Low Resistance Research Articles

Outcomes of dietary alpha-lipoic acid on testicular vascularization, steroid hormones, and seminal quality in aged Baladi bucks

BackgroundSenescence is accompanied by a progressive decrease in male reproductive performance, mainly due to oxidative stress and endothelial dysfunction. Alpha lipoic acid (ALA) is a potent antioxidant, that diffuses freely in aqueous and lipid phases, possessing anti-inflammatory and anti-apoptotic properties. This study aimed to examine the effects of supplemental dietary ALA on testicular hemodynamics (TH), circulating hormones, and semen quality in aged goats. Twelve Baladi bucks were divided into two groups (n = 6 each); the first fed a basic ration and served as a control group (CON), while the second received the basic ration supplemented with 600 mg ALA/ kg daily for consecutive eight weeks (ALA).ResultsThere were improvements in testicular blood flow in the ALA group evidenced by a lower resistance index (RI) and pulsatility index (PI) concurrent with higher pampiniform-colored areas/pixel (W3-W6). There were increases in testicular volume and decreases in echogenicity (W3-W5; ALA vs. CON). Compared to the CON, ALA-bucks had higher serum concentrations of testosterone, estradiol, and nitric oxide (W3-W5). There were enhancements in semen traits (progressive motility, viability, morphology, and concentration, alanine aminotransferase enzyme) and oxidative biomarkers (catalase, total antioxidant capacity, and malondialdehyde).ConclusionsALA dietary supplementation (600 mg/kg diet) improved aged bucks’ reproductive performance by enhancing the testicular volume, testicular hemodynamics, sex steroids, and semen quality.

Humidity sensitive memristor based on Ni–Al layered double hydroxides

Reaping the advantages of their exceptional humidity-sensitive elements, humidity sensors exhibit a remarkable ability to adapt to alterations in ambient moisture levels. The significance of the humidity sensor in biological detection is progressively growing, owing to this characteristic. This work examines the impact of humidity on the resistive switching properties Ni–Al layered double hydroxides (LDHs) memristor. As the porous Ni–Al LDHs material contains a significant number of hydroxyl groups, the Ni–Al LDHs memristor exhibits remarkable sensitivity to changes in humidity. As the relative humidity level increases, a conspicuous decrease is observed in resistance of low resistance state, which attributed to the transition of protons facilitated by water. The humidity detection range of the Ni–Al LDHs memristor is from 30 RH% to 95 RH%, and it exhibits a sensitivity of 101.72 mV/RH. The Ni–Al LDHs memristor exhibits humidity sensitive resistive switching characteristics. In different humidity environments can produce a dynamic change between high and low resistance state switching. An artificial humidity sensing system by utilizing the unique resistance change behavior in Ni–Al LDHs memristor induced by humidity was demonstrated.

The impacts of thermocouple insulation failure on the accuracy of temperature measurement data in forensic fire-death scenarios-Part I: Physical disintegration.

Thermocouples are utilized to monitor a wide range of temperatures in industrial applications. They are also used in both fire and forensic science research to measure temperatures of fires and of materials exposed to fire. Taking accurate temperature measurements during forensic fire-death scenarios is very difficult due to direct fire exposure to thermocouples, shrinkage and destruction of tissues, and movements from pyre collapse and pugilistic posturing of human donors. This two-part study investigates the impacts on the accuracy of temperature data if the selected thermocouples are unable to withstand fire exposure. Part I (this article) provides an overview of thermocouple theory along with evidence of the physical deterioration that occurs when glass fiber-insulated thermocouple wires are overheated by exposure to fire-level temperatures in a muffle furnace. This study verified that insulation overheating causes embrittlement and disintegration, which can cause the indicated temperature to reflect a new location of measurement located far away from the original measuring junction at the thermocouple tip. Part II will discuss the measurement errors that occurred due to low electrical resistance of insulation when three different thermocouple models were passed through fire-level temperatures to measure an ice bath at a constant temperature of 0°C.

The impacts of thermocouple insulation failure on the accuracy of temperature measurement data in forensic fire-death scenarios-Part II: Low electrical resistance and contamination.

