Rapid Temperature Increase Research Articles

Micro- and mesozooplankton successions in an Antarctic coastal environment during a warm year.

The rapid increase in atmospheric temperature detected in the last decades in the Western Antarctic Peninsula was accompanied by a strong glacier retreat and an increase in production of melting water, as well as changes in the sea-ice dynamic. The objective of this study was to analyze the succession of micro- and mesozooplankton during a warm annual cycle (December 2010-December 2011) in an Antarctic coastal environment (Potter Cove). The biomass of zooplankton body size classes was used to predict predator-prey size relationships (i.e., to test bottom-up/top-down control effects) using a Multiple Linear Regression Analysis. The micro- and mesozooplanktonic successions were graphically analyzed to detect the influence of environmental periods (defined by the degree of glacial melting, sea-ice freezing and sea-ice melting) on coupling/uncoupling planktonic biomass curves associated to possible predator-prey size relationship scenarios. At the beginning of the glacial melting, medium and large mesozooplankton (calanoid copepods, Euphausia superba, and Salpa thompsoni) exert a top-down control on Chl-a and microzooplankton. Stratification of the water column benefitted the availability of adequate food-size (Chl-a <20) for large microzooplankton (tintinnids) development observed during fall. High abundance of omnivores mesozooplankton (Oithona similis and furcilia of E. superba) during sea-ice freezing periods would be due to the presence of available heterotrophic food under or within the sea ice. Finally, the increase in microzooplankton abundance in the middle of spring, when sea-ice melting starts, corresponded to small and medium dinoflagellates and ciliates species, which were possibly part of the biota of sea ice. If glacier retreat continues and the duration and thickness of the sea ice layer fluctuates as predicted by climate models, our results predict a future scenario regarding the zooplankton succession in Antarctic coastal environments.

Quantification of the effect of Cr-coated-Zircaloy cladding during a short term station black out

Accident Tolerant Fuel (ATF) has the potential to improve the inherent safety of current reactors. In particular, an ATF Cr-coated Zirconium alloy (Cr-coated-Zr) cladding can be an effective short-term approach to improve the cladding oxidation resistance without changing the cladding base materials. In order to appropriately assess the effect of such an ATF concept it is important to quantify the performance of such a cladding improvement not only during normal operation but also during postulated accidents. In this work, we examine the effect of Cr-coated-Zr cladding (Cr-Zr) during a short-term station blackout (STSBO) accident as well as quantify the uncertainty in the use of ATF Cr-coated-Zr cladding. This is accomplished using a coated cladding model developed for the MELCOR severe accident systems code; i.e., MELCOR-1.8.6-UDGC model. First, we quantify the effect of the coated cladding using a set of base case simulations that show the improved oxidation resistance of the Cr-coated-Zr cladding with the UDGC model parameters. Then, we quantify the uncertainty in these simulations by a Monte-Carlo analysis that examines the effect of the ATF clad input parameters (e.g., oxidation rate and failure temperature) on key output parameters; i.e., timing of rapid hydrogen generation, clad temperatures and hot leg creep rupture. Finally, we use regression analysis methods to estimate the importance of these input parameters. These analyses show that the Cr-coated-Zr cladding can delay rapid clad oxidation and generation of hydrogen by 3600 s to 7200 s with associated delays in rapid clad temperature increases. This additional time can be of benefit for compensatory operator actions. In contrast there is little effect on the timing of hot leg creep rupture since this failure is mainly controlled by core decay heat. We also find that these results are not significantly affected by the uncertainty in input parameters, and based on the regression analysis, the high temperature Zr oxidation rate has the major influence on the selected output parameters for the Cr-coated-Zr cladding.

