Resistance Measurements Research Articles

Postnatal Cardiometabolic Health After Metformin Use in Gestational Diabetes: A Secondary Analysis of the EMERGE Trial.

Women with GDM display adverse lifetime cardio-metabolic health. We examined whether early metformin in GDM could impact cardio-metabolic risk factors postpartum. EMERGE, a double-blind, placebo-controlled trial randomized pregnancies 1:1 to placebo or metformin at GDM diagnosis and followed participants from randomization until 12±4 weeks postpartum. In total 478 pregnancies were available for postpartum maternal assessment, 237 and 241 assigned to metformin and placebo respectively. Weight (kg), body mass index (BMI) (kg/m2), waist circumference (cm) and blood pressure (mmHg) were measured, infant feeding method documented and bloods drawn for a 75 gram oral glucose tolerance test, fasting insulin, C peptide and lipid analysis. Despite similar weight and BMI at trial randomization, participants receiving metformin had significantly lower weight (79.5±15.9 vs 82.6±16.9kg; p=0.04) and BMI (29.3(5.6) vs 30.5(5.4); p=0.018) at the postpartum visit. However no difference in weight change from randomisation to 12 weeks postpartum was observed between metformin and placebo groups. Overall 29% (n=139) of the cohort met criteria for prediabetes or diabetes, with no positive impact with metformin. There were also no differences in measurements of insulin resistance, blood pressure or lipids between groups. Early metformin use in GDM did not impact important cardio-metabolic parameters in the early postpartum period despite significant benefits in weight gain and insulin use in pregnancy.

Postprandial fatty acid-binding protein4 is associated with muscle insulin resistance.

Fatty acid-binding protein4 (FABP4) has been reported to act as a hepatic insulin resistance factor. We previously reported that fasting FABP4 was correlated with insulin resistance measurements derived from the glucose clamp, and another study reported that postprandial FABP4 levels were decreased in healthy volunteers but were not reported (or known) in participants with type 2 diabetes. We have limited knowledge about the direct effect of FABP4 on muscle cells. We investigated the postprandial FABP4 levels in participants with type 2 diabetes, and the basic mechanism of muscle insulin resistance and FABP4. We performed a meal tolerance test and hyperinsulinaemic-euglycaemic clamp in 22 participants with type 2 diabetes and 26 participants without diabetes. We measured fasting and postprandial serum FABP4. We cultured mouse C2C12 muscle cells, and investigated the effect of FABP4 on glucose uptake. We analysed insulin signalling by western blot and insulin binding assay. The postprandial FABP4 level in participants with type 2 diabetes was higher than that in participants without diabetes. Participants without diabetes had lower postprandial FABP4 than fasting except for one participant, whereas one-third of participants with type 2 diabetes had higher postprandial FABP4 than fasting. Postprandial FABP4 was correlated with the muscle insulin resistance M/I value from a glucose clamp in participants without diabetes (r=-0.42, p<0.05). The increase in FABP4 after a meal correlated with the muscle insulin resistance M/I value (r=-0.44, p<0.05) and the difference between fasting and postprandial glucagon in participants with type 2 diabetes (r=0.36, p<0.05). FABP4 alone appears to increase glucose uptake, and the combination of FABP4 and insulin decreases glucose uptake when compared with insulin alone. FABP4 inhibits insulin signalling of muscle cells through decreases in phosphorylation of insulin receptor substrate1 and Akt. The physiological concentration of FABP4 did not inhibit insulin binding to muscle cells. These results suggested that the postprandial FABP4 level is associated with insulin resistance, and FABP4 may suppress insulin signals.

Electrical Capacitors Based on Silicone Oil and Iron Oxide Microfibers: Effects of the Magnetic Field on the Electrical Susceptance and Conductance.

