Earticle

Background: This study focuses on the fabrication and characterization of quasi-hemispherical Cd0.9Zn0.1Te (CZT) detector for gamma-ray spectroscopy applications, aiming to contribute to advancements in radiation measurement and research. Materials and Methods: A CZT ingot was grown using the vertical Bridgman technique, followed by proper fabrication processes including wafering, polishing, chemical etching, electrode deposition, and passivation. Response properties were evaluated under various external bias voltages using gamma-ray sources such as Co-57, Ba-133, and Cs-137. Results and Discussion: The fabricated quasi-hemispherical CZT detector demonstrated sufficient response properties across a wide range of gamma-ray energies, with sufficient energy resolution and peak distinguishability. Higher external bias voltages led to improved performance in terms of energy resolution and peak shape. However, further improvements in defect properties are necessary to enhance detector performance under low bias conditions. Conclusion: This study underscores the efficacy of quasi-hemispherical CZT detector for gamma- ray spectroscopy, providing valuable insights for enhancing their capabilities in radiation research field.

Background: Cadmium zinc telluride (CZT) is a promising material because of a high detection efficiency, good energy resolution, and operability at room temperature. However, the cost of CZT dramatically increases as its size increases. In this study, to achieve a large effective volume with relatively low cost, an array structure comprised of individual virtual Frisch-grid CZT detectors was proposed. Materials and Methods: The prototype consisted of 2 × 2 CZTs, a holder, anode and cathode printed circuit boards (PCBs), and an application-specific integrated circuit (ASIC). CZTs were used and the non-contacting shielding electrode method was applied for virtual Frisch-grid effect. An ASIC was used, and the holder and the PCBs were fabricated. In the current system, because the CZTs formed a common cathode, a total of 5 channels were assigned for data processing. Results and Discussion: An experiment using 137Cs at room temperature was conducted for 10 minutes. Energy and timing information was acquired and the depth of interaction was calculated by the timing difference between the signals of both electrodes. Based on obtained three-dimensional position information, the energy correction was carried out, and as a result the energy spectra showed the improvements. In addition, a Compton image was reconstructed using the iterative method. Conclusion: The virtual Frisch-grid CZT detector based on the array structure was developed and the energy spectra and the Compton image were successfully acquired.

본 연구는 LIBS 기술을 적용한 도시광산의 경제 유발효과를 산업연관표를 이용하여 분석하였다. 특히 도시광산 산업이 폐기물 재생을 통해 경제 및 환경 관점의 편익을 기대하고 있으므로, 산업연관분석을 이용하여 도시광산 산업을 대상으로 유발효과를 추정하는 과정에서 생산유발, 고용유발 뿐만 아니라 에너지 수요·CO2 배출저감 측면에서의 효과도 추정하였다. 추정결과 LIBS 설비도입의경우에 생산유발계수는 1.25, 부가가치유발은 0.46, 취업유발은 10억 원당 4.56명, 고용유발은 10억원당 3.74명으로 나타났으며, LIBS 도입 도시광산산업 운영의 경우에 생산유발계수는 1.13, 부가가치유발계수는 0.50, 취업유발은 10억 원당 6.35명, 고용유발은 10억 원당 5.34명으로 나타났다. 또한LIBS 기술도입 도시광산산업 운영의 경우에 우리나라 전체 에너지투입액의 0.02%를 저감하며, 0.0003%의 CO2 eq.를 저감하는 것으로 나타나, LIBS 기술을 활용한 도시광산이 생산 및 고용 측면뿐만 아니라 에너지 및 CO2 배출저감 측면에서도 긍정적인 효과를 기대해볼 수 있음을 알 수 있었다.

This study analyzed the economic inducement effect of urban mining owing to the application of laser induced breakdown spectroscopy (LIBS) technology with input?output analysis by considering energy demand and CO2 emission reduction, as well as production and employment. The estimation result showed that, as a result of the installation of LIBS facilities, the production inducement coefficient is 1.25, the value-added inducement coefficient is 0.46, the job inducement is 4.56 persons per 1 billion KRW, and the employment inducement is 3.74 persons per 1 billion KRW. Owing to the operation of LIBS facilities, the production inducement coefficient is 1.13, the value-added inducement coefficient is 0.50, job inducement is 6.35 persons per 1 billion KRW, and the employment inducement coefficient is 5.34 persons per 1 billion KRW. In addition, the application of LIBS technology can induce positive effects in urban mining with respect to energy demand and CO2 emission reduction, as well as production and employment, by reducing 0.0003% of CO2 eq. and 0.02% of the total energy input.

