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111.
Hemalatha Murugaiah Chow Lun Teh Kai Chew Loh Ahmad Ramli Mohamad Yahya Nur Asshifa Md Noh Noor Hana Hanif Abu Bakar Daruliza Kernain Rokiah Hashim Yazmin Bustami 《Molecules (Basel, Switzerland)》2021,26(21)
Here, we report the extracellular biosynthesis of silver nanoparticles (AgNPs) and determination of their antibacterial and anticancer properties. We also explore the efficacy of bioAgNPs incorporated in cellulose nanocrystals (CNCs) and alginate (Alg) for the formation of an antibacterial hydrogel film. Streptomyces sp. PBD-311B was used for the biosynthesis of AgNPs. The synthesized bioAgNPs were characterized using UV-Vis spectroscopy, TEM, XRD, and FTIR analysis. Then, the bioAgNPs’ antibacterial and anticancer properties were determined using TEMA and cytotoxicity analysis. To form the antibacterial hydrogel film, bioAgNPs were mixed with a CNC and Alg solution and further characterized using FTIR analysis and a disc diffusion test. The average size of the synthesized bioAgNPs is around 69 ± 2 nm with a spherical shape. XRD analysis confirmed the formation of silver nanocrystals. FTIR analysis showed the presence of protein capping at the bioAgNP surface and could be attributed to the extracellular protein binding to bioAgNPs. The MIC value of bioAgNPs against P. aeruginosa USM-AR2 and MRSA was 6.25 mg/mL and 3.13 mg/mL, respectively. In addition, the bioAgNPs displayed cytotoxicity effects against cancer cells (DBTRG-0.5MG and MCF-7) and showed minimal effects against normal cells (SVG-p12 and MCF-10A), conferring selective toxicity. Interestingly, the bioAgNPs still exhibited inhibition activity when incorporated into CNC/Alg, which implies that the hydrogel film has antibacterial properties. It was also found that bioAgNP-CNC/Alg displayed a minimal or slow release of bioAgNPs owing to the intermolecular interaction and the hydrogel’s properties. Overall, bioAgNP-CNC/Alg is a promising antibacterial hydrogel film that showed inhibition against the pathogenic bacteria P. aeruginosa and MRSA and its application can be further evaluated for the inhibition of cancer cells. It showed benefits for surgical resection of a tumor to avoid post-operative wound infection and tumor recurrence at the surgical site. 相似文献
112.
Electronic absorption spectra of some nicotinamides and nicotinic acids. Molecular orbital treatment
R. H. Abu Eittah M. M. Hamed A. A. Mohamed 《International journal of quantum chemistry》1997,64(6):689-701
The electronic absorption spectra of the position isomers nicotinamide and isonicotinamide, nicotinic acid, and isonicotinic acid were investigated, together with the spectra of thionicotinamide, N-methyl nicotinamide and nicotinic acid N oxide. Apparent differences in the spectra of the position isomers were interpreted in terms of the torsion angle between the planes of the molecule, the height of the barrier to internal rotation, and the results of molecular orbital (MO) calculations. The largest perturbation effect was observed in the case of thionicotinamide whereas the smallest effect was observed in the case of nicotinic acid N oxide. MO calculations have indicated the existence of overlapping transitions. The observed transitions proved to be π-π* transitions, none of the n-π* was observed. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 64 : 689–701, 1997 相似文献
113.
This study is to investigate the magnetohydrodynamic (MHD) stagnation point flow and heat transfer characteristic nanofluid of carbon nanotube (CNTs) over the shrinking surface with heat sink effects. Similarity equations deduced from momentum and energy equation of partial differential equations are solved numerically. This study looks at the different parameters of the flow and heat transfer using first phase model which is Tiwari-Das. The parameter discussed were volume fraction nanoparticle, magnetic parameter, heat sink/source parameters, and a different type of nanofluid and based fluids. Present results revealed that the rate of nanofluid (SWCNT/kerosene) in terms of flow and heat transfer is better than (MWCNT/kerosene) and (CNT/water) and regular fluid (water). Graphically, the variation results of dual solution exist for shrinking parameter in range for different values of volume fraction nanoparticle, magnetic, heat sink parameters, and a different type of nanofluid. However, a unique solution exists at , and no solutions exist at which is a critical value. In addition, the local Nusselt number decreases with increasing volume fraction nanoparticle when there exists a heat sink effect. The values of the skin friction coefficient and local Nusselt number increase for both solutions with the increase in magnetic parameter. In this study, the investigation on the flow and heat transfer of MHD stagnation point nanofluid through a shrinking surface with heat sink effect shows how important the application to industrial applications. 相似文献
114.
