bluuebunny/crossref_metadata_2025 huggingface dataset:
A Causal Analysis of Life Expectancy at Birth. Evidence from Spain
Authors: Martín Cervantes Pedro Antonio , Rueda López Nuria , Cruz Rambaud Salvador
Published: July 2019

Background: From a causal point of view, there exists a set of socioeconomic indicators concerning life expectancy. The objective of this paper is to determine the indicators which exhibit a relation of causality with life expectancy at birth. Methods: Our analysis applies the Granger causality test, more specifically its version by Dumitrescu–Hurlin, starting from the information concerning life expectancy at birth and a set of socioeconomic variables corresponding to 17 Spanish regions, throughout the period 2006–2016. To do this, we used the panel data involving the information provided by the Spanish Ministry of Health, Consumer Affairs and Social Welfare (MHCSW) and the National Institute of Statistics (NIS). Results: Per capita income, and the rate of hospital beds, medical staff and nurses Granger-cause the variable “life expectancy at birth”, according to the Granger causality test applied to panel data (Dumitrescu–Hurlin’s version). Conclusions: Life expectancy at birth has become one of the main indicators able to measure the performance of a country’s health system. This analysis facilitates the identification of those factors which exhibit a unidirectional Granger-causality relationship with life expectancy at birth. Therefore, this paper provides useful information for the management of public health resources from the point of view of the maximization of social benefits.
Atrial Natriuretic Peptide: A Molecular Target of Novel Therapeutic Approaches to Cardio-Metabolic Disease
Authors: Cannone Valentina , Cabassi Aderville , Volpi Riccardo , Burnett John C.
Published: July 2019

Atrial natriuretic peptide (ANP) is a cardiac hormone with pleiotropic cardiovascular and metabolic properties including vasodilation, natriuresis and suppression of the renin-angiotensin-aldosterone system. Moreover, ANP induces lipolysis, lipid oxidation, adipocyte browning and ameliorates insulin sensitivity. Studies on ANP genetic variants revealed that subjects with higher ANP plasma levels have lower cardio-metabolic risk. In vivo and in humans, augmenting the ANP pathway has been shown to exert cardiovascular therapeutic actions while ameliorating the metabolic profile. MANP is a novel designer ANP-based peptide with greater and more sustained biological actions than ANP in animal models. Recent studies also demonstrated that MANP lowers blood pressure and inhibits aldosterone in hypertensive subjects whereas cardiometabolic properties of MANP are currently tested in an on-going clinical study in hypertension and metabolic syndrome. Evidence from in vitro, in vivo and in human studies support the concept that ANP and related pathway represent an optimal target for a comprehensive approach to cardiometabolic disease.
Distinct Profiles of Cell-Free MicroRNAs in Plasma of Veterans with Post-Traumatic Stress Disorder
Authors: Lee Min , Baxter David , Scherler Kelsey , Kim Taek-Kyun , Wu Xiaogang , Abu-Amara Duna , Flory Janine , Yehuda Rachel , Marmar Charles , Jett Marti , Lee Inyoul , Wang Kai , Hood Leroy
Published: July 2019

Dysregulation of circulating microRNAs (miRNAs) in body fluids has been reported in psychiatric disorders such as schizophrenia, bipolar disorder, major depressive disorder, and post-traumatic stress disorder (PTSD). Recent studies of various diseases showed that extracellular vesicles (EV) in body fluids can provide different spectra of circulating miRNAs and disease-associated signatures from whole fluid or EV-depleted fraction. However, the association of miRNAs in EVs to PTSD has not been studied. In this study, we performed a comprehensive profiling of miRNAs in whole plasma, extracellular vesicles (EV) and EV-depleted plasma (EVD) samples collected from combat veterans with PTSD and matched controls by utilizing a next-generation sequencing (NGS) platform. In total, 520 circulating miRNAs were quantified from 24 male Iraq and Afghanistan combat veterans with (n = 12) and without (n = 12) PTSD. The overall miRNA profiles in whole plasma, EV and EVD fractions were different and miRNAs affected by PTSD were also distinct in each sample type. The concentration changes of miR-203a-3p in EV and miR-339-5p in EVD were confirmed in an independent validation cohort that consisted of 20 veterans (10 with and 10 without PTSD) using qPCR. The target genes of these two miRNAs were involved in signaling pathways and comorbid conditions associated with PTSD (e.g., neurotransmitter systems such as dopaminergic and serotonergic signaling, inflammatory response, and cardiovascular diseases). Our findings suggest that PTSD may have different impacts on miRNAs encapsulated in vesicles and outside of vesicles. Further studies using larger samples are needed to evaluate the utility of these miRNAs as diagnostic biomarkers for PTSD.
Sources of the Measurement Error of the Impact Pressure in Sloshing Experiments
Authors: Kim Dong Hwi , Kim Eun Soo , Shin Sung-chul , Kwon Sun Hong
Published: July 2019