Objective To identify the effective injection route for adult human bone marrow stromal cells into traumatic brain injured rats. Method The TBI rats were created by the lateral percussion model (HD1700, Dragonfly, Silver Spring, USA). Eight rats without stem cell transplantation were assigned to a control group. We performed adult human bone marrow stromal cell transplantation into the contralateral hemisphere (n=7), the ipsilateral brain lesion (n=8) and via a tail vein (n=11), respectively, at 24 hours after brain injury. For all of the groups, MRS (magnetic resonance spectroscopy) study, behavior tests, rotarod tests and Barnes maze tests were conducted on day 1, day 7, day 42 and day 84. Sixteen rats were randomly assigned and were sacrificed for immunohistochemical staining. Results At day 42 (p=0.048) and day 84 (p=0.031) after TBI, the ratio of N-acetylaspartate to creatine (NAA/Cr) of the ipsilateral hemisphere was decreased in the control group, as assessed by MRS, whereas the ratio was increased in the other groups. On the post hoc analysis, significant differences were obtained among the intravenous group and the control group for the NAA/Cr ratio of the ipsilateral hemisphere at day 84 after TBI (p=0.050). However, there was no significant improvement on the behavior test, the rotarod test and the Barnes maze test. The cells were positively stained with antibodies to MAB-1281 and to GFAP. Conclusion We confirmed that adult human bone marrow stromal cell transplantation induced an increase of the NAA/Cr ratio of the ipsilateral hemisphere at day 84 in the intravenous group. Therefore, we suggest the intravenous route is more effective for mesenchymal stem cell transplantation.

In Italy, buffalo mozzarella is a largely sold and consumed dairy product. The fraudulent adulteration of buffalo milk with cheaper and more available milk of other species is very frequent. In the present study, Fourier transform infrared spectroscopy (FTIR), in combination with multivariate analysis by partial least square (PLS) regression, was applied to quantitatively detect the adulteration of buffalo milk with cow milk by using a fully automatic equipment dedicated to the routine analysis of the milk composition. To enhance the heterogeneity, cow and buffalo bulk milk was collected for a period of over three years from different dairy farms. A total of 119 samples were used for the analysis to generate 17 different concentrations of buffalo- cow milk mixtures. This procedure was used to enhance variability and to properly randomize the trials. The obtained calibration model showed an R2 ≥ 0.99 (R2cal. = 0.99861; root mean square error of cross-validation [RMSEC] = 2.04; R2val. = 0.99803; root mean square error of prediction [RMSEP] = 2.84; root mean square error of cross-validation [RMSECV] = 2.44) suggesting that this method could be successfully applied in the routine analysis of buffalo milk composition, providing rapid screening for possible adulteration with cow’s milk at no additional cost.

Ketosis is associated with high milk yield during lactating or insufficient feed intake in lactating dairy cows. However, few studies have been conducted on the metabolomics of ketosis in Korean lactating dairy cows. The present study aimed to investigate the serum and urine metabolites profiling of lactating dairy cows through proton nuclear magnetic resonance (1H-NMR) spectroscopy and comparing those between healthy (CON) and subclinical ketosis (SCK) groups. Six lactating dairy cows were categorized into CON and SCK groups. All experimental Holstein cows were fed total mixed ration. Serum and urine samples were collected from the jugular vein of the neck and by hand sweeping the perineum, respectively. The metabolites in the serum and urine were determined using 1H-NMR spectroscopy. Identification and quantification of metabolites was performed by Chenomx NMR Suite 8.4 software. Metabolites statistical analysis was performed by Metaboanalyst version 5.0 program. In the serum, the acetoacetate level was significantly (p < 0.05) higher in the SCK group than in the CON group, and whereas acetate, galactose and pyruvate levels tended to be higher. CON group had significantly (p < 0.05) higher levels of 5-aminolevulinate and betaine. Indole-3-acetate, theophylline, p-cresol, 3-hydroxymandelate, gentisate, N-acetylglucosamine, N-nitrosodimethylamine, xanthine and pyridoxine levels were significantly (p < 0.05) higher in the urine of the SCK group than that in the CON group, which had higher levels of homogentisate, ribose, gluconate, ethylene glycol, maltose, 3-methyl-2-oxovalerate and glycocholate. Some significantly (p < 0.05) different metabolites in the serum and urine were associated with ketosis diseases, inflammation, energy balance and body weight. This study will be contributed useful a future ketosis metabolomics studies in Korea.

Background: Measuring the energy spectrum of γ rays to assess the exposure dose and identifying the leaked radioisotopes at the accident site and the surrounding environment is necessary in the case of an accident involving the leakage of radioactive material at a nuclear power plant or a radiation-related facility. High-purity germanium semiconductor detectors are utilized for γ-ray spectrometry due to their high energy resolution, but they exhibit a high initial and operational cost due to the need for a cooling mechanism. Materials and Methods: We improved the unfolding method for scintillators with a refined response function that involves the energy dependence of scintillation efficiency for secondary electrons produced by incident γ-ray interaction. Monte Carlo simulation code EGS5 with a mesh width of 5 keV in the energy range of 0–3 MeV was used to calculate response functions, assuming γ rays irradiated parallel to the detector sides. The unfolding algorithm involves an iterative approximation method, which is independent of initial guesses. Results and Discussion: The measurement accuracy of the γ-ray fluence rate was almost constant at <10% at ≥0.3 MeV caused by repeated measurements using 137Cs, 133Ba, 88Y, and 60Co radiation sources. Additionally, we confirmed linearity concerning the γ-ray intensity by changing the distance from the source to the detector. Conclusion: We verified that the unfolding method separated peaks for each γ-ray energy, although the difference in γ-ray energies was several tens of keV. Moreover, the accuracy of the unfolding method was almost constant and had linearity concerning γ-ray intensity.

