Influence Of Metal Nanoparticles Research Articles

Influence of support polarity on the selective hydrogenation of nitrostyrene over Pt-based heterogenous catalysts

Enhancing the selectivity of noble metal containing heterogeneous catalysts in the nitro group hydrogenation of functionalized nitroarenes is challenging due to high dependence of selectivity on the catalyst structure. Most reports focus on the influence of metal nanoparticles (NPs) size, confinement, and support-metal interactions, while the effect of support polarity remains unclear. Herein we investigate, for the first time, the influence of support polarity on the selective hydrogenation of NO2 in 3-nitrostyrene over Pt-based heterogeneous catalysts and compare it to the effects of Pt NPs size and location. To achieve this, we confined Pt NPs in the channels of the nonpolar Silicalite-1 (S-1) and benchmarked against catalysts with NPs of various sizes supported on polar SiO2 and nonpolar S-1.We demonstrate that support polarity is the key factor determining selectivity, surpassing the roles of Pt particle size and confinement. Catalysts with the nonpolar Silicalite-1 support exhibit higher NO2 selectivity compared to SiO2-based ones, with a threefold increase observed for Pt@S–S-1 compared to a commercial Pt/SiO2. DRIFT spectroscopy-monitored adsorption experiments and hydrogenation experiments of nitrobenzene and styrene model molecules show that the S-1 support favors the adsorption of –NO2 and the –NH2 formed during the reaction, impeding C=C hydrogenation. To a lower extent, the size of Pt NPs contributed to the obtained results with decreased C=C hydrogenation observed over smaller Pt NPs. Finally, confining Pt in the zeolite restricts the NPs growth during catalyst activation, resulting in a further decrease of particles size and C=C hydrogenation activity.

The influence of metal nanoparticles on plants

The influence of metal nanoparticles on plants

Cellular markers of chronic obstructive pulmonary disease from exposure to nanoparticlecontaining aerosols

Introduction. The role of industrial aerosol nanoparticles in the development of chronic obstructive pulmonary disease is still poorly understood. The aim of study is to determine the distribution of monocyte subpopulations in patients with chronic obstructive pulmonary disease under the influence of industrial aerosols containing nanoparticles. Materials and methods. A single-center cohort observational study included patients with chronic obstructive pulmonary disease (COPD) (GOLD 2011 criteria) who were exposed to industrial aerosols (n=32), COPD patients, tobacco smokers (n=35), and conditionally healthy individuals without occupational hazards (n=29). Nanoparticles in the air of the working area were determined by inductively coupled plasma atomic emission spectrometry and scanning electron microscopy. Metal-containing nanoparticles (Pb, Fe, Cr) predominated in the casters' workplaces, while the grinders were mainly exposed to silicon dioxide nanoparticles. The groups were comparable by gender, age, and duration of COPD. Monocyte subpopulations in peripheral blood were determined by flow cytofluorometry. Results. In COPD patients who worked in contact with an industrial aerosol containing metal nanoparticles, the proportion of "classical" CD14+CD16- monocytes was increased, and the proportion of "intermediate" CD14+CD16+ and "non-classical" CD14dimCD16+ was reduced. The percentage of "non-classical" monocytes exposed to silicon dioxide nanoparticles was increased, and the percentage of "intermediate" monocytes was reduced. At the same time, the proportion of classical monocytes was highest in patients with COPD who worked under the influence of metal nanoparticles (84.3%±6.3%), intermediate monocytes - in patients with COPD due to tobacco smoking (6.1%±1.5%), non-classical monocytes - in the group of COPD and contact with silicon dioxide nanoparticles (20.45%±0.25%). Conclusions. COPD under the influence of industrial aerosol containing metal nanoparticles is characterized by an increase in the proportion of "classical' monocytes, and silicon dioxide nanoparticles - "non-classical”. The level of subpopulations of blood monocytes is a promising marker of professionally caused COPD.

Effect of metal nanoparticles on the accumulation and structure of rapeseed carbohydrates

The purpose was to conduct field tests of the most active metal nanoparticles of iron, cobalt and copper to realize the maximum accumulation of polysaccharides in plants; to develop a method for obtaining and studying the structure of polysaccharides obtained from plants treated before sowing with metal nanoparticles; to study the physical-chemical characteristics of polysaccharides and the monosaccharide composition under the influence of metal nanoparticles. Before sowing, seed treatment was carried out with suspensions of nanoparticles with a concentration of 0.5 g/ha (hectare seed sowing rate). Observed under the influence of copper nanoparticles, the yield increased by 15 % comparison to the control one. When determining the monosaccharide composition, in addition to changing the quantitative content of monosaccharides, a high concentration of galacturonic acid was observed, especially when treating seeds with copper nanoparticles before sowing.

