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Iacono, Diego, Erin K. Murphy, Cheryl D. Stimpson, Fabio Leonessa e Daniel P. Perl. "Double Blast Wave Primary Effect on Synaptic, Glymphatic, Myelin, Neuronal and Neurovascular Markers". Brain Sciences 13, n. 2 (8 febbraio 2023): 286. http://dx.doi.org/10.3390/brainsci13020286.
Testo completoAbstract (sommario):
Explosive blasts are associated with neurological consequences as a result of blast waves impact on the brain. Yet, the neuropathologic and molecular consequences due to blast waves vs. blunt-TBI are not fully understood. An explosive-driven blast-generating system was used to reproduce blast wave exposure and examine pathological and molecular changes generated by primary wave effects of blast exposure. We assessed if pre- and post-synaptic (synaptophysin, PSD-95, spinophilin, GAP-43), neuronal (NF-L), glymphatic (LYVE1, podoplanin), myelin (MBP), neurovascular (AQP4, S100β, PDGF) and genomic (DNA polymerase-β, RNA polymerase II) markers could be altered across different brain regions of double blast vs. sham animals. Twelve male rats exposed to two consecutive blasts were compared to 12 control/sham rats. Western blot, ELISA, and immunofluorescence analyses were performed across the frontal cortex, hippocampus, cerebellum, and brainstem. The results showed altered levels of AQP4, S100β, DNA-polymerase-β, PDGF, synaptophysin and PSD-95 in double blast vs. sham animals in most of the examined regions. These data indicate that blast-generated changes are preferentially associated with neurovascular, glymphatic, and DNA repair markers, especially in the brainstem. Moreover, these changes were not accompanied by behavioral changes and corroborate the hypothesis for which an asymptomatic altered status is caused by repeated blast exposures.
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Hu, Zhijian, Jian Q. Fang e Lizhi Z. Sun. "Blast effect zones and damage mechanisms of concrete bridges under above-deck car-bomb attacks". International Journal of Damage Mechanics 27, n. 8 (10 maggio 2017): 1156–72. http://dx.doi.org/10.1177/1056789517708827.
Testo completoAbstract (sommario):
Above-deck car-bomb attacks cause significant effects on engineering structures from those of explosive blasts in the free air. In this paper, a post-disaster investigation for an existing bridge under above-deck car-bomb blast loading is presented. The crack distribution and damage deformation of the blast loaded girders are systematically investigated, and the blast effect zone is proposed to describe the blast loading distributions on girders and to characterize the girder structural behavior. The girder failure is dominated by one of the three typical damage mechanisms: shear, flexural-shear, and flexural, depending on the blast effect zone where the girder is located. The study also indicates that the isolation effect of the vehicle can significantly affect the blast loading distribution on structures, even though the isolation effect is localized in a region with a small standoff distance. It is gradually attenuated by the increase of the standoff distance. Numerical analysis is conducted to verify the findings by simulating the truck isolation effect with a steel plate.
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Fields, David M., Nils Olav Handegard, John Dalen, Christiane Eichner, Ketil Malde, Ørjan Karlsen, Anne Berit Skiftesvik, Caroline M. F. Durif e Howard I. Browman. "Airgun blasts used in marine seismic surveys have limited effects on mortality, and no sublethal effects on behaviour or gene expression, in the copepod Calanus finmarchicus". ICES Journal of Marine Science 76, n. 7 (7 agosto 2019): 2033–44. http://dx.doi.org/10.1093/icesjms/fsz126.
Testo completoAbstract (sommario):
Abstract Seismic surveys use airguns that emit low frequency high magnitude sound to detect subsea resources and to map seabed geology. The effect of seismic blasts on Calanus spp., a key food source for commercially important fish, was assessed in field experiments. Immediate mortality of copepods was significantly different from controls at distances of 5 m or less from the airguns. Mortality 1 week after the airgun blast was significantly higher—by 9% relative to controls—in the copepods placed 10 m from the airgun blast but was not significantly different from the controls at a distance of 20 m from the airgun blast. The increase in mortality—relative to controls—did not exceed 30% at any distance from the airgun blast. Only two genes changed in response to the airgun blast; however, their function is unknown. There were no sublethal effects of the seismic blasts on the escape performance or the sensory threshold needed to initiate an escape response at any of the distances from the airgun blast that were tested. Results from these experiments suggest that seismic blasts have limited effects on the mortality or escape response of Calanus sp. within 10 m of the blast and no measurable impact at greater distances.
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Tsao, Jack W., Lauren A. Stentz, Minoo Rouhanian, Robin S. Howard, Briana N. Perry, F. Jay Haran, Paul F. Pasquina et al. "Effect of concussion and blast exposure on symptoms after military deployment". Neurology 89, n. 19 (13 ottobre 2017): 2010–16. http://dx.doi.org/10.1212/wnl.0000000000004616.
Testo completoAbstract (sommario):
Objective:To examine whether blast exposure alone and blast-associated concussion result in similar neurologic and mental health symptoms.Methods:A 14-item questionnaire was administered to male US Marines on their return from deployment in Iraq and/or Afghanistan.Results:A total of 2,612 Marines (median age 22 years) completed the survey. Of those, 2,320 (88.9%) reported exposure to ≥1 blast during their current and/or prior deployments. In addition, 1,022 (39.1%) reported ≥1 concussion during the current deployment, and 731 (28.0%) had experienced at least 1 prior lifetime concussion. Marines were more likely to have sustained a concussion during the current deployment if they had a history of 1 (odds ratio [OR] 1.5, 95% confidence interval [CI] 1.2–2.0) or ≥1 (OR 2.3, 95% CI 1.7–3.0) prior concussion. The most common symptoms were trouble sleeping (38.4%), irritability (37.9%), tinnitus (33.8%), and headaches (33.3%). Compared to those experiencing blast exposure without injury, Marines either experiencing a concussion during the current deployment or being moved or injured by a blast had an increased risk of postinjury symptoms.Conclusions:There appears to be a continuum of increasing total symptoms from no exposure to blast exposure plus both current deployment concussion and past concussion. Concussion had a greater influence than blast exposure alone on the presence of postdeployment symptoms. A high blast injury score can be used to triage those exposed to explosive blasts for evaluation.
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Sainoki, Atsushi, e Hani S. Mitri. "Numerical simulation of rock mass vibrations induced by nearby production blast". Canadian Geotechnical Journal 51, n. 11 (novembre 2014): 1253–62. http://dx.doi.org/10.1139/cgj-2013-0480.
Testo completoAbstract (sommario):
It is of importance to understand the effect of production blasts on the surrounding rock formations in underground mines. This study presents a numerical procedure to simulate stress waves resulting from nearby production blasts. First, the damping coefficient and peak borehole pressure are calibrated using a dynamic numerical model of a single blast hole. The resulting time-varying particle velocities in the surrounding rock mass at the specified points are calculated. These are then used as input parameters in a three-dimensional mine-wide model, considering a positional relationship between the blast hole and the specified points on the wall rock. The mine-wide model encompasses a fault running parallel to a steeply dipping, tabular ore deposit. Dynamic analysis simulating the effect of production blasts is conducted after the extraction of mining blocks with static analysis. In this study, variations of stresses along the fault due to blast-induced stress waves are examined. Results demonstrate that the developed methodology can reasonably simulate stress changes induced by stress waves on the fault. The methodology considers blast sequences and time-varying blast loads that vary according to the positional relationship between the blast holes and the specified points on the wall rock.
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Tan, X. Gary, e Peter Matic. "Simulation of Cumulative Exposure Statistics for Blast Pressure Transmission Into the Brain". Military Medicine 185, Supplement_1 (gennaio 2020): 214–26. http://dx.doi.org/10.1093/milmed/usz308.
Testo completoAbstract (sommario):
Abstract Introduction This study develops and demonstrates an analysis approach to understand the statistics of cumulative pressure exposure of the brain to repetitive blasts events. Materials and Methods A finite element model of blast loading on the head was used for brain model biomechanical responses. The cumulative pressure exposure fraction (CPEF), ranging from 0.0 to 1.0, was used to characterize the extent and repetition of high pressures. Monte Carlo simulations were performed to generate repetitive blast cumulative exposures. Results The blast orientation effect is as influential as the blast overpressure magnitudes. A 75° (from the side) blast orientation can produce CPEF values exceeding traumatic brain injury pressure thresholds >0.95 while, for the same blast overpressure, a 0° (front) blast orientation results in a CPEF <0.25. Monte Carlo results for different sequences reflecting notional operational and training environments show that both mean values and standard deviations of CPEF reach the statistically equilibrium state at a finite value of n exposures for each sequence. Conclusions Statistical convergence of the brain pressure response metrics versus number of blasts for different exposures characterizes the transitions from “low” to “high” number of blasts and quantitatively highlights the differences between operational and training exposures.
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Akashi, K., M. Harada, T. Shibuya, T. Eto, Y. Takamatsu, T. Teshima e Y. Niho. "Effects of interleukin-4 and interleukin-6 on the proliferation of CD34+ and CD34- blasts from acute myelogenous leukemia". Blood 78, n. 1 (1 luglio 1991): 197–204. http://dx.doi.org/10.1182/blood.v78.1.197.197.
