Resistance Values Research Articles

Comparative Evaluation of Fracture Strength of Implant Supported Crown Fabricated from CAD/CAM and 3D Printed Resin Matrix Ceramic

Objective: To compare fracture strength of screw-retained implant-supported crown of resin matrix ceramic when fabricated using CAD/CAM and 3D printing Material and method: vericom Mazic® Duro (CAD/CAM Nano Hybrid Ceramic) was used as particle-filled composite CAD/CAM material, saremco Print Crowntec (3D printable resins-based) as 3D printed composite material, and the control group was composed of IPS e.max. ZirCAD ivoclar vivadent (zirconia) was used to fabricate mandibular first molar screw-retained, implant-supported crowns. After the fabrication, the crowns were cemented with the Rely X U200 self-adhesive resin cement (3M ESPE, Germany) on stock abutments tightened to analogs embedded in acrylic resin. Finally, all crowns were subjected to a fracture resistance test. fracture strength was evaluated by using one–way ANOVA with Chi-square used for the association between the modes of fracture. Result: The results showed that there were significant differences between all the groups used, the control group (Group zirconia) was significantly higher, as the mean was equal to 6391 N. Followed by Group vericom (cad/cam) with a mean of 2558 N, then Group seramco (3D printing) with a mean of 817.92 N. Dunnett T3 test showed statistically significant differences in fracture resistance between the three groups. There was no significant difference between the modes of fracture and the methods. Conclusion: Screw-retained implant-supported crowns manufactured by CAD/CAM technique had better fracture resistance value than those of the 3D printed technique. Clinical Relevance: resin matrix ceramic is a possible substitute for zirconia in an implant-supported crown

Pemanfaatan Limbah Ban Bekas untuk Sintesis Nanokomposit MnO2/C dengan Metode Hidrotermal sebagai Material Superkapasitor

Activated carbon from waste tires is used as MnO2 metal oxide doping in making MnO2/C-based nanocomposites into high-density and environmentally friendly supercapacitor electrodes. The MnO2/C nanocomposite synthesis process was carried out using the hydrothermal method by varying the mass of activated carbon by 1.25 g, 2.5 g and 3.75 g to determine the optimum results. Based on the results of research that has been carried out, it shows that MnO2/C can be used as a high density supercapacitor electrode. This is in accordance with the XRD test results which show that the MnO2 nanocomposite with the addition of C was successfully synthesized and has an orthorhombic crystalline phase. The SEM test results show that the material has almost the same morphology, namely many protrusions which make each particle have high roughness. The most optimal results were obtained from the MnO2/C-50 variation because it has the highest C element content, namely 39.93%, so it has the highest capacitance value of 5.791 f/g during the CV test. The GCD test shows that electrodes with a carbon variation of 2.5 g have a much longer and constant charge-discharge measurement time. In the EIS test, this variation shows a resistance value that is not too high and not too small, materials that have good storage capacity or capacity have moderate resistance.

Research on hydrodynamics of the thermal agent flow for the beet pulp filtration drying

The reuse and recycling of secondary raw materials is essential to ensure sustainable development and the rational use of natural resources. One of the most important types of secondary raw materials is plant-based food waste, which is generated in large quantities at food processing plants, including sugar beet pulp, which is a valuable resource for further use. One of the main problems with using beet pulp is its high moisture content, which is ≈ 80 % wt. It is proposed to dry beet pulp by filtration drying, which is highly efficient. The calculation of industrial equipment for filtration drying should take into account the costs of overcoming the hydraulic resistance of a stationary layer of material. The aim of the article was to study the hydrodynamics of the flow of a thermal agent through a stationary layer of beet pulp of different heights and to perform computer modelling of this process. The obtained results will allow predicting the hydraulic resistance of a material layer of different heights and the required pressure drop to ensure the course of the drying process under various possible technological modes. For computer modelling of the flow of a thermal agent through a stationary layer of beet pulp, the porous media method was used in the ANSYS Fluent 2022 R2 software package. The process was simulated on the basis of the Navier-Stokes system of differential equations and the flow continuity equation with the additional use of the Darcy equation to determine the value of the hydraulic resistance of the layer ΔP. Computer simulations of the hydrodynamics of the thermal agent flow through a stationary layer of beet pulp were performed for the range of stationary layer heights H = 90÷110 mm with an interval of 5 mm. The obtained data showed a relative average deviation of 2.19 % from the experimental data, which indicates a high accuracy of calculations in this range. The study for the extended range of layer heights H = 80÷120 mm with an interval of 10 mm showed an increase in the relative average deviation to 4.09 % from the experimental data, but the results are still sufficiently accurate for practical use in the calculation of drying equipment. The obtained dependencies may be used to determine the value of the hydraulic resistance of a stationary layer of material using the filtration drying method and for practical calculations of drying equipment. Together with the results of the kinetic regularities of filtration drying, the obtained experimental data and computer modelling data on the hydrodynamics of the flow of a heat transfer agent through a material layer will allow us to calculate the optimal parameters of filtration drying for beet pulp and to assess the efficiency of filtration drying for drying beet pulp in comparison with other methods of dehydration.

