Effects of high-dose glucose-insulin-potassium on acute coronary syndrome patients receiving reperfusion therapy:a meta-analysis

BACKGROUND:This meta-analysis aimed to assess the efficacy of high-dose glucose-insulinpotassium(GIK) therapy on clinical outcomes in acute coronary syndrome(ACS) patients receiving reperfusion therapy.METHODS:We searched the PubMed,Web of Science,MEDLINE,Embase,and Cochrane Library databases from inception to April 26,2022,for randomized controlled trials(RCTs) that compared high-dose GIK and placebos in ACS patients receiving reperfusion therapy.The primary endpoint was major adverse cardiovascular events(MACEs).RESULTS:Eleven RCTs with 884 patients were ultimately included.Compared with placebos,high-dose GIK markedly reduced MACEs(risk ratio [RR] 0.57,95% confidence interval [95% CI]:0.35 to 0.94,P=0.03) and the risk of heart failure(RR 0.48,95% CI:0.25 to 0.95,P=0.04) and improved the left ventricular ejection fraction(LVEF)(mean difference [MD] 2.12,95% CI:0.40 to 3.92,P=0.02) at 6 months.However,no difference was observed in all-cause mortality at 30 d or 1 year.Additionally,high-dose GIK was significantly associated with increased incidences of phlebitis(RR 4.78,95% CI:1.36 to 16.76,P=0.01),hyperglycemia(RR 9.06,95% CI:1.74 to 47.29,P=0.009) and hypoglycemia(RR 6.50,95% CI:1.28 to 33.01,P=0.02) but not reinfarction,hyperkalemia or secondary reperfusion.In terms of oxidative stress-lowering function,high-dose GIK markedly reduced superoxide dismutase(SOD) activity but not glutathione peroxidase(GSH-Px) or catalase(CAT) activity.CONCLUSION:Patients with ACS receiving reperfusion therapy exhibited a reduction in MACEs and good oxidative stress-lowering eflcacy in response to high-dose GIK.Moreover,with a higher incidence of complications such as phlebitis,hyperglycemia,and hypoglycemia.Furthermore,there were no observed survival benefits associated with high-dose GIK.More trials with long-term follow-up are still needed.

Septic shock due to cytomegalovirus colitis associated with rituximab use:A case report

BACKGROUND Cytomegalovirus(CMV)infections can cause significant morbidity and mortality in immunocompromised individuals.CMV targets dysfunctional lymphocytes.Chronic rituximab(RTX)therapy can cause B-lymphocyte dysfunction,increasing CMV risk.Rarely,CMV infections present with critical illness such as septic shock.CASE SUMMARY A 64-year-old African American woman presented with generalized weakness and non-bloody watery diarrhea of 4-6 weeks duration.She did not have nausea,vomiting or,abdominal pain.She had been on monthly RTX infusions for neuromyelitis optica.She was admitted for septic shock due to pancolitis.Blood investigations suggested pancytopenia and serology detected significantly elevated CMV DNA.Valganciclovir treatment led to disease resolution.CONCLUSION This case illustrates an extremely rare case of CMV colitis associated with RTX use presenting with septic shock.High suspicion for rare opportunistic infections is imperative in individuals with long-term RTX use.

Prognostic impact of hypernatremia for septic shock patients in the intensive care unit

