High-Energy Composite Fuels with Improved Combustion Efficiency by Using AlH3 Embedded with Al Particles.

Aluminum hydride (AlH3) has attracted much attention due to its potential to replace aluminum (Al) as a novel energetic material in solid propellants. In this research, ammonium perchlorate (AP) and perfluoropolyether (PFPE) as functionalized coatings and a combination of acoustic resonance and spray drying technology have been employed to prepare AlH3@Al@AP (AHAPs) and AlH3@Al@AP@PFPE (AHAPs-F) energetic composite particles. The formulations of composite propellants and modified AlH3 particles were designed and fabricated. Their thermal reactivity, reaction heat, density, vacuum stability, combustion performance, and condensed combustion products (CCPs) have been systematically investigated. The results show that the solid propellants containing AHAPs (SP13) and AHAPs-F (SP14) composites can significantly enhance the reactivity and energy output compared to conventional solid propellants with the mechanical mixture Al/AlH3 (SP12). In particular, the total heat releases of SP13 and SP14 are almost 1.2 and 1.7 times higher than those of conventional ones (SP12, 1442 J g-1), respectively. Among the AlH3-based propellants, SP14 propellants exhibit the highest reaction heat of 5887 J g-1, the most intensive flame radiation of 31.4 × 103, and the highest combustion wave temperature of 2495 °C. Moreover, the particle size distribution of CCPs from SP14 propellants is much narrower and smaller than that of SP12, resulting in higher combustion efficiency.

Stabilization of AlH3 Crystals by the Coating of Hydrophobic PFPE and Resulted Reactivity with Ammonium Perchlorate.

Aluminum hydride (AlH3) is a promising fuel component of solid propellant, but its stabilization is still challenging. Herein, surface functionalization of hydrophobic perfluoropolyether (PFPE) followed by ammonium perchlorate (AP) coating has been implemented. In particular, AlH3@PFPE@xAP (x = 10, 30, 50, or 64.21%) composites (AHFPs) were prepared by a spray-drying technique. The PFPE-functionalized AlH3 with a hydrophobic surface shows an increased water contact angle (WCA) from 51.87° to 113.54°. Compared with pure AlH3, the initial decomposition temperatures of AHFPs were increased by 17 °C, and the decomposition properties of AP in the AHFPs were also enhanced with significantly decreased peak temperature and fairly increased energy output. Moreover, the decomposition induction time of AHFPs-30% was improved by almost 1.82 times that of raw AlH3, which indicates that the coatings of PFPE and AP could improve the stability of AlH3. The maximum flame radiation intensity of AHFPs-30% was 21.6 × 103, which is almost 7.71 times that of pure AlH3 (2.8 × 103).

[Temporal and Spatial Distribution Characteristics and Driving Factors of Denitrification Bacterial Community Structure from Landscape Water in Hebei Province: Taking Shijiazhuang as Example].

Landscape water is an important part of urban water systems, and excessive nitrogen affects its ecological functions. This study aimed to investigate the temporal and spatial distribution characteristics and driving factors of the community structure of denitrifying bacteria from landscape water. The functional gene nirS was used as a functional marker to explore the community of denitrifying bacteria in the water and sediment of landscape water. Based on parameters of the water and sediment, the temporal and spatial distribution characteristics and driving factors of the community of denitrifying bacteria were studied. The results showed significant seasonal differences in water parameters and spatial differences in sediment nitrogen (P<0.001). No significant difference (P>0.05) was observed in α-diversity; the EC and SOEF-NH4+-N were important factors affecting the α-diversity of the water and sediment. Denitrifying bacteria mainly belonged to the phylum Proteobacteria and the genera Dechloromonas, Rhodocyclaceae, Pseudomonas, Rhodobacter, and Thauera. Principal coordinate analysis revealed that the community of denitrifying bacteria in the water and sediment exhibited significant spatial differences (P<0.001); keystone denitrifying bacteria in the water also exhibited significant spatial differences (P<0.001). RDA and RF analysis showed that the permanganate index and TP were the main environmental factors affecting the total and keystone denitrifying bacteria in the water; SOEF-NH4+-N, IEF-NH4+-N, and WAEF-NO3--N were the main environmental factors affecting the total and keystone denitrifying bacteria in the sediment. These findings could serve as a reference to understand the interaction mechanism between nitrogen and denitrification bacterial communities in landscape water.

[Structure of Aerobic Denitrification Bacterial Community in Response to Dissolved Organic Matter in Baiyangdian Lake During the Water Delivery Period].

