• Proceedings of the Membrane Society of Korea Conference
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• 1995.10a
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• pp.45-46
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• 1995

Generally, two different techniques have been employed for the precipitation of membranes from a polymer casting solution. In the first method, a precipitant is introduced from a vapor phase. In this case the precipitaion rate is very slow and a more or less symmetric structure is formed. In the second method, a precipitant is added to a casting solution by immersing the cast polymer film in a nonsolvent bath. In this case the precipitation rate is very fast and a skinned asymmetric membrane structure is obtained. In this study, we introduced water-vapor to PSf/NMP solution and took photographs of phase separation phenomena of polymer lean phase.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.202.3-202.3
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• 2003

Two Known compounds, syringaresinol monoglucoside(8), chimaphilin(14), together with three new compounds, (9)[mp. $106{\sim} 111^{\circ}C$, C_{29}H_{44}O_{13}$], (10)[mp. $180{\sim}182^{\circ}C$, $C_{15}H_{20}O_{9}$] and (11)[mp. $100{\sim}105^{\circ}C$, $C_{18}H_{28}O_{8}$] were isolated from the BuOH fractionof Pyrola japonics(Pyrolaceae). The structures of the known compounds were determined by chemical and spectorscopic methods. The assignments of the $^{1}H-$ and $^{13}C-NMP$ spectra of these compounds were carried out by two-dimensional $^1H-^1H-COSY$, NOESY and $^1H-^{13}C$ multiple-bond, multiplequantum spectroscopic correlation techniques. The characterization of the three new compounds is now in progress.

• The Korean Journal of Cytopathology
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• v.17 no.1
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• pp.18-26
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• 2006

Transitional cell carcinoma of the urinary bladder is common in the genitourinary tract. The gold standard for the diagnosis of bladder cancer has been cystoscopy, along with urine cytology. Cystoscopy is an invasive and relatively expensive technique. By comparison, urine cytology is easy to perform and specific for a diagnosis of bladder cancer, although less sensitive, especially in low-grade tumors. For this reason, there has been a need for superior noninvasive technology to increase our confidence in being able to detect bladder cancer. There are many reports of the various urinary tests that are available to facilitate the diagnosis. In this article, I reviewed the literature on urinary markers and tests that may be clinically useful, including fluorescence in situ hybridization, uCyt+/Immunocyte, the $BTA^{(R)}$ test, the NMP 22TM, the $FDP^{(R)}$ test, the telomerase activity test, the HA and HAse tests, and flow cytometry. Most of these tests have a higher sensitivity and specificity than cytology. However, urine cytology has the highest specificity, especially in individuals with a high-grade tumor. We conclude that no urinary markers or tests can replace the role of cystoscopy along with cytology in the diagnosis of transitional cell carcinoma of the bladder. However, some markers could be used adjunctively to increase the diagnostic accuracy during screening or during the postoperative follow-up examination of patients with bladder cancer.

• Macromolecular Research
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• v.17 no.11
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• pp.912-918
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• 2009

An optically active diacid containing the L-histidine moiety was prepared by reacting pyromellitic dianhydride (1,2,4,5-benzenetetracarboxylic acid 1,2,4,5-dianhydride) 1 with L-histidine 2 in acetic acid, and was polymerized with several aromatic diamines 5a-g to obtain a new series of optically active poly(amide-imide)s (PAIs) using two different methods, such as direct polycondensation in a medium consisting of N-methyl-2-pyrrolidone (NMP)/triphenyl phosphite (TPP)/calcium chloride ($CaCl_2$)/pyridine (Py) and direct polycondensation in a tosyl chloride (TsCl)/pyridine (Py)/N,N-dimethylformamide (DMF) system as a condensation agent. The resulting new polymers 6a-g with inherent viscosity was obtained in good yield. The polymers were readily soluble in polar organic solvents, such as N,N-dimethyacetamide (DMAc), N,N-dimethyformamide (DMF), and dimethyl sulfoxide (DMSO). The obtained polymers were characterized by FTIR, specific rotation, elemental analysis as well as $^1$H-NMR spectroscopy and gel permeation chromatography (GPC). The thermal stability of the resulting PAIs was evaluated with thermogravimetric analysis techniques under a nitrogen atmosphere.

