• Title/Summary/Keyword: Spectroscopy Analysis

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Antimicrobial Chitosan-silver Nanocomposite Film Prepared by Green Synthesis for Food Packaging (녹색합성법에 기인한 식품포장용 키토산-은나노 항균 복합필름의 개발)

  • Kyung, Gyusun;Ko, Seonghyuk
    • Korean Journal of Food Science and Technology
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    • v.46 no.3
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    • pp.347-351
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    • 2014
  • We studied the green synthesis and antibacterial activity of chitosan-silver (Ag) nanocomposite films for application in food packaging. Green synthesis of Ag nanoparticles (AgNPs) was achieved by a chemical reaction involving a mixture of chitosan-silver nitrate ($AgNO_3$) in an autoclave at 0.1 MPa, $121^{\circ}C$, for 15-120 s. The formation of AgNPs in chitosan was confirmed by both UV-Visible spectrophotometry and transmission electron microscopy (TEM) and the effects of chitosan-$AgNO_3$ concentration and reaction time on the synthesis of AgNPs in chitosan were examined. The resulting chitosan-Ag composite films were characterized by various analytical techniques and their antibacterial activity was evaluated based on the formation of halo zones around films, indicating inhibition of the growth of Escherichia coli. A fourier-transform infrared (FTIR) spectroscopy analysis showed that free amino groups in chitosan acted as effective reductants and AgNP stabilizers. The composite films exhibited enhanced antibacterial activity with increasing Ag content on the surface of as-prepared composite films.

Development of Disposable Immunosensors for Rapid Determination of Sildenafil and Vardenafil in Functional Foods

  • Vijayaraj, Kathiresan;Lee, Jun Hyuck;Kim, Hyung Sik;Chang, Seung-Cheol
    • Journal of Food Hygiene and Safety
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    • v.32 no.2
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    • pp.83-88
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    • 2017
  • We introduced disposable amperometric immunosensors for the detection of Sildenafil and Vardenafil (SDF/VDF) based on screen printed carbon electrodes. The developed immunosensors were used as a non-competitive sandwich-type enzyme immunoassay with a horseradish peroxidase label. The sensors were constructed on screen printed carbon electrodes by the simple electrochemical deposition of a reduced graphene oxide and chitosan (ErGO-CS) composite. To evaluate the sensing chemistry and optimize the sensor characteristics, a series of electrochemical experiments were carried out including electrochemical impedance spectroscopy, cyclic voltammetry and amperometry. The sensors showed a linear response to SDF/VDF concentrations in a range from 100 pg/mL to 300 ng/mL. The lower detection limit was calculated to be 55 pg/mL, the sensitivity was calculated to be $1.02{\mu}Ang/mL/cm^2$, and the sensor performance exhibited good reproducibility with a relative standard deviation (RSD) of 7.1%. The proposed sensing chemistry strategy and the sensor format can be used as a simple, cost-effective, and feasible method for the in-field analysis of SDF/VDF in functional or health supplement food samples.

A Study on the Change of the Adsorption Process of VOCs in the Materials Prepared from the Intercalation Reaction (층간 삽입반응으로 얻어진 화합물을 이용한 휘발성 유기화합물의 흡착과정 변화에 대한 연구)

  • Ahn, Beom-Shu
    • Journal of the Korean Applied Science and Technology
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    • v.34 no.4
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    • pp.799-806
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    • 2017
  • The potential use of modified clays in the adsorption of vapor phase benzene and toluene was investigated. The modified clays OC-CPC, IOC, and Al-PILC were prepared for comparative purposes and were characterized using infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction. It was confirmed the intercalation of the aluminium pillar in IOC and Al-PILC, as well as the introduction of cetylpyridinium. The adsorption studies showed a great affinity of benzene and toluene for OC-CPC due to the hydrophobic character that resulted and also to the increase in the interlaminar distance. IOC showed a lower affinity for the benzene and toluene, followed by Al-PILC. Natual clay had no affinity for benzene and toluene due to its hydrophilic nature. Clay materials having a laminar structure can be chemically modified, changing their physiochemical characteristics, such as interlaminar distance, surface area, pore size, and chemical affinity. In this study, it was focused on obtaining modified clays to be used for the adsorption of volatile organic chemicals.

A Study on Co-precipitation of Indium Hydroxide (In(OH)3) for the Recovery and Determination of Trace Heavy Metals (인듐 수산화물(In(OH)3)의 공동침전을 이용한 미량의 중금속 회수 및 분석방법 연구)

  • Kwon, Seul-woo;Son, Seong-Hun;Lee, Man Seung;Nam, Sang-Ho
    • Resources Recycling
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    • v.26 no.4
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    • pp.50-55
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    • 2017
  • Determination of trace elements in a sample including complicated matrix is very difficult due to the interference by the matrix. Therefore, if the trace elements can be separated from the complex sample matrix and determined, the interference effects can be reduced, and it is very helpful for the overall analysis. In this study, the analytes of trace elements were separated from the sample matrix by co-precipitation with trace elements using indium hydroxide ($In(OH)_3$), then detected by inductively coupled plasma-atomic emission spectrometer (ICP-AES). Above all, the optimal conditions for the co-precipitation of elements with indium hydroxide were experimentally established. At last, salt was analyzed by the developed analytical method. No heavy metals were not found in Shinan Jeungdo salt, but trace amounts of several heavy metals except for cadmium were found in Cheonnam Yongkwang salt.