This paper presents the fabrication and characterization of plane capacitors utilizing magnetodielectric materials composed of magnetizable microfibers dispersed within a silicone oil matrix. The microfibers, with a mean diameter of about 0.94 μm, comprise hematite (α-Fe2O3), maghemite (γ-Fe2O3), and magnetite (Fe3O4). This study investigates the electrical behavior of these capacitors under the influence of an external magnetic field superimposed on a medium-frequency alternating electric field, across four distinct volume concentrations of microfibers. Electrical capacitance and resistance measurements were conducted every second over a 60-s interval, revealing significant dependencies on both the quantity of magnetizable phase and the applied magnetic flux density. Furthermore, the temporal stability of the capacitors' characteristics is demonstrated. The obtained data are analyzed to determine the electrical conductance and susceptance of the capacitors, elucidating their sensitivity to variations in microfiber concentration and magnetic field strength. To provide theoretical insight into the observed phenomena, a model based on dipolar approximations is proposed. This model effectively explains the underlying physical mechanisms governing the electrical properties of the capacitors. These findings offer valuable insights into the design and optimization of magnetodielectric-based capacitors for diverse applications in microelectronics and sensor technologies.

Особливості проведення лабораторної роботи «Вимірювання опору розтіканню струму заземлюючих пристроїв, питомого опору ґрунту, ізоляції мереж та електроустановок» за допомогою віртуального лабораторного стенда

The materials of this scientific article consider the possibility of using a virtual laboratory stand during the laboratory work carried out by students of higher education institutions under the name «Measurement of the resistance to the spread of the current of grounding devices, the specific resistance of the soil, the insulation of networks and electrical installations». This laboratory work is included in the curriculum of the normative educational component «Occupational safety in the industry and civil protection». The article examines the specific advantages of using a virtual stand, in particular its role in improving the quality of the educational process, expanding access to resources, and optimizing educational costs. The purpose of this article is to consider the main possibilities of using the proposed virtual laboratory stand as an innovative approach in the study of complex technical processes and ensuring a high level of training during laboratory work on the topic «Measurement of resistance to the spread of current of grounding devices, soil resistivity, insulation of networks and electrical installations». This laboratory work is a component of the curriculum of the normative educational component aimed at forming in students the ability to identify, analyze and evaluate potential risks associated with the production environment, and which is entitled «Occupational Safety and Civil Protection». Particular attention is paid to the methodology of conducting laboratory work using a virtual stand, including steps for configuring the software, algorithms for performing measurements and analyzing the received data. Methods of simulating various measurement conditions are described in detail, allowing students to practice scenarios that would be difficult or dangerous to implement in real conditions. In the materials of the article, an overview of the interface and functionality of the developed computer program, which reproduces the control components of real laboratory equipment and is intended for the implementation of the functions of a virtual laboratory stand, is reviewed, the key capabilities of the proposed program are described, including the simulation of various laboratory scenarios and the availability of theoretical materials necessary for preparing and conducting a laboratory session, as well as a detailed reproduction of the appearance and control components of real experimental laboratory equipment, which contributes to the creation of a feeling of working with physical devices, the implementation of mathematical models that accurately describe the dependence of output parameters on input parameters. It was also found that the use of similar technologies during other laboratory works from the above-mentioned normative educational component requires further thorough systematic research and publication of their results.

Enzymatic Modulation of the Pulmonary Glycocalyx Enhances Susceptibility to Streptococcus pneumoniae.

The pulmonary epithelial glycocalyx is rich in glycosaminoglycans such as hyaluronan and heparan sulfate. Despite their presence, the importance of these glycosaminoglycans in bacterial lung infections remains elusive. To address this, we intranasally inoculated mice with Streptococcus pneumoniae in the presence or absence of enzymes targeting pulmonary hyaluronan and heparan sulfate, followed by characterization of subsequent disease pathology, pulmonary inflammation, and lung barrier dysfunction. Enzymatic degradation of hyaluronan and heparan sulfate exacerbated pneumonia in mice, as evidenced by increased disease scores and alveolar neutrophil recruitment. However, targeting epithelial hyaluronan in combination with Streptococcus pneumoniae infection further exacerbated systemic disease, indicated by elevated splenic bacterial load and plasma levels of pro-inflammatory cytokines. In contrast, enzymatic cleavage of heparan sulfate resulted in increased bronchoalveolar bacterial burden, lung damage and pulmonary inflammation in mice infected with Streptococcus pneumoniae. Accordingly, heparinase-treated mice also exhibited disrupted lung barrier integrity as evidenced by higher alveolar edema scores and vascular protein leakage into the airways. This finding was corroborated in a human alveolus-on-a-chip platform, confirming that heparinase treatment also disrupts the human lung barrier during Streptococcus pneumoniae infection. Notably, enzymatic pre-treatment with either hyaluronidase or heparinase also rendered human epithelial cells more sensitive to pneumococcal-induced barrier disruption, as determined by transepithelial electrical resistance measurements, consistent with our findings in murine pneumonia. Taken together, these findings demonstrate the importance of intact hyaluronan and heparan sulfate in limiting pneumococci-induced damage, pulmonary inflammation, and epithelial barrier function and integrity.

