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Nano-sized FOX-7/ZIF-8 composites are successfully prepared by a liquid-assisted mechanochemical route. They exhibited fast decomposition and reduced mechanical sensitivities.

A hybrid photovoltaic and thermoelectric device can effectively increase utilization of solar systems. In this article, an analytical model to evaluate the fatigue cracking and its effect on electric power of a hybrid photovoltaic-thermoelectric device is proposed. Both the analytical and simplified expressions of crack length and electric power versus the cyclic number are presented. It is found that combining thermoelectric module with photovoltaic cell of a small temperature coefficient 0.001 K-1 can improve the total electric power by 7.8%. Inclusion of thermoelectric module with photovoltaic cell of a large temperature coefficient 0.004 K-1 reduces the total electric power by 3.3%. The electric power of the hybrid device is inversely proportional to the cyclic number. For photovoltaic cells with small temperature coefficient, the total electric power decreases with crack propagation. The total electric power increases with crack propagation for photovoltaic cells of large temperature coefficient. The thickness ratio of photovoltaic cell to the insulating layer is optimized to eliminate the interlaminar shear stress thus greatly enhance lifetime. Lifetime of the hybrid devices can be availably improved by appropriately increasing thickness of the insulating layer. The optimized length of thermoelectric module for obtaining the maximum electric power output is given.

Under atmospheric pressure, a synthesis of glycerol carbonate was achieved in the one-pot reaction of CO2, glycerol, and styrene oxide with a 94% yield.

Deep eutectic solvents (DESs) have the advantages of low cost, non-toxicity, and biodegradability for the catalytic conversion of fructose to 5-hydroxymethylfurfural (5-HMF).

The advance of space technology is deeply affected by the breakthrough of high-performance fuels. Hypergolic ionic liquids (HILs) are one of the most potential fuels for bipropellant systems. However, high viscosity value and low specific impulse of traditional N-based HILs limit their application. Recently, boron-based HILs with low viscosity become the new candidates, and their derivatives are also found to promote the hypergolicity as additives in HILs. Here, the synthesis, physical chemical properties and thermal performance of boron-based HILs and HIL-additive system are reviewed.

The lithium-sulfur battery (Li–S) is a promising energy storage system with many advantages over the commercialized lithium-ion battery. It has a high theoretical capacity of 1675 mAh g−1, a high theoretical energy density (2600 Wh kg−1), and is eco-environmentally friendly. Although only a small amount is used (

The lithium–sulfur (Li–S) battery is considered one of the most promising technologies for next-generation energy storage. To realise its practical applications, electrodes with high areal sulfur loading, low-cost raw materials, and easily accessible fabrication processes are essential. Herein, we demonstrated the effectiveness of a commercially available black pigment, titanium black (TiB), as a multi-functional additive for sulfur electrodes. Benefiting from the amphipathic nature of TiB, it was easy to obtain a homogenous coating on a current collector (>4 mg cm^(−2)) by applying a traditional slurry containing aqueous carboxymethyl cellulose/styrene-butadiene rubber as a binder. Contact angle measurements revealed much better electrolyte wettability for the electrode with the addition of TiB. Combined with a sparingly solvating electrolyte based on sulfolane and Li[N(SO_2CF_3)_2], the electrode showed excellent cycling performance and high coulombic efficiency at a relatively high current density. Finally, pouch cells were fabricated with a low electrolyte/sulfur (E/S) ratio of 3.2 μL mg^(−1), and a high energy density of 280 W h kg^(−1) was achieved. Subsequent investigation of the gassing behaviour revealed that swelling of the charged cells at 60 °C was suppressed for half a month. This study may pave the way for designing Li–S batteries with practical utility.