BACKGROUND Hypernatremia represents a significant electrolyte imbalance associated with numerous adverse outcomes,particularly in cases of intensive care unit(ICU)-acquired hypernatremia(IAH).Nevertheless,its relevance in patients with septic shock remains uncertain.AIM To identify independent risk factors and their predictive efficacy for IAH to improve outcomes in patients with septic shock.METHODS In the present retrospective single-center study,a cohort of 157 septic shock patients with concurrent hypernatremia in the ICU at The First Affiliated Hospital of Soochow University,between August 1,2018,and May 31,2023,were analyzed.Patients were categorized based on the timing of hypernatremia occurrence into the IAH group(n=62),the non-IAH group(n=41),and the normonatremia group(n=54).RESULTS In the present study,there was a significant association between the high serum sodium concentrations,excessive persistent inflammation,immunosuppression and catabolism syndrome and chronic critical illness,while rapid recovery had an apparent association with normonatremia.Moreover,multivariable analyses revealed the following independent risk factors for IAH:Total urinary output over the preceding three days[odds ratio(OR)=1.09;95%CI:1.02–1.17;P=0.014],enteral nutrition(EN)sodium content of 500 mg(OR=2.93;95%CI:1.13–7.60;P=0.027),and EN sodium content of 670 mg(OR=6.19;95%CI:1.75–21.98;P=0.005)were positively correlated with the development of IAH.Notably,the area under the curve for total urinary output over the preceding three days was 0.800(95%CI:0.678–0.922,P=0.001).Furthermore,maximum serum sodium levels,the duration of hypernatremia,and varying sodium correction rates were significantly associated with 28-day in-hospital mortality in septic shock patients(P<0.05).CONCLUSION The present findings illustrate that elevated serum sodium level was significantly associated with a poor prognosis in septic shock patients in the ICU.It is highly recommended that hypernatremia be considered a potentially important prognostic indicator for the outcome of septic shock.

High-dose vs low-dose proton pump inhibitors for upper gastrointestinal bleeding:A meta-analysis

AIM:To evaluate the efficacy of high-dose proton pump inhibitors(PPIs)vs low-dose PPIs for patients with upper gastrointestinal bleeding.METHODS:PubMed,Embase,the Cochrane Library,and Web of Science were searched to identify relevant randomized controlled trials(RCTs).Eligible trials were RCTs that compared high-dose PPI with low-dose PPI following endoscopic hemostasis.The primary endpoint was rebleeding;secondary endpoints were patient numbers that needed surgery,and mortality.The meta-analysis was performed with a fixed effects model or random effects model.RESULTS:Nine eligible RCTs including 1342 patients were retrieved.The results showed that high-dose intravenous PPI was not superior to low-dose intra-venous PPI in reducing rebleeding[odds ratio(OR)= 1.091,95%confidential interval(CI):0.777-1.532],need for surgery(OR=1.522,95%CI:0.643-3.605) and mortality(OR=1.022,95%CI:0.476-2.196).Subgroup analysis according to different region revealed no difference in rebleeding rate between Asian patients(OR=0.831,95%CI,0.467-1.480)and European patients(OR=1.263,95%CI:0.827-1.929).CONCLUSION:Low-dose intravenous PPI can achieve the same efficacy as high-dose PPI following endoscopic hemostasis.

Predictors of post-treatment stenosis in cervical esophageal cancer undergoing high-dose radiotherapy

AIM To evaluate toxicity and treatment outcome of highdose radiotherapy(RT) for cervical esophageal cancer(CEC).METHODS We reviewed a total of 62 consecutive patients who received definitive RT for stage Ⅰ to Ⅲ cervical esophageal cancer between 2001 and 2015. Patients who received < 45 Gy, treated for lesions below sternal notch, treated with palliative aim, treated with subsequent surgical resection, or diagnosed with synchronous hypopharyngeal cancer were excluded. Treatment failures were divided into local(occurring within the RT field), outfield-esophageal, and regional [occurring in regional lymph node(s)] failures. Factors predictive of esophageal stenosis requiring endoscopic dilation were analyzed.RESULTS Grade 1, 2, and 3 esophagitis occurred in 19(30.6%), 39(62.9%), and 4 patients(6.5%), respectively, without grade ≥ 4 toxicities. Sixteen patients(25.8%) developed post-RT stenosis, of which 7 cases(43.8%) were malignant. Four patients(6.5%) developed tracheoesophageal fistula(TEF), of which 3(75%) cases were malignant. Factors significantly correlated with post-RT stenosis were stage T3/4(P = 0.001), complete circumference involvement(P < 0.0001), stenosis at diagnosis(P = 0.024), and endoscopic complete response(P = 0.017) in univariate analysis, while complete circumference involvement was significant in multivariate analysis(P = 0.003). A higher dose(≥ 60 Gy) was not associated with occurrence of postRT stenosis or TEF. With a median follow-up of 24.3(range, 3.4-152) mo, the 2 y local control, outfield esophageal control, progression-free survival, and overall survival(OS) rates were 78.9%, 90.2%, 49.6%, and 57.3%, respectively. Factors significantly correlated with OS were complete circumference involvement(P = 0.023), stenosis at diagnosis(P < 0.0001), and occurrence of post-RT stenosis or TEF(P < 0.001) in univariate analysis, while stenosis at diagnosis(P = 0.004) and occurrence of post-RT stenosis or TEF(P = 0.023) were significant in multivariate analysis. CONCLUSION Chemoradiation for CEC was well tolerated, and a higher dose was not associated with stenosis. Patients with complete circumferential involvement require close follow-up.

