bluuebunny/crossref_metadata_2025_split huggingface dataset:
Research on Photodegradation of Norfloxacin by Modified Carbon Nitrogen Compounds
Authors: ENZI ZHAI 
Published: January 2021

Abstract
Photocatalysis is an economical and reliable method for degradation of pharmaceutical pollutants. Under mild conditions, the photocatalyst can absorb optical energy and accelerate the photo degradation of pollutants. As a new type of non-metallic semiconductor catalyst, graphite phase carbon nitride(g-C3N4) has many excellent properties such as low band gap, large specific surface area and so on. Norfloxacin (NOR) is a synthetic antibiotic with many good properties such as high antibacterial activity and low toxicity. Because of its wide application in medical treatment and animal breeding, it has caused great pollution to the environment. In this paper, the performance of g-C3N4 and the mechanism of photocatalytic degradation of NOR are analyzed. Several effective modification methods are described, and several problems that need to be solved in current research are put forward.
Nanofibril-mediated fracture resistance of bone
Authors: Tertuliano Ottman A , Edwards Bryce W , Meza Lucas R , Deshpande Vikram S , Greer Julia R 
Published: January 2021

Abstract
Natural hard composites like human bone possess a combination of strength and toughness that exceeds that of their constituents and of many engineered composites. This augmentation is attributed to their complex hierarchical structure, spanning multiple length scales; in bone, characteristic dimensions range from nanoscale fibrils to microscale lamellae to mesoscale osteons and macroscale organs. The mechanical properties of bone have been studied, with the understanding that the isolated microstructure at micro- and nano-scales gives rise to superior strength compared to that of whole tissue, and the tissue possesses an amplified toughness relative to that of its nanoscale constituents. Nanoscale toughening mechanisms of bone are not adequately understood at sample dimensions that allow for isolating salient microstructural features, because of the challenge of performing fracture experiments on small-sized samples. We developed an in situ three-point bend experimental methodology that probes site-specific fracture behavior of micron-sized specimens of hard material. Using this, we quantify crack initiation and growth toughness of human trabecular bone with sharp fatigue pre-cracks and blunt notches. Our findings indicate that bone with fatigue cracks is two times tougher than that with blunt cracks. In situ data-correlated electron microscopy videos reveal this behavior arises from crack-bridging by nanoscale fibril structure. The results reveal a transition between fibril-bridging (∼1 μm) and crack deflection/twist (∼500 μm) as a function of length-scale, and quantitatively demonstrate hierarchy-induced toughening in a complex material. This versatile approach enables quantifying the relationship between toughness and microstructure in various complex material systems and provides direct insight for designing biomimetic composites.
CEST MRI trackable nanoparticle drug delivery systems
Authors: Han Zheng , Liu Guanshu 
Published: January 2021

Abstract
Mounting evidence shows the great promise of nanoparticle drug delivery systems (nano-DDSs) to improve delivery efficiency and reduce off-target adverse effects. By tracking drug delivery and distribution, monitoring nanoparticle degradation and drug release, aiding and optimizing treatment planning, and directing the design of more robust nano-DDSs, image guidance has become a vital component of nanomedicine. Recently, chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) has emerged as an attempting imaging method for achieving image-guided drug delivery. One of the unbeatable advantages of CEST MRI is its ability to detect diamagnetic compounds that cannot be detected using conventional MRI methods, making a broad spectrum of bioorganic agents, natural compounds, even nano-carriers directly MRI detectable in a high-spatial-resolution manner. To date, CEST MRI has become a versatile and powerful imaging technology for non-invasive in vivo tracking of nanoparticles and their loaded drugs. In this review, we will provide a concise overview of different forms of recently developed, CEST MRI trackable nano-DDSs, including liposomes, polymeric nanoparticles, self-assembled drug-based nanoparticles, and carbon dots. The potential applications and future perspectives will also be discussed.
Supermultiplicative relations in models of interacting self-avoiding walks and polygons
Authors: Janse van Rensburg E J 
Published: January 2021

Abstract
Fekete’s lemma shows the existence of limits in subadditive sequences. This lemma, and generalisations of it, also have been used to prove the existence of thermodynamic limits in statistical mechanics. In this paper it is shown that the two variable supermultiplicative relation

p

n

1

(

m

1

)

p

n

2

(

m

2

)

⩽

p

n

1

+

n

2

(

m

1

+

m

2

)

together with mild assumptions, imply the existence of the limit

log

P

#

(

ϵ

)

=

lim

n
→
∞

1

n

log

p

n

(

⌊

ϵ
n

⌋

)

.