Nano carbides-mediated acceleration of energy release behavior of amorphous boron during ignition and combustion

Action mechanism of nano titanium carbide (nTiC), nano zirconium carbide (nZrC), and nano silicon carbide (nSiC) was studied using a concentrated ignition experimental system, an X-ray diffractometer and a scanning electron microscope. Each nano-carbide was mixed with B in mass ratio of 2/8 and then pressed into tablets, respectively. Furthermore, a sample of amorphous B was also prepared as the control group. All the three nano-carbides showed positive influence on the ignition of B. During the first stage of combustion, only nTiC could increase the maximum emission spectral intensity of the sample, while both nTiC and nZrC helped to increase that during the second stage of combustion. Although the addition of nano-carbides intensified the energy release rate of B (except nSiC), the expansion and diffusion of generated carbon dioxide took large amounts of heat away and reduced the surface temperature of the samples The temperature change in solid-phase exhibited a relationship with the spectral intensity change in gas-phase. The temperature increase was slow during the ignition delay stage, while the first combustion stage proceeded with rapid increase in surface temperature. The high-temperature areas regressed during the second combustion stage, accompanied by the gradual stopping of gas-phase reactions. The components and microstructure of the condensed combustion products (CCPs) were analyzed after the ignition experiment. Results showed that both nTiC and nZrC could react with B to generate corresponding metal borides, capable of promoting the ignition of B. Moreover, the catalysis of produced TiO2 and ZrO2 explain the increase of emission spectral intensity during the second combustion stage. A lot of micropores formed in the CCPs after adding nTiC, which showed a destructive effect of generated gaseous CO2 on the surface oxide layer. In general, nTiC is the top accelerant for B oxidation in this study, while nSiC is at the bottom.

Optical Defects Engineering of Metal Oxide Nanosheets Toward Exceptional Chemiresistor

Metal oxide nanosheets (NSs) exhibit intriguing physicochemical properties such as high specific surface area, high fraction of reaction sites, thus leading to promising performance in various applications including energy storage, catalysis, and gas sensing. [1] Beyond the 2D metal oxide NSs, defect engineering and/or control of non-stoichiometry, that is, control of metal or oxygen vacancies, are a few of the powerful strategies to generate abundant active sites to enhance gas sensing performance. [2] Precise control of the heat treatment, ramping rate control or reducing heat treatment as examples, is an effective way to generate the oxygen vacancies, but is time-consuming which requires high thermal-budget. Building-up of hetero-junctions is another powerful method to boost up the sensing performance. [3] However, it has been a challenge to prepare thin-layered heterogeneous metal oxide NSs with abundant active defect sites.An optical engineering to generate controllable oxygen vacancies and new crystal phases on various metal oxide nanosheets (NSs) is introduced via graphene oxide (GO) templating route followed by intense pulsed light (IPL) irradiation. Negatively charged GO flakes and metal ions readily self-assemble to form GO@M (where M = Sn2+, Co2+, Ti4+, and Zn2+) and polycrystalline metal oxide NSs, such as SnO2, Co3O4, TiO2, and ZnO, are successfully synthesized after calcination. Upon a few flashes of IPL irradiation (< 20 ms), a rapid increase in temperature (1200 °C) has induced evolution of defect sites and new crystal phases. As a representative, optically treated Pt-SnO2 NSs showed unparalleled formaldehyde (HCHO) response, excellent selectivity, low detection limit (100 ppb), and fast response speed (< 10 s) assisted by the synergistic effects of the Pt catalysts, numerous oxygen vacancies, and hetero-junctions formed by flash-induced partial reduction of n-type SnO2 to p-type SnO. This defects engineering method could greatly strengthen the design of various heterogeneous metal oxide NSs and their potential application toward various fields with the optimal customized physicochemical properties.

