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To improve the fuel economy and reduce the exhaust emissions of a hybrid electric city bus (HECB) with dual planetary gear, a vehicle model is proposed based on the coupling mechanism between engine and battery motor in the gear. Then, two kinds of adaptive equivalent consumption minimization strategy (ECMS) algorithms based on fuzzy proportional-integral (PI) controller: Fuzzy PA-ECMS and Fuzzy MPGA-ECMS (MGPA: multiple population genetic algorithm), are established to improve the control effect of ECMS with equivalent factor (EF) as the core. Firstly, an approximate expression of optimal EF is derived based on the Pontryagin’s minimum principle (PMP). Subsequently, the deviation between the reference state of charge (SOC) and the actual SOC and the corresponding variation rate are calculated, which are combined with the fuzzy logic controller to adjust the EF. Finally, the driving style is introduced to rectify the trajectory of EF. According to different driving conditions (different initial values of SOC), the PI parameters of EF are optimized offline by multiple population genetic algorithm. Meanwhile, the interval of PI parameters is continuously optimized by the fuzzy controller. Then, simulation experiments are conducted to verify the efficacy of the two proposed algorithms. The simulation results show that compared to the conventional bus and rule-based control strategy, the proposed Fuzzy PA-ECMS algorithm can improve the fuel economy of bus by 41.70% and 5.29%, respectively. Further, compared to Fuzzy PA-ECMS, Fuzzy MPGA-ECMS algorithm can improve the fuel economy of bus by 0.3%.

Rational design of efficient lanthanide-doped down-shifting nanoparticles (DSNPs) has attracted tremendous attention. However, energy loss was inevitable in the multiple Ln3+ doping systems owing to complex energy migration processes. Here, an efficient NaErF4@NaYF4@NaYF4:10%Nd@NaYF4 DSNP was tactfully designed, in which a buffer layer of NaYF4 was modulated to restrict the interionic energy migration between Er3+ and Nd3+; meanwhile, the surface defects were passivated by an outermost layer of NaYF4. Therefore, the as-prepared DSNPs exhibited two intensive near-infrared-II fluorescence emissions of 1525 nm from Er3+ and 1060 nm from doped Nd3+ under 808 nm excitation. Further, a novel ratiometric nanoprobe NaErF4@NaYF4@NaYF4:10%Nd@NaYF4@A1094 was fabricated by coupling an organic dye of A1094 onto the DSNP surface to quench the 1060 nm emission by the efficient Forster resonance energy transfer, while emission at 1525 nm retained. Thereafter, these activatable ratiometric nanoprobes were used for rapid and sensitive detection of peroxynitrite (ONOO-) in vivo.

The “thermal barrier” problem of high-performance nuclear control chips is becoming more and more prominent with the increase of chip integration under the Moore’s Law, liquid cooling is an effective method to solve the problem of high power heat dissipation. This paper provides an analytical model of the flow and heat transfer performance of micro/mini-channel liquid cooling heat sink for high-end chips. The flow resistance model fully considers the friction loss along the way, the contraction and expansion pressure loss of the channel, and the local pressure loss at the entrance and exit; the thermal resistance model includes the spreading thermal resistance brought by the extension of the heat sink base, the conduction thermal resistance of the bottom plate, the convective thermal resistance between the coolant and the heat sink, and the capacity resistance of the coolant. Using this model, combined with numerical simulation, a typical liquid-cooling heat sink is analyzed, corresponding flow resistance and thermal resistance distribution characteristics are evaluated, and the optimal design configuration is given. The results in this paper can serve as valuable reference for the development of micro/mini-channel liquid cooling technology for high-performance chips.

The thermophysical properties of bone cement are important parameters for its application in the orthopedic treatment. This article focused on the thermal evaluation of the low-melting-point metal (BiInSn alloy), which has been proved to be an excellent bone cement. Firstly, the basic thermophysical properties of BiInSn alloys with different melting points were measured. Secondly, 15 fresh porcine femurs placed in the saline bath, bone cements with different melting points and amounts were injected into the bone cavities, respectively. Thermocouples were used to measure the temperature changes of the bone-cement interface and peripheral bone tissue. The possibility of thermal necrosis was evaluated. Moreover, a three-dimensional human knee model was built to numerically assess the effects of thermal parameters, such as melting point and latent heat on tissue temperature distribution. All the experimental and numerical results implied the heat distribution in the tissue depended on the thermal performances of liquid metal bone cement (LMBC). For LMBC of the same melting point, with increased amounts, the damage to the bone tissue is more severe, while for the same amount of different melting point LMBCs, with the higher melting point, which will lead to more serious damage to the tissue. Also, higher latent heat of LMBC has distinct longer solidification process, which may cause irreversible damage to surrounding tissues. Therefore, in the future, for different clinical surgery needs, the appropriate liquid metal bone cement can be obtained by adjusting the thermal parameters.

