Comparative investigations of ternary thermite Al/Fe_(2)O_(3)/CuO and Al/Fe_(2)O_(3)/Bi_(2)O_(3) from pyrolytic,kinetics and combustion behaviors

To develop new energy enhancement energetic materials with great combustion performance and thermal stability,two kinds of ternary thermite,Al/Fe_(2)O_(3)/CuO and Al/Fe_(2)O_(3)/Bi_(2)O_(3),were prepared and analyzed via mechanical ball milling.The samples were characterized by SEM,XRD,TG-DSC,constant volume and constant pressure combustion experiments.The first exothermic peaks of Al/Fe_(2)O_(3)/CuO and Al/Fe_(2)O_(3)/Bi_(2)O_(3) appear at 579°C and 564.5°C,respectively.The corresponding activation energies are similar.The corresponding mechanism functions are set as G(a) = [-ln(1-a)]^(3/4) and G(a) =[-ln(1-a)]2/3,respectively,which belong to the Avrami-Erofeev equation.Al/Fe_(2)O_(3)/CuO has better thermal safety.For small dose samples,its critical temperature of thermal explosion is 121.05°C higher than that of Al/Fe_(2)O_(3)/Bi_(2)O_(3).During combustion,the flame of Al/Fe_(2)O_(3)/CuO is spherical,and the main products are FeAl_(2)O_(4) and Cu.The flame of Al/Fe_(2)O_(3)/Bi_(2)O_(3)is jet-like,and the main products are Al_(2)O_(3),Bi and Fe.Al/Fe_(2)O_(3)/Bi_(2)O_(3)has better ignition and gas production performance.Its average ignition energy is 4.2 J lower than that of Al/Fe_(2)O_(3)/CuO.Its average step-up rate is 28.29 MPa/s,which is much higher than 6.84 MPa/s of Al/Fe_(2)O_(3)/CuO.This paper provides a reference for studying the thermal safety and combustion performance of ternary thermite.

Correlation between optical coherence tomography, multifocal electroretinogram findings and visual acuity in diabetic macular edema

AIM:To analyze the correlation between macular morphology and function in eyes with diabetic macular edema(DME).METHODS:Fifty-five eyes with different visual acuity(VA)of 32 patients who suffered from DME were analyzed using multifocal electroretinography(mfERG)and optical coherence tomography(OCT).The parameters of mfERG including implicit times and response amplitude were compared to those of 50 normal eyes of 36 age-matched subjects.Correlation analysis was performed between VA,the parameters of mfERG including implicit times and response amplitude,and the central macular thickness(CMT).RESULTS:The amplitude of N1 and P1 were significantly decreased and their latency were significantly increased in five ring regions of the retina in patients with DME.There was statistically significant correlation between logMAR BCVA and P1 amplitude densities in rings 1-4(r=-0.306,-0.536,-0.470,-0.362;P=0.023,<0.01,<0.01,0.007 respectively),N1 amplitude in ring 2 and ring 3(r=-0.035,-0.286;P=0.019,0.034 respectively).There was poor correlation between the CMT and best-corrected visual acuity(BCVA;r=0.288,P=0.033),but there was no significant correlation between CMT and amplitude or implicit time of N1 and P1(P>0.05)in the central macular ring.Multiple stepwise regression analysis showed that P1 amplitude density in ring 2 was the only contributor to the VA.CONCLUSION:It seems to be more appropriate of combining use of mfERG with OCT for the evaluation of macular function in eyes with DME.

Thermal and combustion behavior of Al-MnO_(2) nanothermite with poly(vinylidene fluoride-co-hexafluoropropylene) energetic binder

Fluoropolymers get increasing attention in energetic materials application due to the high fluorine content.To explore the effect of poly(vinylidene fluoride-co-hexafluoropropylene)(P(VDF-HFP))on Al/MnO_(2) nanothermite,the samples with different contents are prepared and characterized by SEM,TGDSC,XRD,and their ignition and combustion behavior are tested and recorded.The results show that P(VDF-HFP)as an energetic binder can combine the nanothermite components together,even exist in the gaps.The integrity of energetic materials has been improved.Thermal analysis shows that the addition of P(VDF-HFP)greatly changes the thermal reaction processes,and the exothermic peaks appear early,but the utilization of fuel and oxidizer is not efficient from the XRD results.Furthermore,the appropriate addition of P(VDF-HFP)can directly reduce the ignition energy threshold and increase the combustion time,which is necessary for the potential ignition charge application.The possible reasons for above phenomena are discussed and analyzed.This research provides a reference for improvement of thermitebased ignition charge formulation.