T-matrix of piezoelectric shunt inclusions on a thin plate

Developing piezoelectric-based plate-like metamaterials necessitates an effective modeling method to elucidate the omnidirectional wave properties of piezoelectric coupled inclusions on a thin plate. The commonly used methods, such as the transfer-matrix method and finite element method, are inadequate for analyzing the transmission and reflection of omnidirectional waves in a two-dimensional elastic medium. Unlike the existing methods, the multiple scattering method employs Bessel functions as the displacement-basis methods which can accurately describe the propagation and scattering characteristics of omnidirectional waves. This paper develops a novel T-matrix formulation to support the multiple scattering method, representing the input-output relationship between incident and reflected waves from a piezoelectric shunt inclusion on a host thin plate. The piezoelectric shunt inclusion comprises a varying-thickness substrate bonded with piezoelectric shunting patches. The T-matrix of the piezoelectric shunt inclusion is formulated by integrating the wave-based method with Rayleigh-Ritz method. The derived T-matrix is then used to semi-analytically analyze the far-field scattering and reflection properties of a single inclusion. Numerical results capture the scattering properties resulting from trapped mode resonances of the piezoelectric shunt inclusion. Additionally, the capability of the piezoelectric shunt damping to design and tune multiple critical coupling conditions for axisymmetric modes of thin plates is parametrically investigated by varying the values of inductors and resistors.

Analysis of Signal Transmission Efficiency in Semiconductor Interconnect and Proposal of Enhanced Structures

As the demand for high-density, high-performance technologies in semiconductor systems increases, efforts are being made to mitigate and optimize the issues of high current density and heat generation within interconnects to ensure reliability. While interconnects are the most fundamental pathways for transmitting current signals, there has been relatively little research conducted on them compared to individual unit devices from the perspective of overall system performance. However, as integration density increases, the amount of loss in interconnects also rises, necessitating research and development to minimize these losses. In this study, we propose a method to analyze power efficiency by utilizing the differences between simulation results and measured results of interconnect structures. We confirmed that the difference between theoretical resistance values and actual measured values varies with the contact area ratio between metal lines and vias, and we analyzed the power efficiency based on these differences. Using the findings, we proposed and validated a structure that can improve power efficiency. This study presents a method to analyze power efficiency and suggests ways to achieve higher power efficiency within the limited specifications of interconnects. This contributes to enhancing power efficiency and ensuring reliability, thereby preserving the performance of the overall system in highly integrated semiconductor systems.

Simultaneous determination and association between serum levels of irisin and chemerin in PCOS.

To determine the serum levels of irisin, chemerin and insulin in women with polycystic ovary syndrome, and to compare their levels with respect to bodyweight and body mass index. The case-control study was conducted at the Department of Clinical Chemistry, College of Medicine, Mustansiriyah University, Baghdad, Iraq, from December 2020 to February 2022, and comprised healthy controls in group I who were matched for bodyweight and body mass index with polycystic ovary syndrome women in group II. Subjects and cases were inducted using purposive sampling technique Subgroups were also formed on the basis of normal body mass index, and overweight-obese status. Serum irisin, chemerin, insulin and free testosterone levels, anthropometric measurements, lipid profile as well as hormonal and biochemical parameters were noted. Data was analysed using SPSS 25. Of the 88 subjects, 32(36.4%) were in group I with mean age 25.1±4.7 years, and 56(63.6%) in group II with mean age 25.0±6.3 years (p>0.05). Both the groups were divided into two equal subgroups A and B. Group II had significantly higher mean body mass index (p=0.007) and adult body fat (p=0.018). Group II women had significantly high fasting serum insulin levels (p<0.001) and homeostatic model assessment for insulin resistance values (p<0.001). Serum irisin had significant positive correlation with serum chemerin (p=0.014) in group II. Serum free testosterone, irisin and chemerin were significantly higher (p<0.001) in group II compared to group I except for chemerin which showed no significant differences among women with normal body mass index (p=0.071). Serum levels of irisin and chemerin could serve as biomarkers of polycystic ovary syndrome.

