Numerous natural systems contain surfaces or threads that enable directional water transport. This behaviour is usually ascribed to hierarchical structural features at the microscale and nanoscale, ...with gradients in surface energy and gradients in Laplace pressure thought to be the main driving forces. Here we study the prey-trapping pitcher organs of the carnivorous plant Nepenthes alata. We find that continuous, directional water transport occurs on the surface of the 'peristome'--the rim of the pitcher--because of its multiscale structure, which optimizes and enhances capillary rise in the transport direction, and prevents backflow by pinning in place any water front that is moving in the reverse direction. This results not only in unidirectional flow despite the absence of any surface-energy gradient, but also in a transport speed that is much higher than previously thought. We anticipate that the basic 'design' principles underlying this behaviour could be used to develop artificial fluid-transport systems with practical applications.
•Concepts of critical states and safety regime are demonstrated for Li-ion battery.•Key kinetic features and dominant parameters of thermal runaway are identified.•Effects of electrode material ...properties on thermal runaway are evaluated.•Heat release distribution and evolution is shown for typical internal short circuit.•A combined model of thermal-electrochemical and thermal runaway is demonstrated.
Internal short circuit (ISC) and the subsequent electrochemical heat release is frequently a direct cause to trigger Li-ion battery thermal runaway. In this work, a decouple-recombine modeling approach is adopted to reveal the feature of thermal runaway induced by a typical ISC event. The thermal response and chemical kinetic feature of thermal runaway is computationally investigated in a three-dimensional configuration with assigned heat source intensity and duration. The threshold runaway state and the safety regime diagram are identified, corresponding to a pair of critical heat source intensity and critical duration time. Consequently, a safety regime diagram is computationally identified to distinguish the thermal runaway zone and safety zone. Simulation and analysis has been conducted to evaluate the dominant physical-chemical parameters, and the dependence of cathode material during thermal runaway. Meanwhile, the power dissipation during a representative ISC scenario is analyzed, where the local current could be an order of magnitude higher than that for a regular 1C discharge, and the maximum heat release rate is around 1012 W/m3. This heat release is input as source in the thermal runaway simulation, to demonstrate the coupling of the ISC and thermal abuse models. This work provides useful guidance to the fundamental understanding and prediction of thermal runaway phenomena induced by internal short circuit in Li-ion batteries.
Photothermal therapy (PTT) is an emerging treatment modality that is under intensive preclinical investigations for the treatment of various medical conditions, including cancer. However, the lack of ...targeting function of PTT agents hampers its clinical application. An effective and nontoxic delivery vehicle that can carry PTT agents into tumor areas is still needed urgently. In this study, we developed a multifunctional nanocomposite by loading copper sulfide (CuS) into Cy5.5-conjugated hyaluronic acid nanoparticles (HANP), obtaining an activatable Cy5.5–HANP/CuS (HANPC) nanocomposite. In this system, Cy5.5 fluorescent signal is quenched by CuS inside the particle until the whole nanocomposite is degraded by hyaluronidase present in tumor, giving strong fluorescence signals delineating the tumor. Importantly, CuS with strong NIR absorbance appears to be an excellent contrast agent for photoacoustic (PA) imaging and an effective PTT agent. After intravenous administration of HANPC into SCC7 tumor-bearing mice, high fluorescence and PA signals were observed in the tumor area over time, which peaked at the 6 h time point (tumor-to-normal tissue ratio of 3.25 ± 0.25 for optical imaging and 3.8 ± 0.42 for PA imaging). The tumors were then irradiated with a laser, and a good tumor inhibition rate (89.74% on day 5) was observed. Our studies further encourage application of this HA-based multifunctional nanocomposite for image-guided PTT in biomedical applications, especially in cancer theranostics.