Physico-chemical and spectroscopic quality assessment of compost from date palm (Phoenix dactylifera L.) waste valorization

Organic matter (OM) is a vital component for a healthy soil, its lack arise a major problem for farmers who need to use commercialized fertilizers with high costs. Considering circular economy approach and for increasing OM availability, water soaked date palm waste was co-composted with goat manure in aerated windrow to produce a soil organic amendment. The OM biodegradation was mainly controlled based on biological parameters and spectroscopic techniques. The results showed a rapid temperature increase during the first week, and a relatively long compost maturity phase. The OM content reduction was of 36% and C/N ratio shifted from 60 to 20 at the process end. During the composting process, the specific ultraviolet absorbance SUVA254, SUVA269 and the SUVA280 values increase confirmed the OM and hydrophilic compounds degradation, as well as substrate content oxidation into aromatic compounds. The Fourier Transform Infrared Spectroscopy (FTIR) analyses of the different samples collected during the process exhibited both OM biodegradation and mineralization. The 3 absorption ratios 1650/2845, 1525/2925 and 2920/1640 confirmed an aromaticity increase by aromatic structures biosynthesis, such as humic-like and fulvic-like substances, with the decomposition/transformation of aliphatic components, polysaccharides, and alcohols. Fluorescence excitation-emission matrix (FEEM) spectroscopy coupled with parallel factor analysis (PARAFAC) evidenced the dissolved organic matter (DOM) humification. A four-component model was obtained, i.e. humic-like component (S1, S2 and S3) and fulvic-like component (S4). The produced compost didn't exhibit any phytotoxicity evidenced by cress seed germination index exceeding 80%. All the analyses confirmed the good quality of the compost issued from mixed date palm waste and goat manure.

A high-resolution Middle to Late Permian paleotemperature curve reconstructed using oxygen isotopes of well-preserved brachiopod shells

Climatic warming has been widely cited as a driver for many mass extinction events in Earth history, including the middle-late Permian Guadalupian-Lopingian boundary (GLB) mass extinction and end-Permian mass extinction (EPME) investigated in this study. However, the role of warming in driving the EPME event is under debate because current paleotemperature studies indicate the rapid increase in sea-surface temperature postdate the onset of the EPME event, and a reliable paleotemperature record across the GLB event is lacking. Here, we present a high-resolution and successive δ18O record using low-Mg calcite shells of brachiopods (bLMCs) from a single stratigraphic section in central China to reconstruct paleotemperature changes from the middle to the latest Permian. After a rigorous screening for diagenesis, our data show a ∼1.0‰ decrease in δ18Ocalcite (and thus climatic warming) during the middle Capitanian, followed by a gradual ∼2.0‰ increase (climatic cooling) during the late Wuchiapingian. From the latest Wuchiapingian to the early Changhsingian, δ18O decreased gradually and reached the lowest values of -4.0‰ (and thus rapid climatic warming) immediately before the Permian-Triassic boundary. The two warming events are coeval with the onset of the Emeishan Large Igneous Province and the Siberian Traps Large Igneous Province, respectively, suggesting the two volcanic events are the plausible drivers of these climatic warming events. A close comparison of paleontological and geochemical records indicates that the warming events occurred predate the GLB and EPME events, this is in contrast with conodont δ18Oapatite data which document the rapid climatic warming lagged the onset of the extinction event. The comparison between δ18O of bLMCs and δ18O of conodonts from the same section shows that the long-term trends are similar, but, at higher temporal resolution, discrepancies are present, entailing further investigation in the near future. Our study confirms that δ18O of the brachiopod shells underwent important changes during the end of Paleozoic, highlighting that sea surface temperature is a key factor to understand the biosphere history, since it changes simultaneously with the biological crises, and that bLMCs are invaluable archive for tracking physical and chemical conditions of past oceans.

