Increment In Magnitude Research Articles

Scrutiny of pseudoplastic nanofluid flow under the influence of magnetic hydrodynamics with chemical reaction across the cylinder with slip boundary condition

Buoyantly induced flows possess diversified utilizations in numerous engineering processes for instance, reactor cooling through passive strategy, LED lights, pipes manufacturing, ship funnel and many more. Galvanized sheets sticked to form a hollow cylinder is used for fast cooling in naval ship and chimney of steam power plant. In view of such mesmerizing significance of flow and thermal attributes of fluid over vertical cylinder, current effort is articulated. For this purpose, Williamson fluid model is accounted and nanoparticles are also induced to envision advanced thermal features in the flow over vertically oriented cylinder. Physical effectiveness of magnetic field implications and chemical reactive species are entertained to notice change in hydrothermal and mass fields. Slip boundary constraint along with stagnant flow at the surface of cylinder is considered to inspect behavior in free stream region. The fundamental governing equations of problem are attained in the sense of PDEs by utilizing the concept of boundary layer approximation and converted into coupled nonlinear ODEs by substituting specific similar variables. Numerically the resulting ODEs are resolved by making the use of bvp4c built in MATLAB routine, the outcomes are attained and arranged in graphical and tabular manner. The influence of pertinent flow parameters such as (0.1 ≤ We ≤ 1.0), (1.0 ≤ M ≤ 3.0), (1.0 ≤ Pr ≤ 11), thermophoresis parameter (0.5 ≤ Tp ≤ 4.5), (1.0 ≤ Bp ≤ 5.0), (0.05 ≤ Nr ≤ 0.7), and (0.5 ≤ Kc ≤ 5.0) are examined on the momentum, thermal and concentration distributions. It is manifested that the velocity distribution depreciates by uplifting magnetic field strength. Increment in magnitude of wall drag and convective heat transfer is perceived by enhancing Prandtl number. It is inferred that friction coefficient in absolute sense and heat flux coefficient tends to exceed against elevation in (We). From comprehensive analysis, declination in velocity and thermal field is depicted versus Reynold number whereas, contrary aspects are visualized in concentration. Enhancement in the value of surface drag and thermal flux is revealed versus (Re).

Entropy-Based Multifractal Testing of Heart Rate Variability during Cognitive-Autonomic Interplay.

Entropy-based and fractal-based metrics derived from heart rate variability (HRV) have enriched the way cardiovascular dynamics can be described in terms of complexity. The most commonly used multifractal testing, a method using q moments to explore a range of fractal scaling in small-sized and large-sized fluctuations, is based on detrended fluctuation analysis, which examines the power-law relationship of standard deviation with the timescale in the measured signal. A more direct testing of a multifractal structure exists based on the Shannon entropy of bin (signal subparts) proportion. This work aims to reanalyze HRV during cognitive tasks to obtain new markers of HRV complexity provided by entropy-based multifractal spectra using the method proposed by Chhabra and Jensen in 1989. Inter-beat interval durations (RR) time series were obtained in 28 students comparatively in baseline (viewing a video) and during three cognitive tasks: Stroop color and word task, stop-signal, and go/no-go. The new HRV estimators were extracted from the f/α singularity spectrum of the RR magnitude increment series, established from q-weighted stable (log-log linear) power laws, namely: (i) the whole spectrum width (MF) calculated as αmax - αmin; the specific width representing large-sized fluctuations (MFlarge) calculated as α0 - αq+; and small-sized fluctuations (MFsmall) calculated as αq- - α0. As the main results, cardiovascular dynamics during Stroop had a specific MF signature while MFlarge was rather specific to go/no-go. The way these new HRV markers could represent different aspects of a complete picture of the cognitive-autonomic interplay is discussed, based on previously used entropy- and fractal-based markers, and the introduction of distribution entropy (DistEn), as a marker recently associated specifically with complexity in the cardiovascular control.

