Resistivity Measurements Research Articles

Sr-Doping-Modulated Metal-Insulator Transition in NdNiO3 Epitaxial Films

Abstract Perovskite-structured nickelates, ReNiO3 (Re = rare-earth), have long garnered significant research interest due to their sharp and highly tunable metal-insulator transition (MIT). Doping the parent compound ReNiO3 compound with alkaline earth metal can substantially suppress this MIT. Recently, intriguing superconductivity has been discovered in doped infinite-layer nickelates (ReNiO2), while the mechanism behind A-site doping-suppressed MIT in the parent compound ReNiO3 remains unclear. To address this question, we grew a series of Nd1-x Sr x NiO3 (x = 0 ~ 0.2) thin films and conducted systematic electrical transport measurements. Our resistivity and Hall measurements suggest that Sr-induced excessive holes is not the primary reason for MIT suppression. Instead, first-principles calculations indicate that Sr cations, with larger ionic radius, suppress breathing mode distortions and promote charge transfer between oxygen and Ni cations. This process weakens Ni-O bond disproportionation and Ni2+/Ni4+ charge disproportionation. Such significant modulations in lattice and electronic structure convert the ground state from a charge-disproportionated antiferromagnetic insulator to a paramagnetic metal, thereby suppressing the MIT. This scenario is further supported by the weakened MIT observed in the tensile-strained NSNO/STO(001) films. Our work reveals the A-side doping-modulated electrical transport of perovskite nickelate films, providing deeper insights into novel electric phases in these strongly correlated nickelate systems.

Effects of lattice instability on the thermoelectric behavior of kagome metal ScV6Sn6

Kagome metal ScV6Sn6 has been a subject of interest due to the emergence of a first-order structural phase transition with intriguing charge density wave behavior below the transition temperature Tc ∼ 92 K. To explore the thermoelectric properties and provide experimental insights into the nature of the phase transition, we have carried out a combined study by means of the electrical resistivity, Seebeck coefficient, and thermal conductivity measurements on single crystalline ScV6Sn6. Pronounced features near Tc have been characterized by all measured physical quantities. In particular, the Seebeck coefficient exhibits a marked reduction as lowering temperature across Tc, attributed to an imbalance of the contribution from different type of carriers induced by the structural phase transition. From the examination of the electronic and lattice thermal conductivities, we obtained a confirmation that the observed enhancement at Tc is essentially caused by the change of the lattice thermal conductivity, demonstrating the primary importance of lattice distortions for the heat transport of ScV6Sn6. In addition, the lattice thermal conductivity above Tc was found to increase monotonically with temperature. We associated the peculiar phenomenon with lattice fluctuations, highlighting the essence of structural instability in the kagome lattice ScV6Sn6. These results add to the knowledge about the thermal transport properties in kagome materials with a hexagonal HfFe6Ge6-type structure.

7700 Two Years Of Testosterone Therapy Reduces Glycemia In Males At High Risk Of Type 2 Diabetes Without Affecting Beta Cell Function: Results From A Randomised Controlled Trial And Cellular Model