Testo completoAbstract (sommario):
Abstract We studied the effects of interleukin-4 (IL-4) and IL-6 on the growth of leukemic blasts from 40 patients with acute myelogenous leukemia (AML). Patients were selected on the basis of negativity for a series of B-cell antigens including CD10 and CD19. Twenty-one cases were CD34- positive (CD34+) (greater than 15% of blasts) and the remaining 19 were CD34-negative (CD34-) (less than 3% of blasts). IL-4 alone (100 U/ml) could stimulate either DNA synthesis (with greater than 2.0 stimulation index) or leukemic blast colony formation in 24 of 40 AML patients. In the presence of other growth factors, IL-4 showed divergent effects on IL-3-, granulocyte-macrophage colony-stimulating factor-, granulocyte colony-stimulating factor-, or erythropoietin-dependent colony formation. These effects of IL-4 were observed in both CD34+ and CD34- AML cases. IL-6 (100 U/mL) alone could not stimulate DNA synthesis and blast colony formation except for one CD34+ case. On the other hand, IL- 6 showed synergistic effects on IL-3- and IL-4-dependent blast colony formation in 10 of 12 and 7 of 9 CD34+ AML cases, respectively. Among CD34- AML cases, such synergism was seen only in 1 of 12 cases for IL-3- dependent colony formation and in 3 of 7 cases for IL-4-dependent colony formation. The divergent effect of IL-4 and the synergistic effect of IL-6 were also observed in purified CD34+ leukemic blast populations, indicating that these phenomena are not mediated by accessory cells. The present study suggests that IL-4, alone or in combination with other growth factors, has divergent effects on the growth of AML progenitors irrespective of the CD34 expression, and that IL-6 acts synergistically with IL-3 or IL-4 on the growth of leukemic progenitors preferentially in CD34+ AML.
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Akashi, K., M. Harada, T. Shibuya, T. Eto, Y. Takamatsu, T. Teshima e Y. Niho. "Effects of interleukin-4 and interleukin-6 on the proliferation of CD34+ and CD34- blasts from acute myelogenous leukemia". Blood 78, n. 1 (1 luglio 1991): 197–204. http://dx.doi.org/10.1182/blood.v78.1.197.bloodjournal781197.
Testo completoAbstract (sommario):
We studied the effects of interleukin-4 (IL-4) and IL-6 on the growth of leukemic blasts from 40 patients with acute myelogenous leukemia (AML). Patients were selected on the basis of negativity for a series of B-cell antigens including CD10 and CD19. Twenty-one cases were CD34- positive (CD34+) (greater than 15% of blasts) and the remaining 19 were CD34-negative (CD34-) (less than 3% of blasts). IL-4 alone (100 U/ml) could stimulate either DNA synthesis (with greater than 2.0 stimulation index) or leukemic blast colony formation in 24 of 40 AML patients. In the presence of other growth factors, IL-4 showed divergent effects on IL-3-, granulocyte-macrophage colony-stimulating factor-, granulocyte colony-stimulating factor-, or erythropoietin-dependent colony formation. These effects of IL-4 were observed in both CD34+ and CD34- AML cases. IL-6 (100 U/mL) alone could not stimulate DNA synthesis and blast colony formation except for one CD34+ case. On the other hand, IL- 6 showed synergistic effects on IL-3- and IL-4-dependent blast colony formation in 10 of 12 and 7 of 9 CD34+ AML cases, respectively. Among CD34- AML cases, such synergism was seen only in 1 of 12 cases for IL-3- dependent colony formation and in 3 of 7 cases for IL-4-dependent colony formation. The divergent effect of IL-4 and the synergistic effect of IL-6 were also observed in purified CD34+ leukemic blast populations, indicating that these phenomena are not mediated by accessory cells. The present study suggests that IL-4, alone or in combination with other growth factors, has divergent effects on the growth of AML progenitors irrespective of the CD34 expression, and that IL-6 acts synergistically with IL-3 or IL-4 on the growth of leukemic progenitors preferentially in CD34+ AML.
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Kim, Jung H., James A. Goodrich, Robert Situ, Amedeo Rapuano, Hoby Hetherington, Fu Du, Steve Parks et al. "Periventricular White Matter Alterations From Explosive Blast in a Large Animal Model: Mild Traumatic Brain Injury or “Subconcussive” Injury?" Journal of Neuropathology & Experimental Neurology 79, n. 6 (7 aprile 2020): 605–17. http://dx.doi.org/10.1093/jnen/nlaa026.
Testo completoAbstract (sommario):
Abstract The neuropathology of mild traumatic brain injury in humans resulting from exposure to explosive blast is poorly understood as this condition is rarely fatal. A large animal model may better reflect the injury patterns in humans. We investigated the effect of explosive blasts on the constrained head minimizing the effects of whole head motion. Anesthetized Yucatan minipigs, with body and head restrained, were placed in a 3-walled test structure and exposed to 1, 2, or 3 explosive blast shock waves of the same intensity. Axonal injury was studied 3 weeks to 8 months postblast using β-amyloid precursor protein immunohistochemistry. Injury was confined to the periventricular white matter as early as 3–5 weeks after exposure to a single blast. The pattern was also present at 8 months postblast. Animals exposed to 2 and 3 blasts had more axonal injury than those exposed to a single blast. Although such increases in axonal injury may relate to the longer postblast survival time, it may also be due to the increased number of blast exposures. It is possible that the injury observed is due to a condition akin to mild traumatic brain injury or subconcussive injury in humans, and that periventricular injury may have neuropsychiatric implications.
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Kelleher, C., J. Miyauchi, G. Wong, S. Clark, MD Minden e EA McCulloch. "Synergism between recombinant growth factors, GM-CSF and G-CSF, acting on the blast cells of acute myeloblastic leukemia [published erratum appears in Blood 1987 Jul;70(1):339]". Blood 69, n. 5 (1 maggio 1987): 1498–503. http://dx.doi.org/10.1182/blood.v69.5.1498.1498.
Testo completoAbstract (sommario):
Abstract The genes for the hemopoietic growth factors, GM colony-stimulating factor (CSF) and G-CSF have been cloned, and recombinant material is available for both. We tested these recombinant factors for their effects on the blast cells of acute myeloblastic leukemia (AML). Culture methods are available that support both colony formation by AML blasts and the growth of blast stem cells in suspension. Recombinant GM- CSF is active in both culture systems, although to a varying degree. We found that recombinant G-CSF was also effective; however, the two recombinant factors showed striking synergism for the stimulation of blast growth of cells from five of eight AML patients. In these cases, the combination was equivalent to the stimulating activity of supernatants from the continuous cell line 5637. This conditioned medium (HTB9-CM) is considered the standard for blast growth. Blasts from one of the patients grew without added factor. In another instance, recombinant GM-CSF alone was almost as effective as HTB9-CM. In the third case, both recombinant factors were active, but synergism was not observed and their combined effect was not equivalent to that of HTB9-CM. Both GM-CSF and G-CSF were active on normal bone marrow granulopoietic progenitors, but synergism was not observed. We conclude that the marked heterogeneity observed when AML blasts are examined by other criteria is also observed when their response to growth factors is evaluated.
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Kelleher, C., J. Miyauchi, G. Wong, S. Clark, MD Minden e EA McCulloch. "Synergism between recombinant growth factors, GM-CSF and G-CSF, acting on the blast cells of acute myeloblastic leukemia [published erratum appears in Blood 1987 Jul;70(1):339]". Blood 69, n. 5 (1 maggio 1987): 1498–503. http://dx.doi.org/10.1182/blood.v69.5.1498.bloodjournal6951498.
Testo completoAbstract (sommario):
The genes for the hemopoietic growth factors, GM colony-stimulating factor (CSF) and G-CSF have been cloned, and recombinant material is available for both. We tested these recombinant factors for their effects on the blast cells of acute myeloblastic leukemia (AML). Culture methods are available that support both colony formation by AML blasts and the growth of blast stem cells in suspension. Recombinant GM- CSF is active in both culture systems, although to a varying degree. We found that recombinant G-CSF was also effective; however, the two recombinant factors showed striking synergism for the stimulation of blast growth of cells from five of eight AML patients. In these cases, the combination was equivalent to the stimulating activity of supernatants from the continuous cell line 5637. This conditioned medium (HTB9-CM) is considered the standard for blast growth. Blasts from one of the patients grew without added factor. In another instance, recombinant GM-CSF alone was almost as effective as HTB9-CM. In the third case, both recombinant factors were active, but synergism was not observed and their combined effect was not equivalent to that of HTB9-CM. Both GM-CSF and G-CSF were active on normal bone marrow granulopoietic progenitors, but synergism was not observed. We conclude that the marked heterogeneity observed when AML blasts are examined by other criteria is also observed when their response to growth factors is evaluated.
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NAKAMURA, Masakazu, Takashi SUGIYAMA, Takeo UNO e Yukiaki HARA. "Effect of Blast Conditions on the Raceway of the Blast Furnace". Tetsu-to-Hagane 74, n. 8 (1988): 1562–68. http://dx.doi.org/10.2355/tetsutohagane1955.74.8_1562.
Testo completo
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Naeem, Khan, Robert K. Hills, Paul Virgo, Stephen Couzens, Nithiya Clark, Amanda Gilkes, Angela Grech et al. "Significance of Blast CD33 Expression for Effect of Gemtuzumab Ozogamicin at Different Doses in Adult Acute Myeloid Leukemia: Results from the UK NCRI AML16/17 Trials". Blood 126, n. 23 (3 dicembre 2015): 320. http://dx.doi.org/10.1182/blood.v126.23.320.320.
