scholarly journals Hierarchical Porous Polyamide 6 by Solution Foaming: Synthesis, Characterization and Properties

Polymers ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1310 ◽  
Author(s):  
Liang Wang ◽  
Yu-Ke Wu ◽  
Fang-Fang Ai ◽  
Jie Fan ◽  
Zhao-Peng Xia ◽  
...  
Keyword(s):  
Large Scale ◽  
Polyamide 6 ◽  
Solution Concentration ◽  
The Novel ◽  
Foaming Agent ◽  
Hierarchical Porous ◽  
Wide Range ◽  
The Mean ◽  
Novel Strategy

Porous polym er materials have received great interest in both academic and industrial fields due to their wide range of applications. In this work, a porous polyamide 6 (PA6) material was prepared by a facile solution foaming strategy. In this approach, a sodium carbonate (SC) aqueous solution acted as the foaming agent that reacted with formic acid (FA), generating CO2 and causing phase separation of polyamide (PA). The influence of the PA/FA solution concentration and Na2CO3 concentration on the microstructures and physical properties of prepared PA foams were investigated, respectively. PA foams showed a hierarchical porous structure along the foaming direction. The mean pore dimension ranged from hundreds of nanometers to several microns. Low amounts of sodium salt generated from a neutralization reaction played an important role of heterogeneous nucleation, which increased the crystalline degree of PA foams. The porous PA materials exhibited low thermal conductivity, high crystallinity and good mechanical properties. The novel strategy in this work could produce PA foams on a large scale for potential engineering applications.

Events in Northern Africa and Middle East: Causes and Consequences

2011 ◽  
pp. 11-25
Author(s):  
I. Labinskaya
Keyword(s):  
Middle East ◽  
North Africa ◽  
Large Scale ◽  
Arab Countries ◽  
Northern Africa ◽  
External Factors ◽  
Wide Range ◽  
The Usa ◽  
Oriental Studies

Political developments in North Africa and the Middle East that have begun in January 2011 are gaining strength and involve an increasing number of Arab countries. The participants of the Roundtable – experts from IMEMO, Institute of Oriental Studies (RAS), Institute of the USA and Canada (RAS) and Mrs. E. Suponina from “Moscow News” newspaper analyzed a wide range of issues associated with these events. Among them are: 1) the reasons for such a large-scale explosion, 2) the nature of the discussed developments (revolutions, riots?) and who are the subjects of the current “Arab drama”, 3) the role of Islam and political Islamism, 4) the role of external factors.

scholarly journals The role of airborne volcanic ash for the surface ocean biogeochemical iron-cycle: a review

2009 ◽  
Vol 6 (4) ◽  
pp. 6441-6489 ◽  
Author(s):  
S. Duggen ◽  
N. Olgun ◽  
P. Croot ◽  
L. Hoffmann ◽  
H. Dietze ◽  
...  
Keyword(s):  
Large Scale ◽  
Volcanic Ash ◽  
Volcanic Eruptions ◽  
Research Field ◽  
Ash Deposition ◽  
Future Directions ◽  
Iron Cycle ◽  
Surface Ocean ◽  
Wide Range

Abstract. Iron is a key micronutrient for phytoplankton growth in the surface ocean. Yet the significance of volcanism for the marine biogeochemical iron-cycle is poorly constrained. Recent studies, however, suggest that offshore deposition of airborne ash from volcanic eruptions is a way to inject significant amounts of bio-available iron into the surface ocean. Volcanic ash may be transported up to several tens of kilometres high into the atmosphere during large-scale eruptions and fine ash may encircle the globe for years, thereby reaching even the remotest and most iron-starved oceanic areas. Scientific ocean drilling demonstrates that volcanic ash layers and dispersed ash particles are frequently found in marine sediments and that therefore volcanic ash deposition and iron-injection into the oceans took place throughout much of the Earth's history. The data from geochemical and biological experiments, natural evidence and satellite techniques now available suggest that volcanic ash is a so far underestimated source for iron in the surface ocean, possibly of similar importance as aeolian dust. Here we summarise the development of and the knowledge in this fairly young research field. The paper covers a wide range of chemical and biological issues and we make recommendations for future directions in these areas. The review paper may thus be helpful to improve our understanding of the role of volcanic ash for the marine biogeochemical iron-cycle, marine primary productivity and the ocean-atmosphere exchange of CO2 and other gases relevant for climate throughout the Earth's history.

