Herein, we report the effects of graphene oxides on human fibroblast cells and mice with the aim of investigating graphene oxides' biocompatibility. The graphene oxides were prepared by the modified ...Hummers method and characterized by high-resolution transmission electron microscope and atomic force microscopy. The human fibroblast cells were cultured with different doses of graphene oxides for day 1 to day 5. Thirty mice divided into three test groups (low, middle, high dose) and one control group were injected with 0.1, 0.25, and 0.4 mg graphene oxides, respectively, and were raised for 1 day, 7 days, and 30 days, respectively. Results showed that the water-soluble graphene oxides were successfully prepared; graphene oxides with dose less than 20 μg/mL did not exhibit toxicity to human fibroblast cells, and the dose of more than 50 μg/mL exhibits obvious cytotoxicity such as decreasing cell adhesion, inducing cell apoptosis, entering into lysosomes, mitochondrion, endoplasm, and cell nucleus. Graphene oxides under low dose (0.1 mg) and middle dose (0.25 mg) did not exhibit obvious toxicity to mice and under high dose (0.4 mg) exhibited chronic toxicity, such as 4/9 mice death and lung granuloma formation, mainly located in lung, liver, spleen, and kidney, almost could not be cleaned by kidney. In conclusion, graphene oxides exhibit dose-dependent toxicity to cells and animals, such as inducing cell apoptosis and lung granuloma formation, and cannot be cleaned by kidney. When graphene oxides are explored for in vivo applications in animal or human body, its biocompatibility must be considered.
Thermal conductivity is an important transport property governing the performance of polymers in non-isothermal conditions. Nevertheless, its dependence on molecular weight M has not been the subject ...of as much attention as other properties of polymeric materials. We determine the thermal conductivity of polystyrene and polyisobutylene for a wide range of molecular weight by measuring the density, heat capacity and thermal diffusivity. Using coarse-graining and reverse mapping methods, we were able to produce molecular melts to study the thermal conductivity of polystyrene using molecular dynamics simulations over a similar range of molecular weight. We find satisfactory agreement between the experimental and simulation results. However, all of our results show that thermal conductivity depends only slightly on molecular weight up the entanglement limit and it is independent thereafter. Our results put into question the few previous experimental studies on this topic by showing that the previously accepted proportionality to M does not hold. Our findings could have significant implications for the understanding of complex phenomena such as anisotropic thermal conductivity in polymers subjected to flow.
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•The thermal conductivity of two amorphous polymers having a wide range of molecular weights has been measured.•Measurements on polystyrene and polyisobutylene were made using a novel optical method and DSC and densiometry methods.•Molecular dynamics simulations methods were used to compute the thermal conductivity of polystyrene systems.•Measurements and simulations show thermal conductivity is essentially independent of molecular weight.
System response of liquefiable deposits Cubrinovski, Misko; Rhodes, Aimee; Ntritsos, Nikolaos ...
Soil dynamics and earthquake engineering,
September 2019, 2019-09-00, 20190901, Letnik:
124
Journal Article
Recenzirano
Odprti dostop
Detailed geotechnical characterization and in-depth liquefaction assessment using seismic effective stress analyses are presented for 55 liquefaction case histories (sites) from Christchurch. Fifteen ...of the sites manifested liquefaction in the two major earthquakes during the 2010–2011 Canterbury earthquakes (YY-sites), while 17 sites did not manifest liquefaction in either event (NN-sites). The YY- and NN-sites are shown to have practically identical critical layer characteristics, with low CPT tip resistance (qc1Ncs = 80–86), and shallow location of the critica.l layer at approximately 2 m depth. However, there are significant differences between the YY- and NN-sites with regard to their deposit characteristics including the thickness and vertical continuity of their critical zones and liquefiable materials.
