Shock Initiation Experiments with Modeling on a DNAN Based MeltCast Insensitive Explosive

2,4-dinitroanisole(DNAN)is a good replacement for 2,4,6-trinitrotoluene(TNT)in melt-cast explosives due to its superior insensitivity.With the increasing use of DNAN-based melt-cast explosives,the prediction of reaction violence and hazard assessment of the explosives subjected to shock is of great significance.This study investigated the shock initiation characteristics for a DNAN-based melt-cast explosive,DHFA,using the one-dimensional Lagrangian apparatus.The embedded manganin gauges in the apparatus record the pressure histories at four Lagrangian positions and show that shock-todetonation transition in DHFA needs a high input shock pressure.The experimental data are analyzed to calibrate the Ignition and Growth model.The calibration is performed using an objective function based on both pressure history and the arrival time of shock.Good agreement between experimental and calculated pressure histories indicates the high accuracy of the calibrated parameters with the optimization method.

1550nm Polarization-Insensitive Semiconductor Optical Amplifier Based on AlGaInAs-InP

Polarization insensitive AlGaInAs InP semiconductor optical amplifier is realized at a wavelength of 1550nm.The active layer consists of three tensile strained wells with strain 0 40%.The amplifiers are fabricated to ridge waveguide structure with 7° tilted cavity.The two facets are coated with two layers of anti reflection Ti 3O 5/Al 2O 3 films.Residual facet reflectivity is found to be less than 0 03%.The semiconductor optical amplifer exhibits 20dB of signal gain and 7 2dBm of saturation output power with an excellent polarization insensitivity (less than 0 8dB) at 200mA and 1540nm window.

Insensitive energetic microspheres DAAF/RDX fabricated by facile molecular self-assembly

Insensitive energetic materials are promising in the defense weapons field.However,energetic materials still suffer from great challenges and the concern about their safety limits their utilization.In this work,insensitive energetic explosive 3,30-diamino-4,40-azoxyfurazan/hexahydro-1,3,5-trinitro-1,3,5-triazine(DAAF/RDX)microspheres were fabricated by self-assembly method.Rod-like DAAF/RDX was prepared by mechanical ball milling for comparison.DAAF/RDX composites with different mass ratios(90:10,80:20,and 70:30)were obtained.The morphologies and structures of as-obtained DAAF/RDX composites were characterized by scanning electron microscopy(SEM),powder x-ray diffraction(PXRD)and fourier transform infrared spectroscopy(FT-IR).The results showed that DAAF/RDX microspheres exhibited regular shaped microspheres with sizes from 0.5 to 1.2 mm.There was no crystal transition during the modification process.The thermal properties of as-obtained materials were then evaluated by differential scanning calorimetry(DSC)and materials studio software.DAAF/RDX microspheres showed an advanced decomposition peak temperature compared with rod-like DAAF/RDX.The binding energy and peak temperature values at zeroβ_(i)(T_(P0))of DAAF/RDX(90:10)increased by 36.77 kJ/mol,1.6℃,and 58.11 kJ/mol,12.3℃compared to DAAF/RDX(80:20)and DAAF/RDX(70:30),indicating the better thermal stability of DAAF/RDX(90:10).The characteristic drop height(H_(50))of DAAF/RDX(higher than 100 cm)composites was higher than that of raw RDX(25 cm),suggesting significant improvements in mechanical safety.The preparation of DAAF/RDX microspheres is promising for the desensitization of RDX and useful for the formation of other materials and future wide applications.

QTL Identification of the Insensitive Response to Photoperiod and Temperature in Soybean by Association Mapping

The insensitive response to photoperiod and temperature is an important quantitative trait for soybean in wide adaptation breeding. The natural variation in response to photoperiod and temperature was detected using 275 accessions of soybean [Glycine max （L.） Merrill] from China. Genome-wide association mapping, based on population structure analysis, was carried out using 118 SSR markers by the TASSEL GLM （general linear model） program. Nine SSR markers （P〈0.01） were associated with the value of the response to photoperiod and temperature （VRPT） caused by days to flowering （DF）, among which, Satt308 （LG M）, Sattl50 （LG M） and Satt440 （LG l）, were identified in both 2006 and 2007. Twelve SSR markers （P〈0.01） were associated with VRPT caused by days to maturity （DM）, among which three markers, Satt387 （LG N）, Satt307 （LG C2） and AW310961 （LG J）, were detected in both 2006 and 2007. In addition, a total of 20 elite alleles were screened out over 2006 and 2007 for being associated with an insensitive response to photoperiod and temperature （IRPT） caused by DF and a total of seven different elite alleles were screened out for being associated with IRPT caused by DM. Among these elite alleles, five alleles, Satt150-244, Satt308-164, Satt308-206, Satt440-176, and Satt440-206, were associated with IRPT caused by DF and were identified in both years, but only one allele, Satt307-170, was identified as being associated with an IRPT caused by DM. Based on these elite alleles, a set of typical accessions were screened out. The result about the genetic basis of IRPT is meaningful for soybean wide adaption breeding.

