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排序方式: 共有275条查询结果,搜索用时 10 毫秒
81.
Nur Shuhaidatul Sarmiza Abdul Halim Kamal Shaik Fakiruddin Syed Atif Ali Badrul Hisham Yahaya 《International journal of molecular sciences》2014,15(9):15044-15060
Mesenchymal stem cells (MSCs) hold tremendous potential for therapeutic use in stem cell-based gene therapy. Ex vivo genetic modification of MSCs with beneficial genes of interest is a prerequisite for successful use of stem cell-based therapeutic applications. However, genetic manipulation of MSCs is challenging because they are resistant to commonly used methods to introduce exogenous DNA or RNA. Herein we compared the effectiveness of several techniques (classic calcium phosphate precipitation, cationic polymer, and standard electroporation) with that of microporation technology to introduce the plasmid encoding for angiopoietin-1 (ANGPT-1) and enhanced green fluorescent protein (eGFP) into human adipose-derived MSCs (hAD-MSCs). The microporation technique had a higher transfection efficiency, with up to 50% of the viable hAD-MSCs being transfected, compared to the other transfection techniques, for which less than 1% of cells were positive for eGFP expression following transfection. The capability of cells to proliferate and differentiate into three major lineages (chondrocytes, adipocytes, and osteocytes) was found to be independent of the technique used for transfection. These results show that the microporation technique is superior to the others in terms of its ability to transfect hAD-MSCs without affecting their proliferation and differentiation capabilities. Therefore, this study provides a foundation for the selection of techniques when using ex vivo gene manipulation for cell-based gene therapy with MSCs as the vehicle for gene delivery. 相似文献
82.
Nor Ain Shahera Khairi Nor Azah Yusof Abdul Halim Abdullah Faruq Mohammad 《International journal of molecular sciences》2015,16(5):10562-10577
In recent years, molecularly-imprinted polymers (MIPs) have attracted the attention of several researchers due to their capability for molecular recognition, easiness of preparation, stability and cost-effective production. By taking advantage of these facts, Hg(II) imprinted and non-imprinted copolymers were prepared by polymerizing mercury nitrate stock solution (or without it) with methacrylic acid (MAA), 2-hydroxyl ethyl methacrylate (HEMA), methanol and ethylene glycol dimethacrylate (EGDMA) as the monomer, co-monomer solvent (porogen) and cross-linker, respectively. Thus, the formed Hg(II) imprinted polymer was characterized by using Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), Brunauer, Emmett and Teller (BET) and thermal gravimetric analysis (TGA). The separation and preconcentration characteristics of Hg(II) imprinted polymer were investigated by solid phase extraction (SPE) procedures, and an optimal pH of 7 was investigated as ideal. The specific surface area of the Hg(II) imprinted polymer was found to be 19.45 m2/g with a size range from 100 to 140 µm in diameter. The maximum adsorption capacity was observed to be 1.11 mg/g of Hg(II) imprinted beads with 87.54% removal of Hg(II) ions within the first 5 min. The results of the study therefore confirm that the Hg(II) imprinted polymer can be used multiple times without significantly losing its adsorption capacity. 相似文献
83.
S. A. Halim Al-Khawaldeh Saleh H. Azhan S. B. Mohamed K. Khalid J. Suradi 《Journal of Materials Science》2000,35(12):3043-3046
Sol-gel method have been used to convert metal carbonates, oxides andnitrates into corresponding acetate precursors for gel formation.About 90% volume of high T
C superconducting phase (2223)has been obtained for oxide-carbonate system. This value iscomparable to that obtained from pure acetates (91% volume).However, the nitrates-'derived sample has a high-T
Cphase of 88% due to poor conversion of nitrates to acetates asobserved by the infrared spectra. The dominance of high-T
Cphase was observed in all systems as evidenced in the single steptransition of R-T curves. Hence the percentage of thehigh-TC phase dictates the value of T
C(R = 0)as 104 K, 103 K and 99 K, for oxide-carbonate, pure metal acetatesand nitrates system respectively. 相似文献
84.