Hydrogen energy draws increasing concerns as a kind of renewable and clean energy. Liquid metal (LM) activated Al–H2O reaction is recently emerging as an alternative for real-time hydrogen production. In this study, the energy consumption and environmental impact of this newly emerging method are evaluated via the life cycle assessment (LCA), which indicates that the utilization of waste Al could significantly relieve the energy and environmental issues. In addition, conceptual experiments were conducted to verify the feasibility of hydrogen generation from waste Al, and to disclose the hydrogen generation performances of Al samples in different forms. To balance the cost of LM and reaction efficiency, the optimum mass ratio of LM to Al were explored, and the reusability of LM was demonstrated. Further, a SWOT analysis is adopted to interpret the Strengths and Weakness of such hydrogen production method, and to evaluate the Opportunities and Threats it confronts. Overall, waste Al could provide an energy-saving and environmentally friendly approach to produce hydrogen, which is expected to exploit a new way towards the green hydrogen era.

This paper is dedicated to experimentally investigate the liquid galinstan based minichannel cooling for high heat flux and large heat power thermal management. Firstly, a compact electromagnetic pump towards effectively driving liquid metals was developed, which can provide high pressure head up to 100 kPa. Then, the minichannel heat sink was designed and manufactured, with width of channel 1 mm, height of channel 5 mm. Furthermore, the galinstan based minichannel cooling system was established and experimentally tested under different heating loads and pumping powers. The results show that galinstan based minichannel cooling system can dissipate heat with heat flux 300 W/cm2 and heat power 1500 W. And the thermal performance and hydrodynamic characteristic of minichannel heat sink using galinstan as coolant were obtained. It indicates that compared to water based minichannel cooling, galinstan based minichannel cooling can obtain a rather larger heat transfer enhancement, and the pressure losses of galistan based minichannel heat sink is much lower than that of water based microchannel cooling. Moreover, it is also found that heat capacity thermal resistance becomes a rather important factor for the thermal performance of galinstan based minichannel, due to the high thermal conductivity and lower heat capacity of galinstan. Furthermore, the galinstan based minichannel cooling system can operate silently, steadily and smoothly by using electromagnetic pump, which has no moving parts. Overall, the galinstan based minichannel cooling is proven to be a powerful and practical way for the thermal management of high heat flux and large heat power devices.

Most of the existing robots would find it difficult to stretch and transform all parts of their body together due to rigid components and complex actuation mechanisms inside. Here, we presented a highly transformable liquid-metal composite (LMC) that is easy to change shape in large magnitude and resume its original state again according to need. When subject to heating, part of the ethanol droplets embedded in the composite would change phase and then actuate. We demonstrate the flexible transformation of LMC-made octopus from a two-dimensional shape into several predictable three-dimensional shapes freely on a large scale (even up to 11 times its initial height) through remote wireless heating, which needs no sophisticated operating system at all. Further, several designed behaviors, such as movement of octopus and entangling objects of soft robots, are also realized. Theoretical analysis of the heating-induced liquid-vapor transition of the embedded ethanol droplet interprets the mechanisms involved. The present findings open a new way to fabricate functional transformable composites that would find significant applications in developing future generation soft robots.

Space radiation with inherently broadband spectral flux poses a huge danger to astronauts and electronics on aircraft, but it is hard to simulate such feature with conventional radiation sources. Using a tabletop laser-plasma accelerator, we can reproduce exponential energy particle beams as similar as possible to these in space radiation. We used such an electron beam to study the electron radiation effects on the surface structure and performance of two-dimensional material (FePS3). Energetic electron beam led to bulk sample cleavage and damage between areas of uneven thickness. For the FePS3 sheet sample, electron radiation transformed it from crystalline state to amorphous state, causing the sample surface to rough. The full widths at the half maximum of characteristic Raman peaks became larger, and the intensities of characteristic Raman peaks became weak or even disappeared dramatically under electron radiation. This trend became more obvious for thinner samples, and this phenomenon was attributed to the cleavage of P–P and P–S bonds, destabilizing the bipyramid structure of [P2S6]4– unit. The results are of great significance for testing the maximum allowable radiation dose for the two-dimensional material, implying that FePS3 cannot withstand such energetic electron radiation without an essential shield.

In this paper, a novel method for determining the main thermophysical properties of phase change materials (PCM) is proposed, which can be called as “T-melting CHF” method. The melting point, fusion latent heat, thermal conductivity, and specific heat capacity in both solid and liquid phase of PCM, can all be obtained simultaneously by only one test. The theoretical fundamentals lying behind are introduced, the measurement apparatus and measurement principles are presented, and corresponding restrictive conditions for high accuracy measurement are provided. Theoretically, the thermophysical properties can be accurately measured by the proposed method if the test module can be perfectly insulated. However, heat loss inevitably exists in practical measurement, it will significantly influence the measuring accuracy, hence a correction method is proposed to improve this situation. A typical low melting point metal (gallium) and a typical organic PCM (n-eicosane) were tested to verify the feasibility and accuracy of the method. The experimental results agree well with the reference data reported in the literature. Compared with conventional measurement techniques, the method proposed here has advantages such as simple structure, low cost and high measurement speed; more importantly, it is able to measure multiple properties simultaneously.