Insensitive high explosives:Ⅳ. Nitroguanidine-Initiation & detonation

This paper reviews the detonative properties of low bulk density(LBD),high bulk density(HBD)Nitroguanidine(NGu)(1),CAS-No:[556-88-7]and 82 explosive formulations based on NGu reported in the public domain.To rank the performance of those formulations they are compared with 15 reference compositions containing both standard high explosives such as octogen(HMX)(2),hexogen(RDX)(3),pentaerythritol tetranitrate(PETN)(4),2,4,6-trinitrotoluene(TNT)(5)as well as insensitive high explosives such as 3-nitro-1,2,4-triazolone(NTO)(6),1,3,5-triamino-2,4,6-trinitrobenzene(TATB)(7),1,1-diamino-2,2-dinitroethylene(FOX-7)(8)and N-Guanylurea dinitramide(FOX 12)(9).NGu based formulations are superior to those based on FOX-12 or TATB and are a close match with FOX-7 based explosives,the latter just having higher Gurney Energies(-10%)and slightly higher detonation pressure(+2%).NGu based explosives even reach up to 78% of the detonation pressure,82% Gurney energy and up to 95% of detonation velocity of HMX.LBD-NGu dissolves in many melt cast eutectics forming dense charges thereby eliminating the need for costly High Bulk Density NGu.Nitroguanidine based formulations are at the rock bottom of sensitiveness among all the above-mentioned explosives which contributes to the safety of these formulations.The review gives 132 references to the public domain.For a review on the synthesis spectroscopy and sensitiveness of Nitroguanidine see Ref.[1].

Facile Preparation of Polypeptides:Moisture Insensitive and Superfast Ring Opening Polymerization of N-Carboxyanhydrides

(a)NCA polymerization initiated by LiHMDS or other initiators in THF,initiator i)n-hexylamine,ii)HMDS,iii)bipyNi(COD);(b)LiHMDS-initiated open vessel polymerization of BLGNCA at 26 mg and 2 g scale;(c)GPC traces of poly-BLG at variable DP;(d)Reaction rates of LiHMDS and hexylamine initiated BLGNCA polymerization in THF with NCA:initiator ratio of 100∶1 and initial NCA concentration at 0.2 mol/L;(e)CD spectra of poly-BLG at variable DP prepared from LiHMDS-initiated NCA polymerization.

Polarization Insensitive Broadband Zero Indexed Nano-Meta Absorber for Optical Region Applications

Broadband response metamaterial absorber(MMA)remains a challenge among researchers.A nanostructured new zero-indexed metamaterial(ZIM)absorber is presented in this study,constructed with a hexagonal shape resonator for optical region applications.The design consists of a resonator and dielectric layers made with tungsten and quartz(Fused).The proposed absorbent exhibits average absorption of more than 0.8972(89.72%)within the visible wavelength of 450–600 nm and nearly perfect absorption of 0.99(99%)at 461.61 nm.Based on computational analysis,the proposed absorber can be characterized as ZIM.The developments of ZIM absorbers have demonstrated plasmonic resonance characteristics and a perfect impedance match.The incidence obliquity in typically the range of 0◦–90◦both in TE and TM mode with maximum absorbance is more than 0.8972(∼89.72%),and up to 45◦angular stability is suitable for solar cell applications,like exploiting solar energy.The proposed structure prototype is designed and simulated by studying microwave technology numerical computer simulation(CST)tools.The finite integration technique(FIT)based simulator CST and finite element method(FEM)based simulator HFSS also helps validate the numerical data of the proposed ZIM absorber.The proposed MMA design is appropriate for substantial absorption,wide-angle stability,absolute invisible layers,magnetic resonance imaging(MRI),color images,and thermal imaging applications.

