Irreversible Degradation Research Articles

Radical-Mediated Degradation of Thiol-Maleimide Hydrogels.

Michael addition between thiol- and maleimide-functionalized molecules is a long-standing approach used for bioconjugation, hydrogel crosslinking, and the functionalization of other advanced materials. While the simplicity of this chemistry enables facile synthesis of hydrogels, network degradation is also desirable in many instances. Here, the susceptibility of thiol-maleimide bonds to radical-mediated degradation is reported. Irreversible degradation in crosslinked materials is demonstrated using photoinitiated and chemically initiated radicals in hydrogels and linear polymers. The extent of degradation is shown to be dependent on initiator concentration. Using a model linear polymer system, the radical-mediated mechanism of degradation is elucidated, in which the thiosuccinimide crosslink is converted to a succinimide and a new thioether formed with an initiator fragment. Using laser stereolithography, high-fidelity spatiotemporal control over degradation in crosslinked gels is demonstrated. Ultimately, this work establishes a platform for controllable, radical-mediated degradation in thiol-maleimide hydrogels, further expanding their versatility as functional materials.

High‐Entropy Phase Stabilization Engineering Enables High‐Performance Layered Cathode for Sodium‐Ion Batteries

AbstractO3‐type layered oxides are considered as one of the most promising cathode materials for rechargeable sodium‐ion batteries (SIBs) due to their appealing energy density and feasible synthesis. Nevertheless, it undergoes complicated phase transitions and pronounced structural degradation during the cycling of charge/discharge process, rendering severe volumetric strain and poor cycling performance. Herein, a zero‐strain high‐entropy NaNi0.2Fe0.2Mn0.35Cu0.05Zn0.1Sn0.1O2 cathode for SIBs is presented by high‐entropy phase stabilization engineering. It is verified that this low‐nickel cobalt‐free high‐entropy cathode can deliver a highly reversible phase evolution, zero volumetric strain, and a significantly improved cycling performance in full cells (87% capacity retention after 500 cycles at 3.0 C). Combining X‐ray absorption spectra and first‐principles calculations, the varied elemental functions in the high‐entropy framework are clearly elucidated, namely, Ni/Fe/Cu acts as charge compensators, while Mn/Zn/Sn serve as interlayer slipping inhibitors through enhanced charge localization besides their stable valence states. By addressing the volumetric strain and cycling instability concerns for O3‐type cathode materials, this work presents a promising strategy for inhibiting irreversible phase transitions and structural degradation in intercalation electrodes, which significantly boosts the development of commercially feasible cathodes for high‐performance SIBs.

Micromechanical modelling on the elastoplastic damage and irreversible critical current degradation of the twisted multi-filamentary Nb3Sn superconducting strand

Micromechanical modelling on the elastoplastic damage and irreversible critical current degradation of the twisted multi-filamentary Nb3Sn superconducting strand

Effect of Docetaxel on Matrix Metalloproteinase 1 Expression in Freund’s Adjuvant Induced Arthritis

Rheumatoid arthritis is an autoimmune disorder that affects the synovial joints. It lead to inflammatory changes occur in synovial tissue, cartilage, bone, and, less frequently, extra-articular structures. Docetaxel, is an anti-neoplastic drug. Methotrexate is a treatment for early-stage rheumatoid arthritis but have 30% failure in treatment within the first year due to resistance or side effects. Matrix metalloproteinase 1 is the proteinase primarily in charge of the irreversible degradation of cartilage, bone, and tendons in the joints, which are induced by cytokines. This study aims to evaluate the effects of docetaxel and methotrexate on Matrix metalloproteinase 1 in the structure of the induced arthritis joints. Methods: To induce the disease, complete Freund's adjuvant is injected subcutaneously into rats. From the 40 male Wister rats, five groups of eight were formed. The control group is composed of non-diseased rats. The second group is induced by complete Freund's adjuvant and 0.5 ml of normal saline was administered intraperitoneally to both the control and induction groups. After being induced by complete Freund's adjuvant, the third group is administered 1 mg/kg/ on alternate day of Docetaxel based on a preliminary experiment. The fourth group is induced and given 1 mg/kg/week of Methotrexate intraperitoneally. The fifth group receives a half dose of Methotrexate and Docetaxel simultaneously. Serum level of Anti Cyclical citrullinated Peptide Antibody, tissue homogenate level of tumor necrosis factor-alpha, knee joint circumference and Immunohistochemical of Matrix metalloproteinase 1 measurements were applied. Results: Significant decreased in the Serum level of Anti-Cyclic citrullinated Peptide Antibody, tissue homogenate level of tumor necrosis factor-alpha & Knee joint circumference in the Docetaxel group. significant lowering in the expression of Matrix metalloproteinase 1 immunoreactivities in Docetaxel and Methotrexate groups with almost absent spots of positive reaction with the matrix of synovial tissue, hyaline cartilage & articular surface. Conclusion: This study showed that Docetaxel may have anti-arthritic effect through their significant lowering expression of Matrix metalloproteinase 1 immunoreactivities.
 