Supplemental Document

Ischemic stroke is a devastating disease resulting in high morbidity and mortality. To date, its early diagnosis still faces challenges. Herein, an efficient detection strategy is proposed, in which a targeted activatable NIR-IIb nanoprobe (V&C/PbS@Ag2 Se) is constructed for in vivo highly sensitive detection of early ischemic stroke in a photothrombotic stroke model. At first, the fluorescence of V&C/PbS@Ag2 Se displays an "off" state due to the competitive absorption of excitation irradiation between Cy7.5 fluorophores and PbS@Ag2 Se quantum dots (QDs). Upon intravenous injection, the V&C/PbS@Ag2 Se quickly accumulates in the lesion regions based on VCAM1 binding peptide target to the inflamed vascular endothelium of ischemic stroke. Later, the nanoprobes can be rapidly activated via Cy7.5 oxidation by peroxynitrite (ONOO- ), the prodromal biomarker of ischemic stroke, instantly illuminating the lesion regions. Such a targeted activatable strategy offers a favorable approach for in vivo early real-time assessment of ischemic stroke, which can be expanded to other diseases as a general mothed for in vivo precise diagnosis.

In this paper, BP neural network (BPNN) is studied to model and predict NOX emission of direct injection diesel engine. The model selects four parameters as input, namely rotation speed, load, exhaust temperature and fuel-air ratio. Through testing, it is concluded that the prediction performance of BPNN model will be greatly affected by the initial weight and threshold, so that the prediction accuracy of the model is not high. In order to reduce the influence of initial weight and threshold on the prediction performance of BPNN model, this paper adopts Particle Swarm Optimization (PSO) algorithm to optimize the initial weight and threshold of BPNN, and establishes the corresponding prediction model of NOX emission of diesel engine. The results show that the prediction model of BPNN optimized by PSO algorithm can effectively reduce the influence of initial weight and threshold on BPNN and make the prediction results of the model more reliable. In particular, when PSO adopts non-linear dynamic weight strategy and synchronous learning factor strategy, the prediction performance of BPNN model is more provided with reliability.

The molecular mechanism of alopecia areata (AA) is still elusive and here we utilized bioinformatics methods to analyze AA-related differentially expressed genes. In this study, GSE45512 and GSE45513 were downloaded from the NCBI sub-database Gene Expression Omnibus (GEO). The gene expressions of AA and normal samples were analyzed using the R package limma, which showed significant differences between AA and normal samples in two species. These genes were subject to functional annotation and protein interaction networks. At the same time, gene set enrichment analysis was conducted for all differentially expressed genes. The study revealed that a total of 225 differentially expressed genes were screened from human AA samples, and a total of 337 differentially expressed genes were screened from spontaneous AA skin samples in C3H/HeJ mice. There are 23 differentially expressed genes in the two species. GO and protein interaction network analysis shown gene enrichment in immune-related functions, and these proteins interact with each other. Gene set enrichment analysis showed that differential genes from both species were significantly enriched to chemokine signaling pathways, cytokine-cytokine receptor interactions, staphylococcus aureus infection, and antigen processing and presentation. Moreover, the human down-regulated differential gene not only maps to the alopecia in human phenotype ontology, but also maps to the pathologically relevant phenotype of the skin appendage. In brief, 23 significant differentially expressed genes were screened out coexisting in AA human and mouse by bioinformatics methods. In addition, the result demonstrated that AA is closely related to the immune process and skin appendage lesions. These results provide new ideas for the diagnosis and treatment of AA.利用生物信息学方法分析脱发相关差异表达基因,有望帮助了解脱发发生发展的分子机制。本研究从NCBI的子数据库GEO中选择基因表达谱GSE45512和GSE45513数据集,利用R语言limma工具包,筛选出两个物种斑秃样本与正常样本的共同显著差异表达基因。对这部分基因进行功能注释和蛋白互作网络分析,同时对全部差异表达基因进行基因集富集分析。结果发现,人头皮斑秃样本共筛选出225个差异表达基因;C3H/HeJ小鼠自发斑秃皮肤样本共筛选出337个差异表达基因;两个物种的共同显著差异表达基因有23个。GO功能富集分析和蛋白互作网络分析显示,这部分差异基因显著富集于免疫相关功能,并且彼此间存在蛋白互作关系。基因集富集分析显示两个物种的差异基因都能显著富集到趋化因子信号通路、细胞因子受体相互作用、金葡菌感染及抗原加工与呈递通路;而且人的下调差异基因不仅映射到了人类表型数据库的脱发表型,也映射到皮肤附属物病理相关表型。综上所述,本研究通过生物信息方法分析脱发皮肤组织与正常皮肤组织的差异表达基因,最终筛选出23个在人和小鼠中共同存在的显著差异表达基因;此外,分析发现脱发与免疫过程及皮肤附属物病变密切相关,这些结果为脱发的诊断和治疗提供了新思路。.

In this paper, a finned heat pipe assisted passive heat sink based on a newly emerging high performance phase change material (PCM), the low melting point metal (LMPM), was developed for thermal buffering of high power electronics which works intermittently with heat generation rate up to 1000 W (10 W/cm2). Firstly, thermal performances of the PCM heat sink under different thermal shocks (from 200 W to 1000 W) were experimentally evaluated, in comparison with that of an organic PCM which has similar melting point. It was found that, the former one can prolong the working duration 1.4–2.4 times that of the latter one. Then, the performance of the heat sink was improved through reducing the contact thermal resistance and by increasing the fin number. Furtherly, an air cooling radiator was configured to accelerate the solidification process of the PCM module, which makes it capable of maintaining its highest temperature below 85 °C under 1000 W periodic thermal shock (10 min on and 15 min off). Moreover, energy dispersive spectrometer (EDS) analysis was conducted to verify the compatibility of the LMPM PCM and the structural materials. Finally, a simplified numerical model was developed and validated for the currently constructed finned heat pipe assisted LMPM PCM heat sink, which can be much helpful for future practical thermal design and optimization of this kind of thermal buffering module.