This is a generalisation of Fekete’s lemma. The existence of

log

P

#

(

ϵ

)

is proven for models of adsorbing walks and polygons, and for pulled polygons. In addition, numerical data are presented estimating the general shape of

log

P

#

(

ϵ

)

of models of square lattice self-avoiding walks and polygons.
Experimental characterisation of a flax fibre - epoxy resin composite
Authors: Artimon Flavia , Stochioiu C , Gheorghiu H M , Sima Iuliana 
Published: January 2021

Abstract
In the recent years, the scientific community’s attention has gradually started to focus in finding solutions for pollution control and replacement of non-biodegradable products with natural products. In this matter, composite materials with natural fibres are increasingly interesting for different research studies. The present work regards a flax fibre-epoxy resin composite material, which the response is studied under tensile tests until break and repeated loading/unloading cycles. An independent variable under study has been material fibre direction of 0°, 90° and ± 45°, for both types of tests. Samples were extracted from thermo-compression fabricated plates with dimensions following the ASTM D 3039 standard. The experimental setup included an MTS C45 105 Universal Testing Machine, with variable load cells, an extensometer, as well as digital image correlation equipment. The devices allowed the determination of stressstrain curves as well as material constants and Poison ratio. Results show, for the 90° and ± 45° typical responses for composites with these fibre directions, but a particular evolution, bilinear for the 0°.
Aspects of the wheel-switch contact studied with the CONTACT software
Authors: Tudorache M C , Dinu V M , Oprea R A 
Published: January 2021

Abstract
The rapid variation of the wheel and rail profile influences, on one hand, the grip-pseudo-slip - wear characteristics, and on the other hand, the dynamic behavior of the vehicle, because the pseudo-slip forces are significantly influenced by the contact area and pressures from within this area. It must be borne in mind that, in most cases, the rail-road has deviations from the geometric dimensions, which must not affect traffic safety and the demands of the running gear and the track must be within the permissible limits. Railway switches ensure discontinuities on the railway causing high dynamic loads. In operation, the rail-way devices must ensure three basic requirements: safety against derailment, stability while on the move and passenger comfort. In this context the paper presents aspects of the multipoint wheel-rail-way switch contact using the Contact software. Considering the influence of sliding speeds on the contact phenomena at the intersection of the wheel with the running path, the paper presents an analysis of the kinematic behavior of the axle while passing over a point rail.
Optimal selection of milling cutting tools for machining of triangular pockets
Authors: Belloufi A , Abdelkrim M , Rezgui I , Saci R , Mezoudj M , Amira M T 
Published: January 2021

Abstract
Minimizing machining time is an objective that must be taken into account when choosing the cutting tool. The diameter of the cutting tool is one of the parameters which greatly influences the machining time of different geometric shapes, especially pockets. In this study, a methodology for optimizing the choice of milling cutting tools for machining triangular pockets was proposed. An analytical model expressing the length of cutting tool paths has been optimized using sequential quadratic programming. the study carried out in this work leads to the conclusion that the spiral contour strategy makes it possible to have a minimum length for the machining of triangular shaped pockets.
Application of software solution for solving engineering design optimization problems
Authors: Madic M , Janković P , Trifunović M , Kovacević M 
Published: January 2021

AbstractEngineering design problems involving a set of continuous, discrete and integer design variables and complex, non-convex objective functions and linear and non-linear constraints represent optimization problems with considerable complexity which are not trivial to solve. In recent years a number of optimization methods, particularly meta-heuristic optimization algorithms, were highlighted as effective optimization tools to deal with this type of engineering design problems. Despite certain advantages, their stochastic nature may be insufficient in dealing with various kinds of variables, constraints and objective functions. This paper discusses the application of developed software solution for solving engineering design optimization problems which is based on deterministic approach, i.e. the use of exhaustive iterative search algorithm. The use of the developed software solution is validated using four standard engineering design problems reported in the referential literature. In all case studies, the determined optimization solutions are equally good or better than those reported from other researchers using algorithms representative of the state-of-the-art in the area.
Analysis and development of a key performance indicators model for the paper industry
Authors: Tieber A , Manolache D , Gheorghe M 
Published: January 2021

Abstract
It is advisable to implement the use of key indicators by each company as a support for its continuous performant activity. Massive potential for optimisation can be found in the whole production industry. A scientific survey study has been designed and addressed to a number of companies from production industry in Europe. In the framework of this survey, the paper industry, as part of production industry, has been more profoundly analysed, in order to find the level of understanding and use of the key performance indicators and KPI systems, as an example. Based on the elements revealed by this analysis, a KPIs - Model for processes, production, financials, quality, supply chain, human resources and innovation is developed. This KPIs - Model can be a basis for the development of further KPIs - Models by any interested company, based on its specific conditions.
Comparative analysis of the reliability of electric locomotives based on semi-Markov models of restorable systems
Authors: Dyshin O A , Sh Pashayeva K , Aslanov C G 
Published: January 2021

