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Poly(4‐vinyl pyridine)‐grafted graphene oxide for drug delivery and antimicrobial applications 下载免费PDF全文
Graphene oxide (GO) was covalently functionalized with poly(4‐vinyl pyridine) (P4VP) by atom transfer radical polymerization for drug delivery and antimicrobial applications. The physiochemical properties, chemical structure, composition and morphology of the P4VP‐functionalized GO (GO‐P4VP) were studied. Simple physisorption of a cancer drug, camptothecin (CPT), via π ? π stacking and/or hydrophobic interactions on the GO‐P4VP was tested for drug loading and its release by altering the pH. The GO‐P4VP has low cytotoxicity, and the CPT‐loaded GO‐P4VP exhibited a high potency for killing cancer cells in vitro. Prominent antimicrobial properties against Escherichia coli and Staphylococcus aureus were also observed. Thus, the GO‐P4VP can be utilized as a drug delivery vector with high biocompatibility, solubility and stability in physiological solutions, a suitable payload capacity and excellent bacterial toxicity. Owing to its small size, low cost, large specific area, ready scalability and useful non‐covalent interactions, GO‐P4VP is a novel material for biomedical, industrial and environmental applications. © 2015 Society of Chemical Industry 相似文献
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This paper presents an optimal control strategy using linear quadratic regulator (LQR) applied in current-controlled voltage source inverter (CCVSI) to control the real and reactive power flow between the renewable energy system (RES) and the grid. It also compensates harmonic current components drawn by the load from the grid terminal. A simplified equivalent circuit is used to develop the reduced order state space model of the three-phase grid connected renewable energy system. This makes the analysis and design of control law simpler by reducing the number of weighing variables used in LQR. The extension real–reactive power (p–q) method implemented in a–b–c frame is used to generate the reference current for controlling the real and reactive power to the grid to minimize the total harmonic distortion (THD) and to achieve unity power factor (UPF) operation at the grid side. The stated technique makes the grid current sinusoidal even under unbalanced grid voltages and the harmonic distortion factors are well within the IEEE limits. The system is simulated under changes in the real power fed from RES to the grid for both balanced and unbalanced grid conditions. The simulation results are validated by the experimental results. 相似文献
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Nur Fatihah Mohd Yatim Masitah Abd. Rahim Kavitha Menon Faisal Muti Al-Hassan Rahimah Ahmad Anita Bhajan Manocha Mohamed Saleem Badrul Hisham Yahaya 《International journal of molecular sciences》2014,15(5):8835-8845
Both α- and β-thalassaemia syndromes are public health problems in the multi-ethnic population of Malaysia. To molecularly characterise the α- and β-thalassaemia deletions and mutations among Malays from Penang, Gap-PCR and multiplexed amplification refractory mutation systems were used to study 13 α-thalassaemia determinants and 20 β-thalassaemia mutations in 28 and 40 unrelated Malays, respectively. Four α-thalassaemia deletions and mutations were demonstrated. −−SEA deletion and αCSα accounted for more than 70% of the α-thalassaemia alleles. Out of the 20 β-thalassaemia alleles studied, nine different β-thalassaemia mutations were identified of which βE accounted for more than 40%. We concluded that the highest prevalence of (α- and β-thalassaemia alleles in the Malays from Penang are −−SEA deletion and βE mutation, respectively. 相似文献
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Methacrylate based copolymers are considered as one of the best organic coating materials for anticorrosive application. Poly(N-vinyl carbazole-co-glycidyl methacrylate) have been synthesized by free radical solution polymerization technique from different mole ratios of N-vinyl carbazole (N-Vc) and glycidyl methacrylate (GMA) and characterized using Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (1H NMR and 13C NMR). Thermal analyses of the poly(N-Vc-co-GMA) were performed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The number average molecular weight (Mn) of different compositions of the same was determined by gel permeation chromatography (GPC). The corrosion performances of low nickel stainless steel specimens coated with different composition of copolymers were investigated in 1 M H2SO4 using potentiodynamic polarization, electrochemical impedance spectroscopic (EIS) method, scanning electron microscopic (SEM) and energy dispersive X-ray analysis (EDAX). Poly(N-Vc-co-GMA) have been provided in order to achieve adherent, low permeability to aggressive ions as well as environmentally favored good anticorrosive coating. Electrochemical corrosion test and surface analysis results clearly showed that poly(N-Vc-co-GMA) coatings served as a stable host matrix on low nickel stainless steel against corrosion. It was also observed that the coatings of poly(N-Vc-co-GMA) with equal mole ratio of N-Vc and GMA exhibited the best corrosion resistance among all combinations. 相似文献