Optimal energy growth in stably stratified turbulent Couette flow

2021 ◽  
Author(s):  
Grigory Zasko ◽  
Andrey Glazunov ◽  
Evgeny Mortikov ◽  
Yuri Nechepurenko ◽  
Pavel Perezhogin
Keyword(s):  
Boundary Layer ◽  
Turbulent Flow ◽  
Couette Flow ◽  
Large Scale ◽  
Thin Layers ◽  
Plane Couette Flow ◽  
Turbulent Layer ◽  
Wide Range ◽  
The Mean ◽  
Optimal Disturbances

<p>In this report, we will try to explain the emergence of large-scale organized structures in stably stratified turbulent flows using optimal disturbances of the mean turbulent flow. These structures have been recently obtained in numerical simulations of turbulent stably stratified flows [1] (Ekman layer, LES) and [2] (plane Couette flow, DNS and LES) and indirectly confirmed by field measurements in the stable boundary layer of the atmosphere [1, 2]. In instantaneous temperature fields they manifest themselves as irregular inclined thin layers with large gradients (fronts), spaced from each other by distances comparable to the height of the entire turbulent layer, and separated by regions with weak stratification.</p><p>Optimal disturbances of a stably stratified turbulent plane Couette flow are investigated in a wide range of Reynolds and Richardson numbers. These disturbances were computed based on a simplified linearized system of equations in which turbulent Reynolds stresses and heat fluxes were approximated by isotropic viscosity and diffusion with coefficients obtained from DNS results. It was shown [3] that the spatial scales and configurations of the inclined structures extracted from DNS data coincide with the ones obtained from optimal disturbances of the mean turbulent flow.</p><p>Critical value of the stability parameter is found starting from which the optimal disturbances resemble inclined structures. The physical mechanisms that determine the evolution, energetics and spatial configuration of these optimal disturbances are discussed. The effects due to the presence of stable stratification are highlighted.</p><p>Numerical experiments with optimal disturbances were supported by the RSF (grant No. 17-71-20149). Direct numerical simulation of stratified turbulent Couette flow was supported by the RFBR (grant No. 20-05-00776).</p><p>References:</p><p>[1] P.P. Sullivan, J.C. Weil, E.G. Patton, H.J. Jonker, D.V. Mironov. Turbulent winds and temperature fronts in large-eddy simulations of the stable atmospheric boundary layer // J. Atmos. Sci., 2016, V. 73, P. 1815-1840.</p><p>[2] A.V. Glazunov, E.V. Mortikov, K.V. Barskov, E.V. Kadantsev, S.S. Zilitinkevich. Layered structure of stably stratified turbulent shear flows // Izv. Atmos. Ocean. Phys., 2019, V. 55, P. 312–323.</p><p>[3] G.V. Zasko, A.V. Glazunov, E.V. Mortikov, Yu.M. Nechepurenko. Large-scale structures in stratified turbulent Couette flow and optimal disturbances // Russ. J. Num. Anal. Math. Model., 2010, V. 35, P. 35–53.</p>

scholarly journals MJO Simulation Diagnostics

2009 ◽  
Vol 22 (11) ◽  
pp. 3006-3030 ◽  
Keyword(s):  
Model Performance ◽  
Diagnostic Techniques ◽  
Life Cycles ◽  
Global Circulation ◽  
Orthogonal Function ◽  
Global Circulation Models ◽  
Wide Range ◽  
Weather And Climate ◽  
The Mean

