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The preparation and energy release mechanism of catalyst-coated RDX: (A), diagram of preparation of catalyst-coated RDX based CPs; (B), Dependence of the burning rates (r, mm·s−1) on initial chamber pressures (P, 1–3 MPa) in Ar atmosphere under ambient initial temperature; (C), Flame temperature and burning time at 2 MPa for different CPs. [Display omitted] • High energy density and insensitive qy-RDX hybrid crystals is prepared. • The in-situ synthesis and coating of metal oxides as catalysts on qy-RDX results in greatly improved catalytic efficiency. • The pressure exponent of composite propellants was reduced by 50% by using only 10 wt% of catalyst-coated qy-RDX. High-energy solid propellants with lower pressure exponent, lower burn rate but with high combustion efficiency are usually desired. The use of catalysts in less amount but maintained high efficiency is essential for high-energy content and better combustion performances. The fine combination of catalyst with energetic fillers as oxidizer has been found to be a promising strategy to achieve this goal. In this paper, a widely used nitramine oxidizer, cyclotrimethylenetrinitramine (RDX) has been selected as a typical example, which was first intercalated for lower sensitivity and lower burn rate, and then it was coated with in-situ synthesized nanosized metal oxides as catalysts for lower pressure exponent using polydopamine as the interfacial binding layer. Two types of catalyst-coated hybrid RDX crystals (named as qy-RDX@Fe 2 O 3 and qy-RDX@CuO) have been prepared and characterized. It is found that the in-situ grafted nano-Fe 2 O 3 and CuO crystals have significant catalytic effect on qy-RDX, which increased the heat release of qy-RDX@Fe 2 O 3 and qy-RDX@CuO from 1747 J·g−1 to 2159 J·g−1 and 2133 J·g−1, respectively. The results show that both qy-RDX@Fe 2 O 3 and qy-RDX@CuO could reduce the ignition delay time and largely improve the burn rate of corresponding propellants at lower pressure (e.g. increased from 3.14 mm·s−1 to 5.50 mm·s−1 at 1 MPa) by coating only 0.13 wt% Fe 2 O 3 and 0.15 wt% CuO catalysts, resulting in much lower pressure exponent (from 0.32 to 0.15). In particular, the decomposition heat of propellant containing only 10 wt% of qy-RDX@CuO is 1.5 times higher than the reference blank sample, so that its flame temperature was increased from 1800 °C to 2400 °C due to higher combustion efficiency with more energy release. [ABSTRACT FROM AUTHOR]

The two-dimensional energetic polymer triaminoguanidine–glyoxal (TAGP) has been used in modification of EMs to formation of various hybrid materials for higher density and better stability due to its excellent capability to desensitize high energetic crystals without any energy loss. In this paper, theoretical calculations based on ReaxFF-MD were performed to demonstrate the thermal decomposition mechanisms of TAGP, which has been further proved by experimental results from Pyro-GC/MS analysis. The results show that there are three dominant pathways for the initial decomposition of TAGP, i.e. , the breakage of C-N bond with production of C 2 H 3 ON 2 (most likely to happen), the scission of N-N bond with release of C 2 H 2 ON, and the rupture of N-N bond accompanied with the proton transfer to release C 2 H 3 ON. Therefore, the C 2 H 3 ON 2 , C 2 H 2 ON and C 2 H 3 ON are the dominant initial decomposition products of TAGP, which may gradually transform to the final gaseous products. The experimental results confirmed the presences of these substances. The major final gaseous products of TAGP include N 2 , H 2 , H 2 O, NH 3 , NH 4 , NH 2 , N 2 H, N 2 H 2 , HCN and CO 2 , among which the concentration of N 2 is the highest, relatively higher than H 2 , H 2 O and NH 3. Besides, the initial decomposition rate of TAGP largely depends on its MW. The activation energies for formation of C 2 H 3 ON 2 and N 2 under isothermal conditions has been obtained to further illustrate the effect of MW on the decomposition rate. • Three types of typical TAGP structural models have been constructed according to the measured molecular weights. • The detailed decomposition mechanisms of TAGP have been proposed. • Their final thermolysis products have been mutually confirmed by ReaxFF-MD simulations and Pyro-GC/MS experiments. [ABSTRACT FROM AUTHOR]

