Crash simulation and development of automotive bumper impact beam design for weight reduction

Increasing fuel economy has been a principal issue in the development of new cars. Decrease in weight of vehicle components is one of the important approaches to solving the problem. In order to obtain the goal, researches sought for ways to design lighter and stronger bumper impact beams relinquishing neither impact absorbing capacity of bumpers nor the safety of vehicles. In this paper, a possible weight reduction of impact beam is examined by substituting conventional type of steel with high-strength steel (boron steel having tensile strength 1.5 GPa) with regard to variables such as frontal, offset and corner impact crash capability of a bumper impact beam. In addition, the effects of variation in structural differences in bumper impact beams (open section, closed section, open section with 5 stays) were carefully considered. Arguably, this analysis presents a good guide for an optimum design and development of bumper impact beams

Crash simulation and development of automotive bumper impact beam design for weight reduction

Increasing fuel economy has been a principal issue in the development of new cars. Decrease in weight of vehicle components is one of the important approaches to solving the problem. In order to obtain the goal, researches sought for ways to design lighter and stronger bumper impact beams relinquishing neither impact absorbing capacity of bumpers nor the safety of vehicles. In this paper, a possible weight reduction of impact beam is examined by substituting conventional type of steel with high-strength steel (boron steel having tensile strength 1.5 GPa) with regard to variables such as frontal, offset and corner impact crash capability of a bumper impact beam. In addition, the effects of variation in structural differences in bumper impact beams (open section, closed section, open section with 5 stays) were carefully considered. Arguably, this analysis presents a good guide for an optimum design and development of bumper impact beams

Spontaneous HBsAg loss in Korean patients: relevance of viral genotypes, S gene mutations, and covalently closed circular DNA copy numbers

Background/AimsOccult HBV infection can persist following HBsAg loss and be transmitted, but the virological features are not well defined.MethodsHere we investigated 25 Korean patients who lost HBsAg during follow up, either spontaneously or subsequent to therapy.ResultsWhereas subtype adr (genotype C) was found in 96% of HBsAg positive patients, 75 % of patients who lost HBsAg spontaneously were seemed to be infected with the ayw subtype with sequence similar to genotype D. Mutations in the major hydrophilic region (MHR) of HBsAg were found in 7 patients who lost HBsAg spontaneously. The mutations include T123S, M125I/N, C139R, D144E, V177A, L192F, and W196L, some of which have not been reported before. Functional analysis via transfection experiments indicate that the C139R and D144E mutations drastically reduced HBsAg antigenicity, while the Y225del mutation found in one interferon-treated patient impaired HBsAg secretion.ConclusionsLack of detectable HBsAg in patient serum could be explained by low level of ccc DNA in liver tissue, low antigenicity of the surface protein, or its secretion defect

An Apparatus for Performing Microtensile Tests at Elevated Temperatures inside a Scanning Electron Microscope

In this paper, we introduce an apparatus to perform microtensile tests at elevated temperatures inside a scanning electron microscope. The apparatus has a stroke of 250 μm with a displacement resolution of 10 nm and a load resolution of 9.7 μN. Measurements at elevated temperatures are performed through use of two silicon-based micromachined heaters that support the sample. Each heater consists of a tungsten heating element that also serves as a temperature gauge. To demonstrate the testing capabilities, tensile tests were performed on submicron Cu films at various temperatures up to 430 °C. Stress–strain curves show a significant decrease in yield strength and initial slope for the samples tested at elevated temperature, which we attribute to diffusion-facilitated grain boundary sliding and dislocation climb.Engineering and Applied Science

Hepatogastric fistula caused by direct invasion of hepatocellular carcinoma after transarterial chemoembolization and radiotherapy

A 63-year-old man with a history of hepatitis-B-related hepatocellular carcinoma (HCC) in the left lateral portion of the liver received repeated transcatheter arterial chemoembolization (TACE) and salvage radiotherapy. Two months after completing radiotherapy, he presented with dysphagia, epigastric pain, and a protruding abdominal mass. Computed tomography showed that the bulging mass was directly invading the adjacent stomach. Endoscopy revealed a fistula from the HCC invading the stomach. Although the size of the mass had decreased with the drainage through the fistula, and his symptoms had gradually improved, he died of cancer-related bleeding and hepatic failure. This represents a case in which an HCC invaded the stomach and caused a hepatogastric fistula after repeated TACE and salvage radiotherapy

