• Restorative Dentistry and Endodontics
• /
• v.35 no.6
• /
• pp.479-485
• /
• 2010

Objectives: The aim of this study was to compare the push-out bond strengths of resin cement/fiber post systems to post space dentin using different application methods of resin cement. Materials and Methods: Thirty extracted human premolars were selected and randomly divided into 3 groups according to the technique used to place the cement into root canal: using lentulo-spiral instrument (group Lentulo), applying the cement onto the post surface (group Direct), and injecting the material using a specific elongation tip (group Elongation tip). After shaping and filling of the root canal, post space was drilled using Rely-X post drill. Rely-X fiber post was seated using Rely-X Unicem and resin cement was light polymerized. The root specimens were embedded in an acrylic resin and the specimens were sectioned perpendicularly to the long axis using a low-speed saw. Three slices per each root containing cross-sections of coronal, middle and apical part of the bonded fiber posts were obtained by sectioning. The push-out bond strength was measured using Universal Testing Machine. Specimens after bond failure were examined using operating microscope to evaluate the failure modes. Results: Push-out bond strengths were statistically influenced by the root regions. Group using the elongation tip showed significantly higher bond strength than other ways. Most failures occurred at the cement/dentin interface or in a mixed mode. Conclusions: The use of an elongation tip seems to reduce the number of imperfections within the selfadhesive cement interface compared to the techniques such as direct applying with the post and lentulospiral technique.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.43 no.4
• /
• pp.273-278
• /
• 1998

Carbohydrate metabolism and partitioning are dependent on relationships between sources and sinks which can be affected by rates of photosynthesis and respiration. Fructan, the major form of stored carbohydrate in tall fescue (festuca arundineacea Schreb.), changes in concentration during growth and in response to the environment. Objectives of this study were i) to examine the content and the composition of carbohydrates in five tissues (mature leaf blade, immature leaf blade, leaf elongation zone, terminal meristem, and root tips) of two tall fescue genotypes, one with high yield per tiller (HYT) and one with low yield per tiller (LYT), and ii) to compare the reserved and utilized carbohydrates among above five different tissues, particularly between the leaf elongation zone and root tips. The established vegetative tillers of the HYT and LYT genotypes were grown in a controlled-environment growth chamber. Water-soluble carbohydrate (WSC) in the leaf elongation zone was about 22% of dry weight in the HYT and about 19% in the LYT genotype. The root tip also had high WSC, about 12% of dry weight in the HYT and 6% in the LYT genotype. Hexoses and sucrose were the major components of total WSC in all tissues except the leaf elongation zone. The growing tissues (sinks), i.e., the leaf elongation zone and root tip, had a high proportion of low degree of polymerization fructan, i.e., 3 to 8 hexose units.

• Journal of Mechanical Science and Technology
• /
• v.17 no.3
• /
• pp.321-328
• /
• 2003

The elongation of contact length on the line of action is considered with particular reference for roll forming of gears, and for dynamic behavior of the tooth in meshing. However there is no paper that discuss the elongation of contact length in the load meshing of gears. Based on our investigation, the contact length on the line of action elongates more than the kinematically calculated value. In rolling, as the tool approaches the workpiece, the center distance of the gears decreases by a small amount. But, the elongation of contact length is sensitive. Therefore, the contact point on the line of action is difficult to be determined, which complicates the tooth analysis. In this study, the exact relation between the elongation of contact length and the tooth space over the recess or before the approach are revealed by experiments and kinematic theory. This analytical result applies not only for rolling, but also for the single flank meshing which is done under constant center distance.

• Journal of Life Science
• /
• v.14 no.3
• /
• pp.396-399
• /
• 2004

This study was investigated the changes of root length, tissue structure of root tip, and dry matter production of a Dongjinbyeo (DJ) cultivar subjected to 0.4 % agar medium with various concentration of NaCl (salt stress)- and polyethylene glycol 6000 (PEG, drought stress). Root length and dry weight of DJ plant were declined along the high concentration of PEG and NaCl in rice plants. To elucidate the changes of tissue structure in root tip to PEG- and NaCl-treatments, we examined the microscopic observation of root tip in NaCl- and PEG-treated rice plants using Toluidine blue O. By Toluidine blue O staining, methyl-lignin accumulation was found in the epidermis and outer cortex of the elongation zone at an early stage of PEG treatment, whereas was found only the outer cortex of the elongation zone of NaCl-treated root tip. The epidermis of NaCl-treated root tip became soften instead of methyl-lignin accumulation. TR ratio was increased along the high concentration in PEG- and NaCl-treated rice plant as a result of inhibited root elongation under PEG- and NaCl-treatment. From these morphological changes in root stimulated by drought and salt stress, we suggest that agar medium is useful to identify tolerant variety in germination stage under stressful environments.