自发性脱位于玻璃体腔的人工晶状体囊袋复合体经巩膜固定的疗效观察

目的:探讨自发性脱位于玻璃体腔的人工晶状体囊袋复合体经巩膜缝合固定的手术效果。方法:回顾性病例对照研究。2017-04/2019-06对自发性脱位进入玻璃体腔内的人工晶状体囊袋复合体8例8眼(研究组)采取23G玻璃体切割术联合人工晶状体囊袋复合体巩膜缝合固定治疗。选取同期玻璃体晶状体切除术后行折叠人工晶状体悬吊手术10例10眼为对照组。术后7、30、60d随访两组裸眼视力、最佳矫正视力、眼压、角膜散光、IOL的偏心值与倾斜度和手术并发症。结果:研究组8眼人工晶状体囊袋复合体顺利经巩膜缝合固定,对照组10眼成功植入并缝合固定人工晶状体。视力:两组内术后7、30、60d裸眼视力和术前比较,均提高(P<0.05);两组术后7、30、60d矫正视力较术前无差异(P>0.05)。术后两组裸眼视力无差异(P>0.05),术后7d与术后30、60d裸眼视力有差异(P<0.001);术后7、30、60d两组矫正视力无差异(P>0.05)。术后7、30、60d两组患者眼压均正常(10~21mmHg),组内及组间对比均无统计学意义(P>0.05)。角膜散光:组内比较:对照组术前与术后30、60d比较,研究组术前与术后30d比较,均有差异(P<0.05),散光值较术前增大;术后30、60d,对照组术后散光度均大于研究组(P<0.05)。IOL的偏心值与倾斜度:术后30、60d研究组均低于对照组(P<0.05)。结论:对脱位于玻璃体腔内的人工晶状体囊袋复合体采取23G玻璃体切割术联合经巩膜缝合固定手术可以减少手术步骤,降低手术性创伤,较好恢复人工晶状体的位置和改善视觉质量。

Controlled synthesis of monodispersed spherical ruthenium powders

Monodispersed spherical Ru powders are essential for fabricating high-performance Ru sputtering targets,which have applications in very-large-scale integration circuits and magnetic recording devices.However,the synthesis of such powders remains a major challenge.Here,we reported the synthesis of monodispersed spherical Ru powders through controlling the molar ratio of SO_(4)^(2-)to Ru^(3+)in urea homogeneous precipitation solution and the annealing conditions.Without the addition of(NH4)2SO_(4)into the reaction solution,only gel-like precipitation particles were obtained.Once introducing(NH_(4))_(2)SO_(4) into the reaction solution and controlling the molar ratio of SO_(4)^(2-)to Ru3+between 0.50 and 1.00,monodispersed spherical precursor powders were obtained.The nucleation and growth of monodispersed spherical precursor particles in solution were found to conform to LaMer's model.Through controlled annealing at 450℃in a hydrogen atmosphere,the obtained metallic Ru powder with an average particle size of 135 nm inherited the spherical morphology and excellent dispersity from the monodispersed spherical precursor powders.These results and findings would deepen the understanding of the preparation of monodispersed Ru and Ru-like powders.

A Novel laser scanning method for metallization of alumina substrate by copper

A laser scanning method was developed to metalize the surface of alumina substrates with copper.The modeling of the heating and cooling rates of the samples during the laser scanning process indicates that the metallization process involves the rapid melting and solidification of Al_(2)O_(3) and Cu and the evaporation and deposition of part of the Cu.The surface of the metalized alumina substrate was composed of copper spheres(~60μm in diameter)embedded into the alumina substrate and a thin layer of CuAlO_(2).

Differentially methylated genomic fragments related with sexual dimorphism of rice pests, Sogatella furcifera

Sogatella furcifera （Hovarth） is a major rice pest with sexual dimorphism. The objective of the current research was to monitor differentially cytosine methylation at CCGG sequences in male and female adults of S. furcifera to determine the association between gene methylation and sexual phenotypes using methylation-sensitive representa- tional difference analysis. After the second subtractive hybridization, four differentially methylated DNA bands were obtained and sequenced. Ten different fragments were found. One fragment from the positive hybridization was 120 bp, and highly similar to the tram- track genes from Nasonia vitripennis. Another fragment from the reverse hybridization was 414 bp, and homologous to the 28S rRNA gene of S. furcifera with a similarity rate as high as 99%. We also discussed how DNA methylation of tramtrack and 28S rRNA genes produced effects on sexual differentiation and development. These results provide potential evidence that DNA methylation of some genes may be related to sexual phenotype variations in S.furcifera and will facilitate future studies on the epigenetic mechanisms of insect sexual dimorphism.