Polymorphic Phase Control of RDX-Based Explosives

The polymorphic phase of 1,3,5-trinitro-1,3,5-triazine (RDX) was examined as a function of mass loading, solvent, and sample deposition technique. When RDX was deposited at a high mass loading, the vibrational modes in the obtained Raman spectra were indicative of concomitant polymorphism as both the α-RDX and β-RDX phases were present. At low mass loadings, only β-RDX was observed regardless of solvent when using the drop cast crystallization method. However, α-RDX (the thermodynamically stable polymorphic phase observed with visible quantities of the explosive) was observed when RDX deposits were dry transferred. Observation of α-RDX was independent of the initial mass loading or the initial deposition solvent when using the dry transfer methodology. These data indicate that the use of the dry transfer preparation method can be used to successfully prepare RDX-based test articles with the α-RDX phase regardless of the solvent used to initially dissolve the RDX, the initial deposition technique, or the mass loading.

Download Full-text

Low‐Mass Star Formation and the Initial Mass Function in IC 348

The Astrophysical Journal ◽

10.1086/306393 ◽

1998 ◽

Vol 508 (1) ◽

pp. 347-369 ◽

Cited By ~ 121

Author(s):

K. L. Luhman ◽

G. H. Rieke ◽

C. J. Lada ◽

E. A. Lada

Keyword(s):

Star Formation ◽

Mass Function ◽

Initial Mass Function ◽

Initial Mass ◽

Mass Star ◽

Low Mass

Download Full-text

High-Mass Loading Hierarchically Porous Activated Carbon Electrode for Pouch-Type Supercapacitors with Propylene Carbonate-Based Electrolyte

Nanomaterials ◽

10.3390/nano11030785 ◽

2021 ◽

Vol 11 (3) ◽

pp. 785

Author(s):

Tai-Feng Hung ◽

Tzu-Hsien Hsieh ◽

Feng-Shun Tseng ◽

Lu-Yu Wang ◽

Chang-Chung Yang ◽

...

Keyword(s):

Activated Carbon ◽

Propylene Carbonate ◽

Rational Design ◽

Rate Capability ◽

High Mass ◽

Electrochemical Performances ◽

Mass Loading ◽

Hierarchically Porous ◽

Symmetric Supercapacitor ◽

Porous Activated Carbon

Rational design and development of the electrodes with high-mass loading yet maintaining the excellent electrochemical properties are significant for a variety of electrochemical energy storage applications. In comparison with the slurry-casted electrode, herein, a hierarchically porous activated carbon (HPAC) electrode with higher mass loading (8.3 ± 0.2 mg/cm2) is successfully prepared. The pouch-type symmetric device (1 cell) with the propylene carbonate-based electrolyte shows the rate capability (7.1 F at 1 mA/cm2 and 4.8 F at 10 mA/cm2) and the cycling stability (83% at 12,000 cycles). On the other hand, an initial discharge capacitance of 32.4 F and the capacitance retention of 96% after 30,000 cycles are delivered from a pouch-type symmetric supercapacitor (five cells). The corresponding electrochemical performances are attributed to the fascinating properties of the HPAC and the synergistic features of the resulting electrode.

Download Full-text

Phonons in Short-Period GaN/AlN Superlattices: Group-Theoretical Analysis, Ab initio Calculations, and Raman Spectra

Nanomaterials ◽

10.3390/nano11020286 ◽

2021 ◽

Vol 11 (2) ◽

pp. 286

Author(s):

Valery Davydov ◽

Evgenii Roginskii ◽

Yuri Kitaev ◽

Alexander Smirnov ◽

Ilya Eliseyev ◽

...

Keyword(s):