Effects of fly ash, activator ratio and steel fiber on freeze–thaw cycle, sulfuric acid, thermal conductivity and impact resistance of silica fume based AAHSMs

This study is focused on the effects of Class C fly ash (FA), NaOH/Na2SiO3 (SH/SS) ratio and steel fiber (STF) on the freeze–thaw (F-T) cycle, sulfuric acid, thermal conductivity and impact resistance of silica fume (SF) based alkali activated high strength mortars (AAHSMs). In the AAHSM mixtures, FA in different proportions (10 %, 15 %, 20 % and 25 %) is used instead of SF by weight. All the mixtures are prepared with water-to-binder rate of 0.32. F-T cycle results exhibit that the flexural strength (ffs) and compressive strength (fc) values of SF based AAHSMs without and with STF are less affected than those of ordinary Portland cement (OPC) based high strength mortars (OPCHSMs) without and with STF. After 300 F-T cycles, the ffs and fc values of SF based AAHSMs without and with STF are still over 14 MPa and 95 MPa, respectively. After exposure to 20 % sulfuric acid solution for 90 and 180 days, the SF based AAHSMs without and with STF exhibit super performance (i.e., fc values between 78.95 MPa and 96.81 MPa), while the surfaces of OPCHSMs without and with STF are disintegrated. Additionally, the effects of F-T cycle and sulfuric acid solution on SF based AAHSM and OPCHSM are examined with the microstructure analyses. Thermal conductivity results show that the SF based AAHSMs without and with STF perform better than the OPCHSMs without and with STF. The thermal conductivity results of OPCHSMs without and with STF vary between 0.630 W/m.K and 0.697 W/m.K, while the thermal conductivity results of SF based AAHSMs without and with STF range from 0.507 W/m.K and 0.623 W/m.K. Thermal conductivity results are adversely influenced by increasing STF content in the SF based AAHSMs and OPCHSMs. Impact resistance results show that the SF based AAHSMs without and with STF perform better than the OPCHSMs without and with STF. Moreover, the impact resistance values increase, as the amount of STF used in the SF based AAHSMs and OPCHSMs increases.

Elucidating the increased ohmic resistances in zero-gap alkaline water electrolysis

This study investigates the increased ohmic resistances observed in zero-gap alkaline water electrolyzers, aiming to provide insights that can help enhance electrolyzer efficiency and enable operation at higher current densities. Electrochemical impedance spectroscopy (EIS) has been employed in combination with chronopotentiometry, utilizing a custom-designed flow cell with nickel perforated electrodes and a Zirfon UTP 500 diaphragm. Observed differences in area-ohmic resistance values obtained through I-V fitting and EIS, are ascribed to a non-linear Tafel slope at higher current densities. Ohmic resistance values measured with EIS are up to 27% higher than the ex-situ determined value, a significantly smaller percentage than expected based on previous studies. The presence of bubbles outside and inside the diaphragm is identified as the key factor contributing to this increased resistance. We recommend the use of an improved fitting approach, accounting for non-linear Tafel behavior, and the use of a 4-terminal configuration when performing EIS measurements to minimize cable and contact resistance.

Effect of different preparation designs and material types on fracture resistance of minimally invasive posterior indirect adhesive restorations.

