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We investigated various numerical methods including a physical-based empirical equation, linear regression, shallow neural network, and deep learning approaches, to compare their accuracy for predicting the hardness of tempered martensite in low alloy steels. The physical-based empirical equation, which had been previously proposed with experimental data, was labelled and used in the present study. While it had a smaller number of coefficients, the prediction accuracy of the physical-based empirical equation was almost similar to that of the regression model based on the response surface method. The prediction accuracy of the machine learning models clearly improved as the number of layers increased and became more complicated in structure before the model began to overfit. The key point we found was that a single layered neural network model with optimized hyperparameters resulted in similar or better hardness prediction performance compared to deep learning models with a more complex architecture. We also analyzed 18 research papers from the literature which used neural network models to predict the hardness of steels. Only two recent papers adopted a convolutional neural network, as a kind of deep learning model, in a new attempt to predict hardness. The other 16 papers from 1998 to 2021 commonly chose shallow neural network models because a more complicated model is less effective than a simple model for regression problems with well-labeled experimental data in materials science and engineering.

Ni-based amorphous alloys are a unique class of materials that are attracting attention in biomass plants because of their outstanding physical properties at high temperatures. Several studies have investigated and designed the relationships between the input and target properties of alloys using machine learning algorithms. The extensive use of these models has a limitation in that the required composition is yet to be determined. To address this issue, we trained four machine learning algorithms to design Ni-based amorphous alloys and predict their thermal properties. The machine learning algorithms were trained using only the compositions of Ni-based amorphous alloys obtained from the relevant literature as the input feature data. Random forest regression was selected to predict and design the Ni-based amorphous alloys. We applied this algorithm to design amorphous alloys with the desired thermal properties and an optimal composition determined via particle swarm optimization. A melt spinner was used to fabricate the alloy. X-ray diffraction and differential thermal analyses were used to evaluate the specimens. Empirical equations were proposed for use in industrial fields.

IntroductionThe easiest way to prevent noise-induced hearing loss (NIHL) is to wear earplugs. The Republic of Korea (ROK) Ministry of National Defense (MND) is supplying earplugs to prevent NIHL, but many patients still suffer from this. We speculated that earplugs would have a high NIHL rate, depending on the rate of use of earplugs, regardless of the rate of supply. Therefore, we conducted this study to investigate the relationship between the use of earplugs and hearing loss by ROK military personnel.MethodsThe study used data from the Military Health Survey conducted in 2014–2015, which included 13 470 questionnaires completed by ROK military personnel. Hearing loss and earplug use were self-reported. Logistic regression analysis was used to assess associations between earplug use and hearing loss.ResultsThe study sample included 13 470 ROK military personnel (response rate of 71.2%) (Army, 8330 (61.8%); Navy/Marines, 2236 (16.6%); and Air Force, 2904 (21.6%)). Overall, 18.8% of Korean military personnel reported that they always wore earplugs, and 2.8% reported hearing loss. In logistic regression analysis, there were significant differences in the rates of hearing loss associated with wearing earplugs sometimes (OR=1.48, 95% CI 1.07 to 2.05) and never wearing earplugs (OR=1.53, 95% CI 1.12 to 2.10). In subgroup analysis, in Air Force, non-combat branch, forward area and long-term military service personnel increased hearing loss was associated with not wearing earplugs.ConclusionOur study confirmed that within the ROK military, there is an association between hearing loss and lack of earplug use. In the ROK MND, Army, Navy/Marines and Air Force headquarters must provide guidelines for the use of earplugs during field training to protect military personnel’s hearings and, if necessary, need to be regulated or institutionalised.