Experimental research on the influence of HTS tape width and former type on the transverse compression performance of CORC cables

The huge transverse Lorentz force experienced by CORC cable during the operation of fusion projects may cause irreversible degradation of its current-carrying capacity. Therefore, it is particularly important to study the influence of cable parameters on their transverse compression performance, and use these influence laws to adjust cable parameters to improve the critical value of transverse compression load that CORC cables can withstand. Solid copper bar former CORC cables with a former diameter of 5.57 mm are produced using HTS (high temperature superconducting) tapes (manufactured by Shanghai Superconductor) of 4 mm and 5 mm width respectively. The experimental results show that the CORC cable wound with 5 mm wide HTS tape has a greater critical transverse compression load than the cable wound with 4 mm wide HTS tape. This indicates that using wider HTS tapes to wind CORC cables can effectively improve their transverse compression performance. A solid copper bar former CORC cable and a stainless steel spiral tube former CORC cable are also produced. Through transverse compression experiments, it is found that the critical transverse compression load of the solid copper bar former and the stainless steel spiral tube former CORC cable are 130 kN/m and 89 kN/m, respectively. This indicates that the solid copper bar former CORC cable has better transverse compression performance. In addition, we also compared the influences of flat and arc pressure blocks on the transverse compression performance of CORC cables, and this experimental results provided a basis for the selection of the bobbin structure when using CORC cables to make coils.

Multi-scaled temporal modeling of cardiovascular disease progression: An illustration of proximal arteries in pulmonary hypertension

The progression of cardiovascular disease is intricately influenced by a complex interplay between physiological pathways, biochemical processes, and physical mechanisms. This study aimed to develop an in-silico physics-based approach to comprehensively model the multifaceted vascular pathophysiological adaptations. This approach focused on capturing the progression of proximal pulmonary arterial hypertension, which is significantly associated with the irreversible degradation of arterial walls and compensatory stress-induced growth and remodeling. This study incorporated critical characteristics related to the distinct time scales for the deformation, thus reflecting the impact of mean pressure on artery growth and tissue damage. The in-silico simulation of the progression of pulmonary hypertension was realized based on computational code combined with the finite element method (FEM) for the simulation of disease progression. The parametric studies further explored the consequences of these irreversible processes. This computational modeling approach may advance our understanding of pulmonary hypertension and its progression.

Assessment of captan pesticide stability by thermal and spectroelectrochemical analysis

In this study, thermal analysis and electrochemical methods were used to evaluate the stability of captan pesticide (CPTN). Simultaneous Thermogravimetry (TG), Differential Thermal Analysis (DTA) and Differential Scanning Calorimetry (DSC) were successfully applied to study the stability of CPTN in the temperature range from 20 to 600 °C. The stability evaluation of CPTN by spectroelectrochemical analysis was carried out using cyclic voltammetry (CV) and electrolysis at constant current density in association with UV−Vis spectrophotometry. Thermoanalytical results revealed a relative stability of CPTN up to a temperature of 154 °C, and above this temperature the pesticide molecule undergoes irreversible degradation. The kinetic approach of the electrochemical results on the electrochemical degradation of CPTN showed a rate constant of 0.02 min−1 in the presence of chloride ions and 0.089 min−1 in the presence of bromide ions. Thermal and electrochemical methods are considered effective strategies applied in order to eliminate pesticides from polluted waters, and the choice of optimal parameters can considerably increase the efficiency of decontamination. The study also aims to provide insights into electrode processes to address the mechanism of electrochemical degradation.