Testo completoAbstract (sommario):
Abstract On behalf of the UK NCRI AML Working Group CD33 was the first target for antibody directed therapy in any cancer with further CD33-directed strategies, including bispecific or chimeric antigen receptors, in development in AML. Our previous meta-analysis results with the first anti-CD33 antibody conjugate Gemtuzumab Ozogamicin (GO) demonstrated the importance of appropriately defining patient subgroups (e.g. by cytogenetics) that may most benefit from this therapy and as such provides a paradigm for other antibody-directed agents. However in adult AML there is limited data on whether CD33 expression levels (for total blasts and any 'immature' CD34+CD38- blasts) contribute to GO response, taking into account the differences of blast CD33 levels associated with specific genetic abnormalities and that CD33 expression level may potentially be a prognostic factor as suggested by the pediatric AML COG study. We evaluated the impact of blast CD33 expression levels on prognosis and GO response in adult AML by central standardised flow cytometric analysis of diagnostic samples from 1364 non-APML patients from the UK NCRI AML16 (older patients, n=334, CD33 expression data not an entry requirement) and AML17 (younger patients, n=1030) trials. Both trials included a GO randomisation (AML16 GO vs not, AML17 3mg vs 6mg vs not first induction); in AML17 all CBF AMLs received GO. CD33 mean fluorescent intensity was quantified for overall blast population (blast CD33 MFI) and CD34+CD38- subset (potentially enriched for leukemic stem cells) (CD33 MFI of CD34+CD38-). Percentage CD33negative blasts of WBC (%CD33neg) was also calculated. Patients were divided into quartiles 1-4 (Q1-4) based on increasing values for each of these parameters. Prevalence of CBF AML (n=152, AML17 only) was inversely associated with high blast CD33 MFI (43% Q1-2, 5% Q4 p<.0001) but MFI levels were also lower for adverse cytogenetics (n=235) (prevalence of non-CBF AML, 55% Q1-2, 10% Q4 p<.0001). Both FLT3 ITD (n=213) and NPM1c (n=322) mutations were more likely to have high (Q3-4) blast CD33 MFI levels even when compared to other intermediate cytogenetic patients (71% of FLT3 ITD in Q3-4 p<.0001; 79% of NPM1c in Q3-4, p<.0001; 40% of non-mutated intermediate in Q3-4). FLT3 ITD and NPM1c were also associated with a low %CD33neg (Q1, <6.5%); FLT3 ITD 37%, NPM1c 43% vs intermediate 20%, CBFs 11%, adverse 16%. In univariate analysis of all patients, higher blast CD33 MFI levels predicted significantly better 5 year OS from entry (Q4 43%, Q2 or 3 36%, Q1 28%, p=0.009): significance was not maintained in analyses adjusted for cytogenetics, FLT3 ITD+, NPM1c, plusage, WBC, performance status, and trial protocol (AML16 vs AML17), although there was an improved CR/CRi (OR 0.81 (0.67-0.97), P=0.02). 321 non-CBF AML patients in our cohort were randomised to GO vs no GO. There was no evidence that CD33 expression levels or percentage of CD33negative blasts or detectable CD33negative CD34+CD38- blasts affected the overall outcome benefit from GO (p=NS for all interactions). There was also no evidence of an interaction between GO treatment and the positive prognostic impact of high CD33. Blast CD33 parameters did not significantly alter outcome in CBF AMLs (all received GO) suggesting that other biological factors are important for CBF GO sensitivity. Interestingly, despite overall lower blast CD33 levels of CBF AMLs, only 1.4% of these had a detectable CD33neg CD34+CD38- immature population of >0.35% of WBC (mean +2SD normal range of CD34+CD38-) compared to 19% of intermediates and 17% of adverse. This might contribute to the effectiveness of GO (and potentially other CD33-directed therapies) in CBF AMLs since clearance of potential LSCs in the CD34+CD38- subset would not be limited by low CD33 expression. For the 270 patients in the AML17 GO dose randomisation, relapse risk was improved by the higher 6mg/m2 dose for patients with a low blast CD33 MFI (Q1) (OR 0.54 (0.26-1.10); p=0.03 for trend) with no increase in 60-day mortality (P=0.4) (Figure). Conclusion Although genetic subgroups have distinct profiles of blast CD33 expression (including low CD33 in both CBF and adverse risk) CD33 levels are not an independent predictor of OS or benefit from GO by adjusted analyses in adult AML. However a higher dose of GO may be more effective at preventing relapse in AMLs with lower blast CD33 expression. These results may be relevant to future CD33-directed strategies. Figure 1. Figure 1. Disclosures Off Label Use: Off Label Use: Gemtuzumab Ozogamicin, an antibody-drug conjugate used to treat AML. Russell:Therakos: Other: shares.
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Dar, RooufUnNabi, S. M. Anas e Mehtab Alam. "Effect of Skew Angle on the Dynamic Response of a Reinforced Concrete Bridge under Blast Loading". Proceedings of the 12th Structural Engineering Convention, SEC 2022: Themes 1-2 1, n. 1 (19 dicembre 2022): 555–61. http://dx.doi.org/10.38208/acp.v1.548.
Testo completoAbstract (sommario):
Accidental explosions and subversive blasts are on rise. The recent devastating Beirut explosion witnesses this fact. Performance of the structures such as bridges in cities and strategic boarder areas is of paramount importance. With this concern the effect of skew angle on the performance of a single span reinforced concrete (RC) bridge deck supported on three symmetrically placed RC girders under blast loading generated by1000kgTNT charge located above and below the mid-section of the central girder at a standoff distance of 0.5 m has been investigated using ABAQUS/CAE. Analyses have been performed at different skew angles i.e. 0º, 10º, 20º, 30º, 40º, and 50º. Several empirical relations from the literature have been used to estimate the blast parameters such as peak overpressure, positive phase duration, the arrival time of blast wave, and decay coefficient. Blast pressure P(t), has been modeled using modified Friedlander’s equation. Distributions of damages have been evaluated with a mesh size of 300 mm using concrete damage plasticity (CDP) model. Maximum displacements have been computed and are compared with those obtained from the provisions of AASHTO: Load Resistance and Factor Design (LRFD) - Bridge Design Specifications (2014). It has been found that the midspan displacement and the stresses of the deck increase for 10º skew angle but decrease for subsequent increase in skew angle for the explosive charge loaded above the mid-section of the central girder. However, tensile as well as compressive damages in girders increase with increase of skew angle irrespective of the location of the blast. Side girders suffer more damage with increase in skew angle than uniform damage for ‘under the deck’ location of explosive charge.
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Lan, Chenchen, Yuejun Hao, Jiannan Shao, Shuhui Zhang, Ran Liu e Qing Lyu. "Effect of H2 on Blast Furnace Ironmaking: A Review". Metals 12, n. 11 (1 novembre 2022): 1864. http://dx.doi.org/10.3390/met12111864.
Testo completoAbstract (sommario):
Under the background of “carbon peaking” and “carbon neutralization”, the green transformation of iron and steel enterprises is imminent. The hydrogen-rich smelting technology of blast furnaces is very important for reducing energy consumption and CO2 emission in ironmaking systems, and it is one of the important directions of green and low-carbon development of iron and steel enterprises. In this paper, the research status of the thermal state, reduction mechanism of iron-bearing burden, coke degradation behavior, and formation of the cohesive zone in various areas of blast furnace after hydrogen-rich smelting is summarized, which can make a more clear and comprehensive understanding for the effect of H2 on blast furnace ironmaking. Meanwhile, based on the current research situation, it is proposed that the following aspects should be further studied in the hydrogen-rich smelting of blast furnaces: (1) the utilization rate of hydrogen and degree of substitution for direct reduction, (2) combustion behavior of fuel in raceway, (3) control of gas flow distribution in the blast furnace, (4) operation optimization of the blast furnace.
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Zhang, Zong-Xian, Li Yuan Chi e Qingbin Zhang. "Effect of Specimen Placement on Model Rock Blasting". Rock Mechanics and Rock Engineering 54, n. 8 (29 aprile 2021): 3945–60. http://dx.doi.org/10.1007/s00603-021-02480-5.
Testo completoAbstract (sommario):
AbstractSmall-scale model blasting plays an important role in understanding mechanism of rock fragmentation by blasting and improving blast technology in rock and mining engineering. Because a specimen (or model) often needs to be placed on either a ground or another material in model blasting, an additional interface appears between the specimen and the ground (or material), compared with an engineering blast that does not have such an interface. In this paper, four model blasts with high-speed photography were presented. The results showed that: (1) as the impedance of a rock specimen was smaller than that of the ground material, the specimen was thrown up and a certain amount of kinetic energy was brought with such a bounce. Thus, this placement should be avoided in model blasts. (2) As a rock specimen was placed on three blocks of the same type of rock as the specimen the specimen was not bounced up during blasting. Correspondingly, no kinetic energy was induced by specimen bounce. Therefore, this placement is recommended for model blasting. If very high specific charge must be used in model blasting, the above-recommended method will not work well due to possible breakage of the base material during blasting. In this case, the rock specimen can be placed on a material with smaller impedance than that of the rock specimen so that specimen bounce can be reduced. Accordingly, such a possible specimen bounce should be estimated by stress wave analysis.
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Yogarajah, Meera, Phuong L. Nguyen, Rong He, Hassan Alkhateeb, Mithun Vinod Shah, Mrinal Mahesh Patnaik, Naseema Gangat et al. "Discrepancy of blast percentage between the bone marrow aspirate and biopsy and its impact on survival outcomes in patients with myelodysplastic syndromes excess blast (MDS-EB)." Journal of Clinical Oncology 37, n. 15_suppl (20 maggio 2019): 7053. http://dx.doi.org/10.1200/jco.2019.37.15_suppl.7053.
