Kiho Kim

Analysis of transcripts expressed from the UL47 gene of human cytomegalovirus

The UL47 gene (b 60390-b 60338) located in the unique long region of the human cytomegalovirus (HCMV) AD169 strain genome was analyzed by RNA mapping. Northern blot analysis showed that the UL47 gene was expressed at late times after infection (72 h postinfection). The 9.7-kb transcript was expressed in the infected cells but not in phosphonoformate-treated cells at 72 hpi, indicating that the UL47 gene was only expressed at late times after infection. To map the 5′-end and 3′-end of UL47 transcripts, primer extension and RNase protection analysis were performed. Primer extension analysis revealed that the transcription initiation site of UL47 was located in 27 bp downstream (b 60323) of the TATA box motif. The sizes of UL47 ORF (approximately 2.9-kb) and UL48 ORF (approximately 6.7-kb) deduced from computer sequence analysis suggest that the expressed 9.7-kb transcript of UL47 uses the 3′-end polyadenylation signal of UL48. The result of RNase protection determined that the 3′-end of UL47 RNA utilized the 3′-end polyadenylation signal of UL48, which is located in HCMV genome b 70082.

Applications Using the Metal Affinity of Polyphenols with Mussel-Inspired Chemistry

Multi-functionality plays a decisive role in tuning and improving fundamental properties of active molecules, and grafting polymerization/conjugation development imparts properties of active molecules to the backbones. Recently, metal-polyphenol coordination networks have attracted a great deal of attention. A variety of transition metal ions can freely combine with catechol/keto-enol containing polyphenols to form metal-polyphenol networks. Herein, the recently studied conjugated polyphenols were summarized and compared to dopamine-conjugated polymers with evaluation of their properties and gelation behaviors. The biomimetic understanding of bioinspired adhesion, metal ion coordination of hydroxyl groups, and their rearrangement within aglycone could expand the ability for the development of biomimetic, eco-friendly, and biocompatible polymers.

Influence of functionalized graphene on the electrical, mechanical, and thermal properties of solderable isotropic conductive adhesives

Graphene nanosheets have attracted considerable attention as ideal reinforcing filler materials for polymer composites due to their superior physical properties. In this paper, to investigate the influence of functionalized graphene on the electrical, mechanical, and thermal properties of solderable isotropic conductive adhesives (SICAs) with low-melting-point alloy, three types of SICAs [without and with graphene oxide (GO) and amine-modified GO (GO-NH2)] were prepared. All SICA assemblies without and with different functionalized graphene sheets showed excellent electrical and mechanical properties due to the formation of uniform and stable metallurgical conduction paths. The epoxy composite with GO sheets showed superior thermal conductivity to the epoxy composite with GO-NH2 sheets. Our results demonstrated that graphene sheets within SICAs do not affect the electrical and mechanical properties of SICA joints, and that GO sheets are more suitable for enhancing the thermal conductivities of polymer composites than GO-NH2 sheets.

Time Course of Visual Attention to High-Calorie Virtual Food in Individuals with Bulimic Tendencies

The aim of the present study was to use an eye-tracking device to investigate attention bias and its mechanism toward high-calorie virtual food in individuals with bulimic tendencies (BT). A total of 76 participants were divided into two groups: a BT group (n = 38) and a control group (n = 38). The eye movements of all participants were continuously measured while the participants were confronted with pairs of high-calorie, low-calorie, and nonfood virtual stimuli (pictures). It was found that the BT group detected high-calorie food more quickly than they did the low-calorie food and nonfood stimuli, but they also avoided the high-calorie food. These results indicate that individuals with BT automatically allocate their attention toward high-calorie food and, subsequently, try to avoid it. Based on these results, we suggest that this approach-avoidance pattern for high-calorie virtual food could be a factor in the development and maintenance of bulimia symptoms by encouraging individuals with BT to be in conflict with the urge to overeat.

The Influence of Arousal and Expectation on Eyewitness Memory in a Virtual Environment

This study aimed to examine the effects of arousal and expectation on eyewitness memory. We exposed 97 participants to an immersive eyewitness experience by creating four virtual reality stimulus environments. The participants were randomly assigned to one of four conditions: arousing and expected, arousing and unexpected, nonarousing and expected, and nonarousing and unexpected. The results revealed that memory performance for an arousing encounter was significantly lower than that for a nonarousing encounter, and that memory performance for an unexpected environment was significantly lower compared with an expected one. In addition, memory performance was lowest in the condition that was both arousing and unexpected. No interaction between arousal and expectation was found.

