Formation Of Internal Structure Research Articles

Structure and Properties of PBS/PBAT blends and nanocomposites

The use of bio-compostable polymers such as Polybutylene Succinate (PBS), Polybutylene Adipate Co-Terephthalate (PBAT) or Polylactic acid is restricted due to the barrier properties especially the water vapor transmission rate (WVTR) which is high in these commercially available polymers. The WVTR plays an important role in preserving the freshness of fruits and vegetables and it has to be optimum. Polymer blending and incorporation of nano fillers are facile routes to formation of internal structure and morphology which gives good control of barrier properties of films. Hence, crystalline structure and morphology of PBS-PBAT blends were studied in detail with respect to composition of the blend. The effect of nanofillers (Halloysite nanotubes/HNT) incorporation as well as addition of polyethylene glycol (PEG) as plasticizer on crystallization process was also investigated. The samples were cast on a glass plate substrate from solution using membrane caster at constant speed and thickness in the range of 100 microns. The composition was varied from 0 to 40 % of PBS in PBAT matrix while addition of HNT was varied from 1 to 5%. Films were air dried in an oven at 50-55 °C for 6 hr. The crystal structure development was studied using wide angle X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC) and the molecular interaction examined using FTIR. XRD data indicated that PBS crystals were in monoclinic α phase but the relative intensities of the 011 and 020 reflections changed drastically in the blends. The DSC analysis revealed that there was preferential growth of PBS α phase crystals with sharp melting at 110 °C. The HNT gave distinct nucleation effect with a shift in the Tc peak as well as increase of ΔHc value. The preferential nucleation by HNT could be associated with the close lattice match for the HNT and the monoclinic phase of PBS. FTIR studies indicate that the all the contents were dispersed well and show hydrogen bonding interaction at the –OH and –COOH groups. These changes in the crystallinity and crystal phase improved the barrier properties leading to the decrease in (WVTR) with the addition of PBS to PBAT as well as incorporation of HNT in the blend. WVTR decreased from 120 g/m2/day to 55 g/m2/day which is excellent for packaging of green agriculture produce.

Theoretical and methodological model of criminalistics and its new directions

This research paper purpose is to find out tendencies of development of criminalistics in globalized world, define its borders, forecast emergence of new directions and to characterize them.
 Theoretical and methodological model of criminalistics is studied, tendencies and specifics of formation of criminalistics in modern conditions are traced.
 Formation of internal structure of criminalistics (its system) is considered, connection with other sciences (natural sciences, humanities, social, formal) is determined, relationship with forensic sciences (forensicmedicine, forensic toxicology, forensic psychology, forensic chemistry, etc.) and forensic expertology is established. Attention is drawn to the orientation of the forensic vector of Ukraine to a single forensic European space. Necessity of creating a new section in the structure of criminology, namely: forensic strategy is substantiated.
 Origin specifics, formation and development of new branches (directions) of criminology are considered: competitive, judicial, medical, genotypic, aerospace, computer (digital) and nuclear ones. Necessity of using forensic knowledge by different parties in criminal proceedings both in while of pretrial investigation and in legal proceedings is argued. The subjects of specific expertise application of forensic knowledge should be not only the investigator, but prosecutor, investigating judge, interrogator, detective, judge, lawyer.
 Emergence of new branches of criminology is associated with scientific and technological progress, the emergence of new technologies, the need to work with specific traces and complexity of collecting and examining evidence. Special attention is paid to development and formation of medical, digital and nuclear forensics.

Ceramics composites from iron ore tailings and blast furnace slag

The search for materials and methods capable of reducing human impacts on the environment is of utmost importance nowadays. This study's primary purpose was to analyze the technical feasibility of ceramic composites production utilizing Fundão Dam's Iron Ore Tailings (IOT), Blast Furnace Slag (BFS) from charcoal, and Foundry Sand (FS) as partial substitutes for the traditional raw materials – sand and clay – for application in building industry materials. The composites were molded in rectangular specimens and fired at temperatures of 900, 950, 1000, 1050, and 1200 °C. The developed materials were analyzed and characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Thermogravimetry (TGA), and Differential Thermal Analysis (DTA). The obtained materials had flexural strength modulus of up to 12.19 MPa, water absorption ranging from 2 to 22%, linear shrinkage ranging from 0.02 to 6.50%, and apparent density ranging from 2.03 to 1.63 g/cm3. The study of the internal structure formation process revealed the formation of amorphous structures in the composites. The results demonstrated that these waste materials may be jointly used in construction materials, contributing to the reduction of natural resource extraction, besides enabling their correct disposal, minimizing environmental impacts, and improving the life quality of the surrounding communities.