Deep eutectic solvents (DESs) are emerging as green and sustainable solvents for the efficient extraction of bioactive compounds. In this study, a series of DESs was prepared using choline chloride with natural, renewable organic acids, polyalcohols, or sugars. The physicochemical properties of their aqueous solutions were investigated. Subsequently, evaluation of the extraction of bioactive berberine and palmatine from a traditional Chinese herb, Phellodendri amurensis cortex (PAC), using these DES aqueous solutions was performed in an ultrasound-assisted environment. The morphologies of the raw and treated PAC samples were observed using scanning electron microscopy to determine the extraction efficiency of the ultrasonic bath using different solvents. Antioxidant capacities of PAC extract solutions were investigated by FRAP and ABTS assays. Furthermore, the extraction conditions were statistically optimized using a response surface methodology to improve the yields of the alkaloids, and the antioxidant capacities of the resultant solutions. This study demonstrates that DES aqueous solutions are suitable, green solvents for the efficient extraction of bioactive compounds from Chinese herbs with the aid of ultrasound. The use of DES aqueous solutions can eliminate the requirement of volatile organic compounds, which would reduce the damage to the environment.

The design and fabrication of lithium secondary batteries with a high energy density and shape flexibility are essential for flexible and wearable electronics. In this study, we fabricated a high-voltage (5 V class) flexible lithium polymer battery using a lithium nickel manganese oxide (LiNi

Thermal shock multiple cracking behaviors of re-entrant auxetic honeycombs with a negative Poisson’s ratio are investigated, and the crack initiation and propagation behavior are discussed. An effective macro continuum model is developed to detect the effects of cracking density and microstructures of auxetic honeycombs on the thermal stress and intensity. The microscale tensile stresses in the struts ahead of the crack as functions of the corresponding thermal stress intensity factor (SIF) at the macroscale are evaluated by employing a macro–micro model. Then, a lower-bound method is proposed to assess the critical thermal load of auxetic honeycombs by combining the macro-micro model and the macro continuum model. A significant increase in both transient thermal stress and intensity as the growing cell-wall angle is demonstrated. Results for the maximum thermal SIF as well as the maximum tensile stress in the middle of cracks are calculated as functions of crack density and length. With the identical SIF, the microscale tensile stresses ahead of the crack in honeycombs with smaller cell-wall angles are greater than that in mediums with larger angles due to the more significant crack tip opening displacement. Critical thermal load prediction reveals that the honeycombs with smaller cell-wall angles generally possess more excellent thermal shock resistance. Also, the varying failure modes of different auxetic honeycomb strips under specific thermal load are predicted. The corresponding mechanisms of crack initiation and propagation are revealed.

Redox-responsive ferrocene (Fc)-grafted supramolecular block copolymers functionalized with hyaluronic acid (HA-g-β-CD/Fc-polymers or HAP) or folic acid (FA-g-β-CD/Fc-polymers or FAP) were synthesi...

Cyclopentazolate anions ( cyclo -N5−) have been receiving ever-increasing attention as component of energetic explosives since recent fulfilment of the first stable sample in solid phase and ambient conditions. Herein, we present a new strategy to utilize deflagration reactions of cobalt pentazolate in combination with explosive poly(ionic liquid) (EPIL) for the preparation of Co@N-doped carbon materials with homogeneously distributed cobalt nanoparticle encapsulated by the layers of N-doped carbon sheets. The resultant 5%Co(N5)2-EPIL-900 exhibits high electrocatalytic activities, excellent stability and tolerance to CH3OH towards oxygen reduction reaction (ORR). Moreover, the present approach provides a novel routine for preparation of functional materials from energetic and newly-emerging cyclo -N5−-derived compounds.

The therapeutic efficacy of anticancer drug delivery systems is severely truncated by their low tumor target ability and inefficient drug release at the target site. Herein, we report the design and synthesis of a novel dual-responsive hyaluronic acid-grafted poly(ionic liquid) block copolymer that was able to self-assemble into spherical nanoparticles in water. Then, the doxorubicin-loaded block copolymer produced particles of 100 nm in size as examined using transmission electron microscopy and dynamic light scattering. The hyaluronic acid-grafted block copolymer micelles were efficiently taken up by CD44-overexpressing cancer cells as indicated by the cell counting kit-8 assays, confocal laser scanning microscopy, and flow cytometry experiments. Therefore, the as-prepared block copolymer micelles had good biocompatibility, low toxicity, and high selectivity, thus offering promise for the treatment of various CD44-overexpressing cancers.

