Pozzolanic reaction of volcanic ash with hydrated lime is thought to dominate the cementing fabric and durability of 2000-year-old Roman harbor concrete. Pliny the Elder, however, in first century CE ...emphasized rock-like cementitious processes involving volcanic ash (pulvis) "that as soon as it comes into contact with the waves of the sea and is submerged becomes a single stone mass (fierem unum lapidem), impregnable to the waves and every day stronger" (Naturalis Historia 35.166). Pozzolanic crystallization of Al-tobermorite, a rare, hydrothermal, calcium-silicate-hydrate mineral with cation exchange capabilities, has been previously recognized in relict lime clasts of the concrete. Synchrotron-based X-ray microdiffraction maps of cementitious microstructures in Baianus Sinus and Portus Neronis submarine breakwaters and a Portus Cosanus subaerial pier now reveal that Al-tobermorite also occurs in the leached perimeters of feldspar fragments, zeolitized pumice vesicles, and in situ phillipsite fabrics in relict pores. Production of alkaline pore fluids through dissolution-precipitation, cation-exchange and/or carbonation reactions with Campi Flegrei ash components, similar to processes in altered trachytic and basaltic tuffs, created multiple pathways to post-pozzolanic phillipsite and Al-tobermorite crystallization at ambient seawater and surface temperatures. Long-term chemical resilience of the concrete evidently relied on water-rock interactions, as Pliny the Elder inferred. Raman spectroscopic analyses of Baianus Sinus Al-tobermorite in diverse microstructural environments indicate a cross-linked structure with Al3+ substitution for Si4+ in Q3 tetrahedral sites, and suggest coupled Al3++Na+ substitution and potential for cation exchange. The mineral fabrics provide a geoarchaeological prototype for developing cementitious processes through low-temperature rock-fluid interactions, subsequent to an initial phase of reaction with lime that defines the activity of natural pozzolans. These processes have relevance to carbonation reactions in storage reservoirs for CO2 in pyroclastic rocks, production of alkali-activated mineral cements in maritime concretes, and regenerative cementitious resilience in waste encapsulations using natural volcanic pozzolans.
Lithium–sulfur (Li–S) batteries are considered as promising next‐generation energy storage devices due to their ultrahigh theoretical energy density, where soluble lithium polysulfides are crucial in ...the Li–S electrochemistry as intrinsic redox mediators. However, the poor mediation capability of the intrinsic polysulfide mediators leads to sluggish redox kinetics, further rendering limited rate performances, low discharge capacity, and rapid capacity decay. Here, an organodiselenide, diphenyl diselenide (DPDSe), is proposed to accelerate the sulfur redox kinetics as a redox comediator. DPDSe spontaneously reacts with lithium polysulfides to generate lithium phenylseleno polysulfides (LiPhSePSs) with improved redox mediation capability. The as‐generated LiPhSePSs afford faster sulfur redox kinetics and increase the deposition dimension of lithium sulfide. Consequently, the DPDSe comediator endows Li–S batteries with superb rate performance of 817 mAh g−1 at 2 C and remarkable cycling stability with limited anode excess. Moreover, Li–S pouch cells with the DPDSe comediator achieve an actual initial energy density of 301 Wh kg−1 and 30 stable cycles. This work demonstrates a novel redox comediation strategy with an effective organodiselenide comediator to facilitate the sulfur redox kinetics under pouch cell conditions and inspires further exploration in mediating Li–S kinetics for practical high‐energy‐density batteries.
An organodiselenide, diphenyl diselenide (DPDSe), is proposed to accelerate the sulfur redox kinetics as a redox comediator, which endows Li–S batteries with superb rate performance, remarkable cycling stability, and high actual energy density of 301 Wh kg−1. This work demonstrates a novel redox comediation strategy to facilitate the sulfur redox kinetics under practical pouch cell conditions.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
One of the most significant discoveries resulting from the sequencing of the human genome is the realization that a large portion (over 85%) of the genome is transcribed into RNA, yet less than 2% of ...it encodes protein-coding genes ...
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Energy is an important resource for human society and plays an important role in the development of society. However, due to the growing demand for energy in many countries around the world, the ...consumption of traditional fossil fuels such as coal is accelerating lead to problems such as resource scarcity, environmental pollution, and energy crisis are becoming increasingly prominent, which greatly restricts the sustainable development of the economy and human society, especially in areas where the utilization rate of new and renewable energy is not high. In order to realize environmental design and reduce pollution and solve problems such as resource shortages, this paper studies the utilization of new energy based on environmental design and realization. The experimental results show that the research on new energy based on environmental design and implementation can improve the utilization efficiency of new energy by 5.31%. This eases the future energy crisis and enables new energy to gradually replace solid resources such as fossil fuels as the main energy consumption. It can also solve the problem of energy shortage, reduce the waste and pollution of old energy in the environment, and improve the protection of the environment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We introduce a categorical construction of Harder–Narasimhan filtration via a slope method which does not need a degree function. With a theorem of existence and uniqueness of Harder–Narasimhan ...filtration in our categorical setting, we give a categorical interpretation of Stuhler–Grayson filtration in the case of not necessarily Hermitian normed lattices.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Cellulose is one of the most abundant bio-renewable materials on the earth and its conversion to biofuels provides an appealing way to satisfy the increasing global energy demand. However, before ...carrying out the process of enzymolysis to glucose or polysaccharides, cellulose needs to be pretreated to overcome its recalcitrance. In recent years, a variety of ionic liquids (ILs) have been found to be effective solvents for cellulose, providing a new, feasible pretreatment strategy. A lot of experimental and computational studies have been carried out to investigate the dissolution mechanism. However, many details are not fully understood, which highlights the necessity to overview the current knowledge of cellulose dissolution and identify the research trend in the future. This perspective summarizes the mechanistic studies and microscopic insights of cellulose dissolution in ILs. Recent investigations of the synergistic effect of cations/anions and the distinctive structural changes of cellulose microfibril in ILs are also reviewed. Besides, understanding the factors controlling the dissolution process, such as the structure of anions/cations, viscosity of ILs, pretreatment temperature, heating rate,
etc.