Dissolved organic matter (DOM) plays an important role in the evolution of microbial communities. Meanwhile, ecological water delivery is an important feature of Baiyangdian Lake. To explore how the structure of the aerobic denitrification bacteria community responds to DOM during the water delivery period, the DOM components of water were examined and high-throughput sequencing of aerobic denitrification bacteria was performed. The results showed significant differences in DOM concentration in Baiyangdian Lake, with the estuary area exhibiting lower DOM concentrations. The water exhibited strong autogenous source, while DOM in the estuary area had a higher molecular weight and degree of humification. Three protein-like substances (C1, C2, and C4) and one humic-like substance (C3) were identified through PARAFAC. The protein-like substances accounted for the major proportion of DOM, which was consistent with the results of fluorescence regional integration (FRI). The genera of the water body were mainly in the Protebacterice phylum, including Cupriavidus, Aeromonas, Thauera, Shewanella, and Pseudomonas. Meanwhile, Cupriavidus, Thauera, Shewanella, Agrobacterium, and Pseudomonas were the main indicator species, according to random forest (RF) analysis. Through network analysis, 35 key nodes of the network were obtained, belonging to Thauera, Cupriavidus, and Unclassified_bacteria, respectively. Redundancy analysis (RDA) showed that a humic-like substance was the main environmental factor regulating the whole structure of the aerobic denitrification bacterial community, while protein-like substances played important roles in changes to the indicator species and key nodes of the community. Overall, protein-like substances could provide an important reference for selecting carbon sources during the screening of efficient and cold resistance aerobic denitrification bacteria that are adapted to actual water bodies.

Detection of Novel Spotted Fever Group Rickettsiae (Rickettsiales: Rickettsiaceae) in Ticks (Acari: Ixodidae) in Southwestern China.

Spotted fever group rickettsiae, mainly maintained and transmitted by ticks, are important etiological agents of (re)emerging zoonotic diseases worldwide. It is of great significance to investigate spotted fever group rickettsiae in ticks in different areas for the prevention and control of rickettsioses. In this study, a total of 305 ticks were collected from wild and domestic animals in Chongqing, Guizhou, Yunnan, and Guangxi provinces of southwestern China during 2017-2019 and examined for the presence of spotted fever group rickettsiae by PCR with primers targeting the partial gltA, ompA, rrs, and htrA genes. Results showed that two spotted fever group rickettsiae species, including the pathogenic Candidatus Rickettsia jingxinensis (Rickettsiales: Rickettsiaceae) and a potential novel species Rickettsia sp. sw (Rickettsiales: Rickettsiaceae), were identified. The Ca. R. jingxinensis sequences were recovered from Rhipicephalus microplus (Ixodida: Ixodidae) and Haemaphysalis longicornis (Ixodida: Ixodidae) ticks and phylogenetically clustered with previous Ca. R. jingxinensis, Ca. R. longicornii (Rickettsiales: Rickettsiaceae), and Rickettsia sp. XY118 (Rickettsiales: Rickettsiaceae) strains. Rickettsia sp. sw was detected in Amblyomma geoemydae (Ixodida: Ixodidae) and Rh. microplus. Interestingly, as far as we know, this was the first report of Rickettsia (Rickettsiales: Rickettsiaceae) in A. geoemydae. Phylogenetic analyses indicated that this potential novel species was closely related to R. aeschlimannii (Rickettsiales: Rickettsiaceae) with gltA and ompA genes and grouped in a cluster composed of R. montanensis (Rickettsiales: Rickettsiaceae), R. raoultii (Rickettsiales: Rickettsiaceae), R. aeschlimannii, R. massiliae (Rickettsiales: Rickettsiaceae), and R. rhipicephali (Rickettsiales: Rickettsiaceae) with htrA, while formed a separate clade with rrs. The pathogenicity of Rickettsia sp. sw should be further confirmed. These results expand the knowledge of the geographical distribution and vector distribution of spotted fever group rickettsiae in China and are useful for assessing the potential public health risk.

Magnetic Resonance Gd-RGD Imaging Study of Hepatocellular Carcinoma with High and Low Metastatic Potential before and after Human Bone Marrow-derived Mesenchymal Stem Cell Intervention.