Mechanical behavior of high-pressure pipeline installed through horizontal directional drilling under seismic loads

The present study investigates the mechanical behavior of high-pressure pipelines installed through horizontal directional drilling (HDD), a crucial trenchless installation method, under seismic loads. Utilizing the finite element method and artificial viscoelastic boundary conditions, this paper analyzes the stress response of pipelines subjected to seismic loads in two directions. The seismic loads are applied using the response spectrum method, and the pipeline stress is analyzed in time history. A comparison of the stress in pipelines installed through the HDD method and the traditional open-cut method is conducted, and the impact of earthquake magnitude on pipeline stress is evaluated. The results indicate that the pipeline stress is greater when the seismic acceleration acts transversely, with bending deformation being the dominant mode of response. A 9.29% increase in maximum stress is observed for each increment in earthquake magnitude. Furthermore, the stress in pipelines installed through the HDD method is 48% lower than that of pipelines installed using the open-cut method when subjected to transverse seismic loads.

Investigation of third-order nonlinear optical properties in two novel ethyne-linked chromophores: Effect of donor-acceptor alternation

Two novel compounds of the alternating donor (D)/acceptor (A) system were designed and synthesized. In BSB (A-π-D-π-A) and SBS (D-π-A-π-D), thiophene, 2,1,3-benzothiadiazole (BTD) and ethylene act as donor, acceptor groups and π-bridge moiety, respectively. Z-scan experiments at 532 nm with various pulse durations show a transition from saturable absorption to reverse saturable absorption and self-defocusing effects in both compounds. The different alternating modes of D-A units lead to an order of magnitude increment in the second-order hyperpolarizability γ of SBS (4.4 × 10−28 esu) compared to BSB. Ultrafast transient absorption spectroscopy was carried out to analyze the enhancement of second-order hyperpolarizability. Results indicate that this enhancement originates from excited state absorption of the long-lived intramolecular charge transfer state. Using quantum chemical calculations, the stronger symmetrical intramolecular charge transfer in SBS can be demonstrated by the difference between the ground- and excited-state dipole moments Δμge. It is shown intuitively in the S0–S1 hole-electron analysis. All of the experimental and theoretical results suggest that changing the D-A alternation in organic molecules can effectively modulate the third-order nonlinear optical behavior, which may serve as a guide for future molecular design.

Fluorine-free and ultra-thin films prepared by RF-PECVD method for the anticorrosive applications

The high-reliability requirement of 5 G electronic products poses a higher challenge to its protective films, the high transmission quality of high-frequency signals, excellent heat dissipation and anticorrosive capability, which promotes the ultra-thin protective films with good adhesion and anticorrosion. In this work, a nanometer-scale p-HMDSO film was obtained on the Cu alloy with hexamethyldisiloxane (HMDSO) as the precursor by the low-temperature RF-PECVD method. Compared with Parylene and p-PFDA (1H, 1H, 2H, 2H-Perfluorodecyl acrylate) films, the p-HMDSO film possesses better hydrophobicity, mechanical stability and anticorrosive property. The corrosion inhibition efficiency of the p-HMDSO film reaches 99.95%. Meanwhile, it provides 3 orders of magnitude increment of charge-transfer impedance, a salt spray corrosion resistance for 24 h, and the protection of 10 days in the 3.5 wt% NaCl solution, which develops a better application prospect in the protection of integrated electronics.

Characterizing Current THD’s Dependency on Solar Irradiance and Supraharmonics Profiling for a Grid-Tied Photovoltaic Power Plant

