Materials

The biomedical Ti–13Zr–13Nb bi-phase (α + β) alloy for long-term applications in implantology has recently been developed. The porous oxide nanotubes’ (ONTs) layers of various geometries and lengths on the Ti–13Zr–13Nb alloy surface can be produced by anodizing to improve osseointegration. This work was aimed at how anodizing conditions determinatine the micromechanical and biotribological properties of the Ti–13Zr–13Nb alloy. First-generation (1G), second-generation (2G), and third-generation (3G) ONT layers were produced on the Ti–13Zr–13Nb alloy surface by anodizing. The microstructure was characterized using SEM. Micromechanical properties were investigated by the Vickers microhardness test under variable loads. Biotribological properties were examined in Ringer’s solution in a reciprocating motion in the ball-on-flat system. The 2D roughness profiles method was used to assess the wear tracks of the tested materials. Wear scars’ analysis of the ZrO₂ ball was performed using optical microscopy. It was found that the composition of the electrolyte with the presence of fluoride ions was an essential factor influencing the micromechanical and biotribological properties of the obtained ONT layers. The three-body abrasion wear mechanism was proposed to explain the biotribological wear in Ringer’s solution for the Ti–13Zr–13Nb alloy before and after anodizing. Full article

The use of dental ceramics as restorative materials requires corresponding luting materials (cements) that, in turn, influence the visual appearance of the restoration. Due to the high light transmission through the ceramics, the cements can affect the color perception of the dental restoration. This study aims to investigate the optical effects of various cements on the visual appearance of full-ceramic restorations. Three fixing polymer resins (Bifix SE (VOCO GmbH, Cuxhafen, Germany), Breeze^TM (Pentron Clinical, West Collins Orange, CA, USA), and Panavia^TM F. 2.0 (Kuraray, Noritake, Osaka, Japan)), with layer thicknesses of 50, 100, 200, and 250 µm, were applied onto a ceramic base model (0.4 mm thick), and irradiated with laser light of wavelengths 532, 632.8, and 1064 nm. Light intensities and scattering effects of light of various wavelengths were angle-dependent, analyzed using a goniophotometer with perpendicular light incidence on the sample specimen (base model plus luting material). In addition, the transmitted power of the light through the sample specimen was determined as a function of the layer thickness. With increasing layer thickness, power losses of respectively 30% for Bifix SE and Breeze^TM in the visible spectral range were comparable, whereas Panavia^TM F. 2.0 showed a power loss of ca. 44% here. For the near-infrared range, the power losses for all cements were 25%. This could be confirmed by the interpretation of the line widths. Moreover, the line widths for thin cement layer thicknesses (50 and 100 µm) in the visible spectral range displayed only a redistribution of light by scattering, which does not affect color perception at all. In addition, at 200 and 250 µm, absorption occurred which causes a change in color perception. Within the scope of this study, it could be shown that for thin-layer thicknesses of the cement applied here, there is no adverse optical effect on the aesthetic visual appearance of the restoration. Full article

The study presents an experimental evaluation to improve the resistivity of binders with “Styrene-Butadiene-Styrene” (SBS) and “Processed oil” by studying the physical properties, rheology, and cracking. For this experiment, PG 64-22 was mixed with SBS at different percentages of 5%, 10%, and 15% by weight of the original binder with two processed oil contents of 6% and 12% by weight of the binder. Laboratory tests have been conducted at various high, medium, and low temperature ranges to evaluate their properties. The processed oil polymer modified asphalt (PMA) binder is artificially aged in both the short and long-term using a Rolling Thin Film Oven (RTFO) and a Pressure Aging Vessel (PAV). The Superpave testing method was performed on modified binders using a Rotational Viscometer (RV), Dynamic Shear Rheometer (DSR), and Bending Beam Rheometer (BBR). The results of this study illustrate (1) The addition of SBS leads to higher viscosity, but the co-modification of asphalt binder with the processed oil shows a significant modulation of the viscosity value. (2) In addition, processed oil reduced the resistance to rutting, but the addition of SBS significantly improved the rutting resistance of the asphalt binder. (3) The addition of SBS and processed oil improved the value of G sin δ, notably. (4) According to BBR, it has been shown that the addition of SBS in addition to the processed oil improves the stiffness values of modified asphalt binders. Full article