High-dose interferon-α2b induction therapy in combination with ribavirin for treatment of chronic hepatitis C in patients with non-response or relapse after interferon-a monotherapy

AIM： To evaluate the daily high-dose induction therapy with interferon-α2b （IFN-α2b） in combination with ribavirin for the treatment of patients who failed with interferon monotherapy and had a relapse, based on the assumption that the viral burden would decline faster, thus increasing the likelihood of higher response rates in this difficult-totreat patient group. METHODS： Seventy patients were enrolled in this study. Treatment was started with 10 NU IFN-α2b daily for 3 wk, followed by IFN-α2b 5 NU/TIW in combination with ribavirin （1 000-1 200 mg/d） for 21 wk. In case of a negative HCV RNA PCR, treatment was continued until wk 48 （IFN-α2b 3MU/TIW＋1000-1200 mg ribavirin/daily）. RESULTS： The dose of IFN-α2b or ribavirin was reduced in 16% of patients because of hematologic side effects, and treatment was discontinued in 7% of patients. An early viral response （EVR） was achieved in 60% of patients. Fifty percent of all patients achieved an end-oftreatment response （EOT） and d0% obtained a sustained viral response （SVR）. Patients with no response had a significantly lower response rate than those with a former relapse （SVR 30% vs 53%; P=0.049）. Furthermore, lower response rates were observed in patients infected with genotype la/b than in patients with non-1-genotype （SVR 28% vs7d%; P=0.001）. As a significant predictive factor for a sustained response, a rapid initial decline of HCV RNA could be identified. No patient achieving a negative HCV-RNA PCR at wk 18 or later eventually eliminated the virus. CONCLUSION： Daily high-dose induction therapy with interferon-α2b is well tolerated and effective for the treatment of non-responders and relapsers, when interferon monotherapy fails. A fast decline of viral load during the first 12 wk is strongly associated with a sustained viral response.

Dose-individualization Efficiently Maintains Sufficient Exposure to Methotrexate without Additional Toxicity in High-dose Methotrexate Regimens for Pediatric Acute Lymphoblastic Leukemia

Objective:Methotrexate(MTX)can be safely administered to most patients but may cause severe toxicity in others.This study aimed to summarize the characteristics of high-dose methotrexate(HD-MTX)chemotherapy and to evaluate whether the modified dose-adjustment program was able to improve the maintenance of sufficient MTX exposure levels while minimizing toxicities.Methods:We evaluated 1172 cycles of high-dose MTX chemotherapy from 294 patients who were treated according to the CCCG-ALL-2015 protocol(clinical trial number:ChiCTR-IPR-14005706)and analyzed the data of actual MTX dosage,MTX concentration,toxicity,and prognosis.We compared data between the dose-adjustment Program 1(fixed 20%reduction in dose)and the dose-adjustment Program 2(dose-individualization based on reassessment of the creatine clearance rate and the MTX concentration-monitoring point at 16 h),which were applied if the MTX clearance was delayed in the previous cycle.Results:The patients who used Program 2 had higher actual MTX infusion doses and infusion rates and were able to better maintain the MTX concentration at 44 h at the established target value than those on Program 1(P<0.001).No significant differences in toxicities were found between these two programs except that abnormal serum potassium levels and prolonged myelosuppression in intermediate-risk/high-risk patients were more frequently observed in patients using Program 2(P<0.001).No significant correlations were observed between the MTX dose,dose-adjustment programs,or MTX concentrations and relapse-free survival.Conclusion:Adjusting the MTX dose using Program 2 is more efficient for maintaining sufficient MTX exposure without significantly increasing the toxicity.

