of blockchain in the Energy Internet are put forward. Finally, the challenges that still exist when applying the current blockchain technology to the Energy Internet are analyzed.
Trends in Taxi Use and the Advent of Ridehailing, 1995–2017: Evidence from the US National Household Travel Survey
Authors: Conway Matthew Wigginton , Salon Deborah , King David A.
Published: August 2018

The advent of ridehailing services such as Uber and Lyft has expanded for-hire vehicle travel. We use data from the 2017 National Household Travel Survey (NHTS) to investigate the extent of this expansion in the United States. We report changes in the for-hire vehicle market since ridehailing services became available and statistically estimate the determinants of ridehailing use. From 2009–2017, the for-hire vehicle market share doubled. While for-hire vehicles still only account for 0.5% of all trips, the percent of all Americans who use ridehailing in any given month is nearly 10%. Within the for-hire vehicle market, this trend of growth has not been uniformly distributed across demographic groups or geographies; it has been greater in mid-sized and large cities, and among younger individuals and wealthier households. This suggests that understanding the equity implications of ridehailing is an important avenue for research. Multivariate analysis provides evidence that both transit and nonmotorized transport use are correlated with ridehailing use, that ridehailing has a negative relationship with vehicle ownership, and that residents of denser areas have higher ridehailing use. Given the rapid growth of ridehailing, it has become important for cities to include for-hire vehicles in their planning going forward. These NHTS data provide a starting point, but more detailed and frequent data collection is needed to fully understand this many-faceted, rapidly-changing market.
The Pandemic Threat of Emerging H5 and H7 Avian Influenza Viruses
Authors: Sutton Troy C.
Published: August 2018

The 1918 H1N1 Spanish Influenza pandemic was the most severe pandemic in modern history. Unlike more recent pandemics, most of the 1918 H1N1 virus’ genome was derived directly from an avian influenza virus. Recent avian-origin H5 A/goose/Guangdong/1/1996 (GsGd) and Asian H7N9 viruses have caused several hundred human infections with high mortality rates. While these viruses have not spread beyond infected individuals, if they evolve the ability to transmit efficiently from person-to-person, specifically via the airborne route, they will initiate a pandemic. Therefore, this review examines H5 GsGd and Asian H7N9 viruses that have caused recent zoonotic infections with a focus on viral properties that support airborne transmission. Several GsGd H5 and Asian H7N9 viruses display molecular changes that potentiate transmission and/or exhibit ability for limited transmission between ferrets. However, the hemagglutinin of these viruses is unstable; this likely represents the most significant obstacle to the emergence of a virus capable of efficient airborne transmission. Given the global disease burden of an influenza pandemic, continued surveillance and pandemic preparedness efforts against H5 GsGd and Asian lineage H7N9 viruses are warranted.
β-Defensins Coordinate In Vivo to Inhibit Bacterial Infections of the Trachea
Authors: Ryan Lisa Kathleen , Wu Jichuan , Schwartz Kyell , Yim Sunghan , Diamond Gill
Published: August 2018

β-defensins are predicted to play an important role in innate immunity against bacterial infections in the airway. We previously observed that a type III-secretion product of Bordetella bronchiseptica inhibits the NF-κB-mediated induction of a β-defensin in airway epithelial cells in vitro. To confirm this in vivo and to examine the relative roles of other β-defensins in the airway, we infected wild-type C57BL/6 mice and mice with a deletion of the mBD-1 gene with B. bronchiseptica wild-type strain, RB50 and its mutant strain lacking the type III-secretion system, WD3. The bacteria were quantified in the trachea and the nasal tissue and mRNA levels of mouse β-defensin-3 (mBD-3) were assessed after 24 h. Infection with the wild-type bacterial strain resulted in lower mBD-3 mRNA levels in the trachea than in mice infected with the type III-deficient strain. Furthermore, we observed an increase in bacterial numbers of RB50 only in the tracheas of mBD-1-deficient mice. Neutrophils were also more abundant on the trachea in RB50 infected WT mice but not in the bronchiolar lavage fluid (BAL), compared with WD3 infected WT and mBD-1−/− mice, indicating that the coordination of β-defensin chemotactic effects may be confined to tracheal epithelial cells (TEC). RB50 decreased the ability of mice to mount an early specific antibody response, seven days after infection in both WT and mBD-1−/− mice but there were no differences in titers between RB50-infected WT and mBD-1−/− mice or between WD3-infected WT and mBD-1−/− mice, indicating mBD-1 was not involved in induction of the humoral immune response to the B. bronchiseptica. Challenge of primary mouse TEC in vitro with RB50 and WD3, along with IL-1β, further corroborated the in vivo studies. The results demonstrate that at least two β-defensins can coordinate early in an infection to limit the growth of bacteria in the trachea.
First-Principles Study on the Migration of Heavy Metal Ions in Ice-Water Medium from Ulansuhai Lake
Authors: Sun Chi , Li Changyou , Liu Jianjun , Shi Xiaohong , Zhao Shengnan , Wu Yong , Tian Weidong
Published: August 2018

