• Advances in Traditional Medicine
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• v.7 no.1
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• pp.51-64
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• 2007

Mucus is an aqueous gel complex with a constitution of about 95% water, high molecular weight glycoprotein (mucin), lipid, salts etc. Mucus appears to represent a significant barrier to the absorption of some compounds. Natural mucoadhesive agent was isolated and purified from the aqueous extract of the seeds of prosopis pallida (PP). Formulated tablet with the isolated material by wet granulation method. Some natural edible substances are in consideration for candidates as mucoadhesive agents to claim more effective controlled drug delivery as an alternative to the currently used synthetic mucoadhesive polymers. Subjected the materials obtained from natural source i.e. PP and standard synthetic substance, sodium carboxymethyl cellulose for evaluation of mucoadhesive property by various in vitro and in vivo methods. Through standard dissolution test and a model developed with rabbit, evaluated in vitro controlled release and bioadhesive property of theophylline formulation. Mucoadhesive agent obtained from PP showed good mucoadhesive potential in the demonstrated in vitro and in viνo models. The results suggest that the mucoadhesive agent showed controlled release properties by their application, substantially. In order to assess the gastrointestinal transit time in vivo, a radio opaque X-ray study performed in healthy rabbit testing the same controlled release formulation with and without bioadhesive polymer. Plasma levels of theophylline determined by the HPLC method and those allowed correlations to the in vitro mucoadhesive study results. Better correlation found between the results in different models. PP may acts as a better natural mucoadhesive agent in the extended drug delivery system.

• The Korean Journal of Food And Nutrition
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• v.18 no.3
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• pp.254-264
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• 2005

This study was conducted to estimate the contents of heavy metals 'Hg, Cd, Pb, As, Zn, Cu, Cr, Mn' in some vegetables which were produced in Korea. The levels of heavy metals were determined using a mercury analyzer, an ICP(inductively coupled plasma spectrometer) and an AAS(atomic absorption spectrophotometer) after wet digestion. The values of heavy metals "mean(mini.~maxi.)" ppm(mg/kg) in some vegetables(raw of perilla leaf, chard, small water dropwort, water dropwort, kale, bud of aralia, pumpkin(round type) and pumpkin(long type) were as follows : Hg : 0.0021(0.0006~0.0054)mg/kg, Cd : 0.0035(ND*~0.0377)mg/kg, Pb : 0.0191(0.0023~0.0928)mg/kg, As : 0.0757(ND~0.5294)mg/kg, Zn : 2.6299(0.4478~6.8567)mg/kg, Cu : 1.0261(0.2046~8.9417)mg/kg, Cr : 0.1535 (0.0240~0.4982)mg/kg, Mn : 3.2476(0.3283~9.8280)mg/kg. This results showed that Mn was generally simillar to previous reports and Cd, Hg, Pb were lower than other reseaches, but As was little higher or Zn, Cu, Cr were higher than the levels of those reported contents in some vegetables on domestic supermarkets in Korea, Although tolerable limit of Hg and Cd is not in a regulation of WHO/FAO, these mean levels(Pb, As, Zn, Cu) are lower than recommended levels of WHO/FAO, Pb "0.1~2.0" mg/kg, As "1.0" mg/kg, Zn "5.0" mg/kg and Cu "0.1~50"mg/kg from vegetables in 'the tolerable contents of food' by the FAO/WHO, therefor some vegetables has set to evaluate their safeties.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.88.1-88.1
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• 2012

Silicon nanowires (SiNWs), due to their unusual quantum-confinement effects that lead to superior electrical and optical properties compared to those of the bulk silicon, have been widely researched as a potential building block in a variety of novel electronic devices. The conventional means for the synthesis of SiNWs has been the vapor-liquid-solid method using chemical vapor deposition; however, this method is time consuming, environmentally unfriendly, and do not support vertical growth. As an alternate, the electroless etching method has been proposed, which uses metal catalysts contained in aqueous hydrofluoric acids (HF) for vertically etching the bulk silicon substrate. This new method can support large-area growth in a short time, and vertically aligned SiNWs with high aspect ratio can be readily synthesized with excellent reproducibility. Nonetheless, there still are rooms for improvement such as the poor surface characteristics that lead to degradation in electrical performance, and non-uniformity of the diameter and shapes of the synthesized SiNWs. Here, we report a facile method of SiNWs synthesis having uniform sizes, diameters, and shapes, which may be other than just cylindrical shapes using a modified nanosphere lithography technique. The diameters of the polystyrene nanospheres can be adjustable through varying the time of O2 plasma treatment, which serve as a mask template for metal deposition on a silicon substrate. After the removal of the nanospheres, SiNWs having the exact same shape as the mask are synthesized using wet etching technique in a solution of HF, hydrogen peroxide, and deionized water. Different electrical and optical characteristics were obtained according to the shapes and sizes of the SiNWs, which implies that they can serve specific purposes according to their types.

