bluuebunny/crossref_metadata_2025 huggingface dataset:
Induced seismicity: a geo-ecological problem of a technogenic nature
Authors: Tashlykova Tatiana G. , Ryashchenko Tamara G. , Dolgaya Anna A. , Lukyanova Elena A.
Published: September 2016

A debatable problem of the display of induced seismicity and its causes during the construction of reservoirs (Reservoir Induced Seismicity - RIS) is considered on the basis of an analysis of various publications. This paper describes the history of the evolution of ideas about the possibility of the activation of seismic events in the zones of influence of artificial reservoirs and examples of such activation in aseismic areas, which is a medium geological response to technogenic interference (e.g. Shivajisagar reservoir in West India, Mead reservoir in the USA, Danjiangkou Reservoir in central China, Nurek reservoir in Central Asia, Chirkey reservoir in Dagestan and other). The problem and reasons of induced seismicity (RIS) are debatable. however, published examples demonstrate the existence of this process. For reservoirs with different amounts of water RIS is an inseparable component of the natural and man-made geological process. The world statistics knows cases of seismicity intensification in areas near small man-made reservoirs with low pressure levels (Belecha in former Yugoslavia, Marathon in Greece, Grandval in France). In addition, it was found that the number of local earthquakes increased after creating a cascade of three small water reservoirs (Studen Kladenets, Kardzhali and Ivaylovgrad) in the basin of The Arda river (Bulgaria). The RIS examples listed above allow us to think that it is not only the creation of large reservoirs that change (in some cases, intensifies) the local seismicity in the surrounding area. No reservoir, no matter what size it is, is insured from such geological process. At the present time there are more than 100 places in the world with displays of induced seismicity due to reservoir construction. In India there are up to eight reservoirs with these problems. Induced seismicity associated with the influence of man-made water reservoirs, causes a specific geo-ecological risks to the surrounding areas.
Green synthesis of a carbon-rich layer on the surface of SiC at room temperature by anodic etching in dilute hydrofluoric acid/ethylene glycol solution
Authors: Cao Tuan Anh , Luong Truc Quynh Ngan , Dao Tran Cao
Published: September 2016

Carbide-derived carbons (CDCs) are a growing class of nanostructured carbon materials with properties that are desirable for many applications, ranging from electrical energy to gas storage. However, the synthesis of CDCs often requires high temperatures and/or pressures, as well as toxic chemicals. In this report, we demonstrate environmentally friendly synthesis of a carbon-rich layer on the surface of SiC by anodic etching at room temperature in a highly diluted solution of hydrofluoric acid in ethylene glycol. In our opinion, the carbon-rich layer was formed thanks to the fact that we have used the etching conditions in which the rate of removal of carbon from SiC has become significantly lower compared with the silicon removal rate. More specifically, we have created an environment for SiC anodic etching where there is little water. In such conditions, silicon is still being removed from SiC, thanks to the direct dissolution, whereas the carbon removal rate is significantly reduced, due to the fact that carbon can be lost only by oxidation, but there is not enough water to oxidize carbon as in solutions with plenty of water. Thus, a carbon-rich layer is created on the etched SiC surface.
Structural characterization of copper complexes with chiral 1,2,4-triazine-oxazoline ligands
Authors: Wolińska Ewa , Karczmarzyk Zbigniew , Wysocki Waldemar
Published: September 2016

The crystal structure determination of oxazoline-1,2,4-triazine ligand 1f and pyridine-oxazoline ligand 2g was used to analyze their conformational preferences when forming complexes with metals. Proton nuclear magnetic resonance (1H NMR), electrospray ionization mass spectrometry and UV-vis spectroscopy as well as theoretical calculation using molecular mechanics (MM) were adopted to study the composition and geometry of oxazoline-1,2,4-triazine ligands 1 complexes with copper(II) acetate monohydrate. The study revealed that during the complexation, (i) Cu(II) ion is reduced to Cu(I) upon the ligand-to-metal charge transfer transition and (ii) the ligands form with copper(I) 2:1 (L:Cu) complexes of tetrahedral geometry. On the basis of the findings, the catalytic cycle and the active transition state for the enantioselective nitroaldol reaction (the Henry reaction) catalyzed by 1–Cu are proposed.
Gender, Museums and Science: Wanda Hanke’s Ethnological Collections (1933–1958)
Authors: Sombrio Mariana M. O.
Published: September 2016

This paper will explore the significance of the expeditions under- taken by Wanda Hanke (1893-1958) in South America, of the networks she established in the region, as well as of her contributions to ethnological studies, in particular her compilation of extensive data and collections. Through Hanke's experience, it is possible to elucidate aspects of the history of ethnology and that of the history of museums in Brazil, as well as to emphasize the status of female participation in these areas. Wanda Hanke spent 25 years of her life studying the indigenous groups of Argentina, Bolivia, Brazil and Paraguay and collecting ethnological objects for natural history museums. Trained in medicine and philosophy, she began to dedicate herself to ethnological studies in her forties, and she travelled alone, an uncommon characteristic among female scientists in the 1940s, in Brazil.
Directional measures of postural sway as predictors of balance instability and accidental falls
Authors: Janusz Błaszczyk W. , Beck Monika , Szczepańska Justyna , Sadowska Dorota , Bacik Bogdan , Juras Grzegorz , Słomka Kajetan J.
Published: September 2016