Effect of startup modes on cold start performance of PEM fuel cells with different cathode flow fields

Proton Exchange Membrane Fuel Cell (PEMFC) is widely recognized for its cleanliness and high efficiency, but is still facing challenges in cold environments. At low temperatures, the formation of ice and repeated freezing/thawing cycles may cause cell performance reduction and irreversible degradation. The cathode flow field of PEMFCs has a significant effect on the performance. In contrast to the conventional “channel-ridge” flow field, the metal foam has the advantages of excellent pre-distribution of gases and water drainage, which make it a promising candidate for the cold start. This paper examines the cold start of PEMFCs with metal foam flow field (MFFF) and serpentine flow field (SFF), and the influence of constant current mode, constant voltage mode, and ramping current mode is investigated experimentally through performance test and electrochemical characterization. The results show that lowering the voltage and increasing the current can enhance the cold-start performance of fuel cells. The MFFF fuel cell has superior cold start performance compared to the SFF fuel cell under the constant voltage mode of 0.3 V. Furthermore, the variable current mode is developed by considering the distinct properties of heat and water production during various phases, and the results indicate that increasing the current density at the unsaturated stage leads to an elevated rate of heat production and a reduced rate of water production, which can improve the cold start of PEMFCs.

In situ electrochemical regeneration of nanogap hotspots for continuously reusable ultrathin SERS sensors

Surface-enhanced Raman spectroscopy (SERS) harnesses the confinement of light into metallic nanoscale hotspots to achieve highly sensitive label-free molecular detection that can be applied for a broad range of sensing applications. However, challenges related to irreversible analyte binding, substrate reproducibility, fouling, and degradation hinder its widespread adoption. Here we show how in-situ electrochemical regeneration can rapidly and precisely reform the nanogap hotspots to enable the continuous reuse of gold nanoparticle monolayers for SERS. Applying an oxidising potential of +1.5 V (vs Ag/AgCl) for 10 s strips a broad range of adsorbates from the nanogaps and forms a metastable oxide layer of few-monolayer thickness. Subsequent application of a reducing potential of −0.80 V for 5 s in the presence of a nanogap-stabilising molecular scaffold, cucurbit[5]uril, reproducibly regenerates the optimal plasmonic properties with SERS enhancement factors ≈106. The regeneration of the nanogap hotspots allows these SERS substrates to be reused over multiple cycles, demonstrating ≈5% relative standard deviation over at least 30 cycles of analyte detection and regeneration. Such continuous and reliable SERS-based flow analysis accesses diverse applications from environmental monitoring to medical diagnostics.

Polaronic Stabilities of Exciton Sensitizers Govern Operational Lifetime of Thermally Activated Delayed Fluorescence Assisted Fluorescence Organic Light‐Emitting Devices

AbstractThermally activated delayed fluorescence (TADF) assisted fluorescence organic light‐emitting devices (TAF‐OLEDs), also known as hyperfluorescence OLEDs, sometimes have limited operational lifetimes, making them unsuitable for industrial applications. Although, this limitation is believed to originate from the irreversible degradation of constituent materials, the chemical processes underlying this degradation remain elusive. This study enables to better understand the chemical origins of the degradation processes by identifying key degradation intermediates in emission layers comprising 2,8‐di‐tert‐butyl‐5,11‐bis(4‐tert‐butylphenyl)‐6,12‐diphenyltetracene (TBRb) as the fluorescent emitter and 1,4‐azaborin‐based molecules exhibiting multi‐resonance (MR) TADF behaviors, 5,9‐diphenyl‐5,9‐diaza‐13b‐boranaphtho[3,2,1‐de]anthracene (DABNA‐1) and 9‐([1,1′‐biphenyl]‐3‐yl)‐N,N,5,11‐tetraphenyl‐5,9‐dihydro‐5,9‐diaza‐13b‐boranaphtho[3,2,1‐de]anthracen‐3‐amine (DABNA‐2), as exciton sensitizers. Despite the sensitizers facilitating energy transfer to TBRb, they also reduce the device's longevity. While the singlet and triplet excitons of TBRb, as well as excitons of the sensitizers, prove to be relatively stable, the radical ions of the sensitizers prove to be the key limit to device longevity. Comparisons with donor–acceptor‐type TADF exciton sensitizers, 2,4,5,6‐tetrakis(9H‐carbazol‐9‐yl)benzene‐1,3‐dicarbonitrile (4CzIPN), 10,10′‐(sulfonyldi‐4,1‐phenylene)bis[9,10‐dihydro‐9,9‐dimethylacridine] (DMAC‐DPS), and 10‐[4‐(4,6‐diphenyl‐1,3,5‐triazin‐2‐yl)phenyl]‐9,10‐dihydro‐9,9‐dimethylacridine (DMAC‐TRZ), corroborate the findings, pointing to radical ions as primary degradation intermediates. This knowledge is essential for enhancing the durability of TAF‐OLEDs in future designs.

