Assessment of the Influence of Fabric Structure on Their Electro-Conductive Properties.

Electro-conductive fabrics are key materials for designing and developing wearable smart textiles. The properties of textile materials depend on the production method, the technique which leads to high conductivity, and the structure. The aim of the research work was to determine the factors affecting the electrical conductivity of woven fabrics and elucidate the mechanism of electric current conduction through this complex, aperiodic textile material. The chemical composition of the material surface was identified using scanning electron microscopy energy dispersion X-ray spectroscopy. The van der Pauw method was employed for multidirectional resistance measurements. The coefficient was determined for the assessment of the electrical anisotropy of woven fabrics. X-ray micro-computed tomography was used for 3D woven structure geometry analysis. The anisotropy coefficient enabled the classification of electro-conductive fabrics in terms of isotropic or anisotropic materials. It was found that the increase in weft density results in an increase in sample anisotropy. The rise in thread width can lead to smaller electrical in-plane anisotropy. The threads are unevenly distributed in woven fabric, and their widths are not constant, which is reflected in the anisotropy coefficient values depending on the electrode arrangement. The smaller the fabric area covered by four electrodes, the fewer factors leading to structure aperiodicity.

Internal Adaptation of Composite Fillings Made Using Universal Adhesives-A Micro-Computed Tomography Analysis.

This study aimed to evaluate internal tooth-filling interfaces of composite fillings made using universal adhesives using micro-computed tomography (µCT). Sixty class V cavities were randomly assigned into six groups: Peak Universal etch and rinse (PER), Peak Universal self-etch (PSE), Adhese Universal etch and rinse (AER), and Adhese Universal self-etch (ASE). Two further adhesives considered gold standards were used as control groups: OptiBond FL (OER) for the etch and rinse technique and Clearfil SE for the self-etch technique (CSE). All teeth were subjected to thermomechanical loading and four-year water storage. Next, they were analyzed using µCT to investigate the internal tooth-filling interfaces. The proportions between the gap volume (GV) at the tooth-filling interface and the volume of applied composite filling (FV), between the gap and cavity volumes (CV), and between the gap volumes at the tooth-filling interface of the external (EGV) and internal (IGV) parts were calculated. Adhese Universal achieved the significantly lowest gap-to-filling- and gap-to-cavity-volume ratios for both types of etching techniques comparing to those of the Peak Universal and control groups. Significant differences between the gaps in external and internal parts of the tooth-filling interface were only noted in the control groups. Internal gap formation and development at the tooth-filling interface depend on the material as well as the type of its application.

Investigation of the Hydrolytic Degradation Kinetics of 3D-Printed PLA Structures under a Thermally Accelerated Regime.

The application of biobased and biodegradable polymers, such as polylactide (PLA), in fused deposition modeling (FDM) 3D-printing technology creates a new prospect for rapid prototyping and other applications in the context of ecology. The popularity of the FDM method and its significance in material engineering not only creates new prospects for the development of technical sciences on an industrial scale, but also introduces new technologies into households. In this study, the kinetics of the hydrolytic degradation of samples obtained by the FDM method from commercially available PLA filaments under a thermally accelerated regime were analyzed. The investigation was conducted at the microstructural, supramolecular, and molecular levels by using methods such as micro-computed tomography (micro-CT), wide-angle X-ray diffraction (WAXD), viscosimetry, and mass erosion measurements. The obtained results clearly present the rapid structural changes in 3D-printed materials during degradation due to their amorphous initial structure. The complementary studies carried out at different scale levels allowed us to demonstrate the relationship between the observed structural changes in the samples and the hydrolytic decomposition of the polymer chains, which made it possible to scientifically understand the process and expand the knowledge on biodegradation.

Assessment of Impact of the Surface Modification Techniques on Structural, Biophysical, and Electrically Conductive Properties of Different Fabrics.