Observation of Thermospheric Gravity Waves in the Southern Hemisphere With GOLD

AbstractThe middle thermosphere from ~150 to 250 km is characterized by rapid increase in temperature with altitude and rapid ionization. The entire thermosphere is believed to be home to atmospheric waves that propagate through it, originating both in the atmospheric layers below and in the thermosphere itself. Within the middle thermosphere, direct observations of such waves are extremely sparse. The Global‐scale Observations of the Limb and Disk (GOLD) far‐ultraviolet imaging spectrometer is able to observe the middle thermosphere from geostationary orbit. During October 2018, a special observational campaign was performed, designed to identify atmospheric waves. Signatures in the 135.6‐nm O airglow were seen that move northward with time, away from the southern polar region. These are consistent with a large‐scale atmospheric gravity wave. These results are the first time 135.6‐nm airglow has been used to track such a wave and highlight the ability of GOLD to observe such waves, even when at a modest amplitude, and track their motion.

Microwave based regenerating permeable reactive barriers (MW-PRBs): Proof of concept and application for Cs removal

The present study evaluates the concept of permeable reactive barrier (PRB) coupled with microwaves (MWs) as in situ-regenerating technology with focus on Cs-contaminated water. Experimental and modelling results data from batch and column tests were carried out, evaluating several chemical-physical and environmental parameters.Main results showed a very rapid increase in GAC temperature during MW irradiation up to ∼680 °C. This highlights the GAC strong ability to transform MW power into heat due to GAC excellent dielectric properties (ε′ = 13.8). Physical characterization revealed that GAC pore volume and specific surface area change with the number of regeneration cycles. GAC regeneration efficiency variation reflects this behaviour with a maximum value of ∼112% (5th cycle). The final GAC weight loss of ∼7% further demonstrates GAC life span preservation during MW irradiation.Results from column tests confirms that GAC can be regenerated by MW also in dynamic condition, due to sublimation/vaporization and vapour stripping Cs removal mechanisms and that the regeneration effectiveness is time-dependent. The breakthrough curve shape confirms significant benefits from MW irradiation. Overall, obtained finding demonstrated the feasibility of the proposed concept, also providing essential data to guide its scaling-up application.

Influence of Air Cooling on the Fatigue of a Polymer Composite Under Self-Heating

The self-heating effect occurs during cyclic loadings or vibrations of composite elements, which may significantly intensify their structural degradation due to a rapid temperature increase. For minimizing this influence, the air cooling can be used. In this study, the influence of air cooling on the fatigue and residual life of a cyclically loaded structure was investigated by analyzing the self-heating temperature history and using acoustic emission. A phenomenological model of self-heating of a composite structure during air cooling is presented and discussed, with identification of possible scenarios of self-heating temperature evolution. The theoretical studies were verified experimentally, and results showed that, by removing the heat generated, the durability of a structure undergoing self-heating can be increased significantly.

Experimental and modeling analysis of thermal characteristics in carbon fiber wires

AbstractTo understand the thermal characteristics of carbon fiber heating wires, we tested the heating rules of carbon fiber heating wires with inner core tows of 12k and 24k and different lengths. We found that the surface temperature of the carbon fiber heating wires rose and fell quickly when the power supply was turned on and off by 82.9 and 18.3°C/min, respectively. After the quick rise period, the surface temperature tended to be steady with ±2°C of fluctuation; the steady temperature decreased as the length increased. With an increase in the length from 7 to 12 m, the steady temperature of the 12k and 24k wires reduced from 122°C and 166°C to 53°C and 71°C, respectively. Using the COMSOL Multiphysics software to simulate the carbon fiber heating wires, the simulated surface temperatures were in good agreement with the experimental results, with errors less than 7%. The convective and radiative heat transfer of the simulated carbon fiber electric heating wire decreased with an increase in length and the number of tows, and the convective heat transfer was much higher than the radiative heat transfer to indicate that the convective heat transfer is the main heat transfer mode in the heat dissipation of the carbon fiber electric heating wire. Results indicate that there is a rapid increase in temperature when power is on, and thereafter temperature remains constant. These are the important characteristics of carbon fiber heating wires.