• A homogenous polysaccharide SPS60 was isolated from Sabia parviflora. • The monosaccharide component of SPS60 was glucose. • SPS60 showed significant hepatoprotective activity. • The AFM images showed SPS60 was a massive sphere with a diameter of 21 nm. The extraction, purification, structure and hepatoprotective activity of a homogenous polysaccharide (SPS60) from Sabia parviflora were investigated. SPS60 was screened after purification with Sephadex G-100 and showed the excellent hepatoprotective activity. Its structural characteristics were investigated by Time of flight mass spectrometry (TOF-MS), PMP Pre-column derivatization-HPLC (PMP-HPLC), nuclear magnetic resonance (NMR) spectroscopy and Atomic Force Microscopy (AFM). The results showed that SPS60 possessed the molecular weight of 16900 Da and the monosaccharide component was glucose, as well as a 1 → 6 glycosidic bond. The results of atomic force microscopy (AFM) show that SPS60 is a blocky sphere in solution. Furthermore, the SPS60 could significantly improve the survival rate of LO2 hepatocytes which were damaged by CCl 4. Therefore, SPS60 may be an active substance of S. parviflora as a local functional tea. [ABSTRACT FROM AUTHOR]

• Stable multi domain wall states containing two or more domain walls can be obtained based on our microscopic model. • A novel hybrid st ate consisting of two domain walls and one centered vortex tends to emerge as the zero field ground state of the rectangular system. • Complex coreless skyrmionic states with different enclosed structures of domain walls c an appear in the rectangular sample. In the framework of the microscopic Bogoliubov-de Gennes theory, we investigate the topological defect states in mesoscopic chiral p -wave superconducting rectangles. In the absence of applied magnetic field, stable multi-domain-wall states containing two or more domain walls can be obtained with the increase of the aspect ratio of the rectangle at zero temperature. When the external field is applied, the multi-domain-wall state can only be found as the ground state at finite flux. Interestingly, a hybrid state consisting of two domain walls and one centered vortex tends to emerge as the zero-field ground state of the rectangular system. For enlarged applied flux, several coreless skyrmionic states with different enclosed structures of domain walls as well as the half-quantum vortex-antivortex pair can appear in the present sample. [ABSTRACT FROM AUTHOR]

TAGP provide strong interaction which packing RDX recrystallization, in this strategy, the high energy content and insensitive qy-RDX were obtained. • High density qy-RDX hybrid crystals have been designed and prepared under constraint of TAGP. • TAGP inhibited the growth of RDX molecules (111) and (200) planes, resulting in improved energy density. • 2D TAGP can greatly change the crystal structure of RDX thereby significantly reduced its sensitivity. In this paper, the widely used energetic material RDX had been modified with 2D high nitrogen polymer (TAGP). Various hybrid RDX crystals (qy-RDX) with higher detonation velocity and better thermostability had been obtained as a result of strong intermolecular interactions between TAGP and RDX molecules. The performance of the qy-RDX had been characterized to clarify the inherent mechanisms. It shows that the⊿ H f of qy-RDX could be largely changed in the range of 23.4 kJ kg−1 to 1343.6 kJ kg−1, whereas the density varies only from 1.81 g cm−3 to 1.86 g cm−3. The resulted detonation velocities are in the range of 8725.5 m·s−1 to 9251.8 m·s−1, depending on the content and state of the TAGP dopant. The sensitivity of the resulted qy-RDX is much better than pristine RDX due to improved crystal quality as well as higher concentration of hydrogen bonds. The impact energy is improved from 8.5 J (RDX) to 22 J (qy-RDX-1), whereas the friction sensitivity improves form 130 N to over 360 N for the same case. The E a for thermal decomposition of qy-RDX-1has reduced from 147.8 kJ mol-1 (RDX) to (124.5 kJ mol-1), since TAGP dopant could be considered as active catalytic sites after melting of RDX. [ABSTRACT FROM AUTHOR]