Khaled A. Selim Salman S. Alharthi Abdelmonam M. Abu El-Hassan Nady A. Elneairy Laila A. Rabee Adel G. Abdel-Razek 《Molecules (Basel, Switzerland)》2021,26(20)
Fish oil is the primary source of long-chain omega-3 fatty acids, which are important nutrients that assist in the prevention and treatment of heart disease and have many health benefits. It also contains vitamins that are lipid-soluble, such as vitamins A and D. This work aimed to determine how the wall material composition influenced the encapsulation efficiency and oxidative stability of omega fish oils in spray-dried microcapsules. In this study, mackerel, sardine waste oil, and sand smelt fish oil were encapsulated in three different wall materials (whey protein, gum Arabic (AG), and maltodextrin) by conventional spray-drying. The effect of the different wall materials on the encapsulation efficiency (EE), flowability, and oxidative stability of encapsulated oils during storage at 4 °C was investigated. All three encapsulating agents provided a highly protective effect against the oxidative deterioration of the encapsulated oils. Whey protein was found to be the most effective encapsulated agent comparing to gum Arabic and maltodextrin. The results indicated that whey protein recorded the highest encapsulation efficiency compared to the gum Arabic and maltodextrin in all encapsulated samples with EE of 71.71%, 68.61%, and 64.71% for sand smelt, mackerel, and sardine oil, respectively. Unencapsulated fish oil samples (control) recorded peroxide values (PV) of 33.19, 40.64, and 47.76 meq/kg oil for sand smelt, mackerel, and sardine oils after 35 days of storage, while all the encapsulated samples showed PV less than 10 in the same storage period. It could be concluded that all the encapsulating agents provided a protective effect to the encapsulated fish oil and elongated the shelf life of it comparing to the untreated oil sample (control). The results suggest that encapsulation of fish oil is beneficial for its oxidative stability and its uses in the production of functional foods. 相似文献
115.
The effect of quantum well number on the quantum efficiency and temperature characteristics of In- GaN/GaN laser diodes (LDs) is determined and investigated. The 3-nm-thick In0.13Ca0.87N wells and two 6-am-thick GaN barriers are selected as an active region for Fabry-Perot (FP) cavity waveguide edge emitting LD. The internal quantum efficiency and internal optical loss coefficient are extracted through the simulation software for single, double, and triple InGaN/GaN quantum wells. The effects of device temperature on the laser threshold current, external differential quantum efficiency (DQE), and output wavelength are also investigated. The external quantum efficiency and characteristic temperature are improved significantly when the quantum well number is two. It is indicated that the laser structures with many quantum wells will suffer from the inhomogeneity of the carrier density within the quantum well itself which affects the LD performance. 相似文献
116.
A surface wave in a planar nonlinear waveguide is a current problem that has several applications in modern electronics and optics such as optical sensors design. The effect of thermal stress on the optical performance of a nonlinear symmetrical sensor is studied. The mathematical forms of the dispersion equation and thermal-stress sensitivity are analytically derived and plotted numerically. It is found that the thermal sensitivity of the sensor can be controlled by tuning the core size, by changing the loading materials, and by carefully selecting the materials. 相似文献
117.