Abstract Disclosure: M. Umapathysivam: None. S. Nawaz: None. K. Robledo: None. C.A. Allan: None. K. Bracken: None. M. Grossmann: None. D.J. Handelsman: None. W.J. Inder: None. D. Jesudason: None. B. Stuckey: None. B. Yeap: None. A. Januszewski: None. A. Jenkins: None. A. Conway: None. B. Hastoy: None. G.A. Wittert: Consulting Fee; Self; I-Nova. Grant Recipient; Self; Lawley pharmaceuticals, Bayer, Weight Watchers, Eli Lilly & Company. Speaker; Self; Bayer, Inc., Amgen Inc, Besin Health Care. Background: In the Testosterone for the prevention of type 2 diabetes (T4DM) Study, treatment with testosterone (T)-undecanoate (1000 mg IM 3 monthly) vs placebo decreased fat mass and reduced the risk of T2D by 40% after 2 years. However, the mechanism(s) by which T therapy prevents or reverts T2D remain unclear. Aim: To assess (1) the impact of T treatment on insulin resistance (IR) and beta-cell function in the T4DM study and (2) the in-vitro effect of graded T exposure on glucose stimulated insulin secretion (GSIS) from the human beta-cell line EndoC-βH1. Methods: (1) T4DM study: Men (n= 1007) from the T4DM study aged, 50-74 years, waist circumference (WC) >95cm, with prediabetes, or newly diagnosed T2D (by OGTT) and serum testosterone (T) ≤ 14 nmol/L (chemiluminescent assay) treated with T-undecanoate (1000 mg IM 3 monthly) or placebo for 2 years. Men were included if they had fasting bloods at baseline, weeks 18, 66, and 102 (N=743). We compared the change in glycated albumin, and derived measures of beta-cell function (HOMA2-B) and insulin resistance (HOMA-IR) using fasting glucose and c-peptide in T and placebo treated men using linear regression models.(2) EndoC-βH1 were incubated with T 5nM, 10nM and 15nM for 20 min and 15nM T for 2-days. Insulin secretion and content were measured at baseline (1mM glucose) and after 20 min exposure 20mM glucose. Results: Treatment with T compared to placebo reduced glycated albumin (-3.4 umol/L; 95%CI:1.4-5.4, p<0.001) maximally at week 66, along with C-peptide (corrected for baseline C-peptide and change in fasting glucose) (-0.12 nmol/L;-0.22,-0.02; p=0.01), HOMA2-B (-6.1; 95%CI: -16, 3.7; p=0.2) and HOMA-IR (-0.20; 95%CI: -0.59,0.20; p=0.3). In-vitro, acute exposure of EndoC-βH1 to 5nM and 10nM of T had no effect on GSIS, and 15nM T reduced GSIS (<20%, p=0.002). T, at 15nM for 2 days was without effect on GSIS. EndoC-βH1 insulin content was not altered at any concentration or timeframe of T exposure. Conclusion: In men with pre-diabetes or early T2D, T treatment reduces glycemia without evidence either in vivo or in-vitro of an affect to increase insulin secretion. Presentation: 6/1/2024

Resistance and resilience to tau pathology in Alzheimer's disease: Effects of age, sex, and APOE alleles.

Neurofibrillary tangles (NFTs), a hallmark of tau pathology in Alzheimer's disease (AD), accumulate in the aging brain. However, some individuals remain cognitively intact despite high Braak (III-VI) stages, which characterize NFTs' accumulation. We studied resistance and resilience to tau pathology by assessing Braak stages based on apolipoprotein E (APOE) alleles, sex, and age in a sample of 1932 cognitively intact individuals of European ancestry from the Alzheimer's Disease Sequencing Project (ADSP). Resistance, characterized by low (0-II) Braak stages, was observed in men and women younger than 85 years of age. Resilience, indicated by high (III-VI) Braak stages, increased significantly with age in both men and women for each APOE allele. It became more pronounced, with the proportion of high Braak stages exceeding 50% at 85 years and older in women, irrespective of the APOE allele. The identification of factors underlying resistance and resilience against AD-related pathologies is essential for promoting cognitively healthy aging. We investigated cognitive resistance and resilience to tau pathology in Alzheimer's disease (AD).This study included individuals who were not diagnosed with AD.Braak stages 0-II and III-VI were considered as a measure of resistance and resilience, respectively.Resistance was stronger at ages younger than 85 years in non-carriers of the apolipoprotein E (APOE) ε4 allele.Resilience increased with age for each APOE allele independently of sex.At age 85 years and older, high resilience(>50%) was observed in women regardless of the APOE allele.

TCT-91 Measures of Insulin Resistance and Aortic Valve Calcification in the General Population

TCT-91 Measures of Insulin Resistance and Aortic Valve Calcification in the General Population

Pressure effects on superconductivity in EuSr2Bi2S2.5Se1.5F4 at 1 K

We performed electrical resistivity and X-ray diffraction measurements on the BiS2-based compound, EuSr2Bi2S2.5Se1.5F4, under high pressure using cubic and diamond anvil cells, respectively. We have also measured electrical resistivity at low temperatures and ambient pressures. The superconducting transition temperature (T c) was 1.13 K at ambient pressure and EuSr2Bi2S2.5Se1.5F4 was found to behave like a superconductor. Upon the application of increased pressure, T c increased and then decreased again, which was attributed to the structural phase transitions that accompany increased pressure in EuSr2Bi2S2.5Se1.5F4 superconductors.