Portable bioimpedance analyzer for remote body composition monitoring: A clinical investigation under controlled conditions

ObjectivesIn an era when telemedicine is becoming increasingly essential, the development and validation of miniaturized Bioelectrical Impedance Analysis (BIA) devices for accurate and reliable body composition assessment is crucial. This study investigates the BIA Metadieta, a novel miniaturized BIA device, by comparing its performance with that of standard hospital BIA equipment across a diverse demographic. The aim is to enhance remote health monitoring by integrating compact and efficient technology into routine healthcare practices. MethodsA cross-sectional observational study was conducted with 154 participants from the Clinical Nutrition Unit. The study compared resistance (R), reactance (Xc), and phase angle (PhA) measurements obtained from the BIA Metadieta device and a traditional hospital-based BIA device. ResultsAnalysis revealed strong positive correlations between the BIA Metadieta and the hospital-based device for R (r = 0.988, P < 0.001), Xc (r = 0.946, P < 0.001), and PhA (r = 0.929, P < 0.001), indicating the miniaturized device's high accuracy and reliability. These correlations were consistent across different genders and BMI categories, demonstrating the device's versatility. ConclusionsThe BIA Metadieta device, with its miniaturized form factor, represents a significant step forward in the field of remote health monitoring, providing a reliable, accurate, and accessible means for assessing body composition.

Quantitative analysis of interface heat transport at the Si3N4/SiO2 van-der Waals point contact

Si3N4 and SiO2 have been widely used in lithium batteries and optical devices. The high energy density brought by device integration makes the interfacial heat transport at the nano scale a hot spot. To optimize interfacial heat transfer, the roughness of the device surface is continuously reduced down to the nanometer. However, due to the limitation of spatial resolution, it is difficult to realize the measurement of thermal boundary resistance in the case of nanoscale contact by the existing measurement means. There is a great discrepancy between the measurement and simulation results, making the optimization of interfacial heat transfer lack of experimental verification. In this paper, the measurement of thermal boundary resistance of Si3N4/SiO2 interface at the nano-scale, was firstly realized by the optimized 3ω-SThM system. The effect of air tunnel on the heat transfer between real surfaces was also analyzed. The progress made so far provides an effective experimental tool to measure interfacial heat transport at nanoscale point contact.

The pressure field model: a challenge to the conventional Starling and Guyton model of hemodynamic management

IntroductionEnsuring hemodynamic stability with adequate perfusion to vital organs is critical to the safe conduct of anesthesia. Recent advances in hemodynamic monitoring technologies allow pressure, flow, and resistance to be measured continuously; however, there is limited evidence to suggest that these technologies alter clinical management or improve patient outcomes significantly. This may be because the fundamental hemodynamic model, established by Starling and Guyton, fails to offer the granular level of insight needed to guide clinical management.MethodsWe collected hemodynamic data from 950 patients who underwent major surgery with advanced hemodynamic monitoring (AHM) that provided continuously derived cardiac output and vascular resistance measurements. These measurements were based on the hemodynamic model of Starling and Guyton. Additionally, investigational monitoring software was developed to visualize a different hemodynamic model, termed the “pressure field” model. This model expresses the pulsatile, beat-to-beat relationship between ventricular performance (measured by stroke volume) and vascular tone (indicated by systemic elastance).ResultsWithin this dataset were several patients who experienced major hemorrhage. Case studies of these patients demonstrate that abnormal pressure and flow regulation patterns are observed through the lens of the pressure field model, but these patterns are typically not visible through the lens of the traditional Starling and Guyton model (cardiac output and systemic vascular resistance, which involve averaging hemodynamic performance over successive cardiac cycles). Furthermore, “before and after” case studies using our investigational pressure field monitoring software suggest that the traditional Starling and Guyton hemodynamic model has limited utility in managing hemorrhage.DiscussionWe propose that the pressure field model may allow hemorrhage to be managed more effectively via improved monitoring granularity [the beat-by-beat visualization of the stroke volume-systemic elastance relationship, rather than the use of the composite metrics of cardiac output (heart rate × stroke volume) and systemic vascular resistance]. Further research into the utility of the pressure field model is warranted.