Effective stress analyses are used to demonstrate key mechanisms of system-response of liquefying deposits that either intensify (for the YY-sites) or mitigate (for the NN-sites) liquefaction manifestation at the ground surface. The study illustrates the need to consider system-response of liquefying soils in the assessment of liquefaction manifestation and severity of liquefaction-induced damage.
•System response effects of liquefiable deposits have governing influence on liquefaction manifestation at the ground surface.•System response effects increase the severity and consequences of liquefaction manifestation for YY-sites.•A set of cascading mechanisms produce system response effects that mitigate liquefaction manifestation for NN-sites.•Simplified liquefaction evaluation procedures ignore system response of liquefiable deposits.
The problem of transcription signs used in dialect studies has been discussed in our country for many years. In 1999, Turkish Language Institute created a transcription system to solve this problem. ...Many studies on dialects have been prepared since then, but this system has not been fully followed. In this study we prepared, the transcription signs (vowels) in 56 dialects study between 1999-2019 were compared with the transcription marks in the system created by the Turkish Language Institute. In the introduction part, in these studies, why the system in question is not complied with, the studies for the solution of this problem and some studies that draw attention to this problem are mentioned. Then, the transcription signs for vowels in the system created by the Turkish Language Institution and the vowels' signs in the current studies were compared by means of some graphics and charts. In addition, this section also includes other vowel signs that are not included in the system in question, but are used in current studies. Information about the number of signs detected in the conclusion section, whether these signs are in the "Turkish Language Institution Transcription System" is given. In addition, some conclusions have been made in this section about which signs researchers have/ haven't difficulty in determining, why some signs are used more / less.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
We inverted the 2010 Maule earthquake tsunami waveforms recorded at DART (Deep‐ocean Assessment and Reporting Tsunamis) stations in the Pacific Ocean by taking into account the effects of the ...seawater compressibility, elasticity of the solid Earth, and gravitational potential change. These effects slow down the tsunami speed and consequently move the slip offshore or updip direction, consistent with the slip distribution obtained by a joint inversion of DART, tide gauge, GPS, and coastal geodetic data. Separate inversions of only near‐field DART data and only far‐field DART data produce similar slip distributions. The former demonstrates that accurate tsunami arrival times and waveforms of trans‐Pacific tsunamis can be forecast in real time. The latter indicates that if the tsunami source area is as large as the 2010 Maule earthquake, the tsunami source can be accurately estimated from the far‐field deep‐ocean tsunami records without near‐field data.
Key Points
DART data inversion with new Green's functions produces slip distribution similar to joint inversion
Inversion of near‐field DART data can be used for real‐time tsunami forecast at far field
Tsunami source can be accurately estimated from far‐field DART data only
•An improved cellular automaton model for simulating debris flow run-out extent is proposed.•Flow routing algorithm is enhanced by additionally considering the effect of bed roughness.•Hydrodynamic ...model with sink-filling approach and sediment entrainment function is incorporated.•The 2010 Yohutagawa event in Japan is selected as a case study to verify the model.
As for late, studies have indicated that cellular automaton (CA) models are among the most effective solutions for simulating the extent of debris-flow run-out. However, it is currently difficult to effectively simulate both the inundated area and the erosion pattern of the debris flow process. This difficulty is caused by the lack of detailing regarding debris flow hydrodynamics as the primary concern of most CA-based models is the topographic gradient of the gully. In this study, we propose a two-dimensional Monte Carlo simulation-based CA model with hydrodynamic methods describing debris-flow behavior to address these problems. Herein, a topography function concerning slope gradient and bed roughness, and a persistence function regarding flow inertia, are combined to improve the flow routing algorithm for better determining the run-out extent of debris flow. Hydraulic links and discharge exchange between neighboring cells using sink-filling approach, as well as the bed sediment entrainment function, are incorporated into the CA model to describe the mass migration process along the flow path. To verify the performance of our proposed model, we further select the 2010 Yohutagawa debris flow event in Japan as a case study. The results indicate that the proposed model better simulates the complex dynamic process of debris flow.