Halim Benhabiles Jean-Philippe Vandeborre Guillaume Lavoué Mohamed Daoudi 《The Visual computer》2010,26(12):1451-1466
In this paper, we present an extensive experimental comparison of existing similarity metrics addressing the quality assessment
problem of mesh segmentation. We introduce a new metric, named the 3D Normalized Probabilistic Rand Index (3D-NPRI), which
outperforms the others in terms of properties and discriminative power. This comparative study includes a subjective experiment
with human observers and is based on a corpus of manually segmented models. This corpus is an improved version of our previous
one (Benhabiles et al. in IEEE International Conference on Shape Modeling and Application (SMI), 2009). It is composed of a set of 3D-mesh models grouped in different classes associated with several manual ground-truth segmentations.
Finally the 3D-NPRI is applied to evaluate six recent segmentation algorithms using our corpus and the Chen et al.’s (ACM
Trans. Graph. (SIGGRAPH), 28(3), 2009) corpus. 相似文献
85.
Ahmad Saudi Samosir Abdul Halim Mohd Yatim 《Simulation Modelling Practice and Theory》2010,18(5):663-676
This paper proposes a new control technique for synchronous buck DC–DC converter. Theory, design and implementation of the proposed control technique are provided. A new approach for converter controller synthesis based on dynamic evolution control theory is presented. In order to synthesize the converter controller, this method uses a simple analysis of nonlinear equation models of the converter. The synthesis process is simple and requires a quite low bandwidth for the controller. Therefore, this control method is suitable for digital control implementation. As an illustrative example, the synthesis of synchronous buck DC–DC converter controller is discussed in detail. The model of the synchronous buck DC–DC converter system was implemented using SimPowerSystems toolbox of MATLAB-SIMULINK. Performance of the proposed dynamic evolution control under step load change and step input voltage condition was investigated. Simulation results confirm that the proposed control method is superior to traditional PI based controller because of fast transient response and good disturbance rejection. 相似文献
86.
Ruth Naomi Muhammad Dain Yazid Hasnah Bahari Yong Yoke Keong Retnagowri Rajandram Hashim Embong Soo Huat Teoh Shariff Halim Fezah Othman 《International journal of molecular sciences》2022,23(6)
BPA is one of the most common endocrine disruptors that is widely being manufactured daily nationwide. Although scientific evidence supports claims of negative effects of BPA on humans, there is also evidence suggesting that a low level of BPA is safe. However, numerous in vivo trials contraindicate with this claim and there is a high possibility of BPA exposure could lead to obesity. It has been speculated that this does not stop with the exposed subjects only, but may also cause transgenerational effects. Direct disruption of endocrine regulation, neuroimmune and signaling pathways, as well as gut microbiata, has been identified to be interrupted by BPA exposure, leading to overweight or obesity. In these instances, cardiovascular complications are one of the primary notable clinical signs. In regard to this claim, this review paper discusses the role of BPA on obesity in the perspective of endocrine disruptions and possible cardiovascular complications that may arise due to BPA. Thus, the aim of this review is to outline the changes in gut microbiota and neuroimmune or signaling mechanisms involved in obesity in relation to BPA. To identify potentially relevant articles, a depth search was done on the databases Nature, PubMed, Wiley Online Library, and Medline & Ovid from the past 5 years. According to Boolean operator guideline, selected keywords such as (1) BPA OR environmental chemical AND fat OR LDL OR obese AND transgenerational effects or phenocopy (2) Endocrine disruptors OR chemical AND lipodystrophy AND phenocopy (3) Lipid profile OR weight changes AND cardiovascular effect (4) BPA AND neuroimmune OR gene signaling, were used as search terms. Upon screening, 11 articles were finalized to be further reviewed and data extraction tables containing information on (1) the type of animal model (2) duration and dosage of BPA exposure (3) changes in the lipid profile or weight (4) genes, signaling mechanism, or any neuroimmune signal involved, and (5) transgenerational effects were created. In toto, the study indicates there are high chances of BPA exposure affecting lipid profile and gene associated with lipolysis, leading to obesity. Therefore, this scoping review recapitulates the possible effects of BPA that may lead to obesity with the evidence of current in vivo trials. The biomarkers, safety concerns, recommended dosage, and the impact of COVID-19 on BPA are also briefly described. 相似文献
87.