Propagation Properties of Shock Waves in Polyurethane Foam based on Atomistic Simulations

Porous materials are widely used in the field of protection because of their excellent energy absorption characteristics.In this work,a series of polyurethane microscopic models are established and the effect of porosity on the shock waves is studied with classical molecular dynamics simulations.Firstly,shock Hugoniot relations for different porosities are obtained,which compare well with the experimental data.The pores collapse and form local stress wave,which results in the complex multi-wave structure of the shock wave.The microstructure analysis shows that the local stress increases and the local velocity decreases gradually during the process of pore collapse to complete compaction.Finally,it leads to stress relaxation and velocity homogenization.The shock stress peaks can be fitted with two exponential functions,and the amplitude of attenuation coefficient decreases with the increase of density.Besides,the pore collapse under shock or non-shock are discussed by the entropy increase rate of the system.The energy is dissipated mainly through the multiple interactions of the waves under shock.The energy is dissipated mainly by the friction between atoms under non-shock.

The Experience of Pain and Anxiety in Cervical Cancer Patients Undergoing Multiple Fraction High-Dose Rate Brachytherapy: A Prospective Observational Study

Purpose: To evaluate the anxiety and pain levels of cervical cancer patients undergoing intracavitary multifraction high-dose rate (HDR) brachytherapy, as part of a process to develop guidelines for quality patient-centered care. Methods: Cervical cancer patients (n = 31) undergoingmultiple fraction HDR brachytherapy treatment at the National Institute of Oncology in Rabat (Morocco) completed ratings of pain and anxiety intensity using 11-point verbal analog scales, at 6 key time points over 2 brachytherapy insertion procedures and 4 brachytherapy fractions. Women were evaluated for psychological status at baseline before starting the brachytherapy process using the Hospital Anxiety and Depression Scale (HADS). Scores were grouped as follows: 0 - 7 = normal, 8 - 10 = borderline, 11 - 21 = abnormal. Factors that could affect anxiety levels such as education level, relationship status, number of pregnancies and prior surgical history were documented. Results: Between July and August 2020, 31 women with a median age of 49.6 years were evaluated (range: 27 - 70). The HADS score identified depression in 5 patients (16.1%) and anxiety in 12 patients (38.7%). Throughout both treatment procedures, anticipatory anxiety was reported, with a maximum intensity in the operating room during spinal anesthesia (3.23 ± 1.7) and during applicator insertion (2.97 ± 2.4). Moderate-to-severe anxiety scores were reported in 25.8% and 22.6% of patients respectively. Level of education showed a significant correlation with anxiety scores (p = 0.027). Pain increased significantly during the procedure (p ± 1.4) and applicator removal (4.74 ± 1.5) turned out to be the most painful parts of the procedure. No correlation was found between pain and anxiety levels. Conclusion: Intracavitary multifraction high-dose rate brachytherapy is associated with mild to moderate levels of pain and anxiety, although a subset of patients reported more severe symptoms and may require additional medical and psychological support, with particular emphasis on bed-rest duration and applicator removal. The development of effective interventions (both pharmacological and non-pharmacological) is needed to improve women’s experiences of brachytherapy for locally advanced cervical cancer.