, has been discussed from a structural and physicochemical viewpoint. At the end, the existing problems are discussed and future prospects are given. We hope this article would be helpful for deeper understanding of the cellulose dissolution process in ILs and the rational design of more efficient and recyclable ILs.
This perspective summarizes mechanistic studies on cellulose dissolution in ionic liquids, highlighting the synergistic mechanism, physicochemical aspects and future research trends.
•We investigate extralocal interactions in intercity innovation networks.•We identify six major stylized facts of intercity innovation network in China.•Degree centrality and structural holes ...positively affect city innovation.•We explore the difference between the network of different collaboration types.•City innovation is enhanced when deeply embedded in intercity innovation networks.
This research investigates the impact of extralocal interactions in intercity coinvention networks on innovation in cities. Adopting a social network lens, we argue that the innovation performance of a city hinges on its centrality in intercity coinvention networks, its ability to fill structural holes in these networks, and its node cohesiveness and transitivity within ego networks. Using a unique longitudinal data set of patents granted from 2001 to 2016 in China, we construct two types of networks—those involving collaborations among universities as well as research institutes (URI) and those involving industry actors only (II)—and identify six major stylized facts in regards to the formation of a complex intercity innovation network within China’s national innovation system. A random-effects negative binomial regression model reveals positive effects of the degree centrality and structural holes variables on urban innovation in both URI and II networks, while a fixed-effects model suggests that the effects are only significant for II networks. Our study confirms that city innovation not only is determined by local innovative activities but also is enhanced when cities are deeply embedded in intercity innovative networks.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
To enhance the performance of the navigation system under the complex underwater environment, a hybrid interacting multiple model (HIMM) aided inertial navigation system (INS)/Doppler velocity logs ...(DVL) integration solution is proposed. First, to employ the acoustic Doppler current profiler mode of DVL, a novel INS/DVL mechanism is constructed where the water current velocity is estimated in real time and both bottom-track and water-track velocity measurements of DVL are involved in the observation vector. Meanwhile, to deal with the outliers and observation noises in the DVL's measurements, a HIMM algorithm is proposed to adaptively select the proper models to describe the changing environment. Simulations and field test are conducted to evaluate the effectiveness of the proposed algorithm, where the interacting multiple model (IMM) algorithm is employed for comparison. The results indicate that the proposed HIMM-aided INS/DVL integration solution shows superiority than the traditional IMM method when the observation noises and outliers exist. Meanwhile, the proposed integration scheme can successfully bridge the DVL's bottom-track outages.
This study explores the extent to which changes in transport infrastructure counterbalance pre-existing geographical friction and foster innovation collaboration, using the Chinese high-speed rail ...(HSR) construction as a quasi-natural experiment. Using a comprehensive dataset of city-pair co-patents from 2005 to 2018, we show that HSR connections significantly increase intercity co-patents, patent quality and collaborative partnerships, and such effects are strongest for city-pairs within 250 km and decrease for longer distances. Moreover, the HSR effect is stronger for cities in similar institutional settings, indicating a negative moderating effect of institutional distance. Various robustness methods are used to confirm the validity of our findings.
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BFBNIB, IZUM, KILJ, NUK, PILJ, SAZU, UL, UM, UPUK
Most scholarship on contentious politics in authoritarian regimes focuses on severe repression and transgressive protest (e.g. revolt), suggesting a zero-sum game played by the state and challengers. ...However, a burgeoning literature suggests that less brutal forms of authoritarian states have emerged in recent decades and that protesters in these countries tend to limit their challenges, avoiding direct confrontation with the authorities. If so, can the notion of the zero-sum game truly capture the nuances and complexities of contentious politics in authoritarian regimes? Taking the case of China, this article offers a systematic analysis of the pattern of repression and protest in a strong authoritarian state. Drawing on an original data set of 1,418 protest events in China, this article shows that the Chinese state permits some (albeit limited) space for protest and that most protesters confine themselves to this space. These findings thus provide quantitative evidence that popular contention in China is featured by a non-zero-sum game. Overall, this study contributes to a more comprehensive and complex understanding of popular contention in authoritarian settings.
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