Mohd Rodhi Sahid Abdul Halim Mohd Yatim 《Simulation Modelling Practice and Theory》2011,19(2):599-611
A new Bridgeless PFC circuit based on Single-Ended Primary Inductance Converter (SEPIC) is proposed in this paper. The new topology has less component count and less conducted component during each mode of operation within one switching period. The small-signal and steady-state model of the circuit operated in Discontinuous Conduction Mode (DCM) is derived using the Current Injected Equivalent Circuit Approach (CIECA). The large-signal model based on state-space and switch model are also developed to verify the large-signal behavior. The simulation results of the proposed converter show that the output voltage of the proposed converter is successfully regulated to its desired value while the input current regulation is inherent. 相似文献
88.
Ahmed Hafaifa Ferhat Laaouad Kouider Laroussi 《International Journal of Control, Automation and Systems》2011,9(1):69-79
Fuzzy control is a practical alternative for a variety of challenging control applications since it provides a convenient method for constructing nonlinear controllers via the use of heuristic information. This approach provides a formal methodology for representing, manipulating, and implementing a human’s heuristic knowledge about how to modeled and to control a system. This paper focuses on the application of fuzzy control approach to the surge phenomena in centrifugal compression system. Fuzzy controller is designed to consist of an active surge control and phase control without any explicit system models, but driven in the human thinking mechanism. This fuzzy control methodology suggested in this work reproduced well the main characteristics of the turbo compressor dynamic model developed by Moore and Gretzer and give place to a more precise and easy to handle representation. Application and simulation results are performed to demonstrate the effectiveness of this controller. Studies show that, the proposed controller provides good tracking control performance for the compression system at different operating conditions and moreover improves the dynamic performances of the system. 相似文献
89.
Nurul Mu azzah Abdul Latiff NikNoordini NikAbdMalik Abdul Halim Abdul Latiff 《电子科技学刊:英文版》2016,14(2):160-169
Energy consumption of sensor nodes is one of the crucial issues in prolonging the lifetime of wireless sensor networks. One of the methods that can improve the utilization of sensor nodes batteries is the clustering method. In this paper, we propose a green clustering protocol for mobile sensor networks using particle swarm optimization (PSO) algorithm. We define a new fitness function that can optimize the energy consumption of the whole network and minimize the relative distance between cluster heads and their respective member nodes. We also take into account the mobility factor when defining the cluster membership, so that the sensor nodes can join the cluster that has the similar mobility pattern. The performance of the proposed protocol is compared with well-known clustering protocols developed for wireless sensor networks such as LEACH (low-energy adaptive clustering hierarchy) and protocols designed for sensor networks with mobile nodes called CM-IR (clustering mobility-invalid round). In addition, we also modify the improved version of LEACH called MLEACH-C, so that it is applicable to the mobile sensor nodes environment. Simulation results demonstrate that the proposed protocol using PSO algorithm can improve the energy consumption of the network, achieve better network lifetime, and increase the data delivered at the base station. 相似文献
90.
Mohammad Nahid Siddiqui Halim Hamid Redhwi Muhammad Younas Syed Hussain Dimitrios S. Achilias 《Petroleum Science and Technology》2018,36(11):756-764
Asphaltene filled LDPE composite were prepared and characterized. The composites were studied to determine the reinforcement imparted by the asphaltene on the durability of LDPE polymer. The study showed that the composites have higher melting and crystalline behavior, delays the degradation induced by heat and acts as a thermal barrier limiting the emission of the gaseous degradation products, resulting in an increase in the thermal stability of the composites, higher tensile strength, have higher values of the storage and loss modulus. 5 wt% of asphaltenes added in the LDPE afforded the best dispersion in the polymeric matrix, larger crystallite size, enhanced thermal stability, highest relative degree of crystallinity and improved mechanical tensile or thermo-mechanical properties. 相似文献