Calculation of flight vibration levels of the AH-1G helicopter and correlation with existing flight vibration measurements

Boeing Helicopters, together with other U.S. Helicopter manufacturers, participated in a finite element applications program to give the United States a superior capability to utilize finite element analysis models in support of helicopter airframe design. The program was sponsored by the NASA Langley Research Center. Under this program, an activity was sponsored to evaluate existing analysis methods applicable to calculate coupled rotor-airframe vibrations. The helicopter used in this evaluation was the AH-1G helicopter. The results of the Boeing Helicopters efforts are summarized. The planned analytical procedure is reviewed. Changes to the planned procedure are discussed, and results of the correlation study are presented

Application of reverse micelle sol-gel synthesis for bulk doping and heteroatoms Surface Enrichment in Mo-Doped TiO 2 nanoparticles

TiO 2 nanoparticles containing 0.0, 1.0, 5.0, and 10.0 wt.% Mo were prepared by a reverse micelle template assisted sol-gel method allowing the dispersion of Mo atoms in the TiO 2 matrix. Their textural and surface properties were characterized by means of X-ray powder diffraction, micro-Raman spectroscopy, N 2 adsorption/desorption isotherms at -196 °C, energy dispersive X-ray analysis coupled to field emission scanning electron microscopy, X-ray photoelectron spectroscopy, diffuse reflectance UV-Vis spectroscopy, and ζ-potential measurement. The photocatalytic degradation of Rhodamine B (under visible light and low irradiance) in water was used as a test reaction as well. The ensemble of the obtained experimental results was analyzed in order to discover the actual state of Mo in the final materials, showing the occurrence of both bulk doping and Mo surface species, with progressive segregation of MoO x species occurring only at a higher Mo content

Synthesis and characterization of p-n junction ternary mixed oxides for photocatalytic coprocessing of CO2 and H2O

In the present paper, we report the synthesis and characterization of both binary (Cu2 O, Fe2 O3, and In2 O3 ) and ternary (Cu2 O-Fe2 O3 and Cu2 O-In2 O3 ) transition metal mixed-oxides that may find application as photocatalysts for solar driven CO2 conversion into energy rich species. Two different preparation techniques (High Energy Milling (HEM) and Co-Precipitation (CP)) are compared and materials properties are studied by means of a variety of characterization and analytical techniques UV-Visible Diffuse Reflectance Spectroscopy (UV-VIS DRS), X-ray Photoelectron Spectroscopy (XPS), X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and Energy Dispersive X-Ray spectrometry (EDX). Appropriate data elaboration methods are used to extract materials bandgap for Cu2 O@Fe2 O3 and Cu2 O@In2 O3 prepared by HEM and CP, and foresee whether the newly prepared semiconductor mixed oxides pairs are useful for application in CO2-H2 O coprocessing. The experimental results show that the synthetic technique influences the photoactivity of the materials that can correctly be foreseen on the basis of bandgap experimentally derived. Of the mixed oxides prepared and described in this work, only Cu2 O@In2 O3 shows positive results in CO2-H2 O photo-co-processing. Preliminary results show that the composition and synthetic methodologies of mixed-oxides, the reactor geometry, the way of dispersing the photocatalyst sample, play a key role in the light driven reaction of CO2 –H2 O. This work is a rare case of full characterization of photo-materials, using UV-Visible DRS, XPS, XRD, TEM, EDX for the surface and bulk analytical characterization. Surface composition may not be the same of the bulk composition and plays a key role in photocatalysts behavior. We show that a full material knowledge is necessary for the correct forecast of their photocatalytic behavior, inferred from experimentally determined bandgaps

Opto‐Electronic Characterization of Photocatalysts Based on p,n‐Junction Ternary and Quaternary Mixed Oxides Semiconductors (Cu2O‐In2O3 and Cu2O‐In2O3‐TiO2)