A double distribution function lattice Boltzmann method (LBM) with multirelaxation time is implemented to simulate the Rayleigh–Benard convection melting of a typical low-melting-point metal in a r...

We present the first simulation results of a multi-shell target ignition driven by Z-pinch dynamic hohlraum radiation pulse. The radiation pulse is produced with a special Z-pinch dynamic hohlraum configuration, where the hohlraum is composed of a single metal liner, a low-Z plastic foam, and a high-Z metallic foam. The implosion dynamics of a hohlraum and a multi-shell target are investigated separately by the one-dimensional code MULTI-IFE. When the peak drive current is 50 MA, simulations suggest that an x-ray pulse with nearly constant radiation temperature (∼ 310 eV) and a duration about 9 ns can be obtained. A small multi-shell target with a radius of 1.35 mm driven by this radiation pulse is able to achieve volumetric ignition with an energy gain (G) about 6.19, where G is the ratio of the yield to the absorbed radiation. Through this research, we better understand the effects of non-uniformities and hydrodynamics instabilities in Z-pinch dynamic hohlraum.

As a class of newly emerging material, liquid metal exhibits many outstanding performances in a wide variety of thermal management areas, such as thermal interface material, heat spreader, convective cooling and phase change material (PCM) for thermal buffering etc. To help mold next generation unconventional cooling technologies and further advance the liquid metal cooling to an ever higher level in tackling more extreme, complex and critical thermal issues and energy utilizations, a novel conceptual scientific category was dedicated here which could be termed as combinatorial liquid metal heat transfer science. Through comprehensive interpretations on a group of representative liquid metal thermal management strategies, the most basic ways were outlined for developing liquid metal enabled combined cooling systems. The main scientific and technical features of the proposed hybrid cooling systems were illustrated. Particularly, five abstractive segments toward constructing the combinatorial liquid metal heat transfer systems were clarified. The most common methods on innovating liquid metal combined cooling systems based on this classification principle were discussed, and their potential utilization forms were proposed. For illustration purpose, several typical examples such as low melting point metal PCM combined cooling systems and liquid metal convection combined cooling systems, etc. were specifically introduced. Finally, future prospects to search for and make full use of the liquid metal combined high performance cooling system were discussed. It is expected that in practical application in the future, more unconventional combination forms on the liquid metal cooling can be obtained from the current fundamental principles.

Phase change materials have important application value in the fields of heat storage, cold storage, and thermal shock protection of electronic chips. In particular, in the field of chip thermal shock protection, phase change materials can use the solid-liquid phase change process to absorb a large amount of latent heat, thereby suppressing the temperature rise of the chip and preventing it from overheating. At present, there are mainly three types of common phase change materials: organic, inorganic and metallic phase change materials. There exists significant difference in the thermophysical properties of the three types of materials, and their thermal control performance also have their own characteristics. This paper sorts out the main thermophysical data of the three types of phase change materials. Through theoretical modeling and analysis, the thermal control performance of these materials is quantitatively evaluated and compared. For typical chip thermal shock conditions, the three types of phase change materials are compared, and their typical characteristics are intuitively displayed. The research results can serve as value reference for the development of phase change thermal control technology for chips.

A regular polygon twisted tube with CuO nanoparticles distribution in the organosilicone conduction oil is adopted to improve the thermal performance of parabolic trough collectors (PTCs). A comprehensive numerical study is applied to invistigate the thermal performance of 21 kinds of wisted tubes under the Reynolds number ranging from 50 to 102000 when the temperature is 450 K. The novel twisted tubes are considered with the number of twisted tube edges varying from 1 to 8 and twist angle per unit length varying from 0° to 360°. Results show that the thermal performance of PTC can be enhanced obviously by the nanoparticles. The thermal efficiency enhancement increases with the increasing twist angle, and reaches up to about 306% compare with that for the smooth circular tube. A great effectiveness and uniform performance near the wall region is obtained with the designed complex method. The case of twist angle θ =360° has a better thermal performance when it is compared with the ones with other twist angle. The case of twist angle θ=270° with Reynolds number ranging from 3300 to 12200 has a better comprehensive energy-saving performance when it is compared to the cases with other twist angles. At the same heat transfer capacity, the energy consumption is reduced by 50%.