Study of internal porous structure formation of the powder metallurgically prepared aluminium foam

The internal pore wall structure formation and density play an important role in improving the mechanical and thermal properties of the closed-cell aluminium foams. The present research work aims to investigate the internal structure formation of the aluminium foam prepared by powder metallurgy and the uniformity of the distribution of the pores when the minimum amount of TiH2 is added. The foamable precursor of two different aluminium alloys (Al-1050 and A5083) is produced with a TiH2 gaseous agent of 0.05 wt.%. The parameters analysed include the density, pore wall formations, pore, and metal density distribution inside the structure with the help of X-ray tomography. Furthermore, the image-processing technique has been adopted to produce the 3D surrogate model of the foam for visual inspection and analysis. The obtained results show the importance of the amount of TiH2 addition and of the foaming furnace temperature in deciding the internal porous structure formation. Further, the pore morphology of lower porosity foams (in the range of 30-40 % porosity) of the two alloys produced at 690 °C furnace temperature is investigated with the help of developed surrogate models. The presence of micropores and uniformity of the distribution of pores found brings the idea of choosing the optimized structure of foam for thermal energy storage systems associated with PCM.

Influence of Freezing Parameters on the Formation of Internal Porous Structure and Its Impact on Freeze-Drying Kinetics

The main objective of this study was firstly to investigate the influence of freezing process parameters on the formation of the internal structure of frozen coffee granules. It was investigated how these frozen internal structures affect the drying kinetics during freeze-drying. A design of experiment study was carried out using the response surface method to quantify the influence of the freezing step that occurs in a scraped surface heat exchanger (SSHE). Therefore, the coffee extract at a concentration of 30% w/w is entering the SSHE as a liquid and gets partially crystallized up to a weight-based ice content of 0.364. During this step, the influence of factors like cooling temperature, scraper rotation speed and temperature cycles on ice crystal structure was investigated. In a second freezing step, the influence of freezing rates during hardening of the product by air-blast freezing is investigated, where the freezing rate is significantly affected by the cake thickness. The produced frozen granules were freeze-dried in single layer experiments. During drying the influence of internal structure on the drying kinetics was investigated. Results show that all factors have a significant impact on structure parameters for 30% w/w coffee solutions. A lower degree of supercooling during freezing in an SSHE, a higher number of temperature cycles (2 to 8 times) and lower freezing rates during hardening (2 °C/min to 10 °C/min) were leading to increased crystal size. This increase accelerates the primary drying rate and decreases the total drying time. A higher number of temperature cycles leads to a significant increase of crystal size and therefore larger pore size at the end of the primary drying. Furthermore, in combination with temperature cycles in the SSHE, it was found that high freezing rates during air blast freezing generally lead to a second nucleation step of ice crystals.

Two-layer channel flow involving a fluid with time-dependent viscosity

A pressure-driven two-layer channel flow of a Newtonian fluid with constant viscosity (top layer) and a fluid with a time-dependent viscosity (bottom layer) is numerically investigated. The bottom layer goes through an ageing process in which its viscosity increases due to the formation of internal structure, which is represented by a Coussot-type relationship. The resultant flow dynamics is the consequence of the competition between structuration and de-structuration, as characterised by the dimensionless timescale for structuration \((\tau )\) and the dimensionless material property \((\beta )\) of the bottom fluid. The development of Kelvin-Helmholtz type instabilities (roll-up structures) observed in the Newtonian constant viscosity case was found to be suppressed as the viscosity of the bottom layer increased over time. It is found that, for the set of parameters considered in the present study, the bottom layer almost behaves like a Newtonian fluid with constant viscosity for \(\tau >10\) and \(\beta >1\). It is also shown that decreasing the value of the Froude number stabilises the interfacial instabilities. The wavelength of the interfacial wave increases as the capillary number increases.