The emerging interface solar-thermal water evaporation has been widely studied to solve fresh water shortage because of its high solar-thermal conversion efficiency, environmental friendliness, and ...low cost. However, traditional water evaporation systems inevitably lose heat to the environment, which not only greatly affects the water evaporation rate but also hinders their practical applications. In this work, an interface solar-thermal water evaporation system with enhanced heat localization, which is combined by a hydrophobic carbon nanotube (CNT) film (heating layer) and hydrophilic polyvinyl alcohol (PVA)/CNT foam (evaporating layer), is demonstrated. Under solar irradiation, the temperature of the hydrophobic CNT film is higher than that of the hydrophilic PVA/CNT foam due to the differences in wettability, so the thermal energy in the CNT film can be continuously transferred to the PVA/CNT foam evaporator, forming a gradient heating effect and greatly increasing the water evaporation rate. As a result, the water evaporation rate can reach 4.2 kg m–2 h–1 under a solar illumination of 1 kW m–2, which is among the highest water evaporation rate levels. More importantly, this water evaporation system structure is simple, can be easily scaled up, and has gradient applicability to other photothermal materials, which provides a route to improve the interfacial solar steam evaporation rate.
It is critical for designing shallow geothermal systems to accurately estimate thermal properties of soil and backfilling material. This paper reports on a new algorithm for simultaneously estimating ...thermal conductivities and diffusivities of soil and backfilling material. The algorithm uses a 2D composite-medium line-source solution for borehole ground heat exchangers, enabling early-time (<10 hr) data of thermal response tests (TRTs) to be used in the parameter estimation. The new algorithm is validated by a reference sandbox experimental data. Several theoretical issues of parameter estimation were explored, including sensitivity, identifiability, and uncertainty. The key findings of this study are: (1) the early-time data of TRTs can greatly reduce the linear dependence of the estimated parameters and thus improve the identifiability of the parameter estimation. (2) The accuracy of the estimates, ranked in descending order are as follows: soil thermal conductivity ks (±2%), grout thermal diffusivity ab and conductivity kb (±15%), soil thermal diffusivity as (±60%). (3) ±10% uncertainties in borehole radius, heating rate, and half-spacing of U-tube legs lead to the total deviations from the original estimates of ks, as, kb, or ab equal to 8.4%, 87.5%, 12.8%, and 15.5%, respectively.
•New estimation method is created and validated for interpreting TRT data.•The new algorithm uses a composite-medium line-source solution.•Conductivities and diffusivities of soil and grout are determined simultaneously.•Early-time (<10 h) data of TRTs can improve the identifiability of estimations.
Soft tissue damage is often at risk during the use of a surgical grasper, because of the strong holding force required to prevent slipping of the soft tissue in wet surgical environments. Improvement ...of wet friction properties at the interface between the surgical grasper and soft tissue can greatly reduce the holding force required and, thus, the soft tissue damage. To design and fabricate a biomimetic microscale surface with strong wet friction, the wet attachment mechanism of tree frog toe pads was investigated by observing their epithelial cell structure and the directionally dependent friction on their toe pads. Using these observations as inspiration, novel surface micropatterns were proposed for the surface of surgical graspers. The wet friction of biomimetic surfaces with various types of polygon pillar patterns involving quadrangular pillars, triangular pillars, rhomboid pillars, and varied hexagonal pillars were tested. The hexagonal pillar pattern exhibited improved wet frictional performance over the modern surgical grasper jaw pattern, which has conventional macroscale teeth. Moreover, the deformation of soft tissue in the bioinspired surgical grasper with a hexagonal pillar pattern is decreased, compared with the conventional surgical grasper.
A novel unidirectional liquid spreading surface with an inclined arc pitted groove, inspired by the continuous unidirectional liquid spreading mechanism on the peristome surface of N. alata, is ...explored and fabricated by two‐step UV lithography. Its superior unidirectional liquid spreading capability to that of other surface patterns is demonstrated, and its unidirectional liquid spreading mechanism is investigated.