Sloshing experiments have increasingly received academic attention. Understanding the measurement errors in the sloshing impact pressures is an important parts of the sloshing experiments since these errors, which arise from experimental conditions, affect the subsequent results. As part of the research on the sources of the measurement errors, focused on the effects of surface conditions of pressure sensors on the measurement of impact pressures. Thirty-six integrated circuit piezoelectric pressure sensors were placed on the upper surfaces of a two-dimensional tank to measure the sloshing impact pressures under surge or pitch motions. For each motion, the experimental conditions were divided in two based on whether the surfaces of the sensors were dry or wet. The peak pressures of each test were measured as twenty repeated experiments to ensure reliability. The flow in the tank was visualized using a high-speed camera to observe and analyze macroscopic and microscopic phenomena along the sensor surface. Thermal shock effects were confirmed by varying the experimental temperature and that of the sensor surface. The effects of the wet surface and droplets formed on the sensor surface on pressure measurements are discussed.
Hydrogen/Deuterium Dynamics in Hydroxyl Salts Co2(OH)3Br/Co2(OD)3Br Revealed by Muon Spin Relaxation
Authors: Xu Xing-Liang , Zheng Xu-Guang , Watanabe Isao
Published: July 2019

The temperature-dependent dynamics of the hydrogen/deuterium atoms in geometrically frustrated magnets Co2(OH)3Br and its deuterated form Co2(OD)3Br were investigated by muon spin relaxation (μSR). The deuterium atoms in Co2(OD)3Br were found to be rapidly fluctuating at high temperatures, which should be arising as a quantum atomic effect due to the small mass of deuterium, then they drastically slowed down toward Tc = 250 K where a broad anomaly appeared in the dielectric response, and finally became quasi-static at around 180 K. Meanwhile, the hydrogen atoms in Co2(OH)3Br also exhibited a two-step slowing at ~240 K and ~180 K, respectively. The revealed properties in Co2(OH)3Br/Co2(OD)3Br are reminiscent of relaxor-type ferroelectrics. The present study suggested the effectiveness of the μSR technique on revealing the hydrogen/deuterium (H/D) dynamics in Co2(OH)3Br/Co2(OD)3Br. Furthermore, magnetic coupling was found to be existing at high temperatures in this system. This work provides clear evidence to the mechanism of ferroelectric responses in the hydroxyl salts, i.e., the slowing of protons (deuterium ions) is directly related to the newly revealed ferroelectricity.
Lithium Attachment to C60 and Nitrogen- and Boron-Doped C60: A Mechanistic Study
Authors: Chen Yingqian , Cho Chae-Ryong , Manzhos Sergei
Published: July 2019

Fullerene-based materials including C60 and doped C60 have previously been proposed as anodes for lithium ion batteries. It was also shown earlier that n- and p-doping of small molecules can substantially increase voltages and specific capacities. Here, we study ab initio the attachment of multiple lithium atoms to C60, nitrogen-doped C60 (n-type), and boron doped C60 (p-type). We relate the observed attachment energies (which determine the voltage) to changes in the electronic structure induced by Li attachment and by doping. We compare results with a GGA (generalized gradient approximation) functional and a hybrid functional and show that while they agree semi-quantitatively with respect to the expected voltages, there are qualitative differences in the electronic structure. We show that, contrary to small molecules, single atom n- and p-doping will not lead to practically useful modulation of the voltage–capacity curve beyond the initial stages of lithiation.
Quantification of Uncertainty and Best Practice in Computing Interfacial Curvature from Complex Pore Space Images
Authors: Akai Takashi , Lin Qingyang , Alhosani Abdulla , Bijeljic Branko , Blunt Martin
Published: July 2019

Recent advances in high-resolution three-dimensional X-ray CT imaging have made it possible to visualize fluid configurations during multiphase displacement at the pore-scale. However, there is an inherited difficulty in image-based curvature measurements: the use of voxelized image data may introduce significant error, which has not—to date—been quantified. To find the best method to compute curvature from micro-CT images and quantify the likely error, we performed drainage and imbibition direct numerical simulations for an oil/water system on a bead pack and a Bentheimer sandstone. From the simulations, local fluid configurations and fluid pressures were obtained. We then investigated methods to compute curvature on the oil/water interface. The interface was defined in two ways; in one case the simulated interface with a sub-resolution smoothness was used, while the other was a smoothed interface extracted from synthetic segmented data based on the simulated phase distribution. The curvature computed on these surfaces was compared with that obtained from the simulated capillary pressure, which does not depend on the explicit consideration of the shape of the interface. As distinguished from previous studies which compared an average or peak curvature with the value derived from the measured macroscopic capillary pressure, our approach can also be used to study the pore-by-pore variation. This paper suggests the best method to compute curvature on images with a quantification of likely errors: local capillary pressures for each pore can be estimated to within 30% if the average radius of curvature is more than 6 times the image resolution, while the average capillary pressure can also be estimated to within 11% if the average radius of curvature is more than 10 times the image resolution.
The Use of the Acoustic Emission Method to Identify Crack Growth in 40CrMo Steel
Authors: Krampikowska Aleksandra , Pała Robert , Dzioba Ihor , Świt Grzegorz
Published: July 2019