Green Criminology in the Niger Delta of Nigeria: Why African Women’s Voices Matter

Oil spills in resource-rich areas in Africa have led to irreversible environmental degradation, resulting in social conflicts that have greatly affected women. Yet, the experiences of ordinary women affected by resource extraction activities in the Global South are often marginalised. Recent calls for the southernising of criminology are gaining momentum and could be linked to calls for rethinking how knowledge about Africa is produced, including in its gendered dimensions. For example, in what ways do women’s voices matter on issues related to the environment in the Niger Delta? And how do their voices intersect with green criminological theories? This article focuses on amplifying affected women’s lived experiences in the resource-rich area of the Niger Delta of Nigeria. Using data collected between 2019 and 2022 through participatory video, focus group discussions, and in-depth interviews, the paper underscores the need to give women a voice on matters that affect the environment, and peace and war dynamics.

Charting the Irreversible Degradation Modes of Low Bandgap Pb‐Sn Perovskite Compositions for De‐Risking Practical Industrial Development

AbstractThe commercialization of a solar technology necessitates the fulfillment of specific requirements both regarding efficiency and stability to enter and gain space in the photovoltaic market. These aims are heavily dependent on the selection of suitable materials, which is critical for suppressing any reliability risks arising from inherent instabilities. Focusing on the absorber material, herein the most suitable low bandgap lead‐tin composition candidate for all‐perovskite tandem applications is investigated by studying their degradation mechanisms with both widely available and advanced characterization techniques. Three irreversible degradation processes are identified in narrow bandgap Pb‐Sn perovskite absorbers: 1) Tin (Sn) oxidation upon air exposure, 2) methylammonium (MA) loss upon heat exposure, and 3) formamidinium (FA) and cesium (Cs) segregation leading to impurity phase formation. From an industrial perspective, it is proposed to refocus attention on FASn0.5Pb0.5I3 which minimizes all three effects while maintaining a suitable bandgap for a bottom cell and good performance. Moreover, a practical and highly sensitive characterization method is proposed to monitor the oxidation, which can be deployed both in laboratory and industrial environments and provide useful information for the technological development process, including, the effectiveness of encapsulation methods, and the acceptable time windows for air exposure.

Spectrally Stable Deep-Blue Light-Emitting Diodes Based on Layer-Transferred Single-Crystalline Ruddlesden-Popper Halide Perovskites.

A novel approach to producing high-color-purity blue-light-emitting diodes based on single-crystalline Ruddlesden-Popper perovskites (RPPs) is reported. The utilization of a pure bromide composition eliminates any possibility of halide segregation, which can otherwise lead to undesired shifts in the emission wavelength or irreversible degradation of the spectral line width. Phase-pure PEA2MAPb2Br7 single crystals with a lateral size exceeding 1 cm2 can be synthesized using the inverse temperature crystallization method. To prepare RPP layers with a thickness of less than 50 nm, we employ a thinning process of the initially thick bulk crystals, followed by a dry-transfer process to place them onto a hole transport layer and an indium-tin-oxide-coated glass substrate. By utilizing polydimethylsiloxane as a handling layer, deformations of the bulk RPP crystal and exfoliated RPP layer, as well as the formation of defects such as pinholes, can be effectively suppressed. Subsequent depositions of an electron transport layer and a metal contact complete the fabrication of electroluminescence (EL) devices. The EL devices utilizing the single-crystalline RPP demonstrate excellent spectral stability across a broad range of the applied bias voltage spanning from 4.5 to 10 V, exhibiting a significantly narrow line width of 14 nm at an emission wavelength of 440 nm that can potentially cover 99.3% of the Rec. 2020 color gamut. The sharp EL emission spectrum can be effectively preserved, avoiding any broadening of the line width, by suppressing Joule heating throughout the device operation, in addition to the intrinsic stability of single-crystalline RPPs.