Despite the obvious advantages and popularity of static posturography, universal standards for posturographic tests have not been developed thus far. Most of the center-of-foot pressure (COP) indices are strongly dependent on an individual experimental design, and are susceptible to distortions, which makes results of their analysis incomparable. In this research, we present a novel approach to the analysis of the COP trajectory based on the directional features of postural sway. Our novel output measures: the sway directional indices (DI) and sway vector (SV) were applied to assess the postural stability in the group of young able-bodied subjects. Towards this aim, the COP trajectories were recorded in 100 students standing still for 60 s, with eyes open (EO) and then, with eyes closed (EC). Each record was subdivided then into 20, 30 and 60 s samples. Interclass correlation coefficients were calculated from the samples. The controlled variables (visual conditions) uniquely affected the output measures, but only in case of proper signal pretreatment (low-pass filtering). In filtering below 6 Hz, the DI and SV provided a unique set of descriptors for postural control. Both sway measures were highly independent of the trial length and the sampling frequency, and were unaffected by the sampling noise. Directional indices of COP filtered at 6 Hz showed high to very high reliability, with ICC range of 0.7-0.9. Results of a single 60 s trial are sufficient to reach acceptable reliability for both DI and SV. In conclusion, the directional sway measures may be recommended as the primary standard in static posturography.
Optimizing post activation potentiation for explosive activities in competitive sports
Authors: Gołaś Artur , Maszczyk Adam , Zajac Adam , Mikołajec Kazimierz , Stastny Petr
Published: September 2016

Post activation potentiation (PAP) has shown improved performance during movements requiring large muscular power output following contractions under near maximal load conditions. PAP can be described as an acute enhancement of performance or an enhancement of factors determining an explosive sports activity following a preload stimulus. In practice, PAP has been achieved by complex training, which involves a combination of a heavy loaded exercise followed by a biomechanically similar explosive activity, best if specific for a particular sport discipline. The main objective of this study was to investigate the effects of PAP on performance in explosive motor activities specific for basketball, luge and athletics throws. The novel approach to the experiments included individualized recovery time (IRT) between the conditioning exercise and the explosive activity. Additionally, the research groups were homogenous and included only competitive athletes of similar age and training experience. Thirty one well trained athletes from 3 different sport disciplines participated in the study. All athletes performed a heavy loaded conditioning activity (80-130%1RM) followed by a biomechanically similar explosive exercise, during which power (W) or the rate of power development (W/s/kg) was evaluated. The results of our experiment confirmed the effectiveness of PAP with well-trained athlets during explosive motor activities such as jumping, throwing and pushing. Additionally, our research showed that eccentric supramaximal intensities (130% 1RM) can be effective in eliciting PAP in strength trained athletes. Our experiments also showed that the IRT should be individualized because athletes differ in the strength level, training experience and muscle fiber structure. In the three experiments conducted with basketball players, track and field athletes and luge athletes, the optimal IRT equaled 6 min. This justifies the need to individualize the volume and intensity of the CA, and especially the IRT, between the CA and the explosive activity.
The muscle-mechanical compromise framework: Implications for the scaling of gait and posture
Authors: Usherwood James Richard (Jim)
Published: September 2016

Many aspects of animal and human gait and posture cannot be predicted from purely mechanical work minimization or entirely based on optimizing muscle efficiency. Here, the Muscle-Mechanical Compromise Framework is introduced as a conceptual paradigm for considering the interactions and compromises between these two objectives. Current assumptions in implementing the Framework are presented. Implications of the compromise are discussed and related to the scaling of running mechanics and animal posture.
The effects of specific drills on the flip turns of freestyle swimmers based on a kinesiology analysis
Authors: Wen Yuhong , Peng Yi , Zhao Feng , Zhen Kexin
Published: September 2016

This research aimed to define the key factors in freestyle flip turns via a kinesiology analysis to diagnose swimmers. Hence, specially designed drills were created to improve swimmers’ flip-turn skills and assess the effects of training. Nine Chinese national modern pentathlon athletes ranging in age from 20 to 26 years with an average of 10 years of training experience were tested and trained in this study. The Kistler Performance Analysis System for Swimming was used for the pre- and post-test analyses. A kinesiology analysis of the data from the pre-test was used for the diagnosis and specific drills were adopted for 10 weeks, 3 times per week before the post-test. The comparison of the pre- and post-test performances was used to assess the effects of training. After 10 weeks of specific drill training for flip turns, participants’ turning skills significantly improved. Speed in approaching, somersaulting, pushing-off and gliding all increased. The angles of the knees and hips as well as the force applied improved, which contributed to swimmers’ increased speed. Since the skills needed for a flip turn are complex and not easily diagnosed via observation alone, this kinesiology analysis will make diagnosis objective and easy.
Hybrid Synchronization Between 5-th Order Hyperchaotic Chua Systems
Authors: Chantov Dragomir
Published: September 2016

The aim of this paper is the design of a chaotic synchronization system with a special type of synchronization, called hybrid synchronization, on the basis of Chua’s fifth-order hyperchaotic model. When two chaotic systems are in hybrid synchronization, some of the systems’ variables pairs are in identical synchronization, and the rest are anti-synchronized. Hybrid synchronization schemes have advantages regarding the degree of signal protection, when they are used to build a chaotic secure communication system. The design of the system is accomplished by means of active control, where the Second Lyapunov method is used to prove the stability of the synchronization system.
Optimal Control of the Flow of Risk on Networks
Authors: Sgurev Vassil , Drangajov Stanislav
Published: September 2016