The rapidly increasing distributed energy resources (DERs) in power systems are now getting interconnected to set community grid structures, where power quality will be a major concern. The grid-to-grid (G2G) bidirectional power transfer among the distribution microgrid will not be considered commercially feasible unless the upstream harmonics are under the limits. The aggregation of such harmonics, measured as total harmonic distortion (THD), is feared to be beyond tolerable limits with the progression of rooftop grid-tied PV-like installations. Hence, this THD needs to be characterized with DER generation end variables. In this work, the photovoltaic (PV) DERs’ dependency on environment variables such as irradiance was profiled in the context of generating and injecting harmonics into the grid. A mathematical model of a grid-tied three-phase PV DER was developed as part of this correlation characterization, matching the fundamental unit structure of a 1.4 MW solar canopy located on the Florida International University (FIU) Miami campus. To determine the qualitative association with produced THD patterns, the model was evaluated with various irradiance settings. A real-time digital simulation (RTDS) platform was used to verify it. Following this confirmation, sets of data from power quality meters at the point of common coupling and FIU field sensors were utilized to validate further the correlation model. The results showed that the grid current’s THD exhibited a high correlation with the irradiance profile and its variation over time. The early morning and late afternoon periods of the day, associated with a low irradiance, constantly had higher harmonics generated from the PV DER. The midday THD was rather rational with partial shadings, hence a geolocation-dependent factor. These findings were verified by an RTDS and validated by real field data. In quantifying the THD injected by a single DER at a high-frequency (2–150 kHz) supraharmonics (SH) level, a 3% peak increment in magnitude was observed from the high-fixed to the low-fixed irradiance profile. The correlation characteristics depicted that the hybrid microgrid suffered from a daytime-dependent harmonic insertion from the grid-tied DER. This is a global problem unless specific measures are taken to mitigate the harmonics. The electrically notorious higher-frequency SH was found to increase proportionally. The G2G power transfer can be limited because of the higher THD in the early morning and late afternoon, which will also worsen because the numbers of grid-tied PV DERs (i.e., rooftop solar and industrial solar) are likely to increase rapidly soon. The community grid structure can thus have a controlled harmonics filtration setup purposefully designed to address the findings of this work, which also fall within the scope of our future research.

Pressure-Tuning Photothermal Synergy to Optimize the Photoelectronic Properties in Amorphous Halide Perovskite Cs3 Bi2 I9.

Effective modification of the structure and properties of halide perovskites via the pressure engineering strategy has attracted enormous interest in the past decade. However, sufficient effort and insights regarding the potential properties and applications of the high-pressure amorphous phase are still lacking. Here, the superior and tunable photoelectric properties that occur in the pressure-induced amorphization process of the halide perovskite Cs3 Bi2 I9 are demonstrated. With increasing pressure, the photocurrent with xenon lamp illumination exhibits a rapid increase and achieves an almost five orders of magnitude increment compared to its initial value. Impressively, a broadband photoresponse from 520 to 1650nm with an optimal responsivity of 6.81mA W-1 and fast response times of 95/96ms at 1650nm is achieved upon successive compression. The high-gain, fast, broadband, and dramatically enhanced photoresponse properties of Cs3 Bi2 I9 are the result of comprehensive photoconductive and photothermoelectric mechanisms, which are associated with enhanced orbital coupling caused by an increase in BiI interactions in the [BiI6 ]3- cluster, even in the amorphous state. These findings provide new insights for further exploring the potential properties and applications of amorphous perovskites.

Metal-Air Field Emission Devices - Nano Electrode Geometries Comparison of Performance and Stability.

Air-channel devices have a special advantage due to the promise of vacuum-like ballistic transport in air, radiation insensitivity, and nanoscale size. Here, achieving high current at low voltage along with considerable mechanical stability is a primary issue. The comparative analysis of fourplanar and metallic electrode-pair geometries at 10nm channel length is presented. The impact of nano-electrode-pair geometries on overall device performance is investigated. Air-channel devices are operated at the ultra-low voltage of 5mV to demonstrate the device dynamics of air-channel devices at low power. Investigations focus on the direct tunneling (DT) mechanism which is dominant in thelow-voltage regime. Comparative analysis of different electrode-pair geometries revealstwo orders of magnitude increment in the current just by modulating the electrode-pair structure. Theoretical analysis suggests that the emission current is directly related to the active junction area within the metal-air-metal interface at the direct tunneling regime. The geometry-dependent mechanical stability of different electrode pairs is compared by imaging biasing triggered nanoscale structural changes and pulsed biasing stress analysis. The results and claims are confirmed and consolidated with the statistical analysis. Experimental investigations provide strong directions for high-performance and stable devices. In-depth theoretical discussions will enable the accurate modeling of emerging low-power, high-speed, radiation-hardened nanoscale vacuum electronics.