To evaluate the impact of various preparation designs and the material type on fracture resistance of minimally invasive posterior indirect adhesive restorations after aging using a digital standardization method. One-hundred sixty human maxillary premolars free from caries were assigned into 16groups (n=10): bevel design on enamel substrate with mesial box only (VEM), butt joint design on enamel substrate with mesial box only (BEM), bevel design on enamel substrate with mesial and distal box (VED), butt joint design on enamel substrate with mesial and distal box (BED), bevel design on dentin substrate with mesial box only (VDM), butt joint design on dentin substrate with mesial box only (BDM), bevel design on dentin substrate with mesial and distal box (VDD), and butt joint design on dentin substrate with mesial and distal box (BDD). Each group was restored with pressable lithium disilicate (LS2) or disperse-filled polymer composite (DPC) materials. Adhesive resin cement was used to bond the restorations. The specimens were aged for 10,000 thermal cycles (5°C and 55°C), then 240,000 chewing cycles. Each specimen was subjected to compressive axial load until failure. A two-way analysis of variance (ANOVA) test followed by a post hoc Tukey test was used to analyze the data (α=0.05). The two-way ANOVA test revealed a significant difference among designs (p<0.001) and materials (p<0.001) with no interaction effect (p=0.07) between the variables. The Post hoc Tukey test revealed that the VEM group exhibited the highest mean fracture resistance value, while the BDM group had the lowest. The LS2 groups showed the highest mean fracture resistance values. The DPC groups showed a restorable fracture pattern compared to the LS2 groups. Bevel and butt joint designs with mesial or distal boxes are recommended for conservative posterior indirect adhesive restorations in premolar areas. Enamel substrate improved load distribution and fracture resistance. DPCs have restorable failure patterns, while pressed LS2 may harm underlying structures.

Oxygen Vacancy Compensation-Induced Analog Resistive Switching in the SrFeO3-δ/Nb:SrTiO3 Epitaxial Heterojunction for Noise-Tolerant High-Precision Image Recognition.

Neuromorphic computing, inspired by the brain's architecture, promises to surpass the limitations of von Neumann computing. In this paradigm, synaptic devices play a crucial role, with resistive switching memory (memristors) emerging as promising candidates due to their low power consumption and scalability advantages. This study focuses on the development of metal/oxide-semiconductor heterojunctions, which offer several technological advantages and have broad potential for applications in artificial neural synapses. However, constructing high-quality epitaxial interfaces between metal and oxide semiconductors and designing modifiable contact barriers are challenging. Herein, we construct high-quality epitaxial metal/semiconductor interfaces based on the metallicity of the perovskite phase SrFeO3-δ (PV-SFO) and a small Schottky barrier in contact with Nb-doped SrTiO3 (NSTO). X-ray diffraction patterns, reciprocal space mapping results, and cross-sectional transmission electron microscopy images reveal that the prepared PV-SFO film exhibits a perfect single-crystal structure and an excellent epitaxial interface with the NSTO (111) substrate. The corresponding memristor exhibits analog-type resistive-variable characteristics with an ON/OFF ratio of ∼1000, stable data retention after 10,000 s, and no noticeable fluctuation in resistance after 10,000 pulse cycles. Electron energy loss spectroscopy, first-principles calculations, and electrical measurements reveal that compensating or restoring oxygen vacancies at the NSTO surface decreases or increases the contact barrier between PV-SFO and NSTO, respectively, thereby gradually regulating the resistance value. Furthermore, high-quality epitaxial PV-SFO/NSTO devices achieve up to 98.21% recognition accuracy for handwriting recognition tasks using LeNet-5-based network structures and 92.21% accuracy for color images using visual geometry group (VGG) network structures. This work contributes to the advancement of interface-type memristors and provides valuable insights into enhancing synaptic functionality in neuromorphic computing systems.

Recombinant filaggrin-2 improves skin barrier function and attenuates ultraviolet B (UVB) irradiation-induced epidermal barrier disruption

The integrity of the skin barrier is essential for maintaining skin health, with the stratum corneum and filaggrin 2 (FLG-2) playing a key role. FLG-2 deficiency or mutation has been linked to diseases such as atopic dermatitis, while external stressors such as ultraviolet B (UVB) radiation further damage the epidermal barrier. This study investigated the effects of recombinant filaggrin (rFLG) on skin barrier function and UVB induced epidermal destruction. Cell experiments showed that 10 μg/mL of rFLG could increase the mobility of HaCaT cells from 20 % to 42 %, increase the epithelial resistance (TEER) value by about 2 times, and up-regulate the tight junction associated protein by about 2 times. In mouse models of UVB-induced epidermal barrier destruction, rFLG at concentrations of 0.5, 1, and 2 mg/mL showed effective cell uptake and skin penetration, alleviating erythema, and reducing skin thickness in mice by 1.5–3 times. Among them, 2 mg/mL of rFLG treatment restored the expression of tight junction proteins (LOR, ZO-1, and caspase-14), reduced collagen degradation, and reduced oxidative stress by normalizing serum hydroxyproline and superoxide dismutase levels. In addition, 2 mg/mL of rFLG inhibited UVB-induced upregulation of matrix metalloproteinases (MMP-3 and MMP-9) and reduced pro-inflammatory factors (IL-10, IL-1α, IL-6, and TNF-α) and apoptotic markers (P38, Bax, and Bcl-2) to normal levels. These findings suggested that rFLG effectively enhanced skin barrier integrity and mitigated UVB-induced epidermal barrier destruction, highlighting its potential as a therapeutic agent for diseases associated with skin barrier dysfunction.