Very-high-dose olanzapine for treatment-resistant schizophrenia

Treatment-resistant schizophrenia has an extremely negative impact on mental health and social life. If clozapine, the gold standard treatment, fails, there are very few options left. The literature suggests that high-dose olanzapine (20 - 60 mg/day) is a possible alternative. We report two cases in which very high doses of olanzapine were administered, with significant clinical improvements above 60 mg/day. Clinical, metabolic and cardiac tolerance was good. This report highlights the usefulness of very-high-dose olanzapine in treatment-resistant schizophrenia. The main hypotheses concerning the psychopharmacological mechanisms of very-high-dose olanzapine are discussed.

Experimental investigation on weak shock wave mitigation characteristics of flexible polyurethane foam and polyurea

In recent years,explosion shock wave has been considered as a signature injury of the current military conflicts.Although strong shock wave is lethal to the human body,weak shock wave can cause many more lasting consequences.To investigate the protection ability and characteristics of flexible materials and structures under weak shock wave loading,the blast wave produced by TNT explosive is loaded on the polyurethane foam with the density of 200.0 kg/m3(F-200)and 400.0 kg/m3(F-400),polyurea with the density of 1100.0 kg/m^(3)(P-1100)and structures composed of the two materials,which are intended for individual protection.Experimental results indicate that the shock wave is attenuated to weak pressure disturbance after interacting with the flexible materials which are not damaged.The shock wave protective capability of single-layer materials is dependent on their thickness,density and microscopic characteristics.The overpressure,maximum pressure rise rate and impulse of transmitted wave decrease exponentially with increase in sample thickness.For the same thickness,F-400 provides better protective capability than F-200 while P-1100 shows the best protective capability among the three materials.In this study,as the materials are not destroyed,F-200 with a thickness more than10.0 mm,F-400 with a thickness more than 4.0 mm,and P-1100 with a thickness more than 1.0 mm can attenuate the overpressure amplitude more than 90.0%.Further,multi-layer flexible composites are designed.Different layer layouts of designed structures and layer thickness of the single-layer materials can affect the protective performance.Within the research range,the structure in which polyurea is placed on the impact side shows the optimal shock wave protective performance,and the thicknesses of polyurea and polyurethane foam are 1.0 mm and 4.0 mm respectively.The overpressure attenuation rate reached maximum value of 93.3%and impulse attenuation capacity of this structure are better than those of single-layer polyurea and polyurethane foam with higher areal density.

Comparison of High-Dose Dexamethasone and Prednisone for Initial Treatment of Adult Primary Immune Thrombocytopenia

Prednisone is the most common first-line treatment for adult primary immune thrombocytopenia (ITP). However, the best initial therapeutic approach is still a matter of debate. Prior studies have shown that high-dose dexamethasone (HD-DXM) produces a high sustained efficacy not achieved by conventional prednisone therapy. However, the definition of response widely differs between individual reports, and this heterogeneity makes comparison of the efficacy difficult. The aim of our study was to compare the therapeutic outcomes of a conventional dose of prednisone with HD-DXM for adult ITP patients as initial therapy. Thirty patients treated with prednisone and 22 patients treated HD-DXM were retrospectively analyzed. No significant differences between the HD-DXM and prednisone groups were observed for the rates of complete response (68% vs. 70%) and response (18% vs. 17%). However, 1 year probability of sustained response was significantly greater in the HD-DXM group than in the prednisone group (78% vs. 38%;P = 0.008). No adverse events necessitating discontinuation of treatment were observed in either group. Our retrospective analysis showed that initial treatment with HD-DXM produced longer response duration compared to a conventional dose of prednisone. Randomized clinical trials are warranted to establish the optimal initial steroid therapy for adult ITP.