Superconducting cables made of high-temperature superconductors have great potential applications in space solar power station. Since the critical current density of high temperature superconductor is dependent of temperature and determines the distribution of the magnetic flux density, temperature change can affect the pinning force. In this paper, model-I crack problem of a long rectangular superconducting slab under thermal effect is investigated. The stress intensity factors of the slab during the field decent of pulsed field magnetization (PFM) and field cooling (FC) are calculated. Compared with that without considering thermal effect, the result shows that once the temperature of the slab rises, the variation of the stress intensity factor will have a peak during the applied magnetic field decent for the PFM. While for the FC, temperature rise causes the stress intensity factor to decrease.

Currently, available nanoscale anticancer drug delivery systems have low targeting and release efficiency, limiting their therapeutic effects. Thus, tumor-targeting nanocarriers for self-assembly of amphiphilic polymer-drug conjugates are urgently needed to improve drug targeting and treatment efficacy. Here, we report the construction of a stable, reduction-sensitive prodrug conjugate based on hyaluronic acid-grafted pH-sensitive doxorubicin (DOX). The amphiphilic prodrug copolymer self-assembled into spherical nanoparticles in aqueous solution and exhibited an average diameter of 150 nm. Prodrug micelles were stable in a normal physiological environment and achieve selective and rapid release under acidic pH and/or high reduction conditions. Cell Counting Kit-8, flow cytometry, and live cell imaging assays showed that the prodrug had high targeting and antitumor activity against CD44 receptors. Moreover, in vivo pharmacokinetics and biodistribution studies showed that the prodrug had a longer circulation time in BALB/c mice and higher accumulation in 4T1 tumors. Interestingly, the prodrug could effectively treat tumors with few side effects. These results showed that the DOX prodrug micelles developed in this study may have great potential in targeted therapy.

The effects of microstructures of foam core on the thermal shock strength of the sandwich slabs are investigated by macro-micro analysis. Each slab has two ceramic matrix composite (CMC) face sheets and an open-cell ceramic foam core. Asymmetric thermal shock fracture is evaluated at the macro continuum level. The position of the danger zone varying with the thickness of face sheets is determined. The finite element (FE) model based on 3D Voronoi tessellations consists of a local micro-scale region surrounding the crack tip. For a calculated stress intensity factor in macro model, the displacements along the boundary of the local model are calculated based on linear elastic fracture mechanics. The thermal shock strength of the sandwich structure is found to be dominated by the cell regularity, the cross-sectional shape of the cell struts and the relative density of foam core. The physical mechanisms responsible for those results are identified. The effective methods to improve the thermal shock resistance of the sandwich structures with ceramic foam core are proposed.

Coatings of porous ceramic foams have potential applications in thermal protection systems of space shuttles. This paper develops a mechanics model for evaluation of thermal stress of porous cerami...

This paper examines the behavior of wrinkling instability of a thermoelectric thin film bonded to substrate. The critical temperature differences for wrinkling occurrence and buckling initi...