Testo completoAbstract (sommario):
7053 Background: The revised International Prognostic Scoring System (IPSS-R) aids in prognosticating MDS. The percentage (%) of blasts in the bone marrow is one of the major determinants of the scoring system. The aspirate blast % is utilized as the standard of care, but there could be discrepancies in the blast % reported by the aspirate and the biopsy. We aim to study the possible use of bone marrow biopsy blasts in MDS-EB in calculating IPSS-R. Methods: The MDS database was reviewed for cases of MDS-EB after due IRB approval. We calculated IPSS-R scores based on the aspirate blast % (IPSS-RAsp) and biopsy blast % (IPSS-RBx). The biopsy blast % was reported morphologically or by the CD34 stain. Whenever a range was reported the highest value was utilized as the blast %. Suboptimal aspirates were excluded from the study. The overall survival (OS) was determined by IPSS-RAsp, IPSS-RBx and IPSS-R highest blast (IPSS-RHi). OS estimates were calculated by Kaplan-Meier curves and log-rank testing using JMP v.13. Uno’s concordance statistic was used to compare all 3 risk scoring systems. Results: Of 1322 patients, 431 (33%) cases were identified with MDS-EB; out of which 173 cases had both blasts reported in the biopsy and the aspirate. Out of 173 cases, 35 (20%) had MDS-EB1, and 61 (35%) had MDS EB-2 based on both biopsy and aspirate (concordant cases). Seventy seven (45%) patients changed from EB-1 to EB2 or vice versa based on the biopsy blast (44/77 (57%) cases were upstaged). The OS outcomes based on the IPSS-RBx biopsy showed a clear and meaningful separation with median OS decreasing with increased risk but IPSS-RAsp and IPSS-RHi did not (Table). We compared the 3 models for observed OS differences using the Uno model and there was no statistically significant difference. Conclusions: IPSS-RBx (but not IPSS-RAsp and IPSS-RHi) identified prognostic groups for OS with median OS decreasing with increased risk. The small sample size may have led to an insignificant effect on model power by Uno model. This finding needs to be validated by other centers. [Table: see text]
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Kohrt, Holbrook E., Samit Patel, Michelle Ho, Terri Owen, Ravindra Majeti, Jason R. Gotlib, Steve Coutre, Bruno C. Medeiros e Ash A. Alizadeh. "Is Time of the Essence in Adult Acute Myeloid Leukemia (AML)? Time to Blast Clearance and Time to Induction Therapy Fail to Predict Overall Survival (OS)." Blood 114, n. 22 (20 novembre 2009): 1617. http://dx.doi.org/10.1182/blood.v114.22.1617.1617.
Testo completoAbstract (sommario):
Abstract Abstract 1617 Poster Board I-643 Background A rapid decline of circulating blasts in response to induction therapy is one of the most important prognostic factors of clinical outcome in childhood acute lymphoblastic leukemia. However, the prognostic significance of time to blast clearance in adult AML has not been well-established. The Mayo Clinic recently reported improved OS with early clearance ('3 days) of peripheral blood (PB) blasts among 86 adult patients with AML. In a separate series, age is suggested to modify the effect of time with shorter interval from diagnosis to induction therapy (TDT) predicting improved OS in younger but not older AML patients. We retrospectively reviewed the Stanford Leukemia Database to validate the prognostic relevance of time and age as a putative effect modifier with respect to OS in AML. Methods From 1993 to 2008 outcomes of 1,909 adult patients with leukemia were reviewed to select eligible patients with previously untreated AML (non-acute promyelocytic leukemia) having received cytarabine-based induction regimens. We defined the day of PB blast clearance (the first day after initiating induction chemotherapy that PB blasts were absent), and three “blast risk groups” (good, intermediate and poor, according to PB blast clearance on or before day 3, on days 4 or 5, or on day 6 or beyond, respectively) identical to the Mayo Clinic model. A 100 cell manual slide differential count was evaluated from the first day of induction through nadir with PB blasts enumerated unless the WBC was less than 0.5 ×109/L. For purposes of TDT analysis, patients receiving therapy on day of diagnosis were excluded (24 patients) as performed in the Cleveland Clinic-MD Anderson (CC-MDA) model. We defined delayed versus immediate treatment (delayed meaning more than 5 days from day of diagnosis to first day of induction therapy) identical to the CC-MDA model. Results Among 333 patients (55% males; median age 53y, range 18-88, including 224 patients<60y) with previously untreated AML, the median and range of white blood cell count (WBC), PB blast percent, and TDT were 10 × 109/L (range: 0.1–332), 23.0% (range: 0–98), and 4 days (range: 0-91) respectively. Karyotype was classified as favorable, intermediate and unfavorable in 9.7%, 59.3% and 31% of cases, respectively. At the time of analysis, 56% had died, primarily of relapse. Median OS was 59 weeks (range: 0-558) in all patients, 76.2 (range: 3.4-558) and 38.3 (range: 0-342) weeks in patients younger than 60 years, and older patients, respectively. The median time to PB blast clearance was six days (range: 1– >11). The distribution of good, intermediate and poor blast risk groups was 28.3%, 26.1%, and 45.6%, without significantly different median OS of 63.8, 56.2, and 51.6 weeks, respectively (Fig 1, p=0.61). In univariate analysis there was no relationship between TDT and OS among all patients as a continuous variable (p=0.791) or classified as delayed versus immediate treatment (Fig 2, p=0.92). When stratified by older and younger AML patients, age did not modify the effect. Conclusion In adults with non-APL AML, both TDT and PB blast clearance after induction chemotherapy with cytarabine-based regimens failed to predict OS. Current practice standards should not be modified until further studies validate the significance of time from diagnosis to treatment and to clearance of circulating blasts. Disclosures No relevant conflicts of interest to declare.
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Ramulu, M., e T. G. Sitharam. "Blast Induced Damage Due to Repeated Vibrations in Jointed Gneiss Rock Formation". International Journal of Geotechnical Earthquake Engineering 1, n. 1 (gennaio 2010): 110–34. http://dx.doi.org/10.4018/jgee.2010090807.
Testo completoAbstract (sommario):
Blasting is the most common method of rock excavation technique in mining and civil construction and infrastructure projects. Rock blasting produces seismic waves similar to those produced by earthquakes, but with relatively high frequency and low amplitude. General blast induced damage was extensively studied by researchers globally, but the studies on damage due to repeated blast vibrations is not yet reported, quantitatively, on underground openings. This paper deals with the research work carried on the effect of repeated dynamic loading imparted on the jointed rock mass from subsequent blasts in the vicinity, on the jointed rock mass at Lohari Nag Pala Hydroelectric Power Construction Project. The blast induced damage was monitored by borehole extensometers, borehole camera inspection surveys and triaxial geophones installed at three test sites of different joint orientations at the Main Access Tunnel of power house. The study reveals that there was extra damage of 60%, exclusively due to repeated blast vibrations. The results of the study indicate that repeated dynamic loading, resulted in damage even at 33% of the conventional damage threshold vibrations (Vc) in case of favorable joint orientations and 23% of Vc in case of unfavorable joints. The paper concludes in quantification of effect of repeated blast loading and the orientation of joints on the extension of damage zone in jointed rock mass of underground excavations.
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Gao, Qidong, Wenbo Lu, Zhendong Leng, Zhaowei Yang, Yuzhu Zhang e Haoran Hu. "Effect of Initiation Location within Blasthole on Blast Vibration Field and Its Mechanism". Shock and Vibration 2019 (6 dicembre 2019): 1–18. http://dx.doi.org/10.1155/2019/5386014.
Testo completoAbstract (sommario):
In drill and blast, the explosive filled in each blasthole is cylindrically shaped and generally initiated by the detonator. Thus, the effect of the initiation location must be addressed, as it determines the detonation direction along the entire column explosive. In this paper, the effect of the initiation location on blast vibration field and its acting mechanism were comprehensively investigated through the theoretical, computational, and experimental approaches. The results indicate that the initiation location plays an important role in the blast vibration filed of the cylindrical charge. The underlying effect of the initiation location can be regarded as the combined results of the energy distribution and phase delay effects of the column explosive source. The behavior of the rock mass in the single-hole blasting experiment demonstrates that the explosion energy is preferentially transmitted to the forward direction of the detonation wave. The seed wave-based computation model verifies that owing to the phase delay effect, the blast vibration field of the cylindrical charge is not uniformly distributed and is strengthened at the forward direction of the detonation wave. The production blasting experiment indicates that the ground PPV under bottom initiation is 61.3%∼211.7% larger than that under top initiation. In addition, the effect of the initiation location is sensitive to the charge length L and the denotation velocity D. Meanwhile, the effect of the initiation location vanishes with distance. The present study provides valuable reference for understanding the effect of the initiation location on blast vibration in drill and blast.
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Gonen, Alper. "Investigation of Fault Effect on Blast-Induced Vibration". Applied Sciences 12, n. 5 (22 febbraio 2022): 2278. http://dx.doi.org/10.3390/app12052278.
Testo completoAbstract (sommario):
The propagation of blast-induced vibration velocity in the rock mass varies depending on many parameters. Due to a large number of effective parameters and the variability in the rock mass environment, it is not possible to create a vibration velocity propagation model using all of these parameters. On the other hand, it is important to determine the blast vibration velocity level in urban infrastructure works and mining operations near settlements. Recent studies on the subject have been interested in the determination of blast-induced vibration velocity by the back analysis estimations of advanced statistical approaches and artificial intelligence approaches. However, sudden changes in rock mass properties such as fault zones cause significant errors in the advanced statistical approaches functions used at the level of blast-induced vibration velocity. In this study, the variation of the blast-induced vibration velocities under the influence of the fault zone has been discussed. There is a fault zone along the northwest line of the Quarry boundary. The influence of the fault zone on the blast-induced vibration propagation was determined by comparing the vibration velocities behind the fault zone with the vibration velocities in the non-fault zone. Accordingly, it has been concluded that the fault zone has the potential to create significant differences due to the reflection/refraction of surface waves (Rayleigh and Love waves) in vibration velocity values in areas close to the fault zone have the potential.
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Li, Zhi Zhong, De Gao Tang, Zheng Liu, Yu Long Xue e Wei Wei Li. "Numerical Analysis on Protective Effectiveness of Composite Blast Walls against Blast Wave". Advanced Materials Research 850-851 (dicembre 2013): 368–72. http://dx.doi.org/10.4028/www.scientific.net/amr.850-851.368.
Testo completoAbstract (sommario):
For the comparative analysis of composite blast walls on the protective effects of blast wave, Overpressure protective effectiveness coefficient was put forward to analyze protective effectiveness and . It was studied that Protective effectiveness of composite blast walls under blast waves using 3D numerical simulation method and analysis of the amount of drugs, explosive distance, height and other structural parameters on protective effect of composite structures. The influence of several factors on forecasting formula was analyzed, such as scaled blast distance and scaled height of wall. Via fitting the simulation results overpressure formula of the back of composite blast walls was obtained. The result indicate that protective effectiveness of composite structure increases when walls height increases or scaled blast distance decreases.