Theoretical Analysis ◽

Ab Initio Calculations ◽

Ab Initio ◽

Raman Spectra ◽

Density Functional ◽

Structural Characteristics ◽

Vibrational Modes ◽

Phonon Modes ◽

Short Period ◽

Group Theoretical Analysis

We report the results of experimental and theoretical studies of phonon modes in GaN/AlN superlattices (SLs) with a period of several atomic layers, grown by submonolayer digital plasma-assisted molecular-beam epitaxy, which have a great potential for use in quantum and stress engineering. Using detailed group-theoretical analysis, the genesis of the SL vibrational modes from the modes of bulk AlN and GaN crystals is established. Ab initio calculations in the framework of the density functional theory, aimed at studying the phonon states, are performed for SLs with both equal and unequal layer thicknesses. The frequencies of the vibrational modes are calculated, and atomic displacement patterns are obtained. Raman spectra are calculated and compared with the experimental ones. The results of the ab initio calculations are in good agreement with the experimental Raman spectra and the results of the group-theoretical analysis. As a result of comprehensive studies, the correlations between the parameters of acoustic and optical phonons and the structure of SLs are obtained. This opens up new possibilities for the analysis of the structural characteristics of short-period GaN/AlN SLs using Raman spectroscopy. The results obtained can be used to optimize the growth technologies aimed to form structurally perfect short-period GaN/AlN SLs.

Download Full-text

Carbon-coated TiNb2O7 nanosheet arrays as self-supported high mass-loading anode for flexible Li-ion battery

Chemical Communications ◽

10.1039/d0cc08251a ◽

2021 ◽

Author(s):

Jinquan Zhou ◽

Haoyang Dong ◽

Yao Chen ◽

yihua Ye ◽

Liang Xiao ◽

...

Keyword(s):

Diffusion Length ◽

High Mass ◽

Carbon Cloth ◽

Mass Loading ◽

Solvothermal Process ◽

Li Ion Battery ◽

Nanosheet Arrays ◽

Carbon Coated ◽

Li Ion ◽

First Time

TiNb2O7 anode constructed with carbon-coated nanosheet arrays on carbon cloth is prepared by a facile solvothermal process and post carbon-coating for the first time. With nanosized diffusion-length and reduced polarization...

Download Full-text

On the emergent system mass function: the contest between accretion and fragmentation

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3176 ◽

2020 ◽

Vol 500 (2) ◽

pp. 1697-1707

Author(s):

Paul C Clark ◽

Anthony P Whitworth

Keyword(s):

Star Formation ◽

Standard Deviation ◽

Mass Distribution ◽

Power Law ◽

Accretion Rate ◽

Mass Function ◽

High Mass ◽

New Model ◽

System Formation ◽

Low Mass

ABSTRACT We propose a new model for the evolution of a star cluster’s system mass function (SMF). The model involves both turbulent fragmentation and competitive accretion. Turbulent fragmentation creates low-mass seed proto-systems (i.e. single and multiple protostars). Some of these low-mass seed proto-systems then grow by competitive accretion to produce the high-mass power-law tail of the SMF. Turbulent fragmentation is relatively inefficient, in the sense that the creation of low-mass seed proto-systems only consumes a fraction, ${\sim }23{{\ \rm per\ cent}}$ (at most ${\sim }50{{\ \rm per\ cent}}$), of the mass available for star formation. The remaining mass is consumed by competitive accretion. Provided the accretion rate on to a proto-system is approximately proportional to its mass (dm/dt ∝ m), the SMF develops a power-law tail at high masses with the Salpeter slope (∼−2.3). If the rate of supply of mass accelerates, the rate of proto-system formation also accelerates, as appears to be observed in many clusters. However, even if the rate of supply of mass decreases, or ceases and then resumes, the SMF evolves homologously, retaining the same overall shape, and the high-mass power-law tail simply extends to ever higher masses until the supply of gas runs out completely. The Chabrier SMF can be reproduced very accurately if the seed proto-systems have an approximately lognormal mass distribution with median mass ${\sim } 0.11 \, {\rm M}_{\odot }$ and logarithmic standard deviation $\sigma _{\log _{10}({M/M}_\odot)}\sim 0.47$).

Download Full-text

Boosting Rate Performance of Li–S Batteries under High-Mass-Loading Sulfur based on Hierarchical NCNT@Co-CoP Nanowires Integrated Electrode

Journal of Materials Chemistry A ◽

10.1039/d1ta00959a ◽

2021 ◽

Author(s):

Jianbo Li ◽

Wenfu Xie ◽

Shimeng Zhang ◽

Simin Xu ◽

Mingfei Shao

Keyword(s):

Storage Systems ◽

High Mass ◽

Mass Loading ◽

Rate Performance ◽

Next Generation ◽

Practical Application ◽

Lithium Sulfur Batteries ◽

Lithium Sulfur

Lithium−sulfur batteries (Li–S) has been gradual becoming one of the most promising next-generation storage systems, but its practical application is still limited by the extremely low S loading as well...

