scholarly journals Aspects of nanomaterials for civil and military applications. Part 2. Their use and concerns arising from their release into the natural environment

Author(s):  
Zenon Foltynowicz ◽  
Bogdan Czajka ◽  
Andrzej Maranda ◽  
Leszek Wachowski

The dynamic development of nanoscience and nanotechnology has led to revolutionary changes in many areas of science and industry, raising a great deal of hope for its potential to solve a wide range of problems of the modern world. Nanomaterials, also referred to as engineered nanoparticles are a product of nanotechnology and, compared to macro-particles, show unique physical, chemical, biological and mechanical properties which significantly extend the range of practical applications. The paper presents the applicability of engineered nanoparticles in the defence industry and concerns related to their release into the environment.

Author(s):  
Michał Chmielarek ◽  
Wincenty Skupiński ◽  
Zdzisław Wieczorek

Hydroxyl-terminated polybutadiene is widely used in industry for both civil and military applications. In munitions, HTPB is mostly used as a binder for heterogenic rocket propellants and as a component of plastic bonded explosives, as well as a phlegmatizer in explosives sensitive to friction and impact. The wide range of HTPB applications results from the good mechanical properties of HTPB-based polyurethanes, in particular at temperatures down to –40 °C. A synthesis method for HTPB, different from the commonly used semi-batch and continuous methods, is presented. The effect of parameters including reaction temperature, 1,3-butadiene pressure and hydrogen peroxide concentration on the properties of the obtained polymer is determined. The synthesis conditions enabling new HTPB species to be obtained, which meet the requirements for binders used in solid rocket propellants, are specified.


2017 ◽  
Vol 266 ◽  
pp. 3-7
Author(s):  
Syed H. Riza ◽  
Ashish M. Ashok ◽  
Syed H. Masood ◽  
Igor Sbarski

The Selective Laser Melting (SLM) process has been proved as the most effective method among Additive Manufacturing (AM) technologies to produce hard, dense and strong metallic structures with intricate shapes and profiles from wide range of metallic alloys. The SLM generated structures from 17-4PH stainless steel high strength alloys involve layer by layer building up through laser melting of successively deposited powder layers. Therefore, the mechanical properties of such structures need to be thoroughly checked and investigated before putting these materials to practical applications. This research mainly investigates the cryogenic impact properties of SLM generated 17-4PH specimen. These characteristics are very important in applications requiring high strength customized structures that could maintain their mechanical properties at sub-zero temperatures. The experimental analysis proves that SLM is a very reliable technology to produce high strength metallic structures and these specimens can function efficiently in extreme conditions.


2015 ◽  
Vol 1110 ◽  
pp. 27-31
Author(s):  
Du Yuan ◽  
Xi Wen Zhang ◽  
Xiao Shan Fan ◽  
Chao Bin He

The development of nanocomposites promising a wide range of interesting properties such as mechanical, optical and electrical conductivity is under intense investigation. One key challenge towards practical applications lies in effective dispersion of nanofillers in the polymer matrices. An one-pot wet-chemistry synthesis approach was developed for successful fabrication of surface modified SiO2nanoparticles@epoxy nanocomposites (1 wt%). Homogeneous nanofiller dispersion was obtained in SiO2-epoxide@epoxy. Importantly, the SiO2-epoxide@epoxy presented its enhanced mechanical properties with reference to pure epoxy, i.e., ~ 77% increase in maximum tensile stress and ~ 19% increase in Young’s modulus. This was attributed to the much improved dispersion of nanofillers and the optimized interaction between nanofillers and matrix. Further, SiO2-epoxide@epoxy prepared from master batch with 80 wt% SiO2loading retained the good dispersion of nanofillers and enhanced mechanical properties. This demonstration allows future implementation of the developed approach for the surface modified SiO2@epoxy nanocomposites towards industrial applications.