Effect of Light Transmission on Composition and Somatic Cell count of Raw Milk (분광된 빛의 주사가 원유내 성분에 미치는 영향)

  • Ko, Han-Jong;Kim, Ki-Youn;Min, Young-Bong;Nishizu, Takahisa;Yun, Yong-Chul;Kim, Hyeon-Tae
    • Journal of agriculture & life science
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    • v.46 no.1
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    • pp.189-194
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    • 2012
  • Measurement of compositions and somatic cells in raw milk by chemical methods usually requires a lot of time, skilled labor and expensive analytical equipments. Recently, near-infrared reflectance spectroscopy (NIRS), which is a rapid, cost-effective and non-destructive technique, has been extensively used for safety and quality evaluation in the field of dairy products. However, less study has been performed to evaluate the effect of transmitted light on milk quality during NIRS analysis. Therefore, the objective of this study was to analyze the changes in milk quality using transmitted light. Raw milk samples collected from dairy farm from Siga prefecture in Japan were analyzed for fat, protein, lactose, solids not fat, total solids, milk urea and citric acid using the Milko scan 4000. Somatic cells in raw milk samples were counted by the Fossomatic 5000. Transmittance spectra of 50 ml raw milk samples were obtained by the Lax-Cute lighter in the 400 nm or less, 689 nm, 773 nm, 900 nm and 979 nm. As a result, milk fat as well as somatic cell count was increased by 2.6% and 9.0%, respectively. The other compositions were, however, changed within the relative error of the measurement. Further studies are needed to apply raw milk quality evaluation using the UV band by accumulating more samples and more data.

Synthesis and Biocompatibility Study of Hydrogel for Patch Sensor in Non-invasive Glucose Monitoring System (무채혈 혈당 측정시스템의 Patch Sensor용 수화젤의 합성 및 생체적합성에 관한 연구)

  • Kwon, Jeong-Woo;Kim, Dong-Chul;Yoon, In-Joon;Jeong, Yoon-Na;Jeong, Ji-Young;Hwang, In-Sik
    • Polymer(Korea)
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    • v.33 no.2
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    • pp.111-117
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    • 2009
  • This study aims to verify for humans the suitability of the enzyme-fixed hydrogel used for the patch sensor of the blood sugar testing system without blood sampling, which utilizes reverse iontophoresis. Using acrylate monomers, hydrogel was synthesized to which a certain unit of enzyme is fixed. In order to analyze the material property of the synthesized hydrogel, a structural analysis was performed using FT-IR spectroscopy, while the DSC was used to verify the thermal stability. In addition, with the UV-Vis spectrophotometer, it was verified that the degree of active enzyme is at least 50% greater than the standard product. The SEM was used to verify secure fixation of the enzyme onto the surface. As a result, it was observed that the enzyme is successfully fixed to the surface. Since the hydrogel makes direct contact with a patient's skin, it is essential to evaluate the toxicity when making direct contact with the skin. For that purpose, various sets of tests were undertaken according to the ISO 10993-cytotoxicity, intracutaneous reactivity, skin irritation test and maximization sensitization. Consequently, it was successfully verified that the enzyme-fixed hydrogel have bioavailability.

Raman Spectromter for Detection of Chemicals on a Road (지표면 화학물질 측정을 위한 라만분광장치)

  • Ha, Yeon Chul;Lee, Jae Hwan;Koh, Young Jin;Lee, Seo Kyung;Kim, Yun Ki
    • Korean Journal of Optics and Photonics
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    • v.28 no.3
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    • pp.116-121
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    • 2017
  • In this paper, a Raman spectrometer is designed to detect chemicals contaminating the ground. The system is based on Raman spectroscopy, which is spectral analysis of scattered light from chemicals, induced by a laser. The system consists of a transmitting-optics module with a laser to induce Raman-scattered light from the sample, a receiving-optics module to collect the scattered light, and a spectrograph to separate the collected light into a wavelength spectrum. The telescope, a part of the receiving-optics module, is designed to produce a focal spot in the same position for variable measurement distances using the code V simulator, considering the distance change between the system and the road. The Raman spectra of 12 chemicals on a glass surface and on a concrete sample were measured. Intensity differences between the Raman spectra acquired on a glass surface and on a concrete sample were observed, but the characteristics of the spectra according to the chemicals on them were similar. Additionally, the Raman spectrum of PTFE (polytetrafluoroethylene) was measured at various distances. The measured and simulated optical throughputs were similar. In conclusion, it is confirmed that with this system the Raman spectrum can be measured, irrespective of the distance change.