A new network flow method is proposed in this work for optimal distribution of risk between the different sections (arcs) of the network. It is supposed at that that the maximum admissible risks on the arcs are known in advance. This provides a possibility these values to be considered as arc capacities and the risk itself as a network flow. Such an approach lets the maximal admissible risk to be determined on the network on the base of the well-known mincut-maxflow theorem as well as the minimal cut. Three different numerical examples are given through which the possibility of the method being proposed is confirmed in the real practices.
Study of a Computer-Based Control System with Fault-Tolerant and Fail-Safe Behavior
Authors: Hristova Mariya
Published: September 2016

The software and hardware of Safety Critical Systems - SCS, which control special critical technology process or operation, are subject of enhanced requirements for reliability and inadmissibility of any incorrect controlling influences (safety) after failures. This paper suggests and investigates a hybrid computerbased fail-safe/fault-tolerance FST-structure with single reservation, which has the qualities to meet these requirements. The base system 2 ∨ 2, based on which it is built, is studied in the previous edition of Information Technjlogies and Control. For derivation of probabilistic models through which to establish the efficiency of the strutucral redundancy in a fault-tolerant structure, in this paper are used the published results. Formulas are derived for the probability of failure-free operation (availability coefficient), for safe failure and for unidentified (dangerous) failure. Models are found for calculation of the enhancement of reliability and the variation of safety relative to the base system 2 ∨ 2. Subject of analysis are type software and hardware modifications of the proposed general scheme used in the practice of different companies, which manufacture and operate SCSs. It is proven that at the expense of acceptable hardware redundancy and insignificant increase of dangerous failures the probability of interruption of the operation of the FST- system and its down-time due to failure may decrease by tenths of thousands of times.
Insecticidal efficacy of silica nanoparticles against Rhyzopertha dominica F. and Tribolium confusum Jacquelin du Val
Authors: Ziaee Masumeh , Ganji Zahra
Published: September 2016

Bioassays were conducted to assess the effects of two silicon dioxide nanoparticles of Aerosil® and Nanosav against adults of Rhyzopertha dominica F. and Tribolium confusum Jacquelin du Val. Silica nanoparticles were applied at the rates of 50, 100, 200 and 300 mg · kg−1 on wheat and peeled barley. The mortality was counted after 1, 2, 3, and 7 days of exposure. Another experiment was carried out to evaluate the effect of food source on the survival of beetles after exposure to silica nanoparticles. Adults were exposed to silica nanoparticles at the rate of 0.2 mg · cm−2 for 1 and 2 days on filter paper inside plastic Petri dishes, respectively. After exposure, the initial mortality was counted and live individuals of both species were held for a week in empty glass vials or vials containing wheat and wheat flour, respectively. Silica nanoparticles have high toxicity on R. dominica and T. confusum adults. Rhyzopertha dominica was more susceptible than T. confusum. However, the mortality of both species increased with increasing concentrations and time exposed to each concentration. At low concentrations, Aerosil® was more effective than Nanosav. Silica nanoparticles were more effective in wheat grains than barley. Results indicated that the initial mortality was so high that the impact of food source on delay mortality was unclear in most cases. Silica nanoparticles were efficient against tested species and can be used effectively in a stored grain integrated pest management program.
Microstructural, optical and electrical properties of Cl-doped CdTe single crystals
Authors: Choi Hyojeong , Kim Han Soo , Oh Joon-Ho , Kim Dong Jin , Kim Young Soo , Chai Jong-Seo , Ha Jang Ho
Published: September 2016

Microstructural, optical and electrical properties of Cl-doped CdTe crystals grown by the low pressure Bridgman (LPB) method were investigated for four different doping concentrations (unintentionally doped, 4.97 × 1019 cm−3, 9.94 × 1019 cm−3 and 1.99 × 1020 cm−3) and three different locations within the ingots (namely, samples from top, middle and bottom positions in the order of the distance from the tip of the ingot). It was shown that Cl dopant suppressed the unwanted secondary (5 1 1) crystalline orientation. Also, the average size and surface coverage of Te inclusions decreased with an increase in Cl doping concentration. Spectroscopic ellipsometry measurements showed that the optical quality of the Cl-doped CdTe single crystals was enhanced. The resistivity of the CdTe sample doped with Cl at the 1.99 × 1020 cm−3 was above 1010 Ω.cm.
Crystal structure of catena-poly-[(1-cyclopropyl-6-fluoro-4-oxo-7-(piperazin-1-ium-1-yl)-1,4-dihydroquinoline-3-carboxylate-κ
2
O,O′)-(μ2-4,4′-sulfonyldibenzoato-κ
4
O,O′:O′′,O′′′)zinc(II)] hemihydrate, C31H27ZnFN3O9.5S
Authors: Fan Zhuo-Wen , Wang Liang-Liang , Cui Kuo , Meng Ying , Liu Ji-Zhi
Published: September 2016

C31H27ZnFN3O9.5S, triclinic, P1̅ (no. 2), a = 10.6434(4) Å, b = 12.6191(4) Å, c = 12.8532(5) Å, α = 93.998(3)°, β = 109.121(3)°, γ = 112.773(3)°, V = 1465.16(9) Å3, Z = 2, R
gt(F) = 0.0354, wR
ref(F
2) = 0.1012, T = 293 K.
Crystal structure of 2-(2-bromophenyl)-5-ethyl-1,3-dioxane-5-carboxylic acid, C13H15BrO4
Authors: Yuan Lin , Yuan Xian-You , Li Zhong-Yan , Zhang Min
Published: September 2016