In this study, we investigated the effects of precipitates and oxide dispersoids on the high-temperature mechanical properties of oxide dispersion-strengthened (ODS) Ni-based super alloys. Two ODS Ni-based super alloy rods with different chemical compositions were fabricated by high-energy milling and hot extrusion process at 1150℃ to investigate the effects of precipitates on high-temperature mechanical properties. Further, the MA6000N alloy is an improvement over the commercial MA6000 alloy, and the KS6000 alloy has the same chemical composition as the MA6000 alloy. The phase and microstructure of Ni-based super alloys were investigated by X-ray diffraction and scanning electron microscopy. It was found that MC carbide precipitates and oxide dispersoids in the ODS Ni-based super alloys developed in this study may effectively improve high-temperature hardness and creep resistance.

BackgroundThe prevalence of depression is relatively high in the Korean military. Social support is a protective factor against depression and is classified into four categories: emotional support—having the sense of feeling loved; instrumental support—receiving material assistance; informational support—receiving advice; appraisal support—feeling valued and respected for one's abilities.ObjectiveTo investigate the effect of support from one’s superior on depression among Republic of Korea (ROK) military officers.Methods2047 participants from the 2015 Military Health Survey were included in the study. The Korean version of the Beck Depression Inventory was used to measure depression, and a self-reported questionnaire was used to assess support from one’s superior. A chi-squared test and multiple logistic regression were used to analyse the data.ResultsOf the 2047 participants, 177 (8.6%) had depression. Military officers who did not receive support from their superior were more likely to have depression than than those who did receive support (OR=2.09, 95% CI 1.30 to 3.36). Additionally, military personnel who did not receive emotional or appraisal support were more likely to have depression (emotional support: OR=2.37, 95% CI 1.31 to 4.29; appraisal support: OR=1.56, 95% CI 1.48 to 2.75).ConclusionsOur study found that depression in military officers was associated with lack of support from superiors. In particular, emotional support and appraisal support had a statistically significant effect. Therefore, we suggest that the ROK armed forces consider early intervention and management for high-risk groups. A social support programme and organisational atmosphere are also needed to improve supportive ability and skills of superiors.

IntroductionAccording to data released by the Korea National Statistical Office, the number of accidents has been decreasing since 2012. However, a considerable number of deaths related to safety accidents (23–46 deaths) are still reported annually. This study aimed to observe the correlation between accident prevention activities in the Republic of Korea (ROK) military and the incidence of safety accidents.MethodsThe study used data from the 2014–2015 Military Health Survey and included 13 618 responses (Army: 8414 (61.8%); Navy/Marine: 2262 (16.6%); Air Force: 2942 (21.6%)) from the ROK military personnel. Accident experiences and thoughts on accident prevention activities were self-reported. Multiple logistic regression analysis was used to examine the validity of accident prevention activity and accident experience.ResultsOf the 13 618 military personnel who responded, 12.0% reported experiencing safety accidents in the military and 1020 (7.5%) felt that accident prevention activities in the military were insufficient. On logistic regression analysis, we found a significant difference (insufficiency OR=1.56, CI 1.31 to 1.86). In particular, military personnel who belong to the Army and Navy were more likely to think that accident prevention activities were insufficient. In addition, military personnel who experienced falls/slips, crash, and laceration/puncture wound/amputation/penetrating wound accidents were more likely to think accident prevention activities were insufficient.ConclusionsOur study found that accident prevention activities in the military and accident experiences were related. It is necessary for the ROK Ministry of Defense, Army, Navy and Air Force headquarters to re-evaluate their accident prevention systems.

This study investigated the effect of the water and gas atomized Fe–Si powders on the densification behavior and consequential magnetic properties of the sintered soft magnetic alloys by metal injection molding. The water and gas atomized Fe–Si powders were used to fabricate the injection molded parts with the same solids loading of 58 vol% to analyze the inherent characteristics of each powder admixture. Dilatometry analysis was performed to understand the densification behavior of the water and gas atomized powders, and the master sintering curve model was developed to quantify the differences. The results showed that a significant amount of oxides in the water atomized powder reduced not only the densification but also the overall magnetic properties. The gas atomized sample exhibited the higher sintered density than the water atomized sample, and consequentially higher magnetic induction was obtained. The lower core loss, lower coercivity, and the higher permeability were also obtained from the gas atomized sample with the relatively low oxide level and large grain size. In addition, Fe-10.2 wt% P (Fe-17 at% P) powder was added to activate the liquid phase sintering, as a method to overcome the weakness of poor densification of the Fe–Si powders. Although both the water and gas atomized samples achieved near-full density with Fe-10.2 wt% P, the gas atomized sample yielded superior magnetic properties as compared with the water atomized sample.