The article presents the application of the acoustic emission (AE) technique for detecting crack initiation and examining the crack growth process in steel used in engineering structures. The tests were carried out on 40CrMo steel specimens with a single edge notch in bending (SENB). In the tests crack opening displacement, force parameter, and potential drop signal were measured. The fracture mechanism under loading was classified as brittle. Accurate AE investigations of the cracking process and SEM observations of the fracture surfaces helped to determine that the cracking process is a more complex phenomenon than the commonly understood brittle fracture. The AE signals showed that the frequency range in the initial stage of crack development and in the further crack growth stages vary. Based on the analysis of parameters and frequencies of AE signals, it was found that the process of apparently brittle fracture begins and ends according to the mechanisms characteristic of ductile crack growth. The work focuses on the comparison of selected parameters of AE signals recorded in the pre-initiation phase and during the growth of brittle fracture cracking.
Alkali-Activated Cements for TES Materials in Buildings’ Envelops Formulated With Glass Cullet Recycling Waste and Microencapsulated Phase Change Materials
Authors: Giro-Paloma Jessica , Barreneche Camila , Maldonado-Alameda Alex , Royo Miquel , Formosa Joan , Fernández Ana Inés , Chimenos Josep M.
Published: July 2019

Within the thermal energy storage field, one of the main challenges of this study is the development of new enhanced heat storage materials to be used in the building sector. The purpose of this study is the development of alkali-activated cements (AACs) with mechanical properties to store high amounts of heat. These AACs incorporate wastes from industrial glass process as well as microencapsulated phase change materials (mPCMs) to improve the thermal inertia of building walls, and accordingly respective energy savings. The research presented below consists of the exhaustive characterization of different AACs formulated from some waste generated during the proper management of municipal waste used as precursor. In this case study, AACs were formulated with the waste generated during the recycling of glass cullet, namely ceramic, stone, and porcelain (CSP), which is embedding a mPCM. The addition of mPCM was used as thermal energy storage (TES) material. The mechanical properties were also evaluated in order to test the feasibility of the use of the new formulated materials as a passive TES system. The results showed that the AAC obtained from CSP (precursors) mixed with mPCMs to obtain a thermal regulator material to be implemented in building walls was reached successfully. The material developed was resistant enough to perform as insulating panels. The formulated materials had high storage capacity depending on the PCM content. The durability of the mPCM shell was studied in contact with alkaline medium (NaOH 4 M) and no degradation was confirmed. Moreover, the higher the content of mPCM, the lower the mechanical properties expected, due to the porosity increments with mPCM incorporation in the formulations.
Tersone A-G, New Pyridone Alkaloids from the Deep-Sea Fungus Phomopsis tersa
Authors: Chen Shan-Chong , Liu Zhao-Ming , Tan Hai-Bo , Chen Yu-Chan , Li Sai-Ni , Li Hao-Hua , Guo Heng , Zhu Shuang , Liu Hong-Xin , Zhang Wei-Min
Published: July 2019

Four phenylfuropyridone racemates, (±)-tersones A-C and E (1–3, 5), one phenylpyridone racemate, (±)-tersone D (4), one new pyridine alkaloid, tersone F (6), single new phenylfuropyridone, tersone G (7) and two known analogs 8 and 9 were isolated from the deep-sea fungus Phomopsis tersa. Their structures and absolute configurations were characterized on the basis of comprehensive spectroscopic analyses, single-crystal X-ray diffraction experiments, and electronic circular dichroism (ECD) calculations. Moreover, compounds 1–9 were evaluated for in vitro antimicrobial and cytotoxic activity. Compounds 5b and 8b exhibited antibacterial activity against S. aureus with the MIC value of 31.5 μg/mL, while compound 5b showed cytoxic activities against SF-268, MCF-7, HepG-2 and A549 cell lines with IC50 values of 32.0, 29.5, 39.5 and 33.2 μM, respectively.
Current Approaches to the Treatment of Gastric Varices: Glue, Coil Application, TIPS, and BRTO
Authors: Goral Vedat , Yılmaz Nevin
Published: July 2019

Gastric varices are less common than esophageal varices, and their treatment is quite challenging. Gastric varix bleedings (GVB) occur less frequently than esophageal varix (EV) bleedings and represent 10to 30% of all variceal bleedings. They are; however, more severe and are associated with high mortality. Re-bleeding may occur in 35to 90% of cases after spontaneous hemostasis. GV bleedings represent a serious clinical problem compared with esophageal varices due to their location. Sclerotherapy and band ligation, in particular, are less effective. Based on the anatomic site and location, treatment differs from EV and is categorized into two groups (i.e., endoscopic or radiologic treatment). Surgical management is used less frequently. Balloon-occluded retrograde transvenous obliteration (BRTO) and cyanoacrylate are safe but there is a high risk of re-bleeding. Portal pressure elevates following BRTO and leads to worsening of esophageal varix pressure. Other significant complications may include hemoglobinuria, abdominal pain, fever, and pleural effusion. Shock and atrial fibrillation are major complications. New and efficient treatment modalities will be possible in the future.
Improvement of Damping Property and Its Effects on the Vibration Fatigue in Ti6Al4V Titanium Alloy Treated by Warm Laser Shock Peening
Authors: Meng Xiankai , Zhao Yaomin , Lu Jinzhong , Huang Shu , Zhou Jianzhong , Su Chun
Published: July 2019