This article presents studies on the evaluation of the impact of surface modification of cotton, viscose, and polyester fabrics using three techniques (flocking, layer by layer, and screen printing) with materials with electrically conductive properties on their structural, biophysical, and conductive properties. Each tested fabric is characterized by specific biophysical properties. which can be disturbed by various modification methods, therefore, the following tests were carried out in the article: optical microscopy, micro-computed tomography, guarded perspiration heating plate, air permeability, sorption and electrical conductivity tester. The use of screen printing increased the thermal resistance of the cotton woven fabric by 119%, the polyester woven fabric by 156%, and the viscose fabric by 261%. The smallest changes in thermal resistance compared to unmodified textiles were observed in layer by layer modified fabrics and are as follows: -15% (cotton woven fabric), +77% (PES woven fabric), and +80% (viscose woven fabric).

Micro-CT Evaluation of Microgaps at Implant-Abutment Connection.

The assessment of microgaps at the implant-abutment interface is an important factor that may influence clinical success. Thus, the aim of this study was to evaluate the size of microgaps between prefabricated and customised abutments (Astra Tech, Dentsply, York, PA, USA; Apollo Implants Components, Pabianice, Poland) mounted on a standard implant. The measurement of the microgap was performed using micro-computed tomography (MCT). Due to 15-degree rotation of samples, 24 microsections were obtained. Scans were performed at four levels established at the interface between the abutment and the implant neck. Moreover, the volume of the microgap was evaluated. The size of the microgap at all measured levels varied from 0.1 to 3.7 µm for Astra and from 0.1 to 4.9 µm for Apollo (p > 0.05). Moreover, 90% of the Astra specimens and 70% of the Apollo specimens did not exhibit any microgaps. The highest mean values of microgap size for both groups were detected at the lowest portion of the abutment (p > 0.05). Additionally, the average microgap volume was greater for Apollo than for Astra (p > 0.05). It can be concluded that most samples did not exhibit any microgaps. Furthermore, the linear and volumetric dimensions of microgaps observed at the interface between Apollo or Astra abutments and Astra implants were comparable. Additionally, all tested components presented microgaps (if any) that were clinically acceptable. However, the microgap size of the Apollo abutment was higher and more variable than that of the Astra one.

The Influence of Surface Modification with Biopolymers on the Structure of Melt-Blown and Spun-Bonded Poly(lactic acid) Nonwovens.

The article presents the continuation of the research on modification of fibrous carriers based on poly(lactic acid) using the electrophoretic deposition (EPD) method by the two types of biocompatible polymers-sodium hyaluronate and sodium alginate. Such modified nonwovens, differing in the structural parameters due to different manufacturing methods, could be potentially used in different biomedical applications. The results of the analysis indicate that the EPD process significantly changes the structural characteristics of the carrier in terms of thickness and porosity, which not always can be beneficial in terms of the final application. The varying structure of both carriers significantly influences the mode of deposition of the layer, the efficiency of the deposition process as well as the structural characteristics of the carrier after deposition. Microtomographic and SEM studies were employed to analyze the structure of deposits, and FTIR analysis allowed for confirmation of the occurrence of the polymer layers and its chemical structure.

A Micro-CT Analysis of Initial and Long-Term Pores Volume and Porosity of Bioactive Endodontic Sealers.

The evaluation of the porosities within the interface of root canals obturated with endodontics materials is extremely important for the long-term success of endodontic treatments. The aim of this study was to compare initial and long-term volume of pores (total, open, closed) and porosity (total, regional) of three bioactive endodontic sealers: GuttaFlow Bioseal, Total Fill BC Sealer, and BioRoot RCS. Root canals were obturated with three "bioactive" sealers using the single-cone technique. The volume of open and closed pores and porosity were calculated using a micro-computed tomography (MCT) method. The measurements were performed after 7 days (initial) and after 6 months (long-term) of incubation. Statistical significance was considered at p < 0.05. The total volume of pores remained unchanged after the 6-month storage. GuttaFlow Bioseal exhibited significantly higher long-term volume in open pores than Total Fill BC Sealer. The total porosity in all the tested sealers presented no statistically significant change after the 6-month storage, except for BioRoot RCS. The total porosity values of this latter material significantly increased after long-term incubation, especially in the apical region. In conclusion, the use of bioactive sealers with excessive tendency to create porosities both in shorth- and long-term periods of storage may compromise the long-term success of endodontic treatments.