Prospective Validation of FibroTest in Comparison with Liver Stiffness for Predicting Liver Fibrosis in Asian Subjects with Chronic Hepatitis B

Liver stiffness measurement (LSM) and FibroTest (FT) are frequently used as non-invasive alternatives for fibrosis staging to liver biopsy. However, to date, diagnostic performances of Enhanced Liver Fibrosis (ELF) test, which consists of hyaluronic acid, aminoterminal propeptide of procollagen type-III, and tissue inhibitor of matrix metalloproteinases-1, have not been compared to those of LSM and FT in Asian chronic hepatitis B (CHB) patients.Between June 2010 and November 2011, we prospectively enrolled 170 CHB patients who underwent liver biopsies along with LSM, FT, and ELF. The Batts system was used to assess fibrosis stages.Areas under receiver operating characteristic curves (AUROCs) to predict significant fibrosis (F≥2), advanced fibrosis (F≥3), and cirrhosis (F = 4) were 0.901, 0.860, and 0.862 for ELF, respectively; 0.937, 0.956, and 0.963 for LSM; and 0.896, 0.921, and 0.881 for FT. AUROCs to predict F≥2 were similar between each other, whereas LSM and FT had better AUROCs than ELF for predicting F≥3 (both p<0.05), and LSM predicted F4 more accurately than ELF (p<0.05). Optimized cutoffs of ELF to maximize sum of sensitivity and specificity were 8.5, 9.4, and 10.1 for F≥2, F≥3, and F = 4, respectively. Using suggested ELF, LSM and FT cutoffs to diagnose F1, F2, F3, and F4, 91 (53.5%), 117 (68.8%), and 110 (64.7%) patients, respectively, were correctly classified according to histological results.ELF demonstrated considerable diagnostic value in fibrosis staging in Asian CHB patients, especially in predicting F≥2. However, LSM consistently provided better performance for predicting F≥3 and F4

Performance evaluation of the HepB Typer-Entecavir kit for detection of entecavir resistance mutations in chronic hepatitis B

Background/AimsMolecular diagnostic methods have enabled the rapid diagnosis of drug-resistant mutations in hepatitis B virus (HBV) and have reduced both unnecessary therapeutic interventions and medical costs. In this study we evaluated the analytical and clinical performances of the HepB Typer-Entecavir kit (GeneMatrix, Korea) in detecting entecavir-resistance-associated mutations.MethodsThe HepB Typer-Entecavir kit was evaluated for its limit of detection, interference, cross-reactivity, and precision using HBV reference standards made by diluting high-titer viral stocks in HBV-negative human serum. The performance of the HepB Typer-Entecavir kit for detecting mutations related to entecavir resistance was compared with direct sequencing for 396 clinical samples from 108 patients.ResultsUsing the reference standards, the detection limit of the HepB Typer-Entecavir kit was found to be as low as 500 copies/mL. No cross-reactivity was observed, and elevated levels of various interfering substances did not adversely affect its analytical performance. The precision test conducted by repetitive analysis of 2,400 replicates with reference standards at various concentrations showed 99.9% agreement (2398/2400). The overall concordance rate between the HepB Typer-Entecavir kit and direct sequencing assays in 396 clinical samples was 99.5%.ConclusionsThe HepB Typer-Entecavir kit showed high reliability and precision, and comparable sensitivity and specificity for detecting mutant virus populations in reference and clinical samples in comparison with direct sequencing. Therefore, this assay would be clinically useful in the diagnosis of entecavir-resistance-associated mutations in chronic hepatitis B

Tenofovir disoproxil fumarate monotherapy for nucleos(t)ide-naïve chronic hepatitis B patients in Korea: data from the clinical practice setting in a single-center cohort