Part II of this two-part article investigates the impact of thermocouple insulation failure on temperature measurement data in forensic fire-death scenarios. Two different models of glass fiber-insulated thermocouple wires (GG-K-24-SLE and HH-K-24 from Omega Engineering) were passed through a ceramic kiln at temperatures up to 1093°C to measure an ice bath at a constant 0°C. In a separate experiment, the same two models of thermocouple wire plus a BLMI-XL-K-18U-120 mineral-insulated metal-sheathed thermocouple probe were passed through a wood pallet fire to measure an ice bath. In the ceramic kiln, the effect on measurement errors was determined for short vs. long exposure lengths and clean insulation vs. insulation contaminated with pork fat. Glass fiber-insulated thermocouple wires showed severe failure in both experiments, with errors ranging from -270°C to almost 2200°C. The metal-sheathed probe showed no evidence of insulation failure and continued to accurately measure the ice bath temperature within expected margins of error around 0°C. This study highlights how exposure of inadequate thermocouples to fire-level temperatures produces severe errors in temperature data. Consequently, it will not be possible to use this data to draw any accurate conclusions about the effects of fire exposure to human donors or animal proxies.

Elevated pulse pressure preceded incident chronic kidney disease in the general older population in Sweden

Arterial stiffness (AS) and chronic kidney disease (CKD) are common in the older population. AS results in increased pulsatile pressure, elevated pulse pressure (PP), and is linked to hypertension. PP is a surrogate for AS. The kidney has low vascular resistance mechanisms, presumably making it vulnerable to the increased pulsatile pressure and hypertension associated with AS. The aims of this study were to investigate the impact of PP elevation on incident CKD (glomerular filtration rate < 60 ml/min/1.73 m2) and all-cause mortality. The data was collected from the general population cohort study “Good Aging in Skåne”. Cox proportional hazard regression models adjusted for age, sex, diabetes, and smoking habits were used to investigate the impact of three levels of PP elevation on incident CKD (n = 2693) and all-cause mortality (n = 5253). For PP < 60 mmHg, the median survival time was 18.7 years (event incident CKD) and first quartile survival time (event all-cause mortality) 15.4 years. Elevated PP ≥ 80 mmHg was associated with incident CKD (hazard ratio 1.59, CI 1.28–1.97), but not all-cause mortality. Our results suggest that a finding of PP ≥ 80 mmHg in older age should raise concern of kidney function.

Morphological Characteristics of Colon Tumors in Mice with Different Tolerance to Hypoxia.

In adult male C57BL/6 mice with high (HR) and low (LR) resistance to hypoxia, morphological features of colon tumors and blood parameters were evaluated 70 days after intraperitoneal injection of azoxymethane and subsequent consumption of 3 cycles of dextran sulfate sodium. On macroscopic analysis, tumors were found in the distal colon in 35% (7 of 20 animals) of HR and 31% (4 of 13 animals) of LR animals. Microscopic analysis of the distal colon revealed tumors in 75% (15 of 20 animals) of HR and 69% (9 of 13 animals) of LR mice. The tumors were presented by areas of glandular intraepithelial neoplasia and adenocarcinomas; the incidence and the area of the tumors did not differ in groups of HR and LR mice. The number of neuroendocrine and goblet cells in the distal colon mucosa in the areas of tumors was similar in the compared groups. However, in both HR and LR mice of the experimental groups, the content of goblet cells in tumors was lower and the content of endocrine cells was higher than in the corresponding control groups. In the peripheral blood, the erythrocyte count and hemoglobin content decreased in HR and LR mice of the experimental groups; the relative number of monocytes increased only in HR mice and the absolute number of lymphocytes and monocytes decreased in LR mice. Thus, 70 days after azoxymethane administration and dextran sulfate sodium consumption, the tumors in mice were presented by glandular intraepithelial neoplasia and adenocarcinomas, and their incidence and area did not differ between animals with different tolerance to hypoxia.