Delineation of subsurface features by electrical resistivity tomography and induced polarization in upstream basin of Chaq-Chaq dam – northeastern Iraq

The construction of dam is important for many reasons. Prior to construction, it is essential to assess the dam's base reservoir to identify any subsurface cavities. This study was conducted along nine electrical resistivity (ERT) profiles and eight induced polarization (IP) profiles, which are traditional ERT profiles, trending SW to NE direction in the reservoir part of the failed Chaq-Chaq dam NW of Sulaimaniyah city. The aim of this study was to delineate subsurface layers, underground features, determine the depth to bedrock, and investigate indications of the causes of collapse of the constructed Chaq-Chaq dam. The Res2Dinvx64 program used in the inversion method to obtain true 2D resistivity sections using a Schlumberger-Wenner array, which is highly sensitive to changes in resistivity both vertically and laterally. Based on the resistivity values, it was found that the area consists of three geological layers; the first layer consists of soil, while the second layer consists of rock fragments, the interface between them has disappeared because the first layer is thin, and the third layer is specified as consolidated and cohesive limestone of the Kometan Formation. The surface of the Kometan limestones is irregular due to weathering and faulting resulting from tectonic movements leading to the collapse of the area and later filled with sediments of recent deposition. The IP method was only used to distinguish clay and water. According to IP values, water is present in the subsurface of the study area. According to the ERT sections, a sinkhole with a depth range of (15 – 39 m) was encountered at the beginning of most of the profiles.

Mussel-inspired polydopamine (PDA)-grafted 2D-Ti3C2 MXene nanosheets tailored ZnAl-layered double hydroxides (LDH); Toward designing a smart self-healing epoxy composite coating

The constant challenge of corrosion significantly compromises the durability and functionality of metal substrates, propelling the demand for advanced protective solutions. This study introduces a novel smart epoxy coating system modified with a three-component nanocomposite integrating polydopamine (PDA)-modified Ti3C2 MXene with ZnAl-layered double hydroxides (LDH), intercalated with phosphate (P) and glutamate (Gl) ions as corrosion inhibitors. The innovative approach leverages the synergistic impacts of barrier protection, ion exchangeability, and self-healing capabilities to offer superior anti-corrosion performance. In the solution phase, the EIS results revealed a notable increase in resistance values, with MPLG samples exhibiting a 2.45-fold and MPLP samples a 2.17-fold enhancement compared to the blank specimen after 96 h of immersion. Furthermore, the data obtained from EIS demonstrated a significant enhancement in the barrier effects of the epoxy coating upon the addition of MPLG and MPLP. This enhancement was evidenced by a significant increase in the impedance values, which were observed to be 103-fold higher following a prolonged immersion period of 140 days. The self-healing properties, confirmed through EIS, FE-SEM, and EDX/Mapping analyses, indicated the formation of a stable corrosion-protective layer over the damaged areas, thus providing active protection. Adhesion assessments further underscored the coatings' durability, with MPLG and MPLP samples demonstrating minimal delamination. Collectively, these findings emphasize the potential of the proposed PDA-modified MXene@ZnAl-LDH nanocomposite as a multifaceted solution to corrosion challenges, promising significant advancements in the longevity and reliability of coated metal surfaces.

Interfacial Regulation of Rice-Grain-like Iron-Nickel Phosphide Nanorods on Phosphorus-Doped Graphene Architectures as Bifunctional Electrocatalysts for Water Splitting.

The design of bimetallic metal-organic frameworks (MOFs) with a hierarchical structure is important to improve the electrocatalytic performance of catalysts due to their synergistic effect on different metal ions. In this work, the catalyst comprises bimetallic iron-nickel MOF-derived FeNi phosphides, intricately integrated with phosphorus-doped reduced graphene oxide architectures (FeNi2P-C/P-rGA) through the hydrothermal and phosphating treatments. The hierarchical architecture of the catalyst is beneficial for exposing active sites and facilitating electron transfer. The FeNi2P-C/P-rGA catalyst exhibits excellent performance in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline electrolytes. Notably, FeNi2P-C/P-rGA requires only the overpotential of 93 and 210 mV to achieve a current density of 10 mA cm-2 for the HER and OER with small values of Tafel slope and charge transfer resistance, respectively. Furthermore, the catalyst exhibits boosted activity for overall water splitting with a low potential of 1.56 V. This work can be considered to extend the design of multilevel catalysts in the application of water splitting.

