•Effective diffusion coefficient of various porous building materials is calculated.•For reconstruction of porous building materials a new RGMMP method is proposed.•Lattice Boltzmann method is ...adapted for mass diffusion through porous structures.•Special treatment of solid matrix and macro–meso pores is considered.•Obtained results are validated with experimental data (MIP).
Diffusion coefficient is an important parameter used to predict the volatile organic compounds (VOC’s) emission or sorption characteristics in porous building materials. Scale of the pores in building materials can be classified into macro and meso pores and the connection between them is very important to predict the diffusion coefficient. Many (theoretical and experimental) models have been proposed for the (macro–meso) pore connection. In contrast to these traditional models, a new numerical random generation macro–meso pores (RGMMP) method, based on geometrical and morphological information acquired from measurements or experimental calculations, is proposed here. This method not only reflects the stochastic macro–meso pores distribution characteristics of porous building materials but also can be used to calculate the mass (VOC) diffusion through building materials of very low porosity. The division of macro and meso pores’ diameter and porosities is based on average pore diameter, mean free path and total porosity of the material. Lattice Boltzmann method along with the proposed structure generating tool RGMMP is validated with some theoretical values and then is applied for modeling and prediction of effective diffusion coefficient of wide range of porous building materials. The predicted effective diffusion coefficients are in good agreement with available experimental data.
The grafting of Ga(iBu)3 on a series of meso-H-ZSM5, prepared by desilication-dealumination (Si/Al = 25, 50, 100, 200, ∞), has been studied. Materials were characterized by IR, solid-state NMR, BET, ...ICP and EXAFS. Ga(iBu)3 reacts selectively with silanol groups, yielding a monopodal surface species in the mesopores. Importantly, the Brønsted acidic sites remain intact in the micropores, as revealed by IR and 1H MAS-NMR. These materials can be regarded as bifunctional catalysts, containing isolated Ga sites and Brønsted sites in proximity, suitable for propane aromatization. Catalytic investigations show high activity and selectivity toward aromatics, particularly for low Si/Al ratios.
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•A series of meso-H-ZSM-5 (Si/Al = 25 - ∞) has been synthesized by post treatment and characterized.•GaiBu3/meso-H-ZSM-5 catalysts were synthesized via Surface Organometallic Chemistry from GaiBu3 precursor.•A series of catalyst GaiBu2/meso-H-ZSM-5 with different Bronsted acidity have been synthesized and characterized.•The bifunctional catalysts (GaiBu2/meso-H-ZSM-5) are active and selective in propane aromatization•The ideal Si/Al ratio appears to be at 50 with respect to the activity and selectivity in aromatics (BTX)
Elevated level of hypochlorous acid (HClO) is closely associated with cancer development. Identifying HClO level in cancer cells would provide important evidence in either early-stage cancer ...diagnostics or monitoring of its treatment efficiency. In this work, a new pyronine-based fluorescent probe for rapid and sensitive detection of HClO was developed by condensing meso‑formyl pyronine (PyCHO) with 2-hydrazinopyridine to form meso‑pyridylhydrazone-functionalized pyronine PyHP, PyHP is nonfluorescent due to the excited-state C=N isomerization nonradiative decay, whereas the HClO-triggered formation of meso‑triazolopyridyl pyronine PyTP abolishes the C=N isomerization and thus greatly enhances the fluorescence. With the probe, the cancer cells/tumor were distinguished with high-contrast from normal ones by laser confocal fluorescence imaging, and the tumor-to-normal (T/N) ratios obtained exceed the clinically acceptable threshold of 2.0. Moreover, its capability of in vivo imaging tumor was also demonstrated. These results indicate the potential of PyHP as an effective tool in the early clinical diagnosis of cancers.
A new pyronine-based fluorescent probe for rapid and sensitive detection of hypochlorous acid (HClO) was developed by condensing meso‑formyl pyronine (PyCHO) with 2-hydrazinopyridine to form meso‑pyridylhydrazone-functionalized pyronine PyHP. With the probe, the cancer cells/tumor were distinguished with high-contrast from normal ones by laser confocal fluorescence imaging, and the tumor-to-normal (T/N) ratios obtained exceed the clinically acceptable threshold of 2.0; moreover, its capability of in vivo imaging tumor was also demonstrated.