Fluorescence located in 1500-1700 nm (denoted as the near-infrared IIb window, NIR-IIb) has drawn great interest for bioimaging, owing to its ultrahigh tissue penetration depth and spatiotemporal resolution. Therefore, NIR-IIb fluorescent probes with high photoluminescence quantum yield (PLQY) and stability along with high biocompatibility are urgently pursued. Herein, a novel NIR-IIb fluorescent probe of Au-doped Ag2 Te (Au:Ag2 Te) quantum dots (QDs) is developed via a facile cation exchange method. The Au dopant concentration in the Ag2 Te QDs is tunable from 0% to 10% by controlling the ratio of supplied Au precursor to Ag2 Te QDs, resulting in a wide range of PL emission in the NIR-IIb window and a much-enhanced PL intensity. After surface modification, the Au:Ag2 Te QDs possess bright NIR-IIb emission, high colloidal stability and photostability, and decent biocompatibility. Further, in vivo monitoring of the process of angiogenesis and arteriogenesis in an ischemic hindlimb is successfully performed.

In this paper, low melting point metal (LMPM), eutectic alloy Bi 31.6 In 48.8 Sn 19.6 ( E -BiInSn), was adopted as phase change material for potential thermal management applications. First, E -BiInSn was prepared and its main thermophysical properties were characterized. Then, transient thermal performances of E -BiInSn based heat sinks with internal crossed fins were tested, in comparison with that of organic PCM (octadecanol) which has close melting point. Three types of heat sink structures which have different number of internal fins were studied. Three heating conditions were applied, namely 80 W (2.2 W/cm 2 ), 200 W (5.6 W/cm 2 ) and 320 W (8.9 W/cm 2 ). For all of the cases, E -BiInSn exhibited much superior thermal performance than that of octadecanol. Furthermore, cyclic test of the E -BiInSn heat sink was carried out, which showed good repeatability and stability, and without supercooling. Finally, a simplified 3D conjugate numerical model was developed to simulate the melting process of LMPM heat sink, which showed good agreement with the experimental results. This simplified model would be much useful in practical thermal design and optimization of LMPM heat sink, for that it would significantly save the computational time consumption.

In this paper, the low melting point metal phase change material (PCM) heat sink for coping with ultra-high thermal shock (10 2 W/cm 2 ) is developed and optimized theoretically and numerically. Gallium is selected as the best PCM candidate from the point of view of thermal performance based on an approximate theoretical analysis, and gallium based PCM heat sink with internal copper fin is configured. Different fin structures, namely plate fin, crossed fin and pin fin are investigated and compared; the effects of fin number, fin width and base thickness are parametrically studied; the influence of the structural material is briefly discussed. For arbitrarily given heating condition, the optimal geometric configuration of the heat sink is suggested and corresponding thermal performance is provided. The proposed low melting point metal PCM heat sink can cope with very large thermal shock like 100 W/cm 2 (1 s) with maximum device temperature of 46 °C, under the ambient temperature of 25 °C, which is extremely difficult to deal with otherwise by conventional PCMs. The conclusions drawn in this paper can serve as valuable reference for thermal design and analysis of PCM heat sink against ultra-high thermal shock.

This paper is dedicated to present a comprehensive comparison and discussion on the flow and thermal modeling of micro/mini-channel heat sink for better understanding and further sophistication of this technology. A general optimization process for the flow and thermal performance of micro/mini-channel heat sink is developed, for water cooling and liquid metal cooling both in micro scale and millimeter scale together. Numerical calculation is adopted in the optimization process and serves as baseline for the comparison of different correlations, while 1D thermal resistance model is used for thermal analysis. Appropriate correlations are recommended and optimal parameter selections and suggestions are provided for practical design. Liquid metal cooling and water cooling are compared in mini-channel heat sink, the former exhibits much superior flow and thermal performance. For water cooling, 1D model works well. While for liquid metal cooling, significant deviation exists between the model and the numerical results, and more experimental and analytical works are needed for the thermal design of this kind of coolant.

Recent studies have disclosed that liquid metal (Ga–In alloy) can be applied to activate aluminum in electrolytes to generate hydrogen at room temperature. To present a close to reality experimental demonstration of this method and to realize a continuous reaction between an Al plate and seawater, the liquid metal GaIn10 alloy is adopted to directly erode the surface of the Al plate. Then the eroded Al plate is immersed into NaCl solution (simulated seawater) to produce hydrogen. The results indicate that the existence of gallium can accelerate the average H2 production rate. In addition, the average hydrogen generation rate increased from 3 × 10−5 L s−1 to 4.5 × 10−4 L s−1 as the temperature rose from 20 °C to 80 °C when the corrosion area of the Al plates was 1 × 10−4 m2. However, the H2 production first increased and then decreased with the increase of NaCl concentration. The average hydrogen generation effectiveness is 0.71 L g−1 in the aluminum–water reaction in 5% NaCl solution at 20 °C within 20 min. Over the experimental process, the capability of producing hydrogen has a linear relationship with the corrosion area on the surface of the Al plates corroded by the liquid metal. This work suggests good prospects in the future practice of large-scale hydrogen generation using Al and seawater as reaction sources.

Based on a latest finding on Al-water reaction, we studied the hydrogen production behaviors activated by gallium based liquid metal where the mass percentage of Al was less than 1% in an alkaline environment. Three kinds of room temperature liquid binary alloy including Ga–In, Ga–Sn and Ga–Zn were tested and compared with pure gallium. It was shown that the hydrogen production rate activated by Ga–In alloy was far below than that of pure gallium, while Ga–Sn and Ga–Zn run slightly slower. Aiming to optimize the catalytic performance of pure gallium, we further performed researches to clarify its practical features. We divided five times to add equivalent Al block into pure gallium and found that the rate and quantity of hydrogen production kept unchanged in each batch addition, which suggested that liquid metal as catalyst was activated continuously without impurities mixing to impede catalytic effect. In addition, components analysis of the residual precipitates after reaction with XRD also indicated that there was only Al(OH)3 but no gallium or its derivatives. These findings as clarified by this article can help guide future high performance hydrogen generation and reuse of the liquid metal catalyst.