C13H15BrO4, orthorhombic, Pbca (no. 61), a = 15.894(3) Å, b = 7.6064(16) Å, c = 21.571(4) Å, V = 2607.8(9) Å3, Z = 8, R
gt(F) = 0.0268, wR
ref(F
2) = 0.0702, T = 296(2) K.
Crystal structure of 8-isopropyl-8-aza-bicyclo[3.2.1]octan-3-ol, C10H19NO
Authors: Yang Xiao-Li , Wang Kun-Yan
Published: September 2016

C10H19NO, monoclinic, P21/c (no. 14), a = 6.2427(16) Å, b = 9.553(2) Å, c = 16.932(4) Å, β = 100.094(7)°, V = 994.1(4) Å3, Z = 4, R
gt(F) = 0.060, wR
ref(F
2) = 0.094, T = 296(2) K.
Crystal structure of 2,4-dibenzoyl-N,N-dimethylbenzenamine, C22H19NO2
Authors: Wang Kai , Chen Qiang , Xiao Jian
Published: September 2016

C22H19NO2, monoclinic, P21/c (no. 14), a = 12.7728(19) Å, b = 7.9765(12) Å, c = 20.451(3) Å, β = 123.946(7)°, V = 1728.5(5) Å3, Z = 4, R
gt(F) = 0.049, wR
ref(F
2) = 0.150, T = 296(2) K.
“The True Forme of Love”: Transforming the Petrarchan Tradition in the Poetry of Lady Mary Wroth (1587–1631)
Authors: Jajtner Tomáš
Published: September 2016

The following article deals with the transformation of the Petrachan idea of love in the work of Lady Mary Wroth (1587-1631), the first woman poet to write a secular sonnet sequence in English literature, Pamphilia to Amphilanthus. The author of the article discusses the literary and historical context of the work, the position of female poets in early modern England and then focuses on the main differences in Wroth’s treatment of the topic of heterosexual love: the reversal of gender roles, i.e., the woman being the “active” speaker of the sonnets; the de-objectifying of the lover and the perspective of love understood not as a possessive power struggle, but as an experience of togetherness, based on the gradual interpenetration of two equal partners.
Assimilating American Indians in James Fenimore Cooper’s Novels?
Authors: Peprník Michal
Published: September 2016

The article employs critical concepts from sociology and anthropology to examine the stereotype of the Vanishing Indian and disclose its contradictory character. The article argues that in James Fenimore Cooper’s late novels from the 1840s a type of American Indian appears who can be regarded as a Vanishing Indian in many respects as he displays some slight degree of assimilation but at the same time he can be found to reveal a surprising amount of resistance to the process of vanishing and marginalization. His peculiar mode of survival and his mode of living demonstrate a certain degree of acculturation, which comes close to Gerald Vizenor’s survivance and for which I propose a term critical integration. I base my study on Susquesus (alias Trackless), Cooper’s less well-known character from The Littlepage Manuscripts, a three-book family saga.
Fabrication of chitosan/PEO nanofiber mats with mica by electrospinning
Authors: Chen Qi , Xin Zhen Xiang , Saha Prosenjit , Kim Jin Kuk
Published: September 2016

Chitosan (CS) is an excellent biocompatible natural antibacterial material that has attracted researchers to study its biological applications as artificial tissue scaffolds and wound-healing materials. In this research, CS has been mixed with polyethylene oxide (PEO) and mica at various weight ratios to prepare nanofibers; however, it is found to be a difficult task to prepare the nanofiber using pure CS. The composite in form of nanofibrous mat was prepared with CS/PEO solution and CS/PEO/mica solution using electrospinning. Processing conditions were adjusted to a flow rate of 6 ml/min, with an applied voltage of 27 kV. The distance of capillary tip to target was kept about 10 cm at 25°C with a collector having a speed of 200 rpm. The spinnability of solutions was also evaluated by using both plate and cylinder collectors. The composite mats were analyzed in detail using scanning electron microscopy (SEM), Fourier transform infrared (FTIR), thermogravimetric analysis, and X-ray diffractogram (XRD). SEM photomicrograms indicated that the morphology and diameter of the nanofibers were affected by weight ratio of CS/PEO, concentration of mica, and types of collector. Furthermore, mica was incorporated in the CS/PEO matrix to enhance the specific surface area. Molecular interactions between CS/PEO and mica were investigated using FTIR and XRD.
The influence of physical activity on climacteric symptoms
Authors: Dąbek Aneta , Adamiec Agnieszka , Rekowski Witold , Czyżewski Piotr
Published: September 2016

Introduction: The menopausal syndrome affects 85-87% post-menopausal women. Typical symptoms include: hot flashes, heavy sweats, dizziness, increased body temperature, heart palpitations, depression, mood swings, distorted concentration, distorted memory and interrupted sleeping patterns. The literature on effects of physical activity on menopausal symptoms seems to be inconsistent. The aim of this study was to determine the relationship between intensified menopausal syndrome and undertaking physical activity.

Material and methods: We studied 105 healthy menopausal women (aged 45 to 65). Their mean age was 52 SD 5.2. We used the survey method. The research tools were: questionnaire we devised, Kupperman index and Borg scale. Additionally, we devised: physical effort intensity index and physical activity variety index. To conduct the statistical analysis, we used STATISTICA programme. We set statistical significance at p<0.05.