Graphene-Based Tunable Polarization Insensitive Dual-Band Metamaterial Absorber at Mid-Infrared Frequencies

A graphene-based tunable dual-band metamaterial absorber which is polarization insensitive is numerically pro- posed at mid-infrared frequencies. In numerical simulation the metamaterial absorber exhibits two absorption peaks at the resonance wavelengths of 6.246 μm and 6.837μm when the Fermi level of graphene is fixed at 0. 6 eV. Absorption spectra at different Fermi levels of graphene are displayed and tuning functions are discussed in detail. Both the resonance wavelengths of the absorber blue shift with the increase in Fermi level of graphene. Moreover, the surface current distributions on the gold resonator and ground plane at the two resonance wavelengths are simulated to deeply understand the physical mechanism of resonance absorption.

The Confinement Effect of Inert Materials on the Detonation of Insensitive High Explosives

The paper aims to theoretically and numerically investigate the confinement effect of inert materials on the detonation of insensitive high explosives. An improved shock polar theory based on the Zeldovich-von Neumann-Döring model of explosive detonation is established and can fully categorize the confinement interactions between insensitive high explosive and inert materials into six types for the inert materials with smaller sonic velocities than the Chapman-Jouguet velocity of explosive detonation. To confirm the theoretical categorization and obtain the flow details, a second-order, cell-centered Lagrangian hydrodynamic method based on the characteristic theory of the two-dimensional first-order hyperbolic partial differential equations with Ignition-Growth chemistry reaction law is proposed and can exactly numerically simulate the confinement interactions. The numerical result confirms the theoretical categorization and can further merge six types of interaction styles into five types for the inert materials with smaller sonic velocity, moreover, the numerical method can give a new type of interaction style existing a precursor wave in the confining inert material with a larger sonic velocity than the Chapman-Jouguet velocity of explosive detonation, in which a shock polar theory is invalid. The numerical method can also give the effect of inert materials on the edge angles of detonation wave front.

Detection of Graphene Cracks By Electromagnetic Induction,Insensitive to Doping Level

Detection of cracks is a great concern in production and operation processes of graphene based devices to ensure uniform quality.Here,we show a detection method for graphene cracks by electromagnetic induction.The time varying magnetic field leads to induced voltage signals on graphene,and the signals are detected by a voltmeter.The measured level of induced voltage is correlated with the number of cracks in graphene positively.The correlation is attributed to the increasing inductive characteristic of defective graphene,and it is verified by electromagnetic simulation and radio frequency analysis.Furthermore,we demonstrate that the induced voltage signal is insensitive to the doping level of graphene.Our work can potentially lead to the development of a high-throughput and reliable crack inspection technique for mass production of graphene applications.

Theoretical design of new bridge-ring insensitive high energy compounds by selected normal Diels-Alder reactions between NH_(2)-substituted oxazoles and NO_(2)/NF_(2)/NHNO_(2)-substituted ethylenes/acetylenes

In this work,NH_(2)-substituted oxazoles and NO_(2)/NF_(2)/NHNO_(2)-substituted ethylenes/acetylenes were designed and used as dienes and dienophiles,respectively,in order to develop new bridge-ring insensitive high energy compounds through the Diels-Alder reaction between them.The reaction type,reaction feasibility and performance of reaction products were investigated in detail theoretically.The results showed that dienes most possibly react with dienophiles through the HOMO-diene controlled normal Diels-Alder reaction at relatively low energy barrier.Tetranitroethylene could react with the designed dienes much more easily than other dienophiles,and was employed to further design 29 new bridge-ring energetic compounds.Due to high heat of formation,density and oxygen balance,all designed bridge-ring energetic compounds have outstanding detonation performance,16 of them have higher energy than HMX(1,3,5,7-tetranitro-1,3,5,7-tetrazocine)and 2 others even possess comparative energy with the representative of high energy compounds CL-20(2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane).The predicted average h50 value of these bridge-ring energetic compounds is 83 cm,showing their low impact sensitivity.The NH2 groups could obviously impel the proceeding of Diels-Alder reactions,but would slightly decrease the energy and sensitivity performance.In all,the new designed bridge-ring compounds have both high energy and low sensitivity,and may be produced through Diels-Alder reactions at relatively low energy barrier.This paper may be helpful for the theoretical design and experiment synthesis of new advanced insensitive high energy compounds.