Abstract The Madden–Julian oscillation (MJO) interacts with and influences a wide range of weather and climate phenomena (e.g., monsoons, ENSO, tropical storms, midlatitude weather), and represents an important, and as yet unexploited, source of predictability at the subseasonal time scale. Despite the important role of the MJO in climate and weather systems, current global circulation models (GCMs) exhibit considerable shortcomings in representing this phenomenon. These shortcomings have been documented in a number of multimodel comparison studies over the last decade. However, diagnosis of model performance has been challenging, and model progress has been difficult to track, because of the lack of a coherent and standardized set of MJO diagnostics. One of the chief objectives of the U.S. Climate Variability and Predictability (CLIVAR) MJO Working Group is the development of observation-based diagnostics for objectively evaluating global model simulations of the MJO in a consistent framework. Motivation for this activity is reviewed, and the intent and justification for a set of diagnostics is provided, along with specification for their calculation, and illustrations of their application. The diagnostics range from relatively simple analyses of variance and correlation to more sophisticated space–time spectral and empirical orthogonal function analyses. These diagnostic techniques are used to detect MJO signals, to construct composite life cycles, to identify associations of MJO activity with the mean state, and to describe interannual variability of the MJO.

Drivers of biases in the extratropical storm tracks in CMIP6

2020 ◽  
Author(s):  
Matthew Priestley ◽  
Duncan Ackerley ◽  
Jennifer Catto ◽  
Kevin Hodges ◽  
Ruth McDonald ◽  
...  
Keyword(s):  
Large Scale ◽  
Climate Models ◽  
Storm Track ◽  
Storm Tracks ◽  
Extratropical Cyclones ◽  
Ocean Coupling ◽  
Coupled Climate Models ◽  
The Mean ◽  
The Impact

<p>Extratropical cyclones are the leading driver of the day-to-day weather variability and wintertime losses for Europe. In the latest generation of coupled climate models, CMIP6, it is hoped that with improved modelling capabilities come improvements in the structure of the storm track and the associated cyclones. Using an objective cyclone identification and tracking algorithm the mean state of the storm tracks in the CMIP6 models is assessed as well as the representation of explosively deepening cyclones. Any developments and improvements since the previous generation of models in CMIP5 are discussed, with focus on the impact of model resolution on storm track representation. Furthermore, large-scale drivers of any biases are investigated, with particular focus on the role of atmosphere-ocean coupling via associated AMIP simulations and also the influence of large-scale dynamical and thermodynamical features.</p>

Understanding the Role of the Corporation in Sustainability Transitions

2019 ◽  
Vol 32 (2) ◽  
pp. 87-97 ◽  
Author(s):  
Magali A. Delmas ◽  
Thomas P. Lyon ◽  
John W. Maxwell
Keyword(s):  
Case Studies ◽  
Large Scale ◽  
Systemic Change ◽  
Coalition Building ◽  
Sustainability Transitions ◽  
Study Approach ◽  
Responsible Investing ◽  
Information Strategies ◽  
Wide Range

The state of the planet calls for large-scale sustainability transitions involving systemic adoption of markedly better environmental and social practices. The objective of this symposium is to better understand the role of corporations in promoting such systemic change. We present four case studies—representing diverse industries and change mechanisms—-to investigate corporate leadership in sustainability transitions. The cases examine a wide range of mechanisms used by corporations to progress toward sustainability, such as political coalition building and information strategies through eco-labels, socially responsible investing, and the public statements of CEOs. In this introduction, we discuss the challenges associated with both achieving and studying systemic change, explain the rationale for a case study approach, describe the findings from the case studies, and draw some general conclusions on the mechanisms by which firms may be able to lead, or at least participate in, systemic change in the different phases of sustainability transitions.

scholarly journals The Role of Biosurfactants in the Continued Drive for Environmental Sustainability

2018 ◽  
Vol 10 (12) ◽  
pp. 4817 ◽  
Author(s):  
Ibukun Olasanmi ◽  
Ronald Thring
Keyword(s):  
Environmental Sustainability ◽  
Large Scale ◽  
Environmental Pollutants ◽  
Waste Reduction ◽  
Industry Research ◽  
Wide Range ◽  
Low Toxicity ◽  
Microbial Products ◽  
Near Future