AbstractBased on the general theory of semi-Markov recovery processes and their application to Markov recovery processes, the applicability of stationary reliability indicators to assessing the reliability of electric locomotives with an asynchronous motor, the functioning of which is considered as a superposition of independent alternating semi-Markov processes, is shown. By calculating the main indicators of system reliability in a steady state, a comparative analysis of the operational reliability of electric locomotives with an asynchronous DC and AC motors, used respectively on the Azerbaijan and Kazakhstan railways, was carried out.
Prospects of introducing alternative sources of energy on Ukrainian railways
Authors: Panchenko V V , Masliy A S , Kharin R O 
Published: January 2021

Abstract
The potential of solar and wind energy was investigated, the existing premises of using the electric power obtained from non-conventional power sources of non-traction consumers for power supply of an electric traction system were analyzed. The influence of solar generation sources connected with the traction substation tires on the stability of non-traction consumers was determined. Possible options of connecting renewable energy sources to the railway power systems were examined. Calculations for determining the number of solar panels for compensating the auxiliary power consumption of the traction substation were made. The modeling of the possibility of implementing alternative energy sources in a traction substation in the PVsyst program was carried out. In Ukraine, the change of conditions for the provision of electricity supply services was caused by the rapid growth and development of renewable energy sources, in connection with which the number of suppliers increased. The question about the possibility of using alternative electricity sources to compensate the auxiliary power consumption of traction substations arises. Therefore, it is relevant to solve the problem of joint work of auxiliary power consumers together with non-traditional energy sources. The auxiliary power consumption of the traction substation include: heating drives and tanks of transformers; cooling down trip coils, relays, control panels, alarm systems, alarm and centralization and blocking devices; heating substation premises, store rooms and shower room. In order to implement alternative energy on the railway, it is necessary to analyze the auxiliary power consumption of the traction substation; to analyze the possibility of placing alternative power sources on the traction substation premises; to investigate how the powering system of the auxiliary power consumption of the traction substation can operate (both directly and in parallel mode).
Scientific approach to fire resistance calculation of reinforced concrete beams and columns
Authors: Fomin S L , Bondarenko Y V , Butenko S V , Koliesnikov S M 
Published: January 2021

Abstract
Problems related to the fire resistance calculation of reinforced concrete beams and columns from a scientific point of view when using new design standards are considered. The first problem is the insufficient development of improved calculation methods, exactly their absence. Only basic principles and requirements are formulated for them. This article presents the principles and sequence of calculation. The second problem is the lack of an accurate mathematical nonlinear compression model of the stress-strain diagram for concrete. The article explains the imperfection of the existing one, the need to create a new model and presents the basic requirements that such a mathematical model must meet. The third problem of the discussed ones is the erroneous values of the relative ultimate deformation of concrete. The principle of formation of values of relative limiting deformation of concrete is specified and proceeding from it the additional requirement for mathematical nonlinear model of compression of the diagram of stress - strain for concrete is specified.
Physicochemical studies of the structure of energy-saving compositions based on slags
Authors: Kostyuk Tetyana , Vinnichenko Varvara , Plugin rii , Borziak Olga , Iefimenko Artem 
Published: January 2021

Abstract
Blast furnace slags are subdivided into granular and dump. Granulated slag is widely used in the construction industry to production of Portland cement, Portland slag cement, slagalkaline cements, and concretes based on these cements. Dump slag is of less use, because it has low activity. The phase composition of granular and waste slag was investigated by methods of physicochemical analysis. The slags contain minerals that are present in Portland cement clinker. Concrete samples were made using granular, waste slag and sand. Unsatisfactory results in compressive and flexural strength were shown by a sample made of only two types of slag. The best strength results were obtained for a composition in which there are three components: granular slag, dump slag (filler) and sodium hydroxide. Electronic images have confirmed the appearance of low-basic calcium silicates, which provide the strength of the cementless composite. The resulting concrete composition is resource-saving, because made from production waste. And it can be called energy-saving, because no energy is expended to obtain components. The ecological feasibility of the production of such concrete is due to the absence of emissions of pollutants into the atmosphere (including carbon dioxide), since the firing of cement clinker is not needed.
Resource-saving steel hopper for loading of railway cars
Authors: Makhinko Anton , Makhinko Nataliia 
Published: January 2021