BACKGROUND: Biotherapy based on human bone marrow-derived mesenchymal stem cells (BMSCs) is currently the focus of research, especially in the field of autologous stem cell transplantation. A novel type of metastasis-associated magnetic resonance (MR) molecular imaging probe was constructed, and the changes in metastasis and proliferation of hepatocellular carcinoma (HCC) before and after BMSC intervention were observed through MR imaging (MRI). METHODS: Metastasis-associated MR molecular imaging probe, integrin αvß3ligand cRGD-PEG-DGL-DTPA-Gd (Gd-RGD), were constructed. After human BMSC intervention was performed for 6 weeks, tumor weight inhibition rates were calculated, and the RGD molecular probe was imaged through MRI with molecular imaging agent Gd-DTPA as control. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in the MRI experiment were used as semi-quantitative indicators. Polymerase chain reaction method was performed to detect proliferation- and metastasis-associated indicators, transforming growth factor ß-1 (TGFß1), osteopontin (OPN), and integrin subunit αvand ß3. RESULTS: The highest tumor weight inhibition rates were observed 3 weeks after the BMSC transplantation. The MR Gd-RGD in the HCC tissues after the BMSC intervention showed less enhancement than Gd-DTPA. The Gd-DTPA MRI of control group had higher SNR and CNR than Gd-RGD MRI in the experimental groups (P < 0.05). For high metastatic potential hepatocellular carcinoma (MHCC97-H), significant differences were observed in the SNRs and CNRs of Gd-RGD MRI before and after the BMSC intervention (P < 0.05). For low metastatic potential hepatocellular carcinoma (MHCC97-L), the CNRs of Gd-RGD MRI were statistically different before and after BMSC intervention (P < 0.05). With regard to MHCC97-H, OPN, ß3, and TGFß1 expression significantly decreased after BMSC intervention (P < 0.05). In MHCC97-L and OPN, ß3, TGFß1, and αv expression after BMSC intervention decreased, and the difference was statistically significant (P < 0.05). CONCLUSIONS: The CNR index of MRI is a good indicator for distinguishing high- and low-metastatic potential HCC tissues. After BMSC transplantation of MRI through the two kinds of tracer, the SNR and CNR indexes can distinguish two kinds of high and low metastatic potential HCC tissues, and Gd-RGD imaging is more suitable in distinguishing the metastatic potential changes through BMSC intervention.

Evolution of the structural chemistry of vanadium organodiphosphonate networks and frameworks: structural consequences of fluoride incorporation in the development of stable phases with void channels.

Hydrothermal reactions of solutions containing a vanadate source, an organodiphosphonate, an organonitrogen component, and HF (V/P/O/F) yield a series of oxyfluorovanadium-diphosphonates with charge-compensation provided by organoammonium cations or hydronium cations. While V/P/O/F networks provide the recurrent structural motif, the linkage between the layers and the details of the polyhedral connectivities within the layers are quite distinct for the five structures of this study. [H2pip][V4F4O2(H2O)2{O3P(CH2)3PO3}2] (1) (pip = piperazine) is a conventional three-dimensional (3D) "pillared" layer structure, whose V/P/O/F networks are buttressed by the propylene chains of the diphosphonate ligands. In contrast, [H2en][V2O2F2(H2O)2{O3P(CH2)4PO3}] (2) and [H2en]2[V6F12(H2O)2{O3P(CH2)5PO3}2 {HO3P(CH2)5PO3H}] (3) are two-dimensional (2D) slablike structures constructed of pairs of V/P/O/F networks sandwiching the pillaring organic tethers of the diphosphonate ligands. Despite the common overall topology, the layer substructures are quite different: isolated {VO5F} octahedra in 2 and chains of corner-sharing {VO(3)F(3)} octahedra in 3. The 3D structure of [H2en]2[V7O6F4(H2O)2{O3P(CH2)2PO3}4].7H2O (4.7H2O) exhibits a layer substructure that contains the ethylene bridges of the diphosphonate ligands and are linked through corner-sharing octahedral {VO6} sites. The connectivity requirements provide large channels that enclose readily removed water of crystallization. The structure of [H3O][V3F2(H2O)2{O3P(CH2)2PO3}2].3.5H2O (5.3.5H2O) is also 3D. Because of the similiarity with 4.7H2O, it exhibits V/P/O/F layers that include the organic tethers of the diphosphonates and are linked through corner-sharing {VO6} octahedra. In contrast to the network substructure of 4.7H2O, which contains binuclear and trinuclear vanadium clusters, the layers of 5.3.5 H2O are constructed from chains of corner-sharing {VO4F2} octahedra. Thermal studies of the open framework materials 4 and 5 reveal that incorporation of fluoride into the inorganic substructures provides robust scaffoldings that retain their crystallinity to 450 degrees C and above. In the case of 4, dehydration does not change the powder X-ray diffraction pattern of the material, which remains substantially unchanged to 450 degrees C. In the case of 5, there are two dehydration steps, that is, the higher temperature process associated with loss of coordinated water. This second dehydration results in structural changes as monitored by powder X-ray diffraction, but this new phase is retained to ca. 450 degrees C. The materials of this study exhibit a range of reduced oxidation states: 1 is mixed valence V(IV)/V(III) while 2 and 4.7H(2)O are exclusively V(IV) and 3 and 5.3.5H2O are exclusively V(III). These oxidation states are reflected in the magnetic properties of the materials. The paramagnetism of 1 arises from the presence of V(III) and V(IV) sites and conforms to the Curie-Weiss law with C = 2.38 em K/(Oe mol) and = -66 K with mu(eff) (300 K) = 4.33 mu(B). Compounds 3-5 exhibit Curie-Weiss law dependence of magnetism on temperature with mu(eff) (300 K) = 5.45 mu(B) for 3 (six V(III) sites), mu(eff) = 4.60 mu(B) for 4 (seven V(IV) sites) and mu(eff) = 4.13 mu(B) for 5 (two V(III) sites). Compound 2 exhibits antiferromagnetic interactions, and the magnetism may be described in terms of the Heisenberg linear antiferromagnetic chain model for V(IV). The effective magnetic moment at 300 K is 2.77 mu(B) (two V(IV) sites).