Improved flux pinning properties of Mg exceed MgB2 ceramics with B4C and Dy2O3 additions

In this study, MgB2 polycrystals were synthesized via the addition of B4C and Dy2O3. X-ray diffraction confirmed that MgB2 was the predominant phase in all the samples. The superconducting properties of the samples were characterized by in-field temperature-dependent resistivity and magnetization measurements. The upper critical field (Hc2) and the critical current density (Jc) of each sample were estimated. The results indicate significant enhancements in Hc2 and Jc with the optimal addition levels of B4C and Dy2O3. According to collective pinning theory, δl pinning was identified as the dominant pinning type in the fabricated samples. The dominant pinning mechanism was determined to be core surface pinning induced by grain boundaries, which is consistent with predictions made by the Dew–Hughes model.

Influence of trapped magnetic field of Sn-Pb solders on electrical resistivity measurement: an example of superconducting transition of Sn

We examined the effect of the flux-trapped states of Sn60-Pb40 solders on the superconducting properties of a Sn wire. The temperature dependence of electrical resistivity at H = 0 Oe after zero-field cooling (ZFC) showed a sharp superconducting transition at T = 3.7 K. In contrast, field cooling (FC) resulted in a broadening of the transition. The difference between ZFC and FC data evidences the critical effect of trapped fluxes at solders on superconducting states. We propose that, in electrical measurements where magnetic fields of several hundred Oe are critical, field experience should be seriously considered when using solders.

A new aspect of the effect of fluorine doping on structural and superconducting properties in the Bi2Sr1.6La0.4CuO5+δ(O1-xFx) ceramic system

In this study, ceramic samples with the nominal composition Bi2Sr1.6La0.4CuO5+δ(O1-xFx) (where x = 0, 0.2 and 0.4) were synthesized using the solid-state reaction method to investigate the effects of fluorine anionic doping on the Bi-2201 system's structural, microstructural, and superconducting properties. X-ray diffraction analysis (XRD) confirmed the Bi-2201 phase in all samples and total incorporation of fluorine. Doping with fluorine reduced orthorhombicity, leading to an orthorhombic-tetragonal transition. Scanning electron microscopy (EDS) revealed changes in grain shape and size, while energy dispersive x-ray analysis (EDAX) confirmed fluorine incorporation. DC-electrical resistivity measurements showed that fluorine doping decreased the critical transition temperature TC (Onset), with a greater decrease observed at higher fluorine concentrations. The resistivity increase in the normal state of the sample with x = 0.4 was also noted. The conduction mechanism above TC (Onset) = 26.10 K followed the Arrhenius law, indicating thermally activated behavior due to a band gap.

Technology Focus: Offshore Drilling and Completion (October 2024)

The evolution of computational technology, coupled with the ability to digitize hardware and engage with end users, has enabled machine learning to enhance operational efficiency, safety, and cost-effectiveness in offshore oil and gas development. A key takeaway from recent literature is that, while automation tools have been present for years, their widespread adoption has been hindered by a lack of demonstrable financial benefits. To address this, the focus has shifted from mere deployment to achieving real value through significant cost savings, increased safety, and improved operational efficiencies (paper OTC 35137). Automation efforts in onshore operations prioritize efficiency, while offshore automation must focus on risk reduction and minimizing nonproductive time. For instance, a cutting-edge vessel-motion-prediction tool integrates advanced machine-learning techniques with metocean forecasts to enhance the reliability and safety of offshore drilling operations (paper OTC 35341). Paper OTC 35418 presents the importance of autonomous inflow-control devices in maximizing the production life of wells in deepwater West Africa, taking into account the various challenging reservoir conditions. Another critical insight from the research is the role of human intervention in the deployment of automation systems. Successful deployment requires iterative adjustments and feedback from operators to tailor systems to the specific needs of offshore environments. Collaboration among engineers, operators, and decision-makers is essential in refining these technologies to align them with operational goals and safety standards. Overall, these papers underscore the need for strategic adaptation of automation systems to the specific challenges of offshore environments. The success of predictive machine learning in this context depends on its ability to offer measurable financial benefits, improve safety, and drive operational efficiency. Recommended additional reading at OnePetro: www.onepetro.org. SPE 218473 Performance Optimization of Water-Injection Wells Using Autonomous Outflow Control Device Technology in Offshore Norway by G.F. Kvilaas, AkerBP, et al. SPE 218479 Use of Wired Drill Pipe, Along-String Measurements, and Advanced Logging-While-Drilling Imaging Enhances Wellbore-Condition Understanding and Improves Well Delivery Time, While Telemetry-Optimized Ultradeep Resistivity Measurements Enable Precise Geological Well Placement by Stephen Pink, NOV, et al. SPE 218360 Autonomous Restriction Navigation Through Wellbore in Wireline and Slickline Operations by S. DiPasquale, SLB, et al. OTC 35394 Intelligent Optimization of Ultradeepwater Oil-Transmission Risers Using an Enhanced Graph Neural Network by Hong Zhu, China University of Petroleum-Beijing, et al.

