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The purpose of this study is to perform radiation monitoring by acquiring gamma images and real-time optical images for 99mTc vial source using charge couple device (CCD) cameras equipped with the proposed compact gamma camera. The compact gamma camera measures 86 × 65 × 78.5 mm3 and weighs 934 g. It is equipped with a metal 3D printed diverging collimator manufactured in a 45° field of view (FOV) to detect the location of the source. The circuit's system uses system-on-chip (SoC) and field-programmable-gate-array (FPGA) to establish a good connection between hardware and software. In detection modules, the photodetector (multi-pixel photon counters) is tiled at 8 × 8 to expand the activation area and improve sensitivity. The gadolinium aluminium gallium garnet (GAGG) measuring 0.5 × 0.5 × 3.5 mm3 was arranged in 38 × 38 arrays. Intrinsic and extrinsic performance tests such as energy spectrum, uniformity, and system sensitivity for other radioisotopes, and sensitivity evaluation at edges within FOV were conducted. The compact gamma camera can be mounted on unmanned equipment such as drones and robots that require miniaturization and light weight, so a wide range of applications in various fields are possible.

This study quantitatively evaluated the source term of a linear accelerator according to target thickness for a 6-20 MeV electron beam using MCNP6. The elements of the target were tungsten and copper, and a composite target and single target were simulated by setting different thickness parameters depending on energy. The accumulation of energy generated through interaction with the collided target was evaluated at 0.1-mm intervals, and F6 tally was used. The results indicated that less than 3% reference error was maintained according to the MCNP recommendations. At 6, 8, 10, 15, 18, and 20 MeV, the energy accumulation peaks identified for each target were 0.3 mm in tungsten, 1.3 mm in copper, 1.5 mm in copper, 0.5 mm in tungsten, 0.5 mm in tungsten, and 0.5 mm in tungsten. For 8 and 10 MeV in a single target consisting only of copper, the movement of electrons was confirmed at the end of the target, and the proportion of escaped electrons was 0.00011% and 0.00181%, respectively.

The present study investigated the cryogenic mechanical properties and microstructure of CrCoNi medium entropy alloy (MEA) fabricated by selective laser melting (SLM) with hot isostatic pressing (HIP). The SLM processing parameters were optimized with respect to the relative density and micro-hardness of as-built CrCoNi specimens. The cryogenic (150 K) deformation mechanisms (compared to room (298 K) temperature) of SLM CrCoNi MEA were characterized by uniaxial tensile test, electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). At 150 K, it reveals superior mechanical properties with the noticeable increase in both strength and ductility by 6.5% and 10.0% (as-built), 22.7% and 6.6% (HIP-treated), respectively. It is found that the high cooling rate of 3.2 × 106 K/s obtained from the simulation results in the fine microstructure and high dislocation density, accordingly the high yield strength of SLM CrCoNi MEA. The steady work hardening, which postpones the onset of necking instability, is attributed to the pronounced dislocation activity and deformation twinning. In addition, a new phase with hexagonal closed-packed (HCP) substructure is apparently observed. Thus, a synergistic effect of dislocations, deformation twinning and HCP substructures contributes to the simultaneous enhancement of strength and ductility. These findings reveal that the CrCoNi MEA fabricated by SLM exhibits an excellent strength and ductility at cryogenic temperature. Furthermore, the SLM CrCoNi MEA with HIP shows significant improvement in the ductility with exceptional strength at 150 K. It demonstrates that a combination of SLM and HIP promotes the CrCoNi MEA to be promising for the cryogenic applications.

An interfacial microstructural study was carried out to clarify the hardening mechanism of an as-built Co–Cr alloy fabricated by selective laser melting (SLM). Using transmission electron microscopy, we found a unique martensitic lamellar microstructure with a specific orientation relationship between the α-Co and ε-Co phases; specifically, a nanoscale microstructure consisting of (111)α-Co//(0002¯)ε-Co and [01¯1]α-Co//[1¯21¯0]ε-Co was formed on the Co–Cr alloy. The Co–Cr alloy fabricated by SLM with a martensitic microstructure achieved a Vickers hardness value of approximately 369.36 ± 11.86 HV without any secondary-phase particles such as carbides.

