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  • 1
    Online Resource
    Online Resource
    Wiley ; 2016
    In:  Journal of Applied Polymer Science Vol. 133, No. 38 ( 2016-10-10)
    In: Journal of Applied Polymer Science, Wiley, Vol. 133, No. 38 ( 2016-10-10)
    Abstract: The present work describes the preparation of a set of new polyurea polymers suitable for ballistic protection applications by employing different aromatic diamines derivatives with different flexibility degrees. This modification would allow the synthesis of polymers with both enhanced and controllable mechanical properties through the combination of aliphatic and aromatic molecules. Besides the classical methylene diphenyl diisocyanate and polypropylene glycol bis(2‐aminopropyl ether) (PPG), benzidine, 4,4′‐diaminodiphenylmethane and 3,6‐diamino carbazole were chosen as the third monomer and used in different ratios toward PPG, in order to optimize the polymer properties. The proportions between the polyurea components were selected as such to achieve the total consumption of the monomers. The different types of polyurea obtained have been characterized by Fourier transform infrared spectroscopy, thermal measurements (differential scanning calorimetry and thermogravimetric analysis), tensile tests, and scanning electron microscope. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133 , 43967.
    Type of Medium: Online Resource
    ISSN: 0021-8995 , 1097-4628
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2016
    detail.hit.zdb_id: 1491105-X
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  • 2
    Online Resource
    Online Resource
    Wiley ; 2016
    In:  Propellants, Explosives, Pyrotechnics Vol. 41, No. 6 ( 2016-12), p. 1020-1028
    In: Propellants, Explosives, Pyrotechnics, Wiley, Vol. 41, No. 6 ( 2016-12), p. 1020-1028
    Abstract: This study addresses some aspects regarding water jet propulsion during high explosives detonation. A number of theoretical and experimental studies have shown that using Gurney equation and the relationships derived, one can provide fair results regarding initial velocity of metallic fragments for explosively‐driven metal casings. However, an investigation on Gurney equations utilization for the prediction of water velocity has not been performed yet. By carrying out simple experimental tests and numerical simulations, water has been investigated in terms of total mass average velocity and tip velocity. Based on the available data, the findings indicate that Gurney equations overestimate the water mass average velocity. For water tip velocity evaluation, further studies should be made.
    Type of Medium: Online Resource
    ISSN: 0721-3115 , 1521-4087
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2016
    detail.hit.zdb_id: 1481105-4
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  • 3
    In: Case Studies in Thermal Engineering, Elsevier BV, Vol. 54 ( 2024-02), p. 103987-
    Type of Medium: Online Resource
    ISSN: 2214-157X
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2024
    detail.hit.zdb_id: 2732684-6
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  • 4
    Online Resource
    Online Resource
    Index Copernicus ; 2023
    In:  Problems of Mechatronics Armament Aviation Safety Engineering Vol. 14, No. 2 ( 2023-6-30), p. 9-18
    In: Problems of Mechatronics Armament Aviation Safety Engineering, Index Copernicus, Vol. 14, No. 2 ( 2023-6-30), p. 9-18
    Abstract: The issues related to mechanical resistance of solid rocket propellants, which can appear during storage or handling of the launching system, are considered to directly influence the burning performance. Thus, in this study, four new types of composite rocket propellants, based on an environmentally friendly oxidizer (phase-stabilized ammonium nitrate), a metallic fuel (aluminium), and a "green" polyurethane-based binder (synthesized from an oligomeric isocyanate and a blend of polyester-polyols obtained through the catalytic degradation of polyethylene terephthalate), were subjected to compression mechanical analysis in order to highlight the importance of the binder on the response given by the tested materials subjected to compressive loads. The samples showed remarkable mechanical performances, the experiments allowing us also to determine the influence of the binder composition and fuel granulation on mechanical properties of the composite propellant.