Results: We found a statistically significant relationship between the frequency of undertaking physical activity and the intensity of menopausal syndrome. More than a half of the subjects (54.3%) did physical exercise “often” or “regularly”, and they did not suffer from the “severe” form of menopausal syndrome. We found a significant relationship between the BMI and intensity of menopausal symptoms (p=0.04) and between the waist size and menopausal symptoms (p=0.001).

Conclusions: The more intense, varied and frequent physical activity, the less intense menopausal symptoms. The subjects with normal BMI and waist narrower than 80cm had less difficult menopause. Physical activity reduces physical and psychological changes experienced in the climacteric.
Thermal expansion, electrical conductivity and hardness of Mn3Zn0.5Sn0.5N/Al composites
Authors: Miao Jinjin , Liu Jiaqi , Wu Xiao , Zou Han , Sha Dawei , Ren Jie , Dai Yu , Yan Xuehua , Cheng Xiaonong
Published: September 2016

Mn3Zn0.5Sn0.5N/Al composites were successfully prepared by sintering at 623 K and 723 K. It is found that the thermal expansion of Al is effectively decreased with the addition of negative thermal expansion material Mn3Zn0.5Sn0.5N, which plays the role of the thermal expansion compensator in the composite system. The thermal expansion of composites can be tailored by adjusting the volume fraction of Mn3Zn0.5Sn0.5N. In particular, 40 vol.%-Mn3Zn0.5Sn0.5N/Al composite sintered at 723 K has a low thermal expansion coefficient of 2.38×10−6 K−1. The thermal expansion of Mn3Zn0.5Sn0.5N/Al composites matches well with those calculated from the rule of mixture (ROM) estimation. The ROM model can be used to predict the thermal expansion of Mn3Zn0.5Sn0.5N/Al composite and design Mn3Zn0.5Sn0.5N/Al composite with a particular thermal expansion. Mn3Zn0.5Sn0.5N/Al composites exhibit excellent electrical conductivities at the level of 104 S/cm. The hardness of the as-prepared composites increases by adding Mn3Zn0.5Sn0.5N in Al.
Preparation and erosion-corrosion behavior of polyetheretherketone (PEEK)/nickel foam co-continuous composites
Authors: Yang X.G. , Duan D.L. , Jiang S.L. , Li S. , Zhang H.C.
Published: September 2016

Polyetheretherketone (PEEK)/Ni foam co-continuous composites were designed and prepared via the hot pressing technique, and their erosion-corrosion behaviors were evaluated using an impinging jet apparatus in 1% H2SO4 and 5% silica sand with a flow rate of 30 m/s. Optical microscopy and scanning electron microscopy were used to describe the damage morphologies. A strong combination was shown between Ni foam and PEEK in the composites. PEEK was reinforced with Ni foam, and the erosion-corrosion resistance of the composites increased with the decreasing density and pore size of Ni foam. Volume loss under normal impact was higher than that under oblique impact.
High-speed electrical sliding wear behaviors of Cu-WS2-graphite-WS2 nanotubes composite
Authors: Qian Gang , Feng Yi , Zhang Jing-Cheng , Wang Yang , Zhang Tian-Ci , Xiao Ke-Song
Published: September 2016

Cu-WS2-graphite-WS2 nanotubes composite was fabricated by the powder metallurgy hot-pressed method. The effects of electrical current (5–15 A/cm2) and sliding velocity (5–15 m/s) on the electrical wear behaviors of the composite were investigated using a block-on-slip ring wear tester rubbing against Cu-5 wt% Ag alloy ring under 2.5 N/cm2 of applied load. The lubricating effect of WS2 nanotubes and composition of tribo-film were analyzed. The results demonstrated that the contact resistance decreases but the wear rate increases as electrical current increases, because the adverse effects of electrical current soften the materials at “a-spots” and damage the tribo-film. Due to the adsorption of gaseous molecule film on the tangential direction of slip ring surface, with the rise of sliding velocity, the contact resistance increases while the wear rate reaches the minimum at a sliding velocity of 10 m/s. The reasonable addition of WS2 nanotubes into the Cu-WS2-graphite composite to replace WS2 powder can result in a reduction of both contact resistance and wear rate. X-ray photoelectron spectroscopy (XPS) analyses revealed that copper oxides, graphite, WS2 and WS2 nanotubes in the tribo-film play the main lubrication action at the tribo-interface.
Reinforcing abilities of microfibers and nanofibrillated cellulose in poly(lactic acid) composites
Authors: Tanpichai Supachok , Wootthikanokkhan Jatuphorn
Published: September 2016

The reinforcing abilities of cellulose microfibers and nanofibrillated cellulose (NFC) in poly(lactic acid) (PLA) were evaluated. NFC successfully prepared from regenerated cellulose fibers using high-speed blending for 60 min was introduced in a PLA matrix. The physical and mechanical properties of NFC-reinforced PLA composites were investigated in comparison with those of the composites with microfibers. NFC fibrils with diameters in the range of 100–500 nm were disintegrated from micron-sized regenerated fibers. A slight decrease in the degree of crystallinity and degradation temperature obtained for NFC after mechanical treatment was found compared with untreated microfibers. The introduction of NFC in the PLA effectively increased the tensile strength and Young’s modulus of the composites by 18% and 42%, respectively. The use of micron-sized fibers to reinforce PLA, on the other hand, showed a slight improvement in Young’s modulus (13%). The improvement in the mechanical properties of the composites reinforced with NFC was found because of the higher surface area of NFC and better interaction between the matrix and NFC fibrils. This allowed stress to transfer from the matrix to the reinforcement. NFC prepared using the high-speed blending could be an alternative to use as reinforcement in composites.
What is Time in Some Modern Physics Theories: Interpretation Problems
Authors: Karpenko Ivan A.
Published: September 2016