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Conventional electrodes are of significant challenges in acquiring bioelectric signals concerning a high signal‐to‐noise ratio (SNR), long‐term and comfortable wear, low motional noise, etc. To ...resolve these issues, silk fibroin (SF) materials are adopted to create flexible microneedle array electrodes (FMNA‐electrode) based on meso‐engineering. The research approaches involve constructing flexible conductive electrodes from non‐conductive and bristle‐regenerated SF. By controlling the molecular interchain nucleation in the refolding process of unfolded regenerated SF molecules, this goal can be achieved. In this process, silver nanowires (Ag NWs) are adopted as meso‐dopants to reconstruct the meso‐electronic structure of SF films at the surface, while polyurethane (PU) is selected as molecular templates to facilitate the molecular nucleation in the refolding of SF molecules. This leads to the occurrence of SF‐PU meso‐hybridization, giving rise to more flexible meso‐hybridized SF. The SF‐PU FMNA‐electrode demonstrates biocompatibility, comfort wearing, long‐term monitoring capability, low motional noise, and a high SNR in the application of collecting ECG, EMG, and EOG signals. The outperformance of SF‐PU FMNA‐electrode is superior to both conventional wet and commercially available dry electrodes, paving the way for the next generation of flexible, skin‐friendly, durable, and high‐performance health monitoring devices and brain‐machine interfaces.
Biocompatible, flexible microneedle array electrodes (FMNA‐electrodes) are developed based on non‐conductive silk fibroin (SF) from meso‐engineering. It follows that apart from the inherent advantage of biocompatibility, the SF‐PU FMNA‐electrodes demonstrate remarkable overall performance in terms of high sensitivity, low motional noise, a high signal‐to‐noise ratio (SNR), etc. These will have relevant biomedical implications and an important impact on the brain‐machine interface.
Here we report the preparation of first examples of iridium‐based organometallic macromolecules, viz., iridium‐tetra (4‐carboxyphenyl)porphyrin (IrTCPP), iridium‐calix4pyrrole (IrCP) ...iridium‐tetraphenylporphyrin (IrTPP), which are effective catalysts for hydrogenation of levulinic acid (LA) to γ‐valerolactone (GVL) and 1,4‐pentanediol under base free conditions. The turnover number in the range of 1220–2850 is evident for the chosen reaction using iridium macromolecule based catalysts. The heterogenization of homogeneous IrTCPP, IrCP, and IrTPP result in stable reactivity of the catalysts for several runs.
The novel class of iridium‐based organometallic macromolecules, viz., iridium‐tetra (4‐carboxyphenyl)porphyrin (IrTCPP), iridium‐calix4pyrrole (IrCP), iridium‐tetraphenylporphyrin (IrTPP) were prepared and heterogenized on functional mesoporus materials. Both homogeneous and heterogeneous catalysts effecitively convert levulinic acid to γ‐valerolactone and 1,4‐pentane‐diol under H2 atmosphere.
ABSTRACT
Knowledge of the rifting and opening process of the Meso‐Tethys Ocean is important for understanding the evolution of the Tethys tectonic domain and for an in‐depth understanding of Tethys ...dynamics. Sedimentary rocks are faithful recorders of surface expressions of tectonic events and are thus expected to have recorded the rifting and opening of the Meso‐Tethys Ocean. This study presents petrography, sedimentology, zircon U–Pb geochronological data and Hf isotope data for the Carboniferous–Permian Shiquanhe stratigraphic succession in the Lhasa Terrane of the Tibetan Plateau. The data indicate that the 300 to 273 Ma Lagar and Angjie formations in the lower section of the Carboniferous–Permian Shiquanhe succession were deposited in the stable passive margin of northern Gondwana with sediment sources in Gondwanaland. However, the 273 to 252 Ma Xiala Formation in the upper section of the Carboniferous–Permian Shiquanhe succession was deposited in a tectonically active setting characterized by intense magmatic activity. Considering the transition from the Lagar and Angjie formations to the Xiala Formation, a significant change in depositional setting from tectonically stable to tectonically active occurred at ca 273 Ma. Similar Early–Middle Permian changes in depositional setting have also been identified in the South Qiangtang, Baoshan and Oman regions in the Tethyan tectonic domain. These widespread changes in depositional setting, together with Early–Middle Permian tectonic uplift and episodes of subsidence, as well as rift‐related magmatism in the South Qiangtang, Baoshan, Himalayan, Zagros, Oman and Turkey regions once located in northern Gondwana, constitute a complete record of continental rifting–ocean opening associated with the diachronous opening of the Meso‐Tethys Ocean during the Early–Middle Permian.
The precision fabrication of ceramic moulds for the mass-production of micro/meso-structural arrays places a tremendous challenge to the manufacturing industry. This work aims to reveal the physics ...behind the processes so as to address this technological challenge. A new method for texturing the diamond grinding wheel surface with a micro-abrasive waterjet is proposed for highly efficient form-grinding of ceramic moulds into the required micro/meso-structural surfaces. It shows that this technology provides some unique advantages in improving the sharpness and geometrical accuracy of the grinding wheels. The mechanisms about material removal and texture formation in grinding wheel truing are investigated to enable the precise control of micro/meso-structure generation on the grinding wheel. A theoretical model is established to study the effect of grinding wheel surface micro/meso-textures and grain trajectory on the quality of the ground mould surface and reveal the reflection mechanism of the ground marks on the mould surface. Furthermore, an integrated rough-fine grinding strategy is proposed which is shown to significantly increase the grinding efficiency by 15–24 times. It is found that ductile domain grinding of ceramic moulds to achieve the required contour profile of 6.7 μm PV accuracy and a surface roughness Ra of less than 40 nm can be achieved.
