Microwave treatment has been considered as a promising rock breakage method. The weakening mechanism of vaporizing expansion of pore water in sandstone under microwave irradiation was studied in this ...paper. The effect of water in the heating process was studied by comparing the heating characteristics of dry and saturated sandstones, which was further explained by the mercury intrusion porosimetry tests. Moreover, the influencing factors including rock strength, permeability, saturation degree and microwave power on rock bursting were investigated by comparing the bursting time of water-bearing sandstone samples under microwave irradiation. The results show that water plays a more important role in the heating process of sandstones with higher porosity and lower microwave sensitivity. The heating curves of saturated sandstones can be divided into 3 stages according to the heating rate, which is related to the interaction of water heating and steam escape during microwave irradiation. In addition, it is found that the favorable conditions of water-bearing sandstone bursting under microwave irradiation are low rock strength, low permeability, high saturation degree and high microwave power. This law can be explained by the interaction of rock properties and the generation, increase, diffusion, and escape of steam in rock.
•The effect of pore water in the heating process of sandstone is analyzed.•The heating curves of saturated sandstones can be divided into 3 stages.•The weakening mechanism of vaporizing expansion is studied.•The favorable conditions of water-bearing sandstone bursting are derived.
Phase diagrams are "maps" materials scientists often use to design new materials. They define what compounds and solutions are formed and their respective compositions and amounts when several ...elements are mixed together under a certain temperature and pressure. This monograph is the most comprehensive reference book on experimental methods for phase diagram determination. It covers a wide range of methods that have been used to determine phase diagrams of metals, ceramics, slags, and hydrides.* Extensive discussion on methodologies of experimental measurements and data assessments * Written by experts around the world, covering both traditional and combinatorial methodologies * A must-read for experimental measurements of phase diagrams
Cancer stem cells (CSCs) are inherently resistant to chemotherapy, and CSCs in chemotherapy-failed recurrent tumors are enriched; however, the cellular origin of chemotherapy-induced CSC enrichment ...remains unclear. Communication with stromal fibroblasts may induce cancer cell dedifferentiation into CSCs through secreted factors. We recently demonstrated that fibroblast-derived exosomes promote chemoresistance in colorectal cancer (CRC). Here, we report that fibroblasts confer CRC chemoresistance via exosome-induced reprogramming (dedifferentiation) of bulk CRC cells to phenotypic and functional CSCs. At the molecular level, we provided evidence that the major reprogramming regulators in fibroblast-exosomes are Wnts. Exosomal Wnts were found to increase Wnt activity and drug resistance in differentiated CRC cells, and inhibiting Wnt release diminished this effect in vitro and in vivo. Together, our results indicate that exosomal Wnts derived from fibroblasts could induce the dedifferentiation of cancer cells to promote chemoresistance in CRC, and suggest that interfering with exosomal Wnt signaling may help to improve chemosensitivity and the therapeutic window.
To clone and characterize genes encoding novel cellulases from metagenomes of buffalo rumens. A ruminal metagenomic library was constructed and functionally screened for cellulase activities and 61 ...independent clones expressing cellulase activities were isolated. Subcloning and sequencing of 13 positive clones expressing endoglucanase and MUCase activities identified 14 cellulase genes. Two clones carried two gene clusters that may be involved in the degradation of polysaccharide nutrients. Thirteen recombinant cellulases were partially characterized. They showed diverse optimal pH from 4 to 7. Seven cellulases were most active under acidic conditions with optimal pH of 5·5 or lower. Furthermore, one novel cellulase gene, C67-1, was overexpressed in Escherichia coli, and the purified recombinant enzyme showed optimal activity at pH 4·5 and stability in a broad pH range from pH 3·5 to 10·5. Its enzyme activity was stimulated by dl-dithiothreitol. The cellulases cloned in this work may play important roles in the degradation of celluloses in the variable and low pH environment in buffalo rumen. This study provided evidence for the diversity and function of cellulases in the rumen. The cloned cellulases may at one point of time offer potential industrial applications.