The design and synthesis of new hypergolic ionic liquids (HILs) as replacements for toxic hydrazine derivatives have been the focus of current academic research in the field of liquid bipropellant fuels. In most cases, however, the requirements of excellent ignition performances, good hydrolytic stabilities, and low synthetic costs are often contradictory, which makes the development of high-performance HILs an enormous challenge. Here, we show how a fuel-rich boranophosphate ion was rationally designed and used to synthesize a series of high-performance HILs with excellent comprehensive properties. In the design strategy, we introduced the {BH3 } moiety into the boranophosphate ion for improving the self-ignition property, whereas the complexation of boron and phosphite was used to improve the hydrolytic activity of the borohydride species. As a result, these boranophosphate HILs exhibited wide liquid operating ranges (>220 °C), high densities (1.00-1.10 g cm-3 ), good hydrolytic stabilities, and short ignition delay times (2.3-9.7 milliseconds) with white fuming nitric acid (WFNA) as the oxidizer. More importantly, these boranophosphate HILs could be readily prepared in high yields from commercial phosphite esters, avoiding complex and time-consuming synthetic routes. This work offers an effective strategy of designing boranophosphate HILs towards safer and greener hypergolic fuels for liquid bipropellant applications.

Thermoelectric cylindrical shells have been widely used to convert waste heat of exhaust pipe into electric energy. They can also be used in refrigerating process to reduce the surface temperature in thermal protection system in modern supersonic space shuttles. This paper presents a transient model to investigate the dynamic characteristics of laminated thermoelectric cylindrical shells. The internal and external surfaces of the shell are assumed to be stress free. Analytical solutions of temperature, electric potential and thermal stress fields are obtained and are presented graphically. The effects of applied electric current density on the temperature, electric potential and thermal stress distributions are investigated. Numerical results show that the transient-state hoop stress at the internal surface of shell is higher than that of steady state. In addition, the power generation efficiency of thermoelectric shell is improved at a specific external applied electric current density. The models we constructed can evaluate the thermal and mechanical performances of materials subjected to temperatures higher than 1400 K therefore can be applied to many severe heating environments.

A novel family of hydrophobic triaminocyclopropenium cation based ionic liquids have been synthesized, and their structures and physicochemical properties characterized by NMR and IR spectroscopy, elemental analysis, differential scanning calorimetry, and hypergolic tests. The experimental results showed that all of these ionic liquids exhibited the expected hypergolic reactivity with the oxidizer white fuming nitric acid. Among them, the hypergolic ionic liquid based on the cyanoimidazolylborohydride anion showed excellent integrated properties, including high decomposition temperature (194 °C), high density (0.95 g cm-3 ), moderate viscosity (44 MPa s), ultrafast ignition delay time (6 ms), and high specific impulse (301.9 s); this demonstrates its potential as an environmentally friendly alternative to toxic hydrazine derivatives.

New-generation green bipropellants based on ionic liquids for aircraft have attracted the attention of researchers. However, the major defects of ionic liquid propellants are their low specific impulse and incomplete combustion, which limits their practical application. In this work, a series of novel hypergolic fluids were prepared by mixing oxygen-rich nitroglycerin (NG) with fuel-rich dicyanamide-based ionic liquids. The complete dissolution of NG in ionic liquids makes these hypergolic fluids became self-supplying oxygen composite fuels, which generate much less solid residual products than pure hypergolic ionic liquids (HILs). Moreover, the addition of NG inhibited the micro-explosion between fuel and white fuming nitric acid (WFNA), extended the contact time between fuel and oxidizer. And a proper amount of NG in the fuel could suppress the secondary combustion. These composite fuels have high density (>1 g cm−3), low viscosity (as low as 13.49 cP), wide liquid operating ranges and acceptable ignition delay time. Additionally, the specific impulses of the composite fuels were higher than pure HILs. For the first time, this work provides a simple and reliable method to control the ignition properties of HIL by adding oxygen-enriched additives.