Defining Design Parameters for Controlled Rocking Braced Frames to Control Seismic Losses

ABSTRACT Controlled rocking braced frames (CRBFs) are a self-centering lateral force-resisting system aimed at reducing structural damage potential. Previous research has shown that relatively low design forces for rocking and for structural elements in CRBFs would be acceptable based on collapse fragility analysis. However, past studies have also highlighted the potential for significant story drifts and for increased demands on acceleration-sensitive nonstructural components installed in buildings with CRBFs. Therefore, while CRBFs have demonstrated acceptable performance in terms of collapse across a wide range of design options, these design options must be evaluated considering the performance of nonstructural components if the intended low-damage potential of CRBFs is to be fully realized. To address this need, this paper investigates the influence of two key design parameters on seismic losses of buildings with CRBFs, namely the response modification factor (R) for the rocking joint design and the amplification factor (γ) used to incorporate higher-mode forces into the capacity design of frame members. Three different heights of CRBF buildings are designed using different design options, with values of R ranging from 5 to 12 and with higher-mode forces considered based on two seismic intensity levels: the design earthquake (DE) and the maximum considered earthquake (MCE). Then, following an assessment of structural responses, the paper’s primary emphasis is on earthquake-induced economic losses. While the computed total expected annual losses (EALs) using various design options are remarkably similar, the distribution of losses attributed to collapse or to nonstructural components varies. The CRBFs with lower resistance to rocking exhibit greater losses attributed to collapse and to drift-sensitive nonstructural components, but this is counterbalanced by a simultaneous reduction in losses related to acceleration-sensitive nonstructural components. Furthermore, in taller CRBF buildings, using amplified higher-mode forces based on the MCE level slightly decreases total EALs compared to those using the DE level, primarily due to a reduction in collapse losses.

Numerical Analysis of Combined Effect Hybrid Fibres and Fire Insulation on the Fire Resistance Performance of SCC Beams

The use of self-compacting concrete in structural members has become increasingly prevalent in various construction applications. However, these structures are susceptible to one of the most hazardous disasters, which is the fire. This paper presents a numerical investigation of the fire resistance performance of self-compacting reinforced concrete (SCC) beams, as well as a parametric study to assess the impact of hybrid fibres and fire insulation on enhancing their performance under fire conditions. The study is conducted by developing a 3D finite element (FE) model using ANSYS software, where temperatures are applied according to the ISO834 standard fire. Geometric and material nonlinearities are considered in the evaluation of the behaviour of beams under fire conditions. The developed FE model is validated by comparing the predicted results with those of the experimental tests in literature. The fire resistance performance of SCC beams was compared with that of normal strength concrete (NSC) beams. The parametric study is conducted using three types of fire insulation, namely Tyfo WR-AFP, CAFCO 300, and Carboline Type-5MD. The results showed that SCC beam has lower fire resistance performance than the NSC beam. However, the incorporation of hybrid fibres allows a 17% improvement in the fire resistance of SCC beams. The use of fire insulations has increased the fire resistance time of SCC beams, and more particularly Carboline Type-5MD insulation with an increase of 28%. The combined use of hybrid fibres and fire insulation improved the fire resistance of SCC beams by 43%.

Intrinsically Safe Lithium Metal Batteries Enabled by Thermo-Electrochemical Compatible In Situ Polymerized Solid-State Electrolytes.

In situ polymerized solid-state electrolytes have attracted much attention due to high Li-ion conductivity, conformal interface contact, and low interface resistance, but are plagued by lithium dendrite, interface degradation, and inferior thermal stability, which thereby leads to limited lifespan and severe safety hazards for high-energy lithium metal batteries (LMBs). Herein, an in situ polymerized electrolyte is proposed by copolymerization of 1,3-dioxolane with 1,3,5-tri glycidyl isocyanurate (TGIC) as a cross-linking agent, which realizes a synergy of battery thermal safety and interface compatibility with Li anode. Functional TGIC enhances the electrolyte polymeric level. The unique carbon-formation mechanism facilitates flame retardancy and eliminates the battery fire risk. In the meantime, TGIC-derived inorganic-rich interphase inhibits interface side reactions and promotes uniform Li plating. Intrinsically safe LMBs with nonflammability and outstanding electrochemical performances under extreme temperatures (130°C) are achieved. This functional polymer design shows a promising prospect for the development of safe LMBs.