• A variety of novel hybrid qy-HMX crystals with different structure have been prepared and evaluated. • The kinetics models governing the rate-limiting thermolysis reactions are obtained. • The structure and thermal reactivity properties of qy-HMX and corresponding mechanism are clarified. In this paper, the 2D (two-dimensional) high nitrogen triaminoguanidine-glyoxal polymer (TAGP) has been used to dope HMX crystals. Various constraint TAGP-doped HMX crystals (qy-HMX) with higher density and better stability have been obtained due to strong constraint interactions between dopant and HMX molecules. The structure and thermal reactivity properties of qy-HMX are unexpectedly largely affected by a slight change in the way of co-crystallization/precipitation under the same precursor conditions. In particular, the density of qy-HMX could be largely changed in the range of 0.94 g cm−3 to 2.12 g cm−3 due to varied doping state, depending on the crystallization conditions. These qy-HMX crystals are more thermally stable than HMX, showing either no polymorphic transition or increased transition temperature. As a typical example, the polymorphic transition of qy-HMX-211 with doping amount of 21.1 wt% was excluded due to formation of a completely new more stable phase of HMX. The qy-HMX-341 has the highest heat release (1869 J g−1), even higher than that of HMX. The average E a (activation energy) for the polymorphic transition of qy-HMX-341 is about 334.1 kJ mol−1, following a random chain scission model (L2), whereas it is 222 kJ mol−1 for HMX. The E a for thermal decomposition of qy-HMX-341 is 215.7 kJ mol−1, which is 39.8 kJ mol−1 lower than that of HMX. Therefore, the qy-HMX crystal has high potential to be used as a promising high explosive to replace HMX for various applications in the future. [ABSTRACT FROM AUTHOR]

Using Bogoliubov-de Gennes formalism, the chiral order parameters in mesoscopic p-wave superconducting noncircular systems are investigated in the absence of applied magnetic field. For the perfect square or rectangular sample, a single-domain-wall state tends to emerge, accompanied by a vertical or horizontal domain wall separating the regions with different chiralities. This type of domain walls can be effectively tuned by temperature and the aspect ratio of samples, and the multi-domain-wall state containing two domain walls can be obtained. Moreover, for a p-wave square loop with a centered hole, the diagonal-symmetric mode for orders is presented, leading to four domain walls placed at the center of four arms of the loop. In particular, several peculiar domain-wall states may show up in the asymmetric square loop system with an off-centered hole. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Formulation of PVDF/CuO/Al is optimized on the basis of maximum heat of reaction. • Electrospinning is employed to fabricate high solid-loading MICs based on PVDF. • Electrospinning and doping of GO can improve the density, heat of reaction, etc. Abstract In this paper, the electrospinning technique has been employed to fabricate PVDF/CuO/Al nanocomposites, where the formulation was optimized on the basis of maximizing the reaction heat with increased efficiency. The graphene oxide (GO) has also been used as both lubricant and catalyst, which is well dispersed inside the PVDF matrix by the electrospinning process as well. It has been found that the smooth PVDF nano-fibers could be fabricated with GO content of 0.5 wt%, where the Al and CuO nanoparticles are also uniformly loaded. In comparison with the n-CuO/n-Al and PVDF/CuO/Al prepared by conventional mechanical mixing method, the GO-doped PVDF/CuO/Al nanocomposites via electrospinning improved heat of reaction, density as well as anti-oxidation capability. In addition, the electrospinning technique and doping of 0.5 wt% of GO can improve the reaction efficiency of PVDF/CuO/Al nanocomposites since they contribute to dispersion of components and homogeneous structure fabrication. [ABSTRACT FROM AUTHOR]

Five new guaiane-type sesquiterpene lactones, caroguaianolide A–E ( 1 – 5 ), along with nine known sesquiterpene lactones ( 6 – 14 ) were isolated from the whole plant of Carpesium abrotanoides L. Their structures were elucidated on the basis of spectroscopic date, HRESIMS analysis, and comparison of experimental and calculated ECD data. All isolated compounds ( 1 – 14 ) were tested in vitro for their cytotoxic activities against the MDA-MB-231, HGC-27 cancer cell lines, of which compounds 1 – 3 , 6 , 7 , 11 and 12 showed significant cytotoxic activities with IC 50 values ranging from 2.67 to 12.34 μM. [ABSTRACT FROM AUTHOR]