Photoluminescence properties of thenardite activated with Eu 总被引:1,自引:0,他引:1
Aierken Sidike Rahman Abu Zayed Mohammad Saliqur Jui-Yang He K. Atobe N. Yamashita 《Journal of luminescence》2009,129(11):1271-1275
Na2SO4:Eu phosphors were prepared by heating pure natural thenardite with EuF3 at 900 °C for 20 min in air. The photoluminescence (PL) and excitation spectra of as-prepared and γ-ray-irradiated phosphors were observed at 300 K. The PL spectrum under 394 nm excitation consisted of strong narrow bands with peaks at 579, 592, 616, 652, 697 and 741 nm, assigned to the 5D0→7FJ (J=0, 1, 2, …, 5) transitions, respectively, within Eu3+. The PL spectrum under 340 nm excitation consisted of a broad Eu2+ band with a peak at 435 nm. The excitation spectrum obtained by monitoring the violet luminescence consisted of a weak band with a peak at approximately 261 nm and a broad Eu2+ band with a peak at approximately 338 nm. The relative efficiency of the violet luminescence of the γ-ray-irradiated phosphor at the exposure of 46 kGy increased up to 3.0 times that of the unirradiated phosphor. The enhancement of violet luminescence by γ-ray irradiation was ascribed to the conversion of Eu3+ to Eu2+ in Na2SO4. 相似文献
118.
Mohd Basyaruddin Abdul Rahman Naz Chaibakhsh Mahiran Basri Abu Bakar Salleh Raja Noor Zaliha Raja Abdul Rahman 《Applied biochemistry and biotechnology》2009,158(3):722-735
In this study, an artificial neural network (ANN) trained by backpropagation algorithm, Levenberg–Marquadart, was applied
to predict the yield of enzymatic synthesis of dioctyl adipate. Immobilized Candida antarctica lipase B was used as a biocatalyst for the reaction. Temperature, time, amount of enzyme, and substrate molar ratio were
the four input variables. After evaluating various ANN configurations, the best network was composed of seven hidden nodes
using a hyperbolic tangent sigmoid transfer function. The correlation coefficient (R
2) and mean absolute error (MAE) values between the actual and predicted responses were determined as 0.9998 and 0.0966 for
training set and 0.9241 and 1.9439 for validating dataset. A simulation test with a testing dataset showed that the MAE was
low and R
2 was close to 1. These results imply the good generalization of the developed model and its capability to predict the reaction
yield. Comparison of the performance of radial basis network with the developed models showed that radial basis function was
more accurate but its performance was poor when tested with unseen data. In further part of the study, the feedforward backpropagation
model was used for prediction of the ester yield within the given range of the main parameters. 相似文献
119.
Corticosteroids and related compounds containing the 20-keto-21-hydroxyl side chain such as betamethasone, betamethasone 9,11-epoxide, dexamethasone, and dexamethasone 9,11-epoxide have been found to undergo facile autooxidation on the 1,3-dihydroxyacetone side chain of their D-rings under strong alkaline conditions to yield five main degradants (17-formyloxy-17-acid, 17-acid, 21-aldehyde, 20-hydroxy-21-acid, and 17-ketone). The rate of the autooxidation was correlated with the strength and concentration of the base used in the reaction. A novel mechanism for the observed autooxidation is proposed, in which the facile oxidation of the presumed enolate (resulting from the carbanion at the 21-position) by molecular oxygen is the key step. The proposed autooxidation mechanism, supported by LC-MS isotope experiments using 18O2 as the oxidant, can satisfactorily explain the oxidative degradation patterns observed for corticosteroids containing the 20-keto-21-hydroxyl side chain. 相似文献
120.
Ethylene propylene diene monomer grafted with maleic ahydride (MAH-g-EPDM) was prepared by peroxide-initiated melt grafting of MAH onto EPDM using a HAAKE internal mixer at 180 °C and 60 rpm for 5 min. The effect of MAH-g-EPDM compatibilizer on the interactions, and tensile and morphological properties of halloysite nanotubes (HNTs) filled EPDM nanocomposites was investigated. The tensile properties of the nanocomposites were influenced by two major factors. The hydrogen bonding between MAH-g-EPDM and HNTs, which was confirmed by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), as well as the formation of EPDM-rich and HNT-rich areas, are the dominant effects on the tensile strength of the nanocomposites at low and high HNT loading, respectively. It was found that the cure time (t90), maximum torque (MH) and minimum torque (ML) of the compatibilized nanocomposites were increased after adding MAH-g-EPDM. The reinforcement mechanism of the compatibilized and un-compatibilized EPDM/HNT nanocomposites was also investigated based on morphological observations of the nanocomposites. 相似文献