Intrinsic Issues Research Articles

Excess CO2 Reductions during CH3 COOH Formation from CH4 and CO2 under Periodic Operation: Downhill Side Reactions in an Uphill Target Reaction under Unsteady Conditions.

Acetic acid (CH3 COOH) formation from methane (CH4 ) and carbon dioxide (CO2 ) is an ideal reaction for chemical production, whereas this reaction possesses a severe thermodynamic limitation. To address this issue, it has been reported that periodic operation allowing a non-equilibrium condition can overcome the thermodynamic limitation. However, although an intrinsic issue of uphill reactions in non-equilibrium conditions generally is occurrence of unfavorable downhill reactions, this issue has seldom been discussed for the CH3 COOH formation under periodic operation. Herein, excess CO2 reductions were found to be the unfavorable downhill reactions possibly occurring in the reaction aiming at CH3 COOH formation under periodically operated CH4 and CO2 feeds. The reaction using an isotopic reactant (i. e., 13 CH4 ) unveiled that excess CO2 reductions to CO and even to CH3 moiety could occur, indicating importance of catalyst development. Furthermore, it was proposed that H2 O vapor introduction into the CO2 feed, which increased the CH3 COOH product, most likely facilitated the reverse reaction of the excess CO2 reductions and thereby is effective to hamper the unfavorable side reaction.

Surface chemistry engineering of layered oxide cathodes for sodium‐ion batteries

AbstractSodium‐ion batteries (SIBs) have attracted extensive attention to be applied in large‐scale energy storage due to their low cost and abundant storage resources. Among cathode materials for SIBs, layered oxide cathodes are considered one of the most promising candidates for practical application owing to their high theoretical capacities, simple synthesis routes, and environmental friendliness. However, poor air stability, complicated interfacial reaction, and irreversible phase translation of layered oxide cathodes pose problems for the long‐term cycle as well as rate performance. In this review, the recent achievements and progress in surface engineering chemistry strategies to improve the electrochemical performance of SIBs have been summarized including mechanical mixing, in‐situ coating methods, and designing unique interfacial structures. Moreover, inspired by previous studies, we propose an innovative concept of interface conversion reaction with bulk penetration doping integration, which is expected to deal with both interfacial and intrinsic issues synchronously through heat treatment. It could not only eliminate residual sodium compounds on the surface and improve air stability but also suppress the dissolution and the migration of transition metal and the phase transformation. The insights that came up in this review can be considered as a guide for surface engineering on layered oxide cathode for SIBs.

Continual learning fault diagnosis: A dual-branch adaptive aggregation residual network for fault diagnosis with machine increments

As a data-driven approach, Deep Learning (DL)-based fault diagnosis methods need to collect the relatively comprehensive data on machine fault types to achieve satisfactory performance. A mechanical system may include multiple submachines in the real-world. During condition monitoring of a mechanical system, fault data are distributed in a continuous flow of constantly generated information and new faults will inevitably occur in unconsidered submachines, which are also called machine increments. Therefore, adequately collecting fault data in advance is difficult. Limited by the characteristics of DL, training existing models directly with new fault data of new submachines leads to catastrophic forgetting of old tasks, while the cost of collecting all known data to retrain the models is excessively high. DL-based fault diagnosis methods cannot learn continually and adaptively in dynamic environments. A new Continual Learning Fault Diagnosis method (CLFD) is proposed in this paper to solve a series of fault diagnosis tasks with machine increments. The stability–plasticity dilemma is an intrinsic issue in continual learning. The core of CLFD is the proposed Dual-branch Adaptive Aggregation Residual Network (DAARN). Two types of residual blocks are created in each block layer of DAARN: steady and dynamic blocks. The stability–plasticity dilemma is solved by assigning them with adaptive aggregation weights to balance stability and plasticity, and a bi-level optimization program is used to optimize adaptive aggregation weights and model parameters. In addition, a feature-level knowledge distillation loss function is proposed to further overcome catastrophic forgetting. CLFD is then applied to the fault diagnosis case with machine increments. Results demonstrate that CLFD outperforms other continual learning methods and has satisfactory robustness.

Rechargeable Iodine Batteries: Fundamentals, Advances, and Perspectives.

Lattice distortion and structure collapse are two intrinsic issues of intercalative-type electrodes derived from repeated ion shuttling. In contrast, rechargeable iodine batteries (RIBs) based on the conversion reaction of iodine stand out for high reversibility and satisfying voltage output characteristics no matter when dealing with both monovalent and multivalent ions. Foreseeable performance superiorities lead to an influx of considerable focus and thus a renaissance in RIBs. This review provides a comprehensive overview of the fundamental chemistry of RIBs from the perspectives of physicochemical properties, conversion mechanism, and existing issues. Furthermore, we refine the optimization strategies for high-performance RIBs, focusing on physical adsorption and chemical interaction strengthening, electrolytes regulation, and nanoscale-iodine design. Then the pros and cons of tremendous RIBs are compared and specified. Ultimately, we conclude with remaining challenges and perspectives to our best knowledge, which may inspire the construction of next-generation RIBs.