In order to increase the vibration life of Ti6Al4V titanium alloy, warm laser shock peening (WLSP) is used to improve the damping properties and thus decrease the vibration stress in this study. Firstly, the Ti6Al4V specimens are treated by WLSP at different treatment temperatures from 200 °C to 350 °C. Then the damping ratios of untreated and WLSPed samples are obtained by impact modal tests, and the improvement of damping properties generated by WLSP is analyzed by the microstructures in Ti6Al4V titanium alloy. Moreover, the finite element simulations are utilized to study the vibration amplitude and stress during the frequency response process. Finally, the vibration fatigue tests are carried out and the fatigue fracture morphology is observed by the scanning electron microscope. The results indicate that the damping ratios of WLSPed specimens increase with the increasing treatment temperatures. This is because elevated temperatures during WLSP can effectively increase the α phase colonies and the interphase boundaries, which can significantly increase the internal friction of materials. Moreover, due to the increasing material damping ratio, the displacement and stresses during vibration were both reduced greatly by 350 °C-WLSP, which can significantly decrease the fatigue crack growth rate and thus improve the vibration fatigue life of Ti6Al4V titanium alloy.
The Role of Hydrothermal Activity in the Formation of Karst-Hosted Manganese Deposits of the Postmasburg Mn Field, Northern Cape Province, South Africa
Authors: Fairey Brenton J. , Timmerman Martin J. , Sudo Masafumi , Tsikos Harilaos
Published: July 2019

The Postmasburg Manganese Field (PMF), Northern Cape Province, South Africa, once represented one of the largest sources of manganese ore worldwide. Two belts of manganese ore deposits have been distinguished in the PMF, namely the Western Belt of ferruginous manganese ores and the Eastern Belt of siliceous manganese ores. Prevailing models of ore formation in these two belts invoke karstification of manganese-rich dolomites and residual accumulation of manganese wad which later underwent diagenetic and low-grade metamorphic processes. For the most part, the role of hydrothermal processes and metasomatic alteration towards ore formation has not been adequately discussed. Here we report an abundance of common and some rare Al-, Na-, K- and Ba-bearing minerals, particularly aegirine, albite, microcline, banalsite, sérandite-pectolite, paragonite and natrolite in Mn ores of the PMF, indicative of hydrothermal influence. Enrichments in Na, K and/or Ba in the ores are generally on a percentage level for most samples analysed through bulk-rock techniques. The presence of As-rich tokyoite also suggests the presence of As and V in the hydrothermal fluid. The fluid was likely oxidized and alkaline in nature, akin to a mature basinal brine. Various replacement textures, particularly of Na- and K- rich minerals by Ba-bearing phases, suggest sequential deposition of gangue as well as ore-minerals from the hydrothermal fluid, with Ba phases being deposited at a later stage. The stratigraphic variability of the studied ores and their deviation from the strict classification of ferruginous and siliceous ores in the literature, suggests that a re-evaluation of genetic models is warranted. New Ar-Ar ages for K-feldspars suggest a late Neoproterozoic timing for hydrothermal activity. This corroborates previous geochronological evidence for regional hydrothermal activity that affected Mn ores at the PMF but also, possibly, the high-grade Mn ores of the Kalahari Manganese Field to the north. A revised, all-encompassing model for the development of the manganese deposits of the PMF is then proposed, whereby the source of metals is attributed to underlying carbonate rocks beyond the Reivilo Formation of the Campbellrand Subgroup. The main process by which metals are primarily accumulated is attributed to karstification of the dolomitic substrate. The overlying Asbestos Hills Subgroup banded iron formation (BIF) is suggested as a potential source of alkali metals, which also provides a mechanism for leaching of these BIFs to form high-grade residual iron ore deposits.
The Impact of Surface Functionalization on the Biophysical Properties of Silver Nanoparticles
Authors: Borowik Agnieszka , Butowska Kamila , Konkel Kinga , Banasiuk Rafał , Derewonko Natalia , Wyrzykowski Dariusz , Davydenko Mykola , Cherepanov Vsevolod , Styopkin Viktor , Prylutskyy Yuriy , Pohl Paweł , Krolicka Aleksandra , Piosik Jacek
Published: July 2019

Among metal-based nanoparticles, silver nanoparticles (AgNPs) are particularly appealing because of their stability, functionality, and documented antimicrobial properties. AgNPs also offer the possibility of different surface modifications. In this work, we functionalized AgNPs with thiobarbituric acid or 11-mercaptoundecanoic acid residues to improve the nanoparticles’ biological activities. Subsequently, we assessed the physicochemical properties of newly synthesized AgNPs using a wide range of biophysical methodologies, including UV/vis and fluorescence spectroscopy, atomic force and scanning electron microscopy, and dynamic light scattering and isothermal titration calorimetry. Next, we examined the effect of nanoparticles functionalization on AgNPs mutagenicity and toxicity. Our study revealed that AgNPs’ surface modification affects nanoparticles aggregation, and also impacts nanoparticles’ interaction with model acridine mutagen ICR-191. AgNPs coated with MUA showed the most interesting interactions with tested ICR-191, slightly modulating its toxicity properties by decreasing the viability in treated cells.
Socioeconomic Inequalities in the Retail Food Environment around Schools in a Southern European Context
Authors: Díez Julia , Cebrecos Alba , Rapela Alba , Borrell Luisa N. , Bilal Usama , Franco Manuel
Published: July 2019