With the growing prevalence of chronic diseases, the proportion of unmet needs is increasing. In this study, we investigated the effect of practicing health behaviors on unmet needs among patients with chronic diseases, using data from the Korea Health Panel Survey conducted between 2014–2017. Participants (n = 4069) aged 19 or older, with at least one chronic disease (hypertension, diabetes mellitus, dyslipidemia, or arthrosis) and with existing follow up data were selected. Health behaviors combined three variables: not presently smoking, not belonging to high-risk drinking group, and indulging in moderate- or high-intensity exercise. Those who met all three criteria were classified as the practicing health behaviors group. Generalized Estimating Equation analysis was performed to consider correlated data within a subject. Of the participants, 23.9% practiced health behaviors. Participants who did not practice health behaviors were significantly more likely to have unmet needs compared with those who did (OR: 1.24, 95% CI: 1.10–1.39). Further research would be needed to verify the impact of practicing health behavior on unmet needs.

Background: To examine the association between sitting time and non-alcoholic fatty liver disease among South Koreans aged ≥20 years. Methods : Data from the 2016–2018 Korea National Health and Nutrition Examination Survey were used for the analysis. Non-alcoholic fatty liver disease was diagnosed according to a hepatic steatosis index of >36. Sitting time was categorized into as < 5, 5 -7, 8 – 10, and > 10 hours. Multiple logistic regression analysis was used to examine the association between sitting time and non-alcoholic fatty liver disease in South Korean population. Results : A total of 13,518 participants were enrolled. The odds for having NAFLD in 5 – 7, 8 – 10, and > 10 sitting hours were 1.04 (CI: 0.85-1.28), 1.23(CI: 1.01-1.51), and 1.33(CI: 1.10-1.62), respectively. The odds ratio increased in magnitude with longer hours of sitting time (test for trend: P-value = 0.0009). Conclusion : Advising physical exercises and discouraging sedentary activities may help to alleviate NAFLD among the South Korean population.

In this study, we investigated the effect of crystalline structures on the magnetic properties of the Fe-based amorphous powder. We intentionally produced uniformly dispersed nanocrystallites inside the Fe-based amorphous powder using a combined process of mechanical milling and thermal annealing. In the case of powder produced after 30 min of ball milling followed by annealing at 400 °C, coercivity was decreased by 96.88% from 3698.73 to 115.49 A/m, and magnetization was increased 2.60% from 1.92 × 10−4 to 1.97 × 10−4 Wbm/kg. The simultaneous improvement of coercivity and magnetization can be attributed to the homogeneous generation of a small number of nanocrystallites as well as the release of residual stress.

This study investigated Fe-17 at% P addition effects on the magnetic properties of Fe-3.5 wt% Si alloys to enhance the electrical resistivity and core loss in powder injection molding. Considering the lowest melting point for 17 at% of P in the Fe-P phase diagram, the effect of P in Fe-3.5 wt% Si was analyzed by adding Fe-17 at% P from 0 to 12 wt% with 4 wt% increments. The feedstocks were prepared based on the processing optimization with respect to the critical solid loading, mixing homogeneity, and binder decomposition. The microstructure; relative density; electrical resistivity; and C, O, N, and S impurities of the sintered alloys were analyzed in correlation with the magnetic properties. The magnetic induction (B5000), maximum permeability, coercivity at 400 Hz and core loss in the frequency range from 50 to 1000 Hz at 1 T were analyzed. The higher magnetic induction and the lower eddy current loss with increasing Fe-17 at% P addition were induced by the higher relative density and electrical resistivity, respectively.