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The shallow depth underthrust earthquake of February 27, 2010 (Mw 8.8) ruptured the subduction plate interface in central Chile between 34°S and 38°S. We retrieve the spatial and temporal ...distribution of slip during this mega‐earthquake through a joint inversion of teleseismic records, InSAR and High Rate GPS (HRGPS) data. Additionally, our model is shown to agree with broadband surface waves. Rupture initiated at about 32 km depth and propagated bilaterally resulting in two main slip zones located SSW and NNE of the hypocenter. Nucleation did not take place within or at the edge of one of these main asperities, but in between. During the first 30s, slip propagated predominantly southwards. Later on, the rupture evolved more slowly and more symmetrically. Eventually, the northern asperity became predominant with maximum slip reaching about 20 m. Most of the seismic moment was released within 110s, a relatively short time, explained by the bilateral propagation. The overall average rupture velocity is 2.6 km/s but propagation occurred initially faster towards the south (3.2 km/s). Large slip did not reach the trench, a result consistent with the moderate size of the tsunami. Down‐dip, rupture stopped at about 50 km depth, in agreement with the lower limit of the locked zone inferred by Ruegg et al. (2009) from pre‐seismic GPS data.
Transition from the Soviet type of economy to a new market system showed the necessity in reforms at the secondary school level. Based on a literature review, this paper aims to reveal how the ...thinking about teaching economics has changed over the past three decades (1991-2021),and how this has affected teaching economics as a school subject in the Post-Soviet countries. The article illustrates these with the cases of Russia and Kazakhstan. For this paper, a narrative literature review methodology was adopted, and scanned studies included only those published in English and Russian
In the paper, the impact on durability of polymer electrolyte membrane fuel cells is investigated when varying operating conditions applied in accelerated stress tests. By this, the electric ...potential cycling protocol in given by a non-symmetric square profile. The electrochemical degradation of a catalyst layer is caused by platinum ion dissolution and oxide coverage. These mechanisms are described by the one-dimensional Holby–Morgan model with a modified Butler–Volmer equation for the reaction rates. For efficient numerical solution of the underlying nonlinear reaction-diffusion system, a variable time-step implicit-explicit method is suggested. Computer simulations predict durability for the catalyst by using a linear extrapolation up to the full platinum surface blockage. A parameter sensitivity analysis is presented on different time scales and measures how the platinum mass loss is impacted by the variation of specific parameters.
•1D Holby-Morgan model of platinum electrochemical degradation is applied.•The catalyst degradation is computed at non-symmetric square voltage cycling.•Simulations predict lifetime of Pt catalyst in low temperature PEM fuel cells.•Variance-based analysis of operating conditions on Pt mass loss is carried out.•Low temperature and ionomer ratio, high acidity and Pt size increase lifetime.
Efforts to move the Capital of Indonesia to Kalimantan are intended to solve the problem of overpopulation in Jakarta, so it’s possible there are massive infrastructure development in the future. In ...this study conducted Probabilistic Seismic Hazard Analysis (PSHA) and made an earthquake hazard map that serves to analyze earthquake-resistant buildings for the New Capital of Indonesia. The PSHA and earthquake map was developed for 2% probability exceeded in 50 years or 2500-return period. The results of the analysis on three important periods, comprised of PGA, Ss, and S1 with a return period of 2500 years have higher acceleration at bedrock if performed by GMPE 2017 rather than GMPE 2010 for the period between PGA and 0.1s. Maximum earthquake acceleration on bedrock resulting from the creation of earthquake hazard maps in New Capital of Indonesia for period of PGA, 0.2s, and 1.0s at bedrock for return period of 2500 years is 0.2-0.25g, 0.4-0.5g, and 0-0.15g, respectively. The earthquake threat index in the New Capital of Indonesia is categorized as low according to Indonesia's National Board for Disaster Management (BNPB) regulations (PGA<0.2501g).
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