[en] A k-ε-k_κ model for turbulent two-phase flows based on a particle turbulent kinetic energy equation is proposed. The predictions of a confined plane particle-laden jet show good agreement with the experimental data. The proposed model is proved to be far superior to the k-ε-A.P. model based on the algebraic of particle turbulence. (orig.)

[en] Aiming to reduce the weight under its rigidity and strength restrictions of a propeller processing machine tool, structural design optimization of the top beam of the machine tool is carried out using FEA analysis approach. Based on static and modal analysis, both the thickness and the width of the rib are optimized and light-weighted, followed FEA analysis results demonstrate that although the maximum stress and deformation of the optimized structure go up slightly, but are still allowable. After optimization, the weight of the top beam is reduced by approximately 8.03% and the dynamic characteristics of the top beam are also enhanced, which is beneficial to the noise reduction of the machine tool. (paper)

[en] Objective: To observe the changes of serum NO/NOS concentrations in rats after whole abdominal irradiation and their relationships with intestinal radiation injury. Methods: Thirty health rats were randomly divided into three groups: normal control group, irradiation control group, and IgY protection group. The sera of rats were collected and the NO and iNOS were assayed. Results: NO and iNOS levels increased evidently in the irradiation control group in contrast with those of the normal control group (P<0.01). NO and iNOS levels increased slightly in the IgY protection group in contrast with the irradiation control group (P<0.01) and were close to the levels of the normal control group. The changes of NO and NOS concentrations were synchronous. Conclusion: NO and iNOS are good indices for detecting intestinal radiation injury. (authors)

[en] Highlights: • A spool-like Ru-Ni nanocrystal (NC) with Ru distributed in the hexagonal ring and Ni concentrated in the pillar was successfully created. • The Ru-Ni NC exhibits enhanced performance toward both hydrogen evolution reaction and oxygen evolution reaction. • The optimized Ru-Ni SNs deliver a low onset potential of only 1.45 V and enhanced durability in the overall water splitting device. Since the interface in catalyst directly influences the catalytic performance, it is imperative to create hierarchical nanostructures with modulated atomic arrangements at the interfaces for catalysis optimization. Herein, we report an unprecedented ruthenium-nickel (Ru-Ni) heterostructure with phase-segregated sandwich-like morphology for boosting electrocatalysis. The Ru selectively grows at the two ends of the Ni pillar, in which intimate interfaces is formed between Ru and Ni domains. We found such Ru-Ni sandwiched nanoplates (SNs) are highly efficient for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline electrolytes with very low overpotentials and Tafel slopes. Significantly, the optimized Ru-Ni SNs deliver a low onset potential of only 1.45 V and enhanced durability in the overall water splitting device, indicating a promising electrocatalyst towards the practical alkaline electrolysis.

[en] Highlights: • The algorithm of constrained multi-objective MPC for RCCUV system was proposed. • Constrained multi-objective MPC controller of RCCUV system was developed. • MPC performance of RCCUV system was compared with that of PID by experiments. Radiant ceiling cooling integrated with underfloor ventilation (RCCUV) system has energy-saving potential in buildings. However, control problem results in its energy-saving effect lower than expected and restricts its application. Conventional control is inadequate due to its poor performance, control lag and low economy, etc. The objectives of this study are to: (1) develop advanced model predictive control (MPC) controller of RCCUV system; and (2) experimentally discuss MPC controller performance compared with conventional proportional-integral-derivative (PID) controller performance. The experimental results indicated that under experimental step setpoint variations, the adjusting time of controlled variables using MPC controller was less than that of using PID controller. The time to reach recommended thermal comfort range using MPC controller was 3 min, and was 13 min using PID controller under experimental step setpoint variations. Meanwhile, MPC controller reduced energy consumption of RCCUV system by 13.2% compared with PID controller during 2 h of experimental period. Thus, control performance of MPC controller is superior to that of PID controller in every aspect. The study provides an advanced superior MPC controller for RCCUV system.

[en] Highlights: • For the first time, a new class of all-inorganic SrSnO₃ perovskite nanowires are constructed and utilized to catalyze the CO₂ER. • The optimized SrSnO₃ nanowires show impressive selectivity and activity for formate production, much better than that of the SnO₂ nanoparticles. • Further analysis reveals the efficient stabilization for formate intermediate (CO₂.^{• −}) and slow HER kinetics of the SrSnO₃ nanowires. -- Abstract: Perovskite oxides are a class of attractive materials for their broad applications in many energy conversion and storage fields, while their catalytic performance of CO₂ electroreduction (CO₂ER) has been rarely investigated. Herein, all-inorganic SrSnO₃ perovskite nanowires are constructed and utilized to catalyze the CO₂ER for the first time. Inspiringly, such SrSnO₃ NWs demonstrates impressive selectivity and activity for formate production, with considerable Faradaic efficiencies (~80%) over a broad potential range, and the highest formate partial current density of 21.6 mA cm⁻², much better than that of the SnO₂ nanoparticles. Further analyses reveal that the notable CO₂ER activity of SrSnO₃ NWs is linked to the efficient stabilization of formate intermediate (CO₂^{• −}) as well as the slow kinetics for hydrogen evolution reaction (HER). This work can inspire the development of highly efficient perovskite catalysts for CO₂ER and beyond.