    Type of Medium: Online Resource
    ISSN: 2081-5891 , 2720-5266
    Language: English
    Publisher: Index Copernicus
    Publication Date: 2023
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  • 5
    In: Journal of Applied Polymer Science, Wiley, Vol. 134, No. 28 ( 2017-07-20)
    Abstract: Polyurea nanocomposites represent a promising option in the development of advanced materials for applications that require high mechanical resistance. This article describes an optimized synthetic route for obtaining polyurea nanocomposites with enhanced mechanical properties by employing epoxy‐functionalized multiwalled carbon nanotubes (MWCNTs) as reinforcing agent. The experimental measurements revealed that these functionalized nanofillers have a positive effect on the properties of the composite only until they reach a certain concentration; therefore, the optimal composition was reported (the samples containing 0.2 weight % functionalized MWCNTs). The functionalization of the MWCNTs was confirmed through RAMAN, X‐ray photoelectron spectroscopy, scanning electron microscopy and thermogravimetric analysis, while the polyurea nanocomposites obtained have been characterized by thermal (differential scanning calorimetry and TGA) and mechanical (dynamic mechanical analysis and tensile tests) analyses. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45061.
    Type of Medium: Online Resource
    ISSN: 0021-8995 , 1097-4628
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2017
    detail.hit.zdb_id: 1491105-X
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  • 6
    Online Resource
    Online Resource
    Wiley ; 2015
    In:  Propellants, Explosives, Pyrotechnics Vol. 40, No. 6 ( 2015-12), p. 931-937
    In: Propellants, Explosives, Pyrotechnics, Wiley, Vol. 40, No. 6 ( 2015-12), p. 931-937
    Abstract: During the last decades, authorities’ awareness on environmental and human health impact at national and international level has increased in the field of small arms ammunition containing lead and antimony. Thus, the evolution of environmental policies regarding production and use of heavy metals and their compounds, especially in EU countries, implied extensive studies on the environmental implications of 9×19 mm caliber ammunition use, especially in indoor shooting ranges. In this context, the paper describes the experimental studies performed on Pb‐containing conventional FMJ (full metal jacketed) ammunition and comparative measurements on new ammunition designed for training. The combustion products and residues from conventional Pb‐containing ammunition and Cu‐based “greener” ammunition were compared in terms of gaseous products, metal concentration in aerosols and metal concentrations in solid residues. Gas emissions and solid residues were measured for four different types of ammunitions. The results showed that the copper content of the residue is significantly higher in case of Cu‐containing composite bullets. For the ammunition equipped with Pb bullet, an important percentage of the Pb residue is generated by erosion of the exposed part of the bullet core. On the other hand, the ammunition containing Cu‐composite bullet generates large quantities of Cu residues, which have similar environmental impact and less impact on human health. Gas analysis indicated the presence of CO and NO x and, surprisingly, high concentrations of HCN, CH 4 , and NH 3 . Lower gas concentrations are obtained for the composite bullets due to an incomplete combustion of gun propellant.
    Type of Medium: Online Resource
    ISSN: 0721-3115 , 1521-4087
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2015
    detail.hit.zdb_id: 1481105-4
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  • 7
    In: Water, MDPI AG, Vol. 15, No. 5 ( 2023-03-03), p. 982-
    Abstract: This study presents the formulation and application of strippable coatings for the entrapment and removal of heavy metals (HMs) and radio nuclides (RNs). The “green” formulations involve the use of a water-based solution consisting of a synthetic biodegradable polymer, polyvinyl alcohol (PVA), together with a natural polymer (sodium alginate) as the polymer matrix and bentonite as the reinforcing agent with cation exchange capacity. Four chelating agents comprising two classical chelating agents (ethylenediaminetetraacetic acid (EDTA), diethylenetriamine-pentaacetic acid (DPTA)) and two “green” chelating agents (iminodisuccinic acid (IDS), 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC)) were used to evaluate the capacity to remove Cu, Sb, Zn, Sr, Pb, Co, and Hg from the contaminated surfaces. This decontamination method leads to the formation of a solid waste, thus eliminating the need for wastewater treatment. Atomic absorption spectroscopy (AAS), inductively coupled plasma mass spectrometry (ICP-MS), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), and ultraviolet-visible (UV–Vis) spectroscopy were used to comparatively evaluate the decontamination efficacy. EDX elemental mapping confirmed the entrapment of the contaminants inside the polymeric matrix.