Improved electromagnetic interference shielding properties of poly (vinylidene fluoride) composites based on carbon nanotubes and graphene nanoplatelets

AbstractIn order to improve the electromagnetic interference (EMI) shielding performance of poly(vinylidene fluoride) (PVDF), both carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) as functional fillers were chosen and employed in this work. The PVDF‐based composites were prepared through melt blending and the hybrid fillers exhibited fine interaction with PVDF matrix. CNTs and GNPs could act as heterogeneous nucleation agents for PVDF matrix, thus increased the crystallization peak temperature. The gradual formation of interconnected conductive network of hybrid fillers could improve the conductivity and rheological properties of PVDF effectively. Especially, in contrast to those of pure PVDF, about four orders of magnitude increment for their storage modulus and complex viscosity of PVDF/GNPs/CNTs composite as well as approximate 10 orders of magnitude improvement in their electrical conductivity were obtained. Adding 2 wt% CNTs in PVDF matrix could generate the conductive network and further GNPs addition was helpful to obtain higher EMI shielding effectiveness. The new PVDF samples would possess wide applications as electromagnetic shielding materials, on account of their simple processing, low‐cost and without use of organic solvent characteristics.

Electromagnetic shielding performance of acrylonitrile-butadiene-styrene/CNTs composite foams with different cell structures

In this work, three representative cell structures (nano-, micro- and regular cells) were designed and tailored in acrylonitrile-butadiene-styrene (ABS) composite foams by altering carbon nanotubes (CNTs) content and adjusting foaming temperature in the presence of supercritical CO2. Compared with pure ABS, nearly 2 orders of magnitude increment in the storage modulus and complex viscosity of ABS/CNTs composites and about 9 orders of magnitude improvement in their electrical conductivity were obtained. Compared with its unfoamed sample, the electromagnetic interference specific shielding effectiveness (SSE) of ABS/CNTs7 foam prepared at 145 °C was enhanced from 22.75 to 26.60 dB cm3/g. A specific interface area model was established to discuss the electromagnetic absorption of ABS/CNTs foams with different cell structures. The results demonstrated that the larger the cell size, the higher the specific interface area of different ABS foams with same CNTs content, as a result, higher SSE was achieved.

Multisalt chemistry in ion transport and interface of lithium metal polymer batteries

Solvent-free solid-state polymer electrolytes (SPE) that go beyond the barriers like intrinsic low ionic conductivity, slow ion dynamics, and unstable electrode-electrolyte interphase will be fundamental for realizing the next generation of safe and high-performance lithium metal batteries. Hereby, cross-linked solid polymer electrolyte (XSPE) networks based on multisalt chemistry are synthesized using photopolymerization reaction, which outshine the conventional single salt-based XSPEs. By introducing the multisalt chemistry, an enhanced Li+ ion transport (ionic conductivity and short residence time) via anion mediated transfer (AMT) and improved interfacial characteristics (e.g., stable Li|electrolyte interphase, smooth Li-deposition) are demonstrated. Furthermore, a three-times increase in Li+ ion transference number and nearly one order of magnitude increment in diffusion coefficient are achieved. Using theoretical calculations, we propose an AMT-based ion conduction pathway in multisalt-based XSPEs. Besides, the superior electrochemical performance of multisalt-based XSPEs compared to single salt-based polymer electrolytes in Li-metal polymer batteries (LMPB) using C-LiFePO4 and LiNi0.8Co0.15Al0.05O2 cathodes are successfully demonstrated.