Soft magnetic powder injection molding is a net-shape production technology to fabricate sintered soft magnets. Powder injection molding technology for soft magnetic materials can be expected to develop a new type of electromagnetic components with the miniaturization and complexity design. In this work, 8 wt.% of iron-phosphorus powders (Fe-17 at.% P) were added to carbonyl iron powders to improve the magnetic performances with PIM process. Soft magnetic feedstocks were fabricated by optimized PIM process using a wax-based binder system. The critical solids loading of feedstocks were measured to determine the optimal solids loading, and injection molding process was conducted for the PIMed soft magnetic parts. The effect of Fe-17 at.% P addition to carbonyl iron powder was investigated on the sintering behaviors and magnetic properties. It was observed that sample with Fe-17 at.% P addition had optimum relative density (99.8%) and magnetic polarization (28,299 Gauss) at sintering temperature 1400°C in a hydrogen atmosphere.

Electromagnetic (EM) wave absorption properties are affected by the thickness and surface area of absorbing materials. In this study, a facile ball-milling process was introduced to effectively reduce the diameter and increase the aspect ratio of carbonyl iron powder (CIP), which is one of the most commercially available EM-absorbing materials. The size, aspect ratio, and consequent surface area of CIP were manipulated by controlling the milling parameters to investigate their effects on EM absorption properties. The results indicated that ball-milled CIPs exhibited better EM wave absorption ability when compared with that of pristine CIPs. However, significant differences in minimum reflection loss values were not observed between CIPs with different morphologies and similar specific surface areas. Hence, both fine and flaky CIPs were considered as beneficial for EM wave absorption.

In this study, the electromagnetic (EM) wave absorption ability of carbonyl iron powder (CIP)/graphite composites produced by ball milling were studied in a range of 28.5 GHz to examine the effects of the morphology and volume fraction of graphite on EM wave absorption ability. The results indicated that a ball milling technique was effective in exfoliating the graphite and covering it with CIP, thereby markedly increasing the specific surface area of the hybrid powder. The increase in the surface area and hybridization with dielectric loss materials (i.e., graphite) improved EM absorbing properties of CIP in the range of S and X bands. Specifically, the CIP/graphite composite containing 3 wt% graphite exhibited electromagnetic wave absorption of −13 dB at 7 GHz, −21 dB at 5.8 GHz, and −29 dB at 4.3 GHz after 1 h, 8 h, and 16 h of milling, respectively.

Sleep is exceedingly important for our physical, physiological, psychological, and social health. Currently, few Koreans get the recommended daily amount of sleep. Stress can also have a major impact on our physiological, neurological, and mental health. In this study, we explored the correlation between sleep duration and perceived stress. The study used data from the Community Health Survey (CHS), 2017, which included 133,444 responses from Koreans. Sleeping time and stress were measured by self-diagnosis. The relationship between sleeping time and stress was analyzed using the chi-square test and multivariable regression. Both men and women felt the most stress when they slept for an average of 6 h a day. The results of the subgroup analysis showed that even when they sleep for the same time, younger people felt more stressed than older people. In the group that slept for an average of 6 h a day, women were the most stressed. We observed a correlation between sleeping time and stress in Korean adults. We found that about 16.7% of Koreans were sleeping for less than 5 h. This is less than the 7&ndash, 9 h of sleep recommended by the National Sleep Foundation (NSF). In addition, stress was found to increase when sleep was insufficient. In particular, it was also observed that young people who slept for less than 8 h felt stressed more easily.

Additive manufacturing has many process variables and requires additive process optimization. Line energy and scan speed are the main process variables. The objective of this work aims to investigate the effect of changes in line energy and scan speed among the process variables on the mechanical and fatigue properties of the Ti6Al4V specimens fabricated by electron beam additive manufacturing method. The size of the pore inside the specimen was 40~60 μm with the exception of the condition of 0.2 kJ/m, and the specimen with poor fusion of more than 100 μm and gas pore was found to have lower room temperature tensile and fatigue properties compared to the optimal process conditions. As line energy increased, strain hardening occurred, and yield strength and tensile strength increased. The EL:0.3 kJ/m and 800 mm/s condition is a process condition that shows no defects such as unmelted powder and poor fusion, and it represents the best fatigue strength of 400 MPa. The fatigue strength of the specimen performed with hot isostatic pressing after additive manufacturing was measured at 550 MPa, an increase of 150 MPa, which resulted in high fatigue strength enhancement. The crack initiation site and propagation behavior were analyzed by observing the fatigue fracture section of the specimen according to the line energy.