Gender and climate change adaptation: A case of Ethiopian farmers

AbstractThe adverse impacts of climate change, in many cases, aggravate existing gender inequalities and hinder developing countries from achieving the targets set by the United Nations Sustainable Development Goals (SDGs). It is, therefore, crucial to understand whether there exists a gender gap in climate change adaptation and investigate the factors explaining the gap to reduce the vulnerability of the farming households to surging climatic risks. Using data from 2279 farm households in Ethiopia and applying a multivariate probit model and exogenous switching treatment effect regression method, this study examines the existing gender gap in climate change adaptations among farmers in Ethiopia and factors contributing to this relationship. The results show a significant gender gap in climate change adaptation in farming households due to the differences in both observable and unobservable characteristics of male‐ and female‐headed households. It indicates that reducing the gap can enhance climate change adaptation by female‐headed households by almost 19%. Women's workload in household chores significantly reduces their likelihood to adopt climate change adaptation measures. Therefore, unless policies proposed target institutional factors, including social and cultural barriers, traditional gender norms and division of labor, and other intrinsic behavioral issues, addressing only observed characteristics may not fully address the gender gap. To bring about transformational changes in the existing gender norms and social attitudes, long‐term gender‐informed policies are essential, along with short‐term projects, to address the gender gap in climate change adaptation through the provision of equitable opportunities for all.

Variable Learning‐Memory Behavior from π‐Conjugated Ligand to Ligand‐Containing Cobalt(II) Complex†

Comprehensive SummaryIn the information‐explosion era, developing novel algorithms and memristive devices has become a promising concept for next‐generation capacity enlargement technology. Organic small molecule‐based devices displaying superior learning‐memory performance have attracted much attention, except for the existence of poor heat‐resilience and mediocre conductivity. In this paper, a strategy of transforming an organic‐type data‐storage material to metal complex is proposed to resolve these intrinsic issues. A pristine NDI‐derivative (NIPy) and its corresponding Co(II) complex (CoNIPy) are synthesized for the purpose of electrical property investigation. CoNIPy complex‐based memristive device exhibits superior ternary WORM memory performance compared with the binary behavior of NIPy, including >104 s of reading, lower threshold voltage (Vth), 1: 102: 105 of OFF/ON1/ON2 current ratio, and long‐term stability in heating environment. The variable learning‐memory behavior can be attributed to the enhanced ligand‐to‐metal charge transfer (LMCT) and improved redox activity after the introduction of central metal atom and coordination bond. These studies on material innovation and optimal performance are of great importance not only for environmentally‐robust memristive devices but also for practical application of a host of organic electronic devices.

Pattern of ophthalmological and orthopaedic manifestations in pediatric patients of torticollis presenting to the tertiary care hospital of north India

Introduction: Deformity of the neck and limited motion are commonly seen in pediatric orthopedics. The problem may be simply due to an intrinsic cervical issue or may be the manifestation of other underlying problems. To make a diagnosis of the nature and cause of neck deformity in the newborn is very important. Congenital torticollis is a condition that results in the deviation of a child’s head to one side, with accompanying limitation in the range of motion of the neck. Aims and objective: Objective: To investigate the clinical features and outcome of congenital muscular torticollis (CMT) with passive neck motion limitation according to whether the finding on ultrasonography (US) is normal or abnormal. Material and methods: A total of 32 patients with Congenital Muscular Torticollis (CMT) who met eligibility criteria were included: age at presentation 6 month to 1 year, limitation of passive neck rotation or lateral flexion were included in this study. Patients underwent physiotherapy and were followed-up monthly. The clinical research with torticollis at the Variety Center for Craniofacial Rehabilitation was done from 2019 to 2021 retrospectively. Clinical records, standardized medical photographs, and cephalometric radiographs of the affected patients were examined.

