• 대한치과보철학회지
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• 제35권3호
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• pp.504-516
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• 1997

Ultrasonic instruments transfer electrical energy to mechanical energy resulting in vibration used for various dental treatments. If we could know the effect of ultrasonic instruments on the dental cements within the cast crown, we could take care when conducting periodontal surgery and when using the ultrasonic instrument to remove cast crown, it would be much more convenient. The purpose of this study was to compare the bond strength of several dental cements according to ultrasonic instrumentation time. In this study 4 types of cements were used to cement the specimens. they were treated with ultrasonic instrumentation for 0-5 minutes and the change in bond strength were statistically compared. The results were as followed. 1. The tensile bond strength of zinc phosphate cement decreased according to the increase in time of ultrasonic instrument and showed significant difference between 0 minutes and the others and between 1 minute and 2,3,4,5 minutes (p<0.05). 2. The tensile bond strength of polycarboxylate cement decreased according to the increase in time of ultrasonic instrument and showed significant difference between 5 minutes and the others and between 4 minutes and 0 minutes (p<0.05). 3. The tensile bond strength of zinc phosphate cement decreased according to the increase in time of ultrasonic instrument and showed significant difference between 5 minutes and the others (p<0.05). 4. The tensile strength of resin cements showed no statistically differences according to the ultrasonic instrumentation time. In conclusion, it is considered that zinc phosphate cements is most affected by ultrasonic instrumentations and resin cement is the least affected. When using ultrasonic instruments the result avove should be used as an index.

• 대한소아치과학회지
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• 제26권3호
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• pp.528-537
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• 1999

Stainless steel crown은 소아치과 영역에서 가장 효과적이면서 신뢰할 수 있는 수복방법으로 그 사용이 확대되는 추세이다. 선학들의 연구에 의하면, stainless steel crown의 장착에 있어서 시멘트를 사용한 경우가 사용하지 않은 경우보다 8배 이상의 유지력을 얻을 수 있으므로, stainless steel crown 시술에 있어서 시멘트는 중요한 부분이라고 할 수 있다. 본 연구는 stainless steel crown의 접착을 위하여 임상적으로 흔히 사용되는 인산아연 시멘트, 폴리카복실레이트 시멘트, 접착용 글래스 아이오노머 시멘트의 접착력을 비교분석 할 목적으로 시도되었다. 인산아연 시멘트로 FLECK'S, 폴리카복실레이트 시멘트로는 HY-Bond, 접착용 글래스 아이오노머 시멘트로는 Vitremer, stainless steel로는 Sun-Platinum plate를 사용하였다. Bovine teeth, 글래스 아이오노머 시멘트(Fuji II LC), 아말감(Valiant)상에 3종의 시멘트로 형성된 기둥을 세워 양자간의 접착력을 측정하였고, 한편으로는 stainless steel plate 상에 3종의 시멘트 기둥을 세워 또한 양자간의 인장접착 강도를 만능시험기로 측정하였다. 측정치를 ANOVA와 Student t-test로 통계 처리하여 다음과 같은 결과를 얻었다. 1. Stainless steel crown에 대해 글래스 아이오노머 시멘트와 폴리카복실레이트 시멘트가 인산아연 시멘트보다 높은 인장결합강도를 보였고, 글래스 아이오노머 시멘트와 폴리카복실레이트 시멘트 사이에는 차이가 없었다. 2. Bovine teeth와 수복용 글래스 아이오노머 시멘트에 대해서는, 접착용 글래스 아이오노머 시멘트가 가장 높은 인장결합강도를 보였고, 다음으로 폴리카복실레이트 시멘트와 인산아연 시멘트의 순이었다. 3. 아말감 수복재에 대해서는, 폴리카복실레이트 시멘트와 글래스 아이오노머 시멘트가 인산아연 시멘트보다 높은 인장결합강도를 보였고, 폴리카복실레이트 시멘트와 글래스 아이오노머 시멘트 사이에는 유의한 차이가 없었다.

• 대한치과보철학회지
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• 제38권2호
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• pp.169-177
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• 2000