CuMn1.7Fe0.3O4 – RE2O3 (RE = Y, Gd) bilayers as protective interconnect coatings for solid oxide cells

Efficient replacement of materials based on critical elements such as cobalt is one of the greatest challenges facing the field of solid oxide cells. New generation materials, free of cobalt show potential to replace conventional materials. However, these materials are characterised by poor ability to block chromium diffusion. This article described the study of CuMn1.7Fe0.3O4 (CMFO) spinel combined with single metal oxide (Y2O3 or Gd2O3) thin films as protective coatings for steel interconnects. CMFO was examined using XRD and TPR. Coated steel samples were oxidised in an air atmosphere at 700 °C for 4000 h. The coatings and oxide scale microstructures and cross-sections were examined by CRI, XRD, and SEM-EDX. The electrical properties of the steel-coating system were evaluated using Area Specific Resistance measurements. Based on the results obtained, it can be concluded that the use of thin layers of rare earth oxides allowed for better blocking of chromium diffusion.

Weyl semimetallic phase in high pressure CrSb2 and structural compression studies of its high pressure polymorphs

In this study, high pressure synchrotron powder X-ray diffraction is used to investigate the compression of two high pressure polymorphs of CrSb2. The first is the CuAl2-type polymorph with an eight-fold coordinated Cr, which can be quenched to ambient conditions from high-pressure high-temperature conditions. The second is the recently discovered MoP2-type polymorph, which is induced by compression at room temperature, with a seven-fold coordinated Cr. Here, the assigned structure is unambiguously confirmed by solving it from single-crystal X-ray diffraction. Furthermore, the electrical properties of the MoP2-type polymorph were investigated theoretically and the resistance calculations under pressure were accompanied by resistance measurements under high pressure on a single crystal of CrSb2. The calculated electronic band structure for the MoP2-type phase is discussed and we show that the polymorph is semimetallic and possesses type-I Weyl points. No further phase transitions were observed for the CuAl2-type structure up to 50 GPa and 40 GPa for the MoP2-type structure. Even though the CuAl2-phase has the highest coordination number of Cr, it was found to be less compressible than the MoP2-phase having a seven-fold coordinated Cr, which was attributed to the longer Cr-Sb distance in the CuAl2-type phase. The discovery of a type-I Weyl semimetallic phase in CrSb2 opens up for discovering other Weyl semimetals in the transition metal di-pnictides under high pressure.

Profiling Novel, Multifunctional Silane-Phosphonate Consolidants for the Mitigation of Gypsum Stone Deterioration via Concerted Autocondensation/Surface Complexation Processes.