A New Variant of Combined Pulmonary Fibrosis and Emphysema from Long-Term High-Dose of Glucocorticoid Therapy: A Case Report

Recent studies have described the combination of both pulmonary emphysema and idiopathic interstitial lung disease (ILDs) by means of high-resolution computed axial tomography (HRCT). Definition of this syndrome was first named by Cottin as combined pulmonary fibrosis and emphysema (CPFE). Functional and radiological findings have showed that these patients are suffering from severe breathlessness, but whose pulmonary functional tests revealed no signs of obstruction, normal static lung volumes, and depressed DLco, most with a history of smoking [1] [2]. The radiological and endoscopic studies especially show that these patients have both areas of upper-lobe predominant emphysema and lesions compatible with fibrosis in both lung bases [3]. No prior research has reported any cases of such condition in person with no prior history of smoking as well as long-term high-dose of glucocorticoid therapy. In this case report, we discuss the presentation, diagnosis, and management of a 53-year-old non-smoker with increasing shortness of breath with a long-term high-dose of glucocorticoid therapy discovered to have an abnormal variant or presentation of CPFE. The cause of disease was attributed to a certain history of smoking in most studies;other potential risk factors have yet to be properly analyzed. This clinical report features a special case about the problem and solution surrounding this issue.

Successful treatment of group A streptococcal toxic shock syndrome occurring in late pregnancy:a case report

Streptococcal toxic shock syndrome(STSS)is an acute,life-threatening illness caused by invasive group A Streptococcus(iGAS).The initial manifestations of STSS are atypical,and may progress to shock,multiple organ dysfunction syndrome(MODS),and disseminated intravascular coagulation(DIC)quickly.

Demonstrating grating-based phase-contrast imaging of laser-driven shock waves

Single-shot X-ray phase-contrast imaging is used to take high-resolution images of laser-driven strong shock waves.Employing a two-grating Talbot interferometer,we successfully acquire standard absorption,differential phase-contrast,and dark-field images of the shocked target.Good agreement is demonstrated between experimental data and the results of two-dimensional radiation hydrodynamics simulations of the laser-plasma interaction.The main sources of image noise are identified through a thorough assessment of the interferometer’s performance.The acquired images demonstrate that grating-based phase-contrast imaging is a powerful diagnostic tool for high-energy-density science.In addition,we make a novel attempt at using the dark-field image as a signal modality of Talbot interferometry to identify the microstructure of a foam target.

Strong shock propagation for the finite-source circular blast in a confined domain

The circular explosion wave produced by the abrupt discharge of gas from a high-temperature heat source serves as a crucial model for addressing explosion phenomena in compressible flow.The reflection of the primary shock and its propagation within a confined domain are studied both theoretically and numerically in this research.Under the assumption of strong shock,the scaling law governing propagation of the main shock is proposed.The dimensionless frequency of reflected shock propagation is associated with the confined distance.The numerical simulation for the circular explosion problem in a confined domain is performed for validation.Under the influence of confinement,the principal shock wave systematically undergoes reflection within the domain until it weakens,leading to the non-monotonic attenuation of kinetic energy in the explosion fireball and periodic oscillations of the fireball volume with a certain frequency.The simulation results indicate that the frequency of kinetic energy attenuation and the volume oscillation of the explosive fireball align consistently with the scaling law.

A rat model of multicompartmental traumatic injury and hemorrhagic shock induces bone marrow dysfunction and profound anemia

Background:Severe trauma is associated with systemic inflammation and organ dysfunction.Preclinical rodent trauma models are the mainstay of postinjury research but have been criticized for not fully replicating severe human trauma.The aim of this study was to create a rat model of multicompartmental injury which recreates profound traumatic injury.Methods:Male Sprague-Dawley rats were subjected to unilateral lung contusion and hemorrhagic shock(LCHS),multicompartmental polytrauma(PT)(unilateral lung contusion,hemorrhagic shock,cecectomy,bifemoral pseudofracture),or na?ve controls.Weight,plasma toll-l ike receptor 4(TLR4),hemoglobin,spleen to body weight ratio,bone marrow(BM)erythroid progenitor(CFU-GEMM,BFU-E,and CFU-E)growth,plasma granulocyte colony-stimulating factor(G-CSF)and right lung histologic injury were assessed on day 7,with significance defined as p values<0.05(*).Results:Polytrauma resulted in markedly more profound inhibition of weight gain compared to LCHS(p=0.0002)along with elevated plasma TLR4(p<0.0001),lower hemoglobin(p<0.0001),and enlarged spleen to body weight ratios(p=0.004).Both LCHS and PT demonstrated suppression of CFU-E and BFU-E growth compared to naive(p<0.03,p<0.01).Plasma G-CSF was elevated in PT compared to both na?ve and LCHS(p<0.0001,p=0.02).LCHS and PT demonstrated significant histologic right lung injury with poor alveolar wall integrity and interstitial edema.Conclusions:Multicompartmental injury as described here establishes a reproducible model of multicompartmental injury with worsened anemia,splenic tissue enlargement,weight loss,and increased inflammatory activity compared to a less severe model.This may serve as a more effective model to recreate profound traumatic injury to replicate the human inflammatory response postinjury.

