Micro defects formation and dynamic response analysis of steel plate of quasi-cracking area subjected to explosive load

As the protective component,steel plate had attracted extensive attention because of frequently threats of explosive loads.In this paper,the evolution of microstructure and the mechanism of damage in the quasi-cracking area of steel plate subjected to explosive load were discussed and the relationships between micro defects and dynamic mechanical response were revealed.After the explosion experiment,five observation points were selected equidistant from the quasi-cracking area of the section of the steel plate along the thickness direction,and the characteristics of micro defects at the observation points were analyzed by optical microscope(OM),scanning electron microscope(SEM) and electron backscattered diffraction(EBSD).The observation result shows that many slip bands(SBs) appeared,and the grain orientation changed obviously in the steel plate,the two were the main damage types of micro defects.In addition,cracks,peeling pits,grooves and other lager micro defects were appeared in the lower area of the plate.The stress parameters of the observation points were obtained through an effective numerical model.The mechanism of damage generation and crack propagation in the quasicracking area were clarified by comparing the specific impulse of each observation point with the corresponding micro defects.The result shows that the generation and expansion of micro defects are related to the stress area(i.e.the upper compression area,the neutral plane area,and the lower tension area).The micro defects gather and expand at the grain boundary,and will become macroscopic damage under the continuous action of tensile stress.Besides,the micro defects at the midpoint of the section of the steel plate in the direction away from the explosion center(i.e.the horizontal direction) were also studied.It was found that the specific impulse at these positions were much smaller than that in the thickness direction,the micro defects were only SBs and a few micro cracks,and the those decreased with the increase of the distance from the explosion center.

Effect of GP73 silencing on proliferation and apoptosis in hepatocellular cancer

AIM: To investigate the roles of Golgi protein(GP) 73 in the regulation of cell proliferation and apoptosis. METHODS: Stealth RNAi targeting GP73 gene sequence was used to silence its expression in Hep G2 cells and Bel7402 cells. Stealth RNAi effects were assessed by reverse transcriptase polymerase chain reaction and ELISA. Cell proliferation assay and cell cycle analysis were assessed by MTT assay and flow cytometry. Apoptosis was assessed by flow cytometry andtransmission electron microscopy. Apoptosis-related proteins were assessed by western immunoblot analysis.RESULTS: Stealth RNAi targeting GP73 gene sequence markedly reduced the expression of GP73 gene. The reduction of GP73 in Hep G2 cells and Bel7402 cells inhibited cell proliferation and induced apoptosis, however, terminal apoptosis occurred in Hep G2 cells, but early apoptosis occurred in Bel7402 cells. Reduced expression of GP73 gene might lead to a reduction in Bcl-2/Bax ratio, an increase in cytochrome c, but a reduction in capase-3.CONCLUSION: GP73 might play an important role in proliferation and apoptosis in hepatocellular carcinoma cells.

In situ observations of austenite grain growth in Fe-C-Mn-Si super bainitic steel

In situ observations of austenite grain growth in Fe-C-Mn-Si super bainitic steel were conducted on a high-temperature laser scanning confocal microscope during continuous heating and subsequent isothermal holding at 850, 1000, and 1100℃ for 30 min. A grain growth model was proposed based on experimental results. It is indicated that the austenite grain size increases with austenitizing temperature and holding time. When the austenitizing temperature is above 1100℃, the austenite grains grow rapidly, and abnormal austenite grains occur. In addition, the effect of heating rate on austenite grain growth was investigated, and the relation between austenite grains and bainite morphology after bainitic transformations was also discussed.

Chemotherapy for patients with gastric cancer after complete resection: A network meta-analysis

AIM:To conduct a network meta-analysis to evaluate the effectiveness of different chemotherapy regimens for patients with gastric cancer.METHODS:PubMed(1966-2011.12),the Cochrane Library(2011 Issue 2)and EMBASE(1974-2011.12)were searched with the terms"gastric cancer"and"chemotherapy",as well as the medical subject headings.References from relevant articles and conferences were also included.Patients who had previous gastric surgery,radiation before or after surgery or chemotherapy before surgery were excluded.In this study,only randomized controlled trials(RCTs)were considered,and the end-point was the overall mortality.Direct comparisons were performed using traditional meta-analysis whereas indirect comparisons were performed using network meta-analysis.RESULTS:In total,31 RCTs with 7120 patients were included.Five chemotherapy regimens,fluorouracil(FU)+BCNU,FU+methyl-CCNU(mCCNU),FU+cisplatin,FU+anthracyclines and FU+mitomycin c(MMC)+cytarabine(Ara-c),were found to be less beneficial in terms of overall mortality.In contrast,four chemotherapy regimens were effective for the patients after surgery,including FU+MMC+adriamycin(FMA),FU+MMC(FM),Tegafur and MMC,There was no significant difference in terms of overall mortality among these regimens.The evidence for the FM regimen and MMC regimen was poor.Additionally,the FMA regimen,which includes a variety of chemotherapy drugs and causes many side effects,was not better than the Tegafur regimen.CONCLUSION:Although the four chemotherapy regimens were effective in patients with gastric cancer after surgery and the overall mortality revealed no significant difference among them in the network metaanalysis,thorough analysis of the results recommends Tegafur as the first-line adjuvant chemotherapy regimen for patients after complete resection.

