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排序方式: 共有148条查询结果,搜索用时 31 毫秒
11.
Rajapandiyan Krishnamoorthy Jegan Athinarayanan Vaiyapuri Subbarayan Periyasamy Mohammad A. Alshuniaber Ghedeir Alshammari Mohammed Jamal Hakeem Mohammed Asif Ahmed Ali A. Alshatwi 《Molecules (Basel, Switzerland)》2022,27(8)
The increase in β-lactam-resistant Gram-negative bacteria is a severe recurrent problem in the food industry for both producers and consumers. The development of nanotechnology and nanomaterial applications has transformed many features in food science. The antibacterial activity of zinc oxide nanoparticles (ZnO NPs) and their mechanism of action on β-lactam-resistant Gram-negative food pathogens, such as Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Serratia marcescens, Klebsiella pneumoniae, and Proteus mirabilis, are investigated in the present paper. The study results demonstrate that ZnO NPs possesses broad-spectrum action against these β-lactamase-producing strains. The minimal inhibitory and minimal bactericidal concentrations vary from 0.04 to 0.08 and 0.12 to 0.24 mg/mL, respectively. The ZnO NPs elevate the level of reactive oxygen species (ROS) and malondialdehyde in the bacterial cells as membrane lipid peroxidation. It has been confirmed from the transmission electron microscopy image of the treated bacterial cells that ZnO NPs diminish the permeable membrane, denature the intracellular proteins, cause DNA damage, and cause membrane leakage. Based on these findings, the action of ZnO NPs has been attributed to the fact that broad-spectrum antibacterial action against β-lactam-resistant Gram-negative food pathogens is mediated by Zn2+ ion-induced oxidative stress, actions via lipid peroxidation and membrane damage, subsequently resulting in depletion, leading to β-lactamase enzyme inhibition, intracellular protein inactivation, DNA damage, and eventually cell death. Based on the findings of the present study, ZnO NPs can be recommended as potent broad-spectrum antibacterial agents against β-lactam-resistant Gram-negative pathogenic strains. 相似文献
12.
Organoclay-modified hydroxylterminated polysulfone (PSF)/epoxy interpenetrating network nanocomposites (oM-PSF/EP nanocomposites) were prepared by adding organophilic montmorillonite (oMMT) to interpenetrating polymer networks (IPNs) of polysulfone and epoxy resin (PSF/EP) using diaminodiphenylmethane (DDM) as curing agent.The mechanical properties like tensile strength,tensile modulus,flexural strength,flexural modulus and impact properties of the nanocomposites were studied as per ASTM standards.Differ... 相似文献
13.
14.
It is pointed out that the coupling characterizing theψ-γ vertex must change substantially between the limits,ψ on mass-shell which occurs inψ→e
+
e
− and photon on mass-shell which is relevant in radiative decays likeψ→ππγ, ψ→ηγ and photoproduction ofψ. This has the consequence that the value ofψN total cross section must be larger than what is inferred from the use of naive vector dominance in photoproduction. 相似文献
15.
Subbarayan VelusamyT Punniyamurthy 《Tetrahedron letters》2003,44(50):8955-8957
Copper(II) complex 1 efficiently catalyses the oxidation of alkylbenzenes and cyclohexane into the corresponding ketones in moderate to high yields in the presence of 30% H2O2. This protocol is simple, clean and generates water as the only by-product. 相似文献
16.
17.
We point out that the equivalent-photon approximation (EPA) for processes with massive spin-1 particles in the final state would have validity in a more restricted kinematic domain
than for processes where it is commonly applied, viz., those with spin-1/2 or spin-0 particles in the final state. We obtain
the criterion for the validity ofEPA for the two-photon production of a pair of charged, massive, point-like spin-1 particlesV
±, each of massM and with a standard magnetic moment (κ=1). In a process in which one of the photons is real and the other virtual with four-momentumq, the condition for the validity ofEPA is |q
2|≪M
2, in addition to the usual condition |q
2|≪W
2,W being theV
+
V
− invariant mass. In a process in which both photons are virtual (with four-momentaq andq′), our condition is |q
2||q′2|W
4 ≪ 16M
8, in addition to |q
2| ≪M
2, |q′2| ≪M
2 and |q
2| ≪W
2, |q′2| ≪W
2. Even when these extra conditions permitting the use ofEPA are not fulfilled, convenient approximate expressions may still be obtained assuming merely |q
2| ≪W
2 and |q′2| ≪W
2.
We also discuss how the extra conditions are altered when the vector bosons are incorporated in a spontaneously broken gauge
theory. Examples ofW boson production in Weinberg-Salam model are considered for which the condition |q
2||q′2|W
4 ≪ 16M
8 is shown to be removed. 相似文献
18.
Ponnusamy Sami Kandasamy Venkateshwari Natarajan Mariselvi Arunachalam Sarathi Kasi Rajasekaran 《Transition Metal Chemistry》2010,35(2):137-142
l-cysteine undergoes facile electron transfer with heteropoly 10-tungstodivanadophosphate,
[ \textPV\textV \textV\textV \textW 1 0 \textO 4 0 ]5 - , \left[ {{\text{PV}}^{\text{V}} {\text{V}}^{\text{V}} {\text{W}}_{ 1 0} {\text{O}}_{ 4 0} } \right]^{5 - } , at ambient temperature in aqueous acid medium. The stoichiometric ratio of [cysteine]/[oxidant] is 2.0. The products of the
reaction are cystine and two electron-reduced heteropoly blue, [PVIVVIVW10O40]7−. The rates of the electron transfer reaction were measured spectrophotometrically in acetate–acetic acid buffers at 25 °C.
The orders of the reaction with respect to both [cysteine] and [oxidant] are unity, and the reaction exhibits simple second-order
kinetics at constant pH. The pH-rate profile indicates the participation of deprotonated cysteine in the reaction. The reaction
proceeds through an outer-sphere mechanism. For the dianion −SCH2CH(NH3
+)COO−, the rate constant for the cross electron transfer reaction is 96 M−1s−1 at 25 °C. The self-exchange rate constant for the
- \textSCH2 \textCH( \textNH3 + )\textCOO - \mathord