Fe-based bulk metallic glasses (BMGs) are a unique class of materials that are attracting attention in a wide variety of applications owing to their physical properties. Several studies have investigated and designed the relationships between alloy composition and thermal properties of BMGs using an artificial neural network (ANN). The limitation of the wide-scale use of these models is that the required composition is yet to be found despite numerous case studies. To address this issue, we trained an ANN to design Fe-based BMGs that predict the thermal properties. Models were trained using only the composition of the alloy as input and were created from a database of more than 150 experimental data of Fe-based BMGs from relevant literature. We adopted these ANN models to design BMGs with thermal properties to satisfy the intended purpose using particle swarm optimization. A melt spinner was employed to fabricate the designed alloys. X-ray diffraction and differential thermal analysis tests were used to evaluate the specimens.

The mechanical behavior and microstructural evolution of aluminum metal matrix metallic composites fabricated under various process conditions were investigated to understand their process-structure–property relations. The novel techniques for arranging the matrix and reinforcement materials and controlling the processing atmosphere were applied to the extrusion process. The composites were comprised of matrix 1050 and reinforcement 6061 aluminum alloys with varying percent weight compositions and were arranged in a tailorable concentric annular pattern. The composites were shown to substantially increase compressive strength when the atmosphere of composite arrangement was evacuated prior to extrusion. Mechanical response of the composites were compared to the pre-extruded 1050 and 6061 aluminum alloys. The yield strengths of each composite, with varying percent weight compositions, were found to lie between those of matrix and reinforcement alloys, and abided by a simple rule-of-mixtures when considering weight composition. Highly elongated grains were oriented in the as-extruded composites along the extrusion direction and grains near the interface between two constituent alloys showed higher aspect ratio than in the interior region. The present study could lead to the optimum composite design for various industrial applications including all aluminum alloy overhead conductors with high strength and improved electric conductivity. Keywords: Aluminum alloys, Metal matrix metallic composites, Annular arrangement, Extrusion, Mechanical properties, Overhead conductor

Human papillomavirus (HPV) is a major cause of cervical neoplasia development. HPV screening is very important because early treatment can prevent cervical cancer. Omniplex-HPV is a polymerase chain reaction followed by Luminex xMAP bead microarray technology that is designed for detecting 40 HPV genotypes. The aim of this study is to evaluate the analytical and clinical performance of the Omniplex-HPV in comparison with that of the commercially available RFMP (restriction fragment mass polymorphism) HPV PapilloTyper. A total of 2,808 cervical swab specimens were obtained. Of these, only 1799 specimens had a cytology result. A type-specific direct sequencing test was performed using the reference method in case of discrepancies between the two test results. The overall percent agreement (OPA) between Omniplex-HPV and RFMP HPV PapilloTyper was 97.9% (κ=0.84; 95% CI: 0.81-0.88). The positive percent agreement (PPA) and the negative percent agreement (NPA) were 98.0% and 96.2%, respectively. The Omniplex-HPV and RFMP HPV PapilloTyper showed comparable sensitivities (90.2% and 91.9%, respectively) and specificities (91.3% each), while the Omniplex-HPV produced more accurate results and required less turnaround time and labor. The agreement between these two methods was excellent for HPV genotyping (P>0.05; McNemar’s test), and clinical sensitivity, specificity, and odds ratio of the two assays were comparable to the result of cytology tests in identifying high risk HPV. In conclusion, Omniplex-HPV and RFMP HPV PapilloTyper were highly comparable with regard to detection and genotyping analysis of HPV.