• Archives of Pharmacal Research
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• v.13 no.2
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• pp.151-160
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• 1990

In order to develop a controlled-release oral drug delivery system (DDS) which sustains the plasma acetaminophen (AAP) concentration for a certain period of time, microporous membrane-coated tablets were prepared and evaluated in vitro. Firstly, highly water-soluble core tablet of AAP were prepared with various formulations by wet granulation and compression technique. Then the core tablets were coated with polyvinychloride (PVC) in which micronized sucrose particles were dispersed. Effect of formula compositions of core tablets and coating suspensions on the pharmaceutical characteristics such as drug release kinetics and membrane stability of the coated tablets was investigated in vitro. AAP was released from the coated tablets as a zero-order rate in a pH-independent manner. This independency of AAP release to pH change from 1.2 to 7.2 is favorable for the controlled oral drug delivery, since it will produce a constant drug release in the stomach and intestine regardless of the pH change in the GI tract. Drug release could be extended upto 10 h according to the coating condition. The release rate could be controlled by changing the formula compositions of the core tablets and coating suspensions, coat weight per each tablet, and especially PVC/sucrose ratio and particle size of the sucrose in the coating suspension. The coated tablets prepared in this study had a fairly good pharmaceutical characteristics in vitro, however, overall evaluation of the coated tablet should await in vivo absorption study in man.

• Journal of the East Asian Society of Dietary Life
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• v.15 no.4
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• pp.465-474
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• 2005

This study was conducted to estimate the contents of heavy metals 'mercury(Hg), cadmium(Cd), lead(Pb), arsenic(As), zinc(Zn), copper(Cu), chrome(Cr) and manganese(Mn)' in root vegetables which were produced in Korea. The levels of heavy metals were determined using a mercury analyzer, an ICP(inductively coupled plasma spectrometer) and an AAS(atomic absorption spectrophotometer) after wet digestion. The values of heavy metals 'mean(minimum-maximum)' mg/kg(ppm) in root vegetables (radish, turnip, carrot, ginger, edible burdock, taro, Chinese yam, east indian lotus) were as follows ; Hg : 0.0019(0.0002${\~}$0.0062), Cd : 0.0088(ND${\~}$0.0402), Pb : 0.021(ND${\~}$0.1070), As : 0.0401(ND${\~}$0.1732), Zn : 1.865(0.4186${\~}$6.9319), Cu : 0.648 (0.1826${\~}$4.0172), Cr : 0.121(0.0132${\~}$1.2030), and Mn : 2.730(0.0477${\~}$10.0468) mg/kg. These results showed that Hg were generally similar to and Cd was lower but Ph, As, Zn, Co, Mn were little higher than the levels of those reported contents in root vegetables on retail markets in Korea. Although the tolerable limit of Cd and Hg is not set in a regulation of WHO/FAO, the tested mean levels(Pb, As, Zn, Cu) were lower than the regulated ones of WHO/FAO, Pb '0.1-2.0', As '1.0', Zn '5.0', and Cu 0.1${\~}$50 mg/kg from vegetables. Therefore, root vegetables sold in the retail markets were evaluated as safe in terns of the heavy metal contents.

• Journal of Pharmaceutical Investigation
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• v.29 no.4
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• pp.349-353
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• 1999

A novel polymeric tablet of tinidazole (TD) was formulated to treat Helicobacter pylori and Giardia lambria more efficiently with reduced hepatotoxicity by controlling the release of TD after oral administration. TD tablets containing various concentrations of either xanthan gum (XG, viscosity enhancer) and/or polycarbophil (PC, mucoadhesive) were prepared by the wet granulation method. In vitro release of TD into pH 2.0 and pH 5.0 buffer solutions was observed at 37°C by using an USP dissolution tester and an UV (313 nm) spectrophotometer. In vivo absorption of TD tablets was investigated in rabbits by measuring the blood concentration of TD after oral administration using a HPLC. Compared to a commercial TD tablet, in vitro release of TD in both pH 2.0 and pH 5.0 buffer solutions significantly decreased as the concentration: of XG or PC in the tablet increased up to 30%. However, when XG and PC was added in combination, TD was completely released in a pH 5.0 buffer solution within 8 hours, whereas the release of TD in pH 2.0 buffer solution significantly decreased. TD in a commercial tablet was rapidly absorbed after oral administration in rabbits. After oral administration of the polymeric tablets that contain both XG and PC, plasma concentration of TD dramatically decreased. Since the oral absorption of TD significantly decreased by the addition of XG and PC in the tablets while TD completely released in a pH 5.0 buffer solution, it was speculated that more TD was retained in the gastrointestinal tract. Thus, it was possible to control the release of TD by changing the content of XG and/or PC in the tablet, thereby manipulating the release rate and the gastrointestinal retention of TD after oral administration in rabbits.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.617-620
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• 1999