Manual reduction with traditional small splints for distal radius fracture in older patients

Objective:To investigate the effect of manual reduction with traditional small splints fixation for distal radius fractures in older patients in the emergency department.Methods:Older patients(aged at least 60 years)with distal radius fractures were enrolled in this study.The patients were randomly divided into the treatment group and the control group.The treatment group was treated with manual reduction and small splints fixation.The control group was treated with manual reduction and resin plaster fixation.Before treatment,after reduction,and 3 months after treatment,the palmar tilt angle,ulnar deviation angle,and radial length were recorded.Before treatment and 3 months after treatment,the Cooney wrist joint scores were recorded.The time of fracture healing and related adverse events during the treatment were recorded.Results:Before treatment and after reduction,there were no statistically significant differences between the two groups in palmar tilt angle,ulnar deviation angle,or radial length(P>0.05).Three months after treatment,the palmar tilt angle,ulnar deviation angle,and radial length of the treatment group were better than those of the control group(P<0.05).The Cooney wrist scores of the treatment group was significantly higher than that of the control group three months after the treatment(P<0.05).The time of fracture healing of the treatment group was shorter than that of the control group,but the difference was no statistically significant(P>0.05).Conclusions:Compared with resin plaster fixation,traditional small splints fixation for distal radius fractures in older patients have the advantages of less loss of fracture reduction and faster functional recovery.Besides,the method is simple and low cost thus,it needs to be promoted.

Concept of hydrophobic Li^(+)-solvated structure for high performances lithium metal batteries

The large-scale application of lithium metal batteries remains a challenge due to the hydrolysis of LiPF_(6),which can induce capacity fade and series of safety issues.Prof.Ma and his co-workers have designed a hydrophobic Li^(+)-solvated structure to obtain high performances lithium metal batteries.The specific functional groups of theadditive,hexafluoroisopropyl acrylate.

Effect of annealing time and phosphorus addition on bake hardening behavior of ultra-low carbon bake hardening steel

The relationship of the P and C grain boundary segregation and its effect on bake hardening behavior were investigated in ultra-low carbon bake hardening (ULC-BH)steel with and without P addition annealed at 810 ℃ for various time using electron probe micro-analyzer,electroh backscattered diffraction,and three-dimensional atomic probe techniques.Results revealed that P addition and annealing duration considerably affected the bake hardening behavior of experimental steel. The BH value of ULC-BH steel without P addition is lower than that with P addition within a short annealing time,and the difference in the BH value gradually decreases as the annealing duration is prolonged.P segregation is dominant in terms of a high P bulk content in steels with P addition at the expense of C segregation during annealing.By contrast,opposite effects are observed in low carbon bake hardening steel.The high residual solute C content in steel with P addition is due to P segregation at the grain boundary.Site competition is mainly responsible for the lower BH value in ULC-BH steel without P addition than that with P addition.As the annealing time is further extended,C segregation begins at grain boundary despite the delayed P segregation,leading to a gradual decrease in the solute concentration in the matrix of steels with P addition.C and P segregations reach the equilibrium as the annealing time increases to 60 min at 810 ℃ in the two steel samples.Theoretical calculations reveal that the residual solute C concentration in the matrix decreases to zero,and this finding is consistent with the change trend of the bake hardening value.Hence,the C segregation at grain boundary. adversely influences the bake hardening property of ULC-BH steel.

A new subfamily of the grasshopper （Orthoptera： Acridoidea： Gomphoceridae） from the Tibetan Plateau of China

This paper reports a new subfamily, a new genus and a new species, that is, Pacrinae subfam, nov., Pacris gen. nov and Pacris xizangensis sp. nov in Gomphoceridae. The new subfamily is allied to Orinhippinae of Gomphoeeridae and it differs from the latter by wings and tympanum absent. The new genus is similar to Orinhippus Uvarov, 1921 but differs from the latter in： （i） foveolae absent; （ii） tegmina absent; （iii） tympanum absent; （iv） hind margin of pronotum with incised in the middle. Type specimens are deposited in the Museum of Hebei University, Baoding, China.