Carbon and water vapor exchanges coupling for different irrigated and rainfed conditions on Andean potato agroecosystems

AbstractThe fundamental exchange of water for carbon lays the groundwork for understanding the interplay between carbon and water cycles in terrestrial ecosystems, providing valuable insights into global water and carbon balances and vegetation growth. Inherent water use efficiency (IWUE) was used as a study framework of the diurnal patterns and degree of coupling of carbon and water exchange to investigate the net ecosystem carbon exchange (NEE) responses of three water regime potato cropping systems [full-irrigation (FI), deficit-irrigation (DI), and rainfed (RF)] in Cundinamarca, Colombia. The eddy covariance method was used to determine CO2 and water fluxes, surface resistances, and the omega decoupling factor (Ω). Additionally, leaf area index (LAI), and specific leaf area (SLA) were assessed to determine the canopy influence on carbon and water exchange. The highest carbon sink activity (NEE = -311.96 ± 12.82 g C m−2) at FI, is primarily attributed to a larger canopy with high autotrophic activity and low internal resistance. This supported a highly coupled and synchronized exchange between evapotranspiration (ET) and gross primary production (GPP), as reflected in the highest IWUE (4.7 mg C kPa s−1 kg−1 H2O). In contrast, the lower sink capacity at DI (NEE = − 17.3 ± 4.6 g C m−2) and the net carbon source activity from RF (NEE = 187.21 ± 3.84 g C m−2) were related to a smaller leaf area available for water and carbon exchange, resulting in lower IWUE (2.3 and 1.01 mg C kPa s−1 kg−1 H2O, respectively) and a decoupled and desynchronized gas exchange caused by unbalanced restrictions on ET and GPP fluxes. These results provide new information on carbon–water interactions in potatoes and improve the understanding of carbon sequestration and drought effects on potato sink activity.

Ultra‐High Peak Power Generation for Rotational Triboelectric Nanogenerator via Simple Charge Control and Boosted Discharge Design

AbstractCurrently, enhancing the output power of rotational‐mode triboelectric nanogenerators (TENGs) using various complicated systems is a contentious issue; however, this is a challenging process owing to the inherent characteristics of TENGs, namely, low output currents as opposed to high voltages. Thus, this study proposes a simple and innovative strategy for ultra‐high output peak power generation of TENGs called a self‐boosted rotational electrostatic‐discharge TENG (SRE‐TENG). The SRE‐TENG mechanism is unique as it is based on charge control and boosted discharge design, thereby achieving a remarkable peak power of 1103.8 W, peak power density of 140.6 Kw m−2, low optimum resistance of 100 Ω, and broad peak power generation range of 10 Ω to 1 GΩ. Diligent measurements and analyses of the peak and root‐mean‐square voltage and current outputs of the SRE‐TENG are conducted for various design variables and circuit configurations. The proposed SRE‐TENG mechanism is validated using experimental and multiphysics simulation results. The high‐output performance of the SRE‐TENG is demonstrated via the lighting of 3,000 LEDs and a 60‐W lamp array, continuous driving of a commercial sensor array, and hydrogen/oxygen generation via water electrolysis.

Large-area and few-layered 1T'-MoTe2 thin films grown by cold-wall chemical vapor deposition.

This study employs cold-wall chemical vapor deposition to achieve the growth of MoTe2thin films on 4-inch sapphire substrates. A two-step growth process is utilized, incorporating MoO3and Te powder sources under low-pressure conditions to synthesize MoTe2. The resultant MoTe2thin films exhibit a dominant 1T' phase, as evidenced by a prominent Raman peak at 161 cm-1. This preferential 1T' phase formation is attributed to controlled manipulation of the second-step growth temperature, essentially the reaction stage between Te vapor and the pre-deposited MoOx layer. Under these optimized growth conditions, the thickness of the continuous 1T'-MoTe2films can be precisely tailored within the range of 3.5 - 5.7 nm (equivalent to 5 - 8 layers), as determined by atomic force microscopy depth profiling. Hall-effect measurements unveil a typical hole concentration and mobility of 0.2 cm2/V-s and 7.9 × 1021cm-3, respectively, for the synthesized few-layered 1T'-MoTe2 films. Furthermore, Ti/Al bilayer metal contacts deposited on the few-layered 1T'-MoTe2films exhibit low specific contact resistances of approximately 1.0 × 10-4Ω-cm2estimated by the transfer length model. This finding suggests a viable approach for achieving low ohmic contact resistance using the 1T'-MoTe2intermediate layer between metallic electrodes and two-dimensional semiconductors.