Download Full-text

High mass-loading NiCo-LDH nanosheet arrays grown on carbon cloth by electrodeposition for excellent electrochemical energy storage

Nano Energy ◽

10.1016/j.nanoen.2021.106079 ◽

2021 ◽

pp. 106079

Author(s):

Xiangyu Han ◽

Jien Li ◽

Junlin Lu ◽

Shuang Luo ◽

Jing Wan ◽

...

Keyword(s):

Energy Storage ◽

Electrochemical Energy Storage ◽

High Mass ◽

Carbon Cloth ◽

Mass Loading ◽

Nanosheet Arrays ◽

Electrochemical Energy

Download Full-text

NIR-responsive MXene nanobelts for wound healing

NPG Asia Materials ◽

10.1038/s41427-021-00289-w ◽

2021 ◽

Vol 13 (1) ◽

Author(s):

Lin Jin ◽

Xiaoqing Guo ◽

Di Gao ◽

Cui Wu ◽

Bin Hu ◽

...

Keyword(s):

Wound Healing ◽

Vitamin E ◽

Surface Area ◽

Near Infrared ◽

Coating Layer ◽

High Surface ◽

High Surface Area ◽

High Mass ◽

Polymeric Coating ◽

Mass Loading

AbstractEffectively achieving wound healing is a great challenge. Herein, we facilely prepared temperature-responsive MXene nanobelt fibers (T-RMFs) carrying vitamin E with a controllable release ability for wound healing. These T-RMFs were composed of MXene nanosheets spread along polyacrylonitrile and polyvinylpyrrolidone composite nanobelts together with a thermosensitive PAAV- coating layer. The high mass loading and high surface area of the MXene nanosheets endow the T-RMFs with excellent photothermal properties. The temperature could be easily controlled by near-infrared (NIR) irradiation exposure, and then the thermoresponsive polymeric coating layer relaxed the interface to dissolve vitamin E and promote vitamin E release. The T-RMFs demonstrated excellent biocompatibility and wound-healing functions in cellular and animal tests. The facile method, high mass loading, high surface area, excellent wound-healing functions, interesting nanosheet/nanobelt structure, mass production potential, and NIR responsive properties of these T-RMFs indicate the great potential of our nanobelts for wound healing, tissue engineering, and much broader application areas. This facile nanosheet/nanobelt preparation strategy paves a new way for nanomaterial fabrication and applications.

Download Full-text

Electrode Design for MnO2-Based Aqueous Electrochemical Capacitors: Influence of Porosity and Mass Loading

Materials ◽

10.3390/ma14112990 ◽

2021 ◽

Vol 14 (11) ◽

pp. 2990

Author(s):

Camille Douard ◽

Laurence Athouël ◽

David Brown ◽

Olivier Crosnier ◽

Guillaume Rebmann ◽

...

Keyword(s):

Electrode Materials ◽

Large Mass ◽

Time Response ◽

High Mass ◽

Mass Loading ◽

Electrical Behavior ◽

Power Battery ◽

Porosity Effect ◽

Fabrication Parameters ◽

Crucial Parameter

The purpose of this study is to highlight the influence of some fabrication parameters, such as mass loading and porosity, which are not really elucidated and standardized during the realization of electrodes for supercapacitors, especially when using metal oxides as electrode materials. Electrode calendering, as one stage during the fabrication of electrodes, was carried out step-by-step on manganese dioxide electrodes to study the decreasing porosity effect on the electrochemical performance of a MnO2 symmetric device. One other crucial parameter, the mass loading, which has to be understood and well used for realistic supercapacitors, was investigated concurrently. Gravimetric, areal and volumetric capacitances are highlighted, varying the porosity for low-, medium- and large-mass loading. Low-loading leads to the best specific capacitances but is not credible for realistic supercapacitors, except for microdevices. Down 50% porosities after calendering, capacitances are increased and become stable faster, suggesting a faster wettability of the dense electrodes by the electrolyte, especially for high-mass loading. EIS experiments performed on electrodes without and with calendering lead to a significant decrease of the device’s time response, especially at high loading. A high-mass loading device seems to work as a power battery, whereas electrode calendaring, which allows decreasing the time response, leads to an electrical behavior closer to that expected for a supercapacitor.

Download Full-text