Does Breast Feeding Protect Mothers From Obesity?

Hepatosteatosis, which we frequently observe today with change in lifestyle, is often unnoticed, but preventable and reversible; if not prevented, it can lead to serious comorbidities. There is contradicting evidence in the literature; we believe that breastfeeding has a protective effect on hepatosteatosis. In this cross-sectional study we conducted, we aimed to examine the relationship between breastfeeding duration, metabolic parameters and fatty liver. We examined the data of 135 patients aged 20-40 years who have had at least one pregnancy and were admitted to our polyclinic. Forty-five healthcare staff who never breastfed were included in the control group. Measurements of height and weight were taken, and number of children and total breastfeeding time were questioned. Blood values were measured to calculate insulin resistance, non-alcoholic fatty liver disease (NAFLD) fibrosis score and Fibrosis-4 (FIB-4) score. Consequently, there was no significant correlation between total breastfeeding time and body mass index (BMI), NAFLD fibrosis score, Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) value and hemoglobin A1C (HbA1C). When two groups were formed as patients breastfeeding for less than six months and patients breastfeeding for more than six months, a significant difference in BMI was observed between these two groups (p: 0.02). There was a significant relationship between BMI and NAFLD (p: 0.00) and HOMA-IR (p: 0.00). It was observed that there was a significant difference between BMI FIB-4 and NAFLD fibrosis scores of the control group and breastfed group. Lactation should be maintained for at least six months for maternal health together with the baby's health, and more comprehensive studies should be conducted for long-term data.

Study on the predictions of acoustic characteristics of microspeakers based on the specific airflow resistance of ventilation materials: Mesh type

In this study is presented a method for predicting the acoustic characteristics of microspeakers with mesh-type ventilation materials that combines specific airflow resistance with equivalent circuit model. The specific airflow resistances of eight types of ventilation materials were quantified using a self-made measurement system. These materials were then used to simulate the acoustic properties of 40 φ and 20 φ microspeakers, respectively. The results were compared with simulation results obtained using Dr. Maa’s porous plate acoustic impedance and actual measurements. After applying a stable correction factor, the self-made measurement system accurately determined specific airflow resistance values with high reproducibility and stability. A regression curve based on scanning electron microscope obtained porosity and measured specific airflow resistance effectively predicted the specific airflow resistance of materials with known porosity. Applying these values to acoustic simulations, the proposed method significantly improved accuracy, outperforming Dr. Maa’s method by a factor of six, and closely matched actual measurements. This innovative approach is versatile and applicable to various conditions and types of ventilation materials, as well as enhances predictions of their impact on electro-acoustic product performance.

NON-DESTRUCTIVE METHODS OF ESTABLISHING A CAUSE-AND-EFFECT RELATIONSHIP BETWEEN WATER SUPPLY NETWORK ACCIDENTS AND THE CONDITIONS FOR PRESERVING ARCHITECTURAL HERITAGE

Accidents on water supply networks have the most significant negative consequences on the state of the historical and architectural heritage, which was formed over many centuries. The paper analyzes the cause-and-effect relationship between accidents of water-carrying networks and the conditions of architectural heritage preservation using the example of the Kyiv-Pechersk Lavra. The results of determining waterlogging zones and their factors by non-destructive monitoring methods on the territory of the Metropolitan Garden of the Upper Lavra are given. This area combines complex engineering and geological conditions and technogenic mastering, creating conditions for developing dangerous engineering and geological processes and emergency situations. In terms of danger, the garden’s territory belongs to unstable areas for preserving historical monuments of the UNESCO world heritage. The last accident on the water supply networks occurred in October 2022. It caused sinkholes on the surface, rising groundwater levels, significant destruction of an underground structure of historical importance – the Metropolitan Cellar. The research was carried out using the methods of electrotomography and natural electric field. The results of electrotomography were interpreted using two- and three-dimensional models. The existence of an anomalous dome (soils of low resistance), which is observed in the central part of the site, is probably the focus of waterlogging of the soil massif as a result of an accident on the heating network. The analysis of the adapted 3D model based on the results of non-destructive methods of monitoring the geological environment made it possible to indirectly establish the places of unsatisfactory technical condition of engineering networks (cold water supply), where a wetted section with low values of apparent resistance was recorded. Research has confirmed the presence of an inflow of man-made waters (leaks) from main water supply networks in the western part of all profiles as a constant source and factor of waterlogging of the array of soil bases of architectural monuments – Monastyrski walls, Kushnyka tower, etc. Based on the research results, the need to develop compensatory measures to strengthen part of the fortress walls was proposed, and a safe distance for moving networks from historical objects was substantiated to preserve them.