Autonomous Thermal Modulator Based on Gold Film‐Coated Liquid Crystal Elastsomer

AbstractRadiative cooling has been recently intensively explored for thermal management and enhancing energy efficiency. Yet, traditional materials with singular emissivity fall short in dynamic thermal management, highlighting the need for materials that can adjust their thermal radiation in real time. Active modulation methods, requiring external stimuli such as mechanical stretch, electric potential, or humidity change, offer adaptability but can increase energy use and complexity. Passive approaches, using materials' inherent thermal‐responsive properties, face manufacturing and scalability challenges. Here, a scalable yet effective passive approach is introduced for adaptive thermal modulation based on gold (Au) and liquid crystal elastomer (LCE) with a reversible response to environmental temperature changes. This modulator enables a “low thermal resistance” state through actuation‐induced microcracks that expose a high‐emissivity polymer substrate, and a “high thermal resistance” state by closing these microcracks and forming a high thermal resistance air gap between the modulator and the target object. The flexible design and fixed external dimensions of the Au‐LCE thermal modulator make it adaptable to various surface geometries. Furthermore, by adjusting the LCE's chemical composition, the modulator's transition temperature can be tailored, broadening its applications from enhancing building energy efficiency to improving clothing thermal comfort.

Recent progress in the development of coatings for paper food packaging applications

Relevance and aim of the research: Many types of coatings have been developed to meet the demanding needs and properties of paper-based packaging, which is the most widely used sustainable category of food packaging. The purpose of this paper is to list and classify special sustainable coatings, such as bio-based coatings and coatings based on nanomaterials (NPs) that provide barrier, optical, mechanical, anti-microbial and other properties as well as additional functions to the final product for food paper packaging. Methodology and results: The study is an overview of the previously published works on trends and challenges in the development of healthy and eco-friendly for sustainable food paper packaging applications, which are green alternatives to conventional coatings. As known, paper/paperboard packaging, because of its structure made from cellulose fibers, is naturally sensitive to microbial attack due to the poor barrier properties (i.e., hydrophilicity, porosity, low grease resistance, high absorptivity to gases and water vapors). Thus, paper packages must be properly coated to withstand and keep the food safe, preventing temperature, humidity and other factors of the surrounding from affecting the composition of packaged food. However, the current market is based on the application of commonly used coatings, which are typically made from fossil oil or synthetic polymers, waxes and /or fluor-derivatives that improve surface hydrophobicity and barrier properties. Nowadays, the use of these materials is limited because of problems arising from fossil-oil resources, poor recyclability, and environmental issues. Therefore, these coatings must be replaced by new materials, with high biodegradability, recyclability and compostability features. Recent studies are focused on biopolymers including polysaccharides such as chitosan, starch, etc., proteins such as whey, wheat gluten, and zein, polyesters as polylactic acid (PLA), polycaprolactone (PCL), and polyhydroxyalkanoates (PHAs) that are investigated to formulate coatings with barrier properties for food packaging paper. Petroleum-based polymers are commonly used in paper coating. Due to the good affinity with the substrate, they create suitable barriers to gases and aroma and increase the mechanical strength of the paper packaging. Moreover, biopolymer products have been developed as counterparts to smoothly replace petroleum-based polymers., they can be made from natural raw materials and sources, such as vegetal and marine biomass, this way they can be biodegradable, nontoxic. Additionally, they act as a basis for the incorporation of additives with specific functions for coated paper (ie, active-antimicrobial properties). The methods of chemical modification and combination as well as the processing and production of these new coatings for paper packaging are still under investigation. The addition of certain nanoparticles (NPs) such as metals and oxides in biopolymers and green coatings could be advantageous to add value and enhance the processing, performance and functionality of food paper packaging. Conclusions &amp; practical implications: The application of coatings on paperbased food packaging is extensively investigated to replace petrochemical derivatives by choosing environmentally friendly alternatives that come from natural and renewable resources. These options determine the ultimate recyclability, biodegradability and even compostability of the final product. The incorporation of certain nanomaterials in the coatings promises to provide a wide range of enhanced properties and improve barrier characteristics of the paper-based food packaging.

