The past decade has seen the development of microporous materials (i.e., materials containing pores of dimensions <2 nm) derived wholly from organic components. Here we review this nascent area with ...a particular emphasis on amorphous polymers that possess intrinsic microporosity (IM), which is defined as microporosity that arises directly from the shape and rigidity of component macromolecules. Although IM can be readily identified within soluble non-network polymers and oligomers, for network polymers it is harder to differentiate IM from template effects that are responsible for the microporosity within hyper-cross-linked networks. The numerous examples of microporous polymers assembled from rigid monomers by the formation of rigid linking groups are surveyed and their IM assessed. The potential applications of these materials are highlighted.
We report the preparation of a furan polymer, poly(2,5-furandimethylene succinate) by means of a condensation reaction between bio-based monomers. A reversible Diels–Alder reaction between furan and ...maleimide groups allowed the formation of network polymers cross-linked by a bismaleimide. By controlling the amount of the bismaleimide, mechanical properties were varied widely. These network polymers healed well when their broken surfaces were activated by bismaleimide solutions or solvent. The polymers also displayed excellent self-healing ability without external stimulus. This polymer class offers a wide range of possibilities to produce materials from biomass that have both practical mechanical properties and healing ability. These materials have the potential to bring great benefits to our daily lives by enhancing the safety, performance, and lifetime of products.
Polymer networks possessing reversible covalent cross-links constitute a novel material class with the capacity for adapting to an externally applied stimulus. These covalent adaptable networks ...(CANs) represent a trend in polymer network fabrication toward the rational design of structural materials possessing dynamic characteristics for specialty applications. Herein, we discuss the unique attributes of CANs that must be considered when designing, fabricating, and characterizing these smart materials that respond to either thermal or photochemical stimuli. While there are many reversible reactions which to consider as possible cross-link candidates in CANs, there are very few that are readily and repeatedly reversible. Furthermore, characterization of the mechanical properties of CANs requires special consideration owing to their unique attributes. Ultimately, these attributes are what lead to the advantageous properties displayed by CANs, such as recyclability, healability, tunability, shape changes, and low polymerization stress. Throughout this Perspective, we identify several trends and future directions in the emerging field of CANs that demonstrate the progress to date as well as the essential elements that are needed for further advancement.
THE DEPOSITS CHANNEL OF MONETARY POLICY Drechsler, Itamar; Savov, Alexi; Schnabl, Philipp
The Quarterly journal of economics,
11/2017, Volume:
132, Issue:
4
Journal Article
Peer reviewed
Open access
We present a new channel for the transmission of monetary policy, the deposits channel. We show that when the Fed funds rate rises, banks widen the spreads they charge on deposits, and deposits flow ...out of the banking system. We present a model where this is due to market power in deposit markets. Consistent with the market power mechanism, deposit spreads increase more and deposits flow out more in concentrated markets. This is true even when we control for lending opportunities by only comparing different branches of the same bank. Since deposits are the main source of liquid assets for households, the deposits channel can explain the observed strong relationship between the liquidity premium and the Fed funds rate. Since deposits are also a uniquely stable funding source for banks, the deposits channel impacts bank lending. When the Fed funds rate rises, banks that raise deposits in concentrated markets contract their lending by more than other banks. Our estimates imply that the deposits channel can account for the entire transmission of monetary policy through bank balance sheets.
This paper presents the optimal hybrid power system design including various configurations of renewable energy generation. To decide the optimal configuration of parameters a new multi-objective ...function with six separate objectives of hybrid renewable system is presented using GA, PSO, BFPSO and TLBO optimization techniques. The different parameters namely technical (LPSP, Renewable factor), economical (COE, Penalty & Fuel consumption) and social (Job creation, HDI & PM) features are investigated as objectives simultaneously for optimal design of hybrid system. The design consideration of hybrid system using a novel PM factor, human health impacts are directly shown whereas pollutant emission is measured in the hybrid system design. Based on the minimum value of multi-objective function optimal values are decided for objective indices. For optimal configuration including various combinations of wind, PV, diesel generator, biomass and battery bank, separate cases from I to VI of hybrid system are tested. Performance of TLBO is found to be better than BFPSO, PSO and GA as per the analysis of results for individual cases. Also the case I found to be the most efficient solution among all cases.
•Modelling of PV, Wind and Biomass.•Considered the effect of Variable Speed Diesel Generator (VSDG).•Hybrid renewable System design criteria with economic, technical and social effect.•Particular Matter (PM) is calculated for the design of hybrid system.•Investigation of human development index and job creation factor for optimal design of hybrid renewable system.
Nanoporous organic polymer networks Dawson, Robert; Cooper, Andrew I.; Adams, Dave J.
Progress in polymer science,
2012, Volume:
37, Issue:
4
Journal Article
Peer reviewed
Nanoporous organic polymer networks are a class of materials consisting solely of the lighter elements in the periodic table. These materials have potential uses in areas such as storage, separation, ...and catalysis. Here, we review the different classes of nanoporous polymer networks including covalent organic frameworks, hypercrosslinked polymers, conjugated microporous polymers, and polymers of intrinsic microporosity. The growing variety in synthetic routes to these materials allows a range of different polymer networks to be formed, including crystalline and amorphous structures. It is also possible to incorporate many different kinds of functional groups in a modular fashion. So far, most networks have been examined from the perspective of gas sorption, and this area is discussed critically and in depth in this review. The use of nanoporous organic polymers for applications such as catalysis and separations is an important developing area, and we discuss recent developments as well as highlighting potential future opportunities.