Mineral gypsum (selenite) stones have been used extensively by ancient Cretans in the Minoan Palace of Knossos (Crete, Greece), mostly for building and ornamental purposes. Exposure of mineral gypsum to environmental stresses (temperature fluctuations, rain, air-borne pollutants, soluble salts, etc.) causes solubility-driven degradation, and loss of cohesion of the crystal aggregates, with ensuing aesthetic degradation. In this work, the efficiency of four consolidants for artificial gypsum specimens is presented and evaluated based on drilling resistance measurements [drilling resistance measuring system (DRMS)]. Two of them (commercial names RC-70 and RC-90, RC = Rhodorsil Consolidante) are alkoxysilane-based and they are considered as benchmark consolidants. The other two [3-(trihydroxysilyl)propyl methylphosphonate monosodium salt, TRIMEPHONA, and 3-(trihydroxysilyl)propylamino-diphosphonate, TRIPADIPHOS] are multifunctional consolidants because they possess a self-condensable (after hydrolysis) trihydroxysilyl [-Si(OH)3] moiety and phosphonate groups (one in the former, two in the latter). Consolidants RC-70 and RC-90 exhibit rather low consolidation effectiveness. This is not unexpected, as these are alkoxysilane-based and act simply as "fillers" for the pores of the gypsum. Consolidant TRIMEPHONA demonstrates an enhanced level of consolidation action. This is due to its double functionality, i.e., the presence of an anionic phosphorus-based moiety that anchors onto the gypsum surface, and a condensable silane triol [-Si(OH)3] unit. Consolidant TRIPADIPHOS shows excellent gypsum consolidation features and is much more efficient (per unit concentration) than all other tested consolidants. This is assigned to its better gypsum anchoring ability via surface Ca-complexation. Selected compressive strength studies were performed on gypsum samples treated with the phosphorus-based consolidants, and corroborate the findings from DRMS. To shed further light on possible binding modes of the phosphonate moiety on surface Ca2+ sites in gypsum, two model compounds were synthesized and structurally characterized, Ca-C2D and Ca-C3D (C2D = ethylamino-di(methylenephosphonic acid) and C3D = propylamino-di(methylenephosphonic acid).

Multifunctional basalt fiber reinforced polymer composites with in-situ damage self-sensing and temperature-sensitive behavior

In this work, a multifunctional basalt fiber reinforced polymer composite (BFRP) with damage self-sensing and temperature-sensitive behavior was developed. Firstly, carbon nanotubes (CNTs) were deposited on basalt fibers (BF) by electrostatic self-assembly. Then, strong shear forces were applied during melt mixing with polyarylene ether nitrile (PEN) to construct a structure of CNTs surrounding the BF (CSB). This CSB structure endowed the composite with a low percolation threshold (0.82 wt% CNTs), a high conductivity (1.53 × 10−2 S/m at 1.12 wt% CNTs) and enhanced mechanical properties. The combination of resistance and acoustic emission real-time measurements confirmed that the composite achieved an excellent damage self-sensing capability with a maximum gauge factor (GF) of 7.68. Moreover, the composite exhibited a temperature-sensitive behavior with a temperature coefficient of resistance (TCR) of 0.542 %/°C. This study provides a significant guidance for the development of multifunctional BFRP with damage self-sensing and temperature sensitive behavior.

Lifshitz transition enabling superconducting dome around a charge-order critical point.

Superconductivity often emerges as a dome around a quantum critical point (QCP) where long-range order is suppressed to zero temperature, mostly in magnetically ordered materials. However, the emergence of superconductivity at charge-order QCPs remains shrouded in mystery, despite its relevance to high-temperature superconductors and other exotic phases of matter. Here, we present resistance measurements proving that a dome of superconductivity surrounds the putative charge-density-wave QCP in pristine samples of titanium diselenide tuned with hydrostatic pressure. In addition, our quantum oscillation measurements combined with electronic structure calculations show that superconductivity sets in precisely when large electron and hole pockets suddenly appear through an abrupt change of the Fermi surface topology, also known as a Lifshitz transition. Combined with the known repulsive interaction, this suggests that unconventional s± superconductivity is mediated by charge-density-wave fluctuations in titanium diselenide. These results highlight the importance of the electronic ground state and charge fluctuations in enabling unconventional superconductivity.

Magnetic vortex polarity reversal induced gyrotropic motion spectrum splitting in a ferromagnetic disk

We investigate the gyrotropic motion of the magnetic vortex core in a chain of a few micron-sized Permalloy disks by electrical resistance measurement with amplitude-modulated magnetic field. We observe a distinctive splitting of the resistance peak due to the resonant vortex-core motion under heightened radio frequency (RF) magnetic field excitation. Our micromagnetic simulation identifies the splitting of the resonant peak as an outcome of vortex polarity reversal under substantial RF amplitudes. This study enhances our understanding of nonlinear magnetic vortex dynamics amidst large RF amplitudes and proposes a potential pathway for spintronic neural computing thanks to their unique and controllable magnetization dynamics.