Across Europe, excess body weight rates are particularly high among children and adolescents living in Southern European contexts. In Spain, current food policies appeal to voluntary self-regulation of the food industry and parents’ responsibility. However, there is no research (within Spain) assessing the food environment surrounding schools. We examined the association between neighborhood-level socioeconomic status (NSES) and the spatial access to an unhealthy food environment around schools using both counts and distance measures, across the city of Madrid. We conducted a cross-sectional study citywide (n = 2443 census tracts). In 2017, we identified all schools (n = 1321) and all food retailers offering unhealthy food and beverages surrounding them (n = 6530) using publicly available data. We examined both the counts of retailers (within 400 m) and the distance (in meters) from the schools to the closest retailer. We used multilevel regressions to model the association of neighborhood-level socioeconomic status (NSES) with both measures, adjusting both models for population density. Almost all schools (95%) were surrounded by unhealthy retailers within 400 m (median = 17 retailers; interquartile range = 8–34). After adjusting for population density, NSES remained inversely associated with unhealthy food availability. Schools located in low-NSES areas (two lowest quintiles) showed, on average, 29% (IRR (Incidence Rate Ratio) = 1.29; 95% CI (Confidence Interval) = 1.12, 1.50) and 62% (IRR = 1.62; 95% CI = 1.35, 1.95) more counts of unhealthy retailers compared with schools in middle-NSES areas (ref.). Schools in high-NSES areas were farther from unhealthy food sources than those schools located in middle-NSES areas (β = 0.35; 95% CI = 0.14, 0.47). Regulating the school food environment (within and beyond school boundaries) may be a promising direction to prevent and reduce childhood obesity.
Effects of Gelidium elegans on Weight and Fat Mass Reduction and Obesity Biomarkers in Overweight or Obese Adults: A Randomized Double-Blinded Study
Authors: Kim Choon Ok , Kim Youn Nam , Lee Duk-Chul
Published: July 2019

The edible seaweed Gelidium elegans (GEE) is known to inhibit adipocyte differentiation. However, there has been no report on its effects in humans. In this study, we investigated whether GEE reduces body weight or fat mass in obese or overweight individuals. A total of 78 participants were randomly assigned to the test (GEE extract 1000 mg/day) and placebo groups at a 1:1 ratio, and treated for 12 weeks. At six or 12 weeks after randomization, they were evaluated for anthropometric parameters, biomarkers, and body composition. Changes in body weight and fat mass between the two groups was significantly different, as determined using ANCOVA adjusted for baseline, calorie intake, and physical activity. Body weight and fat mass were significantly decreased by GEE after 12 weeks but increased in the placebo group. Moreover, although not significant, triglyceride levels tended to decrease after GEE intake. There was no significant difference in other laboratory biomarkers between the two groups. Taken together, these results suggested that GEE significantly reduced body weight, especially fat mass, in overweight or obese individuals.
Nutrition and Breast Cancer: A Literature Review on Prevention, Treatment and Recurrence
Authors: De Cicco Paola , Catani Maria Valeria , Gasperi Valeria , Sibilano Matteo , Quaglietta Maria , Savini Isabella
Published: July 2019

Breast cancer (BC) is the second most common cancer worldwide and the most commonly occurring malignancy in women. There is growing evidence that lifestyle factors, including diet, body weight and physical activity, may be associated with higher BC risk. However, the effect of dietary factors on BC recurrence and mortality is not clearly understood. Here, we provide an overview of the current evidence obtained from the PubMed databases in the last decade, assessing dietary patterns, as well as the consumption of specific food-stuffs/food-nutrients, in relation to BC incidence, recurrence and survival. Data from the published literature suggest that a healthy dietary pattern characterized by high intake of unrefined cereals, vegetables, fruit, nuts and olive oil, and a moderate/low consumption of saturated fatty acids and red meat, might improve overall survival after diagnosis of BC. BC patients undergoing chemotherapy and/or radiotherapy experience a variety of symptoms that worsen patient quality of life. Studies investigating nutritional interventions during BC treatment have shown that nutritional counselling and supplementation with some dietary constituents, such as EPA and/or DHA, might be useful in limiting drug-induced side effects, as well as in enhancing therapeutic efficacy. Therefore, nutritional intervention in BC patients may be considered an integral part of the multimodal therapeutic approach. However, further research utilizing dietary interventions in large clinical trials is required to definitively establish effective interventions in these patients, to improve long-term survival and quality of life.
Isolation and Characterization of Nanocellulose with a Novel Shape from Walnut (Juglans Regia L.) Shell Agricultural Waste
Authors: Zheng Dingyuan , Zhang Yangyang , Guo Yunfeng , Yue Jinquan
Published: July 2019

Herein, walnut shell (WS) was utilized as the raw material for the production of purified cellulose. The production technique involves multiple treatments, including alkaline treatment and bleaching. Furthermore, two nanocellulose materials were derived from WS by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) oxidation and sulfuric acid hydrolysis, demonstrating the broad applicability and value of walnuts. The micromorphologies, crystalline structures, chemical functional groups, and thermal stabilities of the nanocellulose obtained via TEMPO oxidation and sulfuric acid hydrolysis (TNC and SNC, respectively) were comprehensively characterized. The TNC exhibited an irregular block structure, whereas the SNC was rectangular in shape, with a length of 55–82 nm and a width of 49–81 nm. These observations are expected to provide insight into the potential of utilizing WSs as the raw material for preparing nanocellulose, which could address the problems of the low-valued utilization of walnuts and pollution because of unused WSs.
Charge Injection Characteristics of Semi-Conductive Composites with Carbon Black-Polymer for HVDC Cable
Authors: Wei Yanhui , Liu Mingyue , Han Wang , Li Guochang , Hao Chuncheng , Lei Qingquan
Published: July 2019