Energy is a fundamental driver that causes material movement. It is important to discover changes in energy by studying the internal mechanism of pollutant migration between system components during the freezing process. To explore the migration mechanism of heavy metal ions (HMIs) from ice to water in a lake, we carried out a laboratory freezing experiment and simulated the distribution and migration of HMIs (Fe, Cu, Mn, Zn, Pb, Cd, and Hg) under different conditions. Then, we analyzed the use of energy by first-principle calculations. The results showed that HMIs are more stable in an aqueous environment than in an ice environment. For the same HMI, the binding energy in water is smaller than that in ice. Hence, the HMIs migrated from ice to water as the lake was freezing. The ability of different kinds of heavy metals to migrate from ice to water is related to their binding energy in ice. The concentrations of HMIs in ice are positively correlated with their binding energies. This study investigated the migration characteristics and mechanisms of HMIs in the process of lake freezing.
Conscience et discours européens des exilés espagnols
Authors: Bachoud Andrée , Dreyfus-Armand Geneviève
Published: August 2018

Malgré leur déception devant l'attitude des démocraties européennes pendant la Guerre civile et vis-à-vis de Franco, l'Europe demeure pour les nationalistes basques et catalans un élément stratégique dans leur revendication du respect des nationalités. A partir de l'immédiate après-guerre, la construction européenne sera également pour des socialistes, des libéraux, des républicains et les quelques monarchistes exilés, un axe de plus en plus présent dans leur combat antifranquiste. La première jonction d'importance entre les exilés et les opposants de l'intérieur s'effectue, à Munich en 1962, dans le cadre d'une rencontre européenne.
Introduction : Pour une histoire comparée des politiques publiques en France et en Argentine
Authors: Gonzalez Bernaldo Pilar
Published: August 2018

L'article présente d'abord le programme d'histoire comparée des migrations en France et en Argentine entre 1780-1960, à partir de l'analyse de trois groupes migratoires : Espagnols, Italiens et Portugais. Il expose les résultats d'une première rencontre scientifique sur «Les politiques publiques des États face au problème migratoire », dont les travaux sont publiés dans ce numéro de la revue «Exils et Migrations ». Il dégage, enfin, certaines variables qui invitent à la comparaison : les moyens dont disposent les États pour mener à bien leurs politiques, les impératifs de ces politiques, et les acteurs qui interviennent dans leur fixation. Dans chaque cas est présenté un éventail de questions qui renvoient à une indispensable étude comparée du fonctionnement de l'État et de la relation qu'il établit avec la société dans les deux pays. Le travail conclut sur deux points centraux qui traversent tous ces travaux : la question de l'efficacité de l'État qui pose le problème de la «rationalité » qu'on veut prêter à ces politiques, et celle des modèles identitaires de nation.
Novel photochemical reactions of carbocyclic diazodiketones without elimination of nitrogen – a suitable way to N-hydrazonation of C–H-bonds
Authors: Rodina Liudmila L , Azarova Xenia V , Medvedev Jury J , Semenok Dmitrij V , Nikolaev Valerij A
Published: August 2018

The sensitized photoexcitation of 2-diazocyclopentane-1,3-diones in the presence of THF leads to the insertion of the terminal N-atom of the diazo group into the α-С–Н bond of THF, producing the associated N-alkylhydrazones in yields of up to 63–71%. Further irradiation of hydrazones derived from furan-fused tricyclic diazocyclopentanediones culminates in the cycloelimination of furans to yield 2-N-(alkyl)hydrazone of cyclopentene-1,2,3-trione. By contrast, the direct photolysis of carbocyclic diazodiketones gives only Wolff rearrangement products with up to 90–97% yield.
Cobalt bis(acetylacetonate)–tert-butyl hydroperoxide–triethylsilane: a general reagent combination for the Markovnikov-selective hydrofunctionalization of alkenes by hydrogen atom transfer
Authors: Ma Xiaoshen , Herzon Seth B
Published: August 2018