Interpenetrating Lattices with Tailorable Energy Absorption in Tension

This paper introduces the chain lattice, a hierarchical porous structure comprising two interpenetrating cellular solids. One constituent toughens the material and prevents catastrophic localized failure while the other serves as a porous matrix which densifies to absorb energy during tensile loading. Through tension testing, we demonstrate 3D-printed plastic chain lattices that exhibit delocalized damage and an order of magnitude increment in strain-to-failure over the fully dense base material. These experiments validate a micromechanics-based model of tensile specific energy absorption, which we then use in a parametric study on the effects of chain geometry and matrix properties on tensile behavior. We find that ceramic chain lattices can achieve an order of magnitude improvement in tensile specific energy absorption over the fully dense material, in line with the improvement seen when forming monolithic ceramics into fiber-reinforced ceramic matrix composites. The experiments and analysis highlight the ability of the chain lattice to impart damage-tolerance to 3D-printable materials that are normally brittle and flaw-sensitive.

Content and morphology of lead remediated by activated carbon and biochar: A spectral induced polarization study

Soil and groundwater contamination with lead (Pb) poses serious challenges for the environment. Activated carbon (AC) and biochar have huge potential application in the in-situ remediation processes through permeable reactive barriers (PRB). Spectral induced polarization (SIP) technique recently showed promises in nondestructively monitoring the spatio-temporal characteristics of physical, chemical and biological processes in porous media. In this study SIP technique was used for monitoring Pb remediation by AC and biochar in column scale. The calculated characteristic grain/pore size evolutions from SIP signals on AC, agreed well with the size of precipitates measured by SEM and mercury intrusion porosimetry (MIP) methods. The content increment process of the retained Pb on AC was also recorded via the magnitude increment of the imaginary conductivity. The mechanisms of Pb–AC and Pb-biochar interactions were investigated using SEM-EDS, TEM, FTIR, XRD, and XPS measurements. It showed that AC immobilizes through physical adsorption and precipitation, whereas complexation with functional groups is the remediation mechanism for biochar. Furthermore, the observed SIP responses of both AC and biochar are two orders of magnitude higher than those of typical natural soils or silica materials. This distinct difference is an additional advantage for the field application of SIP technique in PRB scenarios.

Prosthetic aortic graft replacement of the ascending thoracic aorta alters biomechanics of the native descending aorta as assessed by transthoracic echocardiography.

IntroductionIn patients with ascending aortic (AA) aneurysms, prosthetic graft replacement yields benefit but risk for complications in the descending aorta persists. Longitudinal impact of AA grafts on native descending aortic physiology is poorly understood.MethodsTransthoracic echocardiograms (echo) in patients undergoing AA elective surgical grafting were analyzed: Descending aortic deformation indices included global circumferential strain (GCS), time to peak (TTP) strain, and fractional area change (FAC). Computed tomography (CT) was used to assess aortic wall thickness and calcification.Results46 patients undergoing AA grafting were studied; 65% had congenital or genetically-associated AA (30% bicuspid valve, 22% Marfan, 13% other): After grafting (6.4±7.5 months), native descending aortic distension increased, irrespective of whether assessed based on circumferential strain or area-based methods (both p<0.001). Increased distensibility paralleled altered kinetics, as evidenced by decreased time to peak strain (p = 0.01) and increased velocity (p = 0.002). Augmented distensibility and flow velocity occurred despite similar pre- and post-graft blood pressure and medications (all p = NS), and was independent of pre-surgical aortic regurgitation or change in left ventricular stroke volume (both p = NS). Magnitude of change in GCS and FAC was 5–10 fold greater among patients with congenital or genetically associated AA vs. degenerative AA (p<0.001), paralleling larger descending aortic size, greater wall thickness, and higher prevalence of calcific atherosclerotic plaque in the degenerative group (all p<0.05). In multivariate analysis, congenital/genetically associated AA etiology conferred a 4-fold increment in magnitude of augmented native descending aortic strain after proximal grafting (B = 4.19 [CI 1.6, 6.8]; p = 0.002) independent of age and descending aortic size.ConclusionsProsthetic graft replacement of the ascending aorta increases magnitude and rapidity of distal aortic distension. Graft effects are greatest with congenital or genetically associated AA, providing a potential mechanism for increased energy transmission to the native descending aorta and adverse post-surgical aortic remodeling.

