A Novel Injectable pH–Temperature Sensitive Hydrogel Containing Chitosan–Insulin Electrosprayed Nanosphere Composite for an Insulin Delivery System in Type I Diabetes Treatment

Thuy An Trinh,Thai Minh Duy Le,Hoang Gia Vinh Ho,Thi Cam Thach To,Vu Viet Linh Nguyen,Dai Phu Huynh,Doo Sung Lee 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.1

Faculty of Materials Technology, Ho Chi Minh University of Technology (HCMUT)/Vietnam National University Ho Chi Minh City; ¹School of Chemical Engineering and Theragnostic Macromolecules Research Center, Sungkyunkwan University; ²Vietnam National University Ho Chi Minh City/National Key Laboratory of Polymer and Composite Materials, Ho Chi Minh University of Technology, Vietnam National University; ³Faculty of Materials Technology, Ho Chi Minh University of Technology (HCMUT)/ Vietnam National University Ho Chi Minh City/Research Center for Polymeric Materials, Ho Chi Minh University of Technology, Vietnam National University In this research, a novel insulin composite delivery system was prepared and characterized. Insulin drug was loading in chitoshan nanospheres using electrospraying method, a pH- and temperature-sensitive biodegradable hydrogel, which is an oligomer serine-poly(lactide)-poly(ethylene glycol)-poly (lactide)-oligomer serine (OS-PLA-PEG-PLA-OS) pentablock copolymer was used as a matrix to containing chitosan–insulin electro sprayed nanospheres (CIN). The properties of the OS-PLA-PEG-PLA-OS pentablock copolymer and the chitosan–insulin nanoparticles such as sol-gel transition, degradation in vitro and in vivo were characterized. The results showed that the chitosan–insulin nanospheres uniformly distributed in the matrix had a reinforcing effect on the mechanical properties and prolonged the degradation time of the hydrogel depot under body conditions. In addition, the cytotoxicity experiment results indicate that the composite could be used as a biomaterial for drug delivery system. The composite solutions accommodating different concentrations of the chitosan–insulin nanospheres were subcutaneously injected into induced diabetic BALB/c mice to study the in vivo insulin-release profile. The result showed that insulin concentrations in blood plasma were maintained at a steady-state level. Furthermore, the bio-properties of the insulin were retained and it showed a blood glucose level reducing effect for more than 60 hours after injection to a streptozotocin (STZ)-induced diabetic mouse model. The results suggested that this injectable pH–temperature sensitive hydrogel containing chitosan– insulin electro sprayed nanosphere composites has promising potential applications for type 1 diabetes treatment.

냉수공장에서 열전달을 고려한 응축기와 증발기의 물 압력강하 특성

Nguyen Minh Phu,이근식(Geun Sik Lee) 대한기계학회 2011 大韓機械學會論文集B Vol.35 No.12

물 냉각기의 응축기와 증발기의 형상(길이, 관 직경, 관수, 통로 수)은 설비비용에 관련된 열전달 면적과 운전비용에 관련된 압력강하와의 조화로 결정될 수 있다. 물 냉각기 (냉동사이클)의 쉘-관 형상의 열교환기(응축기와 증발기)의 관 내부로 물이 통과할 때, 주어진 냉각부하와 요구조건을 만족하면서, 물 압력강하가 작은 설계조건에 초점을 맞추었다. 상업용 강화튜브의 사용과 상용 소프트웨어를 사용한 해석결과의 검증으로 실용성과 신뢰성 확보를 도모하였다. 해석결과, 관 통로 수를 적게, 관 직경을 크게, 관 수를 많게 선정하면, 관 길이를 짧게 하므로 물측 압력강하를 줄일 수 있었다. 그러나, 관수가 특정값보다 많을 때는 오히려 작은 관 직경을 사용하는 것이, 내부열저항의 감소로 인한 단위 길이 당 총 열저항 감소 때문에, 관 길이를 짧게 하여 설비비용을 줄일 수 있었다. The configurations of the evaporator and condenser of a water chiller can be determined from the trade-off between the heat transfer area, which is related to the capital cost and the pressure drop, which is associated with the operational cost. In this study, the design of the water chiller focused on minimizing the water pressure drop of both condenser and evaporator for given cooling capacity and requirements. Commercial enhanced tubes were employed to simulate real-life conditions. The results of the present analysis were compared with those obtained by HTRI software for verifying them. The results indicated that a reduction in the water pressure drop, which is associated with the short length of a tube, can be effected by decreasing the number of tube passes and increasing the number of tubes and the tube diameter. However, using a large number of tubes with smaller diameters can reduce the capital cost because the tubes are short. The reduction of the capital cost is due to the fact that a small-diameter tube has low internal thermal resistance and hence contributes to a decrease in the overall thermal resistance per unit length.