Titanium implants are the standard therapeutic option when restoring missing teeth and reconstructing fractured and/or diseased bone. However, in the 30 years since the advent of micro-rough ...surfaces, titanium's ability to integrate with bone has not improved significantly. We developed a method to create a unique titanium surface with distinct roughness features at meso-, micro-, and nano-scales. We sought to determine the biological ability of the surface and optimize it for better osseointegration. Commercially pure titanium was acid-etched with sulfuric acid at different temperatures (120, 130, 140, and 150 °C). Although only the typical micro-scale compartmental structure was formed during acid-etching at 120 and 130 °C, meso-scale spikes (20-50 μm wide) and nano-scale polymorphic structures as well as micro-scale compartmental structures formed exclusively at 140 and 150 °C. The average surface roughness (Ra) of the three-scale rough surface was 6-12 times greater than that with micro-roughness only, and did not compromise the initial attachment and spreading of osteoblasts despite its considerably increased surface roughness. The new surface promoted osteoblast differentiation and in vivo osseointegration significantly; regression analysis between osteoconductivity and surface variables revealed these effects were highly correlated with the size and density of meso-scale spikes. The overall strength of osseointegration was the greatest when the acid-etching was performed at 140 °C. Thus, we demonstrated that our meso-, micro-, and nano-scale rough titanium surface generates substantially increased osteoconductive and osseointegrative ability over the well-established micro-rough titanium surface. This novel surface is expected to be utilized in dental and various types of orthopedic surgical implants, as well as titanium-based bone engineering scaffolds.
Simple scaling analysis of terms in the Navier‐Stokes momentum equation for Earth's atmosphere suggests that winds at heights above 120 km should be smooth and laminar, with little spatial variation ...over horizontal scale lengths smaller than several hundred kilometers. However, there is increasing evidence that this traditional understanding may fail to account for several important processes, including both waves and small‐scale ion‐neutral momentum coupling. Here, we examine the thermospheric neutral wind field over Alaska in unprecedented detail using observations from an array of four ground‐based all‐sky imaging Fabry‐Perot interferometers, processed using a new geophysical inverse algorithm, to derive high‐resolution maps of all three wind components, with a temporal cadence of 30 seconds. The reconstructed high‐resolution neutral winds showed synoptic‐scale agreement with prior observations and previously validated techniques, with all results exhibiting behavior in agreement with basic physics. However, stacked time‐series plots of vector wind components reveal significantly more spatial and temporal structure than previously reported. In particular, the observed responses included complex wave‐like behavior and highly geographically variable vertical winds. Local flow features were observed at spatial scales as small as 100 km at times, with temporal scales as short as a few tens of minutes. Instances of close spatial and temporal correlations were observed between the wind fields reconstructed from green‐line spectra and ionospheric flows observed independently by SuperDARN.
Key Points
Arrays of all‐sky viewing instruments obtain densely sampled Doppler remote sensing of thermospheric winds
Geophysical inverse techniques are well suited for providing near‐optimal spatially resolved reconstructions of thermospheric winds
Mesoscale structures are directly observed in the thermosphere with length scales as low as 100 km
Three-dimensional porous scaffolds doped with the heteroatoms show excellent performances in energy conversion and storage. Herein, we report a green synthesis approach to construct the oxygen-doped ...porous carbon electrodes by carbonizing the oxygen-rich biomass material, sodium alginate. By precisely controlling the carbonization temperature and increasing the mole ratio of α-L-guluronic acid units/β-D-mannuronic acid units in sodium alginate, the morphology, oxygen content and electrical conductivity of the as-obtained carbonaceous electrode are well balanced. This electrode material delivers capacitance of up to 424.6 F g−1 in 6 M potassium hydroxide (KOH) electrolyte at 1 A g−1, and good cyclic stability with the capacitance retention of >90% after 20,000 charge-discharge cycles. Such excellent electrochemical performance can be attributed to both the unique hierarchical macro-/meso-/microporous structure and the presence of abundant oxygen-containing functional groups in the as-prepared carbonized sodium alginate aerogels. The capacitance of our oxygen-doped porous carbon electrodes is at least twice greater than those of other carbonaceous electrodes produced from biomass precursors reported in literatures. This work provides a facile, effective and environmental-friendly approach for the fabrication of high-performance heteroatom-doped carbon-based electrodes for supercapacitor applications.
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•Oxygen-doped porous carbon was derived from cost-effective biomass material, sodium alginate.•The carbonized aerogel shows 3D interconnected structure with large surface area.•Carbonization temperature and G/M ratio are controlled to adjust the electrochemical properties.•The obtained carbon shows excellent specific capacitance (426.6F/g at 1A/g) and cycling stability.•The results pave a road for the future implication in cost-effective and eco-friendly energy storage devices.
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