Assessment of the Erosion and Outflow Intensity in the Rif Region under Different Land Use and Land Cover Scenarios

The port of Tangier Med is essential due to its strategic location, as it is an important trading center linking Europe, North America, and Africa. However, the increased rates of downstream sediment transportation put pressure on the sustainable future of the port. Thus, assessing the existing erosion rates and future improvement scenarios is imperative for planning sustainable management at the catchment level. We utilize the Erosion Potential Model (EPM) combined with the Intensity of Erosion and Outflow (IntErO) algorithm to assess the erosion and outflow intensity and to distinguish the sediment-producing areas in the R’mel watershed. The port’s proximity at the bottom of the slope opposite the R’mel Dam is relevant in this context. Initial results show an average erosion rate of 13 t/ha/year. Quarry operations were identified as the primary sediment source, as indicated by the factors contributing to erosion. The qualitative PAP/RAC (Priority Actions Program/Regional Activity Center) model was used to assess the development trends in the watershed, confirming a clear tendency toward irreversible degradation in the quarry areas. Considering that the mined carbonate lithology represents 23.77% of the total area of the catchment, the situation in the region could deteriorate if quarry operations continue. The simulation of quarry rehabilitation scenarios through land use and land cover change (LULC) with IntErO shows that reforestation of quarries can significantly reduce erosion rates (4.78 t/ha/year) compared to their conversion to agricultural land. This study underlines the effectiveness of IntErO, based on the EPM model, in quickly and effectively mapping and quantifying water erosion.

Effect of transverse compressive stress applied at room temperature on Nb3Sn Rutherford cables

The accelerator magnets for the high luminosity upgrade of the large Hadron collider use Nb3Sn conductor to achieve the required in-field performance. To sustain the Lorentz forces during operation, a pre-compression is applied to the coils during the fabrication of the magnet. This can lead to an irreversible degradation of the Nb3Sn conductor due to its mechanical sensitivity. In this study, the impact of the pre-compression applied to the conductor at room temperature is investigated using a reacted double-stack specimen made of two Nb3Sn Rutherford cables. The cables have a keystone angle and are stack with a non-inverted configuration, without compensating the angle. The rectangular specimen is submitted to increasing transverse compressive stresses at room temperature applied perpendicularly to its width. The non-inverted configuration and the rectangular shape of the total specimen can thus lead to stress concentration. The pressure applied covers the range from 130 MPa to 190 MPa with a 10 MPa step increase. After each cumulated stress level, transport current measurements are performed in liquid helium and in background fields of up to 9.6 T in the FReSCa test station at CERN Metallographic analyses of several samples are made at selected stress levels. Monotonic and cumulated stresses are applied and the impact of mechanical cycling is analyzed. Procedures are specifically developed to minimize surface damage during samples’ preparation. The observations are compared with the electrical measurements in order to correlate the irreversible effect of the transverse pressure with the A15 damage state in the cross section. The transport current measurements of the double-stack specimen show degradation of critical current and n-value starting at respectively 170 MPa and 160 MPa cumulated loadings. However, cracks in the A15 phase are already observed in a metallographic sample subjected to 140 MPa.

Abstract A005: Enhanced DNA damage and disruption of repair by iodinated thymidine analogues with Tipiracil for clinical radiation sensitization