1946 ◽  
Vol 19 (4) ◽  
pp. 876-899
Author(s):  
Jean Le Bras

Abstract If it is attempted to sum up the important results obtained in the present study, the following points seem to be well established. First of all, with respect to selenium. Whether the oxidizabilities of products vulcanized by selenium alone or of products vulcanized by a mixture of selenium and sulfur are measured, they show the same general behavior as do mixtures vulcanized by sulfur alone. It is the percentage of vulcanizing agent in combined form that governs the oxidizability, for the addition of selenium to sulfur increases this oxidizability. If part of the sulfur is replaced by selenium, there is a decrease in the oxidizability, but this can be explained by the lesser reactivity of the selenium, as a result of which the product is vulcanized to a less extent. It is not true, then, that, for a given state of cure, selenium improves aging. The case of diazoaminobenzene is a more complicated one. This compound decomposes during vulcanization, with liberation of nitrogen and probable formation of antioxygenic substances such as diphenylamine. Diazoaminobenzene itself is a proöxygenic substance, and mixtures containing it which have been heated only a short time have a strong tendency to oxidize. With longer heating, complete decomposition of the diazoaminobenzene inevitably takes place, and the oxidizability becomes established at a relatively small value. In the same way, with chloranil and with dichloroiminoquinone, the reaction leads to the formation of antioxygenic substances, and when vulcanization is carried to a sufficient point, the oxidizability decreases. It should be mentioned that such a prolongation of the time of heating does not have any harmful effect on the mechanical properties of the vulcanizate. Actually all the agents gave a remarkably broad plateau, and no appreciable differences in mechanical properties were found over a wide range of heating times, e.g., 30 minutes to 8 hours. As for the joint use of an amine and an oxidizing agent, such as N, N′-di-β-naphthyl-p-phenylenediamine and lead peroxide, it will be found that, here too, with increase in the time of vulcanization the tendency to oxidize decreases to a minimum, probably as a result of progressive decomposition of the peroxide. if it is attempted to counteract this proöxygenic action directly by the addition of a large amount of the amine, it will be found that, on the contrary, vulcanization becomes less and less effective and the oxidizability increases. However, by adjusting the proportions of amine and of oxidizing agent judiciously, it is possible to obtain products the resistance of which to oxidation is remarkably good. In a special experiment, a direct comparison was made of samples vulcanized with the agents described in the present work and a simple rubber-sulfur vulcanizate, both unprotected and protected by different antioxygenic substances, including diphenylamine, hydroquinone and N, N′-di-β-naphthyl-p-phenylenediamine. By plotting the results, the curves shown in Figure 13 were obtained. These curves make particularly clear the fact that it is possible, by means of certain vulcanizing agents, e.g., diazoaminobenzene or an amine plus an oxidizing agent, to obtain vulcanizates which have as much resistance to oxidation as that of rubber-sulfur vulcanizates containing an antioxygenic substance. This is not true of nitro compounds, with which even ordinary antioxygenic agents have only a relatively slight protective action. A thorough investigation of these vulcanizing agents is then of importance, not only in helping to explain the mechanism of vulcanization itself but also because of the possibilities of its leading to various practical applications.


Author(s):  
Ernest L. Hall ◽  
J. B. Vander Sande

The present paper describes research on the mechanical properties and related dislocation structure of CdTe, a II-VI semiconductor compound with a wide range of uses in electrical and optical devices. At room temperature CdTe exhibits little plasticity and at the same time relatively low strength and hardness. The mechanical behavior of CdTe was examined at elevated temperatures with the goal of understanding plastic flow in this material and eventually improving the room temperature properties. Several samples of single crystal CdTe of identical size and crystallographic orientation were deformed in compression at 300°C to various levels of total strain. A resolved shear stress vs. compressive glide strain curve (Figure la) was derived from the results of the tests and the knowledge of the sample orientation.


Author(s):  
J.M. Cowley

The HB5 STEM instrument at ASU has been modified previously to include an efficient two-dimensional detector incorporating an optical analyser device and also a digital system for the recording of multiple images. The detector system was built to explore a wide range of possibilities including in-line electron holography, the observation and recording of diffraction patterns from very small specimen regions (having diameters as small as 3Å) and the formation of both bright field and dark field images by detection of various portions of the diffraction pattern. Experience in the use of this system has shown that sane of its capabilities are unique and valuable. For other purposes it appears that, while the principles of the operational modes may be verified, the practical applications are limited by the details of the initial design.