A proposal for the generation of optical frequency comb in temperature insensitive microcavity

We numerically simulate the generation of an optical frequency comb（OFC） in a microring based on the traditional Si_3N_4 strip waveguide and a temperature compensated slot waveguide.The results show that OFCs are susceptible to temperature with strip waveguide while they can keep stable when temperature changes 10 Kin either low-Q（10-5） or highQ（10-6） microcavity with the well-designed slot waveguide,which has great superiority in practical applications where the temperature drift of the cavity due to the intense pump or surrounding change is unavoidable.

Angular insensitive nonreciprocal ultrawide band absorption in plasma-embedded photonic crystals designed with improved particle swarm optimization algorithm

Using an improved particle swarm optimization algorithm(IPSO)to drive a transfer matrix method,a nonreciprocal absorber with an ultrawide absorption bandwidth and angular insensitivity is realized in plasma-embedded photonic crystals arranged in a structure composed of periodic and quasi-periodic sequences on a normalized scale.The effective dielectric function,which determines the absorption of the plasma,is subject to the basic parameters of the plasma,causing the absorption of the proposed absorber to be easily modulated by these parameters.Compared with other quasi-periodic sequences,the Octonacci sequence is superior both in relative bandwidth and absolute bandwidth.Under further optimization using IPSO with 14 parameters set to be optimized,the absorption characteristics of the proposed structure with different numbers of layers of the smallest structure unit N are shown and discussed.IPSO is also used to address angular insensitive nonreciprocal ultrawide bandwidth absorption,and the optimized result shows excellent unidirectional absorbability and angular insensitivity of the proposed structure.The impacts of the sequence number of quasi-periodic sequence M and collision frequency of plasma1ν1 to absorption in the angle domain and frequency domain are investigated.Additionally,the impedance match theory and the interference field theory are introduced to express the findings of the algorithm.

Differentiated design strategies toward broadband achromatic and polarizationinsensitive metalenses

Metasurfaces have emerged as a flexible platform for shaping the electromagnetic field via the tailoring phase,amplitude,and polarization at will.However,the chromatic aberration inherited from building blocks’diffractive nature plagues them when used in many practical applications.Current solutions for eliminating chromatic aberration usually rely on searching through many meta-atoms to seek designs that satisfy both phase and phase dispersion preconditions,inevitably leading to intensive design efforts.Moreover,most schemes are commonly valid for incidence with a specific spin state.Here,inspired by the Rayleigh criterion for spot resolution,we present a design principle for broadband achromatic and polarization-insensitive metalenses using two sets of anisotropic nanofins based on phase change material Ge2Sb2Se4Te1.By limiting the rotation angles of all nanofins to either 0 deg or 90 deg,the metalens with a suitable numerical aperture constructed by this fashion allows for achromatic and polarization-insensitive performance across the wavelength range of 4–5μm,while maintaining high focusing efficiency and diffraction-limited performance.We also demonstrate the versatility of our approach by successfully implementing the generation of broadband achromatic and polarization-insensitive focusing optical vortex.This work represents a major advance in achromatic metalenses and may find more applications in compact and chip-scale devices.

Reflection behavior of insensitive explosive detonation propagating around a cylinder

Insensitive explosive detonation has wide applications in compressing and driving inert materials,and thereby the interaction between detonation and inert materials has received more attention.In this paper,a two-dimensional numerical simulation based on the Euler multiphase flow framework is used to investigate the reflection behavior of the insensitive explosive detonation propagating around a cylinder.The results show that there is a critical incident angle,defined as transition angle for detonation propagating around the cylinder,below which the regular reflection(RR)on the cylinder surface is observed.When the incident angle is greater than the transition angle,RR changes to Mach reflection.This transition angle is larger than that obtained by polar curve theory and the change of incident angle is used to interpret above phenomenon.In addition,the influence of cylindrical radius and detonation reaction zone width on the reflection behavior is examined.As the cylindrical radius increases,the height of Mach stem increases while the transition angle decreases and gradually approaches the value in pole curve theory.Von Neumann reflection is observed when the reaction zone width is relatively small.This is because the energy release rate in the reaction zone is high for small reaction zone width,resulting in the formation of a series of compression waves near the cylindrical interface.