A Straightforward Method to Estimate Battery's Condition Based on Its Internal Resistance Value

A battery condition monitor can be realized using several methods. Some of these methods have been proven to be more reliable than others. In this study, we focus on assessing a battery's condition based on its internal resistance value using a direct current method (DCM). We developed a simple, fast, and straightforward method, including the necessary equipment for this purpose. Only measurements of the battery's terminal (open-circuit) voltage and battery voltage under a certain load are required. We measured around 100 non-rechargeable AA batteries (double-A batteries) and estimated their internal resistances. Both alkaline and lithium-based batteries were tested. Our measurements show that measuring the terminal voltage (open-circuit voltage) alone does not provide an accurate enough status of a battery's condition or state-of-health, SoH. Especially when the battery condition is declining, the internal resistance value gives a better estimation of the battery's condition and usability.

Ceramic Nanotubes—Conducting Polymer Assemblies with Potential Application as Chemosensors for Breath Ammonia Detection in Chronic Kidney Disease

This paper describes the process of producing chemosensors based on hybrid nanostructures obtained from Al2O3, as well as ZnO ceramic nanotubes and the following conducting polymers: poly(3-hexylthiophene), polyaniline emeraldine-base (PANI-EB), and poly(3, 4-ethylenedioxythiophene)-polystyrene sulfonate. The process for creating ceramic nanotubes involves three steps: creating polymer fiber nets using poly(methyl methacrylate), depositing ceramic films onto the nanofiber nets using magnetron deposition, and heating the nanotubes to 600 °C to burn off the polymer support completely. The technology for obtaining hybrid nanostructures from ceramic nanotubes and conducting polymers is drop-casting. AFM analysis emphasized a higher roughness, mainly in the case of PANI-EB, for both nanotube types, with a much larger grain size dimension of over 5 μm. The values of the parameter Rku were close or slightly above 3, indicating, in all cases, the formation of layers predominantly characterized by peaks and not by depressions, with a Gaussian distribution. An ink-jet printer was used to generate chemiresistors from ceramic nanotubes and PANI-EB structures, and the metallization was made with commercial copper ink for printed electronics. Calibration curves were experimentally generated for both sensing structures across a wider range of NH3 concentrations in air, reaching up to 5 ppm. A 0.5 ppm detection limit was established. The curve for the ZnO:PANI-EB structure presented high linearity and lower resistance values. The sensor could be used in medical diagnosis for the analysis of breath ammonia and biomarkers for predicting CKD in stages higher than 1. The threshold value of 1 ppm represents a feasible value for the presented sensor, which can be defined as a simple, low-value and robust device for individual use, beneficial at the patient level.

Analysis of semiconductor properties of fabricated graphene materials

Introducing dopant elements into graphene is a crucial process for creating bandgaps, which will have significant importance in developing nanoelectronic devices in the future. In this study, we provide an analysis of the electrical and carrier mobility properties of graphene doped with BN in ratios of 1 %, 3 %, and 5 %, graphene 95 %, ZnO-3 %, and BN2 %, graphene-95 %, Al2O3-3 % and BN-2 %, graphene-95 %, TiO2-3 % and BN-2 % by using a sintering process. Upon analyzing the band structure, it was determined that the mentioned materials demonstrate a bandgap in graphene. The resistivity values for fabricated graphene materials doped with different nanoparticles are estimated using the Source-meter Unit (SMU) at room temperature (25°C), 100°C and 200°C. The conductivity of graphene is 8.93E+07 Ω−1cm−1 and reduced gradually with the doping percentages. The resistivity of graphene is measured at 1.12 E-08 Ω.cmand increases with the doping percentages, and carrier mobility is measured to be 9239 cm2V−1s−1 and gradually reduced with the doping percentages. The temperature-dependent conductivity is determined using electrical conductivity under the constant relaxation time approximation.