• Journal of Life Science
• /
• v.25 no.11
• /
• pp.1223-1229
• /
• 2015

Oryzalin is a dinitroaniline herbicide, which disrupts the arrangement of microtubules. Microtubules and microfilaments are cytoskeletal components that are thought to play a role in the sedimentation of statoliths and the formation of cell walls. Statoliths regulate the perception of gravity by columella cells in the root tip. To determine the effect of oryzalin on the gravitropic response, ethylene production in primary roots of maize was investigated. Treatment with 10^-4 M oryzalin to the root tip inhibited the growth and gravitropic response of the roots. However, the treatment had no effect on the elongation zone of the roots. An application of 10^-4 M oryzalin for 15 hr to the root tip caused root tip swelling. The application of 1-aminocycopropane-1-carboxylic acid (ACC), a precursor of ethylene, to the root tip also inhibited the gravitropic response. To understand the role of oryzalin in the regulation of the growth and gravitropic response of roots, ethylene production in the primary roots of maize was measured following treatment with oryzalin. Oryzalin stimulated ethylene production via the activation of ACC oxidase (ACO) and ACC synthase (ACS), and it increased the expression of ACO and ACS genes. Indole-3-acetic acid (IAA) played a key role in the asymmetric elongation rates observed during gravitropism. The results suggest that oryzalin alters the gravitropic response of maize roots through modification of the arrangement of microtubules. This might reduce the distribution of IAA in the upper and lower sides of the elongation zone and increase ethylene production, thereby inhibiting growth and gravitropic responses.

• Journal of Korean Society of Forest Science
• /
• v.77 no.4
• /
• pp.445-452
• /
• 1988

This study was conducted to establish practical micropropagation of jujube cultivars ('Geumsumg', 'Bokjo') by axillary bud culture. The results are summerized as follows : 1. Addition of activated charcoal to half-strength Murashige and Skoog(MS) medium supplemented with 0.5mg/l benzylaminopurine(BAP) enhanced shoot and root growth. At 500mg/l activated charcoal level 'Geumsung' showed best result, and shoot length and the number of multiple shoot were 6.4cm and 10.0, respectively. At 1,000mg/l activated charcoal level 'Bokjo showed best result, and shoot length and the number of multiple shoot were 7.5cm and 12.4, respectively. 2. As indole-3-butyric acid(IBA) concentration increased, rooting and callus growth of microshoot were enhanced. The optimum IBA concentration for shoot elongation and multiplication was 1.0mg/l. 3. Growth responses of shoot-tip and axillary bud segments between two jujube cultivars were different. 'Geumsung' showed that axillary bud explants were about twice better than shoot-tip explants for shoot multiplication, but 'Bokjo' showed that shoot-tip explants mere better than axillary bud explants for shoot elongation and multiplication. 4. In acclimatization processes of plantlets produced in vitro, the survival of plantlets with only root primordia in soil medium was better than that of plantlets with several routs resulting in 97.8%. 5. In cutting of in vitro-derived microshoot, paclobutrazol was more effective than IBA, naphth-aleneacetic acid(NAA) and $Rooton^{(R)}$ in rooting and root growth.

• Korean Journal of Plant Tissue Culture
• /
• v.21 no.4
• /
• pp.227-231
• /
• 1994

The experiments were conducted to obtain culture conditions on optimal cultural conditions for propagation of a topical orchid, Haemaria discolor, through shoot tip cultrue in vitro. Survival percentage of shoot tip explant, in initial culture media was higher in H$_3$P$_4$ medium than in Murashige and Skoog's medium. Explants, cultured in H$_3$P$_4$ medium containing 1.0 mg/L kinetin, showed more shoot elongation when compared with those on other media. When the distal part of stem (pseudobulb) was longitudinally sectioned into half and cultured in H3P4 medium containing 0.1 mg/L 2ip, 0.1, or 1.0 mg/L kinetin, shoots from axillary bud were much more elongated under light condition.