Polarization-insensitive optical coherence tomography using polarization maintaining fiber with a simple optical configuration

Compensation of polarization-variance-related artifacts is required to steadily obtain high-quality optical coherence tomography(OCT)images at various experimental conditions.Since most OCT systems utilize optical fiber to transfer the light easily and a polarized light source,the polarization state is arbitrarily changed in every different condition.In this study,we proposed polarization-maintaining-fiber-based polarization-insensitive OCT(PM-PI-OCT)with a simple optical configuration and a simple compensation process.The proposed PMPI-OCT is not only theoretically proved by mathematical derivations but also evaluated by quantitative analysis of various fiber twisting angles.Moreover,the applicability and robustness of the proposed PM-PI-OCT were proved by human retina imaging using the customized handheld probe.Our proposed polarization-insensitive OCT requires no pre-calibration,no post-processing procedure,and no computational load for implementation and is able to be applied to universal fiber-based OCT systems.We believe that our simple and robust polarization-insensitive OCT system is able to be applied to various existing OCT setups for polarization state variance compensation with high versatility and applicability.

Ligand Perception,Activation,and Early Signaling of Plant Steroid Receptor Brassinosteroid Insensitive 1

Leucine-rich repeat receptor-like kinases （LRR-RLKs） belong to a large group of cell surface proteins involved in many aspects of plant development and environmental responses in both monocots and dicots. Brassinosteroid insensitive 1 （BRI1）, a member of the LRR X subfamily, was first identified through several forward genetic screenings for mutants insensitive to brassinosteroids （BRs）, which are a class of plant-specific steroid hormones. Since its identification, BRI1 and its homologs had been proved as receptors perceiving BRs and initiating BR signaling. The co-receptor BRIl-associated kinase 1 and its homologs, and other BRI1 interacting proteins such as its inhibitor BRI1 kinase inhibitor I （BKI1） were identified by genetic andbiochemical approaches. The detailed mechanisms of BR perception by BRI1 and the activation of BRI1 receptor complex have also been elucidated. Moreover, several mechanisms for termination of the activated BRI1 signaling were also discovered. In this review, we will focus on the recent advances on the mechanism of BRI1 phosphorylation and activation, the regulation of its receptor complex, the structure basis of BRI1 ectodomain and BR recognition, its direct substrates, and the termination of the activated BRI1 receptor complex.

A process-insensitive thermal protection circuit

A novel process-insensitive thermal protection structure has been developed.This circuit contains several sub-circuits such as band-gap reference,reference output buffer,resistance voltage divider branch,and hysteresis circuit.By using reference buffer,the precise reference voltage from band-gap reference is delivered to resistance voltage divider branch and is divided precisely.Then the threshold temperatures of this protection circuit can be set by this precise voltage,unaffected by process variation and mismatch.A hysteresis circuit is also used here to prevent thermal oscillation.This circuit is fabricated in TSMC 0.18μm CMOS technology,and occupies about 3×10;μm;chip area.

High energy and insensitive explosives based on energetic porous aromatic frameworks

The design and synthesis of energetic materials with a compatibility of high energy and insensitivity have always been the research fronts in military and civilian fields.Considering excellent performances of porous organic frameworks and the lack of research in the field of energetic materials,in this study,a new concept named energetic porous aromatic frameworks(EPAFs)is proposed.The strategy of coating high energy explosives such as 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(CL-20)and 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX)in the EPAFs by wet-infiltration method has successfully realized the assembly of target energetic composite materials.The results show that the 75 wt.%CL-20@EPAF-1 possesses the safer impact sensitivity of 31.4 J than that of CL-20(4.0 J).Notably,for 75 wt.%CL-20@EPAF-1,in addition to the superior detonation performances of the detonation velocity(8,761 m·s^(-1))and detonation pressure(31.27 GPa),the synergistic effect of the nitrogen-rich EPAFs and the nitramines high energy explosives results in a higher heat of detonation that surpasses the most of pristine high explosives and reported novel energetic materials.In prospect,energetic porous aromatic frameworks could be a promising and inspiring strategy to build high energy insensitive energetic materials.

Polarization-insensitive interferometer based on a hybrid integrated planar light-wave circuit

Interferometers are essential elements in classical and quantum optical systems.The strictly required stability when extracting the phase of photons is vulnerable to polarization variation and phase shift induced by environment disturbance.Here,we implement polarization-insensitive interferometers by combining silica planar light-wave circuit chips and Faraday rotator mirrors.Two asymmetric interferometers with temperature controllers are connected in series to evaluate the single-photon interference.Average interference visibility over 12 h is above 99%,and the variations are less than 0.5%,even with active random polarization disturbance.The experiment results verify that the hybrid chip is available for high-demand applications like quantum key distribution and entanglement measurement.