Preparation, properties characterization and structure formation mechanism of silica sand tailings-based ceramic materials

The preparation of high-performance ceramics using industrial waste as raw materials is an important direction in the comprehensive utilization of waste residue. In this paper, we used silica sand tailings and other industrial waste as raw materials to prepare two types of full waste-based ceramic materials without additional agent. The results showed that different waste ratios caused the variation in content and composition of glassy phase formed in the full waste-based material, leading to the formation of internal structure in different ceramic materials. Especially, the composition of glassy phase formed in ceramic foams was transferred from Ca–Al–Si–O to Al–Si–O glass system, resulting in the difference in pore structure and performance. This work provides a way to design the composition and control the properties of materials by using coupling reactions between chemical components during the material preparation, achieving high value, high efficiency and safe use of waste resources.

Photocatalytic activity of magnetic core-shell CoFe2O4@ZnO nanoparticles for purification of methylene blue

Magnetic core–shell CoFe2O4@ZnO nanoparticles have been successfully synthesized by using coprecipitation method to provide easy separated nanomaterials and high photocatalytic activity performance. Core–shell nanoparticles with various CoFe2O4-to-ZnO molar ratio (1:2, 1:3, 1:4, 1:5) have been investigated over x-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible spectroscopy, and vibrating sample magnetometer. XRD spectra confirm the cubic spinel ferrite phase structure of CoFe2O4 and the hexagonal wurtzite phase of ZnO. The crystallite size is found within the range of 14.9–20.6 nm. TEM measurement confirms the good crystallinity of the samples. The magnetic hysteresis shows that CoFe2O4@ZnO has high saturation magnetization of about 30 emu g−1 and coercivity of about 300 Oe. Photocatalytic investigation was carried out using methylene blue (MB) under UV irradiation. Our result yields the enhancement of MB degradation as ZnO content increases. The maximum photodegradation achieved by the core–shell nanoparticles is 57.2%, 60.5%, 65.5%, and 78.3% for molar ratio of 1:2, 1:3, 1:4, and 1:5, respectively. The enhancement of MB degradation can be attributed to the formation of internal structure between CoFe2O4 and ZnO in the form of heterojunction structure. The magnetic properties of core–shell lead to the easy separation between the magnetic core–shell nanoparticles and the final degraded solution by permanent magnet.

Impact of high-energy effects on the formation of internal structure in copper particles

In the present paper, results of a study of the impact of high-energy effects on the surface morphology and on the formation of the internal structure in PMS-1 copper particles are reported. It is shown that the mechanical milling of the copper powder in a planetary mill leads to the formation of powder agglomerates with a layered structure consisting of numerous deformed ultrafine particles. It is found that the volume of the agglomerated particles involves the defects in the form of microcracks and closed micropores with some content of the initial gas. Subsequent treatment of the powder in an argon-helium plasma jet leads to the formation of dense particles as well as particles with distributed gas volumes or a single cavity. It was found that, as the molten metal interacted with localized gas volumes during the plasma treatment, local oxidation of the material occurred. A dispersion-strengthened structure with copper oxide compounds of a predominantly round shape, ranging in size from tens of nanometers to 7 µm and uniformly distributed over the particle volume, was formed.