Background/AimsThis study assessed the antiviral efficacy and safety of tenofovir disoproxil fumarate (TDF) for up to 12 months in Korean treatment-naïve chronic hepatitis B (CHB) patients.MethodsA total of 411 treatment-naïve CHB patients who had been treated with TDF for at least 3 months (median 5.6) were consecutively enrolled. Clinical, biochemical, virological parameters and treatment adherence were routinely assessed every 3 months.ResultsThe median age was 51.3 years, 63.0% of the patients were male, 49.6% were HBeAg (+), and 210 patients had liver cirrhosis. The median baseline HBV DNA was 5.98 (SD 1.68) log10 IU/mL. Among the patients completing week 48, 83.3% had a complete virologic response (CVR, <12 IU/mL by HBV PCR assay), and 88.2% had normalized levels of alanine aminotransferase (ALT). The cumulative probabilities of CVR at 3, 6, 9 and 12 months were 22.8%, 53.1%, 69.3% and 85.0%. During the follow-up period, 9.8% patients achieved HBeAg loss and 7.8% patients achieved HBeAg seroconversion. There was no virological breakthrough after initiating TDF. The most common TDF-related adverse event was gastrointestinal upset, and three patients discontinued TDF therapy. However, no serious life-threatening side effect was noted.ConclusionsIn a clinical practice setting, TDF was safe and highly effective when administered for 12 months to Korean treatment-naïve CHB patients

Antiviral efficacies of currently available rescue therapies for multidrug-resistant chronic hepatitis B

Background/AimsThe incidence of multidrug-resistant (MDR) chronic hepatitis B (CHB) during sequential lamivudine (LAM) and adefovir dipivoxil (ADV) treatment is increasing. We investigated the antiviral efficacies of various rescue regimens in patients who failed sequential LAM-ADV treatment.MethodsForty-eight patients (83.3% of whom were HBeAg-positive) who failed sequential LAM-ADV treatment were treated with one of the following regimens: entecavir (ETV) (1 mg) monotherapy (n=16), LAM+ADV combination therapy (n=20), or ETV (1 mg)+ADV combination therapy (n=12). All patients had confirmed genotypic resistance to both LAM and ADV and were evaluated every 12 weeks.ResultsThe baseline characteristics and treatment duration did not differ significantly among the study groups. During the treatment period (median duration: 100 weeks), the decline of serum HBV DNA from baseline tended to be greatest in the ETV+ADV group at all-time points (week 48: -2.55 log10 IU/mL, week 96: -4.27 log10 IU/mL), but the difference was not statistically significant. The ETV+ADV group also tended to have higher virologic response rates at 96 weeks compared to the ETV monotherapy or LAM+ADV groups (40.0% vs. 20.0% or 20.0%, P=0.656), and less virologic breakthrough was observed compared to the ETV monotherapy or LAM+ADV groups (8.3% vs. 37.5% or 30.0%; P=0.219), but again, the differences were not statistically significant. HBeAg loss occurred in one patient in the ETV+ADV group, in two in the ETV monotherapy group, and in none of the LAM+ADV group. The safety profiles were similar in each arm.ConclusionsThere was a nonsignificant tendency toward better antiviral efficacy with ETV+ADV combination therapy compared to LAM+ADV combination therapy and ETV monotherapy for MDR CHB in Korea, where tenofovir is not yet available

Efficacy of switching from adefovir to tenofovir in chronic hepatitis B patients who exhibit suboptimal responses to adefovir-based combination rescue therapy due to resistance to nucleoside analogues (SATIS study)

Background/Aims It remains to be determined whether switching from adefovir (ADV) to tenofovir (TDF) provides better virological outcomes in patients exhibiting suboptimal responses to ADV plus nucleoside analogue (ADV+NA) therapy for NA-resistant chronic hepatitis B (CHB). Methods In this prospective trial, patients who showed partial responses (defined as serum hepatitis B virus [HBV] DNA >60 IU/mL) to ADV+NA therapy for NA resistance were randomly allocated to receive TDF plus NA (TDF+NA group, n=16) or to continue their current therapy (ADV+NA group, n=16). The primary end point was the proportion of patients with complete virological response (CVR, defined as serum HBV DNA 2log10 IU/mL was more likely in the TDF+NA group at both 24 and 48 weeks (68.8% vs. 56.3%, P=0.014 vs. 81.3% vs. 56.3%, P=0.001, respectively). During the follow-up, the rate of HBeAg seroconversion was higher in the TDF+NA group than the ADV+NA group (12.5% vs. 6.25%, P=0.640), as was that for the hepatitis B surface antigen (6.25% vs. 0%, P=0.080). No serious adverse events due to antiviral agents occurred. Conclusion In patients exhibiting suboptimal responses to ADV+NA therapy for NA-resistant CHB, switching from ADV to TDF might provide better virological outcomes