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Zhang, Rui, Weibo Huang, Ping Lyu, Shuai Yan, Xu Wang e Jiahui Ju. "Polyurea for Blast and Impact Protection: A Review". Polymers 14, n. 13 (30 giugno 2022): 2670. http://dx.doi.org/10.3390/polym14132670.
Testo completoAbstract (sommario):
Polyurea has attracted extensive attention from researchers and engineers in the field of blast and impact protection due to its excellent quasi-static mechanical properties and dynamic mechanical properties. Its mechanical properties and energy absorption capacity have been tuned by means of formulation optimization, molecular dynamics (MD) simulation and the addition of reinforcing materials. Owing to the special molecular structure of polyurea, the mechanism of polyurea protection against blasts and impacts is the simultaneous effect of multiple properties. For different substrates and structures, polyurea needs to provide different performance characteristics, including adhesion, hardness, breaking elongation, etc., depending on the characteristics of the load to which it is subjected. The current article reviews relevant publications in the field of polyurea blast and impact protection, including material optimization, protection mechanisms and applications in blast and impact protection.
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Stewart, Mark G., Michael D. Netherton e Hayden Baldacchino. "Observed airblast variability and model error from repeatable explosive field trials". International Journal of Protective Structures 11, n. 2 (26 agosto 2019): 235–57. http://dx.doi.org/10.1177/2041419619871305.
Testo completoAbstract (sommario):
Explosive field trials have been conducted to measure the peak incident pressure, impulse and time of positive phase duration following the detonation of 15 different masses of the Plastic Explosive No #4. A novel aspect of these field trials was the repeatability of tests. Eight pressure gauges collected data during each blast, and at each scaled distance. In all, 4 blasts were conducted for each scaled distance (i.e. up to 32 measurements recorded for each scaled distance) – 60 blasts were fired in total. Consequently, this repeatability of testing allowed the mean and variance of blast pressure–time histories to be quantified, with a view to better characterise the variability of a blast itself and model error variability. This article describes the explosive field trials, and the statistical analysis of blast load variability and model error for peak incident pressure, impulse and time of positive phase duration. It was found that the mean model error is close to unity with a coefficient of variation of up to 0.15 for pressure and 0.21 for impulse. The lognormal probability distribution best fits the model error data. The probabilistic models derived from these tests can be used for a variety of structural engineering applications, such as calculating reliability-based design load or partial safety factors for explosive blast loading, and estimating the probability of damage and casualties for infrastructure subject to explosive blast loading. This is illustrated for a terrorist explosive scenario involving a spherical free-air burst, where the damage modes of interest are breaching and spalling of a concrete slab. It was found that the variability of charge mass, range and model error have a significant effect on reliability-based design.
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van Oudenallen, R. G., P. Verbraak, H. A. M. Geerdes e M. G. O. Klaassen. "Blast furnace circumferential process symmetry: effect of flow distribution in hot blast systems". Ironmaking & Steelmaking 38, n. 7 (ottobre 2011): 489–93. http://dx.doi.org/10.1179/030192311x13135947813979.
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Michaux, J. L., F. Naaim-Bouvet, M. Naaim, M. Lehning e G. Guyomarc’h. "Effect of unsteady wind on drifting snow: first investigations". Natural Hazards and Earth System Sciences 2, n. 3/4 (31 dicembre 2002): 129–36. http://dx.doi.org/10.5194/nhess-2-129-2002.
Testo completoAbstract (sommario):
Abstract. Wind is not always a steady flow. It can oscillate, producing blasts. However, most of the current numerical models of drifting snow are constrained by one major assumption: forcing winds are steady and uniform. Moreover, very few studies have been done to verify this hypothesis, because of the lack of available instrumentation and measurement difficulties. Therefore, too little is known about the possible role of wind gust in drifting snow. In order to better understand the effect of unsteady winds, we have performed both experiments at the climatic wind tunnel at the CSTB (Centre Scientifique et Technique des Bâtiments) in Nantes, France, and in situ experiments on our experimental high-altitude site, at the Lac Blanc Pass. These experiments were carried out collaboratively with Cemagref (France), Météo-France, and the IFENA (Switzerland). Through the wind tunnel experiments, we found that drifting snow is in a state of permanent disequilibrium in the presence of fluctuating airflows. In addition, the in situ experiments show that the largest drifting snow episodes appear during periods of roughly constant strong wind, whereas a short but strong blast does not produce significant drifting snow. Key words. Drifting snow, blowing snow, gust, blast, acoustic sensor
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Zheng, Zejun, Jun Yu, Fangfang Wei e Jun Wu. "Numerical study of blast performance of concrete filled double-steel-plate composite walls". International Journal of Protective Structures 11, n. 1 (2 maggio 2019): 23–40. http://dx.doi.org/10.1177/2041419619845010.
Testo completoAbstract (sommario):
Currently, terrorism attack is one of the main concerns in public safety, although the probability of such attack is fairly low. From the perspective of multi-hazard mitigation, it is expected that the structural members that are used to resist earthquakes or winds in buildings should also reduce the vulnerability to blast. Concrete filled double-steel-plate composite walls are one of the novel structural members which are used as shear walls, in which concrete is filled between two steel plates and connected to them through shear studs. In this article, finite-element-based analyses were carried out to investigate the dynamic behaviour of concrete filled double-steel-plate composite walls subjected to blast loading. A three-dimensional numerical model was developed and validated based on previously published experimental results. Then, the numerical models were employed to investigate the effects of axial compression ratio, concrete strength, wall thickness and shear connector spacing on the blast performance of concrete filled double-steel-plate composite walls under different blast intensities. The results show that axial compression has both positive and negative effects on the blast performance of concrete filled double-steel-plate composite walls. The positive effect prevails due to increased effective flexural stiffness when plastic deformation under zero axial compression and the same blast load is marginal, whereas the negative effect is more dominant due to P-delta effect when evident plastic deformation occurs under zero axial compression and the same blast load.
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Schwartz, Cindy L., E. Brad Thompson, Richard D. Gelber, Mary L. Young, David Chilton, Harvey J. Cohen e Stephen E. Sallan. "Improved Response With Higher Corticosteroid Dose in Children With Acute Lymphoblastic Leukemia". Journal of Clinical Oncology 19, n. 4 (15 febbraio 2001): 1040–46. http://dx.doi.org/10.1200/jco.2001.19.4.1040.
Testo completoAbstract (sommario):
PURPOSE: We investigated whether there was a dose-response relationship for the use of corticosteroids in childhood acute lymphoblastic leukemia (ALL). PATIENTS AND METHODS: Three hundred sixty-nine patients, ages 1 to 18 years with ALL, were randomly assigned to receive one of four different doses of corticosteroid (prednisolone 40 mg/m2/d or dexamethasone 6, 18, or 150 mg/m2/d) administered as a 3-day, single-drug window before initiation of standard, multidrug induction chemotherapy. Corticosteroid drug response was measured by reduction in bone marrow blast counts and absolute peripheral blast counts after 3 days. Glucocorticoid receptor (GCR) number and the effective concentration of dexamethasone resulting in a 50% reduction of leukemic cell viability in vitro (EC-50) were evaluated at days 0 and 3. RESULTS: Increasing dexamethasone doses resulted in greater marrow blast response (P = .007), with a similar trend in peripheral-blood blast response. High-dose corticosteroid regimens (dexamethasone 18 or 150 mg/m2/d) elicited better responses than standard doses of dexamethasone or prednisone (bone marrow, P = .002; peripheral blasts, P = .05). Among patients treated with standard-dose corticosteroids, 38% with resistant (EC-50 > 10-7) peripheral blasts had a good response compared with 92% with sensitive (EC-50 < 10-7) peripheral blasts (P = .01). In contrast, there was no differential response according to EC-50 group after high-dose corticosteroids. Similarly, an association between response and GCR on peripheral-blood blasts was noted after standard-dose corticosteroid regimens but not after high-dose corticosteroid regimens. CONCLUSION: Response of ALL to glucocorticoid therapy increased with dose. Higher-dose corticosteroid treatment abrogated the effect of relative drug insensitivity and of low GCR on peripheral blasts.
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Yan, Bing, Ming Liu, Qingsheng Meng, Yao Li, Shenggui Deng e Tao Liu. "Study on the Vibration Variation of Rock Slope Based on Numerical Simulation and Fitting Analysis". Applied Sciences 12, n. 9 (21 aprile 2022): 4208. http://dx.doi.org/10.3390/app12094208.
Testo completoAbstract (sommario):
In engineering blasting, the slope surfaces in the blasting area exert various effects on the blast vibration velocity. For example, the slope effect and the whipping effect are generated in the slope area, which will influence the blast vibration velocity. The slope area is the key protection area for many projects; therefore, it is of practical value to explore the influence of slope surface on blast vibration speed for the prediction of blast vibration and protection against it. The influence of slope effect and whipping effect on blast vibration velocity in the slope area was analyzed by numerical simulation and fitting. The field monitoring data were fitted to the blast vibration velocity prediction formula. According to the obtained fitting formula, we inferred that vibration speed amplification occurred in the slope area. Numerical simulation was carried out using the ANSYS/LS-DYNA program. Using the above two methods, whether the slope effect and whip tip effect occurred in the study area was verified. By numerical simulation, we established three-dimensional (3D) slope models for four different working conditions. We simulated the complete blasting process and the consistency between the simulation results, and the field data proved the reliability of the numerical simulation. Based on the results of the numerical simulation, we explored the variation of blasting vibration velocity under different height difference conditions. Finally, we explored the distribution law of blasting vibration at the slope surface and inside the slope.
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Ma, Qin-yong, Pu Yuan, Jing-shuang Zhang, Rui-qiu Ma e Bo Han. "Blast-Induced Damage on Millisecond Blasting Model Test with Multicircle Vertical Blastholes". Shock and Vibration 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/504043.