This work provides a multi-scale investigation on the punch performance of brittle porous ceramics with a flat, square-ended die. The micro discrete representation of porous ceramics is built by imitating the natural formation process. The macro effective model is established based on continuum mechanics. The effects of thickness and relative density of the porous ceramic layer on the indentation depth and the stress field are predicted. Results from the micro and macro models are in good agreement. The stress singularity at the punch tips is characterized by the stress intensity factor (SIF). The values of SIF increase with the rising thickness and finally level at a constant. A punch toughness concept is proposed by combining the developed micro discrete representation and the macro continuum model to evaluate the indentation resistance of the porous ceramics. The punch toughness varying with the relative density of porous ceramics is provided. Besides, size effect investigation proves that the brittle porous ceramics with larger cell size generally possess a greater punch toughness. The responsible physical mechanisms are revealed by the deformation analysis of individual cells. Meanwhile, when the ratio of specimen length to punch width is less than 3.0, the edge effect in indentation tests cannot be neglected and the punch toughness of the specimen will be underestimated.

This paper studies the energy conversion performance and strength of a wearable thermoelectric generator consisting of a thin thermoelectric layer bonded to a flexible substrate. The thermal conductivity, Seebeck coefficient and electrical resistivity used in this paper are calculated from the fundamental formulas of carrier motion as functions of temperature. This gives more accurate calculating results and in line with actual situation. Convective heat transfer between the thermoelectric layer and the environment and the contact thermal resistance between the thermoelectric layer and the human skin are considered. Analytical solutions of power output density and axial stress in thermoelectric layer are derived. It is found that the bending of thermoelectric layer can increase the open-circuit voltage. The power output density increases to a peak value and then decreases with the length of the thermoelectric layer. On the premise of guaranteeing the strength of thermoelectric layer, the optimized length of the thermoelectric layer for obtaining maximum power output density is given.

This work investigates the indentation resistance of the auxetic/non-auxetic honeycomb ceramics layer by combining a discrete numerical representation and a continuum analytical model. The indentation depth of honeycombs with varying cell-wall angle and cell-wall thickness are measured. The indentation depth of auxetic honeycombs with negative Poisson’s ratio (NPR) is smaller than that of conventional ones in the premise of the same cell-wall thickness. But on the condition that the honeycombs possess the same relative density, there exists an inverse tendency. The corresponding mechanisms responsible for those trends are revealed. The stress intensity factor (SIF) is defined to characterize the stress singularity at the corner of the punch. The influence of NPR on the magnitudes of SIF is evaluated. A punch toughness concept is defined by a novel multi-scale method as the failure criterion of brittle honeycomb ceramics in indentation tests. The effects of NPR on the punch toughness of honeycombs are discussed. And the empirical formulas of punch toughness varying with the cell-wall thickness and the relative density are summarized. Finally, the NPR effects on the collinear punches problem are detected; the results show that the auxetic performance can significantly weaken the interaction between the punches.

This work investigates the effects of cracking on the overall properties of brittle auxetic/non-auxetic honeycombs. The micro numerical model and macro theoretical model are established simultaneously. The analytical expressions of crack opening displacement (COD) are derived and the results agree well with numerical simulations. The fracture toughness of honeycombs is calculated by combining the stress in the numerical model and the stress intensity factor (SIF) in the theoretical model. The reductions in the equivalent stiffness and equivalent thermal stress coefficient (TSC) of the cracked honeycombs are predicted. The negative Poisson’s ratio (NPR) effects on those fracture mechanics parameters and equivalent thermomechanical properties are studied. And considering the orthogonal anisotropic properties of honeycombs, the cracking along two orthogonal directions is examined. It reveals that the significant NPR effects can only be detected in a single direction and the effects in another direction are inconspicuous. In addition, the effects of crack length, medium dimensions, and cell-wall angle of honeycomb cells on the overall performance of the cracked medium are also evaluated by parametric studies and the results are displayed graphically.

Ionic liquids have attracted a great deal of interest in recent years, illustrated by their applications in a variety of areas involved with chemistry, physics, biology, and engineering. Usually, the stabilities of ionic liquids are highlighted as one of their outstanding advantages. However, are ionic liquids really stable in all cases? This review covers the chemical stabilities of ionic liquids. It focuses on the reactivity of the most popular imidazolium ionic liquids at structural positions, including C2 position, N1 and N3 positions, and C4 and C5 positions, and decomposition on the imidazolium ring. Additionally, we discuss decomposition of quaternary ammonium and phosphonium ionic liquids and hydrolysis and nucleophilic reactions of anions of ionic liquids. The review aims to arouse caution on potential decomposition of ionic liquids and provides a guide for better utilization of ionic liquids.