Microwave-assisted synthesis of l-histidine capped silver nanoparticles for enhanced photocatalytic activity under visible light and effectual antibacterial performance

A facile, rapid one-step green strategy is established here to prepare the l-Histidine (His) capped silver nanoparticles (His-AgNPs) using microwave irradiation conditions performed for optimal duration of 5 min. For the prepared His-AgNPs have been characterized by X-ray powder diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), high-resolution scanning electron microscopy (HR-SEM), Zeta potential measurements and high-resolution transmission electron microscopy (HR-TEM), Energy dispersive X-ray spectroscopy (EDX) and UV–Vis spectroscopy techniques also. The HR-SEM images have exposed that flake-like internal structure formation of His-AgNPs with sort nanometer-sized spherical shape morphology has attained. As well, studies prove that, the antibacterial activities of synthesized His-AgNPs had a significant performance against various G+ and G− bacteria. Then, the photocatalytic actions of His-AgNPs seem to contain sustaining degradation of MB and MO aqueous dyes under visible light exposure. Overall, the 98% of cationic MB dye degraded within 40 min and 97% anionic MO dye degraded within 100 min of photocatalytic irradiation. The probable mechanism for the improved photocatalytic assets of the His-AgNPs is also discussed. Hence, this study validated a simple and economical approach to synthesize His-AgNPs that are potential candidates for various highly useful industrial and packaging applications.

The assessment of the structural changes of fine-grained cement-based composites in the early-age using acoustic testing

The paper deals with the monitoring of the structural changes of fine-grained cement-based composites in the early-age using acoustic emission method. After mixing, the cement-based materials exhibit continuous time-dependent structural changes which lead to the changes in the mechanical properties due to the chemical and physical processes. The events which are emitted due to the internal structure formation were detected using the acoustic emission techniques. A number of AE events are released due to the formation of new crystalline phases and due to microcracking in the material structure during the setting and hardening. The aim of the performed experiments was to extend the knowledge in the field of the early-age material characteristics and in the field of the internal structure formation of the cement-based materials. The results from temperature measurement show that mixture with microsilica has more slowly raised the internal temperature than mixture without microsilica. The results from acoustic emission measurement show that mixture with microsilica has lower activity of acoustic emission than mixture without microsilica during first six hours from measurement start.

Explaining the Natural Materials of Traditional Kitchen Appliances In the Javanese Coastal Communities Based on Internal Structure Formation of Lingual Units

The purpose of this study is to describe the traditional kitchen appliances used by Javanese women. This explanation is based on deciphering its shape and structure, and semantic deciphering. The natural materials used are always environmentally friendly and have a trustworthy charge that can be delivered transparently or clandestinely, The research method used was descriptive qualitative. The methods of collecting the used data were observation, and in-depth interviews. The method of research analysis was by decomposing the lingual unit component of the traditional kitchen lexicon compiler from the derivative word into a basic form by utilizing the technique direct divide elements in the units of form and meaning. The findings of the research are the rules of forming lingual units for traditional kitchen appliances from the basic forms to derivative forms. The rules of formation in the word formation are produced by lexicon reconstruction, while the rules of formation in the meaning field are generated by semantic developers originating from coastal culture. The description of natural material based on the analysis of the internal structure of lingual units is obtained by the coherence of circular relations: sign-concept-functions-cultural values-sign.

Image processing procedure to quantify the internal structure of porous asphalt concrete

PurposeIn order to fully understand the properties of porous asphalt, investigation should be conducted from different point of views. This is from the fact that porous asphalt mixture designed with the same aggregate gradation and air void content can give different infiltration rate due to the different formation of the internal structure. Therefore, the purpose of this paper is to investigate the micro-structural properties and functional performance of porous asphalt simultaneously.Design/methodology/approachThe aim is to develop imaging techniques to process and analyze the internal structure of porous asphalt mixture. A few parameters were established to analyze the air void properties and aggregate interlock within the gyratory compacted samples captured using a non-destructive scanning technique of X-ray computed tomography (CT) throughout the samples. The results were then compared with the functional performance in terms of permeability. Four aggregate gradations used in different countries, i.e. Malaysia, Australia, the USA and Singapore. The samples were tested for resilient modulus and permeability. Quantitative analysis of the microstructure was used to establish the relationships between the air void properties and aggregate interlock and the resilient modulus and permeability.FindingsBased on the results, it was found that the micro-structural properties investigated have successfully described the internal structure formation and they reflect the results of resilient modulus and permeability. In addition, the imaging technique which includes the image processing and image analysis for internal structure quantification seems to be very useful and perform well with the X-ray CT images based on the reliable results obtained from the analysis.Research limitations/implicationsIn this study, attention was limited to the study of internal structure of porous asphalt samples prepared in the laboratory using X-ray CT but can also be used to assess the quality of finished asphalt pavements by taking core samples for quantitative and qualitative analysis. The use of CT for material characterization presents a lot of possibilities in the future of asphalt concrete mix design.Originality/valueBased on the validation process which includes comparisons between the values obtained from the image analysis and those from the performance test and it was found that the developed procedure satisfactorily assesses the air voids distribution and the aggregate interlock for this reason, it can be used.