It is of great scientific and practical significance to explore and imitate the rhythmic oscillating behaviors. Achieving oscillating behaviours via liquid metal is regarded as an excellent strategy and the "mercury beating heart" is a well-known representative. However, the oscillating behaviours achieved over the past few decades either require external power supply or exhibit low frequency. Here, intriguing Al-assisted high frequency self-powered oscillations of liquid metal droplets were discovered and the general mechanisms were interpreted. For this dynamic process, Al is added into the liquid metal for generating gas and activating liquid metal by forming countless tiny galvanic cells and an iron plate is used to passivate the liquid metal via electrochemical oxidation. Therefore, the high frequency self-fueled oscillations can be achieved due to the synergistic effect of these two factors. Furthermore, we predict and confirm that the oscillating behaviors can also be achieved on other eligible substrates (e.g., Ni plate) based on the proposed universal mechanism. The ability to achieve high frequency oscillations of liquid metal droplets promises rich opportunities in developing self-powered soft oscillators.

Fluorescence-guided cytoreductive surgery is one of the most promising approaches for facile elimination of tumors in situ, thereby improving prognosis. Reported herein is a simple strategy to construct a novel chainlike NIR-II nanoprobe (APP-Ag2 S-RGD) by self-assembly of an amphiphilic peptide (APP) into a nanochain with subsequent chemical crosslinking of NIR-II Ag2 S QDs and the tumor-targeting RGD peptide. This probe exhibits higher capability for cancer cell detection compared with that of RGD-functionalized Ag2 S QDs (Ag2 S-RGD) at the same concentration. Upon intraperitoneal injection, superior tumor-to-normal tissue signal ratio is achieved and non-vascularized tiny tumor metastatic foci as small as about 0.2 mm in diameter could be facilely eliminated under NIR-II fluorescent imaging guidance. These results clearly indicate the potential of this probe for fluorescence-guided tumor staging, preoperative diagnosis, and intraoperative navigation.

Phase change materials (PCM) are wildly investigated and used in the fields of thermal energy storage and thermal control of electronics. Numerical simulation is an important method in the research, development, analysis and design of PCM based systems. At present, there are two main numerical methods for the simulation of solid-liquid phase transition problems with natural convection: the finite volume method (FVM) based on macroscopic scale continuity equations, and the lattice Boltzmann method (LBM) based on mesoscopic scale lattice Boltzmann equation. In this paper, the calculation characteristics, speed, efficiency, and accuracy of the two numerical methods are compared, with the classical solid-liquid phase change heat transfer experimental results as benchmark reference. The results obtained in this paper can be used as valuable reference for the selection and use of numerical simulation methods in the study of solid-liquid phase transition problems.

In the process of sailing, the frictional resistance of underwater objects must be reduced, which is of great significance for improving speed, range and saving energy. Based on the inspiration of the shark breathing process, this paper simplified the water spray process from the external bronchial slit of the shark breathing to the cross-flow lateral jet process. By establishing a numerical model, the influence mechanism of the jet on the flow resistance was studied, and by analyzing different jet velocities, the change of viscous resistance reveals the influence of jet velocity on viscous resistance. The results show that the side jet can reduce the boundary layer on the surface of the object, thereby having a drag reduction effect, and the drag reduction rate can be about 10%. In addition, as the jet velocity increases, the drag reduction effect is enhanced, and at the back of the jet port the vortex is formed, the outlet pressure is reduced, and the drag reduction effect is strengthened. At the same time, the study found that the arc-shaped jet port is more conducive to the reduction of resistance.

The conjugate heat transfer from in-furnace combustion to in–tube supercritical fluid has been numerically investigated in this study. The mathematical model of the conjugate heat transfer process has been constructed. The effects of the abnormal heat transfer phenomena of supercritical fluid in tube and combustion status change in the furnace on the conjugate heat transfer process were analyzed. The results demonstrate that the Renormalization-group (RNG) model has better prediction ability. The Abe-Kondoh-Nagano (AKN) model will have an over-prediction problem for the abnormal heat transfer. The RNG model is also more accurate in simulating the combustion process in the furnace.

Ag2 Se quantum dots (QDs) as an effective biological probe in the second near-infrared window (NIR-II, 1000-1700 nm) have been widely applied in bioimaging with high tissue penetration depth and high spatiotemporal resolution. However, the ions deficiency and crystal defects caused by the high Ag+ mobility in Ag2 Se crystals are mainly responsible for the inefficient photoluminescence (PL) of Ag2 Se QDs. Herein, a tailored route is reported to achieve controllable doping of Ag2 Se QDs in which Ag is exchanged by Pb via cation exchange (CE), which is unattainable by direct synthetic methods. The Pb-doped Ag2 Se QDs (denoted as Pb:Ag2 Se QDs) present fire-new optical features with significantly enhanced PL intensity of 4.2 folds. Photoelectron spectroscopy confirms that Pb acts as an n-type dopant for Ag2 Se QDs and therefore the electronic impurities provide additional carriers to fill the traps. Moreover, the general validity of this method is demonstrated to convert different sized Ag2 Se into Pb:Ag2 Se QDs, so that a wide range of NIR-II PL with high intensity is obtained. The bright NIR-II emission of Pb:Ag2 Se QDs is further successfully performed in lymphatic system mapping.