Modeling of Heat Transfer through Firefighters Multilayer Protective Clothing Using the Computational Fluid Dynamics Assisted by X-ray Microtomography and Thermography.

This paper explores the modeling of physical phenomena that occur in clothing that affect the safety and biophysical comfort of the user. Three-dimensional models of textile assemblies with complex morphology used in firefighters' multilayer protective clothing were designed in a CAD environment. The main goal of the research was to design and experimentally verify (by thermography) the models in terms of simulations when the heat transfer occurs through them in selected ambient conditions using the finite volume method. The designed models took into account the subtle differences in the geometry of selected assemblies determined by high-resolution X-ray microtomography. The designed models made it possible to calculate heat transport with a difference of about 2% to 5% in comparison to experiment that depend on the ambient conditions and the complexity of the model geometry. Moreover, the comparison of the simulation results with the experimental outcomes shows that the mapping of subtle differences in the internal structure of the assemblies in the designed models allows us to observe differences in the modeled heat transfer.

Assessment of the Impact of Ionizing Radiation Absorption on the Structural, Mechanical and Biophysical Properties of Textiles Used in Multilayer Space Suit.

The article presents research on ergonomics, biophysical comfort and safety of protective clothing. The resistance of the structural, thermal and mechanical properties of five fabrics (CBXS400, GG200T, Twaron CT736, Dyneema HB26 and T1790C), differing in geometry and raw material composition used in space suits, to dangerous ionizing radiation (ß and γ) occurring in space was tested. For both types of radiation, four identical one-time doses in the range of 25-100 kGy were used. The effect of the applied absorbed doses of ß and γ radiation on the parameters of textiles influencing ergonomics and safety of the cosmonaut's work was verified by structural tests (micro-computed tomography and optical microcopy), thermal resistance tests (sweating guarded-hotplate) and strength tests (tensile testing machine). Experimental studies of thermal properties are supplemented with heat transport simulations using the finite volume method performed with 3D models of real textiles. The greatest reduction of thermal resistance for Twaron CT736 (-0.0667 m2·°C·W-1 for 100 kGy of ß-radiation) and Dyneema HB26 (-0.0347 m2·°C·W-1 for 50 kGy of ß-radiation) is observed. Strength tests have shown that all tested textiles are resistant to both types of radiation. Three textiles were selected to create a three-layer assembly with potential application in a cosmonaut's glove (Extravehicular Activity-EVA).

Assessment of the Impact of the Surface Modification Processes of Cotton and Polyester Fabrics with Various Techniques on Their Structural, Biophysical, Sensory, and Mechanical Properties.

This article presents research on the assessment of the impact of surface modification of cotton and polyester fabrics using four techniques (flocking, layer by layer, screen printing and thermal-transfer printing) on their structural, mechanical, biophysical, and sensory properties. Depending on geometry and raw materials of the fabrics, the clothing made of them it is characterized by certain biophysical properties which are intended to protect the human body against external factors, but also against excessive sweating and overheating or cooling down. The aforementioned properties of the modified textiles were determined with: optical microscopy, microcomputed tomography, a tensile testing machine, sweating guarded-hotplate, air permeability tester, and the Kawabata evaluation system. Based on analysis of obtained results, it can be concluded that flocking reduces air permeability the most (-77% for cotton fabric and -99.7% for polyester fabric), and total hand value (-58% and -57%) and increases water vapor resistance the most (+769% and +612%) while the screen printing increases the thermal resistance the most (+119% and +156%) compared to unmodified textiles. It can be concluded that, when modifying textile substrates, the area of modification and their size on clothing products should be carefully selected so as not to adversely affect the feelings of potential wearers.