In this study, the effects of sintering temperature and the amount of Fe-17 at %P addition were studied for the Fe–Si–P sintered alloys. The Fe–Si–P sintered alloys were fabricated from the four powder admixtures containing Fe-3.5 wt% Si and Fe-17 at% P with powder injection molding. Better magnetic performances were obtained with Fe-17 at% P, which activated the liquid phase sintering and alloying of P and Si in the iron matrix. The higher density, lower oxides, and spheroidal grain were obtained with the increase of sintering temperature. Sintered density was the most important factor to the magnetic induction according to the comparative analysis of alloy composition and microstructural effects. For the permeability, coercivity, and core loss, on the other hand, they were much influenced by the alloy composition and microstructure, especially precipitation of secondary Fe3P phase, solid solution of P and Si in the iron matrix, population of the oxides.

MnBi magnets were prepared by melt-spinning, annealing, ball-milling, magnetic alignment, and subsequent hot compaction process. Mn-Bi melt-spun ribbons contained mainly unreacted Mn and Bi phases, including the low-temperature phase of MnBi. To increase the amount of this MnBi phase, these melt-spun ribbons were annealed under an oxygen-controlled atmosphere. As a result, a maximum saturation magnetization value of 57.90 emu/g was obtained when the melt-spun ribbons were annealed at 300 °C for 12 h. Bulk magnets fabricated by magnetic alignment and hot compaction processes showed a density of 8.71 g/cm 3 , a M r /M s ratio of 0.79, and a (BH) max value of 6.7 MGOe at room temperature. With the temperature increasing, the coercivity changed from 6387 Oe at room temperature to 18540 Oe at 150 °C and a (BH) max measured 5.5 MGOe at 150 °C.

We present variation of the magnetic properties of Fe77.8Nb0.2B14P6C2 amorphous alloys vitrified at different temperatures by changing the atomic structures dependent on the critical cooling rate. The thermophysical properties of the amorphous state achieved after quenching the melt with cold nitrogen atomization gas are compared with those obtained using hot nitrogen gas with a temperature corresponding to the supercooled liquid of the alloy above the glass transition (Tg) but below crystallization temperature (Tx). The differently vitrified Fe77.8Nb0.2B14P6C2 glasses represent different states of high pressure gas atomized amorphous powder at different temperatures obtained by adjusting the gas temperature during the atomization process. The magnetic properties of these different amorphous powders are also investigated. The saturation magnetic flux density of slowly cooled Glass2 is 1.38 T with 450 A/m coercivity corresponding to “semi-soft” magnetic materials. The fast cooled Glass1 powder shows typical soft magnetic properties with lower coercivity (174 A/m), even though the saturation magnetization flux densities are similar in both identical compositions of amorphous powder due to its entropy difference related to the formation of clusters. We can control the magnetic property of amorphous materials from soft to half-soft by adjusting freezing temperature and ordering of atoms.

Previous research suggests that adult men consume larger amounts of calories while eating-out than when eating meals prepared at home. Therefore, this study aimed to investigate the association between the daily eating-out rate and body mass index (BMI) in the Korean population. The study used data from 18,019 individuals aged &ge, 19 years who participated in the Korea National Health and Nutrition Examination Survey (KNHANES) from 2013 to 2016. BMI was measured according to the Asia-Pacific BMI measurement criteria. A multinomial logistic regression analysis was used to examine the validity of the association between the eating-out rate and BMI. In this population, women with higher eating-out rates were found to have higher BMIs. Specifically, the risks of becoming obese or overweight increased among those with a 1%&ndash, 50% (obesity odds ratio (OR) = 1.28, 95% confidence interval [CI]: 1.09&ndash, 1.51, overweight OR = 1.38, 95% CI: 1.14&ndash, 1.64) or 51%&ndash, 100% daily eating-out rate (obesity OR = 1.51, 95% CI: 1.24&ndash, 1.84, overweight OR = 1.50, 95% CI: 1.20&ndash, 1.87), relative to those who reported never eating-out. By contrast, no statistically significant association between the daily eating-out rate and BMI was observed among men. Notably, we observed positive associations of the daily eating-out rate with obesity and being overweight in South Korean women, but not men. Our findings suggest that education about proper habits when eating-out is needed to prevent obesity.