Investigations on the joint properties of the friction welding of aluminium alloy tube to tube plate using an external tool

Purpose: Aluminium and its alloys are frequently used in structural applications due to their good welding ability as well as their high strength and corrosion resistance. Several developments have been observed on the welding of aluminium in last decade. The manufacturing of heat exchangers, economizers and boilers is highly cost progress due to tube to tube plate welding’s. The purpose of this study is investigation of friction weldability of tube to tube plate aluminium alloys using an external tools (FWTPET) which is a relatively newer solid state welding process used for joining tube to tube plate. Design/methodology/approach: First, preliminary experiments were carried out to determining suitable the tool rotational speed, pressure load and temperature. An experimental setup has been designed and manufactured to keep the pressure load constant during the preliminary tests. Then, by changing the weld mouth on the plate, the gap between the tube and the plate, and the tube projection parameters, the effects of all parameters on shear strength values, micro hardness values and the formation of internal structure of the weld zone were investigated. Findings: It was founded that aluminium tubes can successfully weld to tube plates with using an external tools. Also it is seen that vertical force between tool and sample, tube protection and temperature are very important parameters which are effect of welded joint properties. Practical implications: FWTPET which is new welding method has been used in industrial field in last few years. Originality/value: In the beginnings studies concentrate on non-ferrous metals such as Al, Cu, Mg etc. So this studies on FWTPET have remarkable importance.

Prediction and evaluation of density and volume fractions for the novel perlite composite affected by internal structure formation

Mechanism of internal structure formation of perlite composite foams due to compaction is identified. Foam and particle envelope densities, and volume fractions are theoretically modelled for prediction and practical evaluation. The volume fractions, as functions of manufacturing variables, include those affected by topological change of internal structure of foam after compaction process, consisting of binder, perlite material, porous zone of original particles, debris zone, and inter-particle voids. Predictions were validated against directly measured values for foam and particle envelope densities. A problem with the conventional method for obtaining volume fraction of binder is analytically addressed in terms of error sensitivity. Values for volume fraction of binder obtained from the conventional method were found to have errors up to about 300% (or about three times validated one). An example is given to show how the predictive models can be used for optimisation of manufacturing and properties. Applicability of formulas based on the new evaluative method is also shown for syntactic foams. Experimental results were obtained from a foam density range of 0.16–0.50g/cm3 and a porosity range of 0.79–0.93 for expanded perlite particle sizes between 3 and 4mm, a compaction ratio range of 1–3.56, and a pure sodium silicate content range of 0.05–0.35g/ml in dilution of water for binder.

Formation of internal structure in the rolling of a bcc (110)[001] single crystal

The stages of structure formation during cold rolling are investigated in bcc (110)[001] single crystals of Fe–3% Si alloy, within the deformation zone. To obtain a visible deformation zone, the laboratory mill is abruptly stopped at the instant of sample rolling. To reduce the frictional coefficient, lubricant is used for some of the samples. The deformational structure is studied by metallography and orientational electron microscopy (EBSD). Deform-3D software is used to analyze the relation between the experimental data and the calculated stress state in rolling, for various values of the frictional coefficient. Depending on the frictional coefficient, the stress state may significantly affect the mesostructure formation and the texture development. In a single crystal rolled with elevated friction, when the deformation is relatively small, deformation bands are formed. Orientational analysis of the contact point of deformation bands reveals alternating microbands, each with slight different orientation, which are separated by small-angle boundaries. In the rolling of a (110)[001] single crystal with lubrication (reduced friction), twinning is observed even with slight deformation. The twinning is evidently due to the reduced contribution of surface energy to the total energy of twin nucleation. Throughout the whole deformation process, either the twins of both systems retain the strict Σ3 crystallographic relation with the matrix or else, on account of the local lattice reorientation, Σ3 disorientations are converted to similar special Σ17b and Σ43c disorientations. On the basis of experimental data, a dislocation model is proposed for the formation of deformational mesostructures in the cold rolling of a (110)[001] single crystal. This model includes the formation of microbands in the initial stage of deformationband generation; the formation of transition bands parallel to the rolling plane with the dynamic retention of the initial orientation; and the formation of transition bands inclined to the rolling plane with a habitus parallel to the {112} matrix plane. These inclined planes are equivalent to shear bands whose habitus is inclined at ~17° to the rolling plane.