Simultaneous determination of the phase boundary thermal resistance and thermal conductivity in phase-separated TiO2 thin films

Phase boundaries, most often between crystalline and amorphous phases of a material, are ubiquitous lattice imperfections in thin films, particularly deposited by low temperature processes such as atomic layer deposition (ALD). Thermal resistances from these boundaries may impede phonon transport and reduce thermal conductivity. However, to date, there have been no reports on the direct measurement of the phase boundary thermal resistance, due in part to challenges associated with fabricating an atomically flat yet geometrically planar interface between different phases within a film. Here, we present a systematic study to simultaneously determine the phase boundary thermal resistance and thermal conductivity in a series of phase-separated titanium oxide (TiO2) thin films prepared via plasma-enhanced ALD (PEALD). A precise implementation of per-cycle plasma treatment enables extremely localized crystallization—i.e., plasma-assisted atomic layer annealing (ALA)—and the fabrication of crystalline/amorphous layered structures with their respective thicknesses systematically varied. Frequency-domain thermoreflectance measures the effective thermal conductivity of each film and its top and bottom interfaces, confirmed independently using time-domain thermoreflectance. We simultaneously solve a system of linear equations generated by applying a series resistor model to each film, yielding the phase boundary thermal resistance of 5.1 m2 K GW–1 between crystalline and amorphous TiO2, as well as the thermal conductivities of 5.1 and 2.1 W m–1 K–1 for crystalline and amorphous TiO2, respectively. The results suggest that the crystalline/amorphous phase boundary acts like a layer of crystalline (amorphous) TiO2 with equivalent thickness ∼26 (∼11) nm.

Revitalizing gut barrier integrity: role of miR-192-5p in enhancing autophagy via Rictor in enteritis.

Intestinal inflammation and compromised barrier function are critical factors in the pathogenesis of gastrointestinal disorders. This study aimed to investigate the role of miR-192-5p in modulating intestinal epithelial barrier (IEB) integrity and its association with autophagy. A DSS-induced colitis model was used to assess the effects of miR-192-5p on intestinal inflammation. In vitro experiments involved cell culture and transient transfection techniques. Various assays, including dual-luciferase reporter gene assays, quantitative real-time PCR, Western blotting, and measurements of transepithelial electrical resistance, were performed to evaluate changes in miR-192-5p expression, Rictor levels, and autophagy flux. Immunofluorescence staining, H&E staining, TEER measurements, and FITC-dextran analysis were also used. Our findings revealed a reduced expression of miR-192-5p in inflamed intestinal tissues, correlating with impaired IEB function. Overexpression of miR-192-5p alleviated TNF-induced IEB dysfunction by targeting Rictor, resulting in enhanced autophagy flux in enterocytes (ECs). Moreover, the therapeutic potential of miR-192-5p was substantiated in colitis mice, wherein increased miR-192-5p expression ameliorated intestinal inflammatory injury by enhancing autophagy flux in ECs through the modulation of Rictor. Our study highlights the therapeutic potential of miR-192-5p in enteritis by demonstrating its role in regulating autophagy and preserving IEB function. Targeting the miR-192-5p/Rictor axis is a promising approach for mitigating gut inflammatory injury and improving barrier integrity in patients with enteritis.NEW & NOTEWORTHY We uncover the pivotal role of miR-192-5p in fortifying intestinal barriers amidst inflammation. Reduced miR-192-5p levels correlated with compromised gut integrity during inflammation. Notably, boosting miR-192-5p reversed gut damage by enhancing autophagy via suppressing Rictor, offering a potential therapeutic strategy for fortifying the intestinal barrier and alleviating inflammation in patients with enteritis.

Electric field control of the energy gap in ZnO and BaSnO3 films grown on PMN-PT

ZnO and BaSnO3 (BSO) thin films grown on Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) substrates have been studied using electrical resistance and photoconductivity (PC) spectra measurements under different applied electric fields on the substrate. The behavior of the resistance and the energy gap (EG) extracted from the PC spectra are modified by the polarization state of the substrate in the case of the ZnO film, while for BSO, these physical parameters depend on the strain imposed by the substrate when a voltage is applied on the PMN-PT. In the latter case, an in-plane tensile (compressive) strain leads to a reduction (increase) in the resistance and the energy gap when an external electric field is applied on the substrate. The behavior of ZnO and BSO can be explained by the different crystalline structure in both films and by the fact that ZnO is also a piezoelectric material. In ZnO, a change in the polarization state of the substrate is associated with an imposed strain and an induced polarization on the film that leads to a modification of the band bending and hence of the energy gap. In the case of BSO, a shift of the impurity and conduction band generates a modification of the energy gap for the different types of strain.