•A novel nano materials Sr-doped β-Bi2O3 (Sr-Bi2O3) is successfully prepared.•The degradation of TC follows the pseudo-first-order kinetics by Sr-Bi2O3.•It is an effective and eco-friendly method to ...eliminate TC by Sr-Bi2O3.•A photochemical degradation mechanism of TC is proposed.•The intermediates formed by Sr-Bi2O3 photocatalysis have lower toxicity.
Photodegradation of tetracycline (TC) was investigated in aqueous solution by visible-light-driven photocatalyst Sr-doped β-Bi2O3 (Sr-Bi2O3) prepared via solvothermal synthesis. The decomposition of TC by Sr-Bi2O3 under visible light (λ>420nm) irradiation followed pseudo-first-order kinetics, and the removal ratio reached 91.2% after 120min of irradiation. Sr-Bi2O3 photocatalysis is able to break the naphthol ring of TC which decomposes to m-cresol via dislodging hydroxyl group step by step by photogenerated electron. This mechanism was verified by electron spin resonance measurement, the addition of radical scavengers and the intermediate product analysis, indicating that the photogenerated electron acts as a reductant and can be the key to the degradation process. In contrast, in TiO2 photocatalysis the naphthol ring is broken via oxidation by hydroxyl radical, while in direct photolysis the ring remains intact. In addition, the toxicity of photodegradation products was analyzed by bioluminescence inhibition. After 120min of irradiation by Sr-Bi2O3, the toxicity decreases by 90.6%, which is more substantial than direct photolysis (70%) and TiO2 photocatalysis (80%), indicating that the Sr-Bi2O3 photocatalysis is more eco-friendly than the other two methods.
In this study, porphyrinic zirconium (Zr) MOFs were investigated as heterogeneous photocatalysts for photoinduced electron transfer‐reversible addition‐fragmentation chain transfer (PET‐RAFT) ...polymerization of various monomers under a broad range of wavelengths, producing polymers with high monomer conversions, narrow molecular weight distributions, low dispersity and good chain‐end fidelity. Screening of various porphyrinic Zr‐MOFs (Zn) containing Zn‐metalled porphyrinic ligands demonstrated that MOF‐525 (Zn) with the smallest size had the best photocatalytic activity in PET‐RAFT polymerization, due to enhanced dispersion and light penetration. Oxygen tolerance and temporal control were also demonstrated during MOF catalysed PET‐RAFT. Results suggested that the polymerization rates were significantly affected by changing the size and surface area of MOFs, and the heterogeneous MOF photocatalysts could be easily separated and recycled for up to five independent PET‐RAFT polymerizations without an obvious decrease in efficiency. Finally, the MOF photocatalysts were utilized to create three‐dimensional polymeric objects with high resolution via visible light mediated stereolithography in an open‐air environment.
Porphyrinic zirconium MOFs act as heterogeneous photocatalysts for photoinduced electron transfer‐reversible addition‐fragmentation chain transfer (PET‐RAFT) polymerization of various monomers under a broad range of wavelengths, producing polymers with high monomer conversions, narrow molecular weight distributions, low dispersity and good chain‐end fidelity
The dynamic recrystallization (DRX) behavior of a medium carbon Cr-Ni-Mo alloyed steel 34CrNiMo was studied in the wide temperature range of 900–1150°C and the strain rate of 0.002–5s−1. Based on ...relations between the strain hardening rate and stress, the characteristic points, including critical strain (εc), critical stress (σc), peak strain (εp), peak stress (σp), were determined from the strain rate hardening versus stress curves. The Avrami equation was developed to model the kinetics of DRX, whereas the characteristic points can be expressed as a function of Zener-Hollomon parameter. Then the austenite grain size of DRX was measured by metallography and found to be a power law function of Zener-Hollomon parameter with an exponent of −0.2013. Besides, a mesoscopic cellular automaton model has been established to simulate the austenite DRX for the tested steel. This model was verified by means of the kinetics and topology of DRX.
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