Morning Overshoot of Electron Temperature as Observed by the Swarm Constellation and the International Space Station

AbstractThe rapid increase of electron temperature in the early morning hours at low latitudes is a well‐known ionospheric phenomenon called morning overshoot. In this study, we extensively investigate the dependence of morning overshoot on local time, season, latitude/longitude/altitude, and magnetic activity. The electron temperature and density data set used in this study are obtained from (1) the Swarm constellation at two different altitudes of 470 and 520 km with identical payloads and (2) the Floating Potential Measurement Unit onboard International Space Station at an altitude of 400 km. Based on the data between 2014 and 2019, the main findings of this study are as follows: (1) on a global average, morning overshoot generally weakens with decreasing altitudes. (2) Morning overshoot is stronger around the dip equator than at midlatitude regions. As latitude increases, the overshoot decreases gradually and shifts to later local times. (3) In off‐equatorial regions the overshoot is stronger in the winter than in the summer hemisphere, especially at higher altitudes. (4) Lastly, the morning overshoot shows multiday oscillations, which are negatively correlated with plasma density and affected by geomagnetic activity.

Microstructural and mechanical assessment of the causes of failure of floors made of polyurethane-cement composites

The article presents the results of microstructural and mechanical testing of a floor made of polyurethane-cement composite significantly damaged after short-term use. The floor is located in a large-scale production and warehouse building. There was a lot of damage, including local abrasions, roughness, burns, and burning of the floor, which all threaten the safety of its use. Based on the carried out tests, errors in the execution of the tested floor were excluded and it was shown that the technology of its execution was correct. It was demonstrated, on the basis of research, that the reason that led to the damage was the improper use of the floor. This improper use consisted of allowing forklift drive wheels to spin pallets in order to deliver them with goods when adding or picking pallets to or from the pallet stack. The consequence of spinning was the rapid local increase in floor temperature, which caused a thermal shock to which the floor was not resistant.

Experimental investigation and hygrothermal modelling of freeze-thaw process of saturated fired clay materials including supercooling phenomenon

To investigate the supercooling phenomenon in fired clay materials, low-temperature differential scanning calorimetry (DSC) and a one-dimensional freeze-thaw (FT) experiment were performed on saturated specimens. The rate of increase in ice saturation during freezing was calculated from the DSC result. Rapid ice growth over a relatively narrow temperature range (within about 0.2 K) was observed at a cooling rate of 0.25 K/min. In the FT experiment, the temperature distribution of a specimen was measured with inserted thermocouples. According to the results of the FT experiment, a rapid temperature increase was observed at sub-zero temperatures accompanied by freezing of the supercooled water. When the supercooled water began to freeze, the released latent heat was found to strongly prevent the specimen temperature from dropping even during the cooling period. Finally, a hygrothermal model of freezing and thawing including a non-equilibrium supercooling process was developed. The freezing rate of the supercooled water was modelled based on the DSC result. The validity of the model was verified by comparing the results of the FT experiment and calculations. The model was found to be able to replicate the rapid temperature rise during the cooling period of the FT experiment.

Sustainable Bio-Conversion of Rice Straw Waste into High Quality Organic Fertilizer

The aim of this study is to investigate the effect of different additives including biochar, effective micro-organisms (EM), animal manure and commercial microbial inoculants on the bioconversion of rice straw. Different compost piles were constructed, and each contained 50 kg of rice straw and mixture of natural rocks to enrich the compost nutritional value. The physical, chemical and biological parameters indicating the decomposition of organic material, maturation and quality of the organic fertilizer product were investigated during the composting process. A rapid increase in compost temperature was obtained in inoculated piles. All piles reached maturation after around 42 days. All analysis of the properties of the final compost products indicated that it was in the range of the matured level and can be used as organic fertilizer without limitation. The highest decomposition rate and highest organic fertilizer quality were obtained in the pile inoculated with EM and 10% biochar compared to other treatments.