We show that cobalt bis(acetylacetonate) [Co(acac)2], tert-butyl hydroperoxide (TBHP), and triethylsilane (Et3SiH) constitute an inexpensive, general, and practical reagent combination to initiate a broad range of Markovnikov-selective alkene hydrofunctionalization reactions. These transformations are believed to proceed by cobalt-mediated hydrogen atom transfer (HAT) to the alkene substrate, followed by interception of the resulting alkyl radical intermediate with a SOMOphile. In addition, we report the first reductive couplings of unactivated alkenes and aryldiazonium salts by an HAT pathway. The simplicity and generality of the Co(acac)2–TBHP–Et3SiH reagent combination suggests it as a useful starting point to develop HAT reactions in complex settings.
The spider fauna from Uruguay River islands: understanding its role in a biological corridor
Authors: Laborda Álvaro , Montes de Oca Laura , Pérez-Miles Fernando , Useta Gonzalo , Simó Miguel
Published: August 2018

Biological corridors are connections which link habitats in a regional scale, allowing the gene flow between populations. The Uruguay River comprises riverside and insular riparian forests along subtropical to temperate zones passing through different biogeographic provinces. The aim of this study was to characterise the spider fauna from the Uruguay River islands highlighting their connection role for the spider community of riparian forest. Spiders were studied from surveys in a fluvial island of the southern course of the river with nine campaigns being carried out from September 2007 to September 2009. Three complementary collecting methods were used: G-Vac, night hand collecting and pitfall traps. A total of 58 samples were taken in each campaign. A total of 33 families, 145 species/morphospecies and 8 guilds were registered. Theridiidae and space web weavers showed the highest abundance and species richness. Web weavers were predominant in the spider community evidencing the importance of the forest vegetation heterogeneity in spider diversity. Fifteen species have been recorded for the first time for Uruguay. Additional data of previous surveys in the northern islands of the river were analysed and compared. Several species confirm the role of the Uruguay River as a biological corridor from the upper to lower course of the river. The riparian forests from the islands constitute a southernmost intromission of Paranaense biota between Chaco and Pampa regions along the river. The results obtained are an important input for the conservation of these areas. Knowing the biodiversity, as well as its dynamics and the flow of biota that exists in these environments, would allow planning the management from a regional point of view.
Sobre la identidad de Calomicrus fallax (Joannis, 1865), con descripción de una nueva especie de Calomicrus ampliamente distribuida por España y Portugal, y notas sobre las especies ibéricas (Coleoptera, Chrysomelidae, Galerucinae)
Authors: Vela José Miguel
Published: August 2018

Se redescribe Calomicrus fallax (Joannis, 1865), y su distribución queda limitada a Túnez y Argelia. Se describe una nueva especie de Portugal y España, Calomicrus ibericus sp. nov., históricamente confundida con C. fallax, y se evidencian las diferencias entre ambas. Se ofrece una lista geográfica de las especies ibéricas de Calomicrus Dillwyn, 1829, y dos especies anteriormente combinadas en este género, C. espanoli (Codina, 1963) y C. pinicola (Duftschmid, 1825), son transferidas a Euluperus Weise, 1886. Se propone una clave dicotómica para separar las especies ibéricas de Calomicrus y Euluperus, y se muestran fotografía a color de los habitus de las mismas.
Sinterability of 8 mol% Yttria Stabilized Zirconia
Authors: Selvaraj Tinesha , Johar Banjuraizah , Khor S.F. , Mohd Zainol M.N.
Published: August 2018

The sintering behaviour of low cost 8 mol% yttria stabilized zirconia powders has been studied. The effect of sintering holding time of the sintered granulated and milled 8YSZ were determined using density measurements, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The elemental composition, particle size and morphology of the as-received 8YSZ powder and proceed for milling was investigated. 48 hours of ball milling on granulated 8YSZ resulted rises in specific surface area and sintered at 1550°C with the various period of time (4, 5, 6 and 7 hours). The milled 8YSZ sample with 5h sintering holding period coded as F5, sintering activity improved and the relative density came up to 98.3%. But then, granulated 8YSZ achieved only 62.7% with 5 hours holding time. Crystal structure analysis for milled 8YSZ powder consists of 59.6% of cubic ZrO2 phase, 40.1% of tetragonal ZrO2 and 0.3% of monoclinic ZrO2. Meanwhile, granulated 8YSZ indicated low content in cubic ZrO2 but high amount in monoclinic ZrO2 phase. In brief, low cost 8YSZ reached higher densification of 98% successfully.
TiC-Coated Carbon Black Particles as a Bioactive Ceramic Compound for Application of Bone Tissue Engineering
Authors: Soe Hnin Nandar , Khangkhamano Matthana , Songkert Supaporn , Meesane Jirut , Kokoo Rungrote
Published: August 2018