[en] Tuning surface electron transfer process by oxygen (O)-vacancy engineering is an efficient strategy to develop enhanced catalysts for CO${}_2$ electroreduction (CO${}_2$ER). Herein, a series of distinct InO${}_x$ NRs with different numbers of O-vacancies, namely, pristine (P-InO${}_x$), low vacancy (O-InO${}_x$) and high-vacancy (H-InO${}_x$) NRs, have been prepared by simple thermal treatments. The H-InO${}_x$ NRs show enhanced performance with a best formic acid (HCOOH) selectivity of up to 91.7 % as well as high HCOOH partial current density over a wide range of potentials, largely outperforming those of the P-InO${}_x$ and O-InO${}_x$ NRs. The H-InO${}_x$ NRs are more durable and have a limited activity decay after continuous operating for more than 20 h. The improved performance is attributable to the abundant O-vacancies in the amorphous H-InO${}_x$ NRs, which optimizes CO${}_2$ adsorption/activation and facilitates electron transfer for efficient CO${}_2$ER. (© 2019 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

[en] Highlights: • A dynamic simplified RC-network model of RFCUV system was created and validated. • Constrained multi-objective MPC controller of RFCUV system was developed. • MPC performance of RFCUV system was demonstrated by comparing with PID experimentally. -- Abstract: Energy saving potential of radiant floor cooling combined with underfloor ventilation (RFCUV) system has been restricted by its control problems. Existing conventional control methods of radiant cooling system have several disadvantages, such as control lag, poor control performance, and low economy, etc. The objectives of this study were to: (i) build a dynamic simplified model and validate its precision experimentally; (ii) implement advanced model predictive control (MPC) on RFCUV system; and (iii) demonstrate MPC control performance by comparing with existing conventional proportional-integral-derivative (PID) experimentally. Experimental results indicated that under experimental step setpoint variations, the adjusting time of indoor air temperature or operative temperature was only 12 min with MPC controller, and was 30 min with PID controller; it took only 1 min to reach recommended thermal comfort range with MPC controller, and 17 min with PID controller. During 9:00 to 17:00 in typical design day of Nanjing city, compared with PID controller, MPC controller yielded 17.5% energy saving when maintaining equal or better indoor comfort. Thus, compared with PID, MPC demonstrated the advantages of rapid responses, good stability and excellent energy saving effect in RFCUV system.

[en] Recently, inwardly propagating waves (called antiwaves, AWs) in nonlinear oscillatory systems have attracted much attention. An interesting negative refraction phenomenon has been observed in a bidomain system where one medium supports forwardly propagating waves (normal waves, NWs) and the other AWs. In this paper we find that negative refraction (NR) in nonlinear media has an asymmetric property, i.e., NR can be observed only by applying wave source with proper frequency to one medium, but not the other. Moreover, NR appears always when the incident waves are dense and the refractional waves are sparse. This asymmetry is a particular feature for nonlinear NR, which can neither be observed in linear refraction processes (both positive and negative refractions) nor in nonlinear positive refraction. The mechanism underlying the asymmetry of nonlinear NR are fully understood based on the competition of nonlinear waves.

[en] Highlights: • An integrated diagnosis and treatment system based on NGO/USPIO was established. • Nano graphene oxide (NGO) for chemo-photothermal anti-tumor therapy. • USPIO for diagnosing the tumor and confirming the carrier at the tumor site. Due to increased requirements for precision cancer treatment, cancer chemotherapy and combination therapies have gradually developed in the direction of diagnosis and treatment integration. In this study, a non-toxic nano carrier that demonstrates integrated MRI signal enhancing performance, as well as better chemotherapy and photothermal conversion performance, was prepared and characterized. Furthermore, the carrier was used to construct an integrated system of tumor diagnosis and treatment. Our in vitro studies showed that this system has a considerable inhibition effect on tumor cells during the treatment of chemotherapy when combined with PTT, and in vivo studies showed that the system could improve the MRI signal of the tumor site with application of a safe dosage. Thus, this system based on NGO/USPIO has the potential to be a multi-functional nano drug delivery system integrating diagnosis and treatment benefits and applications that are worthy of further research.