Semi-conductive composites composed of carbon black-polymer play an important role in uniform electric field in high voltage direct current (HVDC) cable. They also affect space charge behaviors in the insulation material. However, the charge injection characteristics of semi-conductive composites are not detailed. In this work, the electrode structure of ‘Semi-conductive composites- Insulation material- Metal bottom’ (S-I-M) is proposed, and the currents formed by injected charges from semi-conductive composites are characterized by the thermally stimulated depolarization current (TSDC) method. Further, the experimental results based on the structure of S-I-M are compared with the traditional electrode structure of M-I-M (Metal upper electrode- Insulation material- Metal bottom electrode) and the simplified cable electrode structure of MS-I-M (Metal upper electrode-Semi-conductive electrode- Insulation material- Metal bottom electrode), respectively. The experimental results show that the semi-conductive composite plays an important role in the charge injection process and it presents a different tendency under different compound modes of temperature and electric field. For the low electric field (E ≤ 5 kV/mm) and the low temperature (T ≤ 50 °C), the current caused by the accumulated charges follows the rule, IS > IMS > IM. For the low electric field and high temperature (T > 50 °C), the current caused by the injected charges follows the rule, IMS > IM > IS. This phenomenon is closely related to the interface characterization and contact barrier.
Investigation of the Constitutive Model of W/PMMA Composite Microcellular Foams
Authors: Zhu Yuxuan , Luo Guoqiang , Zhang Ruizhi , Liu Qiwen , Sun Yi , Zhang Jian , Shen Qiang , Zhang Lianmeng
Published: July 2019

Investigating the constitutive relationship of a material can provide better understanding of the mechanical properties of a material and has an irreplaceable effect on optimizing the performance of a material. This paper investigated a constitutive model for tungsten/polymethyl-methacrylate (W/PMMA) composite microcellular foams prepared by using melt mixing and supercritical carbon dioxide foaming. The stress-strain relationships of these foams with different W contents were measured under static compression. The elastic modulus and compressive strength values of the foams were remarkably greater than those of the pure PMMA foams: at a W content of 20 wt %, these values were increased by 269.1% and 123.9%, respectively. Based on the Maxwell constitutive model, the relevant coefficients were fitted according to the experimental data of different relative densities and W contents in quasi-static compression. According to the numerical relationships between the relevant coefficients and the relative densities and W contents, the quasi-static mechanical constitutive model of W/PMMA composite microcellular foams with W contents of 0~60 wt % and relative densities of 0.15~0.55 were predicted. This study provided basic data for the optimal design of the W/PMMA composite microcellular foams and proposed a method for investigating the mechanical properties of composite microcellular foam materials.
Curing and Characteristics of N,N,N′,N′-Tetraepoxypropyl-4,4′-Diaminodiphenylmethane Epoxy Resin-Based Buoyancy Material
Authors: Yu Sizhu , Li Xiaodong , Guo Xiaoyan , Li Zhiren , Zou Meishuai
Published: July 2019

Buoyancy material is a type of low-density and high-strength composite material which can provide sufficient buoyancy with deep submersibles. A new buoyancy material with N,N,N′,N′-tetraepoxypropyl-4,4′-diaminodiphenylmethane epoxy resin (AG-80) and m-xylylenediamine (m-XDA) curing agent as matrix and hollow glass microsphere (HGM) as the filler is prepared. The temperature and time of the curing process were determined by the calculations of thermal analysis kinetics (TAK) through differential scanning calorimetry (DSC) analysis. The results show that the better mass ratio of AG-80 with m-XDA is 100/26. Combined TAK calculations and experimental results lead to the following curing process: pre-curing at 75 °C for 2 h, curing at 90 °C for 2 h, and post-curing at 100 °C for 2 h. The bulk density, compressive strength, and saturated water absorption of AG-80 epoxy resin-based buoyancy material were 0.729 g/cm3, 108.78 MPa, and 1.23%, respectively. Moreover, this type of buoyancy material can resist the temperature of 250 °C.
Highly Selective Fluorescence Sensing and Imaging of ATP Using a Boronic Acid Groups-Bearing Polythiophene Derivate
Authors: Liu Lihua , Zhao Linlin , Cheng Dandan , Yao Xinyi , Lu Yan
Published: July 2019

A boronic acid groups-bearing polythiophene derivate (L) was designed and synthesized for highly sensitive fluorescence detection of ATP based on a multisite-binding coupled with analyte-induced aggregation strategy. L has a polythiophene backbone as fluorophores and two functional side groups, i.e., quaternary ammonium group and boronic acid group, as multibinding sites for ATP. When various structural analogues such as ADP, AMP, and various inorganic phosphates were added into the aqueous solution of L, only ATP caused a remarkable fluorescence quenching of about 60-fold accompanied by obvious color changes of solution from yellow to purple. The detection limit is estimated to be 2 nM based on 3σ/slope. With the advantage of good water solubility, low toxicity, and highly selective response to ATP, L was successfully utilized as a probe to real-time assay activity of adenylate kinase (ADK) and map fluorescent imaging of ATP in living cells.
Innovative Effluent Capture and Evacuation Device that Increases COD Removal Efficiency in Subsurface Flow Wetlands
Authors: Cisterna-Osorio Pedro , Lazcano-Castro Verónica , Silva-Vasquez Gisela , Llanos-Baeza Mauricio , Fuentes-Ortega Ignacio
Published: July 2019