The spectroscopy toolkit has been developed and tested. The toolkit consists of a CsI(Tl)/PIN diode detector, integrated electronics, and a multi‐channel‐analyzer and its size was 40 cm(width) by 20 cm(length) by 6 cm(high). It is compact, very portable and simpler and cheaper compared to the conventional spectroscopy system. The gamma energy resolutions of the toolkit were 7.9% for the 660 keV of 137Cs and 4.9% for 1,332 keV of 60Co respectively. The linearity for gamma energies was good. When the energy spectrum of a ceramic sample containing 232Th was measured with the spectroscopy toolkit for 20 minutes, there were significant peaks of the heavy metal. These results show that the resolution of the spectroscopy toolkit is sufficient to accumulate a quality spectrum in a few minutes by using weak, encapsulated commercial sources. Furthermore a toolkit experiment that how to measure energy spectra using the toolkit, and how to identify specific isotopes in a pottery piece, could be widely adopted for education and even for more sophisticated and higher level experiments.

We present terahertz optical properties of GdBa2Cu3O7-x (GdBCO) superconducting thin films. GdBCO films with a thickness of about 105 nm were grown on a LaAlO3 (LAO) single crystal substrate using a conventional pulsed laser deposition (PLD) technique. Using an Ar ion milling system, the thickness of the GdBCO film was reduced to 58 nm, and its surface was also smoothened. Terahertz (THz) transmission spectra through two different GdBCO films are measured over the range between 0.2 and 1.5 THz using THz time domain spectroscopy. Interestingly, the THz transmission of the thinner GdBCO film has been increased to six times larger than that of the thicker one, while the thinner film is still maintaining its superconducting property at below 90 K.

Background: We are developing L-band and S-band microwave dielectric absorption systems aiming novel dosimetry using DNAs, such as plasmid DNA and genomic DNA, and microwave technology. Materials and Methods: Each system is composed of a cavity resonator, analog signal generator, circulator, power meter, and oscilloscope. Since the cavity resonator is sensitive to temperature change, we have made great efforts to prevent the fluctuation of temperature. We have developed software for controlling and measurement. Results and Discussion: By using this system, we can measure the resonance frequency, f, and Δ Q (Q is a dimensionless parameter that describes how under-damped an oscillator or resonator is, and characterizes a resonator's bandwidth relative to its center frequency) within about 3 minutes with high accuracy. Conclusion: This system will be expected to be applicable to DNAs evaluations and to novel dosimetric system.

The development of spectroscopic gamma-ray detectors requires the optimization of several factors, such as the growth of a relatively thick (>1 mm), defect-free, and compositionally uniform radiation-sensitive medium, the extraction of radiation-induced carriers from the medium without loss, a good response linearity between the radiation energy and the number of collected carriers, and the long-term stability in an ambient environment. We review recent advances in the structural design of novel gamma detector systems based on nanoparticles (NPs), including nanocrystals (NCs). The use of NPs in gamma-ray detection has been attracting great attention recently, due to their enhanced optical properties, favorable carrier multiplication condition, low-cost fabrication, and improved chemical properties with stability. Many different fabrication approaches have been adopted for indirect and direct detectors. The indirect detector can be realized by both luminescent NCs and non-luminescent (or weakly luminescent) NPs with high atomic numbers. A proper polymerization process leads to a uniform and high loading of NPs in a large volume, which protects the NPs from oxidation. Furthermore, additional types of composites, including fluorescent dyes or cosolvent, may facilitate efficient charge carrier transfer to linearly convert the incident gamma-ray energy into the number of scintillation photons with negligible loss. The direct detector is implemented by interconnecting NCs with high packing density and mitigating crack formation to extract radiation-induced charge carriers to electrodes across millions of NCs and interfaces. In addition, controlling the NC size, ligand chain length, and NC dispersion state determines the leakage current level. To the best of our knowledge, several studies of NC-based gamma-ray detectors have recently demonstrated gamma spectroscopy capability in the last 10 years, showing improved energy resolution comparable to single-crystal gamma-ray detectors. This review will provide an in-depth overview of the current status and challenges in developing NP-based gamma detectors.

Since the discovery of iron-based superconductors in 2008, extensive and intensive studies have been performed to find the microscopic theory for the high temperature superconductivity in the materials. Electronic structure is the basic and essential information that is needed for the microscopic theory. Experimentally, angle resolved photoelectron spectroscopy (ARPES) is the most direct tool to obtain the electronic structure information, and therefore has played a vital role in the research. In this review, we review what has been done so far and what is needed to be done in ARPES studies of iron-based superconductors in search of the microscopic theory. This review covers issues on the band structure, orbital order/fluctuation, and gap structure/symmetries as well as some of the theories.