Effects of varying obliquity on Martian sublimation thermokarst landforms

Scalloped depressions in the Martian mid-latitudes are likely formed by sublimation of ice-rich ground. The stability of subsurface ice changes with the planetary obliquity, generally becoming less stable at lower axial tilt. As a result, the relative rates of sublimation and creep change over time. A landscape evolution model shows that these variations produce internal structure in scalloped depressions, commonly in the form of arcuate ridges, which emerge as depressions resume growth after pausing or slowing. In other scenarios, the formation of internal structure is minimal. Significant uncertainties in past climate and model parameters permit a range of scenarios. Ridges observed in some Martian scalloped depressions could date from obliquity lows or periods of low ice stability occurring <5 Ma, suggesting that the pits are young features and may be actively evolving.

The possibility of using phase transition in Ni and Cu nanoclusters for information recording processes

The opportunity of transition metals nanoclusters’ usage as a data bits in memory devices for the recording transition “order-disorder” has been analyzed. Therefore, with the help of the molecular dynamics method on the basis of TB-SMA potential the simulation of metal nanoparticles (D = 1.6 - 5.0 nm) crystallization processes have been studied. Influence of various conditions of crystallization on formation of internal structure in metal nanoclusters is investigated. The stability boundaries of various crystalline isomers are analyzed. The obtained dependences are compared with the corresponding data obtained for copper and nickel nanoparticles having similar sizes. The limiting size of nanoparticles is determined, for which a structural "order-disorder" transition necessary for the data recording is still possible.

Two‐dimensional modeling of polymer wet spinning: The effects of mass transfer dynamics on structural properties

ABSTRACTIn this work, a two‐dimensional model of polymer wet spinning that couples simultaneous momentum and energy transport with ternary diffusion and phase separation processes is presented and its predictions for a model system are discussed. The uniqueness of the model lies in its two‐phase nature and ability to predict important characteristics of the wet spinning process, such as the locking‐in of axial velocity, mass transfer behavior, and internal structure formation along the spinline. The model predicts growth of the two‐phase gel that forms and the porous fractions within it, along with the compositions of the polymer‐rich and solvent‐nonsolvent‐rich phases. The appearance of a skin‐core structure that depends on the system and operating conditions is also predicted. These features are demonstrated through analyses of the isothermal wet spinning of poly(acrylonitrile) solutions in dimethlysulfoxide using two different nonsolvent coagulants, water and ethanol. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41772.

The estimation of possibility of using order-disorder transition phenomena in Ni, Cu and Au nanoclusters for advancing the efficiency of information recording processes.

The opportunity of transition metals nanoclusters' usage as a data bits in memory devices for the recording transition "order-disorder" has been analyzed. Therefore, with the help of the molecular dynamics method on the basis of TB-SMA potential the simulation of metal nanoparticles (D = 1.6-5.0 nm) crystallization processes have been studied. Influence of various conditions of crystallization on formation of internal structure in metal nanoclusters is investigated. The stability boundaries of various crystalline isomers are analyzed. The obtained dependences are compared with the corresponding data obtained for gold, copper and nickel nanoparticles having similar sizes. Nickel and copper clusters are shown to exhibit common features in the formation of their structural properties, whereas gold clusters demonstrate much more complex behavior. The limiting size of nanoparticles is determined, for which a structural "order-disorder" transition necessary for the data recording is still possible.