Testo completoAbstract (sommario):
To investigate the blast-induced damage effect on surrounding rock in vertical shaft excavation, 4 kinds of millisecond blasting model tests with three-circle blastholes were designed and carried out with excavation blasting in vertical shaft as the background. The longitudinal wave velocity on the side of concrete model was also measured before and after blasting. Then blast damage factor was then calculated by measuring longitudinal wave velocity before and after blasting. The test results show that the blast-induced damage factor attenuated gradually with the centre of three-circle blastholes as centre. With the threshold value of 0.19 for blast-induced damage factor, blast-induced damage zones for 4 kinds of model tests are described and there is an inverted cone blast-induced damage zone in concrete model. And analyses of cutting effect and blast-induced damage zone indicate that in order to minimize the blast-induced damage effect and ensure the cutting effect the reasonable blasting scheme for three-circle blastholes is the inner two-circle blastholes initiated simultaneously and the outer third circle blastholes initiated in a 25 ms delay.
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Makovička, Daniel, e Daniel Makovička. "Structure Analysis Loaded by Interior Blast Effect". Applied Mechanics and Materials 617 (agosto 2014): 86–91. http://dx.doi.org/10.4028/www.scientific.net/amm.617.86.
Testo completoAbstract (sommario):
The paper determines the parameters of the explosion wave excited by a terrorist charge and assumption of the building structure of a railway station based on dynamic analysis. Certain simplified methods according to various publications, according to our own experimental results and according to 3D computations based on detailed calculation modelling of the interior of the room are compared to determine the explosive effects. Equivalent static analysis was applied to the dynamic response of the structural elements of the selected room. The damage caused to these structural elements is weighted on the basis of the angle of failure of the central axis / surface, and on the basis of the limit stress state of these structures.
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Tolani, Sunita, Shiv Dayal Bharti, Mahendra Kumar Shrimali e Tushar Kanti Datta. "Effect of Surface Blast on Multistory Buildings". Journal of Performance of Constructed Facilities 34, n. 2 (aprile 2020): 04020015. http://dx.doi.org/10.1061/(asce)cf.1943-5509.0001415.
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Gladkov, N. A., S. A. Nikolaev e L. G. Budnik. "Effect of alkalis on blast-furnace smelting". Metallurgist 30, n. 2 (febbraio 1986): 44–46. http://dx.doi.org/10.1007/bf01140958.
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Li, Yan, Tingfang Jian, Tongxiang Ma, Meilong Hu, Leizhang Gao e Yu Yang. "Effect of titanium on the skull formation of the blast furnace hearth". Metallurgical Research & Technology 117, n. 4 (2020): 409. http://dx.doi.org/10.1051/metal/2020042.
Testo completoAbstract (sommario):
The erosion of the blast furnace hearth has become one of the key factors affecting the life of the blast furnace, because of the limited on-line monitoring and control means in the blast furnace hearth area, the burn-through accidents of the blast furnace hearth and bottom occur occasionally. In this work, based on the self-built platform of heat flow regulation, the control mechanism of the high melting phases of TiC is studied. The on-line control mechanism of the hearth erosion by adding titanium-containing materials was discussed. There are three steps for the on-line control of iromaking using titanium-containing materials in blast furnace. Firstly, Ti(C, N) precipitated from the molten iron due to the decrease of temperature in the erosion zone of the hearth. Secondly, the viscosity of the molten iron increased with the precipitation of Ti(C, N) in the erosional cryogenic zone and temperature further decreasing. Finally, the protective layer, included pig iron matrix and Ti(C, N) solid fulcrum, formed because of the solidification of the molten iron. The protective layer can replace the corroded lining of the blast furnace to prevent its hearth from being eroded.
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Yu, Xiao, Li Chen, Qin Fang, Xiaofeng Hou e Yi Fan. "Blast mitigation effect of the layered concrete structure with an air gap: A numerical approach". International Journal of Protective Structures 9, n. 4 (3 maggio 2018): 432–60. http://dx.doi.org/10.1177/2041419618766951.
Testo completoAbstract (sommario):
A novel layered concrete structure with an air gap was proposed to resist explosion attacks from terrorist bombings or conventional weapons. The proposed layered structure potentially benefits mitigating the blast wave induced from detonation in the predamaged concrete shelter layer by projectile penetration, because the wave impedance between air and concrete material is far different. To quantitatively evaluate the blast mitigation effects and reveal the blast-resistant mechanism, a fine numerical model of the proposed layered structure was built in LS-DYNA, in which trinitrotoluene explosive was detonated in predamaged concrete shelter at different depths. The developed model was validated by field tests of concrete slab under contact explosion. Failure mode of concrete shelter and pressure time histories on the protective structure layer were captured and compared. The distinct blast mitigation effect of the proposed layered structure was demonstrated. A parametric study on the perforation limit, height, and residual depth of concrete shelter was also performed. The calculated results revealed that trinitrotoluene explosive detonated at the impact perforation limit of concrete shelter by projectile penetration is a dangerous critical condition that may cause negative effects on blast mitigation. The blast mitigation rates can always exceed 99%, as long as the concrete shelter is not blasted to perforation. A fitting formula to obtain a higher blast mitigation rate in guiding the design of a layered concrete structure with an air gap was put forward.
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LeFor, A. T., A. Eisenthal e S. A. Rosenberg. "Heterogeneity of lymphokine-activated killer cells induced by IL-2. Separate lymphoid subpopulations lyse tumor, allogeneic blasts, and modified syngeneic blasts." Journal of Immunology 140, n. 11 (1 giugno 1988): 4062–69. http://dx.doi.org/10.4049/jimmunol.140.11.4062.
Testo completoAbstract (sommario):
Abstract Murine splenocytes incubated for 3 to 4 days with the lymphokine, IL-2, acquire the ability to mediate the lysis of a wide variety of fresh tumor targets in short term chromium release assays. We undertook these studies to examine the lysis of splenocyte blasts by these lymphokine-activated killer (LAK) cells, to help gain an understanding of the mechanisms of target cell recognition. Allogeneic blast targets but not syngeneic blasts are highly lysable by LAK effector cells. By using congenic mice, we have shown that only the H-2 haplotype, and not other differences, determines the recognition and lysis of a blast target cell. Both Con A- and LPS-induced allogeneic splenocyte blasts are lysed and thus lectin-induced binding of effectors and targets is unlikely to be responsible for this effect. By using in vivo antibody depletion experiments, we showed that different populations of effector cells mediate the lysis of tumor cells and allogeneic blasts. Furthermore, we observed that the lysis of a susceptible blast can be inhibited only by like cold blasts of the same haplotype. These results suggest that there is a separate population of LAK cells responsible for the lysis of each type of blast target cell. Though syngeneic blasts were not lysed by LAK cells, TNP modification of syngeneic blasts converted them into cells that were recognized and lysed by LAK cells. In cold target inhibition studies, the lysis of fresh syngeneic tumor was not inhibited by TNP-modified syngeneic blasts. Similarly, the lysis of TNP-modified syngeneic blasts was not inhibited by fresh tumor. By using in vitro antibody depletion, we determined that TNP-modified blasts are lysed by LAK cells with Thy-1+ precursors, in distinction to the Thy-1- precursors involved in tumor cell lysis. Elimination of the Thy-1+ cells at the precursor stage completely abrogated the lysis of blasts but did not diminish the lysis of tumor cells. We conclude that IL-2 promotes the growth of numerous populations of effector cells with Thy-1+ precursors that have a narrow range of specificity, in contrast to the broad lytic ability for fresh tumor mediated by LAK cells with Thy-1- precursors.
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De Stefano, V., L. Teofili, S. Sica, S. Mastrangelo, A. Di Mario, S. Rutella, P. Salutari, C. Rumi, G. d'Onofrio e G. Leone. "Effect of all-trans retinoic acid on procoagulant and fibrinolytic activities of cultured blast cells from patients with acute promyelocytic leukemia". Blood 86, n. 9 (1 novembre 1995): 3535–41. http://dx.doi.org/10.1182/blood.v86.9.3535.bloodjournal8693535.
Testo completoAbstract (sommario):
The mechanisms underlying acute promyelocytic leukemia (APL) coagulopathy and its reversal by administration of all-trans retinoic acid (ATRA) have been investigated. Bone marrow promyelocytic blasts from nine patients with APL were cultured with or without ATRA 1 mumol/L. Cultured blasts (days 0, 3, 6, and 9) were washed, resuspended in phosphate buffer, lysed by freezing and thawing, and then assayed for procoagulant activity (PCA), elastase activity, tissue factor (TF) antigen, tissue-type plasminogen activator (t-PA) antigen and urokinase- type plasminogen activator (u-PA) antigen. PCA was determined by a recalcification assay. Elastase was measured by an amidolytic assay (S- 2484). TF, t-PA, and u-PA antigens were measured by an enzyme-linked immunosorbent assay (ELISA). Malignant promyelocytes isolated from the patients had increased levels of PCA and TF as compared with the control polymorphonucleates, and low levels of elastase, t-PA, and u- PA; the patient blast PCA level was significantly related to the degree of hypofibrinogenemia. In this system, blast PCA depended on the tissue factor and was significantly correlated to the TF antigen values. In the cultures without ATRA, PCA, TF, and u-PA progressively increased, whereas elastase and t-PA levels remained essentially unchanged. In the presence of ATRA, all parameters (except u-PA) decreased during the culture time. Thus, a major role of the promyelocytic blast cell PCA in the pathogenesis of M3-related coagulopathy is suggested; the ATRA effect on coagulopathy seems mainly mediated by a downregulation of the PCA.
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Alterman, Dariusz, Mark G. Stewart e Michael D. Netherton. "Probabilistic assessment of airblast variability and fatality risk estimation for explosive blasts in confined building spaces". International Journal of Protective Structures 10, n. 3 (15 maggio 2019): 306–29. http://dx.doi.org/10.1177/2041419619849083.