Low melting point metals (LMPMs) are a new kind of phase change materials (PCMs) which exhibit excellent heat extraction capability due to their high thermal conductivity. Such a characteristic renders it distinctive melting mode which hardly exists in conventional paraffin PCMs. In this paper, comprehensive numerical investigation is carried out to reveal the melting process of LMPMs. First, comparative simulations of typical paraffin eicosane and typical LMPM gallium is conducted. Then, dimensionless analysis is performed based on a series of parametric studies and corresponding dimensionless correlations are given under both constant wall temperature condition and constant heat flux condition. Further, the critical dimensionless values within which the correlations are applicable are suggested. Finally, a preliminary exploration is performed to illustrate the influence of natural convection under relatively high Ra number condition. This study can serve as a valuable reference for future practical thermal design of LMPMs based thermal management systems and thermal energy storage systems.

Thermal management especially cooling of electric vehicles (EVs) battery pack is of great significance for guaranteeing the performance of the cells as well as safety and high-efficiency working of the EVs. Liquid cooling is a powerful way to keep the battery temperature in a proper range. However, the efficiency of conventional liquid cooling is still limited due to the inherently low thermal conductivity of the coolant which is usually water or aqueous ethanol. In this paper, a new kind of coolant, liquid metal, is proposed to be used for the thermal management of the battery pack. Mathematical analysis and numerical simulations are conducted to evaluate the cooling capability, pump power consumption and module temperature uniformity of the liquid metal cooling system, in comparison with that of water cooling. The results show that under the same flow conditions, a lower and more uniform module temperature can be obtained and less pump power consumption are needed in the liquid metal cooling system. In addition, liquid metal has an excellent cooling capability coping with stressful conditions, such as high power draw, defects in cells, and high ambient temperature. This makes it a promising coolant for the thermal management of high driving force EVs and quick charge batteries.

Hydrogen is a kind of promising clean energy with huge potential values for human being. Developing a convenient real-time and on-demand hydrogen production and utilization method is critical for its wide practices. Liquid metal was recently found to be able to easily activate aluminum in aqueous solution to continuously and quickly generate hydrogen at room temperature, and thus provides a straightforward hydrogen production way. To further improve this technology, we are dedicated here to investigate the effects of the container substrate on such hydrogen generation process. An interesting phenomenon was found that metal substrate material would evidently enhance the hydrogen generation rate. For conceptual illustration purpose, comparative experiments were conducted to demonstrate the different hydrogen evolution modes between the present method and former approach, and the enhancement mechanism lying behind was revealed. In addition, the influence of the surface roughness of the substrate on the hydrogen production performance was also clarified. The present finding would help motivate an improved extremely simple, straightforward and low cost way for the liquid metal assisted aluminum hydrogen production.

As a class of newly emerging functional material, Gallium based liquid metals have attracted increasing attentions in many fields, such as chip cooling, printed electronics and microfluidics, etc. Particularly, the motion control of liquid metal droplet has been recently tried for its importance in microelectromechanical system (MEMS), microfluidics and potential use in micro-machine or reconfigurable soft robot. This paper is dedicated to explore the motion behavior of liquid metal droplet under AC electric field. The quickly induced oscillation phenomena of liquid metal droplet and surrounding electrolyte solution were observed and the major factors to influence such behaviors are theoretically interpreted and experimentally investigated, including the size of the liquid metal droplet, electrode voltage, electrolyte solution concentration and AC signal frequency etc. Moreover, some typical features to distinguish AC filed actuation with DC field are observed, such as intensive fluid waving induced by the resonance stimulation, and the efficient inhibition of solution electrolysis. Finally, two important applications of adopting AC induced surface oscillation of liquid metal droplet to develop solution mixer as well as fluidic pump were demonstrated which successfully avoid gas generation inside electrolyte environment. The bulk oscillation effects of liquid metal as clarified here could be very useful in a variety of areas such as solution disturbance and mixing, and fluid oscillator or pump etc.

Fluorescence in the second near-infrared window (NIR-II, 900-1700 nm) has drawn great interest for bioimaging, owing to its high tissue penetration depth and high spatiotemporal resolution. NIR-II fluorophores with high photoluminescence quantum yield (PLQY) and stability along with high biocompatibility are urgently pursued. In this work, a Ag-rich Ag2 Te quantum dots (QDs) surface with sulfur source is successfully engineered to prepare a larger bandgap of Ag2 S shell to passivate the Ag2 Te core via a facile colloidal route, which greatly enhances the PLQY of Ag2 Te QDs and significantly improves the stability of Ag2 Te QDs. This strategy works well with different sized core Ag2 Te QDs so that the NIR-II PL can be tuned in a wide range. In vivo imaging using the as-prepared Ag2 Te@Ag2 S QDs presents much higher spatial resolution images of organs and vascular structures as compared with the same dose of Ag2 Te nanoprobes administrated, suggesting the success of the core-shell synthetic strategy and the potential biomedical applications of core-shell NIR-II nanoprobes.