Semiconductor materials are the basis of electronic devices employed in the communication and media industry. In the present work, we report the synthesis and characterization of mixed metal oxides (MOs) as p,n‐junction photocatalysts, and demonstrate the correlation between the preparation technique and the properties of the materials. Solid‐state UV-visible diffuse reflectance spectroscopy (UV‐VIS DRS) allowed for the determination of the light absorption properties and the optical energy gap. X‐ray photoelectron spectroscopy (XPS) allowed for the determination of the surface speciation and composition and for the determination of the valence band edge. The opto‐electronic behavior was evaluated measuring the photocurrent generated after absorption of chopped visible light in a 3‐electrode cell. Scanning electron microscopy (SEM) measurements allowed for auxiliary characterization of size and morphology, showing the formation of composites for the ternary Cu2O‐In2O3 p,n‐mixed oxide, and even more for the quaternary Cu2O‐In2O3‐TiO2 MO. Light absorption spectra and photocurrent‐time curves mainly depend upon the composition of MOs, while the optical energy gap and defective absorption tail are closely related to the preparation methodology, time and thermal treatment. Qualitative electronic band structures of semiconductors are also presented

Ag-based synergistic antimicrobial composites. A critical review

The emerging problem of the antibiotic resistance development and the consequences that the health, food and other sectors face stimulate researchers to find safe and effective alternative methods to fight antimicrobial resistance (AMR) and biofilm formation. One of the most promising and efficient groups of materials known for robust antimicrobial performance is noble metal nanoparticles. Notably, silver nanoparticles (AgNPs) have been already widely investigated and applied as antimicrobial agents. However, it has been proposed to create synergistic composites, because pathogens can find their way to develop resistance against metal nanophases; therefore, it could be important to strengthen and secure their antipathogen potency. These complex materials are comprised of individual components with intrinsic antimicrobial action against a wide range of pathogens. One part consists of inorganic AgNPs, and the other, of active organic molecules with pronounced germicidal effects: both phases complement each other, and the effect might just be the sum of the individual effects, or it can be reinforced by the simultaneous application. Many organic molecules have been proposed as potential candidates and successfully united with inorganic counterparts: polysaccharides, with chitosan being the most used component; phenols and organic acids; and peptides and other agents of animal and synthetic origin. In this review, we overview the available literature and critically discuss the findings, including the mechanisms of action, efficacy and application of the silver-based synergistic antimicrobial composites. Hence, we provide a structured summary of the current state of the research direction and give an opinion on perspectives on the development of hybrid Ag-based nanoantimicrobials (NAMs)

Platinum(IV) complexes of trans-1,2-diamino-4-cyclohexene: Prodrugs affording an oxaliplatin analogue that overcomes cancer resistance

Six platinum(IV) compounds derived from an oxaliplatin analogue containing the unsaturated cyclic diamine trans-1,2-diamino-4-cyclohexene (DACHEX), in place of the 1,2-diaminocyclohexane, and a range of axial ligands, were synthesized and characterized. The derivatives with at least one axial chlorido ligand demonstrated solvent-assisted photoreduction. The electrochemical redox behavior was investigated by cyclic voltammetry; all compounds showed reduction potentials suitable for activation in vivo. X-ray photoelectron spectroscopy (XPS) data indicated an X-ray-induced surface reduction of the Pt(IV) substrates, which correlates with the reduction potentials measured by cyclic voltammetry. The cytotoxic activity was assessed in vitro on a panel of human cancer cell lines, also including oxaliplatin-resistant cancer cells, and compared with that of the reference compounds cisplatin and oxaliplatin; all IC50 values were remarkably lower than those elicited by cisplatin and somewhat lower than those of oxaliplatin. Compared to the other Pt(IV) compounds of the series, the bis-benzoate derivative was by far (5–8 times) the most cytotoxic showing that low reduction potential and high lipophilicity are essential for good cytotoxicity. Interestingly, all the complexes proved to be more active than cisplatin and oxaliplatin even in three-dimensional spheroids of A431 human cervical cancer cells

