An alternative proposal for the regulatory framework of the large accelerator facilities in the Korean Nuclear Safety Act.

Large accelerator facilities for scientific research and particle accelerators for radiotherapy have been constructed in Korea. The environments requiring radiological protection procedures have changed substantially and the legal requirements have also increased. However, the same regulatory criteria that are applied to small radiation-generating devices also apply to large accelerator facilities. This study evaluates an approach that uses new criteria based on radiological risk to classify different types of large accelerator facilities. To inform this study, regulations and licensing procedures adopted in various countries were reviewed. The radiological risks from different types of particle accelerators and different types of accelerated particles were investigated in relation to current and planned large accelerators in Korea. The investigation was based on neutron yield and induced radioactivity calculations undertaken using the Monte-Carlo code FLUKA. Based on this analysis, we propose two categories for large accelerator facilities. In the process of the facility construction through to getting an operation permit, we also propose a graded approach, which would require changes in the Korean Nuclear Safety Act. A two-step licensing procedure with a prior review and a final permit for accelerator operation is very practical and conservative in the view of radiation protection. The review process for the revision of the Nuclear Safety Act is currently in progress and a major aspect of this revision reflects the results of this study.

Brittle Fracture Behavior of Sn-Ag-Cu Solder Joints with Ni-Less Surface Finish via Laser-Assisted Bonding.

In this study, we investigated the brittle fracture behavior of Sn-3.0Ag-0.5Cu (SAC305) solder joints with a Direct Electroless Gold (DEG) surface finish, formed using laser-assisted bonding (LAB) and mass reflow (MR) techniques. Commercial SAC305 solder balls were used to ensure consistency. LAB increases void fractions and coarsens the primary ß-Sn phase with higher laser power, resulting in a larger eutectic network area fraction. In contrast, MR produces solder joints with minimal voids and a thicker intermetallic compound (IMC) layer. LAB-formed joints exhibit higher high-speed shear strength and lower brittle fracture rates compared to MR. The key factor in the reduced brittle fracture in LAB joints is the thinner IMC layer at the joint interface. This study highlights the potential of LAB in enhancing the mechanical reliability of solder joints in advanced electronic packaging applications.

Corrosive Esophageal Injury due to a Commercial Vinegar Beverage in an Adolescent.

Although gastroesophageal damage is commonly induced by accidental drinking of a strong acid or alkali, damage due to the consumption of a vinegar beverage is not well known. We report a case of corrosive esophageal ulcer found in an adolescent consuming a vinegar drink daily. A 15-year-old male visited the emergency room presenting with hematemesis and severe epigastric pain. Multiple longitudinal ulcers, concurrent mucosal hemorrhage, and denuded mucosa were noted in the whole of the esophagus via an endoscopic examination. He had been drinking a vinegar beverage daily without sufficient dilution. The patient was treated with corticosteroid, antibiotic therapy, and mucosa protecting alginate medication and was asked to fast for a week. The follow-up endoscopy showed improvement of the esophageal injuries. Overall, continuous consumption of a vinegar beverage can result in acidic burns and destruction of the surface of the upper gastrointestinal tract. Therefore, vinegar beverages should be considered as corrosive agents.

Incidentally Discovered Solitary Gastrointestinal Polyp with Pathological Significance in Children: Four Case Reports.

Most solitary gastrointestinal (GI) polyps in children are either inflammatory or hamartomatous. Solitary hyperplastic polyp, sentinel polyp and solitary adenomatous polyp have been occasionally diagnosed in adults, but very rarely reported in Korean children. We recently came across a case with adenomatous polyp in the colon, a case with hyperplastic polyp beneath the gastroesophageal junction, a case with hyperplastic polyp in the prepyloric area, and a case with sentinel polyp in the distal esophagus, which are unusual pathologic types in children. These mucosal lesions were diagnosed incidentally during elective endoscopic examinations for GI symptoms. Most polyps do not cause significant symptoms, so the diagnosis might be delayed, especially in children, in whom GI endoscopy is not commonly performed for screening purpose as in the adults.