The article deals with the problem of time in the context of several theories of modem physics. This fundamental concept inevitably arises in physical theories, but so far there is no adequate description of it in the philosophy of science. In the theory of relativity, quantum field theory. Standard Model of particle physics, theory of loop quantum gravity, superstring theory and other most recent theories the idea of time is shown explicitly or not. Sometimes, such as in the special theory of relativity, it plays a significant role and sometimes it does not. But anyway it exists and is implied by the content of the theory, which in some cases directly includes its mathematical tools. Fundamental difference of space-time processes in microcosm and macrocosm is of particular importance for solving the problem. In this regard, a need to understand the time in the way it appears in modem physics, to describe it in the language of philosophy arises (satisfactory for time description mathematical tools also do not exist). This will give an opportunity to get closer to the answer on question of time characteristics. And even if we do not obtain the exact answer, we will still be able to formulate the right question about its nature. For this purpose, the present research carries out analysis of the key theories of modern physics with regard to historical and scientific, historical and philosophical perspectives, hi some cases, this gives an opportunity to detect the succession of the associated with time perception ideas, their development, as well as the origination of fundamentally new ones. During the analysis, the conect characteristics of time are formulated from the point of view of physical theory and the attempt to state the nature of time is made. On the ground of conducted research, the conclusions about current state of the problem and its future solution perspectives are drawn.
Logics for Physarum Chips
Authors: Schumann Andrew , Pancerz Krzysztof
Published: September 2016

The paper considers main features of two groups of logics for biological devices, called Physarum Chips, based on the plasmodium. Let us recall that the plasmodium is a single cell with many diploid nuclei. It propagates networks by growing pseudopodia to connect scattered nutrients (pieces of food). As a result, we deal with a kind of computing. The first group of logics for Physarum Chips formalizes the plasmodium behaviour under conditions of nutrient-poor substrate. This group can be defined as standard storage modification machines. The second group of logics for Physarum Chips covers the plasmodium computing under conditions of nutrient-rich substrate. In this case the plasmodium behaves in a massively parallel manner and propagates in all possible directions. The logics of the second group are unconventional and deal with non-well-founded data such as infinite streams.
The ZIF system zinc(II) 4,5-dichoroimidazolate: theoretical and experimental investigations of the polymorphism and crystallization mechanisms
Authors: Springer Sergej , Heidenreich Niclas , Stock Norbert , van Wüllen Leo , Huber Klaus , Leoni Stefano , Wiebcke Michael
Published: September 2016

In this report, we summarize our theoretical and experimental investigations on the zeolitic imidazolate framework (ZIF) system [Zn(dcim)2] (dcim=4,5-dichloroimidazolate) that have been published recently. These comprise: (1) a theoretical study on hypothetical conformational [Zn(dcm)2]-SOD polymorphs with the same underlying sodalite (SOD) topology but distinct dcim linker orientations, (2) a synthetic work that resulted in the experimental realization of the most stable predicted (trigonal) SOD-type framework conformer and improved synthetic protocols for a previously discovered cubic SOD-type material, (3) a detailed structural analysis of the trigonal and cubic SOD-type materials, (4) a comparative characterization of the SOD-type materials by gas physisorption measurements, (5) a synthetic work that resulted in the discovery of a complete series of intermediate frameworks with the trigonal and cubic SOD-type materials as the end members, and (6) time-resolved in-situ light and stopped-flow synchrotron small-angle and wide-angle X-ray scattering experiments on the rapid crystallization of the RHO-type polymorph (ZIF-71). In addition, we report as yet unpublished work, concerning time-resolved in-situ angular-dispersive synchrotron X-ray diffraction experiments on RHO-/SOD-type phase selection via the coordination modulation approach during competitive formation of the RHO-type and SOD-type materials.
Arylimido zirconium and titanium complexes: characteristic structures and application in ethylene polymerization
Authors: Yuan Shifang , Wang Lijing , Hua Yupeng , Zhang Jing , Sun Wen-Hua
Published: September 2016

Dimeric anilidolithium (ArHNLi·Et2O)2 (Ar=2,6-
i
Pr2C6H3) reacted with zirconium tetrachloride in THF to give the heterometallic zirconium–lithium complex [(Et2O)2Li(μ-Cl)2(ArHN)(ArN=)Zr(μ-Cl)]2 (C1) and with titanium tetrachloride in toluene to give the titanium complex [(ArN=)TiCl2·(Et2O)2] (C2) each in good isolated yields. Their molecular structures in the solid state were confirmed by X-ray diffraction analysis. Upon activation with methylaluminoxane, both arylimido zirconium and titanium complexes exhibited good catalytic activities toward ethylene polymerization.
Highly specific “sensing” of tryptophan by a luminescent europium(III) complex
Authors: Stubenrauch Jan A. , Mevissen Christian , Schulte Marie F. , Bochenek Steffen , Albrecht Markus , Subramanian Palani S.
Published: September 2016