A Review on Montmorillonite-Based Nanoantimicrobials: State of the Art

One of the crucial challenges of our time is to effectively use metal and metal oxide nanoparticles (NPs) as an alternative way to combat drug-resistant infections. Metal and metal oxide NPs such as Ag, Ag2O, Cu, Cu2O, CuO, and ZnO have found their way against antimicrobial resistance. However, they also suffer from several limitations ranging from toxicity issues to resistance mechanisms by complex structures of bacterial communities, so-called biofilms. In this regard, scientists are urgently looking for convenient approaches to develop heterostructure synergistic nanocomposites which could overcome toxicity issues, enhance antimicrobial activity, improve thermal and mechanical stability, and increase shelf life. These nanocomposites provide a controlled release of bioactive substances into the surrounding medium, are cost effective, reproducible, and scalable for real life applications such as food additives, nanoantimicrobial coating in food technology, food preservation, optical limiters, the bio medical field, and wastewater treatment application. Naturally abundant and non-toxic Montmorillonite (MMT) is a novel support to accommodate NPs, due to its negative surface charge and control release of NPs and ions. At the time of this review, around 250 articles have been published focusing on the incorporation of Ag-, Cu-, and ZnO-based NPs into MMT support and thus furthering their introduction into polymer matrix composites dominantly used for antimicrobial application. Therefore, it is highly relevant to report a comprehensive review of Ag-, Cu-, and ZnO-modified MMT. This review provides a comprehensive overview of MMT-based nanoantimicrobials, particularly dealing with preparation methods, materials characterization, and mechanisms of action, antimicrobial activity on different bacterial strains, real life applications, and environmental and toxicity issues

Reverse Micelle Strategy for the Synthesis of MnOx-TiO2Active Catalysts for NH3-Selective Catalytic Reduction of NOxat Both Low Temperature and Low Mn Content

MnOx-TiO2catalysts (0, 1, 5, and 10 wt % Mn nominal content) for NH3-SCR (selective catalytic reduction) of NOxhave been synthesized by the reverse micelle-assisted sol-gel procedure, with the aim of improving the dispersion of the active phase, usually poor when obtained by other synthesis methods (e.g., impregnation) and thereby lowering its amount. For comparison, a sample at nominal 10 wt % Mn was obtained by impregnation of the (undoped) TiO2sample. The catalysts were characterized by using an integrated multitechnique approach, encompassing X-ray diffraction followed by Rietveld refinement, micro-Raman spectroscopy, N2isotherm measurement at −196 °C, energy-dispersive X-ray analysis, diffuse reflectance UV-vis spectroscopy, temperature-programmed reduction technique, and X-ray photoelectron spectroscopy. The obtained results prove that the reverse micelle sol-gel approach allowed for enhancing the catalytic activity, in that the catalysts were active in a broad temperature range at a substantially low Mn loading, as compared to the impregnated catalyst. Particularly, the 5 wt % Mn catalyst showed the best NH3-SCR activity in terms of both NOxconversion (ca. 90%) and the amount of produced N2O (ca. 50 ppm) in the 200-250 °C temperature range

Oxidized alginate dopamine conjugate: In vitro characterization for nose-to-brain delivery application

Background: The blood–brain barrier (BBB) bypass of dopamine (DA) is still a challenge for supplying it to the neurons of Substantia Nigra mainly affected by Parkinson disease. DA prodrugs have been studied to cross the BBB, overcoming the limitations of DA hydrophilicity. Therefore, the aim of this work is the synthesis and preliminary characterization of an oxidized alginatedopamine (AlgOX-DA) conjugate conceived for DA nose-to-brain delivery. Methods: A Schiff base was designed to connect oxidized polymeric backbone to DA and both AlgOX and AlgOX-DA were characterized in terms of Raman, XPS, FT-IR, and1H-NMR spectroscopies, as well as in vitro mucoadhesive and release tests. Results: Data demonstrated that AlgOX-DA was the most mucoadhesive material among the tested ones and it released the neurotransmitter in simulated nasal fluid and in low amounts in phosphate buffer saline. Results also demonstrated the capability of scanning near-field optical microscopy to study the structural and fluorescence properties of AlgOX, fluorescently labeled with fluorescein isothiocyanate microstructures. Interestingly, in SH-SY5Y neuroblastoma cell line up to 100 µg/mL, no toxic effect was derived from AlgOX and AlgOX-DA in 24 h. Conclusions: Overall, the in vitro performances of AlgOX and AlgOX-DA conjugates seem to encourage further ex vivo and in vivo studies in view of nose-to-brain administration

Non-invasive characterization of hybrid gelatin:poly-L-lactide electrospun scaffolds using second harmonic generation and multiphoton imaging

In this work we generated hybrid gelatin:poly-l-lactide electrospun scaffolds and implemented non-invasive methods to characterize them