Titanium carbide-coated carbon black particles (TCBs) were synthesized via reaction of metallic titanium powder with carbon black powder in a molten potassium chloride at 900°C for 4 hours in argon atmosphere to study their biological properties to be used as a bioactive ceramic compound for bone formation. Phase compositions and morphologies were characterized by electron diffraction spectroscopy (EDS) and scanning electron microscope (SEM). Core-shell structure was examined by transmission electron microscope (TEM). Biofunctionalities were considered by cell proliferation and protein synthesis. titanium and carbon peak were found, on an EDS curve of the as-synthesized powder, indicating the complete reaction. The shape and size of as-synthesized powder and as-received carbon black powder are similar, as it is noticed the template growth mechanism of the reaction. However, the surface morphology of as-synthesized powder is different because of its rough surface. Core-shell structure of the as-synthesized powder was revealed by TEM that an ultra-thin layer of titanium carbide was successfully coated on a carbon black particle. Biological testing showed, as compared to a control, a significant enhancement in cell proliferation and protein synthesis of the as-synthesized TCBs suggesting a good candidate as a bioactive compound for biomedical applications.
Synthesis of WSi2-W5Si3 Intermetallic Alloy via Self-Propagating High Temperature Synthesis
Authors: Maung Si Thu Myint , Chanadee Tawat , Niyomwas Sutham
Published: August 2018

Intermetallic alloy of tungsten silicide (WSi2-W5Si3) was synthesized by self-propagating high temperature synthesis (SHS) from the reactant of tungsten oxide (WO3) and silicon lump (Si) using magnesium (Mg) as fuel. The standard Gibbs energy minimization method was used to calculate the equilibrium composition of the possible reacting species. The as-SHS products were characterized by X-ray diffraction (XRD) technique. The magnesiothermic reaction process successfully synthesized dense of WSi2-W5Si3 intermetallic alloy. According to the experimental results, it can be proposed that the reaction also promotes the phase separation between alloy and oxide slag of the product.
Two-Stepped Synthesis of High Performance Reduced Graphene Oxide Antenna
Authors: Jamlos M.A. , Jamlos M.F. , Ismail A.H.
Published: August 2018

The paper presents a two-stepped technique to synthesize the Reduced Graphene Oxide (RGO). RGO is a single layer structure of carbon without presence of oxygen group with high level of conductivity (3.38 × 105 s/m). The synthesized graphene is used on low permittivity substrate to realize high performance RGO microstrip patch antenna. The antenna operates in ultra-wide band frequency range from 2.5 GHz to 12.2 GHz with gains between 5.5dB and 14.5dB. Low profile and small size (90 mm × 45 mm) makes the antenna suitable for integration.
Microwave and Electrical Properties of Zr-Doped SrTiO3 for Dielectric Resonator Antenna Application
Authors: Muhamad Norhizatol Fashren , Osman Rozana Aina Maulat , Idris Mohd Sobri , Jamlos Faizal , Hambali Nor Azura Malini Ahmad
Published: August 2018

Present investigation provides experimental studies on cylindrical dielectric resonator antennas (CDRAs) fabricated from SrTi1-xZrxO3 ceramic with different substitution of Zr in place of Ti for (0 ≤ x ≤1). Ceramic powder were prepared using conventional solid state reaction method. X-ray Diffraction exposes physical properties Zr-doped SrTiO3 which exhibit phase transition from cubic, tetragonal to orthorhombic phase. The electrical properties such as dielectric constant (εr) and dielectric loss (tan δ) were studied in variation of temperatures and frequencies. At room temperature the dielectric constant decreased from 240 to 21 with increase of Zr content however the amazing result was obtained for multiband antenna by Zr content. The dielectric loss obtain shows very low loss value roughly below 0.07 for all samples. The variations of return loss, resonance frequency and bandwidth of CDRAs at their respective resonant frequencies are studied experimentally.
Spontaneous Tin (Sn) Whisker Growth from Electroplated Tin and Lead-Free Tin Alloys Coatings: A Short Review
Authors: Hashim Aimi Noorliyana , Mohd Salleh Mohd Arif Anuar
Published: August 2018