Author(s):  
Kateryna Iorgachova ◽  
Olga Makarova ◽  
Karyne Avetisian

In the presented work the choice of starch syrup for the jelly products production has been substantiated. It was based on the analysis of the starch syrup carbohydrate profiles and recipes of jelly products. The influence of syrup on the rheological and structural-mechanical properties of jelly and aerated masses for a two-layer jelly has been determined. The expediency of polydextrose usage has been demonstrated. Its adding leads to the regulation of the jelly structure and foam layer for the samples with more than 50% of sugar replaced by starch syrup. Depending on the ratio of carbohydrates in jelly it was determined the amount of polydextrose adding of which provides the required firming and prebiotic properties of finish products. The change of physical-chemical, structural-mechanical, and organoleptic quality indices of two-layer jelly with modified carbohydrate composition has been investigated during storage.


Author(s):  
Yulia V. Paukova ◽  
◽  
Konstantin V. Popov ◽  

The present article considers the need to predict migration flows using Predictive Analytics. The Russian Federation is a center of migration activity. The modern world is changing rapidly. An effective migration policy requires effective monitoring of migration flows, assessing the current situation in our and other countries and forecasting migration processes. There are information systems in Russia that contain a wide range of information about foreign citizens and stateless persons that provide the requested information about specific foreign citizens, including grouping it on various grounds. However, it is not possible to analyze and predict it automatically using thousands of parameters. Special attention in Russia is paid to digitalization. Using information technologies (artificial intelligence, machine learning and big data analysis) to forecast migration flows in conditions of variability of future events will allow to take into account a number of events and most accurately predict the quantitative and so-called "qualitative" structure of arrivals. The received information will help to develop state policy and to take appropriate measures in the field of migration regulation. The authors come to the conclusion that it is necessary to amend existing legal acts in order to implement information technologies of Predictive Analytics into the practice of migration authorities.


2020 ◽  
pp. 39-48
Author(s):  
B. O. Bolshakov ◽  
◽  
R. F. Galiakbarov ◽  
A. M. Smyslov ◽  
◽  
...  

The results of the research of structure and properties of a composite compact from 13 Cr – 2 Мо and BN powders depending on the concentration of boron nitride are provided. It is shown that adding boron nitride in an amount of more than 2% by weight of the charge mixture leads to the formation of extended grain boundary porosity and finely dispersed BN layers in the structure, which provides a high level of wearing properties of the material. The effect of boron nitride concentration on physical and mechanical properties is determined. It was found that the introduction of a small amount of BN (up to 2 % by weight) into the compacts leads to an increase in plasticity, bending strength, and toughness by reducing the friction forces between the metal powder particles during pressing and a more complete grain boundary diffusion process during sintering. The formation of a regulated structure-phase composition of powder compacts of 13 Cr – 2 Mо – BN when the content of boron nitride changes in them allows us to provide the specified physical and mechanical properties in a wide range. The obtained results of studies of the physical and mechanical characteristics of the developed material allow us to reasonably choose the necessary composition of the powder compact for sealing structures of the flow part of steam turbines, depending on their operating conditions.


