Nacre-inspired interface structure design of polymer bonded explosives toward significantly enhanced mechanical performance

Realizing effective enhancement to the structure of interface region between explosive crystals and polymer binder plays a key role in improving the mechanical properties of the current polymer bonded explosives(PBXs).Herein,inspired by the structure of natural nacre which possesses outstanding mechanical performance,a kind of nacre-like structural layer is constructed in the interface region of PBXs composites,making use of two-dimensional graphene sheets and one-dimensional bio-macromolecules of cellulose as inorganic and organic building blocks,respectively.Our results reveal that the constructed nacre-like structural layer can effectively improve the interfacial strength and then endow the PBXs composites with significantly enhanced mechanical properties involving of creep resistance,Brazilian strength and fracture toughness,demonstrating the obvious advantage of such bioinspired interface structure design strategy.In addition,the thermal conduction performance of PBXs composites also exhibits noticeable enhancement due to the remarkable phonon transport capability endowed by the asdesigned nacre-like structural layer.We believe this work provides a novel design route to conquer the issue of weak interfacial strength in PBXs composites and greatly increase the comprehensive properties for better meeting the higher requirements proposed to the explosive part of weapon equipment in new era.

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%).

A BRCA1 Splice Site Variant Responsible for Familial Ovarian Cancer in a Han-Chinese Family

Objective Ovarian cancer(OC)is one of the most common and most lethal gynecological malignancies.OC has an age-dependent incidence and occurs more commonly in females older than 50 years old.Most OC patients are diagnosed at an advanced stage and have a poor prognosis.Germline mutations in the BRCA1 DNA repair associated gene(BRCA1)and the BRCA2 DNA repair associated gene(BRCA2)account for 20%–25%of epithelial ovarian cancer(EOC).BRCA1 germline mutations are more common in Chinese EOC patients.Methods This study reported a three-generation Han-Chinese family containing four EOC patients and a rectal adenocarcinoma patient.Whole-exome sequencing was performed on two EOC patients and an unaffected individual.Variant validation was also performed in all available members by Sanger sequencing.Results A heterozygous splice site variant,c.4358-2A>G in the BRCA1 gene,was identified.Bioinformatic analysis showed that the variant may change the splicing machinery.Conclusion The BRCA1 splice site variant,c.4358-2A>G was identified as the likely genetic cause for EOC,and may also be associated with the increased risk of rectal adenocarcinoma in the family.The findings were beneficial for genetic counseling,helpful for cancer prevention in other family members,and may facilitate therapy decision-making in the future to reduce cancer lethality.

Level of proinsulin in association with cardiovascular risk factors and sleep snoring

AIM: To explore the relationship between the level of proinsulin with cardiovascular risk factors and sleep snoring.METHODS: Based on the random stratified sampling principle, 1 193 Chinese residents in Pizhou City, Jiangsu Province (530 males and 663 females, aged 35-59 years with an average age of 46.69 years) were recruited. Their sleep snoring habits were investigated. Biotin-avidin based double mAbs ELISA was used to detect specific insulin and proinsulin, and a risk factor score was established to evaluate the individuals according to the number of their risk factors.RESULTS: The results of Spearman correlation analysis and covariate ANOVA analysis after age and sex were controlled, indicated that not only the level of proinsulin (r = 0.156, P = 0.000, F= 5.980 P = 0.000), but also cardiovascular risk factors score (r = 0.194, P = 0.000,F= 11.135, P = 0.000) significantly associated with the frequency of sleep snoring, and the significant relationship between true insulin and frequency of sleep snoring was only shown in the covariate ANOVA analysis (F = 2.868,P = 0.022). The result of multivariate stepwise logistic regression after age, sex, body mass index, waist circumference and true insulin were controlled showed that proinsulin (division by interval of quartile) was an independent risk factor for sleep snoring (OR = 1.220,95%CI: 1.085-1.373, P = 0.001).CONCLUSION: The interaction of cardiovascular risk factors clustering, high proinsulin level and sleep breathing disorder may be a syndrome, which has not been recognized in human beings so far.

A correlation between acute kidney injury and myonecrosis after scheduled percutaneous coronary intervention

Slight elevations in cardiac troponin I and T are frequently observed after percutaneous coronary intervention (PCI). Contrast-induced acute kidney injury (CI-AKI) is a complex syndrome induced by exposure to intravascular contrast media (CM). Currently, the relationships between the CM, pre-existing kidney insufficiency, CI-AKI, and myonecrosis after elective PCI are unclear. To investigate the relationship between CI-AKI and post-procedural myonecrosis (PMN) after PCI, we analyzed 327 non-ST-segment elevation acute coronary syndrome subjects undertaking elective PCI. The levels of cardiac troponins (cTns), cTnI and cTnT, at baseline and on at least one occasion 18-24 h after PCI were measured. We also recorded serum levels of creatinine (SCr) and the urine albumin:creatinine ratio (ACR) before coronary angiography, and 24-48 h and 48-72 h after contrast administration. A post-procedure increase in cTns was detected in 16.21% (53/327) of subjects with cTns levels >99th to 5×99th percentile upper reference limit (URL). Twenty-seven patients (8.26%) developed CI-AKI. CI-AKI occurred more often in subjects with PMN than in those without PMN (20.8% versus 5.8%, respectively, P=0.001). Multiple logistic regression analysis revealed that pre-existing microalbuminuria (MA) was an important independent predictor of PMN (OR:3.31; 95% CI:1.26-8.65, P=0.01). However, there was no correlation between the incidence of CI-AKI and PMN (OR:2.38; 95% CI:0.88-6.46, P=0.09). We conclude that pre-existing MA was not only an important independent predictor of CI-AKI but also of PMN.