The root of Smilax china L. is used in traditional Korean medicine. We found that the Smilax china L. root extract has strong antimicrobial activity against two Cutibacterium acnes strains (KCTC 3314 and KCTC 3320). The aim of this study was to identify the beneficial properties of Smilax china L. extracts for their potential use as active ingredients in cosmetics for the treatment of human skin acne. The high-performance liquid chromatography (HPLC) and liquid chromatography-hybrid quadrupole time-of-flight mass spectrometry (LC/QTOF/MS) methods were used to obtain the profile of secondary metabolites from the ethyl acetate-soluble fraction of the crude extract. Agar diffusion and resazurin-based broth microdilution assays were used to evaluate antimicrobial activity and minimum inhibitory concentrations (MIC), respectively. Among the 24 metabolites, quercetin, resveratrol, and oxyresveratrol were the most potent compounds against Cutibacterium acnes. Minimum inhibitory concentrations of quercetin, resveratrol, and oxyresveratrol were 31.25, 125, and 250 μg/mL, respectively.

By controlling specific process conditions in the selective laser melting (SLM) of commercially pure Ti powder (Grade 1), a porous structure was fabricated to achieve a high specific surface area. Additive manufacturing was employed through SLM to control the energy density to be lower than that required for the complete melting of Ti powders by operating at a power of 80 to 480 W and a scan speed of 1750 to 10,500 mm/s. The range of the process conditions, i.e., complete melting, partial melting, and unmelted, was determined based on the observations of the microstructure parallel to the building direction. When the powders were pre-sintered and not melted under specific process conditions with an energy density lower than that required for complete melting, porous microstructures were formed with open pores. In addition, interfacial microstructural studies were conducted to confirm the presence of residual powder, which settled onto the strut, resulting in a higher specific surface area. These indicate that the SLM process can enhance the porosity, even with a specific design of lattice structures, as fluidic materials are expected to flow through the open porous structure.

A method for stably purifying a functional dye, phycocyanin from Spirulina platensis was developed by a hexane extraction process combined with high pressure. This was necessary because this dye is known to be very unstable during normal extraction processes. The purification yield of this method was estimated as 10.2%, whose value is 3%–5% higher than is the case from another conventional separation method using phosphate buffer. The isolated phycocyanin from this process also showed the highest purity of 0.909 based on absorbance of 2.104 at 280 nm and 1.912 at 620 nm. Two subunits of phycocyanin namely α-phycocyanin (18.4 kDa) and β-phycocyanin (21.3 kDa) were found to remain from the original mixtures after being extracted, based on SDS-PAGE analysis, clearly demonstrating that this process can stably extract phycocyanin and is not affected by extraction solvent, temperature, etc. The stability of the extracted phycocyanin was also confirmed by comparing its DPPH (α,α-diphenyl-β-picrylhydrazyl) scavenging activity, showing 83% removal of oxygen free radicals. This activity was about 15% higher than that of commercially available standard phycocyanin, which implies that the combined extraction method can yield relatively intact chromoprotein through absence of degradation. The results were achieved because the low temperature and high pressure extraction effectively disrupted the cell membrane of Spirulina platensis and degraded less the polypeptide subunits of phycocyanin (which is a temperature/pH-sensitive chromoprotein) as well as increasing the extraction yield.

We evaluated a more practical and cost-effective immobilization carriers for ethanol production using the yeast Saccharomyces cerevisiae. Three candidate materials—rice hull, rice straw, and sawdust—were tested for their cell-adsorption capacity and operational durability. Derivatizations of rice hull, rice straw, and sawdust with the optimal concentration of 0.5 M of 2-(diethylamino)ethyl chloride hydrochloride (DEAE · HCI) resulted in > 95% adsorption of the initial yeast cells at 2 hr for DEAErice hull and DEAE-sawdust and in only approximately 80% adsorption for DEAE-rice straw. In addition, DEAE-sawdust was found to be a more practical carrier for immobilizing yeast cells in terms of operational durability in shaking flask cultures with two different speeds of 60 and 150 rpm. Furthermore, the biosorption isotherms of DEAE-rice hull, -rice straw, and -sawdust for yeast cells revealed that the Qmax of DEAE-sawdust (82.6 mg/g) was greater than that of DEAE-rice hull and DEAE-rice straw. During the 404-hr of continuous column reactor operation using yeast cells immobilized on DEAE-sawdust, no serious detachment of the yeast cells from the DEAE-sawdust was recorded. Ethanol yield of approximately 3.04 g/L was produced steadily, and glucose was completely converted to ethanol at a yield of 0.375 g-ethanol/g-glucose (73.4% of the theoretical value). Thus, sawdust is a promising practical immobilization carrier for ethanol production, with significance in the production of bioethanol as a biofuel. [ABSTRACT FROM AUTHOR]