Evolution of ferromagnetism and electrical resistivity in Sb-doped Cr4PtGa17

We describe the doping effects on a metallic breathing pyrochlore compound, Cr4PtGa17. Upon doping with Sb, i.e., Cr4Pt(Ga1-xSbx)17, it was found that a selective doping on one of the seven Ga sites occurs. With increasing dopant level, the ferromagnetism in the parent compound is gradually suppressed, along with a decrease in fitted Curie-Weiss temperature (from 61 (1) K to −1.8 (1) K) and effective moment (from ∼2.26 μB/f.u. to ∼0.68 μB/f.u.). Low-temperature heat capacity measurements confirm the absence of magnetic ordering above 0.4 K for the three most doped samples. Meanwhile, electrical resistivity measurements display a metal-semiconductor transition with increasing Sb contents, which is attributed to an increase of Fermi energy based on the calculations of electronic band structure and density of states. Moreover, we have speculated that the ferromagnetism in Cr4PtGa17 is governed by itinerant electrons according to our observations. This study of Sb-doping effect on Cr4PtGa17 provides deeper understanding of magnetism of this system and possibilities for future modifications.

Evaluation of Chemical Resistance of Polymer Mortars Containing Biochar

Partial replacement of quartz flour microfiller in polymer composites with biocarbon is one of the potential ways to utilize this waste. The article discusses the possibility of using biocarbon as a component of vinyl ester mortars, in the context of their chemical resistance. The tests were carried out for mortars with different quantitative compositions, and therefore with different biocarbon contents. They were subjected to 12-month exposure to a chemically aggressive environment. Solutions of 0.5% sulfuric acid(VI) and 5% sodium hydroxide were used. Measures of resistance were changes in weight, compressive strength, longitudinal ultrasonic wave velocities and quantitative changes in microstructure compared to chemically unstressed samples. The results show that vinyl ester mortars with biocarbon are more resistant to chemical aggression with sulfuric(VI) acid solution. A significant decrease in compressive strength, ultrasonic wave velocity and an increase in the values of stereological parameters were observed after exposure of the composites in sodium base solution. This is in contrast to the chemical aggression in the acid solution, after which the changes in the properties and microstructural parameters of the mortars were not so clear

Bowel Inflammation and Nutrient Supplementation: Effects of a Fixed Combination of Probiotics, Vitamins, and Herbal Extracts in an In Vitro Model of Intestinal Epithelial Barrier Dysfunction.

The gut microbiota is a very important factor in the state of health of an individual, its alteration implies a situation of "dysbiosis," which can be connected to functional gastrointestinal disorders and pathological conditions, such as Inflammatory Bowel Disease (IBD), Irritable Bowel Syndrome (IBS), Ulcerative Colitis (UC) and Crohn's Disease (CD), and Colorectal Cancer (CRC). In this work, we studied the effect of a food supplement called ENTERO-AD containing a mix of probiotics (Lactobacillus acidophilus LA1, L. reuteri LR92, Bifidobacterium breve Bbr8), Matricaria Chamomilla, and B group vitamins (B1, B2, B6) on intestinal inflammation. The in vitro model used for the study is the Caco-2 cell, a culture derived from human intestinal adenocarcinoma; the inflammatory condition was achieved with treatment with Lipopolysaccharide (LPS) and the association between Tumor necrosis factor α/Interferon γ (TNF-α/IFN-γ) [1,2]. The effect of ENTERO-AD was evaluated by cell viability, measures of Transepithelial Electrical Resistance (TEER), paracellular permeability, and immunofluorescence. Results of the study have shown that ENTERO-AD has a favorable effect on Caco-2 cells in inflammatory conditions. It improves the integrity of Occludin and Zonula Occludens-1 (ZO-1) proteins, leading to an improvement in terms of TEER values and a reduction of paracellular permeability. This evidence underlines the protective effect of ENTERO-AD and its components in intestinal inflammation.