This paper is dedicated to investigate the integrated cooling modality that the spherical low melting point metal (LMPM) macrocapsules were introduced and filled as phase change material (PCM) into a convective cooling heat sink. The fluid-solid heat transfer process coupled with phase change in the packed bed was numerically calculated based on the local thermal non-equilibrium theory and the effective specific heat capacity model which were validated in advance by conceptual experiments. The thermal management ability of composite heat sink packed with spherical LMPM-PCM macrocapsules under typical operating conditions has been revealed. In addition, the influences of different stacking patterns of LMPM particles, particle diameter and inlet velocity on the heat transfer enhancement in the packed bed were comprehensively investigated, respectively. It is found that compared with convective cooling heat sink alone, the composite heat sink filled with LMPM-PCM macrocapsules presents excellent thermal management performance. The temperature increment of heat source in the pulse heat load is reduced by 73.4%, which fully demonstrates the advantages of filling spherical particles. Besides, the Orthoclinal Stacking method achieves the largest volumetric heat transfer coefficient among different stacking patterns of equal-diameter spherical LMPM-PCM macrocapsules. What is more, the plateau duration of the solidification is gradually shortened with the decreasing diameter of the spherical LMPM-PCM macrocapsules and the increasing inlet velocity, which is advantageous for the system to quickly rehabilitate to normal operating temperatures during the de-pulse stage. Overall, this novel integrated cooling modality is proven to be a powerful and practical way to sustain extreme thermal management challenge.

Gallium, a typical room temperature liquid metal, has high thermal conductivity and large volume fusion enthalpy. These characteristics make it a promising phase change material (PCM). However, the significant supercooling of gallium has obstructed its wide application. Adding nucleating agents is a commonly adopted method to reduce supercooling, while the study of nucleating agents for liquid metal is rarely reported so far. In this paper, the influences of the thermal history and the particle size of nucleating agents on the supercooling of gallium were systematically investigated. After that, several particles, such as TeO2, CaO, MgO, iron, and copper were selected as nucleating agents for experiments. The lattice constant was found as one of the most important parameters when selecting nucleating agents. In addition, a more favorable wettability of the nucleating agents with gallium also contributed to the restraint of supercooling. The experimental result showed that the addition of TeO2, whose lattice constant appears as the most similar to that of α-Ga, had the best effect for reducing the supercooling of gallium. The largest reduction of supercooling occurred when 0.5 wt.% TeO2 was added, and more additions resulted in particle agglomeration and a lower nucleation effect. This paper provides important routes for the selection of nucleating agents for gallium, which will benefit for future applications of liquid metal in building heat storage, thermal comfort maintenance and thermal management.

surgery, orthopedic cast is often implemented to stabilize and fix anatomical structures like broken bones. Plaster could harden after mixed with water, thus it is commonly utilized with cotton bandage to form a solid structure to encase a limb or other body parts. As plaster is heavy and impervious, cast could easily result in itching, rashes, allergic contact dermatitis or other cutaneous complications. In this paper we present a novel implementation for surgical fixation with low melting point alloy (LMPA) stuffed in silicone tubes, which is dubbed "LMPA enhanced bandage The alloy is heated by an enameled copper wire to alter the stiffness. When the alloy is in solid state, the bandage could withstand high load without significant deformation, while if heated to its melting point, the entire bandage would soften. We present several conceptual experiments to evaluate the mechanical performance and body fixation of the proposed bandage. Phase change process and temperature variation were recorded by an infrared camera. Preliminary results showed that the present fixation bandage design owns sufficient mechanical strength and necessary thermal response performance to meet the requirement of clinical applications.

The realization of serpentine locomotion has been a core goal pursued. Here, a straightforward approach was discovered to generate the serpentine locomotion based on a brand-new phenomenon observed on liquid metal (Ga67In21Sn12). The dynamic process that liquid metal can automatically produce and move like tremendous slim snakes was revealed and the underlying mechanisms were clarified and interpreted. It was found that the self-growing serpentine locomotion of liquid metal is driven by the localized surface pressure difference related to the unbalanced surface tension. The present work offers new insight and forms in developing future autonomous soft systems and bionic multifunctional robots.

As newly emerging functional materials in the field of chip cooling and thermal management, liquid metals are attracting increasing attentions over the world in recent years. Typical advancements have been found in the categories which span from high-performance liquid metal convection cooling technology, low melting point metal phase change material, metallic thermal interface material, liquid metal pump, and self-driven liquid metal energy harvester/heat sink, and so on. Benefitting from their outstanding heat extraction and transport capability over conventional coolants, liquid metals are expected to break through the bottlenecks facing current cooling strategies and thus cope well with the extremely high-flux cooling requirements. This chapter is dedicated to interpret the progresses of the liquid metal–enabled sciences and technologies in chip cooling and thermal management. The developmental history, the basic concepts, and the main fundamental knowledge thus involved are presented. Some challenging issues and future prospects along this direction are outlined.