The purpose of this study was to compare the retention of complete cast crown over amalgam ores, composite resin cores, and cast gold cores when cemented with three different luting agents. Eighteen core specimens each of amalgam(Bestaloy, Dong Myung, Seoul, Korea), composite resin (Z100, 3M Dental product, st. Paul, Minn) and type IV gold alloy (Ba-4, Heesung Engelhard Corp., Korea) were made in a customized milling stainless steel die. A wax pattern with a loop attached to occlusal surface was made for each core and a type II gold alloy casting was fabricated. The castings which had clinically acceptable marginal fit were used as test samples. The following luting cements were used to cement cast crowns on each core material : (1) zinc phosphate cement (Confi-dental Products Co., USA) (2) glass-ionomer cement (Fuji Plus, GC Industrial Corp., Tokyo, Japan) (3) resin cement (Panavia 21, Kuraray Co., USA). All cements were mixed according to manufacturers' instructions. A static load of 5kg was then applied for 10 minutes on the crowns. All specimens were stored in saline solution for 24 hours at $37^{\circ}C$ and thermocycled for 500 cycles. After storage and cycling, the tensile bond strengths were measured by using a universal testing machine (Instron Corp., Canton, Mass.) at a crosshead speed of 0.5mm/min. The results were as follows 1. The retentive strength of resin cement was the highest of alt three types of cement for resin core (p<0.05). 2. There was no statistical difference among the retentive strengths of three cements for amalgam core (p>0.05). 3. The retentive strength of resin cement was higher than that of zinc phosphate for cast core, but there was no difference between the retentive strength of glass ionomer cement and those of rein and zinc phosphate cement. 4. The retentive strength of the zinc phosphate cement for amalgam core was the highest of all type of cores.

• Imaging Science in Dentistry
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• 제53권2호
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• pp.127-135
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• 2023

Purpose: This study assessed the intensity of artifacts produced by 2 metal posts, 2 cements, and different exposure parameters using 2 cone-beam computed tomography (CBCT) units. Materials and Methods: The sample was composed of 20 single-rooted premolars, divided into 4 groups: Ni-Cr/zinc phosphate, Ni-Cr/resin cement, Ag-Pd/zinc phosphate, and Ag-Pd/resin cement. Samples were scanned before and after post insertion and cementation using a CS9000 3D scanner with 4 exposure parameters (85/90 kV and 6.3/10 mA) and an i-CAT scanner with 120 kV and 5 mA. The presence of artifacts was assessed subjectively by 2 observers and objectively by a trained observer using ImageJ software. The Mann-Whitney, Wilcoxon, weighted kappa, and chi-square tests were used to assess data at a 95% confidence level(α<0.05). Results: In the subjective analyses, AgPd presented more hypodense and hyperdense lines than NiCr (P<0.05), and more hypodense halos were found using i-CAT (P<0.05) than using CS9000 3D. More hypodense halos, hypodense lines, and hyperdense lines were observed at 10 mA than at 6.3 mA (P<0.05). More hypodense halos were observed at 85 kV than at 90 kV (P<0.05). CS9000 3D presented more hypodense and hyperdense lines than i-CAT (P<0.05). In the objective analyses, AgPd presented higher percentages of hyperdense and hypodense artifacts than NiCr (P<0.05). Zinc phosphate cement presented higher hyperdense artifact percentages on CS9000 3D scans(P<0.05). CS9000 3D presented higher artifact percentages than i-CAT(P<0.05). Conclusion: High-atomic-number alloys, higher tube current, and lower tube voltage may increase the artifacts present in CBCT images.

• 청정기술
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• 제19권3호
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• pp.257-263
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• 2013

인산아연이 도포된 운모 안료(ZP/mica)를 인산, 질산아연 그리고 운모를 출발물질로 하여 제조한 후, 방청안료로 사용하였다. 주사전자현미경 및 X-선 회절분석기 등을 이용하여 제조된 안료의 형상과 결정구조를 관찰하였다. 제조된 안료와 에폭시수지를 배합하여 도막을 형성시킨 다음 전기화학적 임피던스법을 이용하여 안료의 방청성을 평가하였다. $70^{\circ}C$에서 합성된 ZP/mica 안료의 방청성이 $20^{\circ}C$에서 제조된 안료보다는 우수하다는 것을 알 수 있었다. $70^{\circ}C$에서 합성된 ZP/mica 안료표면에는 $Zn_3(PO_4)_2{\cdot}2H_2O$ 이외에도 ZnO가 동시에 생성되어 있음을 볼 수 있었다. 합성된 ZP/mica 안료의 우수한 방청성은 운모표면의 아연화합물에 의한 전기화학적 방청기구와 판상구조의 운모에 의한 장벽 방청기구의 상승작용에 기인한 것으로 생각된다.

• Molecules and Cells
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• 제40권10호
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• pp.697-705
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• 2017

The maintenance of inorganic phosphate (Pi) homeostasis is essential for plant growth and yield. Plants have evolved strategies to cope with Pi starvation at the transcriptional, post-transcriptional, and post-translational levels, which maximizes its availability. Many transcription factors, miRNAs, and transporters participate in the Pi starvation signaling pathway where their activities are modulated by sugar and phytohormone signaling. Environmental stresses significantly affect the uptake and utilization of nutrients by plants, but their effects on the Pi starvation response remain unclear. Recently, we reported that Pi starvation signaling is affected by abiotic stresses such as salt, abscisic acid, and drought. In this review, we identified transcription factors, such as MYB, WRKY, and zinc finger transcription factors with functions in Pi starvation and other environmental stress signaling. In silico analysis of the promoter regions of Pi starvation-responsive genes, including phosphate transporters, microRNAs, and phosphate starvation-induced genes, suggest that their expression may be regulated by other environmental stresses, such as hormones, drought, cold, heat, and pathogens as well as by Pi starvation. Thus, we suggest the possibility of cross-talk between Pi starvation signaling and other environmental stress signaling pathways.