Bacillus cereus in rice: A review on food poisoning, antimicrobial resistance, and control measures

Bacillus cereus in rice: A review on food poisoning, antimicrobial resistance, and control measures

Correlation between electrical resistivity and compressive strength of stabilized dredged sediment for early quality control

Quality control of stabilized dredged sediment (DS) presents significant challenges due to its high-water content. Nowadays, many in-situ and laboratory tests have been used to evaluate the quality of treated DS, and the dominant method is 28-day unconfined compressive strength that can be done on undisturbed samples from the field and the laboratory. Due to the waiting period to get results from the tests and the destructive nature of tests, it is desirable to use a non-destructive method to control the quality of stabilized DS at an early stage. This study suggests electrical resistivity measurement as a non-destructive and fast method for evaluating the quality of stabilized DS. Dredged sediment samples from Göta älv, Gothenburg, with different water contents, were stabilized with different water-binder ratios at the laboratory. The quality of treated sediments was evaluated by uniaxial compressive strength (UCS) after 28-day of stabilizing, while strength development during the curing period was checked with a free-free resonance test at 7, 14, and 28 days of curing, and the electrical resistivity (ER) measurement monitored on some samples during the curing period. The results indicate that a combination of UCS tests and ER measurements can be utilized early stage evaluation of the quality of stabilized DS already after 24, 48 or 72 h. According to the results, after 24 h of hydration, the electrical resistivity was less than 1 Ωm. After 72 h of hydration, the resistivity was between 1 to 2.5 Ωm, which shows the development of strength. The 28-day strength varied from 0.25 MPa to 2 MPa while the resistivity varied between 3 Ωm to 22 Ωm. The observed variations in resistivity and compressive strength can be attributed to differences in the water-to-binder ratio across the samples.This approach offers a practical, non-destructive method for detecting early quality issues of stabilized DS, enabling quicker decision-making and potentially reducing project timelines and costs while maintaining the integrity and safety of construction projects involving stabilized dredged sediments.

Discovery of a major QTL for resistance to the guava root-knot nematode (Meloidogyne enterolobii) in ‘Tanzania’, an African landrace sweetpotato (Ipomoea batatas)

Sweetpotato, Ipomoea batatas (L.) Lam. (2n = 6x = 90), is among the world’s most important food crops and is North Carolina’s most important vegetable crop. The recent introduction of Meloidogyne enterolobii poses a significant economic threat to North Carolina’s sweetpotato industry and breeding resistance into new varieties has become a high priority for the US sweetpotato industry. Previous studies have shown that ‘Tanzania’, a released African landrace, is resistant to M. enterolobii. We screened the biparental sweetpotato mapping population, ‘Tanzania’ x ‘Beauregard’, for resistance to M. enterolobii by inoculating 246 full-sibs with 10,000 eggs each under greenhouse conditions. ‘Tanzania’, the female parent, was highly resistant, while ‘Beauregard’ was highly susceptible. Our bioassays exhibited strong skewing toward resistance for three measures of resistance: reproductive factor, eggs per gram of root tissue, and root gall severity ratings. A 1:1 segregation for resistance suggested a major gene conferred M. enterolobii resistance. Using a random-effect multiple interval mapping model, we identified a single major QTL, herein designated as qIbMe-4.1, on linkage group 4 that explained 70% of variation in resistance to M. enterolobii. This study provides a new understanding of the genetic basis of M. enterolobii resistance in sweetpotato and represents a major step towards the identification of selectable markers for nematode resistance breeding.