• Analytical Science and Technology
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• v.36 no.2
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• pp.99-104
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• 2023

Trace elements (TEs) have significant effects on both dental health and human health. Toxic effects are caused by deficiency or excess of TEs. This study was performed to determine levels of toxic and trace elements in incisor and molar teeth sampled from male and female participants residing in the north and south regions of Sudan. The tooth enamel of 18 extracted human teeth was analyzed using particle-induced x-ray emission (µ-PIXE) to determine its elemental profile and distribution. GeoPIXEII software package was used for the analysis of µ-PIXE data. The main elements determined were Na, Mg, P, S, Cl, K, Ca, Mn, Fe, Zn, Co, and Sr which were homogeneously distributed in the areas of the tooth enamel mapped with micro-PIXE.

• Advances in nano research
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• v.14 no.4
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• pp.355-362
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• 2023

Physical exercise, especially intense exercise and high intensity interval training (HIIT) by trampoline, can lead to muscle injuries. These effects can be reduced with intelligent products made of nanocomposite materials. Most of these nanocomposites are polymers reinforced with silicon dioxide, alumina, and titanium dioxide nanoparticles. This study presents a polymer nanocomposite reinforced with silica. As a result of the rapid reaction between tetraethyl orthosilicate and ammonia in the presence of citric acid and other agents, silica nanostructures were synthesized. By substituting bis (4-amino phenoxy) phenyl-triptycene in N, N-dimethylformamide with potassium carbonate, followed by catalytic reduction with hydrazine and Pd/C, the diamine monomer bis (4-amino phenoxy) phenyl-triptycene is prepared. We synthesized a new polyaromatic (imide) with triptycene unit by sol-gel method from aromatic diamines and dianhydride using pyridine as a condensation reagent in NMP. PI readily dissolves in solvents and forms robust and tough polymer films in situ. The FTIR and NMR techniques were used to determine the effects of SiO₂ on the sol-gel process and the structure of the synthesized nanocomposites. By using a simultaneous thermal analysis (DTA-TG) method, the appropriate thermal operation temperature was also determined. Through SEM analysis, the structure, shape, size, and specific surface area of pores were determined. Analysis of XRD results is used to determine how SiO₂ affects the crystallization of phases and the activation energy of crystallization.

• Elastomers and Composites
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• v.44 no.1
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• pp.55-62
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• 2009

In this study, investigation on the polymerization characteristics of isoprene through nitroxide mediated controlled/"living" radical polymerization techniques was attempted. In the presence of acetol, linear increase of isoprene conversion with time and low polydispersities of the resulting polymers ($M_w/M_n$ < 1.5) were observed, which suggest successful controlled/"living" radical polymerization of isoprene. The microstructure of the resulting polyisoprene was composed of $\sim$ 22% of 3, 4, $\sim$30% of 1, 4-cis and $\sim$ 48% of 1, 4-trans. The optimum polymerization temperature was 145 $^{circ}C$, below which no significant polymerization behavior was observed. Non-cyclic nitroxide, such as di-tert-butyl nitroxide (DTBN) could not mediate the polymerization, whereas cyclic nitroxides (2, 2, 6, 6-tetramethyl-1-peperidine 1-oxyl (TEMPO) and 4-oxo-2, 2, 6, 6-tetramethyl-1-peperidine 1-oxyl (oxoTEMPO)) were successfully employed for the polymerization. However, isoprene dimerization reaction through Diels-Alder process was also observed at the given polymerization condition, which afforded a significant amount of limonene. Isoprene thermal autoinitiation was also possible, which was, however, considered to be not significant under the given polymerization condition.