The influence of attention toward facial expressions on size perception

According to the New Look theory, size perception is affected by emotional factors. Although previous studies have attempted to explain the effects of both emotion and motivation on size perception, they have failed to identify the underlying mechanisms. This study aimed to investigate the underlying mechanisms of size perception by applying attention toward facial expressions using the Ebbinghaus illusion as a measurement tool. The participants, female university students, were asked to judge the size of a target stimulus relative to the size of facial expressions (i.e., happy, angry, and neutral) surrounding the target. The results revealed that the participants perceived angry and neutral faces to be larger than happy faces. This finding indicates that individuals pay closer attention to neutral and angry faces than happy ones. These results suggest that the mechanisms underlying size perception involve cognitive processes that focus attention toward relevant stimuli and block out irrelevant stimuli.

Evaluation of tTA-mediated gene activation system on human cytomegalovirus and herpes simplex virus type-1 infections

The tetracycline-controlled transactivator (tTA)-mediated gene activation system was examined in virus infected cells to determine its role in the control of gene expression. In the presence of tTA, the gene expression from thetetO-modified minimal promoter was efficiently activated in the uninfected cells, whereas essentially no activation was observed from the only minimal promoter without the seven direct repeats of 42 bptetO sequences. However, essentially no activation was observed when only the minimal promoter was used, without the seven direct repetitions of the 42 bptetO sequences. On the other hand, in the infected cells, a substantial background of β-glucuronidase expression was detected in the absence of tTA, even though tTA stimulated the gene expression by ∼7-fold. This background expression indicates that the sequences within or nearbytetO are involved in the background stimulation of the gene expression by HCMV and HSV-1. These results suggest that the application of the tTA-mediated gene activation system may not be extremely useful for studying the biological roles of HCMV and HSV genes in the viral replicative cycles, because of the basal activity of the gene expression.

Comparison between of the attenuated BR-Oka and the wild type strain of Varicella Zoster Virus (VZV) on the DNA level.

Oka strain VR-795 (Varicella Zoster Virus, VZV) of American Type Culture Collection (ATCC) has been used for chickenpox vaccine production. In order to use this strain for vaccine production, the strain must be identified and its stability must be confirmed. The identification of the Oka strain has been confirmed using Restriction Fragment Length Polymorphism (RFLP) and DNA sequence analysis of glycoprotein-II (gp-II). The amino acid sequences of Oka deduced from the DNA sequence of gp-II have changed at three amino acids against Ellen and at one amino acid against Webster. To prove the stability of the Oka strain during the passage, RFLP and DNA sequence analyses were also used with 11, 15 and 23 times of virus passage. We found that the Oka strain was stable at passages of up to 23 times, based on the RFLP and DNA sequence analyses. The confirmed Oka strain was renamed as BR-Oka for the purposes of chickenpox vaccine production.

Fabrication of covalently linked exfoliated boron nitride nanosheet/multi-walled carbon nanotube hybrid particles for thermal conductive composite materials

Boron nitride nanosheet (BNNS)/multi-walled carbon nanotube (MWCNT) hybrid particles were synthesized for use as a conductive filler for epoxy and polyphenylene sulfide (PPS). BNNSs were prepared via the exfoliation of bulk boron nitride (BN) particles. Micrometer-sized BN particles were exfoliated to form nanosheets, and their surfaces were modified using 3-aminopropyltriethoxysilane (APTES). The amine groups on the BNNS surface were reacted with acid-treated MWCNTs, and covalently connected BNNS/MWCNT particles were synthesized. Moreover, a chemical reaction without agitation increased the particle connection during the hybrid particle preparation, resulting in a large number of MWCNTs being introduced onto the BNNSs. The BNNS/MWCNT hybrid particle composite had better thermal conductivity than BNNSs or a BNNS/MWCNT composite without chemical bonding based on the same filler contents and composition. This was because of the particle connections establishing three-dimensional heat conducting path in a matrix, which affected the thermal conductivity of the composite.

Laser direct structuring and electroless plating applicable super-engineering plastic PPS based thermal conductive composite with particle surface modification

Boron nitride (BN) and laser activate particles (LAPs) were surface-modified via base treatment and by using a silane coupling agent in order to confer functionality and enhance the interfacial affinity of these particles for a polymer matrix. The introduction of LAP and BN caused severe deterioration of the mechanical properties of the filler–polymer composite by acting as defects and due to the poor interface with polyphenylene sulfide (PPS), used as the polymeric matrix. As expected, the thermal and mechanical properties were enhanced via surface modification, whereas the tensile strength of the composites with the surface-modified fillers remained lower than that of neat PPS. The BN/LAP binary filler system showed little influence on the mechanical properties of the composite. However, the incorporation of a small amount of LAP into the BN composite produced a slight improvement of the thermal conductivity when the total filler content was maintained. Moreover, LAP leads the metal plating at the laser irradiated surface. Thus, the BN/LAP/PPS composite was used to fabricate a circuit board via laser direct structuring (LDS) and electroless plating for potential light emitting diode (LED) application.