The objective of this work is to evaluate the impact of innovative modifications made to conventional effluent capture and discharge devices used in subsurface flow wetlands (SSFW). The main modifications that have been developed extend the influence of the capture and discharge device in such a way that the SSFW width and height are fully covered. This improved innovative device was applied and evaluated in two subsurface flow wetlands, one on a pilot scale and one on a real scale. To evaluate the impact of the innovative device with respect to the conventional one in the operational functioning of subsurface flow wetlands, the elimination of chemical oxygen demand (COD) was measured and compared. The results show that for the innovative device, the COD removal was 10% higher than for the conventional device, confirming the validity and effectiveness of the modifications implemented in the effluent capture and discharge devices used in SSFW.
Finite Time Thermodynamic Optimization of an Irreversible Proton Exchange Membrane Fuel Cell for Vehicle Use
Authors: Li Changjie , Liu Ye , Xu Bing , Ma Zheshu
Published: July 2019

A finite time thermodynamic model of an irreversible proton exchange membrane fuel cell (PEMFC) for vehicle use was established considering the effects of polarization losses and leakage current. Effects of operating parameters, including operating temperature, operating pressure, proton exchange membrane water content, and proton exchange membrane thickness, on the optimal performance of the irreversible PEMFC are numerically studied in detail. When the operating temperature of the PEMFC increases, the optimal performances of PEMFC including output power density, output efficiency, ecological objective function, and ecological coefficient of performance, will be improved. Among them, the optimal ecological objective function increased by 81%. The proton film thickness has little effect on the output efficiency and the ecological of coefficient performance. The maximum output power density increased by 58% as the water content of the proton exchange membrane increased from 50% to the saturation point. The maximum output power density increases with the operating pressure.
Recent Novel Hybrid Pd–Fe3O4 Nanoparticles as Catalysts for Various C–C Coupling Reactions
Authors: Jang Sanha , Hira Shamim Ahmed , Annas Dicky , Song Sehwan , Yusuf Mohammad , Park Ji Chan , Park Sungkyun , Park Kang Hyun
Published: July 2019

The use of nanostructure materials as heterogeneous catalysts in the synthesis of organic compounds have been receiving more attention in the rapid developing area of nanotechnology. In this review, we mainly focused on our own work on the synthesis of hybrid palladium–iron oxide nanoparticles. We discuss the synthesis of Pd–Fe3O4—both morphology-controlled synthesis of Pd–Fe3O4 and transition metal-loaded Pd–Fe3O4—as well as its application in various C–C coupling reactions. In the case of rose-like Pd–Fe3O4 hybrid nanoparticles, thermal decomposition can be used instead of oxidants or reductants, and morphology can be easily controlled. We have developed a method for the synthesis of nanoparticles that is facile and eco-friendly. The catalyst was recyclable for up to five continual cycles without significant loss of catalytic activity and may provide a great platform as a catalyst for other organic reactions in the near future.
Open Access Routes Dichotomy and Opportunities: Consolidation, Analysis and Trends at the Spanish National Research Council
Authors: Baquero-Arribas Mercedes , Dorado Luis , Bernal Isabel
Published: July 2019

This article gives a comprehensive overview of recent Spanish National Research Council (CSIC) publications available in Open Access. With a focus on research articles from the last decade (2008–2018), this work aims to fill the gap in previous studies about publishing trends and impact monitoring of publications by researchers from the Spanish National Research Council. Evolution and main trends of Green and Gold Open Access routes at CSIC are addressed through a close insight into DIGITAL.CSIC repository and institutional Open Access Publishing Support Programme. The article draws on major conclusions at a time when an institutional Open Access mandate has just entered into force. The article also relates findings about performance of institutional Open Access Publishing Initiative and total volume of CSIC articles published in Open Access with an estimation of overall costs on article processing charges during these years. Furthermore, the data serve as a basis to make preliminary considerations as to opportunities to move from a subscription-based model to one fully aligned with Gold Open Access publishing. The data analyzed come from a variety of sources, including public information and internal records maintained by the CSIC E-resources Subscription programme, DIGITAL.CSIC and data retrieved from GesBIB, an internal, in-house development tool that integrates bibliographic information about CSIC publications as well as data from several external APIs, including Unpaywall, DOAJ and Sherpa Romeo.
Can Machine Learning-Based Portfolios Outperform Traditional Risk-Based Portfolios? The Need to Account for Covariance Misspecification
Authors: Jain Prayut , Jain Shashi
Published: July 2019