The purpose of this study was to investigate the association between intense physical activity and stress in Korean adolescents. The study used data from the Korea Youth Risk Behavior Web-Based Survey (KYRBWS), 2015&ndash, 2017, that included 170,359 responses from Korean adolescents. Intense activity and stress were measured by self-diagnosis. Additionally, the chi-square test and multiple logistic regression analyses were used. It was revealed that 78.9% of Korean adolescents were exposed to stress. Students who engaged in physical activity more than five times per week were less likely to be stressed than those who did not (boys odds ratio (OR): 0.79, confidence interval (CI): 0.78&ndash, 0.80, p for trend: &lt, 0.0001, girls OR: 0.77, CI: 0.75&ndash, 0.79, p for trend: &lt, 0.0001). The results indicated the same tendency among both boys and girls. The results of subgroup analysis revealed that students living with relatives or in childcare facilities were more likely to experience stress if they had insufficient exercise. In addition, the results confirmed that the probability of suicidal ideation increased as the frequency of exercise decreased. This study suggests that intense physical activity in Korean adolescents has a positive effect on stress management in both boys and girls. Hence, physical activity should be encouraged and implemented for managing stress.

We compared the sensitivities and specificities of peptide nucleic acid (PNA) probe-based real-time PCR (PNAqPCR™ TB/NTM) and Cobas TaqMan MTB assays for detection of Mycobacterium tuberculosis complex (MTBC) in clinical specimens. A total of 425 clinical specimens including 360 respiratory specimens and 65 non-respiratory specimens were evaluated for comparative analysis. In respiratory specimens, the sensitivity of TaqMan MTB and PNAqPCR assay for detection of MTBC was 82.9% and 91.5%, respectively. In non-respiratory specimens, the sensitivity of the TaqMan MTB and PNAqPCR assay was 23.1% and 76.9%, respectively. Overall, the sensitivity and specificity of the TaqMan MTB assay for detection of MTBC was 76.9% and 100%, respectively. The PNAqPCR assay had a sensitivity and specificity of 90% and 99.7%, respectively.

Ferromagnetic Mn-Al powders were produced by a gas-atomization method followed by heating treatment. The gas-atomized powders were E >-phase, which is a high temperature phase in the Mn-Al system. The E >-tau phase transformation took place by subsequent heat treatment at temperatures from 500 to 700 A degrees C. The gas-atomized powders with a smaller particle size formed the tau-phase faster and thus exhibited better magnetic properties. On the other hand, the annealing temperature and time similarly played important roles in determining the magnetic properties of the products. The Mn-Al powders of 25-38 mu m annealed at 550 A degrees C for 120 min exhibited a high coercivity of 3.2 kOe with a remanence of 38 emu/g.

Background A peptide nucleic acid (PNA) probe-based real-time PCR (PNAqPCR™ TB/NTM detection kit; PANAGENE, Korea) assay has been recently developed for the simultaneous detection of Mycobacterium tuberculosis complex (MTBC) and nontuberculous mycobacteria (NTM) in clinical specimens. The study was aimed at evaluation of the performance of PNA probe-based real-time PCR in respiratory specimens. Methods To evaluate potential cross-reactivity, the extracted DNA specimens from Mycobacterium species and non-mycobacterial species were tested using PNA probe-based real-time PCR assay. A total of 531 respiratory specimens (482 sputum specimens and 49 bronchoalveolar washing fluid specimens) were collected from 230 patients in July and August, 2011. All specimens were analyzed for the detection of mycobacteria by direct smear examination, mycobacterial culture, and PNA probe-based real-time PCR assay. Results In cross-reactivity tests, no false-positive or false-negative results were evident. When the culture method was used as the gold standard test for comparison, PNA probe-based real-time PCR assay for detection of MTBC had a sensitivity and specificity of 96.7% (58/60) and 99.6% (469/471), respectively. Assuming the combination of culture and clinical diagnosis as the standard, the sensitivity and specificity of the new real-time PCR assay for detection of MTBC were 90.6% (58/64) and 99.6% (465/467), respectively. The new real-time PCR for the detection of NTM had a sensitivity and specificity of 69.0% (29/42) and 100% (489/489), respectively. Conclusions The new real-time PCR assay may be useful for the detection of MTBC in respiratory specimens and for discrimination of NTM from MTBC.