Prediction of physico-mechanical rock characteristics from electrical resistivity tests

The indirect estimation of intact rock properties is particularly useful for preliminary investigations in engineering projects. In this paper we examine the usability of electrical resistivity, a nondestructive measurement, for the prediction of physical and mechanical rock characteristics. Physico-mechanical tests (uniaxial compression, Brazilian tensile, density, and porosity tests) and electrical resistivity measurements were performed on specimens of 36 rock types. Before the resistivity tests, the specimens were completely saturated with saline solution. Evaluation of the test results showed that there are medium or strong correlations between resistivity and rock properties. There are also strong or stronger correlations between the two parameters for the rock classes. The regression equations developed were statistically tested, and their validity was confirmed. The results were also compared with previous studies. The conclusion is that electrical resistivity measurement can be used for reliably estimating physical and mechanical rock characteristics.

Harnessing long-term gridded rainfall data and microtopographic insights to characterise risk from surface water flooding.

Climate projections like UKCP18 predict that the UK will move towards a wetter and warmer climate with a consequent increased risk from surface water flooding (SWF). SWF is typically caused by localized convective rainfall, which is difficult to predict and requires high spatial and temporal resolution observations. The likelihood of SWF is also affected by the microtopographic configuration near buildings and the presence of resilience and resistance measures. To date, most research on SWF has focused on modelling and prediction, but these models have been limited to 2 m resolution for England to avoid excessive computational burdens. The lead time for predicting convective rainfall responsible for SWF can be as little as 30 minutes for a 1 km x 1 km part of the storm. Therefore, it is useful to identify the locations most vulnerable to SWF based on past rainfall data and microtopography to provide better risk management measures for properties. In this study, we present a framework that uses long-term gridded rainfall data to quantify SWF hazard at the 1 km x 1 km pixel level, thereby identifying localized areas vulnerable to SWF. We also use high-resolution photographic (10 cm) and LiDAR (25 cm) DEMs, as well as a property flood resistance and resilience (PFR) database, to quantify SWF exposure at property level. By adopting this methodology, locations and properties vulnerable to SWF can be identified, and appropriate SWF management strategies can be developed, such as installing PFR features for the properties at highest risk from SWF.

Pseudosymmetry in Tetragonal Perovskite SrIrO3 Synthesized under High Pressure.

In this study, we report a tetragonal perovskite structure of SrIrO3 (P4/mmm, a = 3.9362(9) Å, c = 7.880(3) Å) synthesized at 6 GPa and 1400 °C, employing the ambient pressure monoclinic SrIrO3 with distorted 6H structure as a precursor. The crystal structure of tetragonal SrIrO3 was evaluated on the basis of single-crystal and powder X-ray diffraction. A cubic indexing was observed, which was attributed to overlooked superlattice reflections. Weak fractional peaks in the H and K dimensions suggest possible structure modulation by oxygen defects. Magnetization study reveals weak paramagnetic behavior down to 2 K, indicative of the interplay between spin-orbit coupling, electron correlations, and the crystal electric field. Additionally, measurements of electrical resistivity display metallic behavior with an upturn at about 54 K, which is ascribed to weak electron localization and possible structural defects.

A simple Urea approach to N-doped α-Mo2C with enhanced superconductivity

Abstract Chemical doping is a critical factor in the development of new superconductors or optimizing the superconducting transition temperature (T c) of the parent superconducting materials. Herein, a new simple urea approach is developed to synthesize the N-doped α-Mo2C. Benefiting from the simple urea method, a broad superconducting dome is found in the Mo2C1-x N x (0 ≤ x ≤ 0.49) compositions. XRD results show that the structure of α-Mo2C remains unchanged and that there is a variation of lattice parameters with nitrogen doping. Resistivity, magnetic susceptibility, and heat capacity measurement results confirm that the superconducting transition temperature (T c) was strongly increased from 2.68 K (x = 0) to 7.05 K (x = 0.49). First-principles calculations and our analysis indicate that increasing nitrogen doping leads to a rise in the density of states at the Fermi level and doping-induced phonon softening, which enhances electron-phonon coupling. This results in an increase in T c and a sharp rise in the upper critical field. Our findings provide a promising strategy for fabricating transition metal carbonitrides and provide a material platform for further study of the superconductivity of transition metal carbides.