Thermal decomposition and kinetics of plastic bonded explosives based on mixture of HMX and TATB with polymer matrices

This work describes thermal decomposition behaviour of plastic bonded explosives(PBXs) based on mixture of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX) and 2,4,6-triamino-1,3,5-trinitrobenzene(TATB)with Viton A as polymer binder. Thermal decomposition of PBXs was undertaken by applying simultaneous thermal analysis(STA) and differential scanning calorimetry(DSC) to investigate influence of the HMX amount on thermal behavior and its kinetics. Thermogravimetric analysis(TGA) indicated that the thermal decomposition of PBXs based on mixture of HMX and TATB was occurred in a three-steps. The first step was mainly due to decomposition of HMX. The second step was ascribed due to decomposition of TATB, while the third step was occurred due to decomposition of the polymer matrices. The thermal decomposition % was increased with increasing HMX amount. The kinetics related to thermal decomposition were investigated under non-isothermal for a single heating rate measurement. The variation in the activation energy of PBXs based on mixture of HMX and TATB was observed with varying the HMX amount. The kinetics from the results of TGA data at various heating rates under non-isothermal conditions were also calculated by Flynn—Wall—Ozawa(FWO) and Kissinger-Akahira-Sunose(KAS)methods. The activation energies calculated by employing FWO method were very close to those obtained by KAS method. The mean activation energy calculated by FWO and KAS methods was also a good agreement with the activation energy obtained from single heating rate measurement in the first step decomposition.

Production and characterisation of new bioresorbable radiopaque Mg–Zn–Y alloy to improve X-ray visibility of polymeric scaffolds

For the medical diagnosis,radiopaque materials(RM)made from high specific gravity elements like Pt,Au,Ta,Iodine,Bromine are either attached or blended or coated on an implant to makes it detectable under X-ray/Fluoroscopy/CT-Scan.RM facilitate the surgeon in an operation theatre to position an implant during the surgery.Mainly,RM are non-degradable,thus in case of biodegradable implants,it may detach from the body and accumulate in vital organ cause serious health issue.Therefore,a new bioresorbable radiopaque material(BRM)was produced by alloying the high specific gravity elements Zn(35%w/w)and Y(4%w/w)with Mg metal.In this alloy,three main phases were identified,alpha Mg,Mg_(7)Zn_(3)and icosahedral quasicrystalline I-phase Mg3Zn6Y,which reinforce the Mg matrix.Hereafter,BRM was powdered to a size of less than 25 microns and blended in different ratios with bioresorbable poly-L-lactic acid(PLLA)for fabricating PLLA/BRM bio-composite.BRM microparticles were uniformly distributed and interfacial bonded with the matrix.The X-ray was passed through bio-composite to captureμCT radiograph for evaluating linear attenuation co-efficient(μ)and optical density(OD).Thermal analysis reveals that BRM particles act as a nucleating site and enhance the crystallinity of the polymeric chain.During the In Vitro accelerated degradation study,the alkaline nature of BRM neutralise the acidity of PLLA and balance the pH of the body fluid to reduce the inflammatory reactions,but this compromises the stability of the polymer as it increases the decomposition rate.

各种煤的热力学第二定律分析

0 前言不可回收的能源耗尽及其高成本迫使工程师们再考虑如何合理有效地利用能源这一问题。通常的第一定律分析,尽管必要,但不能给出能源系统各组成的极限和潜力的完整结构。因此,这可能会导致不恰当的设备设计及匹配。第二定律分析可决定希望能源装置或工艺所作的最大功,例如由于电能几乎可完全转化成机械功,因此它的质量比热能高。能源装置和工艺的第二定律分析不是新兴的,可追溯到上一世纪。但是,直到最近。

Enhanced osseointegration of drug eluting nanotubular dental implants: An in vitro and in vivo study

Faster and predictable osseointegration is crucial for the success of dental implants, especially in patients with compromised local or systemic conditions. Despite various surface modifications on the commercially available Titanium (Ti) dental implants, the bioactivity of Ti is still low. Thus, to achieve both biological and therapeutic activity on titanium surfaces, surface modification techniques such as titanium nanotubes have been studied as nanotube surfaces can hold therapeutic drugs and molecules. The main aim of the present research work is to study the early osseointegration around the novel Simvastatin drug eluting nanotubular dental implant. In the present research, the titanium nanotubes were fabricated on the screw-shaped dental implant surface and the Simvastatin drug was loaded into the nanotubes using the ultrasonication dip method. In vitro and In vivo studies were carried out on the modified dental implants. In vitro cell culture study reported enhanced osteogenic activity on the drug-loaded nanotube surface implants. The in vivo animal studies were evaluated by micro-CT, histopathology, and reverse torque removal analysis methods. The test results showed faster osseointegration with the strong interface on the Simvastatin drug-loaded implant surface at 4 weeks of healing as compared to the control implants.

Feasibility of one-shot dilation access in the pediatric age group

Objective To compare sequential fascial dilation(SFD)versus one-shot dilation(OSD)in the pediatric patients undergoing percutaneous nephrolithotomy.Methods The present study is an observational study.The study subjects were divided into two groups.In group 1,renal dilation was done using the SFD and in group 2,renal dilation was done using the OSD.The amount of time exposed to radiation during access to pelvicalyceal system was estimated.Complications,stone free rates,ancillary procedures for residual stones and hospital stay were compared.Modified Clavien-Dindo classification was used for grading the complications.Results Radiation exposure and operative time were less in OSD group(95%confidence interval(CI)3.068 to 14.072,and 2.565 to 12.435,p<0.005).The mean drop of hematocrit was statistically less significant in OSD group(p=0.032).In both groups,complications,stone free rate and hospital stay were statistically insignificant.Conclusions OSD is feasible in the children with reduced radiation exposure and shorter operative time.The outcome was similar to SFD.