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- Author or Editor: Hyun Cho x
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Abstract
The hydrogen concentration for the reference material low-alloy steel was estimated using prompt gamma neutron activation analysis. The hydrogen concentration had a range of 0.91–1.14 mg/kg as measured by the prompt gamma activation method but the reference value was about 1.0 mg/kg as measured by the ICP/AES method. The relative error appeared to be 14% and the differences showed as the background by blank. The standard reference material (NIST SRM) was used for the analytical control.
Background and aims
Overindulgence in Internet gaming, which is related to rapid development of the online game industry, can cause a psychiatric disorder known as Internet gaming disorder (IGD). The number of adolescents with IGD is on the rise in countries with developed Internet technologies, such as South Korea. Therefore, it is important to develop biomarkers to detect patients at high risk of IGD. This study investigated expression levels of proteins in the blood of adolescents to provide insight into the development of biomarkers.
Methods
We collected blood samples from 73 subjects [40 healthy adolescents (Internet gaming control, IGC) and 33 adolescents with IGD] between 13:00 and 15:00. We analyzed the expression levels of orexin A, oxytocin, cortisol, melatonin, BDNF, sICAM-1, RANTES, and NCAM using multiplex assay kits.
Results
Orexin A was significantly (p = .016) elevated in the IGD group and the expression levels of melatonin tended to be higher (p = .055) in the IGD group. On the other hand, increased Internet gaming time in the IGD group was negatively correlated (p = .041) with expression of BDNF. On the contrary, sICAM-1 associated with inflammation exhibited the tendency of the positive correlation (p = .073) with Internet gaming time in the IGD group.
Discussion and conclusions
We identified elevation of orexin A in the peripheral blood of adolescents with IGD and a negative correlation between Internet gaming time and BDNF in adolescents with IGD. Our results provide useful information to understand the pathophysiology of IGD in adolescents.
Abstract
In this study, polycardanol, which was synthesized by enzymatic oxidative polymerization of thermally treated cashew nut shell liquid (CNSL) using fungal peroxidase, was partially or fully cured using methyl ethyl ketone peroxide (MEKP) as initiator and cobalt naphthenate (Co-Naph) as accelerator. The curing behavior of polycardanol was extensively investigated in terms of curing temperature, curing time, concentration of initiator and accelerator, and the monomer-to-polymer conversion of polycardanol by means of differential scanning calorimetry (DSC). The curing behavior significantly depends on the thermal condition given and it was monitored with the change of the exotherms as a function of temperature. The optimal conditions for fully curing polycardanol are 1 wt% MEKP, 0.2 wt% Co-Naph, curing time 120 min, and curing temperature 200 °C. This study suggests that a polycardanol with high monomer-to-polymer conversion would be useful for processing a polycardanol matrix composite under the optimal conditions of curing.
Summary
A prompt gamma activation analysis facility has been constructed on the ST1 horizontal beam port at the HANARO research reactor, KAERI in 2003. The detector system consists of a high-purity Ge detector surrounded by BGO/NaI(Tl) scintillators as an annulus type to reject the Compton scattered photons. Detection sensitivity for boron was obtained from the prompt gamma-ray spectra of boric acid, B(OH)3, containing 0.1-65 μg boron. The net peak for the calculation of the boron concentration was obtained by eliminating the sodium 472 keV peak, involved in the boron 478 keV peak. The biological samples used are NIST SRMs such as Peach Leaves, Apple Leaves, Tomato Leaves, Spinach Leaves, Total Diet, Typical Diet, Oyster Tissue and Corn Bran, etc. The measured values for high boron concentration showed up to a 3% of the relative, but in a low concentration below 5 ppm, present values were higher than the certified ones.
Abstract
The prediction of the adsorption behavior of natural composite materials was studied by a single mineral approach. The adsorption of U(VI) on single minerals such as goethite, hematite, kaolinite and quartz was fully modeled using the diffuse-layer model in various experimental conditions. A quasi-thermodynamic database of surface complexation constants for single minerals was established in a consistent manner. In a preliminary work, the adsorption of a synthetic mixture of goethite and kaolinite was simulated using the model established for a single mineral system. The competitive adsorption of U(VI) between goethite and kaolinite can be well explained by the model. The adsorption behavior of natural composite materials taken from the Koongarra uranium deposit (Australia) was predicted in a similar manner. In comparison with the synthetic mixture, the prediction was less successful in the acidic pH range. However, the model predicted well the adsorption behavior in the neutral to alkaline pH range. Furthermore, the model reasonably explained the role of iron oxide minerals in the adsorption of U(VI) on natural composite materials.
Abstract
Background and aims
Problematic smartphone use (PSU) is growing rapidly among teens. It has similar presentations as other behavioral addictions in terms of excessive use, impulse control problems, and negative consequences. However, the underlying neurobiological mechanisms remain undiscovered. We hypothesized that structural changes in the striatum might serve as an important link between alteration in glutamate signaling and development of PSU.