The one-pot reactions of CO2, epibromohydrin, and phenols, thiophenols, or carboxylic acids catalyzed by 1-butyl-3-[(3-hydroxyphenyl)methyl]imidazolium bromide were investigated. Three kinds of cyclic carbonates with ether, thioether, or ester groups were synthesized under mild reaction conditions in good-to-high yields. Reaction-mechanism studies indicated that the proton exchange between the alkoxide formed through the ring-opening reaction of epibromohydrin with 1-bromo-3-phenoxy-2-propanol plays a crucial role in this synthetic route. The catalyst 1-butyl-3-[(3-hydroxyphenyl)methyl]imidazolium bromide was transformed to the corresponding cyclic-carbonate-functionalized ionic liquid during the reaction. This transformation did not affect its catalytic performance in the reaction.

Hierarchical porous poly(ionic liquid)s (PILs) with high specific surface area were firstly synthesized via anion exchange. The exchange of bulky salicylate and its dimers/clusters in PILs by other smaller anions increased the specific surface area and fabricated a hierarchical porous structure. The high specific surface area and hierarchical porous structure prompted a high degree of exposure of the active sites and made the heterogeneous PIL catalysts contact with substrates sufficiently, enhancing their catalytic activity.

A series of C–N linked bistetrazolate nitramino compounds, i.e., 1-(2H-tetrazol-5-yl)-5-nitraminotetrazole (2) and its energetic salts (3–8), were successfully prepared from readily available 5-aminotetrazole. All new energetic compounds were fully characterized by IR and NMR spectra and elemental analysis, and six of them (1, 3–7) were further determined by single-crystal X-ray diffraction analysis. The nitrogen contents of these energetic bistetrazolate compounds, ranging from 59.3% (3) to 74.8% (7), are much higher than those of the commonly used high explosives such as RDX (N: 37.8%), HMX (N: 37.8%) and CL-20 (N: 38.3%). And theoretical calculations by using the Gaussian 09 program package demonstrate that compounds 1–8 have high positive heats of formation, of which the heats of formation of ammonium salt 4 (3.60 kJ g−1), aminonitroguanidinium 5 (3.11 kJ g−1) and dihydrazinium salt 7 (3.25 kJ g−1) are approximately eight times higher than those of RDX (0.39 kJ g−1) and HMX (0.39 kJ g−1), and four times higher than that of CL-20 (0.83 kJ g−1). The high nitrogen contents and high heats of formation have endowed these energetic compounds with prominent detonation performance. It is noteworthy that compound 7 exhibits an excellent calculated detonation velocity of 9822 m s−1 superior to that of CL-20 (9730 m s−1), while the impact and friction sensitivities of 7 (IS = 8 J, FS = 192 N) are comparable to those of HMX (IS = 7 J, FS = 112 N). The good detonation properties with moderate sensitivities demonstrate that compound 7 is a promising candidate for application as a high-performance energetic material.

For the development of energetic materials, insensitive compounds have attracted considerable attention due to their improved safety and lower cost than those of sensitive energetic compounds during production, transportation, and application. In this study, insensitive 4-aminofurazan-3-carboxylic acid amidrazone was used as a cation to obtain four derivatives which were determined by X-ray single crystal diffraction. It is interesting to note that all four derivatives are insensitive to impact and friction, while the velocities of detonation for derivatives are superior to that of insensitive TATB (1,3,5-triamino-2,4,6-trinitrobenzene). Multi-factors analysis shows that the cation of 4-aminofurazan-3-carboxylic acid amidrazone is a promising furazan-based cation in desensitizing energetic compounds.