Dynamic convergent shock compression initiated by return current in high-intensity laser-solid interactions

We investigate the dynamics of convergent shock compression in solid cylindrical targets irradiated by an ultrafast relativistic laser pulse.Our particle-in-cell simulations and coupled hydrodynamic simulations reveal that the compression process is initiated by both magnetic pressure and surface ablation associated with a strong transient surface return current with density of the order of 10^(17) A/m^(2) and lifetime of 100 fs.The results show that the dominant compression mechanism is governed by the plasma β,i.e.,the ratio of thermal pressure to magnetic pressure.For targets with small radius and low atomic number Z,the magnetic pressure is the dominant shock compression mechanism.According to a scaling law,as the target radius and Z increase,the surface ablation pressure becomes the main mechanism generating convergent shocks.Furthermore,an indirect experimental indication of shocked hydrogen compression is provided by optical shadowgraphy measurements of the evolution of the plasma expansion diameter.The results presented here provide a novel basis for the generation of extremely high pressures exceeding Gbar(100 TPa)to enable the investigation of high-pressure physics using femtosecond J-level laser pulses,offering an alternative to nanosecond kJ-laser pulse-driven and pulsed power Z-pinch compression methods.

Experimental and numerical study on protective effect of RC blast wall against air shock wave

Prototype experiments were carried out on the explosion-proof performance of the RC blast wall.The mass of TNT detonated in the experiments is 5 kg and 20 kg respectively.The shock wave overpressure was tested in different regions.The above experiments were numerically simulated,and the simulated shock wave overpressure waveforms were compared with that tested and given by CONWEP program.The results show that the numerically simulated waveform is slightly different from the test waveform,but similar to CONWEP waveform.Through dimensional analysis and numerical simulation under different working conditions,the equation for the attenuation rate of the diffraction overpressure behind the blast wall was obtained.According to the corresponding standards,the degree of casualties and the damage degree of the brick concrete building at a certain distance behind the wall can be determined when parameters are set.The above results can provide a reference for the design and construction of the reinforced concrete blast wall.

Effect of the interval between two shocks on ejecta formation from the grooved aluminum surface

This work focuses on the effect of the interval between two shocks on the ejecta formation from the grooved aluminum(Al_(1100))surface by using smoothed particle hydrodynamics numerical simulation.Two unsupported shocks are obtained by the plate-impact between sample and two flyers at interval,with a peak pressure of approximately 30 GPa for each shock.When the shock interval varies from 2.11 to 7.67 times the groove depth,the bubble velocity reduces to a constant,and the micro jetting factor R_(J) from spike to bubble exhibits a non-monotonic change that decreases initially and then increases.At a shock interval of 3.6 times the groove depth,micro jetting factor R_(J) from spike to bubble reaches its minimum value of approximately 0.6.While,the micro jetting factor R_(F) from spike to free surface decreases linearly at first,and stabilizes around 0.25 once the shock interval surpasses 4.18 times the groove depth.When the shock interval is less than 4.18 times the groove depth,the unloading wave generated by the breakout of the first shock wave is superimpose with the unloading part of the second shock wave to form a large tensile area.