Testo completoAbstract (sommario):
Explosive blasts in confined building spaces, such as lobbies or foyers, can amplify blast loads. This article uses the computational fluid dynamics model ProsAir to estimate blast loads in a typical ground floor lobby of a commercial or government building. Monte-Carlo simulation is used to probabilistically model the effect that variability and uncertainty of charge mass and location, net equivalent quantity factor, temperature, atmospheric pressure and model errors have on airblast variability. The analysis then calculates the probability of casualties due to the effects of pressure and impulse, where human vulnerability due to the effects of pressure and impulse is a function of lung rupture, whole-body displacement or skull fracture (or the combination of the three). The terrorist threats considered are improvised explosive devices ranging in mass from 5 kg (backpack bomb) to 23 kg (suitcase bomb) detonated in various locations inside the building. As expected, blast pressure and fatality risks are dependent on the type of facade glazing (e.g. vulnerable glazing allows venting of the blast), improvised explosive device size and location. It was found that the mean fatality risk for a 23 kg terrorist improvised explosive device is 8.6%, but there is a 5% chance that fatality risks can exceed 20%. It was also found that a probabilistic analysis yielded lower mean fatality risks than a deterministic analysis. The effect of venting was also significant. Mean fatality risks increased by up to 10-fold if there was no venting (i.e. a bunker-like structure without windows), but reduced by about 30% for a fully vented structure (i.e. no windows). This probabilistic analysis allows decision-makers to be more aware of terrorism risks to building occupants, and how improved building design and security measures may ameliorate these risks.
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Hung, Cheng-Wei, Ying-Kuan Tsai, Tai-An Chen, Hsin-Hung Lai e Pin-Wen Wu. "Numerical Study of Pressure Attenuation Effect on Tunnel Structures Subjected to Blast Loads". Applied Sciences 11, n. 12 (18 giugno 2021): 5646. http://dx.doi.org/10.3390/app11125646.
Testo completoAbstract (sommario):
This study used experimental and numerical simulation methods to discuss the attenuation mechanism of a blast inside a tunnel for different forms of a tunnel pressure reduction module under the condition of a tunnel near-field explosion. In terms of the experiment, a small-scale model was used for the explosion experiments of a tunnel pressure reduction module (expansion chamber, one-pressure relief orifice plate, double-pressure relief orifice plate). In the numerical simulation, the pressure transfer effect was evaluated using the ALE fluid–solid coupling and mapping technique. The findings showed that the pressure attenuation model changed the tunnel section to diffuse, reduce, or detour the pressure transfer, indicating the blast attenuation effect. In terms of the effect of blast attenuation, the double-pressure relief orifice plate was better than the one-pressure relief orifice plate, and the single-pressure relief orifice plate was better than the expansion chamber. The expansion chamber attenuated the blast by 30%, the one-pressure relief orifice plate attenuated the blast by 51%, and the double-pressure relief orifice plate attenuated the blast by 82%. The blast attenuation trend of the numerical simulation result generally matched that of the experimental result. The results of this study can provide a reference for future protective designs and reinforce the U.S. Force regulations.
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Nawar, Mahmoud, Alaa Ata, Marwa Nabil e Sally Hassan. "Numerical analysis of underground tunnels subjected to surface blast loads". Frattura ed Integrità Strutturale 15, n. 55 (28 dicembre 2020): 159–73. http://dx.doi.org/10.3221/igf-esis.55.12.
Testo completoAbstract (sommario):
The increased terrorist attacks on important public structures and utilities have raised the vital necessity for the investigation of performance of structures under blast loads to improve the design and enhance the behavior of structures subjected to such threats. In this study, 3-D finite element analysis is used to study the effect of surface explosions on the response of RC bored tunnels. The soil behavior is modelled using Drucker-Prager Cap model. Two types of soil are investigated, and the blast load is considered through various weights of TNT explosive charges at heights of 0.50 m and 1.0 m from ground surface. To study the effect of horizontal standoff distance, six different horizontal distances are considered. The results show that the soil type has a significance effect on tunnel response due to surface blasts. Also the weight and the location of charge have a great effect on the safety of the tunnel. Finally, a parametric study is established to define the borders of the restricted area around the tunnel location to be safe.
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Qin, Tiange, Mingze Wu, Lin Jia, Lingli Xie e Li Wu. "Effects of Vibration on Adjacent Pipelines under Blasting Excavation". Applied Sciences 13, n. 1 (22 dicembre 2022): 121. http://dx.doi.org/10.3390/app13010121.
Testo completoAbstract (sommario):
Exploring a pipeline’s response to blast vibration during tunnel excavation is critical for ensuring the safety of the pipeline. In this paper, the vibration monitoring and numerical simulation methods are used to evaluate the dynamic response of ground soil and pipelines to blasts. The attenuation law of peak particle velocity (PPV) and the distribution characteristics of peak effective stress (PES) in pipe sections under different working conditions are studied. The following findings are recorded: (1) A three-dimensional model considering in situ stress is established, and it is found the triangular equivalent load simulation blast effect method used in this paper can effectively reflect the impact of blasting on pipelines. The simulation error is controlled at 7.69%. (2) The ground PPV of each monitoring point decays continuously with the increase in horizontal and axial distance, and the cavity enlargement effect is exhibited above the excavation area. The oncoming blast side PPV of the pipe section is more significant than that behind the blast side. (3) When the blast vibration is transmitted to the pipe, there are differences in the PPV and PES distribution characteristics across the pipe cross-section. The PPV is greater in the lower part of the pipe section, while the PES value is greater in the upper part of the pipe section. The maximum PES of 1.53 MPa is significantly lower than the safety threshold (≤4.6 MPa) at the hazardous-section-monitoring point. (4) A pipeline PPV prediction model is proposed to guide subsequent blasting program development. An empirical formula for the safety criterion applicable to this study is proposed for the scientific implementation of safety assessments for subsequent construction. This safety evaluation framework can be used as a reference for similar projects.
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Kozyrev, S. A., E. A. Vlasova, A. V. Sokolov e E. A. Usachev. "Evaluation of the efficient application of «Iskra-T» electronic initiating devices in terms of crushing and seismic action of face blasts". Mining Industry Journal (Gornay Promishlennost), n. 2/2021 (10 maggio 2021): 107–13. http://dx.doi.org/10.30686/1609-9192-2021-2-107-113.
Testo completoAbstract (sommario):
The paper justifies the optimal delay time in non-synchronous fan blasting with the most optimal delay time between the holes being 15 ms. Experiments were conducted to assess the breaking conditions and seismic effects of face blasts in the underground conditions of the Rasvumchorrsky mine using the Iskra-T electronic initiating systems with delay times of 10, 15 and 20 ms. With the delay times of 10 and 15 ms there is no clear segregation of the blast stages and interference of compression waves, created by consecutively blasted charges, takes place, while their joint interaction leads to insignificant increase of the seismic effects on the mine workings. According to the results of ore drawing monitoring, the number of boulders with the above delay times did not exceed 10 pieces for the whole blasted volume for each round. With the delay time of 20 ms a clear segregation of the blast stages was obtained with the minimum number of 7 boulders per blast. In order to ensure acceptable rock mass fragmentation quality and reduce the seismic effect of blasting on the mine workings, as well as to preserve the pilot holes drilled, it is advisable to use reverse initiation with non-synchronized fan blasting with the delay time of 20 ms between the holes.
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Joshi, Rishabh, e Associate Professor. "Transient Effect of Blast Loads on RCC Building". Asian Review of Civil Engineering 8, n. 1 (5 maggio 2019): 9–19. http://dx.doi.org/10.51983/tarce-2019.8.1.2286.
Testo completoAbstract (sommario):
The increase in the number of terrorist attacks has shown that the effect of blast loading on structures is a serious matter that should be taken into consideration in the design process. The blast pressure on the structure due to nearby explosion is of very high magnitude and very short duration. Such an impulsive loading requires dynamic time-history analysis. This paper describes the nature of explosion of explosive materials and dynamic pressure developed on the nearby structure in lieu of explosion. Initially, efforts have been made to determine the effect of 1000 kg of C4 explosive material as an equivalent weight of TNT on different surfaces of a building model at a stand-off distance of 22.5m. The intensity of blast load on each surface is analytically determined as a record of pressure time history. Further attempts have been made to determine the effect of distance of blast for the same explosive material on building surfaces at stand-off distance of 10m, 18.5m, 22.5m and 27m. The effect of different explosives, i.e., TNT, C4, RDX and PETN on building surfaces at constant stand-off distance of 22.5m has also been determined. From the analysis, it is observed that the effect of blast load on front and rear surface of the building is critical. For close range explosions, deformations on front surface are more but with increase in stand-off distance, maximum deformations occur in roof surface.
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Elnasri, Ibrahim, e Han Zhao. "Impact Response of Sacrificial Cladding Structure with an Alporas Aluminum Foam Core Under Blast Loading". International Journal of Applied Mechanics 12, n. 08 (settembre 2020): 2050094. http://dx.doi.org/10.1142/s1758825120500945.
Testo completoAbstract (sommario):
This paper presents numerical and analytical studies of the response of a sacrificial cladding structure with an Alporas aluminum foam core and a thick mild steel cover and rear plates under blast loading. A suitable numerical model in LS-DYNA based on the coupled Load Blast Enhanced/Multi-Material Arbitrary Lagrangian–Eulerian (LBE/MM-ALE) methods is selected and validated using the experimental data available in the literature. The shock front propagation and micro-inertia effects are responsible for the strength enhancement predicted in the virtual blast test. Two models with different decaying blast loading functions are examined to study the fluid–structure interaction (FSI) effect. The simulation results show that the FSI effect is negligible if the foam core is strain-rate insensitive. Further investigations should be conducted with analytical models if the core material of the sacrificial cladding structures exhibits a strong strain-rate effect (for example, Alporas foam).