• The Korean Journal of Zoology
• /
• v.24 no.2
• /
• pp.65-75
• /
• 1981

The formation of the acrosome during spermatogenesis in Gerris paludum was studied. The Golgi bodies are dispersed randomly in the cytoplasm at the early stage of the spermatocyte and get together to form several group of many bodies, and then they are equally divided into the spermatids by the meiotic divisions. The acroblast first appears in the form of a vesicle and soon an acrosomal granule is differentiated within it. The acroblast is separated from the acrosomal granule at the posterior of the nucleus and is finally sloughed off along the tail filament. The acrosome, after moving to the side of the nucleus opposite the mitochondrial derivatives, differentiates into two zones. The two basal bodies and the differentiated tip originate from the sheath. The basal bodies appear at the proximal part of the sheath simply in contact with the core on one side. During elongation and and narrowing of the acrosomes of the spermatids, they surround the one side at the base of the acrosome and finally all the other are immediately adjacent to the nucleus. The differentiated tip continues to the sheath at the anterior of the cores and is elongated prior to the two basal bodies. They appear to be contiguous twin-tubes, not a single granule in the later stage of the spermatids, and a group of the basal bodies in the sperm bundle.

• Journal of Plant Biotechnology
• /
• v.37 no.4
• /
• pp.517-528
• /
• 2010

Rice seed maturation and germination involve drastic changes in water and nutrient transport, in which tonoplast aquaporins may play an important role. In the present study, gene expression profiles of 10 tonoplast intrinsic proteins (TIP) from rice were investigated by RT-PCR during seed development and germination. OsTIP3;1 and OsTIP3;2 were specifically expressed in mature seeds. Their transcript level rapidly decreased after onset of seed germination and gene expression was induced by ABA treatment. In contrast, expression of OsTIP2;1 and OsTIP4;3 was not seed specific as transcripts were found in vegetative tissues as well. Their respective transcript levels decreased at an early stage of seed development, whereas they increased at a later stage of seed germination and elongation of embryonic roots and shoots. When seed germination was inhibited by various stress conditions and ABA, expression of OsTIP2;1 and OsTIP4;3 was completely suppressed. In contrast, the expression level of OsTIP2;2 rapidly increased after seed imbibition and the transcript level was maintained under conditions inhibiting seed germination. These results implicate that tissue specific and developmental transcriptional regulation of OsTIPs in rice seeds depends on their specific function. In addition, OsTIPs can be discriminated by different potential phosphorylation and methylation sites in their protein structures. OsTIP3;1 and OsTIP3;2 possess unique phosphorylation signatures at their N-terminal domain, loop B and loop E, respectively. OsTIP2;1 and OsTIP4;3 have a potential methylation site at their Nterminal domain. This suggests that activity of specific tonoplast aquaporins may be regulated by post-translational modification as well as by transcriptional control.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.32 no.1
• /
• pp.49-56
• /
• 2010

Objective: To evaluate nasal and upper lip changes after Le Fort I surgery by means of images taken with a three-dimensional computed tomography (3D-CT). Methods: Fifteen patients (9 female and 6 male, mean age 21.9 years) with preoperative and postoperative 3D-CT were studied. The patients underwent maxillary movement with impaction or elongation, and advancement or setback. With the 3D-CT which presents reconstructive soft tissue images, preoperative and postoperative measurement and analysis were performed for nasal tip projection angle, columellar angle, supratip break angle, nasolabial angle, interalar width, internostril width, columella length and nasal tip projection. Results: Postoperative interalar and internostril widening was significant for all categories of maxillary movement. However, there was little significant relation in all parameters between the amount and direction of maxillary movement. Interestingly, movement of the maxilla with upward did show a little decrease in the columellar angle, supra tip break angle and nasolabial angle. Also movement of the maxilla with forward did show a little advancement in the upper lip position. Conclusion: Changes to the nose clearly occur after orthognathic surgery. There was a significant increase in postoperative interalar width and internostril width with maxillary movement. However, no clear correlation could be determined between amount of change and maxillary movement. Interestingly, maxillary impaction did show a little decrease in the columellar angle, supra tip break angle and nasolabial angle. In addition, we used 3D-CT for more precise analysis as a useful tool.