    Type of Medium: Online Resource
    ISSN: 2073-4441
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2521238-2
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  • 8
    In: Applied Sciences, MDPI AG, Vol. 12, No. 24 ( 2022-12-15), p. 12893-
    Abstract: This research describes the design and evaluation of screening smoke compositions based on red phosphorus (RP), in open field conditions. In defense applications, smoke is used for both signaling and screening. Defense forces use smoke screening over their operational areas to conceal positions and activities from the ground or air observation performed by the enemy. In this research, various optimized smoke charges based on RP were prepared and tested to investigate IR and VIS screening effectiveness in static and dynamic conditions and to establish the parameters that influence the screening time (ST- the active time of the small solid hot particles suspended in the air). In addition, this study projected a mathematical model to describe the concealing time of a civil or military target by optimizing the smoke compositions. The mathematical approach clarifies the limitations of reducing smoke charge while maintaining adequate screening time. The empirical mathematical model estimates the screening time of the generated solid smoke particles (aerosol) through laboratory experiments and open field studies. According to the experimental results, more hot particles should be kept in the atmosphere to maintain the smoke screen and sustain the aerosol density in the considered volume.
    Type of Medium: Online Resource
    ISSN: 2076-3417
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2704225-X
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  • 9
    In: Pharmaceutics, MDPI AG, Vol. 15, No. 6 ( 2023-05-24), p. 1588-
    Abstract: Skin infections are frequently treated via intravenous or oral administration of antibiotics, which can lead to serious adverse effects and may sometimes contribute to the proliferation of resistant bacterial strains. Skin represents a convenient pathway for delivering therapeutic compounds, ensured by the high number of blood vessels and amount of lymphatic fluids in the cutaneous tissues, which are systematically connected to the rest of the body. This study provides a novel, straightforward method to obtain nafcillin-loaded photocrosslinkable nanocomposite hydrogels and demonstrates their performance as drug carriers and antimicrobial efficacy against Gram-positive bacteria. The novel formulations obtained, based on polyvinylpyrrolidone, tri(ethylene glycol) divinyl ether crosslinker, hydrophilic bentonite nanoclay, and/or two types of photoactive (TiO2 and ZnO) nanofillers, were characterized using various analytical methods (transmission electron microscopy (TEM), scanning electron microscopy–energy-dispersive X-ray analysis (SEM-EDX), mechanical tests (tension, compression, and shear), ultraviolet-visible spectroscopy (UV-Vis), swelling investigations, and via specific microbiological assays (“agar disc diffusion method” and “time-kill test”). The results reveal that the nanocomposite hydrogel possessed high mechanical resistance, good swelling abilities, and good antimicrobial activity, demonstrating a decrease in the bacteria growth between 3log10 and 2log10 after one hour of direct contact with S. aureus.
    Type of Medium: Online Resource
    ISSN: 1999-4923
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2527217-2
    SSG: 15,3
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  • 10
    Online Resource
    Online Resource
    Brill Osterreich GmbH ; 2001
    In:  Der Donauraum Vol. 41, No. 4 ( 2001-12), p. 74-88
    In: Der Donauraum, Brill Osterreich GmbH, Vol. 41, No. 4 ( 2001-12), p. 74-88
    Type of Medium: Online Resource
    ISSN: 0012-5415 , 2307-289X
    RVK:
    Language: German
    Publisher: Brill Osterreich GmbH
    Publication Date: 2001
    detail.hit.zdb_id: 2751120-0
    detail.hit.zdb_id: 507522-1
    SSG: 7,41
    SSG: 8,1
    SSG: 10
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