Recycling coal gangue as aggregate to produce concrete in situ is the most effective way to solve the problem of deposited coal gangue in mines. Nevertheless, the mine environment underground is rich in sulfate ions, posing a threat to the durability of coal gangue concrete (CGC). Hence, the degradation process of sulfate-attacked CGC is investigated. A series of tests is performed to evaluate its variation law of mass, dynamic elastic modulus, compressive strength and sulfate ion distribution. Meanwhile, the microstructure and phases of sulfate-attacked CGC are identified by scanning electron microscopy, X-ray diffraction and thermogravimetric analysis. The results indicate that the residual compressive strength ratio of CGC is higher than that of normal concrete after a 240 d sulfate attack, implying a superior sulfate resistance for CGC. Additionally, the higher the sulfate concentration, the more severe the degradation. Except for the secondary hydration of CGC itself, the diffused sulfate ions also react with Ca(OH)₂, forming gypsum and ettringite; this plays a positive role in filling the pores at the early stage, whereas, at the later stage, the generated micro-cracks are detrimental to the performance of CGC. In particular, the proposed sulfate corrosion model elucidates the degradation mechanism of CGC exposed to a sulfate-rich environment. Full article

As a composite material, the stability of rock mass is usually controlled by a joint. During the process of excavation, the normal stress of the joint decreases continuously, and then the shear strength of the joint decreases, which may eventually lead to the instability and failure of rock mass. Previous studies have mainly focused on the shear behavior of joints under constant normal stress, but have rarely considered the unloading of normal stress. In this paper, a direct shear test of joints with different roughness was carried out, in which the shear stress remained unchanged while the normal stress decreased. The strength characteristics of joints were explored, and the deformation and acoustic emission-counting characteristics of joints were analyzed by digital image correlation (DIC) techniques and acoustic emission (AE). A new method for predicting the instability of joints under normal unloading was proposed based on the evolution law of normal deformation energy (U_n), tangential deformation energy (U_s) and total deformation energy (U₀). The results show the following: (1) The unloading amount of normal stress was enlarged for greater initial normal stress and roughness, while it decreased with an increase in initial shear stress. (2) AE events reached their maximum when the normal stress was equal to the failure normal stress, and the b-value fluctuated more frequently in stable development periods under normal unloading conditions. (3) U₀ would change with the loading and unloading of stress, and this may be used to predict the unloading instability of rock mass using the abrupt change of U₀. Full article

Solid-state supercapacitors (SSCs) consist of porous carbon electrodes and gel-polymer electrolytes and are used in novel energy storage applications. The current study aims to simulate the impedance of SSCs using a clearly defined equivalent circuit (EC) model with the ultimate goal of improving their performance. To this end, a conventional mathematical and a physicochemical model were adapted. The impedance was measured by electrochemical impedance spectroscopy (EIS). An EC consisting of electrical elements was introduced for each modeling approach. The mathematical model was purely based on a best-fit method and utilized an EC with intuitive elements. In contrast, the physicochemical model was motivated by advanced theories and allowed meaningful associations with properties at the electrode, the electrolyte, and their interface. The physicochemical model showed a higher approximation ability (relative error of 3.7%) due to the interface impedance integration in a more complex circuit design. However, this model required more modeling and optimization effort. Moreover, the fitted parameters differed from the analytically calculated ones due to uncertainties in the SSC’s microscale configuration, which need further investigations. Nevertheless, the results show that the proposed physicochemical model is promising in simulating EIS data of SSCs with the additional advantage of utilizing well-reasoned property-based EC elements. Full article