In this study, the polarization e(fecal and the birefringence effect of amorphous germanium (a-Ge) thin films were investigated by using linearly polarized He-Ne laser beam. The a-7e thin films were deposited on the quarts substrate by plasma enhanced chemical vapor deposition (PECVD) and thermal vacuum evaporation In order to obtain the optimum grating arrays, inorganci resists such as Si$_3$N$_4$ and a-Se$_{75}$ Ge$_{25}$ , were prepared with the optimized thickness by Monte Carlo (MC) simulation. As the results of MC simulation, the thickness ofa-Se$_{75}$ Ge$_{25}$ resist was determined with Z$_{min}$ of 360$\AA$ . The resists were exposed to Ga$^{+}$-FIB with accelerating energies of 50 keV, developed by wet etching, and a-Ge thin film was etched by reactive ion-etching (RIE). Finally, we were obtained grating arrays which grating width and linewidth are 0.8${\mu}{\textrm}{m}$, respectively and we studied the polarization and birefringence effect in transmission grating array made of high refractive amorphous material, and the applicability as waveplates and polarizers in optical device.e.e.

• Journal of the Semiconductor & Display Technology
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• v.7 no.1
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• pp.1-5
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• 2008

In this paper, we fabricated pressure difference type gas flow sensor using only dry etching technology by ICP-RIE(inductive coupled plasma reactive ion etching). The sensor's structure consists of a common shear stress type piezoresistive pressure sensor with an orifice fabricated in the middle of the sensor diaphragm. Generally, structure like diaphragm is fabricated by wet etching technology using TMAH, but we fabricated diaphragm by only dry etching using ICP-RIE. To equalize the thickness of diaphragm we applied insulator($SiO_2$) layer of SOI(Si/$SiO_2$/Si-sub) wafer as delay layer of dry etching. Size of fabricated diaphragm is $1000{\times}1000{\times}7\;{\mu}m^3$ and overall chip $3000{\times}3000{\times}7\;{\mu}m^3$. We measured the variation of output voltage toward the change of gas pressure to analyze characteristics of the fabricated sensor. Sensitivity of fabricated sensor was relatively high as about 1.5mV/V kPa at 1kPa full-scale. Nonlinearity was below 0.5%F.S. Over-pressure range of the fabricated sensor is 100kPa or more.

• Composites Research
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• v.36 no.5
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• pp.342-348
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• 2023

There has been increasing demand for real-time monitoring of body and ambient temperatures using wearable devices. Graphene-based thermistors have been developed for high-performance flexible temperature sensors. In this study, the temperature coefficient of resistance (TCR) of monolayer graphene was controlled by coating polyethylenimine (PEI) on graphene surfaces to enhance its temperature-sensing performances. Monolayer graphene grown by chemical vapor deposition (CVD) was wet-transferred onto a target substrate. To facilitate the interfacial doping by PEI, the hydrophobic graphene surface was altered to be hydrophilic by oxygen plasma treatments while minimizing defect generation. The effect of PEI doping on graphene was confirmed using a back-gated field-effect transistor (FET). The CVD-grown monolayer graphene coated with PEI exhibited an improved TCR of -0.49(±0.03) %/K in a temperature range of 30~50℃.

• Biomolecules & Therapeutics
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• v.32 no.1
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• pp.162-169
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• 2024

Particulate matter (PM) constitutes a hazardous blend of organic and inorganic particles that poses health risks. Inhalation of fine airborne PM with a diameter of ≤ 2.5 ㎛ (PM_2.5) can lead to significant lung impairments. (+)-afzelechin (AZC), a natural compound sourced from Bergenia ligulata, boasts a range of attributes, including antioxidant, antimicrobial, anticancer, and cardiovascular effects. However, knowledge about the therapeutic potential of AZC for patients with PM_2.5-induced lung injuries remains limited. Thus, in this study, we investigated the protective attributes of AZC against lung damage caused by PM_2.5 exposure. AZC was administered to the mice 30 min after intratracheal instillation of PM_2.5. Various parameters, such as changes in lung tissue wet/dry (W/D) weight ratio, total protein/total cell ratio, lymphocyte counts, levels of inflammatory cytokines in bronchoalveolar lavage fluid (BALF), vascular permeability, and histology, were evaluated in mice exposed to PM_2.5. Data demonstrated that AZC mitigated lung damage, reduced W/D weight ratio, and curbed hyperpermeability induced by PM_2.5 exposure. Furthermore, AZC effectively lowered plasma levels of inflammatory cytokines produced by PM_2.5 exposure. It reduced the total protein concentration in BALF and successfully alleviated PM_2.5-induced lymphocytosis. Additionally, AZC substantially diminished the expression levels of Toll-like receptors 4 (TLR4), MyD88, and autophagy-related proteins LC3 II and Beclin 1. In contrast, it elevated the protein phosphorylation of the mammalian target of rapamycin (mTOR). Consequently, the anti-inflammatory attribute of AZC positions it as a promising therapeutic agent for mitigating PM_2.5-induced lung injuries by modulating the TLR4-MyD88 and mTOR-autophagy pathways.