A charge-density wave (CDW) state has a broken symmetry described by a complex order parameter with an amplitude and a phase. The conventional view, based on clean, weak-coupling systems, is that a ...finite amplitude and long-range phase coherence set in simultaneously at the CDW transition temperature T(cdw). Here we investigate, using photoemission, X-ray scattering and scanning tunnelling microscopy, the canonical CDW compound 2H-NbSe2 intercalated with Mn and Co, and show that the conventional view is untenable. We find that, either at high temperature or at large intercalation, CDW order becomes short-ranged with a well-defined amplitude, which has impacts on the electronic dispersion, giving rise to an energy gap. The phase transition at T(cdw) marks the onset of long-range order with global phase coherence, leading to sharp electronic excitations. Our observations emphasize the importance of phase fluctuations in strongly coupled CDW systems and provide insights into the significance of phase incoherence in 'pseudogap' states.
Microwave-assisted mechanical excavation has been considered as a promising rock breakage method and is widely studied in recent years. Heating characteristics of minerals are the basis of research ...on the weakening effect of microwave irradiation on rock. In this paper, 14 igneous rock-forming minerals were microwave heated. The influences of microwave power, mineral group/sub-group, element content and water on the heating characteristics of these minerals were analyzed. The results show that the microwave sensitivities of these minerals can be categorized into different levels according to their heating rates. As the microwave power increases, the microwave sensitivity of minerals remains unchanged. Mineral group has the greatest influence on their microwave sensitivities, followed by crystal structure and iron content. In addition, different kinds of water contained in minerals greatly influence their heating characteristics.
•14 igneous rock-forming minerals are heated under microwave irradiation.•The sensitivities of the minerals are classified according to the heating rate.•The influences of mineral group/sub-group and element content are analyzed.•The impacts of microwave power and water are studied.
Clouds cover about 70% of Earth's surface and play a dominant role in the energy and water cycle of our planet. Only satellite observations provide a continuous survey of the state of the atmosphere ...over the entire globe and across the wide range of spatial and temporal scales that compose weather and climate variability. Satellite cloud data records now exceed more than 25 years; however, climate data records must be compiled from different satellite datasets and can exhibit systematic biases. Questions therefore arise as to the accuracy and limitations of the various sensors and retrieval methods. The Global Energy and Water Cycle Experiment (GEWEX) Cloud Assessment, initiated in 2005 by the GEWEX Radiation Panel (GEWEX Data and Assessment Panel since 2011), provides the first coordinated intercomparison of publicly available, standard global cloud products (gridded monthly statistics) retrieved from measurements of multispectral imagers (some with multiangle view and polarization capabilities), IR sounders, and lidar. Cloud properties under study include cloud amount, cloud height (in terms of pressure, temperature, or altitude), cloud thermodynamic phase, and cloud radiative and bulk microphysical properties (optical depth or emissivity, effective particle radius, and water path). Differences in average cloud properties, especially in the amount of high-level clouds, are mostly explained by the inherent instrument measurement capability for detecting and/or identifying optically thin cirrus, especially when overlying low-level clouds. The study of long-term variations with these datasets requires consideration of many factors. The monthly gridded database presented here facilitates further assessments, climate studies, and the evaluation of climate models.
Understanding how flowering phenology responds to warming and cooling (i.e., symmetric or asymmetric response) is needed to predict the response of flowering phenology to future climate change that ...will happen with the occurrence of warm and cold years superimposed upon a long-term trend. A three-year reciprocal translocation experiment was performed along an elevation gradient from 3200 m to 3800 m in the Tibetan Plateau for six alpine plants. Transplanting to lower elevation (warming) advanced the first flowering date (FFD) and transplanting to higher elevation (cooling) had the opposite effect. The FFD of early spring flowering plants (ESF) was four times less sensitive to warming than to cooling (by −2.1 d/°C and 8.4 d/°C, respectively), while midsummer flowering plants (MSF) were about twice as sensitive to warming than to cooling (−8.0 d/°C and 4.9 d/°C, respectively). Compared with pooled warming and cooling data, warming alone significantly underpredicted 3.1 d/°C for ESF and overestimated 1.7 d/°C for MSF. These results suggest that future empirical and experimental studies should consider nonlinear temperature responses that can cause such warming-cooling asymmetries as well as differing life strategies (ESF vs. MSF) among plant species.
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