• Asian-Australasian Journal of Animal Sciences
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• 제17권10호
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• pp.1378-1382
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• 2004

Zinc (Zn) is a micromineral and functions as a cofactor of many enzymes and its deficiency induces retardation of growth and dysfunction of the immune system in animals. This study was conducted to determine lipogenic activity of Zn in bovine intramuscular adipocytes. Preadipocytes were isolated from intramuscular fat depots of 26 month old Korean (Hanwoo) steers and cultured in media containing Zn. At confluence, the cells were treated with insulin, dexamethasone, and 1-methyl-3-isobutyl-xanthine to induce differentiation (accumulation of lipid droplets in cells). The sources of Zn were zinc chloride (${ZnCl}_2$) and zinc sulfate (${ZnSO}_4$), and the final concentrations of both Zn sources were 0, 5, 25, 50 and 100 ${\mu}$M. Glycerol-3-phosphate dehydrogenase (GPDH) activity, an index of adipocyte differentiation, was increased as the concentration of Zn in media increased showing the highest activity (25.74 ng/min/mg protein) at 25 ${\mu}$M of ${ZnSO}_4$. Supplementation of Zn during differentiation of bovine intramuscular adipocytes tended to decrease the production of nitric oxide (NO). Peroxisome proliferator-activated receptor gamma 2(PPAR$\gamma$2) gene expression was increased 10 days after differentiation induction. The current results indicate that Zn has a strong lipogenic activity in cultured bovine intramuscular adipocytes with remarkable suppression of NO production.

• Korean Chemical Engineering Research
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• 제55권6호
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• pp.785-790
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• 2017

To collect zinc, Fe and Zn in spent pickling solution were extracted by using TBP (tributyl phosphate), and Zn was recovered from extracted solution to zinc oxalate particles by oxalic acid solution. The reusability of TBP solvent was also tested. The distribution coefficient of Zn was not affected by the concentration of Fe in spent pickling solution, almost constant with the values of 7.12~9.31 when extracted by TBP solvent. It was found that the extraction capacity of TBP solvent for Zn is higher than that for Fe. The extraction efficiency of Zn was higher than 95%, while most of Fe was left in aqueous phase. After the recovery, the used TBP solvent could be repeatedly reused for the extraction of Zn up to eight times. XRD analysis showed that zinc oxalate ($ZnC_2O_4$ $2H_2O$) was formed from the reaction of Zn-TBP and oxalic acid. From the results of SEM analysis, the formation of zinc oxalate particle was strongly affected by the concentration of oxalic acid. In summary, Zn in spent pickling solution was successfully separated and recovered with TBP solvent and oxalic acid solution, respectively.

• Journal of Microbiology and Biotechnology
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• 제32권11호
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• pp.1435-1446
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• 2022

Zinc-solubilizing bacteria can convert the insoluble form of zinc into soluble forms available to plants. This study was conducted to isolate and screen zinc-solubilizing actinobacteria from rhizosphere soils and to assess their effect on vegetable soybean growth. In total, 200 actinobacteria strains belonging to 10 genera were isolated from rhizosphere soil samples. Among these isolates, four showed zinc solubilization with solubilizing index values ranging from 3.11 to 3.78 on Bunt and Rovira agar supplemented with 0.1% zinc oxide. For the quantitative assay, in broth culture, strains CME34 and EX51 solubilized maximum available zinc contents of 529.71 and 243.58 ㎍/ml. Furthermore, indole-3-acetic acid (IAA) and ammonia were produced by these two strains, the strain CME34 produced the highest amount of IAA 4.62 ㎍/ml and the strain EX51 produced the highest amount of ammonia 361.04 ㎍/ml. In addition, the phosphate-solubilizing abilities in Pikovskaya's medium of CME34 and EX51 were 64.67 and 115.67 ㎍/ml. Based on morphological and biochemical characterization and 16S rDNA sequencing, the strains CME34 and EX51 were closely related to the genus Streptomyces. In a greenhouse experiment, single-strain inoculation of Streptomyces sp. CME34 or EX51 significantly increased the shoot length, root length, plant dry weight, number of pods per plant and number of seeds per plant of vegetable soybean plants compared to the uninoculated control. These findings facilitated the conclusion that the two Streptomyces strains have potential as zinc solubilizers and can be suggested as bioinoculants to promote the growth and yield of soybean.