Biosurfactants are microbial products that have been increasingly researched due to their many identified advantages, such as low toxicity and high activity at extreme temperatures, but more importantly, they are biodegradable and compatible with the environment. Biosurfactants are versatile products with vast applications in the clean-up of environmental pollutants through biodegradation and bioremediation. They also have applications in the food, pharmaceutical, and other industries. These advantages and wide range of applications have led to the continued interest in biosurfactants. In particular, there is a growing discussion around environmental sustainability and the important role that biosurfactants will increasingly play in the near future, for example, via the use of renewable by-products as substrates, waste reduction, and potential reuse of the treated waste. This has resulted in increased attention on these microbial products in industry. Research highlighting the potential of biosurfactants in environmental sustainability is required to drive efforts to make biosurfactants more viable for commercial and large-scale applications; making them available, cheaper and economically sustainable. The present review discusses the unique relationship between biosurfactants and environmental sustainability, especially the role that biosurfactants play in the clean-up of environmental pollutants and, therefore, increasing environmental protection.

THERMODYNAMICS OF THE FERMI-LINEARIZED EXTENDED HUBBARD MODEL

1992 ◽  
Vol 06 (22) ◽  
pp. 3529-3541 ◽  
Author(s):  
ANDREA DANANI ◽  
ARIANNA MONTORSI ◽  
MARIO RASETTI
Keyword(s):  
Hubbard Model ◽  
Coulomb Interaction ◽  
Mean Field ◽  
Local Magnetic Moment ◽  
The Novel ◽  
Extended Hubbard Model ◽  
Site Cluster ◽  
The Mean ◽  
Two Phases

The fermi linearization scheme for a two-site cluster (dimer) is applied to the extended Hubbard model, including Coulomb interaction between nearest neighbour sites. The partition function and the order parameter, as well as the average double-occupation and local magnetic moment are evaluated. The theory is checked by extended numerical analysis, performed here in the homogeneous case, when pairing is zero, and deriving the explicit temperature and filling dependence of the above quantities. An interesting feature that emerges from such calculations is that the mean-field parameter characteristic of fermi-linearization is capable of describing two different phases, one of which is not present in the conventional Hubbard model. The order parameters corresponding to the two phases are explicitly derived. The novel phase can be ascribed to the n.n. Coulomb interaction, the role of whose strength V is analysed.

A novel porA-based real-time PCR for detection of meningococcal carriage

2005 ◽  
Vol 54 (5) ◽  
pp. 463-466 ◽  
Author(s):  
J Zoe Jordens ◽  
John E Heckels
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Large Scale ◽  
Taqman Assay ◽  
Meningococcal Infection ◽  
Specific Method ◽  
The Novel ◽  
Wide Range ◽  
Taqman Pcr ◽  
Neisseria Sicca

Real-time PCR based on the capsule transfer gene (ctrA) is a significant aid in the diagnosis of meningococcal infection but fails to detect a high proportion (60 %) of non-groupable strains associated with nasopharyngeal carriage. This study aimed to design a novel real-time (TaqMan) PCR that would detect more strains of meningococci and be suitable for large-scale carriage studies. Primer and probe sequences were based on the meningococcal porA gene and designed specifically to exclude the highly related porA pseudogene in Neisseria gonorrhoeae. The specificity of the assay was confirmed by testing strains of N. gonorrhoeae known to contain the porA pseudogene together with commensal strains of Neisseria lactamica and Neisseria sicca. None of these was detected in the assay. Neisseria meningitidis strains representing a wide range of serogroups together with non-groupable strains isolated from the nasopharynx were tested by ctrA assay and the novel porA-based TaqMan PCR. All carriage strains were detected by the porA-based assay including four that gave weak or no reaction with the ctrA assay. Comparison of ctrA and porA assays on 71 throat swabs obtained from university students showed that the porA assay detected meningococcal DNA in all samples that were ctrA positive plus three that were ctrA negative but culture positive. This novel porA-based TaqMan assay provides a highly specific method for detecting meningococcal DNA that is more sensitive than the ctrA assay for detecting meningococcal carriage and is particularly suitable for carriage studies where non-groupable strains and other Neisseria are present.

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