Novel near-infrared (NIR) phosphors are in demand for light-emitting diode (LED) devices to extend their suitability for new applications and, in turn, support the sustainable and healthy development of the LED industry. The Cr³⁺ has been used as an activator in the development of new NIR phosphors. However, one main obstacle for the Cr³⁺-activated phosphors is the low luminescence efficiency due to the spin-forbidden d-d transition of Cr³⁺. The rare-earth (RE) huntite minerals that crystallize in the form of REM₃(BO₃)₄ (M = Al, Sc, Cr, Fe, Ga) have a large family of members, including the rare-earth scandium borates of RESc₃(BO₃)₄. Interestingly, in our research, we found that the luminescence efficiency of Cr³⁺ in the CeSc₃(BO₃)₄ host, whose quantum yield was measured at 56%, is several times higher than that in GdSc₃(BO₃)₄, TbSc₃(BO₃)₄, and LuSc₃(BO₃)₄ hosts. Hereby, the energy conversion and transfer in the luminescence of CeSc₃(BO₃)₄:Cr³⁺ phosphor were examined. The Stokes shift of electron energy conversion within the Cr^{3+ 4}T_2g level for the emission at 818 nm and excitation at 625 nm in CeSc₃(BO₃)₄ host was evaluated to be 3775.1 cm⁻¹, and the super-large splitting energy of the ²F_5/2 and ²F₇₂ sub-states of the Ce³⁺ 4f¹ state, about 3000 cm⁻¹, was found in CeSc₃(BO₃)₄ host. The typical electronic thermal vibration peaks were observed in the excitation spectra of CeSc₃(BO₃)₄:Cr³⁺. On this basis, the smallest phonon energy, around 347.7 cm⁻¹, of the CeSc₃(BO₃)₄ host was estimated. Finally, the energy transfer that is responsible for the far higher photoluminescence of Cr³⁺ in CeSc₃(BO₃)₄ than in other hosts was proven through the way of Ce³⁺ emission and Cr³⁺ reabsorption. Full article

This paper presents the results of a study examining the protection time of half-masks containing different types and quantities of carbon sorbents. The protection time afforded by the half-masks was determined by analyzing the adsorption of three substances harmful to human health at their maximum allowable concentrations. Two of the tested half-masks showed comprehensive protection against pollutants contained in smog. Among the tested half-masks, the one with the best protective properties was identified. The longest protection time (over 8 h) was recorded for toluene, followed by over 7 h for sulfur dioxide, and only 2 h for cyclohexane. The morphological structure of nonwovens incorporating the carbon sorbents was examined under a microscope. The study showed that protection time depends on the size of activated carbon particles incorporated in the nonwoven structure as well as on their distribution. Based on these results, we identified the most effective morphological structure of the sorbent in the nonwovens. Full article

TiO₂ nanosheets have been studied as photocatalysts in various fields, and their performance has been actively improved. Herein, we prepared titania nanosheets with a smaller size than those reported previously with a side length of 29 nm and investigated their photocatalytic activity. (NH₄)₂TiF₆ and Ti(OBu)₄ were used as raw materials, and the F/Ti ratio was varied in the range of 0.3 to 2.0 to produce a series of samples with different side lengths by hydrothermal synthesis. A reduction in the F/Ti ratio led to the reduced size of the titanium nanosheets. The photocatalytic activity of each sample was evaluated through the degradation of methylene blue (MB) under ultraviolet (UV) irradiation (365 nm, 2.5 mW/cm²). UV irradiation promoted the decomposition of MB, and the highest degradation efficiency was achieved using titania nanosheets prepared with a F/Ti ratio of 0.3. The high catalytic activity can be attributed to the increase in the surface area due to size reduction. The ratio of the {001} surface exposed on the titania nanosheet also affected the photocatalytic activity; it resulted in increased activation of the reaction. This study demonstrates that further activation of the photocatalytic activity can be achieved by adjusting the size of titania nanosheets. Full article

The article presents research results related to assessing the possibilities of applying modern filtration methods to diagnosing measurement signals. The Fourier transformation does not always provide full information about the signal. It is, therefore, appropriate to complement the methodology with a modern multiscale method: the wavelet transformation. A hybrid combination of two algorithms results in revealing additional signal components, which are invisible in the spectrum in the case of using only the harmonic analysis. The tests performed using both simulated signals and the measured roundness profiles of rollers in rolling bearings proved the advantages of using a complex approach. A combination of the Fourier and wavelet transformations resulted in the possibility to identify the components of the signal, which directly translates into better diagnostics. The tests fill a research gap in terms of complex diagnostics and assessment of profiles, which is very important from the standpoint of the precision industry. Full article