Draft Genome Sequence of Fusobacterium nucleatum subsp. animalis ChDC F324, Isolated from a Human Subgingival Plaque in the Republic of Korea.

Five subspecies of Fusobacterium nucleatum have been classified: animalis, nucleatum, polymorphum, vincentii, and fusiforme. F. nucleatum subsp. animalis ChDC F324 (KCOM 1325) was isolated from a human subgingival plaque in the Republic of Korea. Here, we report the draft genome sequence of the strain.

Structure and expression of MdFBCP1, encoding an F-box-containing protein 1, during Fuji apple (Malus domestica Borkh.) fruit ripening.

From database comparisons of 1,117 expressed sequence tags (ESTs) generated from ripened Fuji apple fruits, we identified ten ubiquitin (Ub)-related genes. RNA gel-blot analysis suggests that these Ub-related genes are induced by at least four distinct signaling pathways in fruits. In this study, we analyzed structure and expression of MdFBCP1, encoding an F-box-containing protein 1, in Fuji apples. MdFBCP1 transcript was predominantly expressed in the fully ripened climacteric fruits, in which serge of ethylene production occurred. The MdFBCP1 gene was also activated effectively in response to exogenous ethylene treatment, with the induction pattern being comparable to those of ACC oxidase and beta-cyanoalanine synthase. Thus, it seems likely that the expression of MdFBCP1 is closely associated with a climacteric ethylene production and ACC oxidase activity and, hence, MdFBCP1 may play a role in the ripening process of Fuji apple fruits. Yeast two hybrid and in vitro pull-down assays revealed that MdFBCP1 physically interacted with MdSkp1 and N-terminal F-box motif was essential for this interaction. These results suggest that MdFBCP1 indeed functions as an F-box-containing protein and participates in the formation of SCF complex, which acts as E3 Ub ligase. Genomic Southern blot analysis showed that MdFBCP1 exhibited different pattern of restriction enzyme digestion in three cultivars (Tsugaru, Golden Delicious and Fuji) that produce different amount of ethylene, suggesting that the MdFBCP1 gene is organized in a cultivar specific manner. Collectively, our data suggest that Ub degradation pathway may play an important role in the ripening of Fuji apple fruits.

Expression of MdCAS1 and MdCAS2, encoding apple beta-cyanoalanine synthase homologs, is concomitantly induced during ripening and implicates MdCASs in the possible role of the cyanide detoxification in Fuji apple (Malus domestica Borkh.) fruits.

Fruit ripening involves complex biochemical and physiological changes. Ethylene is an essential hormone for the ripening of climacteric fruits. In the process of ethylene biosynthesis, cyanide (HCN), an extremely toxic compound, is produced as a co-product. Thus, most cyanide produced during fruit ripening should be detoxified rapidly by fruit cells. In higher plants, the key enzyme involved in the detoxification of HCN is beta-cyanoalanine synthase (beta-CAS). As little is known about the molecular function of beta-CAS genes in climacteric fruits, we identified two homologous genes, MdCAS1 and MdCAS2, encoding Fuji apple beta-CAS homologs. The structural features of the predicted polypeptides as well as an in vitro enzyme activity assay with bacterially expressed recombinant proteins indicated that MdCAS1 and MdCAS2 may indeed function as beta-CAS isozymes in apple fruits. RNA gel-blot studies revealed that both MdCAS1 and MdCAS2 mRNAs were coordinately induced during the ripening process of apple fruits in an expression pattern comparable with that of ACC oxidase and ethylene production. The MdCAS genes were also activated effectively by exogenous ethylene treatment and mechanical wounding. Thus, it seems like that, in ripening apple fruits, expression of MdCAS1 and MdCAS2 genes is intimately correlated with a climacteric ethylene production and ACC oxidase activity. In addition, beta-CAS enzyme activity was also enhanced as the fruit ripened, although this increase was not as dramatic as the mRNA induction pattern. Overall, these results suggest that MdCAS may play a role in cyanide detoxification in ripening apple fruits.