We investigated a novel process for production of ethanol from glycerol using the yeast Pachysolen tannophilus. After optimization of the fermentation medium, repeated-batch flask culture was performed over a period of 378 hr using yeast cells immobilized on Celite. Our results indicated that the use of Celite for immobilization of P. tannophilus was a practical approach for ethanol production from glycerol, and should be suitable for industrial ethanol production. [ABSTRACT FROM AUTHOR]

A method for stably purifying a functional dye, phycocyanin from Spirulina platensis was developed by a hexane extraction process combined with high pressure. This was necessary because this dye is known to be very unstable during normal extraction processes. The purification yield of this method was estimated as 10.2%, whose value is 3%-5% higher than is the case from another conventional separation method using phosphate buffer. The isolated phycocyanin from this process also showed the highest purity of 0.909 based on absorbance of 2.104 at 280 nm and 1.912 at 620 nm. Two subunits of phycocyanin namely ɑ-phycocyanin (18.4 kDa) and ß-phycocyanin (21.3 kDa) were found to remain from the original mixtures after being extracted, based on SDS-PAGE analysis, clearly demonstrating that this process can stably extract phycocyanin and is not affected by extraction solvent, temperature, etc. The stability of the extracted phycocyanin was also confirmed by comparing its DPPH (ɑ,ɑ-diphenyl-ß-picrylhydrazyl) scavenging activity, showing 83% removal of oxygen free radicals. This activity was about 15% higher than that of commercially available standard phycocyanin, which implies that the combined extraction method can yield relatively intact chromoprotein through absence of degradation. The results were achieved because the low temperature and high pressure extraction effectively disrupted the cell membrane of Spirulina platensis and degraded less the polypeptide subunits of phycocyanin (which is a temperature/pH-sensitive chromoprotein) as well as increasing the extraction yield. [ABSTRACT FROM AUTHOR]

A method for measuring the ethanol concentration in a yeast culture broth was developed using both microtubes and a 96-deepwell microplate. The strategy involved first the solvent extraction of ethanol from the yeast culture broth and measurements of the ethanol concentration using the dichromate oxidation method. Particular focus was made on selecting the extraction solvent as well as determining the measurable range of ethanol concentrations using this solvent extraction-dichromate oxidation method. This method was developed as an assay format in 2.0-ml microtubes and 1.2-ml 96-deepwell microplates, and the ethanol concentration in the batch cultures and fed-batch fermentations was measured. Tri- n-butyl phosphate [non-alcoholic solvent, density = 0.9727, solubility in water = 0.028% (w/v)] was used for solvent extraction when measuring the ethanol concentration from the yeast culture broth. The maximum detectable ethanol concentration was 8% (v/v) when 10 g potassium dichromate in 100 ml of 5 M sulfuric acid was used. The concentrations determined from the solvent extraction-dichromate oxidation methods were remarkably similar to those of gas chromatography in which samples were prepared from seven experiments, such as four batch cultures and three fed-batch fermentations. [ABSTRACT FROM AUTHOR]

In this study, we utilized a catabolite repressor to improve the enzymatic activity of recombinant β-galactosidase inclusion bodies (IBs) produced in Escherichia coli under the araBAD promoter system. Specifically, we employed methyl α- d-glucopyranoside (α-MG) to lower the transcription rate of the β-galactosidase structural gene. In deepwell microtiter plate and lab-scale fermentor culture systems, we demonstrated that the addition of α-MG after induction improved the specific β-galactosidase production, even though β-galactosidase was still produced as an IB. Particularly, the addition of 0.0025% α-MG led to the most significant increase in the specific activity of the β-galactosidase. Interestingly, the β-galactosidase IBs obtained in the presence of 0.0025% α-MG were more loosely packed, as determined by IB solubilization in guanidine hydrochloride solution. We propose that the reduced gene transcription rate was responsible for the increased specific β-galactosidase activity and the loose packing that characterized the IBs produced in the presence of α-MG. This principle could be applied throughout the enzyme bioprocessing industry in order to enhance the activity of aggregate-prone enzymes within IBs. [ABSTRACT FROM AUTHOR]