Influence of non-hydrodynamic forces on the elastic response of an ultra-thin soft coating under fluid-mediated dynamic loading

The force between two approaching solids in a liquid medium becomes increasingly large with decreasing separation—a phenomenon that prevents contact between the two solids. This growth in force occurs because of the intervening liquid, and studies of such physical systems constitute the classical discipline of lubrication. Furthermore, when the solid(s) are soft, there are quantitative as well as qualitative alterations in the force interaction due to the solids’ deformation. The underlying physics as well as resultant system behavior is even more complex when forces of non-hydrodynamic origin come into play. Two major classes of such forces are the DLVO (Derjaguin–Landau–Verwey–Overbeek) forces and the non-DLVO molecular forces. Studies assessing the coupling of these physical phenomenon are avenues of contemporary research. With this view, we perform an analytical study of oscillatory motion of a rigid sphere over an ultra-thin soft coating with an electrolytic solution filling the gap between them. We delineate the distinctive effects of solvation force as well as substrate compliance. Our key finding is the major augmentation in the force and substrate-deformation characteristics of the system due to solvation force when the confinement reduces to a few nanometers. Consideration of solvation force leads to up to four orders of magnitude and up to three orders of magnitude increment in force and substrate-deformation, respectively. While higher softness leads to higher deformation (as expected), its effect on force and substrate-deformation characteristics exhibits a tendency toward amelioration of the increment due to solvation force.

Taming the Unknown Unknowns in Complex Systems: Challenges and Opportunities for Modeling, Analysis and Control of Complex (Biological) Collectives.

Despite significant effort on understanding complex biological systems, we lack a unified theory for modeling, inference, analysis, and efficient control of their dynamics in uncertain environments. These problems are made even more challenging when considering that only limited and noisy information is accessible for modeling, which can prove insufficient for explaining, and predicting the behavior of complex systems. For instance, missing information hampers the capabilities of analytical tools to uncover the true degrees of freedom and infer the model structure and parameters of complex biological systems. Toward this end, in this paper, we discuss several important mathematical challenges that could open new theoretical avenues in studying complex systems: (1) By understanding the universal laws characterizing the asymmetric statistics of magnitude increments and the complex space-time interdependency within one process and across many processes, we can develop a class of compact yet accurate mathematical models capable to potentially providing higher degree of predictability, and more efficient control strategies. (2) In order to better predict the onset of disease and their root cause, as well as potentially discover more efficient quality-of-life (QoL)-control strategies, we need to develop mathematical strategies that not only are capable to discover causal interactions and their corresponding mathematical expressions for space and time operators acting on biological processes, but also mathematical and algorithmic techniques to identify the number of unknown unknowns (UUs) and their interdependency with the observed variables. (3) Lastly, to improve the QoL of control strategies when facing intra- and inter-patient variability, the focus should not only be on specific values and ranges for biological processes, but also on optimizing/controlling knob variables that enforce a specific spatiotemporal multifractal behavior that corresponds to an initial healthy (patient specific) behavior. All in all, the modeling, analysis and control of complex biological collective systems requires a deeper understanding of the multifractal properties of high dimensional heterogeneous and noisy data streams and new algorithmic tools that exploit geometric, statistical physics, and information theoretic concepts to deal with these data challenges.