Abstract IUdR incorporation into cellular DNA enhances radiation induced DNA damage and impairs repair pathways. IUdR has been explored as a clinical radiation sensitizer in Phase I and II clinical trials of sarcomas and gliomas, showing clinical activity. A major barrier to acceptance of this therapy has been the poor pharmacokinetic (PK) profile of IUdR which has a blood plasma half-life of less than 10 minutes. Continuous IV infusion of IUdR has been used to achieve clinically relevant DNA incorporation into tumor cells, but technical limitations of delivery and acute toxicities in rapidly proliferating normal tissues presented barriers to advancing this approach. To improve the PK profile of IUdR, a prodrug strategy has been employed leading to the development of ropidoxuridine (IPdR), which improved the PK profile, demonstrated oral bioavailability of the active metabolite IUdR, showed less normal tissue toxicity, and provided tumor radiation sensitization. IPdR plus XRT has been tested in Phase 0 and Phase 1 clinical trials and a phase II trial is proposed for glioblastoma treatment. We report here a second approach to improve the PK profile of orally administered IUdR by combining these iodinated thymidine analogs with the metabolism inhibitor, Tipiracil (TPI) which inhibits thymidine phosphorylase, the primary enzyme responsible for irreversible IUdR degradation, and is currently used in the FDA approved combination drug Lonsurf. Oral co-administration of IUdR and TPI in rats dramatically improved the PK profile of IUdR, increasing the half-life of the compound to 1.5 hours and boosting the maximum plasma concentration by approximately 8-fold. We studied the effects of Tipiracil on the metabolism of IUdR by varying the molecular ratio of IUdR/TPI from 2:1 up to a ratio of 10:1 and discovered that the plasma concentration of IUdR plateaued between a ratio of 5:1 and 10:1. This new combination therapy of IUdR/TPI yields a PK profile of IUdR that is relevant to clinical treatment in combination with RT and offers to expand potential clinical radiation sensitizer applications. Citation Format: Scott Grindrod, Alfredo Velana, Tyvin Rich, Mira Jung, Dalong Pang, Anatoly Dritschilo. Enhanced DNA damage and disruption of repair by iodinated thymidine analogues with Tipiracil for clinical radiation sensitization [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: DNA Damage Repair: From Basic Science to Future Clinical Application; 2024 Jan 9-11; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2024;84(1 Suppl):Abstract nr A005.

Assessing decarbonization: a comparison of the green sacrifice ratio for China and India

ABSTRACT Carbon mitigation and net-zero targets have an important place on the political agenda for all countries. Countries have been seeking to decouple economic growth and carbon emissions to achieve decarbonization. However, there is a cost of the decarbonization of economies, which can be called as Green Sacrifice Ratio (GSR), and this is critical for developing countries because they have been in the growing stage. By considering the critical role of GSR in achieving net-zero emissions by decarbonizing economies, the study comparatively examines how much environmental quality should be sacrificed for per capita economic growth in China and India. In line with this purpose, the study uses the Fourier-Shin cointegration test and various time series estimators with Fourier approximations for the period from 1989/Q1 to 2022/Q4. Estimation results are as follows: (i) all variables follow the non-stationary process, (ii) the long-run relationship exists between variables, and (iii) Estimation results show that GSR is 0.65% for China and 0.78% for India. Therefore, China and India sacrifice a significant amount of environmental quality for a 1% increase in per capita income level. Also, the ecological cost of increasing economic welfare in India is higher with regard to China. Besides, the results are robust according to the alternative method. Thus, the study recommends that both Chinese and Indian policymakers should revise the economic expansion structure with green growth strategies to prevent irreversible environmental degradation due to higher economic growth.

CO2/Cr-tolerance and oxygen reduction reaction of novel high-entropy perovskite cathode for intermediate temperature solid oxide fuel cell

The development and exploration of cathode oxides with outstanding electrocatalytic activity are critical processes aimed at achieving a decrease in the operation temperature of solid oxide fuel cells (SOFC). Herein, a novel high-entropy oxide, La0.2Pr0.2Nd0.2Sm0.2Gd0.2BaCoFeO5+δ (HEP), which incorporates five lanthanide species (La, Pr, Nd, Sm, and Gd) in the A-site of perovskite, has been specifically developed and assessed as selected cathode for intermediate-temperature SOFC. Investigations of phase structure, chemical compatibility, oxygen transport characteristics, oxygen reaction kinetic, thermal expansion, surface chemical state, conductivity, as well as CO2/Cr-durability are thoroughly performed to assess the basic physicochemical properties of the HEP cathodes. The HEP cathode possesses good operational stability, moderate thermal expansion behavior, fast oxygen transport dynamics, and superior chemical compatibility with the electrolyte. At 700 °C, the polarization resistance low to 0.072 Ω cm2 and output power density high to 332.2 mW cm−2 were obtained for the symmetrical and electrolyte-supported single cells. Furthermore, a stable current density is obtained for the single cell operating at 600 °C and 0.5 V for 100 h. Analysis of electrochemical impedance spectra (EIS) and distribution of relaxation time (DRT) data at different oxygen partial pressures reveal that the charge-transfer and oxygen ions ionization processes at intermediate frequencies present a significant limiting step in the rate of the oxygen reduction reaction. However, under realistic utilization conditions, cathodes of cells often endure irreversible performance degradation owing to the Cr deposition from interconnects or CO2 poisoning in air. Hence, the behavior of Cr and CO2 poisoning is also systematically investigated in symmetrical cell measurements; the results confirm that the HEP cathode displays good resistance to Cr and CO2 poisoning. Overall, our findings indicate that the HEP material is regarded as a favored ceramic cathode for SOFC.