A major problem of long-term antiviral therapy in chronic hepatitis B patients is the emergence of hepatitis B virus (HBV) mutations associated with drug resistance. Recently, a new array using peptide nucleic acids (PNAs), which are synthetic nucleic acid analogues, was developed for the detection of HBV mutations at six different codon positions associated with lamivudine (LAM) and adefovir (ADV) resistance. We compared the PNA array with direct sequencing and reverse hybridization (INNO-LiPA) in 73 samples obtained from chronic hepatitis B patients. The PNA array detected mutations associated with LAM and/or ADV resistance in 60 (82.2%) of the 73 samples. The overall concordance rate of PNA array and INNO-LiPA compared with direct sequencing was 99.5% and 98.2%, respectively. The rate of complete concordance between PNA array and INNO-LiPA was 92.7%. The PNA array assay results were comparable with INNO-LiPA for detection of HBV mutations associated with antiviral resistance.

Accurate and rapid diagnosis of Pandemic Influenza A/H1N1 2009 virus (H1N1 2009) infection is important for the prevention and control of influenza epidemics and the timely initiation of antiviral treatment. This study was conducted to evaluate the performance of several diagnostic tools for the detection of H1N1 2009. Flocked nasopharyngeal swabs were collected from 254 outpatients of suspected H1N1 2009 during October 2009. This study analyzed the performances of RealTime ready Inf A/H1N1 Detection Set (Roche), Influenza A (H1N1) Real-Time Detection Kit (Bionote), Seeplex Influenza A/B OneStep Typing set (Seeplex reverse transcriptase PCR [RT-PCR]), BinaxNow Influenza A & B test kit (Binax rapid antigen test [RAT]) and SD BIOLINE Influenza Ag kit (SD RAT). Roche and Bionote real-time RT-PCR showed identical results for the H1N1 2009 hemagglutinin gene. Compared with real-time RT-PCR, the sensitivities and specificities were 83.7% and 100% for Seeplex RT-PCR, 64.5% and 94.7% for Binax RAT, and 69.5% and 100% for SD RAT. The sensitivities of Seeplex RT-PCR, Binax RAT and SD RAT in patients aged over 21 years were 73.7%, 47.4% and 57.9%, respectively. The sensitivities of Seeplex RT-PCR, Binax RAT and SD RAT on the day of initial symptoms were mostly lower (68.8%, 56.3% and 31.3%, respectively). In conclusion, multiplex RT-PCR and RAT for the detection of H1N1 2009 were significantly less sensitive than real-time RT-PCR. Also, a negative RAT may require more sensitive confirmatory assays, because it cannot be ruled out from influenza infection.

Fe based (FeCSiBPCrMoAl) amorphous powder, which is a composition of iron blast cast slag, were produced by a gas atomization process, and sequently mixed with ductile Cu powder by a mechanical ball milling process. The Fe-based amorphous powders and the Fe-Cu composite powders were compacted by a spark plasma sintering (SPS) process. Densification of the Fe amorphous-Cu composited powders by spark plasma sintering of was occurred through a plastic deformation of the each amorphous powder and Cu phase. The SPS samples milled by AGO-2 under 500 rpm had the best homogeneity of Cu phase and showed the smallest Cu pool size. Micro-Vickers hardness of the as-SPSed specimens was changed with the milling processes.