The europium(III) complex 1-Cl3 (S,S-2,2′-(((1,10-phenanthroline-2,9-diyl)bis(methanylylidene))bis(azanylylidene))bis(3-methylbutanamide)europiumtrichloride) undergoes, only in the presence of the amino acid tryptophan, a change of emission at 615 nm. In the presence of few equivalents of tryptophan, emission of the europium complex is enhanced while it disappears upon addition of large amounts. This behavior can be assigned to displacement of the sensitizing phenanthroline ligand of 1-Cl2•Trp in the latter case.
Syntheses and crystal structures of two new silver–organic frameworks based on N-pyrazinesulfonyl-glycine: weak Ag···O/N interaction affecting the coordination geometry
Authors: Li Jia-Ming , He Kun-Huan , Shi Zhong-Feng , Gao Hui-Yuan , Jiang Yi-Min
Published: September 2016

Two new metal–organic frameworks, namely, [Ag2(L)]
n
(1) and {[Ag2.5(L)(bpy)2]·(NO3)0.5·(H2O)4.5}
n
(2), where H2L=N-pyrazinesulfonyl-glycine and bpy=4,4′-bipyridine, have been synthesized and characterized by single-crystal X-ray diffraction, IR spectroscopy, and elemental analysis. X-ray diffraction crystallographic analyses indicate that 1 displays a silver carboxylate-sulfonamide layer structure containing an uncommon heptanuclear [Ag7] cluster wherein four silver(I) atoms form an Ag4 plane with in a three-connected (6, 3) net. The molecular structure of 2 has three crystallographically independent two-coordinate Ag centers with an intersecting Ag-bpy chain structure in a six-connected (3, 6) or a four-connected (4, 4) topology. The L2− ligand serves as a μ
7-(η
2-O,N), (η
2-O′,N′), O,O″,O″′,N,N″ ligand in 1 and as a μ
3-(η
2-O,N), N,O′ ligand in 2. In the crystal, a 3D supramolecular architecture is formed by coordinative bonding in 1, but through O–H···O bonding as well as π···π stacking in 2. The two compounds show a combination of coordinative bonds, ligand-supported Ag···Ag interactions and weak Ag···O/N coordinative interactions in the solid state.
Synthesis and characterization of allyl- and vinyl-substituted 1,2-bis(tetrazolo)ethanes as polymeric precursors
Authors: Hartdegen Vera A. , Hofmayer Maximilian S. , Karaghiosoff Konstantin , Klapötke Thomas M.
Published: September 2016

On the basis of 1,2-bis(5-tetrazolo)ethane (BTE) the corresponding twofold vinyl and allyl N-substituted derivatives were synthesized using 1,2-dibromoethane and allyl bromide, respectively. The compounds were obtained as two different constitutional isomers. Both species were analyzed using NMR and IR spectroscopy, elemental analysis, as well as mass spectrometry. In the case of the diallyl bistetrazoles, the two isomers were characterized using 2D NMR spectroscopy. The synthesis of the divinyl compounds gave crystals of the 2,2′-N-substituted isomer, which were analyzed by single-crystal X-ray diffraction. The thermal stability of the compounds was determined using differential scanning calorimetry (DSC) and gave decomposition temperatures around 190°C and 230°C. For the investigation of the inherent energetic potential, sensitivities toward physical stimuli and detonation parameters were determined. The compounds turned out to be insensitive toward friction and impact and possess moderate energetic properties.
Volumetric, Ultrasonic and Viscometric Studies of Aspirin in the Presence of 1-Octyl-3-Methylimidazolium Bromide Ionic Liquid in Acetonitrile Solutions at T=(288.15–318.15) K
Authors: Shekaari Hemayat , Taghi Zafarani-Moattar Mohammed , Mirheydari Seyyedeh Narjes
Published: September 2016

In a continuation of previous studies, thermophysical properties of the systems containing aspirin (ASA), ionic liquid, 1-octyl-3-methylimidazolium bromide ([OMIM][Br]) and acetonitrile (MeCN) have been determined. These properties contain density, viscosity, speed of sound and refractive index measured at T=(288.15 K–318.15 K) and at atmospheric pressure. The measured data have been applied to calculate the apparent molar volumes at infinite dilution

V
φ
0

,

$V_\varphi ^0,$

transfer volumes

Δ

V
φ
0

,

$\Delta V_\varphi ^0,$

apparent molar isentropic compressibilities κ

ϕ
, to viscosity B-coefficients and solvation number. The positive values of

Δ

V
φ
0

$\Delta V_\varphi ^0$

and

Δ

κ
φ
0

$\Delta \kappa _\varphi ^0$

indicate that dominant interactions between ASA and ionic liquid are ion–polar and polar–polar interactions. From the obtained parameters, some information in regard with the solute–solvent interactions in the studied systems was obtained. The cosphere overlap model was used to interpret the positive transfer volume

Δ

V
φ
0

.

$\Delta V_\varphi ^0.$
Analysis of Risks to Oxygen Systems from Particulate and Fiber Contaminants and Derivation of Cleanliness Requirements
Authors: Lowrey Nikki M.
Published: September 2016