Abstract
The article is devoted to the study of geometric characteristics of corrugated sheets of railway grain hopper. In particular, the problem of finding the optimal parameters of a corrugated sheet of a given length, such as the height and width of the corrugation shelves, is solved. The optimality condition in this problem is determined by the minimum mass of the corrugated sheet. Because of analytical calculations, it was found that, regardless of the angle of tip of the corrugation wall, there will always be such a value of optimum height at which the corrugation area will be the smallest. For the analysis of this parameter, a series of curves of dependence of the corrugation cross-section area on the height for different angles of tip were constructed. The study also provided concise and engineering-friendly equations to determine the optimum height and width of corrugation shelves for wall angles up to 60º. These expressions can be applied to the case of corrugated sheet with a limited number of erection joints. For other cases of jointing of the corrugated sheets with each other (complete or partial overlapping of the lower part), additional studies should be performed similar to the procedure presented.
Management of the technical condition of hydraulic structures
Authors: Makovetsky B I , Sankov P M , Papirnyk R B , Tkach N O , Trifonov I V 
Published: January 2021

Abstract
In the process of operation of hydraulic structures it is needed to study these structures for their technical condition, which affects the durability and other structures operational properties. Some defects are impossible or difficult to examine. This is due to the lack of open access for visual inspection. Such defects are cavities formed under reinforced concrete slabs, which protect the dam from erosion. Timely detection and elimination of cavities during repairs extends the service life of dams. Scientifically confirmed methods are proposed, by means of which the problem of finding the location and the volume of cavities under reinforced concrete of ground dams, dams and other hydraulic structures is solved. The research proves that with using the natural pulsed electromagnetic field of the Earth geophysical method it is possible to interpret in terms of the cavities which occur during the inspection of the reinforced concrete fastening of the upper slope of the dams. The authors propose to determine the depth of anomalies by the color of the equal level of the natural pulsed electromagnetic field of the Earth, which corresponds to the depth of the cavities obtained by the method of geoelectric tomography.
General model and the mechanics of concrete elements and structures deformation
Authors: Romashko V M 
Published: January 2021

Abstract
The article presents a critical analysis of the model development of reinforced concrete elements and structures resistance by force influences. Their relationship with the defining provisions of the mechanics of reinforced concrete elements deformation was evaluated. The main disadvantages of the models considered are identified. A universal deformation and force model of deformation of reinforced concrete elements and structures is proposed, which is free of most of the disadvantageous characteristic of other models. The main advantage of the deformation-force model of resistance is indicated, due to the expansion of the known system of static, geometric and physical relationships to the level of statically definable. It becomes noticeable when calculating reinforced concrete elements and structures for deflection and crack resistance. This is one of the main features of the deformation-force model, which makes it possible to quite simply “embed” the technical theory of reinforcement to concrete adhesion into the general theory of reinforced concrete deformation. Due to the averaged design cross-section and the averaged materials deformations in the block between cracks, all parameters of cracks formation and propagation in the deformation-force model are directly related to the parameters of reinforcement to concrete adhesion.
Theoretical basis of bearing capacity calculation of the statically indeterminate reinforced concrete beams and its experimental research
Authors: Shkurupiy A A , Mytrofanov P B , Davydenko Yu O , Horb A G 
Published: January 2021

Abstract
New normative documents of Ukraine for the design of reinforced concrete and their elements contain a number of fundamentally new approaches to the calculation of their bearing capacity. Deformation model with an empirical criterion of durability is accepted as a basis of calculations of concrete and reinforced concrete elements on action of bending moments and longitudinal forces. Statically indeterminate reinforced concrete structures, in particular fixed beams, are widely used in various buildings and structures as load-bearing structures. Therefore, the research of their work and the direct calculation of such structures on the basis of the deformation model is a very important issue in the current trend of development of reinforced concrete both in our country and abroad. Theoretical calculations of bearing capacity of reinforced concrete continuous beams on the basis of deformation model with extreme strength criterion with the use of optimization and numerical methods and the limiting equilibrium method are performed. Their experimental studies are carried out. The results of theoretical calculations of such constructions are compared with experimental data obtained by the authors of the article and given in the works of other researchers.
Reinforcement of a deformed structure on the pile foundation
Authors: Vynnykov Yu L , Kharchenko M O , Manzhalii S M 
Published: January 2021

Abstract
The results of geomonitoring of the technical state of a five-storeyed building erected on driven prismatic piles are presented. The cause of excessive deformations of the foundation base is the inability of the pile tip to reach the design depth, which led to a significant reduction in their load-bearing capacity. The constructive technological solution of strengthening of the bases from piles as a part of a tape grid by bringing under existing grids of a monolithic reinforced concrete slab is improved. A new analytical model of the system “deformed building – driven prismatic piles as a part of a tape grid – soil base with a weak underlying layer” before and after supplying the slab under the existing foundation grids. The stress-strain state (SSS) of this system is estimated using the finite element method (FEM). New data of the change in the SSS system after supplying the slab under the existing grids were obtained. The results of the project execution (without resettlement of the residents of the house) and the respective geomonitoring are presented.