Structural diversity of the oxovanadium organodiphosphonate system: a platform for the design of void channels.

The hydrothermal reactions of a vanadium source, an appropriate diphosphonate ligand, and water in the presence of HF provide a series of compounds with neutral V-P-O networks as the recurring structural motif. When the {O3P(CH2)(n)PO3}4- diphosphonate tether length n is 2-5, metal-oxide hybrids of type 1, [V2O2(H2O){O3P(CH2)(n)PO3}] x xH2O, are isolated. The type 1 oxides exhibit the prototypical three-dimensional (3-D) "pillared" layer architecture. When n is increased to 6-8, the two-dimensional (2-D) "pillared" slab structure of the type 2 oxides [V2O2(H2O)4{O3P(CH2)6PO3}] is encountered. Further lengthening of the spacer to n = 9 provides another 3-D structure, type 3, constructed from the condensation of pillared slabs to give V-P-O double layers as the network substructure. When organic cations are introduced to provide charge balance for anionic V-P-O networks, oxides of types 4-7 are observed. For spacer length n = 3, a range of organodiammonium cations are accommodated by the same 3-D "pillared" layer oxovanadium diphosphonate framework in the type 4 materials [H3N(CH2)(n)NH3][V4O4(OH)2 {O3P(CH)3PO3}2] x xH2O [n = 2, x = 6 (4a); n = 3, x = 3 (4b); n = 4, x = 2 (4c); n = 5, x = 1 (4d); n = 6, x = 0.5 (4e); n = 7, x = 0 (4f)] and [H3NR]y[V4O4(OH)2 {O3P(CH)3PO3}2] x xH2O [R = -CH2(NH3)CH2CH3, y = 1, x = 0 (4g); R = -CH3, n = 2, x = 3 (4h); R = -CH2CH3, y = 2, x = 1 (4i); R = -CH2CH2CH3, y = 2, x = 0 (4j); cation = [H2N(CH2CH3)2], y = 2, x = 0 (4k)]. These oxides exhibit two distinct interlamellar domains, one occupied by the cations and the second by water of crystallization. Furthermore, as the length of the cation increases, the organodiammonium component spills over into the hydrophilic domain to displace the water of crystallization. When the diphosphonate tether length is increased to n = 5, structure type 5, [H3N(CH2)2NH3][V4O4(OH)2(H2O){O3P(CH2)5PO3}2] x H2O, is obtained. This oxide possesses a 2-D "pillared" network or slab structure, similar in gross profile to that of type 2 oxides and with the cations occupying the interlamellar domain. In contrast, shortening the diphosphonate tether length to n = 2 results in the 3-D oxovanadium organophosphonate structure of the type 7 oxide [H3N(CH2)5NH3][V3O3{O3P(CH2)2PO3}2]. The ethylenediphosphonate ligand does not pillar V-P-O networks in this instance but rather chelates to a vanadium center in the construction of complex polyhedral connectivity of 7. Substitution of piperazinium cations for the simple alkyl chains of types 4, 5, and 7 provides the 2-D pillared layer structure of the type 6 oxides, [H2N(CH2CH2)NH2][V2O2{O3P(CH)(n)PO3H}2] [n = 2 (6a); n = 4 (6b); n = 6 (6c)]. The structural diversity of the system is reflected in the magnetic properties and thermal behavior of the oxides, which are also discussed.