Vitamin B9 as a new eco-friendly corrosion inhibitor for copper in 3.5% NaCl solution

Folic acid salt (sodium folate) has been studied as an eco-friendly and non-toxic copper corrosion inhibitor in 3.5 % NaCl solution. Electrochemical impedance spectroscopy, polarization resistance, and weight-loss measurements show that the inhibitor efficiency increases with the concentration increase (the highest value- 96 % was reported for 16 mM sodium folate solution after 24 h). EIS data indicate that sodium folate is a barrier inhibitor. The standard Gibbs free energy of adsorption obtained using the Langmuir model (–27.5 kJ/mol) suggests that both chemisorption and physisorption may occur. The decrease in the inhibitor efficiency with temperature increase (the temperature coefficient of corrosion inhibition is –0.0045 1/oC) shows that the physical interactions between the inhibitor and metal surface dominate in the studied system. Potential chemical changes in the sodium folate solution were investigated using UV–VIS spectroscopy. Furthermore, the copper surface after immersion in the presence and absence of inhibitor was characterized with scanning electron microscopy, energy-dispersive X-Ray spectroscopy, and microscopic photographs. The protection of copper elements using sodium folate was found to be a promising method that is worth further development.

Leaf membrane leakage and xylem hydraulic failure define the point of no return in drought-induced tree mortality in Cupressus sempervirens.

Measurements of resistance to embolism suggest that Cupressus sempervirens has a stem xylem that resists embolism at very negative water potentials, with 50% embolism (P50) at water potentials of approximately -10 MPa. However, field observations in a semi-arid region suggest tree mortality occurs before 10% embolism. To explore the interplay between embolism and plant mortality, we conducted a controlled drought experiment involving two types of CS seedlings: a local seed source (S-type) and a drought-resistant clone propagated from a semi-arid forest (C-type). We measured resistance to embolism, leaf relative water content (RWC), water potential, photosynthesis, electrolyte leakage (EL), plant water loss, leaf hydraulic conductivity, and leaf non-structural carbohydrate (NSC) content during plant dehydration and before rewatering. All measured individuals were monitored for survival or mortality. While the S- and C-types differed in P50, transpiration, and mortality rates, both displayed seedling mortality corresponding to threshold values of 52-55% leaf RWC, 55% and 18.5% percent loss of conductivity (PLC) in the xylem, which corresponds to 48% and 37% average EL values for S and C types, respectively. Although C-type C. sempervirens NSC content increased in response to drought, no differences were observed in NSC content between live and dead seedlings of both types. Our findings do not fully explain tree mortality in the field but they do indicate that loss of membrane integrity occurs before or at xylem water potential, leading to hydraulic failure.

Chromium-Free Coating for Al Alloy Corrosion Protection Based on a Novel Ti/Mg Oxyfluoride

Chromium-free corrosion protection of aluminum alloys comparable to that of chromates (Cr(VI)) is demonstrated using a TiF6 2− fluoro-anion-based coating recipe containing boric acid and a Mg salt. Boric acid drove TiF6 2− hydrolysis enabling up to micrometer-scale thick coatings. The Mg salt led to deposition of a novel crystalline phase Ti/Mg oxyfluoride coating with an approximate composition of Ti5MgO7F8. Corrosion protection performance was characterized by polarization resistance measurements during immersion in 5% aqueous NaCl solution and neutral salt fog exposure following ASTM B.117. The performance is discussed in terms of the presence of fluoride in the coating enabling active behavior during its gradual depletion (in corrosion environments) toward a final composition approaching TiO2. This active corrosion protection mechanism may be more generally applicable for transition metal-based coatings that do not have high oxidation state oxo-anions, but do have stable fluoro-anions.