Polarization doping in a GaN-InN system with a graded composition layer was studied using ab initio simulations. The electric charge volume density in the graded concentration part was determined by spatial potential dependence. The emerging graded polarization charge was determined to show that it could be obtained from a polarization difference and the concentration slope. It was shown that the GaN-InN polarization difference is changed by piezoelectric effects. The polarization difference is in agreement with the earlier obtained data despite the relatively narrow bandgap for the simulated system. The hole generation may be applied in the design of blue and green laser and light-emitting diodes. Full article

In this paper, an aluminum foam sandwich (AFS) was prepared by the rolling composite-powder metallurgy method, and its fatigue properties were studied. It was compared with an AFS made by the adhesive method to study its fatigue properties more directly. In this experiment, the fatigue performance was investigated by studying the microscopic interface, fatigue life, deflection curve, and failure mode. The results show that the fatigue life of an AFS with the rolling composite-powder metallurgy method is much longer than that with the adhesive method. The failure mode of an AFS made by the rolling composite-powder metallurgy method is shear failure, and that of an AFS made by the adhesive method is shear failure and interface debonding. An AFS with the rolling composite-powder metallurgy method has better fatigue properties. This paper also explored the fatigue damage model using the fatigue modulus method, and the polynomial fitting method has a higher fitting degree. Full article

The paper presents new reactive materials, namely marl and travertine, and their thermal modifications and the Polonite^® material, analyzing their phosphorus removal from water and wastewater by sorption. Based on the experimental data, an analysis of the factors influencing the sorption capacity of the materials, such as the material dose, pH of the initial solution, process temperature, surface structure, and morphology, was performed. Adsorption isotherms and maximum sorption capacities were determined with the use of the Langmuir, Freundlich, Langmuir–Freundlich, Tóth, Radke–Praunitz, and Marczewski–Jaroniec models. The kinetics of the phosphorus sorption process of the tested materials were described using reversible and irreversible pseudo-first order, pseudo-second order, and mixed models. The natural materials were the most sensitive to changes in the process conditions, such as temperature and pH. The thermal treatment process stabilizes the marl and travertine towards materials with a more homogeneous surface in terms of energy and structure. The fitted models of the adsorption isotherms and kinetic models allowed for an indication of a possible phosphorus-binding mechanism, as well as the maximum amount of this element that can be retained on the materials’ surface under given conditions—raw marl (43.89 mg P/g), raw travertine (140.48 mg P/g), heated marl (80.44 mg P/g), heated travertine (282.34 mg P/g), and Polonite^® (54.33 mg P/g). Full article

The ability of materials to withstand environmental influences is a frequent necessity in many industries. Special requirements are imposed by such industries where surfaces are affected by acidity during the processing or storage of products. In such cases, when the basic surface is exposed to chemical influences, it is possible to use enamel coatings, which, with their properties, guarantee the protection of the surface and achieve the required service life of the material. This article deals mainly with the interaction between the base material and the enamel and its resistance to wear between the original and the renovated surface caused by local heating. The article presents a methodical procedure for the preparation of test specimens with an enamel layer prepared by AWJ cutting, eliminating its damage. There are minimal differences in the microstructure between the original and the renovated surface due to the production technique. The renovated enamel surface had more bubbles of a larger size than the original surface. Good adhesion between the base metal material (substrate) and the ground coat was demonstrated. The tested surfaces demonstrated high resistance to intensive abrasion conditions with low linear wear increments. Full article

In this work, a new design of transparent conductive electrode based on a graphene monolayer is evaluated. This hybrid electrode is incorporated into non-standard, high-efficiency crystalline silicon solar cells, where the conventional emitter is replaced by a MoO_x selective contact. The device characterization reveals a clear electrical improvement when the graphene monolayer is placed as part of the electrode. The current–voltage characteristic of the solar cell with graphene shows an improved FF and V_oc provided by the front electrode modification. Improved conductance values up to 5.5 mS are achieved for the graphene-based electrode, in comparison with 3 mS for bare ITO. In addition, the device efficiency improves by around 1.6% when graphene is incorporated on top. These results so far open the possibility of noticeably improving the contact technology of non-conventional photovoltaic technologies and further enhancing their performance. Full article