Efficient In Situ Doping of Strained Germanium Tin Epilayers at Unusually Low Temperature

AbstractEfficient p‐ and n‐type in situ doping of compressively strained germanium tin (Ge1‐xSnx) semiconductor epilayers, grown by chemical vapor deposition on a standard Si(001) substrate, is demonstrated. Materials characterization results reveal unusual impact of dopants manifesting via a pronounced reduction of Sn content in the epilayer, accompanied by an enhancement of the growth rate, due to increasing p‐type doping concentration. Furthermore, the opposite behavior for n‐type doping is observed, resulting in a less pronounced increase of Sn concentration and no effect on growth rate. Nevertheless, a very high density of electrically active holes up to ≈4 × 1020 cm−3 is obtained in p‐type doped Ge1‐xSnx epilayer resulting in the lowest resistivity of 0.15 mΩ cm among all in situ doped epitaxial and strained group‐IV semiconductors. Also, the metal‐to‐insulator transition in Ge1‐xSnx is experimentally demonstrated for doping levels above 1 × 1017 cm−3, which is substantially lower than in any group‐IV semiconductor, and theoretically predict it to be as low as ≈1 × 1017 cm−3. The findings enabled by the doping regime explored in this work can open novel prospects to engineer low resistivity contacts and charge current injection in applications covering next‐generation transistors, qubits, diodes, electrically driven light sources, sensors and hybrid quantum devices.

Sol-Gel Derived ZnO Thin Films with Nonvolatile Resistive Switching Behavior for Future Memory Applications

Herein we report on a facile sol-gel spin-coating technique to fabricate ZnO thin films that grow preferentially along the (002) plane on FTO substrates. By employing the magnetron sputtering technique to deposit a tungsten (W) top metal electrode onto these ZnO thin films, we successfully realize a W/ZnO/FTO memory device that exhibits self-rectifying and forming-free resistive switching characteristics. Notably, the as-prepared device demonstrates impressive nonvolatile and bipolar resistive switching behavior, with a high resistance ratio (RHRS/RLRS) exceeding two orders of magnitude at a reading voltage of 0.1 V. Moreover, it exhibits ultralow set and reset voltages of approximately +0.5 V and −1 V, respectively, along with exceptional durability. In terms of carrier transport properties, the low resistance state of the device is dominated by ohmic conduction, whereas the high resistance state is characterized by trap-controlled space-charge-limited current conduction. This work highlights the potential of the ZnO-based W/ZnO/FTO memory device as a promising candidate for future high-density nonvolatile memory applications.

High corrosion-resistance and electrical-conductivity phytic acid/permanganate composite coating on AZ31 magnesium alloy

A composite coating based on phytic acid and permanganate was developed on AZ31 magnesium alloy via two-step chemical conversion process, exhibiting high corrosion resistance and low contact resistance. The morphology, composition, anti-corrosion properties and electrical properties of the composite coating were characterized. The composite coating was mainly composed of magnesium phytate, MnO2 and Mn2O3. The corrosion protective efficiency of the composite coating is 80.25 %, which is higher than that of the phytic acid coating and potassium permanganate coating. Furthermore, the composite coating shows low electrical contact resistance around 0.083 Ω cm2, which is close to the potassium permanganate coating but much higher than the phytic acid coating. The high corrosion resistance and electrical conductivity of the composite coating can be attributed to the growth of conductive manganese oxide at the cracks or pores of the anti-corrosion phytic acid coating.

Extraordinary photoexcitation of semimetal 1T'-MoTe2 inducing ultrafast charge transfer in lateral 2D homojunction

Exploring novel and more efficient photoexcitation transition mechanisms in two-dimensional transition metal dichalcogenides (TMDCs) is crucial for the advancement of high-performance optoelectronic devices. In this study, an extraordinary photoluminescence (PL) phenomenon is discovered that originates from a vertical transition between specific bands in the X-point energy valley of K-space in multilayer Weyl semi-metal monoclinic (1T') MoTe2 without a gap structure. This effective transition is independent of the bandgap and is unaffected by the number of layers in 1T'-MoTe2, breaking the limitations of traditional TMDCs semiconductor materials and promoting the development of advanced two-dimensional (2D) semimetal-based optoelectronic devices. In a lateral multilayer 1T'-MoTe2-2H hetero-phase homojunction, a record ultrafast transfer of photogenerated charges up to 25 fs is achieved. The highly efficient interband transition, small conduction band energy level difference (less than 100 meV), and exceptionally strong e-p coupling synergistically promote the ultrafast transfer of photo-generated charges. Together with the merits of multilayer 1T'-MoTe2 such as higher carrier densities and lower resistance, these findings open the door to potentially ultra-high performance optoelectronic applications.