Resilience of Oxygen Consumption Rates in the Juvenile Blue Crab Callinectes sapidus to Future Predicted Increases in Environmental Temperature and pCo2 in the Mesohaline Chesapeake Bay

Quantifying the physiological impact of environmental stressors on living organisms is critical to predicting the response of any given species to future climate scenarios. Oxygen consumption rates (μmol/g/min) were measured to examine the physiological response of the juvenile blue crab Callinectes sapidus from the Chesapeake Bay (Patuxent River, Maryland) to elevated temperature and dissolved carbon dioxide in water (pCO2) reflective of projected future climate scenarios. Treatment levels were selected to represent current conditions in the Chesapeake Bay (26°C and 800 μatm) and conditions predicted to occur by the year 2100 (31°C and 8,000 μatm). Crabs were exposed in a factorial design to these conditions throughout two successive molts (approximately 30 days). At the end of the exposure, the oxygen consumption rates of individual crabs were determined over at least a 10-h period using a flow-through respiration chamber equipped with optical oxygen electrodes. No significant effect of temperature or pCO2 on oxygen consumption was observed, suggesting the absence of a respiratory impact of these two climate stressors on juvenile blue crabs. Oxygen consumption rates were also determined for crabs that experienced a rapid increase in temperature without prior acclimation. The oxygen consumption rate of crabs may have acclimated to increased temperature during the 30-day exposure period before respiratory measurement. This potential acclimation, combined with high individual variability, and a relatively small difference in temperature treatments are likely the cause for the lack of a statistically significant difference in mean oxygen consumption rates by temperature in the core experiment. The results of this study suggest that the blue crab may be quite resilient to future climate stressors and underscore the need for species-specific studies to quantify the effects of climate change on estuarine crustaceans.

Thermodynamic approach for determination of fuel relocation condition in severe accident progression

In a severe accident, a rapid temperature increase leads to thinning of the ZrO2 layer and the both of the UO2 dissolution by molten Zr, and relocation could take place within very short period. This paper considered such situation and proposed the relocation condition of “the quick dissolution scenario” with the melt composition at relocating temperature under a quasi-equilibrium assumption. The calculated values were compared with the UO2 solubility observed in the UO2–Zr dissolution tests representing “the slow dissolution scenario” in which the melt is held for a while by the ZrO2 layer. Two phases were recognized in the experiments with latter scenario: ceramic (U,Zr)O2−x phase and metallic liquid phase. The melt composition in each scenario was also converted from the U–Zr–O system to the UO2–ZrO2–Zr system as an example of user-defined criteria of dissolution which can be applied to the severe accident code analysis. The difference between two scenarios (“quick” and “slow”) can result in differing times of lower head failure through the high liquidus temperature of oxide solid phase or chemical activity of metallic liquid phase. Providing the conditions for different mechanisms in the consistent manner for the thermodynamic analysis enabled evaluation of the fuel dissolution behavior in the context of integral accident progression.

“Surface,” “satellite” or “simulation”: Mapping intra‐urban microclimate variability in a desert city

AbstractMapping spatial and temporal variability of urban microclimate is pivotal for an accurate estimation of the ever‐increasing exposure of urbanized humanity to global warming. This particularly concerns cities in arid/semi‐arid regions which cover two fifths of the global land area and are home to more than one third of the world's population. Focusing on the desert city of Be'er Sheva Israel, we investigate the spatial and temporal patterns of urban–rural and intra‐urban temperature variability by means of satellite observation, vehicular traverse measurement, and computer simulation. Our study reveals a well‐developed nocturnal canopy layer urban heat island in Be'er Sheva, particularly in the winter, but a weak diurnal cool island in the mid‐morning. Near surface air temperature exhibits weak urban–rural and intra‐urban differences during the daytime (&lt;1°C), despite pronounced urban surface cool islands observed in satellite images. This phenomenon, also recorded in some other desert cities, is explained by the rapid increase in surface skin temperature of exposed desert soils (in the absence of vegetation or moisture) after sunrise, while urban surfaces are heated more slowly. The study highlights differences among the three methods used for describing urban temperature variability, each of which may have different applications in fields such as urban planning, climate change mitigation, and epidemiological research.