Modelling and experimental validation for off-design performance of the helical heat exchanger with LMTD correction taken into account

Nguyen Minh Phu,Nguyen Thi Minh Trinh 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.7

Today the helical coil heat exchanger is being employed widely due to its dominant advantages. In this study, a mathematical model was established to predict off-design works of the helical heat exchanger. The model was based on the LMTD and e-NTU methods, where a LMTD correction factor was taken into account to increase accuracy. An experimental apparatus was set-up to validate the model. Results showed that errors of thermal duty, outlet hot fluid temperature, outlet cold fluid temperature, shell-side pressure drop, and tube-side pressure drop were respectively ±5%, ±1%, ±1%, ±5% and ±2%. Diagrams of dimensionless operating parameters and a regression function were also presented as design-maps, a fast calculator for usage in design and operation of the exchanger. The study is expected to be a good tool to estimate off-design conditions of the single-phase helical heat exchangers.

Augmented heat transfer and friction investigations in solar air heater artificially roughened with metal shavings

Nguyen Minh Phu,Vo Tuyen,Tu Thien Ngo 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.7

The paper presents the effect of the Reynolds number, relative roughness height and relative roughness pitch on the heat transfer and pressure loss in a solar air heater. A novel absorber plate with metal shavings from the turning of a steel shaft is employed to reduce the cost of production and to be available for the manufacturing industry. The parameters studied ranged from 5000 to 25000 for the Reynolds number, from 4.7 to 9.4 for the relative roughness pitch (P/e) and from 0.26 to 0.43 for the relative roughness height (e/D h ). The results show that there are some characteristics that differ from the published studies. The optimum e/D h is 0.35 to obtain the highest thermo-hydraulic performance parameter, and the parameter increases with a decrease in P/e. Within the scope of the study, the maximum thermo-hydraulic performance parameter is approximately 1.5. The correlations between the Nusselt number and the friction factor are developed based on the experimental data. The results from the correlations and from the experimental data are fairly in agreement.

Evaluation of JPEG XT integer coding mechanisms

Nguyen Minh Phu,Seungcheol Choi(최승철),Oh-Jin Kwon(권오진) 대한전자공학회 2019 대한전자공학회 학술대회 Vol.2019 No.11

JPEG XT has been designed to a high dynamic range (HDR) image compression which can be backward compatible with the conventional JPEG image coding standard. It consists of two layers: the base and the extension layer. The base layer contains a tone-mapped version of the HDR image and the extension layer contains residual information to reconstruct the HDR image on the basis the base layer. However, most studies about JPEG XT did not take into an account all features that can affect the performance while they have focused on the tone mapping operation and comparison of the coding performance between different profiles. In this study, we conducted experiments to compare two different HDR encoding mechanisms: open loop and closed loop, which is done during the prediction of the HDR information. Experimental results show that the closed loop exhibits better and relatively stable HDR-VDP-2 performance for various tone mapping methods.

관 내부 비등이 있는 수직관 외부 얼음 형성 연구

Nguyen Minh Phu,이근식(Geun Sik Lee) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.5

얼음 제조와 잠열 저장 등에서 열전달 향상을 위하여 수직관 내부를 저온의 냉매가 흐르도록 하여, 관 외부의 물로부터 열을 흡수하여 얼음이 형성되는 현상에 대하여 해석되었다. 상변화 열전달 및 비등 열전달 관계식들이 도입되어 해석되었으며, 작동유체로는 냉매 22와 냉매 134a가 사용되었으며, 이들의 건도는 0-0.8 범위이다. 5시간 얼음제조과정을 기준으로 할 때, 최초 2 시간 이내에 형성되는 얼음의 양이 총 얼음 양의 약 45%이상을 차지하였다. 얼음의 열저항이 얼음 형성에 미치는 영향은 비등 열전달계수, 열플럭스와 건도와 같은 다른 변수들에 비하여 현저하였다. 냉매 22의 열전달 계수는 냉매 134a 의 경우보다 높다. 따라서 냉매 134a 보다 냉매 22를 사용한 경우의 얼음 두께가 두껍다. 열전달 면적에 대한 얼음 질량의 비를 살펴보면, 냉매 22의 경우가 냉매 134a 의 경우보다 높다. An ice making model has been developed and analyzed. In order to improve heat transfer, ice is frozen on the outer surface of a tube cooled directly with boiling refrigerant to flow internally. The model is based on available expressions about phase change heat transfer and boiling heat transfer coefficient. R22 and R134a were used as heat transfer fluids and their vapor qualities were in range of 0 to 0.8. The mass of ice formed within 2 hour took up nearly half of total mass of ice. The results show that influence of ice thermal resistance on other parameters such as boiling heat transfer coefficient, heat flux and quality is remarkably higher, compared with until the ice has not been formed yet. Heat transfer coefficient of R22 is higher than that of R134a. Therefore, ice thickness in case of R22 is thicker and shorter than that in R134a. The ratio of mass of ice to heat transfer area for R22 is also higher than that for R134a. The model and results can be applied to both ice making and latent thermal energy storage.