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Sulfur ion (S6+) was doped into the anatase TiO2 prepared by sol–gel method (SG-TiO2) using sulfur powder as a sulfur source (S-TiO2) and its photoreactivity was probed for the degradation of phenol under UV/solar light illumination. The S-TiO2 and SG-TiO2 were characterized by PXRD, UV–vis DRS, FTIR, SEM, XPS, BET and PL techniques. It was observed that S6+ ion was incorporated into the TiO2 crystal lattice at Ti4+ lattice site and the sulfur on the surface gets modified to 4SO2− due to the heat treatment under atmospheric conditions. The high photocatalytic activity of S-TiO2 compared to SG-TiO2 is attributed to the surface modification of sulfur as sulfate which plays a crucial role in trapping electrons. S-TiO2 shows significant increase in the surface area, reduced crystallite size, increased surface acidity, visible light absorption and prolonged lifetime of the photogenerated charge carriers. Hole scavengers like potassium iodide and tertiary butanol suggested the surface degradation mechanism rather than the bulk degradation pathway. Addition of oxidizing agents to the degradation reaction did not show any enhancement in the degradation rates since the presence of 4SO2− on the TiO2 surface itself acts as the efficient electron trapping centers. Both trapping and detrapping of the electron takes place more efficiently at 4SO2− centers. The enhanced activity of S-TiO2 is attributed to the synergistic effect between S6+ dopant with surface modified 4SO2−. 相似文献
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A modified shortest path network interdiction model is approximated in this work by a constrained binary knapsack which uses aggregated arc maximum flow as the objective function coefficient. In the modified shortest path network interdiction problem, an attacker selects a path of highest non-detection probability on a network with multiple origins and multiple available targets. A defender allocates a limited number of resources within the geographic region of the network to reduce the maximum network non-detection probability between all origin-target pairs by reducing arc non-detection probabilities and where path non-detection probability is modeled as a product of all arc non-detection probabilities on that path. Traditional decomposition methods to solve the shortest path network interdiction problem are sensitive to problem size and network/regional complexity. The goal of this paper is to develop a method for approximating the regional allocation of defense resources that maintains accuracy while reducing both computational effort and the sensitivity of computation time to network/regional properties. Statistical and spatial analysis methods are utilized to verify approximation performance of the knapsack method in two real-world networks. 相似文献
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This investigation reports the preparation of styrene–α‐olefinic random copolymers, using 1‐octene as an α‐olefin, via atom transfer radical polymerization. Atom transfer radical copolymerization of styrene with 1‐octene was successfully carried out using phenylethyl bromide as initiator and CuBr as catalyst in combination with N, N, N′, N″, N″‐pentamethyldiethylenetriamine as ligand. The copolymers had controlled molecular weight, narrow dispersity and well‐defined end groups with significant 1‐octene incorporation in the polymer. Incorporation of 1‐octene in the copolymers was confirmed using 1H NMR and matrix‐assisted laser desorption ionization time‐of‐flight mass spectroscopy. An increase in 1‐octene content in the monomer feed led to an increase in the level of incorporation of the α‐olefin in the copolymer. An increase in the concentration of 1‐octene led to a decrease in the rate of polymerization and an increase in dispersity. The glass transition temperature of the copolymer gradually decreased as the incorporation of 1‐octene increased. Copyright © 2011 Society of Chemical Industry 相似文献
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Jit Biswas Andrei Tolstikov Maniyeri Jayachandran Victor Foo Aung Aung Phyo Wai Clifton Phua Weimin Huang Louis Shue Kavitha Gopalakrishnan Jer-En Lee Philip Yap 《电信纪事》2010,65(9-10):505-521
Monitoring and timely intervention are extremely important in the continuous management of health and wellness among all segments of the population, but particularly among those with mild dementia. In relation to this, we prescribe three design principles for the construction of services and applications. These are ambient intelligence, service continuity, and micro-context. In this paper, we provide three exemplars from our research and development activities that illustrate the use of these design principles in the construction of services and applications. All the applications are drawn from the field of care for mild dementia patients in their living quarters. 相似文献