Microstructure Analysis, Piezoelectrical Resistivity, and Compressive Strength Concrete Incorporated with Waste Steel Slag as a Fine Aggregate Replacement

Abstract This study aims to investigate the effect of waste steel slag (SS) as partially replaced with cement and fine aggregate on conventional concrete for different mixes named M25, M35, and M47 in terms of compressive strength (CS), electrical resistivity (ER), and piezoresistivity behavior. SS is a molten mixture of silicates and oxides that solidifies upon cooling, a byproduct of the steel-making process. Before doing the design experiments, the optimum value of SS as powder and fine aggregate was determined using seven different mixes to investigate the effect of different SS sizes on the CS and piezoresistivity of normal concrete. Based on the results achieved, the optimum value and size of SS were selected to modify and investigate the effect of SS on three different mixes of conventional concrete named M25, M35, and M47 in terms of CS, ER, and piezoresistivity behavior. The resistivity of all concrete mixes was measured using four-probe from early curing to 28 days of curing time. The results demonstrated that M47 mix modified with SS has lower resistivity than the rest of the concrete mixes. The results of piezoresistivity behavior indicated that M47 mix modified with SS has a higher resistivity change while applying stress at 3 days of curing compared to the M25 and M35 concrete mix modified with SS by 44.1 % and 37.6 %, respectively. The Vipulandanan p-q model was applied to predict both ER versus time and change of resistivity versus stress for all mixes. The results demonstrated that the model predicted the change of resistivity versus applied stress with a high coefficient of determination that varied between 0.82 and 0.989, and a low root mean square error changed between 0.81 Ω.m and 7.94 Ω.m.

Human footprint and rainfall shape Masai giraffe's habitat suitability and connectivity in a multiple‐use landscape

AbstractGiraffe populations have declined by around 40% in the last three decades. Climate change, poaching, habitat loss, and increasing human pressures are confining giraffes to smaller and more isolated patches of habitats. Masai giraffes (Giraffa tippelskirchi) have been subjected to habitat loss and fragmentation, diseases, poaching, and unpredictable calamities such as wildfires and climate change. In this study, we aimed to identify (1) suitable Masai giraffe habitats within the transboundary landscape of Tsavo‐Mkomazi in Southern Kenya and Northern Tanzania; and (2) key connecting corridors in a multiple‐use landscape for conservation prioritization. We combined Masai giraffe presence data collected through a total aerial survey with moderate resolution satellite data to model habitat suitability at 250 m resolution using species distribution models (SDMs) implemented in Google Earth Engine (GEE). Model accuracy was assessed using area under precision recall curve (AUC‐PR). We then used the habitat suitability index as a resistance surface to model functional connectivity using Circuitscape theory and cost‐weighted distance pairwise methods. Human habitat modification, rainfall, and elevation were the main model predictors of Masai giraffe habitat and corridors. On average, our 10‐fold model fitting attained a good predictive performance with an average AUC‐PR = 0.80 (SD = 0.01, range = 0.79–0.83). The model predicted an area of 15,002 km2 as potential suitable Masai giraffe habitat with over 17% outside protected areas within the landscape. Although Tsavo West National Park formed a key habitat and a key connecting corridor, nonprotected community ranches connecting Tsavo West and Tsavo East National Parks are equally important in maintaining landscape connectivity joining more than two Masai giraffe core areas with low resistance and high permeability. To maintain critical Masai giraffe's habitats and landscape functional connectivity, especially in multiple‐use landscapes, conservation‐compatible land use practices, capacity building, and land use planning should be considered at the outset of any new infrastructure development and land use changes. This modeling shows the potential of utilizing remotely sensed information and ground surveys to guide the management of habitats and their connecting corridors across important African landscapes, complementing existing efforts to identify, conserve, and protect wildlife habitats and their linkage zones.