Modification of Anaerobic Sealants by Metal Nanoparticles

The choice of metal nanoparticles in the filling of anaerobic sealants is theoretically justified. The influence of metal nanoparticles on the polymerization process, as well as on the improvement of strength, endurance and heat conductivity of anaerobic sealant nanocomposites is described, as well.

The Influence of Metal Nanoparticles on the Propagation of Extremely Short Optical Pulses in Graphene

The propagation of two-dimensional extremely short optical pulses in graphene with metal nanoparticles has been investigated. The effects that are observed when changing the parameters of the effective Hamiltonian, which takes into account the exchange interaction, have been studied. It has been revealed that the introduction of metallic adatoms into graphene leads to an increase in the amplitude of the pulse. This effect can be enhanced by choosing a particular metal particle .

Analysis of polariton dispersion in metal nanocomposite based novel superlattice system

Abstract The influence of metal nanoparticles in tuning the polaritonic gap in a novel piezoelectric superlattice is studied. Dielectric function of the metal nanoparticles is analyzed using Kawabata-Kubo effect and Drude’s theory. The effective dielectric function of the nanocomposite system is studied using Maxwell Garnett approximation. Nanocomposite based LiTaO 3 novel superlattice is formed by arranging the nanocomposite systems in such a way that their orientations are in the opposite direction. Hence there are two additional modes of propagation. The top most modes reflect the metal behavior of the nanoparticles. It is found that these modes of propagation vary with the filling factor. These additional modes of propagations can be exploited in the field of communication.

Влияние наночастиц металла на механические характеристики композитных материалов

Влияние наночастиц металла на механические характеристики композитных материалов

Enhanced Nonlinear Optical Response of Resonantly Coupled Silver Nanoparticle–Organic Dye Complexes

The influence of metal nanoparticles on linear and nonlinear optical properties of surrounding organic molecules has been widely investigated, whereas much less attention has been paid to the influence of molecules on properties of nanoparticles. Here, we employ transient absorption spectroscopy to address the nonlinear optical responses of the resonantly coupled silver nanoparticle–organic dye systems and demonstrate that silver nanoparticles covered with dye molecules show enhanced and spectrally different nonlinear extinction changes from pristine nanoparticles. We identify changes of the plasmon resonance band of nanoparticles induced by excitation of surrounding dye. We attribute these exciton–plasmon coupling effects to the excitation-induced refractive index modifications of the dye layer surrounding a nanoparticle and to the back-transfer of the oscillator strength borrowed by the dye from the nanoparticle.

Influence of metal nanoparticles in proton conductivity and water absorption of polymeric membranes for fuel cells

Polymeric membrane fuel cells (PEMFC) are a reality nowadays in several mobile applications, although, their massive use is still not achieved due to the high cost of some components. Alternative membranes of sulfonated poly(styrene-co-acrylic acid) copolymers were prepared, as well as gold and silver nanoparticles through reduction of their salts. The water absorption and proton conductivity of the membrane were evaluated after addition of such metal nanoparticles into the copolymer. Water absorption increased independent of the quantity or nature of the nanometal, compared with a non-doped membrane. Proton conductivity, however, measured through electrochemical impedance spectroscopy (EIS), showed a reduction in values after addition of the nanoparticles, independent of their nature and concentration in the copolymer. On the other hand, a charge transfer resistance, related to the resistance to transfer electrons at the membrane/electrode interface, was enhanced for the nanoparticle doped membranes.

Influence of Metal Nanoparticles on the Soil Microbial Community and Germination of Lettuce Seeds

Short term influence of silica, palladium, gold and copper nanoparticles on a soil microbial community and the germination of lettuce seeds are investigated in this study at two different concentrations of nanoparticles. Results show a statistically insignificant influence of the nanoparticles in the soil on the number of colony forming units, peak areas of methyl ester of fatty acids in the FAME profile or on the total soil community metabolic fingerprint (P > 0.05). Also, all nanoparticles tested in the study influenced the growth of lettuce seeds as measured through shoot/root ratios of the germinated plant (P < 0.05).

Influence of metal nanoparticles on electromagnetic surface waves and laser light scattering

We show that metallic nanoparticles (NP) deposited upon a surface modify its optical properties. Light scattering and its energy level under conditions of surface plasmon resonance are strongly affected by the presence of NP. The results of angle resolved scattering (ARS) measurements of light and scattered light in the configuration of attenuated total reflection by surface plasmon resonance (ATRSPR) are presented. We show that ATRSPR is more sensitive to the presence of NP than ARS.