A Study to Recover Si from End-of-Life Solar Cells using Ultrasonic Cleaning Method (초음파 세척법을 이용한 사용 후 태양광 셀로부터 Si 회수 연구)

  • Lee, Dong-Hun;Go, Min-Seok;Wang, Jei-Pil
    • Resources Recycling
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    • v.30 no.5
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    • pp.38-48
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    • 2021
  • In this study, we determine the optimal process conditions for selectively recovering Si from a solar cell surface by removal of impurities (Al, Zn, Ag, etc.). To selectively recover Si from solar cells, leaching is performed using HCl solution and an ultrasonic cleaner. After leaching, the solar cells are washed using distilled water and dried in an oven. Decompression filtration is performed on the HCl solution, and ICP-OES (Inductively Coupled Plasma Optical Emission spectroscopy) full scan analysis is performed on the filtered solution. Furthermore, XRD (X-ray powder diffraction), XRF (X-ray fluorescence), and ICP-OES are performed on the dried solar cells after crushing, and the purity and recovery rate of Si are obtained. In this experiment, the concentration of acid solution, reaction temperature, reaction time, and ultrasonic intensity are considered as variables. The results show that the optimal process conditions for the selective recovery of Si from the solar cells are as follows: the concentration of acid solution = 3 M HCl, reaction temperature = 60℃, reaction time = 120 min, and ultrasonic intensity = 150 W. Further, the Si purity and recovery rate are 99.85 and 99.24%, respectively.

Understanding Interfacial Charge Transfer Nonlinearly Boosted by Localized States Coupling in Organic Transistors (Carbon Nano Tube 및 산화그래핀을 첨가한 폴리우레아 복합재 제조 및 그 화학적 특성 분석)

  • Kim, Hyeongtae;Lee, Jihyun;An, Woo-Jin;Park, Jun Hong
    • Journal of Adhesion and Interface
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    • v.22 no.4
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    • pp.136-143
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    • 2021
  • Polyurea has been investigated as a polymer matrix for composite materials because of its high mechanical strength. Although polyurea has a similar chemical structure to polyurethane, it has much higher strength and durability. In this study, the fabrication of polyurea composites reinforced with carbon nanotube (CNT) and graphene oxide (GO) is demonstrated to enhance the tensile strength of the glass fibers composite. Using FTIR and Raman spectroscopies, the chemical structures of polyurea, CNT, and GO are investigated. As a result, spectroscopy analysis reveals that the chemical structure of CNT, GO, and polyurea is maintained during the fabrication of the composite structure. Scanning electron microscopy reveals the uniform distribution of CNT and GO across the polyurea matrix. The reinforcement of 1 wt% CNT in polyurea enhances the tensile strength of CNT/polyurea composites. In contrast, the reinforcement of GO in polyurea induces the degradation of the tensile strength of GO/polyurea composites.

Preparation of Non-Fluorinated Water Repellent Coating Films Using Methyltrimethoxysilane and Trimethylethoxysilane (Methyltrimethoxysilane과 Trimethylethoxysilane을 이용한 비불소계 발수 코팅 도막의 제조)

  • Kim, Dong Gu;Lee, Byoung Hwa;Song, Ki Chang
    • Korean Chemical Engineering Research
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    • v.57 no.2
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    • pp.177-184
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    • 2019
  • Non-fluorinated water repellent coating solutions were obtained using methyltrimethoxysilane (MTMS) and trimethylethoxysilane (TMES) as precursors. The solutions were spin-coated on a cold-rolled steel sheet and cured thermally to prepare water repellent coating films. During this process, the effect of molar ratio of TMES/MTMS was studied for the hydrophobic properties of the coating films. Hydrophobic properties of coating films were characterized using contact angle measurement, surface morphology analysis and infrared spectroscopy. When the molar ratio of TMES/MTMS was varied from 0 to 30, the contact angle of the un-coated cold-rolled steel sheet was $30^{\circ}$, whereas when the molar ratio of TMES/MTMS was 1, the contact angle increased to $104^{\circ}$ and water repellency was significantly improved. In the case of TMES/MTMS molar ratios of 10, 15, 25 and 30, the contact angles of coating films showed $109^{\circ}$, $114^{\circ}$, $117^{\circ}$ and $144^{\circ}$, respectively. At this time, the hydrophobicity of the coating films was improved by the increase of the surface roughness and the content of the methyl component at the coating surface. In particular, when the molar ratio of TMES/MTMS was 30, the overall surface roughness was greatly increased due to the presence of surface particles as well as the water repellency due to methyl groups of TMES, resulting in super hydrophobicity of $144^{\circ}$.