Seismogenic nodes as a viable alternative to seismogenic zones and observed seismicity for the definition of seismic hazard at regional scale

A fixed increment of magnitude is equivalent to multiply the seismic moment by a factor γEM related to the partial factor γq acting on the seismic moment representing the fault. A comparison is made between the hazard maps obtained with the Neo-Deterministic Seismic Hazard Assessment (NDSHA), using two different approaches: one based on the events magnitude, listed in parametric earthquake catalogues compiled for the study areas, with sources located within the seismogenic zones; the other uses the seismogenic nodes identified by means of pattern recognition techniques applied to morphostructural zonation (MSZ), and increases the reference magnitude by a constant amount tuned by the safety factor γEM.Using γEM=2.0, in most of the territory the two approaches produce totally independent, comparable hazard maps, based on the quite long Italian catalogue. This represents a validation of the seismogenic nodes method and a tuning of the safety factor γEM at about 2.

Capacitance study of a polystyrene nanoparticle capacitor using impedance spectroscopy

In this study, a metal-insulator-metal capacitor structure is fabricated using polystyrene nanoparticles. Impedance spectroscopy is used to evaluate the performance of this capacitor in which we found a significant magnitude increment in capacitance and loss tangent compared with an equivalent ideal capacitor with continuous polystyrene layer and same geometry. Capacitance values up to 11.7 and loss tangent values up to 387 (at 0.1 Hz) larger than the expected for a continuous polystyrene MIM capacitor are achieved. The capacitor shows a good stable capacitive behaviour in the frequency range from 0.1 Hz to 100 kHz at room temperature, 30 °C, 40 °C and 50 °C without an effective relaxation process. Nyquist, capacitance, loss tangent and normalized powers curves are analysed by modified Randles model. Also, a slight decrease in the capacitance value at 50 °C is observed, which that may be attributed to space charge localized at the nanoparticles interface and that are affected by the temperature changes.

Generic melt compounding strategy using reactive graphene towards high performance polyethylene/graphene nanocomposites

A reactive melt compounding technique using vinyl-grafted graphene was exploited for mass production of PE/graphene nanocomposites. The as-extruded nanocomposites had good filler dispersion and interfacial interaction, as evidenced by transmission electron microscopy and linear rheological results. Compared to neat PE, the nanocomposites with 1.0 wt% graphene showed one order of magnitude and nearly two orders of magnitude increment in complex viscosity and storage modulus at low frequency (<0.1 Hz), respectively. Due to strong interfacial interaction, the graphene nanoplatelets act as nucleating agents to increase the crystallization temperature of PE, but hinder the following growth of crystallites. As a result, mechanical properties and barrier to oxygen of the nanocomposites were obviously improved. This work provides a facile strategy for mass production of high-performance polyolefin/graphene nanocomposites and may be other polymer/graphene nanocomposites.

Galactic foreground of gamma-ray bursts from AKARI Far-Infrared Surveyor

Abstract We demonstrate the use of the AKARI FIS All-Sky Survey maps in the study of extragalactic objects. A quick but reliable estimate of the Galactic foreground is essential for extragalactic research in general. We explored the galactic foreground and calculated hydrogen column densities using AKARI FIS and other recent all-sky survey data, and compared our results to former estimates. Our AKARI-FIS-based foreground values were then used toward gamma-ray burst (GRB) sources as input for X-ray afterglow spectrum fitting. From those fits the intrinsic column densities at the GRB sources were derived. The high-angular-resolution AKARI-FIS-based Galactic foreground hydrogen column densities are statistically very similar, but for most of the tested directions somewhat lower than previous estimates based on low-resolution data. This is due to the low filling factor of high-density enhancements in all galactic latitudes. Accordingly, our AKARI-FIS-based new intrinsic hydrogen column densities are usually higher or similar compared to the values calculated based, e.g., on the low-resolution Leiden/Argentine/Bonn survey data and listed in the Leicester database. The variation, however, is typically smaller than the error of the estimate from the fits of the X-ray afterglow spectra. There are a number of directions where the improvement of the foreground estimates resulted in an overestimate of magnitude or higher increment of the derived intrinsic hydrogen column densities. We concluded that most of the GRBs with formerly extremely low intrinsic hydrogen column densities are in fact normal, but we confirmed that GRB050233 is indeed a non-enveloped long GRB.