High-Performance Plasma-Enabled Biorefining of Microalgae to Value-Added Products.

Conversion of renewable biomass by time- and energy-efficient techniques remains an important challenge. Herein, plasma catalytic liquefaction (PCL) is employed to achieve rapid liquefaction of microalgae under mild conditions. The choice of the catalyst affects both the liquefaction efficiency and the yield of products. The acid catalyst is more effective and gave a liquid yield of 73.95 wt % in 3 min, as opposed to 69.80 wt % obtained with the basic catalyst in 7 min. Analyses of the thus-formed products and the processing environment reveal that the enhanced PCL performance is linked to the rapid increase in temperature under the effect of plasma-induced electric fields and the generation of large quantities of reactive species. Moreover, the obtained solid residue can be simply upgraded to a carbon product suitable for supercapacitor applications. Therefore, the proposed strategy may provide a new avenue for fast and comprehensive utilization of biomass under benign conditions.

Near-infrared light and glucose dual-responsive cascading hydroxyl radical generation for in situ gelation and effective breast cancer treatment

A general therapeutic strategy to treat breast cancer is attractive as different subtypes of breast cancers often exhibit distinct response to existing cancer therapeutics. To this end, we prepare a catalyst couple of glucose oxidase (GOx) and gallic acid-ferrous (GA-Fe) nanocomplexes, a type of near-infrared (NIR) absorbing Fenton catalyst, to enable NIR-trigger in-situ gelation and enhanced chemodynamic/starvation therapy that appears to be effective for different types of breast cancer cells. In this system, GOx is mixed with GA-Fe in a solution of N,N-dimethylacrylamide (DMAA) and poly (ethylene glycol) double acrylate (PEGDA). Upon intratumoral injection and NIR laser exposure, such GA-Fe show rapid temperature increase, which would simultaneously increase the catalytic efficiencies of GA-Fe and GOx. The cascade production of hydroxyl radicals (•OH) from glucose is then initiated to enable polymerization of DMAA and PEGDA to form a hydrogel at the injection site within the tumor. The continuous production of cytotoxic •OH together with glucose depletion by the intratumorally fixed catalyst couple would further confer effective destruction of breast cancer tumors by such chemodynamic/starvation therapy. Our work presents a hydrogel-based therapeutic strategy for local treatment of solid tumors with high tumor destruction efficacy and low systemic toxicity.

Rapid, High-Temperature, In Situ Microwave Synthesis of Bulk Nanocatalysts.

Carbon-black-supported nanoparticles (CNPs) have attracted considerable attention for their intriguing catalytic properties and promising applications. The traditional liquid synthesis of CNPs commonly involves demanding operation conditions and complex pre- or post-treatments, which are time consuming and energy inefficient. Herein, a rapid, scalable, and universal strategy is reported to synthesize highly dispersed metal nanoparticles embedded in a carbon matrix via microwave irradiation of carbon black with preloaded precursors. By optimizing the amount of carbon black, the microwave absorption is dramatically improved while the thermal dissipation is effectively controlled, leading to a rapid temperature increase in carbon black, ramping to 1270 K in just 6 s. The whole synthesis process requires no capping agents or surfactants, nor tedious pre- or post-treatments of carbon black, showing tremendous potential for mass production. As a proof of concept, the synthesis of ultrafine Ru nanoparticles (≈2.57 nm) uniformly embedded in carbon black using this microwave heating technique is demonstrated, which displays remarkable electrocatalytic performance when used as the cathode in a Li-O2 battery. This microwave heating method can be extended to the synthesis of other nanoparticles, thereby providing a general methodology for the mass production of carbon-supported catalytic nanoparticles.