The U.S. Department of Energy’s Co-Optima initiative has focused on improving fuel economy and vehicle performance while reducing emissions through the simultaneous development of emerging ...sustainable fuels with beneficial properties and advanced combustion strategies. A major thrust has been the development of advanced compression ignition (ACI) combustion strategies of gasoline range fuels in combination with spark-ignited (SI) combustion in a single engine capable of multi-mode operation to achieve high power density with enhanced part load efficiency. The aim of this study was to further the understanding of how emissions from both ACI and SI strategies operating on the same fuels in the same engine are impacted by different fuel properties. This investigation focused on particulate matter (PM) and gaseous hydrocarbon emissions from 6 different fuels across 3 different combustion modes on the same single-cylinder engine designed for multi-mode operation: SI combustion, partial fuel stratification (PFS), and spark-assisted compression ignition (SACI). In each of these modes, 3 different CA50 phasings were studied such that all 6 fuels could be studied at the same phasings. Three of the six different fuels used were specially formulated in a previous investigation to study the impact of fuel distillation and aromatic content while maintaining the research octane number (RON) and octane sensitivity. Additionally, neat isooctane and two ethanol containing fuels (RD5-87 and Co-Optima E30) were studied. Different fuel and phasing impacts on emissions were observed across the three combustion modes. Fuel properties were found to impact soot PM and particle number more than the CA50 phasing, while the phasing had more impact on NOx emissions. The NOx emissions were reduced in the PFS mode for all fuels compared to SI combustion, but the SACI combustion mode did not reduce NOx emissions. Although PFS produced low soot PM emissions like SI, total PM mass emissions were significantly higher due to large organic carbon (OC) PM mass contribution. Both PFS and SACI had greater particle number emission than SI operation with small nuclei mode particles dominating in PFS compared to large agglomeration particles in SACI.
This review highlights the functionalization chemistry of graphene with polymers by both covalent and non-covalent approaches. Due to the strong cohesive interactions graphene platelets agglomerate, ...causing difficulty to attain its optimum properties. The covalent functionalization is illuminated both from ‘grafting to’ and ‘grafting from’ techniques discussing the merits and demerits of the processes. The controlled free radical polymerization techniques used for this purpose e.g. ATRP, SET–LRP and RAFT etc. are discussed along with the conventional free radical polymerization. We have also noted the various approaches used in non-covalent functionalization e.g. π–π, H-bonding and hydrophobic interactions. These functionalized graphenes show good and stable dispersion facilitating composite formation with commodity plastics enhancing it's mechanical, thermal and conductivity properties. The optoelectronic properties of these functionalized graphene are interesting to fabricate sensors, photovoltaics, supercapacitors etc. A short account of the properties of these modified graphenes is also embodied with an emphasis on different area where future developments are expected.
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The ability to design and assemble three-dimensional structures from colloidal particles is limited by the absence of specific directional bonds. As a result, complex or low-coordination structures, ...common in atomic and molecular systems, are rare in the colloidal domain. Here we demonstrate a general method for creating the colloidal analogues of atoms with valence: colloidal particles with chemically distinct surface patches that imitate hybridized atomic orbitals, including sp, sp(2), sp(3), sp(3)d, sp(3)d(2) and sp(3)d(3). Functionalized with DNA with single-stranded sticky ends, patches on different particles can form highly directional bonds through programmable, specific and reversible DNA hybridization. These features allow the particles to self-assemble into 'colloidal molecules' with triangular, tetrahedral and other bonding symmetries, and should also give access to a rich variety of new microstructured colloidal materials.
Large and growing literature has explored whether temperature modified the effect of particular matter (PM) on mortality, but results of the modification effect are inconsistent. In this study, we ...reviewed information from 29 studies to get the qualitative evidence of the modification effects of temperature on PM to mortality, and the data from 16 of the 29 studies were extracted to conduct a meta-analysis. Temperatures were grouped into three level: “low”, “middle” and “high” according to the original studies. The random effect model was used in the meta-analysis with the relative risk (RR) as the measure indicator. The RRs (95% confidence intervals, CIs) for non-accidental death, cardiovascular death and respiratory death per 10 μg/m3 increase in PM10 were 1.004 (1.003, 1.006), 1.005 (1.003,1.007), and 1.005 (1.000,1.010) in the low temperature level, 1.005 (1.004,1.006), 1.005 (1.004,1.007), and 1.008 (1.006, 1.010) in the middle temperature level, and 1.012 (1.010, 1.015), 1.016 (1.010, 1.022) and 1.019 (1.010,1.028) in the high temperature level, respectively. In conclusion, moderate evidence exists that temperature modifies the effect of PM10 on mortality. The effect of PM10 on respiratory death was the greatest, while the effect on non-accidental death was the smallest in the same temperature level. In addition, the effects of PM10 on all the three kinds of mortality were the biggest in the high-temperature level, and the smallest in the low-temperature level.
•The effect of PM10 on respiratory death was the greatest in the same temperature level.•Effects of PM10 on mortality were the biggest in the high temperature level, and the smallest in the low temperature level.•Policy makers should enhance the emission control of PM10 in high temperature days.•Product term, stratification and bivariate response surfaces are three main methods to explore the interaction effects.•There should be a standard method to select cut-offs of air pollutants and meteorological factors.
The effect of PM10 on respiratory death was the greatest in same temperature level, and the effects on all three kinds of mortality were the biggest in the high-temperature level.
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