It has been well documented in the literature that contamination within oxygen systems can create significant fire hazards. Cleanliness limits for nonvolatile residues, ranging from 10 to 500 mg/m2, have been established for various industries and types of oxygen systems to reduce the risk of ignition of flammable organic films. Particulate cleanliness limits used for oxygen systems vary considerably. Maximum allowed particle size, quantity limits, and allocations for fibers or metallic particles are all variables seen in aerospace cleanliness limits. Particles are known to have the potential to ignite within oxygen systems and must be limited to prevent fires. Particulate contamination may also pose risks to the performance of oxygen systems that may or may not be related to ignition hazards. An extensive literature search was performed to better understand the relative importance of particle ignition mechanisms versus other deleterious effects of particles on oxygen systems and to identify rationale for derivation of particulate cleanliness limits for specific systems. The identified risks of different types and sizes of particles and fibers were analyzed. This paper summarizes the risks identified and rationale that may be used to derive particulate cleanliness limits for specific oxygen systems.
Detailed Investigation of the Sequence of Mechanisms Participating in Metals Ignition in Oxygen Using Laser Heating and In Situ, Real-Time Diagnostics
Authors: Muller Maryse , El-Rabii Hazem , Fabbro Rémy , Coste Frédéric , Rostaing Jean-Christophe , Ridlova Martina , Colson Alain , Barthélémy Hervé
Published: September 2016

Fire incidents involving oxygen piping and associated equipment that have occurred below the exemption pressure threshold (per the European Industrial Gases Association [EIGA] 13/12 and the Compressed Gas Association [CGA] G4.4 standards) might motivate exploitation of additional, nonexplicit information gathered from the ASTM G124 promoted ignition and combustion test (PICT). For that, it is necessary to analyze quantitatively the complete sequence of phenomena involved in ignition then transition to propagation. First, we consider the elementary heat and mass transfer/oxidation system extending over a small depth beneath the cross section of a rod-shaped sample, heated fully controllably by an incident laser beam in gaseous oxygen. An oxygen jet flow at normal incidence reproduces the dynamic pressure condition that would occur from a local flowing pattern on a surface element of a hollow body's inner wall in a real-life system. In situ, real-time diagnostics include high-speed imaging and temperature measurements by optical pyrometry. Parameters are laser power (maximum 3–4 kW) and time of exposure to radiation, oxygen flow velocity (1 to 60 ms−1), and pressure (1 to 21 bara). The investigated parametric domain represents thousands of experiments for carbon steel and stainless steel. Ignition occurs at a characteristic critical temperature, corresponding to thermally induced loss of integrity of the primarily formed passivating oxide; although, in the case of stainless steel, a particular multistep mechanism is involved. The amount of deposited energy necessary for ignition is reduced when laser power is increased. Oxygen jet flow velocity and pressure have a negligible effect on ignition energy. Beyond the limits of this geometry (selected initially for simplicity), we now have a robust quantitative methodology for transposition to investigating puncture ignition and breach expansion for a pressurized hollow vessel, as well as the details of physical mechanisms in PICT.
A Method for Autogenous Ignition Temperature Determination of Metal Through Induction Heating
Authors: Stoltzfus Joel , Gallus Timothy D.
Published: September 2016

To assist in the failure analysis of a rocket thruster, the ignition temperature in oxygen-enriched atmospheres of titanium and titanium alloys was investigated. The open literature indicated melting temperatures in the range of 1,660°C (3,020°F) and ignition temperatures ranging from 250 to 1,627°C (482 to 2,961°F) for titanium powder and solid titanium, respectively. Vertically mounted test samples of varying diameters were ignited by induction heating in 66 % oxygen (O2)/balance nitrogen (N2) and in 99.5 + % O2 at 1,000 psia. Ignition was measured by either a platinum/platinum-rhodium (Type S) thermocouple comprised of 0.05-mm (0.002 in.) and 0.076-mm (0.003 in.) diameter wires welded to the samples or by a two-color pyrometer. The ignition temperatures in 66 % O2 and 99.5 + % O2, with various surface treatments and configurations, ranged from 1,623 to 1,659°C (2,953 to 3,018°F). The lack of an effect on ignition temperature as a function of oxygen concentration suggests that the ignition process is controlled by subsurface rather than surface-related processes. One unexpected result was that although sample nitriding did not change the autogenous ignition temperature (AIT), it did change the rate of combustion after ignition.
Evaluation of Containment Boxes as a Fire Mitigation Method in Elevated Oxygen Conditions
Authors: Juarez Alfredo , Harper Susana A. , Perez Horacio
Published: September 2016

NASA performed testing to evaluate the efficacy of fire containment boxes without forced ventilation. Configurational flammability testing was performed on a simulation avionics box replicating critical design features and filled with materials possessing representative flammability characteristics. This paper discusses the box's ability, under simulated end-use conditions, to inhibit the propagation of combustion to surrounding materials. Analysis was also performed to evaluate the potential for the fire containment box to serve as an overheat/ignition source to temperature sensitive equipment (such as items with lithium-ion batteries). Unrealistically severe combustion scenarios were used as a means to better understand the fire containment mechanism. These scenarios were achieved by utilizing materials/fuels not typically used in space vehicles due to flammability concerns. Oxygen depletion, during combustion within the fire containment boxes, drove self-extinguishment and proved an effective method of fire containment.
Factors Affecting NVR Contaminant Fire Risk
Authors: Forsyth Bradley S. , Chiffoleau Gwenael J. A. , Newton Barry E.
Published: September 2016

Cleanliness is considered a foundational element of a safe oxygen system or component. Contaminants, particularly in the form of hydrocarbon oil or grease surface films, are considered more ignitable than the bulk materials of a component or system. Furthermore, ignition of oil or grease films is often an initiating event in fires where a kindling chain develops, eventually involving the bulk materials of the component or system. This paper describes several primary factors related to the fire risk of predominantly nonvolatile residue (NVR) contaminants. The present understanding of these factors is reviewed with discussion of applicable historical research, and new data are presented for some factors. The combined collection of research is then discussed in the context of industry standards and guidelines regarding contaminant cleanliness levels.