• The Korean Journal of Pesticide Science
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• v.5 no.1
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• pp.36-45
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• 2001

This study was conducted to search new target enzymes of novel herbicide candidate. Total of 107 biochemical inhibitors reported to inhibit over than 100 different plant enzymes were purchased from commercial chemical companies. 15 inhibitors and 34 enzymes were selected by germination assay, seedling assay, wheat leaf disc assay, and whole plant assay. Among them, seven compounds of purine, phehyl-hydrazine, o-phenanthroline, oleylamine, dicyclohexylcarbodiimide, 7,8-benzoquinoline, and aminooxyacetic acid showed high herbicidal activity in the whole plant assay under greenhouse while 7,8-benzoquinone, 8-hydroxyquinoline, 2,2'-dipyridyl, and o-phenanthroline inhibited seed germination of barnyardgrass, rice, and tomato at concentrations of 1.25 to $5{\mu}M$. The compounds of 7,8-benzoquinoline, chlorpromazine, cyanuric fluoride, 4-methylpyrazole, oleylamine, tranylcypromine, and trifluoperazine inhibited the growth of cyanobacteria at 30 to $100{\mu}M$. The compounds of dicyclohexylcarbodiimide and chlorpromazine exhibited whitening effect on tile wheat leaf disc at $100{\mu}M$. These results suggest that the plant-specific enzyme inhibitors which have biological activities may supply the target enzyme for developing new herbicide candidate.

• Clean Technology
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• v.11 no.3
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• pp.129-139
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• 2005

Fluoride-type cleaning agents such as TFEA (2,2,2-trifluoroethanol) and HFE (hydrofluoroether) are noticed to be next generation cleaning agents alternative to CFCs since they do not destruct ozones in the stratosphere due to no containment of chloride in the molecule, have lower global warming potential compared to HFCs and HCFCs, and are thermally stable compounds. Thus, the physical properties and cleaning agents were measured and compared with those of CFC-113, 1,1,1-TCE and HCFC-141b which are ozone destruction substances. They were also compared and evaluated with those of IPA and methanol which are currently employing as alternative cleaning agents. And TFEA-based cleaning agents consisted of TFEA and alcohols or HFEs were formulated, their physical properties and cleaning abilities were measured and their utilization as alternative cleaning agents was evaluated. As a result, TFEA and HFEs have lower cleaning ability for their removal of various soils compared to chloride-type cleaning agents, but theyshow excellent cleaning ability for Fluoride-type soils. And it is observed that the formulated cleaning agents of TFEA and alcohols or HFEs caused to increase cleaning ability of flux and unsoluble cutting oil more than 100% compared to their individual component. Therefore, the fluoride-type cleaning agents are expected to be utilized for development of environmental-friendly non aqueous cleaning agents with excellent cleaning ability if they are formulated with proper solvents or additives.

• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.396-412
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• 1997

The purpose of this study is to observe the corrosion characteristics of five dental amalgams(CAULK FINE CUT, OPTALLOY II, DISPERSALLOY, TYTIN, and VALIANT) in the solutions with fluoride compound through the anodic polarization curve obtained by using a potentiostat. After each amalgam alloy and Hg being triturated, the triturated mass was inserted into the cylindrical metal mold, and condensed by hydraulic pressure(160 kg/$cm^2$). Each specimen was removed from the metal mold. Specimens were polished with the silicone carbide grinding paper 24 hours after condensation and stored at room temperature for 1 week. The anodic polarization curves were employed to compare the corrosion behaviours of the amalgams in 0.9 % saline solution and in the saline solutions with 2.2 ppm, 0.05 %, 2 % NaF, and 8 % $SnF_2$ at $37^{\circ}C$ with 3-electrode potentiostat. After the immersion of specimen in electrolyte for 30 minutes, the potential scan was begun. The potential scan range was -1500m V to + 800m V(vs. S.C.E.) in the working electrode and the scan rate was 50 mV/sec. The results were as follows, 1. The corrosion potential, the potential of anodic current peak, and transpassive potential in the saline solutions with NaF shifted to lower direction than those in normal saline solution, and the current density in the saline solutions with NaF was higher than that in normal saline solution. The differences were increased as the concentrations of NaF became higher. 2. The corrosion potential and transpassive potential in the saline solution with $SnF_2$ shifted to higher direction than those in normal saline solution, and the current density in the saline solution with $SnF_2$ was higher than that in normal saline solution after the corrosion potential. The anodic polarization curves in the saline solution with $SnF_2$ had no outstanding anodic current peak. 3. The corrosion potentials for high-copper amalgams were much higher than those for CAULK FINE CUT and OPTALLOY II in normal saline solution, but, as the concentrations of fluoride compound became higher, the differences in corrosion potentials between them were decreased. The corrosion potentials had the similarity in the saline solution with 2% NaF or 8% $SnF_2$. 4. The current density for TYTIN was the lowest among the others in normal saline solution and in the saline solution with 2.2 ppm or 0.05 % NaF. 5. There was no significant difference in current density between Pd-enriched VALIANT and other high-copper amalgams.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.3
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• pp.306-315
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• 2012

In this study, storage stability of reduced sulfur compounds ($H_2S$, $CH_3SH$, DMS, $CS_2$, and DMDS) and $SO_2$ in sampling bags was investigated in terms of two contrasting storage approaches between forward (F) and reverse (R) direction. The samples for the F method were prepared at the same time and analyzed sequentially through time. In contrast, those of reverse (R) method were prepared sequentially in advance and analyzed all at once upon the preparation of the last sample. In addition, relative performance between two different bag materials (PVF and PEA) was also assessed by using 100 ppb standard. The response factors (RF) of gaseous RSC samples were determined by gas chromatography/pulsed flame photometric detector (GC/PFPD) combined with air server (AS)/thermal desorber (TD) system at storage intervals of 0, 1, and 3 days. There is no statistical difference in all RSCs between two storage methods. However, the results of relative recovery indicated 2.58~12.8% differences in compound type between the two storage methods. Moreover, loss rates and storage stability of $H_2S$ and $SO_2$ were considerably affected by bag materials than any other variables. Therefore, some considerations about storage methods (or bag material types) for sulfur compounds are needed if stored by sampling bag method.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.8 no.2
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• pp.63-70
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• 2022