Polymer-Based Electrophoretic Deposition of Nonwovens for Medical Applications: The Effect of Carrier Structure, Solution, and Process Parameters.

Hyaluronate and alginate are non-toxic and biocompatible polymers, which can be used for surface modification and functionalization of many kinds of materials. Electrophoretic deposition (EPD) has several advantages, including its versatility, simplicity, and ability to coat substrates with complex shapes, and is used for the creation of antimicrobial or hydrophobic coatings on metallic biomaterials, among other applications. However, its utilization for applying biopolymer layers on textiles is very limited due to the more complex structure and spatial characteristics of fibrous materials. The aim of this research was to analyze the effects of selected EPD process parameters and the structural characteristics of fibrous carriers on the kinetics of the process and the microscopic characteristics of the deposited layers. The influence of solution characteristics, process parameters, and carrier structures obtained using two different techniques (melt blown and spun-bonded) were analyzed. The morphology and structure of the created deposits were analyzed using scanning electron microscopy and computed tomography, and molecular structure analysis was performed with Fourier Transform Infrared spectroscopy. The surface mass and thickness of fibrous poly (lactic acid)-based carriers were analyzed in accordance with the respective standards. This study serves as a basis for discussion and further development of this method with regard to fibrous materials for medical applications.

Assessment of the Impact of Clothing Structures for Premature Babies on Biophysical Properties.

This article presents research on ergonomics and physiological comfort of protective clothing. Biophysical properties of selected three-layer textile assemblies that differ in geometry and raw material composition for the production of types of mummy sleeping bags for premature babies were investigated. The tests included measurements of air permeability, thermal resistance and water vapor resistance (both by means of human skin model), thermal insulation, and water vapor resistance (both using newborn manikin). Experimental research was supplemented by modeling the thermal insulation of the assemblies by designing their 3D models using selected CAD software and applying the finite volume method. The obtained results allowed the evaluation of the influence of different geometry and the raw material composition of the proposed assemblies on the performance parameters of protective clothing.

Shaping Ability of ProTaper Next, Hyflex CM, and V-Taper 2H Nickel-Titanium Files in Mandibular Molars: A Micro-computed Tomographic Study.

Introduction: Although micro-computed tomography (MCT) evaluation of the shaping ability of ProTaper Next (PTN) and Hyflex CM (HCM) files has been reported, to our knowledge, no study has assessed the performance of V-Taper 2H (VT) files. The aim of this study was to evaluate and compare the shaping ability of PTN, HCM, and VT systems in the mesial canals of mandibular molars using MCT. Methods and Materials: Thirty extracted first and second mandibular molars were scanned using MCT and randomly assigned to HCM, PTN, and VT groups. Images obtained before and after preparation were evaluated for the increase in the root canal volume, untouched surface area, and amount of accumulated hard tissue debris. One-way analysis of variance (ANOVA) and Kruskal-Wallis test were used to compare the variables in the groups (α=5%). Results: There were no statistically significant between-group differences in the postoperative measurements (P>0.05). The canal volume increased in all three groups: PTN (73.84%), VT (73.48%), and HCM (49.29%). The largest and smallest untouched areas were observed in the PTN (41.37%) and VT (30.85%) groups, respectively (P>0.05). The debris formed during canal preparation was 1.84%, 2.16%, and 2.42% in the VT, PTN, and HCM groups, respectively (P>0.05). Conclusions: Based on our in vitro study, the PTN, HCM, and VT systems showed similar shaping abilities. None of the tested canals were completely free from debris, while the untouched surface area was considerably large. The VT system had the most favorable results with the smallest untouched surface area and least debris were. We would recommend further trials to endorse these findings.