The Hierarchical risk parity (HRP) approach of portfolio allocation, introduced by Lopez de Prado (2016), applies graph theory and machine learning to build a diversified portfolio. Like the traditional risk-based allocation methods, HRP is also a function of the estimate of the covariance matrix, however, it does not require its invertibility. In this paper, we first study the impact of covariance misspecification on the performance of the different allocation methods. Next, we study under an appropriate covariance forecast model whether the machine learning based HRP outperforms the traditional risk-based portfolios. For our analysis, we use the test for superior predictive ability on out-of-sample portfolio performance, to determine whether the observed excess performance is significant or if it occurred by chance. We find that when the covariance estimates are crude, inverse volatility weighted portfolios are more robust, followed by the machine learning-based portfolios. Minimum variance and maximum diversification are most sensitive to covariance misspecification. HRP follows the middle ground; it is less sensitive to covariance misspecification when compared with minimum variance or maximum diversification portfolio, while it is not as robust as the inverse volatility weighed portfolio. We also study the impact of the different rebalancing horizon and how the portfolios compare against a market-capitalization weighted portfolio.
Sentinel-3A SRAL Global Statistical Assessment and Cross-Calibration with Jason-3
Authors: Yang Jungang , Zhang Jie , Wang Changying
Published: July 2019

The Sentinel-3A satellite, equipped with Synthetic Aperture Radar (SAR) Altimeter (SRAL) instrument to derive sea surface height, significant wave height and surface wind speed over the global ocean, was launched on 16 February 2016. The assessment of data quality and the system performance of the altimeter are very important to data application. In this article, Sentinel-3A SRAL data quality is assessed and altimetry system performance is estimated by verifying data availability and monitoring the parameters of altimeter and radiometer through the global statistical analyses of Sentinel-3A Non-Time-Critical (NTC) Marine Level 2 products during the period from 13 March 2016 to 25 February 2019, in comparison with self-crossovers and cross-calibration with the Jason-3 mission. The global statistical analyses and the comparisons at self-crossovers show that Sentinel-3A SRAL data and performance are stable and have no trend over time, and the total cycle average root mean square errors (RMSEs) of sea surface height (SSH) differences at self-crossovers is about 5.4 cm. The comparisons at the dual-crossovers show the consistency of the observation between Sentinel-3A SRAL and Jason-3, and indicate that the systemic bias of SSH is about 2.96 cm. In general, it can be concluded that Sentinel-3A SRAL has good and stable data quality and system performance for operational ocean forecasting and scientific research.
Estimating Live Fuel Moisture Using SMAP L-Band Radiometer Soil Moisture for Southern California, USA
Authors: Jia Shenyue , Kim Seung Hee , Nghiem Son V. , Kafatos Menas
Published: July 2019

Live fuel moisture (LFM) is a field-measured indicator of vegetation water content and a crucial observation of vegetation flammability. This study presents a new multi-variant regression model to estimate LFM in the Mediterranean ecosystem of Southern California, USA, using the Soil Moisture Active Passive (SMAP) L-band radiometer soil moisture (SMAP SM) from April 2015 to December 2018 over 12 chamise (Adenostoma fasciculatum) LFM sites. The two-month lag between SMAP SM and LFM was utilized either as steps to synchronize the SMAP SM to the LFM series or as the leading time window to calculate the accumulative SMAP SM. Cumulative growing degree days (CGDDs) were also employed to address the impact from heat. Models were constructed separately for the green-up and brown-down periods. An inverse exponential weight function was applied in the calculation of accumulative SMAP SM to address the different contribution to the LFM between the earlier and present SMAP SM. The model using the weighted accumulative SMAP SM and CGDDs yielded the best results and outperformed the reference model using the Moderate Resolution Imaging Spectroradiometer (MODIS) Visible Atmospherically Resistance Index. Our study provides a new way to empirically estimate the LFM in chaparral areas and extends the application of SMAP SM in the study of wildfire risk.
Latent Heat Flux in the Agulhas Current
Authors: Imbol Nkwinkwa N. Arielle Stela , Rouault Mathieu , Johannessen Johnny A.
Published: July 2019

In-situ observation, climate reanalyses, and satellite remote sensing are used to study the annual cycle of turbulent latent heat flux (LHF) in the Agulhas Current system. We assess if the datasets do represent the intense exchange of moisture that occurs above the Agulhas Current and the Retroflection region, especially the new reanalyses as the former, the National Centers for Environmental Prediction Reanalysis 2 (NCEP2) and the European Centre for Medium-Range Weather Forecast (ECMWF) reanalysis second-generation reanalysis (ERA-40) have lower sea and less distinct surface temperature (SST) in the Agulhas Current system due to their low spatial resolution thus do not adequately represent the Agulhas Current LHF. We use monthly fields of LHF, SST, surface wind speed, saturated specific humidity at the sea surface (Qss), and specific humidity at 10 m (Qa). The Climate Forecast System Reanalysis (CFSR), the European Centre for Medium-Range Weather Forecast fifth generation (ERA-5), and the Modern-Era Retrospective analysis for Research and Applications version-2 (MERRA-2) are similar to the air–sea turbulent fluxes (SEAFLUX) and do represent the signature of the Agulhas Current. ERA-Interim underestimates the LHF due to lower surface wind speeds than other datasets. The observation-based National Oceanography Center Southampton (NOCS) dataset is different from all other datasets. The highest LHF of 250 W/m2 is found in the Retroflection in winter. The lowest LHF (~100 W/m2) is off Port Elizabeth in summer. East of the Agulhas Current, Qss-Qa is the main driver of the amplitude of the annual cycle of LHF, while it is the wind speed in the Retroflection and both Qss-Qa and wind speed in between. The difference in LHF between product are due to differences in Qss-Qa wind speed and resolution of datasets.