The development of myocardial perfusion imaging (MPI) agents has been motivated because coronary artery disease has been one of the leading causes of death worldwide since the 1960s. Several positron emission tomography (PET) MPI agents were developed, and ¹⁸F-labeled phosphonium cations were reported actively among them. In this study, we synthesized novel ¹⁸F-labeled phosphonium cations, (5-[¹⁸F]fluoropentyl)diphenyl(pyridin-2-yl)phosphonium and (2-(2-[¹⁸F]fluoroethoxy)ethyl)diphenyl(pyridin-2-yl)phosphonium, and evaluated potential as MPI agents. Two labeled compounds were synthesized via nucleophilic substitution reactions of ¹⁸F-fluoride with the appropriate tosylate precursor in the presence of Kryptofix 2.2.2 and K₂CO₃. MicroPET studies were performed in normal rats to evaluate in vivo distribution of radiolabeled phosphonium cations for 60 min. The radiolabeled compounds were synthesized with 5%-10% yield. The radiochemical purity of labeled compounds was > 98% by analytical HPLC, and the specific activity was > 11.8 GBq/µmol. The result of microPET studies of these labeled compounds in rats showed intense uptake in the myocardium at 30 and 60 min. The results suggest that these ¹⁸F-labeled novel phosphonium cations would have potential as promising candidates for myocardial perfusion imaging.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.349-350
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• 2002

The friction and wear behaviors of fluorine-containing compounds such as perfluoropolyethers (PFPE), phosphazenes (X-1P), ionic liquids as lubricants for steel/seel, steel/ceramic, ceramic/ceramic were investigated using a SRV tester and a one-way reciprocating friction tester both in ball-on-disc configuration. It was found that the three fluorine-containing lubricants could reduce friction coefficient and wear volume effectively. The effectiveness of the three lubricants in reducing wear volume could be ranked as ionic liquids>X-1P>PFPE. Tests also showed that aryloxyphosphazene with polar substituent as a lubricant of steel/steel pair gave low wear, while aryloxyphosphazene with nonpolar group on the phenyl pendant led to high wear. The morphology and the tribo-chemical reaction of the worn surfaces were analyzed with a scanning electron microscope (SEM) and X-ray photoelectron spectroscope (XPS). XPS analyses illustrated the formation of iron fluoride in steel/steel system with the lubrication of both phosphazenes and ionic liquids.

• Microbiology and Biotechnology Letters
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• v.23 no.1
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• pp.53-59
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• 1995

A protease isolated and purified 51 fold from the culture filtrate of a soil bacterium, Bacillus sp. KUN-17, which was appeared to be a monomeric protein with molecular weight of 38, 000 daltons, was suggested to be involved in the serine (-alkaline) protease (E.C 3.4.21.14) since its activity was selectively inhibited by phenylmethylsulfonyl fluoride (PMSF) and required 40$\circ$C and pH 10.5 for optimal condition. The half-life of the enzyme activity was 1 hr at 55$\circ$C, and the activity was maintained even under high concentrations of SDS or urea. The enzyme was indicated to perform random proteolysis from the fact that most of the chromogenic substrates employed were hydrolyzed by the enzyme. The affinity of the enzyme for natural proteins was approximately 10-times higher than ester compounds, and both substrates showed mutual inhibitory effect competitively for the enzyme activity.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.284-284
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• 2006

Electrospray deposited films of poly(vinylidene fluoride) were prepared with various conditions. A model has been developed, which provides the state of the electrosprayed droplet at impact. With a combination of the experimental films and the model calculations, it can be shown that growth rate, the increase of the sprayed solution on the substrate per second, defines the film morphology in electrospray deposition. Growth rate indicates which factors play the main role in the film formation process. The most important factors are liquid flow, surface tension and shear rate. The model can calculate the shear rate and it is shown that PVDF, and most likely polymers in general, has a large range of growth rates, where the morphology only depends on the shear rate of the depositing droplet. This method can also be used to describe electrospray deposition of other compounds.

• Archives of Pharmacal Research
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• v.22 no.6
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• pp.575-578
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• 1999

Derivatives of elema-1,3-diene were synthesized in several steps as polar analogs of $\beta$-elemene, antitumor agent under clinical phase. The lactone ring of compound 1 was opened by LiAlH4 to give diol 2 which was selectively protected by TBDPSCI. After acetylation of the secondary alcohol, the acetylated product was ozonolyzed and reduced to give elemene derivative 4 which was converted to diolefin 8 via selenides subsequent deprotection by tetrabutylammonium fluoride gave two compounds 9, 10.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.2 no.1
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• pp.51-55
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• 2016

Organofluorine compounds have become increasingly important as pharmaceuticals, radiopharmaceuticals, agrochemicals, and material science. Recent advances on the efficient introduction of fluorine to organic molecules are mainly results of development of transition metal catalysts and fluorination reagents. Among the various fluorination reagents, we have been interested in developing more efficient sulfur-based deoxyfluorinating reagents. Here we report various electronic properties of five popular sulfur-based deoxyfluorinating reagents using density functional theory calculation. We believe that the theoretical study on the reagents will assist the rational design of new deoxyfluorinating reagents.