Microarray analysis of apple gene expression engaged in early fruit development.

To evaluate gene expressions mostly engaged in early development of apple fruit, we performed the identification of transcripts differentially expressed in young fruit by using microarrays spotted with 6,253 cDNAs collected from young and mature apple fruits of the cultivar Fuji (Malus domestica Borkh. cv. Fuji). A total of 3,484 cDNAs out of 6,253 were selected after quality control of microarray spots and analyzed for differential gene expression patterns between young fruit and other tissues (mature fruit, leaf and flower). Among them, 192 cDNAs displayed a signal value higher than twofold in young fruit compared with other tissues. Blast analysis of the 192 cDNA clones identified 88 non-redundant groups encoding proteins with known function and 50 non-redundant groups with unknown function. The putative protein products were classified into the following categories: photosynthesis (16.7%), protein synthesis (12.3%), cell proliferation and differentiation (10.9%), cell enlargement (5.8%), metabolism (8.0%), stress response (7.2%), others (2.9%), and unknown functions (32.2%). Furthermore, confirming the microarray data by reverse transcription-polymerase chain reaction revealed that the wide range of transcripts differentially expressed in young fruit was expressed in other organs but not in the mature fruit. The data presented suggested that apple fruit development depends on the tight regulation of the expression of a number of genes, which are also expressed in other organs.

Ethylene responsive element binding protein 1 (StEREBP1) from Solanum tuberosum increases tolerance to abiotic stress in transgenic potato plants.

To identify components of the plant stress signal transduction cascade and response mechanisms, we screened plant genes using reverse Northern blot analysis, and chose the ethylene responsive element binding protein 1 (StEREBP1) for further characterization. To investigate its biological function in the potato, we performed Northern blot analysis and observed enhanced levels of transcription in response to several environmental stresses including low temperature. In vivo targeting experiments using a green fluorescent protein (GFP) reporter indicated that StEREBP1 localized to the nucleus of onion epidermal cells. StEREBP1 was found to bind to GCC and DRE/CRT cis-elements and both microarray and RT-PCR analyses indicated that overexpression of StEREBP1 induced expression of several GCC box-containing stress response genes. In addition, overexpression of StEREBP1 enhanced tolerance to cold and salt stress in transgenic potato plants. The results of this study suggest that StEREBP1 is a functional transcription factor that may be involved in abiotic stress responses in plants.

Cloning and characterization of a gene encoding trehalose phosphorylase (TP) from Pleurotus sajor-caju.

Complementary DNA for a gene encoding trehalose phosphorylase (TP) that reversibly catalyzes trehalose synthesis and degradation from alpha-glucose-1-phosphate (alpha-Glc-1-P) and glucose was cloned from Pleurotus sajor-caju. The cDNA of P. sajor-caju TP (designated PsTP, GenBank Accession No. AF149777) encodes a polypeptide of 751 amino acids with a deduced molecular mass of 83.7 kDa. The PsTP gene is expressed in mycelia, pilei, and stipes of fruiting bodies. Trehalose phosphorylase PsTP was purified from PsTP-transformed Escherichia coli. The enzyme catalyzes both the phosphorolysis of trehalose to produce alpha-Glc-1-P and glucose, and the synthesis of trehalose. The apparent K(m) values for trehalose and Pi in phosphorolytic reaction at pH 7.0 were 74.8 and 5.4 mM, respectively. The PsTP gene complemented Saccharomyces cerevisiae Deltatps1, Deltatps2 double-mutant cells, allowing their growth on glucose medium. Furthermore, yeast transformed with PsTP produced 2-2.5-fold more trehalose than non-transformants or cells transformed with empty vector only.