AlSi10Mg has a good forming ability and has been widely accepted as an optimal material for selective laser melting (SLM). However, the strength and elongation of unmodified AlSi10Mg are insufficient, which limits its application in the space industry. In this paper, yttrium oxide (Y₂O₃) nanoparticles modified AlSi10Mg composites that were manufactured using SLM. The effects of Y₂O₃ nanoparticles (0~2 wt.% addition) on the microstructure and mechanical properties of AlSi10Mg alloys were investigated. An ultimate tensile strength of 500.3 MPa, a yield strength of 322.3 MPa, an elongation of 9.7%, a good friction coefficient of 0.43, and a wear rate of (3.40 ± 0.09) ×10⁻⁴ mm³·N⁻¹·m⁻¹ were obtained with the addition of 0.5 wt.% Y₂O₃ nanoparticles, and all these parameters were higher than those of the SLMed AlSi10Mg alloy. The microhardness of the composite with 1.0 wt.% Y₂O₃ reached 145.6 HV_0.1, which is an increase of approximately 22% compared to the unreinforced AlSi10Mg. The improvement of tensile properties can mainly be attributed to Orowan strengthening, fine grain strengthening, and load-bearing strengthening. The results show that adding an appropriate amount of Y₂O₃ nanoparticles can significantly improve the properties of the SLMed AlSi10Mg alloy. Full article

The objective of this study was to compare marginal bone loss, surgical and clinical complications, and dental implant survival rate in bilateral maxillary sinus augmented by autologous or porcine xenograft. A randomized controlled clinical trial using split-mouth design enrolled 12 consent adult patients (59.7 ± 8.7 years), who received bilateral maxillary sinus floor augmentation for oral rehabilitation with implant-supported prosthesis. Each patient received both the autologous bone from the mandible (control) or porcine xenograft (test) during the random bilateral sinus lift surgery. A total of 39 dental implants were placed in the posterior maxilla of the 12 patients after 6 months, being rehabilitated after the respective osseointegration period. Both graft materials demonstrated a high implant survival rate at 12 months: 95% for the xenograft side, only 1 implant without osseointegration, and 100% for the autologous side. Radiographic bone loss was low and similar for both groups: control group with a mean of 0.063 ± 0.126, and test group with a mean of 0.092 ± 0.163. No major surgical-related complications have occurred. Only one patient had several prosthetic complications due to fractures of prosthetic components. The maxillary sinus augmentation procedure, both with autologous bone and porcine xenograft materials, is an excellent clinical option procedure for the prosthetic rehabilitation of atrophic maxillae, with low marginal bone loss after one year follow-up, few clinical complications, and a high implant survival rate. Full article

Classified information is information of vital importance to the State, which must be protected against disclosure, misuse, damage, unauthorized reproduction, destruction, loss or theft in the interest of the State. At present, there are four levels of classification. For each classification level, precise requirements are laid down for the material of the walls, partitions and ceilings of the rooms in which classified information is stored. Several types of materials are defined for each classification level. The objective of this study was to test and determine whether the different types of materials proposed for the Confidential level meet the same level of resistance. A drop weight test via pendulum was used to determine the resistance. A 50 kg weight was used to break through a 60 × 100 cm sample. The impact of the weight was on the exact center of the sample. The result of the tests was that to break through samples of different materials, large differences in the drop height of the weight were required. The most resistant was the specimen made of reinforced concrete, which required 3 impacts from a height of 80 cm to break through. On the contrary, the least resistant were the specimens made of masonry of autoclaved aerated concrete, where after 2 falls from a height of 5 cm, the sample broke into 2 parts. Full article

Riboflavin (RF), which is also known as vitamin B2, is a water-soluble vitamin. RF is a nontoxic and biocompatible natural substance. It absorbs light (at wavelengths of 380 and 450 nm) in the presence of oxygen to form reactive singlet oxygen (¹O₂). The generated singlet oxygen acts as a photoinitiator to induce the oxidation of biomolecules, such as amino acids, proteins, and nucleotides, or to initiate chemical reactions, such as the thiol-ene reaction and crosslinking of tyramine and furfuryl groups. In this review, we focus on the chemical mechanism and utilization of the photochemistry of RF, such as protein crosslinking and hydrogel formation. Currently, the crosslinking method using RF as a photoinitiator is actively employed in ophthalmic clinics. However, a significant broadening is expected in its range of applications, such as in tissue engineering and drug delivery. Full article