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Hoang, T., A. Haman, O. Goncalves, GG Wong e SC Clark. "Interleukin-6 enhances growth factor-dependent proliferation of the blast cells of acute myeloblastic leukemia". Blood 72, n. 2 (1 agosto 1988): 823–26. http://dx.doi.org/10.1182/blood.v72.2.823.823.
Testo completoAbstract (sommario):
Abstract The effects of recombinant interleukin-6 (IL-6) on the proliferation of blast precursors present in the peripheral blood of patients with acute myeloblastic leukemia (AML) was investigated. IL-6 had little effect by itself; however, it synergized with granulocyte macrophage colony- stimulating factor (GM-CSF) and interleukin-3 (IL-3) in the stimulation of AML blast colony formation. Responsiveness of blast progenitors to IL-6 was heterogeneous. On normal bone marrow cells the same synergy was observed on granulocyte and monocyte precursors (GM-CFC), while there was no significant effect on erythroid and multipotential precursors.
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Hoang, T., A. Haman, O. Goncalves, GG Wong e SC Clark. "Interleukin-6 enhances growth factor-dependent proliferation of the blast cells of acute myeloblastic leukemia". Blood 72, n. 2 (1 agosto 1988): 823–26. http://dx.doi.org/10.1182/blood.v72.2.823.bloodjournal722823.
Testo completoAbstract (sommario):
The effects of recombinant interleukin-6 (IL-6) on the proliferation of blast precursors present in the peripheral blood of patients with acute myeloblastic leukemia (AML) was investigated. IL-6 had little effect by itself; however, it synergized with granulocyte macrophage colony- stimulating factor (GM-CSF) and interleukin-3 (IL-3) in the stimulation of AML blast colony formation. Responsiveness of blast progenitors to IL-6 was heterogeneous. On normal bone marrow cells the same synergy was observed on granulocyte and monocyte precursors (GM-CFC), while there was no significant effect on erythroid and multipotential precursors.
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Han, Feng, Han Zhang, Yang Hu e Xu Yao Bai. "Experimental Studies on Explosion Effect in Typical Cavity Underground". Advanced Materials Research 368-373 (ottobre 2011): 2895–99. http://dx.doi.org/10.4028/www.scientific.net/amr.368-373.2895.
Testo completoAbstract (sommario):
In this paper, the design of the single cuboids cavity model of cavity is on the basis of national defense works and human defense works design specifications, with which to get the distribution of blast load on the wall of typical cavity and the destroy model. In experiment, we added the mass of explosive until the construction is destroyed. Data of pressure-time curve of blast load and acceleration-time curve of the structure wall vibration are used to analyze the distribution of blast load and the destruction form of structure, and to be the basis of further research on other kinds of underground cavity.
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Kuendgen, Andrea, Corinna Strupp, Kathrin Nachtkamp, Barbara Hildebrandt, Rainer Haas, Norbert Gattermann e Ulrich Germing. "Varying Importance of Prognostic Factors in Subgroups of Myelodysplastic Syndromes Defined by Blast Count, Cytogenetic Risk Group, or WHO Classification." Blood 114, n. 22 (20 novembre 2009): 2776. http://dx.doi.org/10.1182/blood.v114.22.2776.2776.
Testo completoAbstract (sommario):
Abstract Abstract 2776 Poster Board II-752 Introduction: We wondered whether prognostic factors have similar relevance in different subpopulations of MDS patients. Methods: Our analysis was based on patients with primary, untreated MDS, including 181 RA, 169 RARS, 649 RCMD, 322 RSCMD, 79 5q-syndromes, 290 RAEB I, 324 RAEB II, 266 CMML I, 64 CMML II, and 209 RAEB-T. The impact of prognostic variables in univariate analysis was compared in subpopulations of patients defined by medullary blast count, namely <5%, ≥5% (table), ≥10%, and ≥20% (not shown), as well as 3 subpopulations defined by the cytogenetic risk groups according to IPSS (table). Multivariate analysis of prognostic factors was performed for cytogenetically defined subgroups and WHO-subtypes. Results: Strong prognostic factors in all blast-defined subgroups were hemoglobin, transfusion dependency, increased WBC, age, and LDH. However, all variables became less important in patients with ≥20% blasts (RAEB-T) and increased WBC was rare. Platelet count and cytogenetic risk groups were relevant in patients with <5%, ≥5%, and ≥10% marrow blasts, but not in RAEB-T. Marrow fibrosis was important in patients with <5% or ≥5% blasts, but not ≥10%. Gender and ANC <1000/μl were significant only in patients with a normal blast count. Furthermore, we looked for the effect of the karyotypes, relevant for IPSS scoring (-Y, del5q, del20q, others, del7q/-7, complex), and found a comparable influence on survival, irrespective whether patients had < or ≥5% marrow blasts. In subpopulations defined by cytogenetic risk groups, several prognostic factors were highly significant in univariate analysis, if patients had a good risk karyotype. These included hemoglobin, sex, age, LDH, increased WBC, transfusion need, and blast count (cut-offs 5%, 10%, and 20%). In the intermediate risk group only LDH, platelets, WBC, and blasts were significant prognostic factors, while in the high risk group only platelets and blast count remained significant. Multivariate analysis was performed for the cytogenetic risk groups and for subgroups defined by WHO subtypes. The analysis considered blast count (</≥5%), hemoglobin, platelets, ANC, cytogenetic risk group, transfusion need, sex, and age. In the subgroup including RA, RARS, and 5q-syndrome, LDH, transfusion, and age in descending order were independent prognostic parameters. In the RCMD+RSCMD group, karyotype, age, transfusion, and platelets were relevant factors. In the RAEB I+II subgroup, the order was hemoglobin, karyotype, age, and platelets, while in CMML I+II only hemoglobin had independent influence. In RAEB-T none of the factors examined was of independent significance. Looking at cytogenetic risk groups, in the favorable group, several variables independently influenced survival, namely transfusion, blasts, age, sex, and LDH (in this order). Interestingly, in the intermediate and high risk group, only blast count and platelets retained a significant impact. Conclusion: Univariate analysis showed prognostic factors (except ANC) included in IPSS and WPSS are relevant in most subgroups defined by marrow blast percentage. However, they all lose their impact if the blast count exceeds 20%. Regarding cytogenetic risk groups, several prognostic factors lose their influence already in the intermediate risk group. This underscores the prognostic importance of MDS cytogenetics. Multivariate analysis showed MDS subpopulations defined by WHO types also differ with regard to prognostic factors. In particular, CMML and RAEB-T stand out against the other MDS types. Disclosures: Kuendgen: Celgene: Honoraria. Hildebrandt:Celgene: Research Funding. Gattermann:Novartis: Honoraria, Participation in Advisory Boards on deferasirox clinical trials. Germing:Novartis, Celgene: Honoraria, Research Funding.
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Rosas, Juan E., Maia Escobar, Sebastián Martínez, Pedro Blanco, Fernando Pérez, Gastón Quero, Lucía Gutiérrez e Victoria Bonnecarrère. "Epistasis and Quantitative Resistance to Pyricularia oryzae Revealed by GWAS in Advanced Rice Breeding Populations". Agriculture 10, n. 12 (11 dicembre 2020): 622. http://dx.doi.org/10.3390/agriculture10120622.
Testo completoAbstract (sommario):
Rice blast caused by Pyricularia oryzae is a major rice disease worldwide. Despite the detailed knowledge on major resistance genes available to date, little is known about how these genes interact with quantitative blast resistance loci and with the genetic background. Knowledge on these interactions is crucial for assessing the usefulness of introgressed resistance loci in breeding germplasm. Our goal was to identify quantitative trait loci (QTL) for blast resistance in rice breeding populations and to describe how they interact among each other and with the genetic background. To that end, resistance to blast was mapped by genome-wide association study (GWAS) in two advanced rice breeding subpopulations, one made of 305 indica type inbred lines, and the other of 245 tropical japonica inbred lines. The interactions and main effects of blast resistance loci were assessed in a multilocus model. Well known, major effect blast resistance gene clusters were detected in both tropical japonica (Pii/Pi3/Pi5) and indica (Piz/Pi2/Pi9) subpopulations with the GWAS scan 1. When these major effect loci were included as fixed cofactors in subsequent GWAS scans 2 and 3, additional QTL and more complex genetic architectures were revealed. The multilocus model for the tropical japonica subpopulation showed that Pii/Pi3/Pi5 had significant interaction with two QTL in chromosome 1 and one QTL in chromosome 8, together explaining 64% of the phenotypic variance. In the indica subpopulation a significant interaction among the QTL in chromosomes 6 and 4 and the genetic background, together with Piz/Pi2/Pi9 and QTL in chromosomes 1, 4 and 7, explained 35% of the phenotypic variance. Our results suggest that epistatic interactions can play a major role modulating the response mediated by major effect blast resistance loci such as Pii/Pi3/Pi5. Furthermore, the additive and epistatic effects of multiple QTL bring additional layers of quantitative resistance with a magnitude comparable to that of major effect loci. These findings highlight the need of genetic background-specific validation of markers for molecular assisted blast resistance breeding and provide insights for developing quantitative resistance to blast disease in rice.
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Yalciner, Hakan. "Structural Response to Blast Loading: The Effects of Corrosion on Reinforced Concrete Structures". Shock and Vibration 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/529892.
Testo completoAbstract (sommario):
Structural blast design has become a necessary part of the design with increasing terrorist attacks. Terrorist attacks are not the one to make the structures important against blast loading where other explosions such as high gas explosions also take an important place in structural safety. The main objective of this study was to verify the structural performance levels under the impact of different blast loading scenarios. The blast loads were represented by using triangular pulse for single degree of freedom system. The effect of blast load on both corroded and uncorroded reinforced concrete buildings was examined for different explosion distances. Modified plastic hinge properties were used to ensure the effects of corrosion. The results indicated that explosion distance and concrete strength were key parameters to define the performance of the structures against blast loading.