A Magnetization Study of Prussian-blue Analogue Na<SUB>x</SUB>Mn<SUB>y</SUB>[Fe(CN)<SUB>6</SUB>]

Nguyen Van Minh,Phung Kim Phu,Nguyen Minh Thuan,In-Sang Yang 한국자기학회 2008 Journal of Magnetics Vol.13 No.4

In this report, we present the results of a study on the effects of the particle size on the properties of the Prussian blue (PB) analog NaxMny[Fe(CN)?]. A novel synthesis method of the NaxMny[Fe(CN)?] nano-particles using an organic solvent, formamide, is employed. The size of the PB particles is found to be 100-150 ㎚ for the samples prepared in the formamide solvent, which is much smaller than that of the samples prepared using water only. The broadening of the X-ray diffraction peaks of the nano-sized PB samples is attributed to the lattice disorder and a dramatic reduction in the particle size. The compositions of the samples are confirmed by an energy-dispersive X-ray analysis (EDAX), and the result proves that the samples are actually NaxMny[Fe(CN)?] Prussian blue. The UV-vis spectra show a broad intervalence charge-transfer (CT) band in the visible region between 400 and 700 ㎚, and the absorption decreases abruptly in the green region for the nano-sized PB sample. A divergence between the field cooled (FC) and zero field cooled (ZFC) magnetization curves is observed for the nano-sized PB sample at 11 K, indicating that nanoparticles in the sample are single domain superparamagnets with a blocking temperature of 11 K. Our results reveal that the nano-sized PB samples show significantly different optical and magnetic properties than those of the bulk PB samples.

Overall Optimization and Exergy Analysis of an Air Conditioning System Using a Series-Series Counterflow Arrangement of Water Chillers

Nguyen Minh Phu 대한설비공학회 2019 International Journal of Air-Conditioning and Refr Vol.27 No.4

When water chillers are arranged in series-series counterflow (SSCF), the compressor lift of each chiller is decreased in comparison with that of water chillers in parallel. This means that the compressor power of SSCF chillers is lower than that of parallel chillers. In this paper, models of the main components in an air conditioning system were developed and verified to predict the behaviors of the whole system with respect to SSCF chillers. The results showed that performance was maximized with three SSCF chillers when the system was operated with normal set points. The performance was further improved to 26% and decreased with the number of SSCF chillers when the system was operated with optimal set points. The SSCF chiller system also demonstrated higher exergy efficiency regardless of the number of SSCF chillers. The irreversibility of components in SSCF chillers was rather low. However, the irreversibility of the cooling tower and cooling coil was slightly higher and lower, respectively, than those in the parallel chiller system.

다수의 직렬-직렬 대향류 물 냉각기를 사용한 공조시스템의 성능

Nguyen Minh Phu,이근식(Geun Sik Lee) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11

When water chillers are arranged in series-series counter-flow (SSCF), the compressor lift of each chiller is decreased, in contrast to water-chillers in parallel. That means that the compressor power of SSCF chillers is lower than that of parallel chillers. In this paper, the models of main components in an air conditioning system were formed and verified in order to predict the performance of the whole system with SSCF chillers. Results were shown that the performance had maximum with 3 SSCF chillers when the system was operated with the normal set points. 26% enhancement of the performance was achieved with the optimal-set-point operation in the case of 3 SSCF chillers but no advantage was found in the cases of more than 4 SSCF chillers.

Unsteady analysis of a solar air heater with sensible heat storage using 2D finite difference approximation

Nguyen Minh Phu,Lai Hoai Nam,Nguyen Le Hong Son 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.11

In this paper, an air collector with sensible heat storage is numerically solved using the finite difference method. The change in temperatures of the glass, airflow, and absorber plate is assumed to be unidirectional. Meanwhile, heat conduction in the storage material is considered in two dimensions. Six storage materials containing brick, granite, slag, limestone, sandstone, and concrete are simulated unsteadily. Numerical techniques, including an implicit method, an upwind scheme, the Thomas algorithm, and the ADI method, are used to solve a system of differential equations describing the collector. The charging and discharging mechanisms are effectively explained by the two-dimensional temperature distribution of the storage material. Results indicate that the charge and discharge periods are up to 16:00 PM and 24:00 PM, respectively, demonstrating an air temperature difference of 4.5 °C for the granite thickness of 5 cm. Granite and slag are suitable storage materials due to their superior thermal properties. The air channel height has a significant effect on the performance of the collector. The air temperature difference doubles when the channel height is reduced from 5 cm to 2 cm.