• Composite propellants (CPs) containing insensitive high-energy qy-HMX have been prepared. • The qy-HMX-based CPs has 9.64% higher heat of explosion than HMX-based one. • The burn rate of CPs containing qy-HMX is 4.38 mm·s−1 at 3 MPa, 45.9% lower than that of corresponding HMX-based one. • The average particle size of the CCPs of qy-HMX-based CPs is 71.5% lower than that of HMX-based one. Two types of qy-HMX (insensitive HMX with improved energy density, numbered 1 and 2) have been used and studied as an ingredient of HTPB-based composite propellants (CPs), and the decomposition and combustion performances have been investigated. It has been shown that the main exothermic peak temperature of blank CPs containing 21 wt% of qy-HMX-1 is 258.9 °C, which is 4.7 °C higher than that of HMX-containing one, indicating improved thermostability. The corresponding heat of explosion for blank qy-HMX-2-based CPs was measured to be 5830 J∙g−1, which is 300 J∙g−1 higher than that of HMX-based one. Interestingly, the qy-HMX-2-based CPs has higher energy density than corresponding CL-20-based ones, but it has much lower burn rate under the same pressure, e.g. 4.38 mm∙s−1 at 3 MPa for the former vs. 9.03 mm∙s−1 for the latter. Under the effect of typical conventional catalysts such as nano-CuO and nano-Fe 2 O 3 , the qy-HMX-1-based CPs showed increased heat of explosion and higher burn rate. In addition, the particle sizes of condensed combustion products (CCPs) of CPs containing qy-HMX-2 are much smaller than that of HMX-based one, where the Al 4 C 3 was produced as its unique CCPs ingredient. [ABSTRACT FROM AUTHOR]

The theory of selective photothermolysis (SP) is used in many fields of laser surgery and medicine. As several parameters and a number of complicated photothermal interactions are involved in SP, numerical simulations have been providing an important and effective way in SP studies. However, with different photothermal models of SP, simulated results differ considerably. In addition, insufficient attention has been paid to tissue pressure variation during SP in these models, so that vessel rupture and other clinical phenomena cannot be explained. A novel photothermal model of SP was proposed using a Monte Carlo method to simulate the laser transport in the tissue, a heat transfer equation with dynamically changing vaporization temperature to calculate the temperature distribution, and the Arrhenius equation to predict the thermal damage. A factor of trapped vaporized tissue water k was introduced to describe the effects on tissue pressure, temperature, and other related parameters. It was shown that the simulation results are affected significantly by k. Temperature and thermal damage volume are almost identical, respectively, to those obtained with models with vaporization at 100°C and models without vaporization when k = 0 and 1, while thermal damage volume is close to that obtained with models of vaporization at 110°C and 130°C, respectively, when k = 0.022 and k = 0.18. To some extent, the current models without vaporization and models with vaporization at constant temperature can be regarded as special cases at specific situations of this new photothermal model of SP. In addition, more descriptive simulation results, such as temperature, thermal damage, and pressure, are accessible with this model, although the accuracy depends on the value of k, the estimation of which is planned as future work. [ABSTRACT FROM AUTHOR]

A quantitative evaluation method has been developed to study the effects of nanoadditives on thermal decomposition mechanisms of energetic compounds using the conventional thermogravimetry coupled with mass spectrometry (TG/MS) technique. The decomposition of ammonium perchlorate (AP) under the effect of several energetic catalysts has been investigated as a demonstration. In particular, these catalysts are transition metal (Cu2+, Co2+ and Ni2+) complexes of triaminoguanidine (TAG), using graphene oxide (GO) as dopant. They have been well-compared in terms of their catalytic effects on the concentration of the released gaseous products of AP. These detailed quantitative analyses of the gaseous products of AP provide a proof that the proton transfer between ∙O and O2 determines the catalytic decomposition pathways, which largely depend on the type of reactive centers of the catalysts. This quantitative method could be applied to evaluate the catalytic effects of any other additives on the thermal decomposition of various energetic compounds. [ABSTRACT FROM AUTHOR]