Methods
Among 88 participants, twenty (F:M, 12:8; age 16.2 ± 1.1) reported high scores in the smartphone addiction proneness scale (SAPS) with a cut-off score of 42; the other 68 (F:M, 19:49; age 15.3 ± 1.7) comprised the control group. Sociodemographic data and depression, anxiety, and impulsivity traits were measured. Striatal volumes (caudate, putamen, and nucleus accumbens) were estimated from T1 imaging data. Serum glutamate levels were estimated from peripheral blood samples. Group comparisons of each data were performed after controlling for age and gender. Mediation analyses were conducted to test the indirect effects of glutamate level alteration on PSU through striatal volumetric alteration.
Results
The PSU group showed a decrease in both caudate volumes than the control group. Left caudate volume was positively correlated with serum glutamate level, and negatively with impulsivity traits and SAPS scores. The mediation model revealed a significant indirect effect of serum glutamate on SAS scores through the reduced left caudate volume.
Discussion and conclusions
This study suggests that altered glutamatergic neurotransmission may be associated with PSU among teens, possibly through reduced left caudate volume. Current findings might support neural mechanisms of smartphone addiction.
Abstract
Background and aims
Although the Internet has provided convenience and efficiency in many areas of everyday life, problems stemming from Internet use have also been identified, such as Internet gaming disorder (IGD). Internet addiction, which includes IGD, can be viewed as a behavioral addiction or impulse control disorder. This study investigated the altered functional and effective connectivity of the core brain networks in individuals with IGD compared to healthy controls (HCs).
Methods
Forty-five adults with IGD and 45 HCs were included in this study. To examine the brain networks related to personality traits that influence problematic online gaming, the left and right central executive network (CEN) and the salience network (SN) were included in the analysis. Also, to examine changes in major brain network topographies, we analyzed the default mode network (DMN).
Results
IGD participants showed lower functional connectivity between the dorsal lateral prefrontal cortex (DLPFC) and other regions in the CEN than HC participants during resting state. Also, IGD participants revealed reduced functional connectivity between the dorsal anterior cingulate cortex and other regions in the SN and lower functional connectivity in the medial prefrontal cortex of the anterior DMN. Notably, in IGD individuals but not HC individuals, there was a positive correlation between IGD severity and effective connectivity and a positive correlation between reward sensitivity and effective connectivity within the ventral striatum of the SN.
Conclusions
Problematic online gaming was associated with neurofunctional alterations, impairing the capacity of core brain networks.
Background and aims
Problematic Internet game use is an important social issue that increases social expenditures for both individuals and nations. This study identified predictors and patterns of problematic Internet game use.
Methods
Data were collected from online surveys between November 26 and December 26, 2014. We identified 3,881 Internet game users from a total of 5,003 respondents. A total of 511 participants were assigned to the problematic Internet game user group according to the Diagnostic and Statistical Manual of Mental Disorders Internet gaming disorder criteria. From the remaining 3,370 participants, we used propensity score matching to develop a normal comparison group of 511 participants. In all, 1,022 participants were analyzed using the chi-square automatic interaction detector (CHAID) algorithm.
Results
According to the CHAID algorithm, six important predictors were found: gaming costs (50%), average weekday gaming time (23%), offline Internet gaming community meeting attendance (13%), average weekend and holiday gaming time (7%), marital status (4%), and self-perceptions of addiction to Internet game use (3%). In addition, three patterns out of six classification rules were explored: cost-consuming, socializing, and solitary gamers.
Conclusion
This study provides direction for future work on the screening of problematic Internet game use in adults.
Abstract
We measured neutron total cross-sections of natural niobium in the neutron energy region from 0.05 to 300 eV by using the time-of-flight method at the Pohang Neutron Facility, which consists of an electron linear accelerator, a water-cooled tantalum target with a water moderator, and a 12-m long time-of-flight path. A 6Li–ZnS(Ag) scintillator with a diameter of 12.5 cm and a thickness of 1.6 cm was used as a neutron detector, and a high purity natural niobium metallic disc with a diameter of 8.0 cm and a thickness of 15.0 mm thickness was used for the neutron transmission measurement. Notch filters composed of Co, In, Cd were used to estimate the background level and to calculate the length of neutron flight path. In order to reduce the gamma-ray background from bremsstrahlung and from neutron capture, we used a neutron-gamma separation system based on their different pulse shapes. The present measurement was compared with the existing experimental and the evaluated data. The resonance parameters of 93Nb isotope were obtained from the transmission by using the SAMMY code and were compared with other previous results.
Abstract
We measured the isomeric yield ratios for the photonuclear reactions of 93Nb(γ,4n)89m,gNb and natMo(γ,xnp)95m,gNb by using the activation method. The high-purity 93Nb and natMo metallic foils in disc shape were irradiated with uncollimated bremsstrahlung beams of 50-, 60-, and 70-MeV generated from an electron linear accelerator in Pohang Accelerator Laboratory. The induced activities in the irradiated foils were measured by the high-resolution γ-ray spectrometry with a calibrated high-purity Germanium (HPGe) detector coupled to a PC-based 4 K multichannel analyzer. The reaction 93Nb(γ,4n)89m,gNb was studied for the first time which has no comparable literature data. The result of 95m,gNb isomeric pair was measured based on (γ,p), (γ,np), and (γ,2np) reactions which is the first measurement at the intermediate energy region of 50–70-MeV with a natMo target.
