The copper polymetallic deposits and resource potential in the Tibet Plateau

Many large and super-large copper deposits have been discovered and explored in the Tibet Plateau,which makes it the most important copper resource reserve and development base in China.Based on the work of the research team,the paper summarizes the geological characteristics of the main copper deposits in Tibet and puts forward a further prospecting direction.A series of large accumulated metal deposits or ore districts from subduction of Tethys oceanic crust to India-Asia collisionhave been discovered,such as Duolong Cu(Au)ore district and Jiama copper polymetallic deposit.The ore deposits in the Duolong ore district are located in the lowstand domain,the top of lowstand domain,and the highstand domain of the same magmatic-hydrothermal metallogenic system,and their relative positions are the indicators for related deposits in the Bangong Co-Nujiang metallogenic belt.The polycentric metallogenic model of the Jiama copper polymetallic deposit is an important inspiration for the exploration of the porphyry mineralization related to collision orogeny.Further mineral exploration in the Tibet Plateau should be focused on the continental volcanic rocks related to porphyry-epithermal deposits,orogenic gold deposits,hydrothermal Pb-Zn deposits related to nappe structures,skarn Cu(Au)and polymetallic deposits,and the Miocene W-Sn polymetallic deposits.

Self-healed microcracks in polymer bonded explosives via thermoreversible covalent bond and hydrogen actions

Polymeric materials used for the polymer bonded explosive(PBX)or other energetic composite materials(ECMs)that simultaneously possess excellent mechanical properties and high self-healing ability,convenient healing,and facile fabrication are always a huge challenge.Herein,self-healing linear polyurethane elastomers(PTMEG2000-IPDI-DAPU,denoted as 2I-DAPU)with high healing efficiency and mechanical properties were facilely fabricated by constructing reversible covalent bonds and dynamic hard domains into polymer chains.Furthermore,a TATB-based PBX using as-prepared 2I-DAPU polymer as the binder was constructed,disclosing an excellent self-healing property to heal cracks generated during fabrication,transportation and storage.The damage healing manner of such a PBX sample was investigated by means of prefabricated damage through mechanical load,heal treatment via heating at high temperature,and CT-scanning the inner structure and mechanical property characterization via Brazilian test.The self-healing mechanism of internal damage in PBX was preliminarily explored.We propose that this 2I-DAPU binder with Diels-Alder bonds could generate plentiful active surface groups resulting from damage and drive self-healing at fitting temperature and increase the slightly packed hard phase via incorporating a small amount of hydrogen bonds.This work may offer a novel strategy for improving mechanical property and healing ability in the field of self-healing material which could help expand its applications with enhanced versatility in mechanical-enhanced functional materials.

The effect of wax coating,aluminum and ammonium perchlorate on impact sensitivity of HMX

Interaction of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX)/ammonium perchlorate(AP) and its effect on mechanical sensitivity may result in some restrictions for the application of AP/HMX system in high energetic weapon system. In this work, impact sensitivity test is used to study the effects of wax coating of HMX, AP and aluminum(Al) powder on sensitivity properties of HMX/AP/Al mixtures.Thermogravimetry-differential scanning calorimetry(TG-DSC) analysis has been developed to investigate the mechanism of interaction between HMX and AP during the course of thermal decomposition of HMX/AP/AI mixtures. The results show that severe interaction effect exists between AP and HMX, which causes the impact sensitivity(H_(50)) to become smaller. The impact energy(E_(50)) of mixture can be improved under the circumstances of effective separating HMX from AP by surface coating with Wax. AP may firstly engender low-temperature decomposition under the circumstance of external heat or mechanical impact, which causes the exothermic peak of HMX forward shift about 28 C. The gaseous product releasing from thermal decomposition of HMX accelerates further decomposition of AP. For HMX/AP composite system, the interactive catalysis effect between AP and HMX can be eliminated mostly by adding a great deal of Al powder(i.e. above 30%).

无能隙量子自旋液体和正方晶格自旋1/2阻挫反铁磁模型的相图

自高温超导发现以来,正方晶格上由自旋为1/2构成的包括近邻和次近邻海森堡相互作用的阻挫反铁磁模型,即J1±J2模型,因其基态被认为可以作为铜基超导的母态,在过去30多年中得到了广泛关注和深入研究.该模型包含的相互作用形式简单,如今也成为用来研究正方晶格上阻挫磁性的基本理论模型.但其基态性质仍然是一个悬而未决的问题.本文作者利用最近发展的二维张量网络态算法,对该模型进行了迄今为止精度最高的计算.详细的数值结果表明这个体系的基态包含了一个无能隙的量子自旋液体和价键固体态.他们进一步计算了相变的临界指数,提出了一个低能有效理论来描述这个量子自旋液体,并探讨了这个量子自旋液体与解禁闭量子临界性的关系.该工作通过仔细比较二维张量网络态和人们常用的密度矩阵重整化群两种算法的结果,提供了在正方晶格阻挫磁性体系的研究上第一个超越密度矩阵重整化方法的例子.他们也解释了以前研究结果矛盾之处的来源,为用二维张量网络态解决量子多体问题提供了一个范本.