Comprehensive chemical passivation of active-state heavy metals in relation to soil biological activity in Taojia River basin

Rapid global industrialization has resulted in irreversible environmental degradation, with one pressing issue being the escalating problem of land contamination induced by heavy metals (HMs). This phenomenon not only inflicts lasting harm on plants and microorganisms within the affected regions but also imposes significant losses on various industrial chains, particularly in the realm of agriculture. A noteworthy illustration is the soil contamination in the Taojia River Basin, Hunan Province, China, attributed to mining activities. Therefore, this study is dedicated to examining the passivation of active-state lead (Pb) and cadmium (Cd) in the cultivated fields of the Taojia River Basin. To achieve this, two passivating agents, namely bentonite (referred to as passivator-P) and an acidifying soil agent known as “Shi Di Jia” (referred to as passivator-S), were employed, along with a control group (CK). The passivation of Pb primarily relies on cation exchange adsorbed on the passivator's surface, while the passivation of Cd is intricately linked to total nitrogen content (TN). Indoor incubation tests were conducted to assess Pb and Cd in the soil. Additionally, an analysis of various soil health indicators and their relationships with microbial dynamics and soil enzymes was undertaken. The findings revealed that passivator-P exhibited greater efficacy in the passivation of Pb at concentrations of 3% and 5%, while higher concentrations of passivator-S demonstrated increased effectiveness in passivating Cd. Concerning bacterial diversity, the soil pH post-passivation showed a positive correlation with the Observed_species index, whereas Pb and Cd exhibited negative associations with the Chao1 index. Regarding fungal diversity, soil TN post-passivation displayed a positive correlation with the Simpson index. It is concluded that adding passivator-P at a 3% concentration proved to be the optimal passivating agent for Pb-contaminated soils in the Taojia River Basin. Although passivator-S demonstrated lesser efficacy in passivating Pb, it proved to be suitable for Cd passivation. These findings offer a crucial reference for passivation passivation remediation in the Taojia River area and other sites with similar characteristics, shedding light on the impacts on soil organisms. The implications underscore the necessity for site-specific remediation strategies and a holistic approach to addressing HMs contamination.

Genomic insights into CKX genes: key players in cotton fibre development and abiotic stress responses.

Cytokinin oxidase/dehydrogenase (CKX), responsible for irreversible cytokinin degradation, also controls plant growth and development and response to abiotic stress. While the CKX gene has been studied in other plants extensively, its function in cotton is still unknown. Therefore, a genome-wide study to identify the CKX gene family in the four cotton species was conducted using transcriptomics, quantitative real-time PCR (qRT-PCR) and bioinformatics. As a result, in G. hirsutum and G. barbadense (the tetraploid cotton species), 87 and 96 CKX genes respectively and 62 genes each in G. arboreum and G. raimondii, were identified. Based on the evolutionary studies, the cotton CKX gene family has been divided into five distinct subfamilies. It was observed that CKX genes in cotton have conserved sequence logos and gene family expansion was due to segmental duplication or whole genome duplication (WGD). Collinearity and multiple synteny studies showed an expansion of gene families during evolution and purifying selection pressure has been exerted. G. hirsutum CKX genes displayed multiple exons/introns, uneven chromosomal distribution, conserved protein motifs, and cis-elements related to growth and stress in their promoter regions. Cis-elements related to resistance, physiological metabolism and hormonal regulation were identified within the promoter regions of the CKX genes. Expression analysis under different stress conditions (cold, heat, drought and salt) revealed different expression patterns in the different tissues. Through virus-induced gene silencing (VIGS), the GhCKX34A gene was found to improve cold resistance by modulating antioxidant-related activity. Since GhCKX29A is highly expressed during fibre development, we hypothesize that the increased expression of GhCKX29A in fibres has significant effects on fibre elongation. Consequently, these results contribute to our understanding of the involvement of GhCKXs in both fibre development and response to abiotic stress.