In an effort to refine the composition and properties of existing hard metals, (W,Ti)C–20 wt% Co cermets have been developed. The present research reports the mechanical and tribological properties of these novel materials. Single-step as well as two-stage and three-stage sintering experiments were conducted on the cermets, processed from the (W,Ti)C solid solution powders. For property comparison, premixed WC/TiC powders were used to fabricate a reference (W,Ti)C–20 wt% Co cermet material. Higher sintered density (9.57 g/cm3) as well as better elastic modulus (467 GPa) and hardness (∼17 GPa) were obtained after three-stage sintering of solid solution powders. In order to evaluate the tribological properties, the fretting wear experiments (mode I, linear relative tangential displacement) were performed against bearing steel for varying normal load in the range of 2–10 N. The experimental results reveal that the steady-state coefficient of friction (COF) varies between 0.50 and 0.65, and a lower COF is recorded at 10 N load for cermets processed from solid solution powders. Under varying tribological conditions, the cermets sintered from solid solution powders exhibit low wear depth (∼1–4 μm) and lower wear rate (7 × 10−7–18 × 10−7 mm3·(N·m)−1 when compared with cermet prepared from the premixed WC/TiC starting powders (wear rate ∼14 × 10−7–22 × 10−7 mm3·(N·m)−1). The wear rate data are critically evaluated based on the phenomenological models. Broadly, abrasive wear is the dominant wear mechanism, and limited contribution from localized spalling of tribolayer and tribochemical wear was also observed. [ABSTRACT FROM AUTHOR]

In this study, a dissolved oxygen (DO)-stat fed-batch process was conducted in a pressurized 75-L bioreactor, resulting in the production of the short version of human leukotactin-1 (shLkn-1) using Pichia pastoris as the host, with control of the DO-stat profile and an extension of the recombinant shLkn-1 production phase. By regulation of the exhaust-gas valve, we were able to maintain the vessel pressure at up to 120 kPa, in order to overcome DO limitations associated with the use of the DO-stat. The lowest DO value was adjusted by varying the feed pump speed, allowing us to control the DO-stat profile. This principle was successfully applied to both glycerol feeding during the growth phase and methanol feeding for the induction of shLkn-1. The extension of the methanol induction phase to a total of 192 h of culture time resulted in a shLkn-1 concentration of 2.5 g/L, and a total of 102 g of cumulative production. During this extended induction period, the C-terminal residue of shLkn-1 was truncated and this was confirmed by both reverse-phase HPLC and mass spectrometry. [ABSTRACT FROM AUTHOR]

An abstract of the paper "Addition of Repressor in Inducible Promoter System Improves Soluble Expression of Recombinant Protein in E. Coli," by Kyung-Hwan Jung, is presented.

Apolipoprotein(a) (apo(a)) contains tandemly repeated kringle domains that are closely related to plasminogen kringle 4, followed by a single kringle 5-like domain and an inactive protease-like domain. Recently, the anti-angiogenic activities of apo(a) have been demonstrated both in vitro and in vivo. However, its effects on tumor angiogenesis and the underlying mechanisms involved have not been fully elucidated. To evaluate the anti-angiogenic and anti-tumor activities of the apo(a) kringle domains and to elucidate their mechanism of action, we expressed the last three kringle domains of apo(a), KIV-9, KIV-10, and KV, in Escherichia coli. The resultant recombinant protein, termed rhLK68, exhibited a dose-dependent inhibition of basic fibroblast growth factor-stimulated human umbilical vein endothelial cell proliferation and migration in vitro and inhibited the neovascularization in chick chorioallantoic membranes in vivo. The ability of rhLK68 to abrogate the activation of extracellular signal-regulated kinases appears to be responsible for rhLK68-mediated anti-angiogenesis. Furthermore, systemic administration of rhLK68 suppressed human lung (A549) and colon (HCT15) tumor growth in nude mice. Immunohistochemical examination and in situ hybridization analysis of the tumors showed a significant decrease in the number of blood vessels and the reduced expression of vascular endothelial growth factor, basic fibroblast growth factor, and angiogenin, indicating that suppression of angiogenesis may have played a significant role in the inhibition of tumor growth. Collectively, these results suggest that a truncated apo(a), rhLK68, is a potent antiangiogenic and anti-tumor molecule. [ABSTRACT FROM AUTHOR]

An agar-degrading marine bacterium identified as a novel member of the family Flavobacteriaceae (strain S85) was isolated from seawater in Micronesia. The sequenced strain S85 genome is composed of 3,384,629 bp in a circular chromosome, which includes 2,883 complete open reading frames. [ABSTRACT FROM AUTHOR]