Since the environmental regulations of Reduction of Hazardous Substances (RoHS) directive came into effect in Europe and Asia on July 1, 2006, requiring the removal of any lead (Pb) content from the electronics industry, the issue of tin (Sn) whisker growth from pure Sn and SnPb-free alloys has become one of the most imperative issues that need to be resolved. Moreover, with the increasing demand for electronics miniaturization, Sn whisker growth is a severe threat to the reliability of microelectronic devices. Sn whiskers grow spontaneously from an electrodeposited tin coating on a copper substrate at room temperature, which can lead to well-documented system failures in electronics industries. The Sn whisker phenomenon unavoidably gives rise to troubles. This paper briefly reviews to better understand the fundamental properties of Sn whisker growth and at the same time discover the effective mitigation practices for whisker growth in green electronic devices. It is generally accepted that compressive stress generated from the growth of Cu6Sn5 intermetallic compound (IMC) is the primary driving force for Sn whisker growth during room temperature storage. It is, therefore, important to determine that the relationship between IMC growth and Sn whisker growth. Reduction of stress in the IMC layer can therefore reduce the driving force for whisker formation and be used as a means for whisker mitigation. To date, there are no successful methods that can suppress the growth of Sn whisker as efficient as Pb addition. It is hoped that the Sn whisker growth mechanisms are understood better in the future, with better measuring and monitoring methodologies and systems being developed, the real solutions may be eventually developed to eliminate or mitigate the Sn whisker problems of green reliability lead-free electronic assemblies.
Microstructure, Interfacial IMC and Wettability of Sn-0.7Cu-xZn Solder Alloy
Authors: Ramli Mohd Izrul Izwan , Mohd Salleh Mohd Arif Anuar , Ibrahim I.N.A. , Said Rita Mohd
Published: August 2018

In this study, the effect of Zinc (Zn) addition on microstructure, interfacial IMC and wettability properties of Sn-0.7Cu lead free solder alloy was investigated. The addition of 0.5, 1.0 and 1.5 wt.% Zn into Sn-0.7Cu was developed by using conventional casting method. The result revealed that the addition of Zn has refined the β-Sn phase. The thickness of interfacial IMC decreased with 0.5 wt.% and 1.0 wt.% Zn addition but increased after 1.5 wt.% of Zn was added. The wettability of Sn-0.7Cu also improved by the Zn addition. It can be concluded that a small amount of Zn addition up to 1.0 wt.% decreased the thickness of IMC and improved the wettability. However, when 1.5 wt.% Zn was added, the interfacial IMC and wettability become worse.
Influence of Non-Metallic Particles Addition on Wettability, Intermetallic Compound Formation and Microhardness of Sn-0.7Cu Lead Free Solder Paste
Authors: Zaimi N.S. Mohamad , Mohd Salleh Mohd Arif Anuar , Al Bakri A.M. Mustafa , Said Rita Mohd , Saud Norainiza
Published: August 2018

A non metallic reinforcement has attracted most of the worldwide researchers to enhance solder performance. Silicon carbide (SiC) particle is a semiconductor which had been used as a non metallic reinforcement in this research study.The fabrication of Sn-0.7Cu lead free solder paste was done by mixing the solder powder with flux. Then, Sn-0.7Cu/SiC composite solder paste was prepared by mixing solder powder, flux and various weight percentage (wt%) of SiC. The amount of SiC particles added was 0, 0.25, 0.50, 0.75 and 1.0 wt%. The influence of SiC addition was analyzed based on its wettability, IMC layer formation and microhardness properties. The addition of SiC particles had decreased the contact angle as well as thinner the IMC layer. The morphology of IMC layer changed from scallop like shape to combination of scallop and planar like shape with the addition of SiC particle. Apart from that, the microhardness was enhanced with addition of SiC particle into Sn-0.7Cu lead free solder paste.
Enhancement of Microstructural and Physical Properties of Sn-0.7Cu Lead-Free Solder with the Addition of SiC Particles
Authors: Mahim Z. , Abdul Razak Nurul Razliana , Mohd Salleh Mohd Arif Anuar , Saud Norainiza
Published: August 2018

Nowadays, composite solder has gained researcher’s attention due to its promising improvement in physical and mechanical properties for lead-free solder. To improve the properties of Sn-0.7Cu (SnCu): the promising lead-free candidate, addition of silicon carbide (SiC) as a reinforcement was used into this study. However, its limitation on solderability as compared with SnAgCu (SAC) make it not an attractive alternative lead-free solder. This study was carried out to investigate the effect of SiC particle on microstructure evolution and physical properties of SnCu based solder alloys. SnCu-SiC composite solders were synthesized by powder metallurgy method (PM), which consists of several processes such as mechanical blending, compaction and sintering. Five different weight percentages of SiC particle; 0.00, 0.25, 0.50, 0.75 and 1.00 were mechanically blended with SnCu lead-free solder. The result shows that the addition of SiC particle has decreased the β-Sn area and refined the microstructure of composite solder. In addition, the improvement in microhardness of composite was achieved.