2018 ◽  
Vol 35 (4) ◽  
pp. 62-64
Author(s):  
Nazar Ul Islam Wani

Pilgrimage in Islam is a religious act wherein Muslims leave their homes and spaces and travel to another place, the nature, geography, and dispositions of which they are unfamiliar. They carry their luggage and belongings and leave their own spaces to receive the blessings of the dead, commemorate past events and places, and venerate the elect. In Pilgrimage in Islam, Sophia Rose Arjana writes that “intimacy with Allah is achievable in certain spaces, which is an important story of Islamic pilgrimage”. The devotional life unfolds in a spatial idiom. The introductory part of the book reflects on how pilgrimage in Islam is far more complex than the annual pilgrimage (ḥajj), which is one of the basic rites and obligations of Islam beside the formal profession of faith (kalima); prayers (ṣalāt); fasting (ṣawm); and almsgiving (zakāt). More pilgrims throng to Karbala, Iraq, on the Arbaeen pilgrimage than to Mecca on the Hajj, for example, but the former has received far less academic attention. The author expands her analytic scope to consider sites like Konya, Samarkand, Fez, and Bosnia, where Muslims travel to visit countless holy sites (mazarāt), graves, tombs, complexes, mosques, shrines, mountaintops, springs, and gardens to receive the blessings (baraka) of saints buried there. She reflects on broader methodological and theoretical questions—how do we define religion?—through the diversity of Islamic traditions about pilgrimage. Arjana writes that in pilgrimage—something which creates spaces and dispositions—Muslim journeys cross sectarian boundaries, incorporate non-Muslim rituals, and involve numerous communities, languages, and traditions (the merging of Shia, Sunni, and Sufi categories) even to “engende[r] a syncretic tradition”. This approach stands against the simplistic scholarship on “pilgrimage in Islam”, which recourses back to the story of the Hajj. Instead, Arjana borrows a notion of ‘replacement hajjs’ from the German orientalist Annemarie Schimmel, to argue that ziyārat is neither a sectarian practice nor antithetical to Hajj. In the first chapter, Arjana presents “pilgrimage in Islam” as an open, demonstrative and communicative category. The extensive nature of the ‘pilgrimage’ genre is presented through documenting spaces and sites, geographies, and imaginations, and is visualized through architectural designs and structures related to ziyārat, like those named qubba, mazār (shrine), qabr (tomb), darih (cenotaph), mashhad (site of martyrdom), and maqām (place of a holy person). In the second chapter, the author continues the theme of visiting sacred pilgrimage sites like “nascent Jerusalem”, Mecca, and Medina. Jerusalem offers dozens of cases of the ‘veneration of the dead’ (historically and archaeologically) which, according to Arjana, characterizes much of Islamic pilgrimage. The third chapter explains rituals, beliefs, and miracles associated with the venerated bodies of the dead, including Karbala (commemorating the death of Hussein in 680 CE), ‘Alawi pilgrimage, and pilgrimage to Hadrat Khidr, which blur sectarian lines of affiliation. Such Islamic pilgrimage is marked by inclusiveness and cohabitation. The fourth chapter engages dreams, miracles, magical occurrences, folk stories, and experiences of clairvoyance (firāsat) and the blessings attached to a particular saint or walī (“friend of God”). This makes the theme of pilgrimage “fluid, dynamic and multi-dimensional,” as shown in Javanese (Indonesian) pilgrimage where tradition is associated with Islam but involves Hindu, Buddhist and animistic elements. This chapter cites numerous sites that offer fluid spaces for the expression of different identities, the practice of distinct rituals, and cohabitation of different religious communities through the idea of “shared pilgrimage”. The fifth and final chapter shows how technologies and economies inflect pilgrimage. Arjana discusses the commodification of “religious personalities, traditions and places” and the mass production of transnational pilgrimage souvenirs, in order to focus on the changing nature of Islamic pilgrimage in the modern world through “capitalism, mobility and tech nology”. The massive changes wrought by technological developments are evident even from the profusion of representations of Hajj, as through pilgrims’ photos, blogs, and other efforts at self documentation. The symbolic representation of the dead through souvenirs makes the theme of pilgrimage more complex. Interestingly, she then notes how “virtual pilgrimage” or “cyber-pilgrimage” forms a part of Islamic pilgrimage in our times, amplifying how pilgrimage itself is a wide range of “active, ongoing, dynamic rituals, traditions and performances that involve material religions and imaginative formations and spaces.” Analyzing religious texts alone will not yield an adequate picture of pilgrimage in Islam, Arjana concludes. Rather one must consider texts alongside beliefs, rituals, bodies, objects, relationships, maps, personalities, and emotions. The book takes no normative position on whether the ziyāratvisitation is in fact a bid‘ah (heretical innovation), as certain Muslim orthodoxies have argued. The author invokes Shahab Ahmad’s account of how aspects of Muslim culture and history are seen as lying outside Islam, even though “not everything Muslims do is Islam, but every Muslim expression of meaning must be constituting in Islam in some way”. The book is a solid contribution to the field of pilgrimage and Islamic studies, and the author’s own travels and visits to the pilgrimage sites make it a practicalcontribution to religious studies. Nazar Ul Islam Wani, PhDAssistant Professor, Department of Higher EducationJammu and Kashmir, India


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