Constructing fast ion-transport channels for reversible zinc metal anodes enabled by self-concentration effect

The zinc (Zn) metal batteries suffer from poor plating/stripping behaviors due to the severe dendrite growth and side reactions stemming from the sluggish ion migration at the electrolyte/electrode interface. Despite effectiveness by constructing artificial ion-diffusion layer to alleviate these issues, the intrinsic mechanism of zinc ion (Zn2+) diffusion within the interfacial layer is not well elucidated yet. Here, inspired by the ability of vermiculite (VRM) to promote the self-concentration kinetics of metal ions, this intrinsic issue can be tackled by elaborately constructing VRM with fast ion-transport channels on the surface of Zn metal anodes. This unique ion channel with a natural negatively charged wall can accelerate Zn2+ transport and reduce the presence of water molecules in Zn2+ solvated shell, which can be demonstrated by molecular dynamic simulation. As a proof of concept, the symmetric cell with VRM@Zn anode achieves dendrite-free plating/stripping with a stable cycling life (580 h) even at a high rate of 25 mA cm−2 with a capacity of 12.5 mAh cm−2. Meanwhile, the Zn-carbon supercapacitor with VRM@Zn anode exhibits an extended stability over 5000 cycles at 1 A g−1. This work reveals the internal mechanism of Zn2+ diffusion within the interfacial layer, and provides an avenue for constructing highly reversible Zn metal anode.

Stabilizing Li-O2 Batteries with Multifunctional Fluorinated Graphene.

As a full cell system with attractive theoretical energy density, challenges faced by Li-O2 batteries (LOBs) are not only the deficient actual capacity and superoxide-derived parasitic reactions on the cathode side but also the stability of Li-metal anode. To solve simultaneously intrinsic issues, multifunctional fluorinated graphene (CFx, x = 1, F-Gr) was introduced into the ether-based electrolyte of LOBs. F-Gr can accelerate O2- transformation and O2--participated oxygen reduction reaction (ORR) process, resulting in enhanced discharge capacity and restrained O2--derived side reactions of LOBs, respectively. Moreover, F-Gr induced the F-rich and O-depleted solid electrolyte interphase (SEI) film formation, which have improved Li-metal stability. Therefore, energy storage capacity, efficiency, and cyclability of LOBs have been markedly enhanced. More importantly, the method developed in this work to disperse F-Gr into an ether-based electrolyte for improving LOBs' performances is convenient and significant from both scientific and engineering aspects.

Growth Hormone Stimulation Testing: To Test or Not to Test? That Is One of the Questions.

The evaluation of children with short stature includes monitoring over a prolonged period to establish a growth pattern as well as the exclusion of chronic medical conditions that affect growth. After a period of monitoring, evaluation, and screening, growth hormone stimulation testing is considered when the diagnosis of growth hormone deficiency (GHD) is entertained. Though flawed, growth hormone stimulation tests remain part of the comprehensive evaluation of growth and are essential for the diagnosis of growth hormone (GH) deficiency. Variables including testing length, growth hormone assay and diagnostic cut off affect results. Beyond the intrinsic issues of testing, results of GH stimulation testing can be influenced by patient characteristics. Various factors including age, gender, puberty, nutritional status and body weight modulate the secretion of GH.

Analyzing micromachining errors in EDM of Inconel 600 using various biodegradable dielectrics

Inconel 600 is a Ni-based superalloy having exclusive properties like high strength and stability in harsh conditions. However, its accurate machining is challenging via conventional cutting methodologies. As a result, the use of electric discharge machining is common in cutting Inconel 600 precisely. But the intrinsic issue of overcut associated with traditional EDM limits its appreciation in cutting Ni-based alloy. Moreover, conventional dielectric oil used in EDM releases hazardous fumes and gases that put the operator’s health at risk. Therefore, in this study, six different biodegradable dielectrics have been investigated for their potential in controlling the dimensional overcut, which have yet to be evaluated thoroughly. The performance of biodegradable dielectrics (canola, amla, olive, sunflower, coconut, and mustard oil) against four types of electrode materials has been evaluated using full factorial design in the EDM of Inconel 600. Experimental findings are analyzed with statistical tests and optical/scanning electron microscopic evidence. The experimental results indicated that canola dielectric yield the smallest dimensional overcut. However, combination of sunflower oil and copper electrode proved as second premier case to reduce the overcut. Compared to the conventionally used kerosene oil, the biodegradable dielectrics (canola and sunflower) display a 63% and 1.2-folds reduction in overcut.

Lithium Bromide-Induced Organic-Rich Cathode/Electrolyte Interphase for High-Voltage and Flame-Retardant All-Solid-State Lithium Batteries.

Poly(ethylene oxide) (PEO)-based solid electrolyte suffers from limited anodic stability and an intrinsic flammable issue, hindering the achievement of high energy density and safe all-solid-state lithium batteries. Herein, we surprisingly found out that a bromine-rich additive, decabromodiphenyl ethane (DBDPE), could be preferably oxidized at an elevated voltage and decompose to lithium bromide at an elevated potential followed by inducing an organic-rich cathode/electrolyte interphase (CEI) on NCM811 surface, enabling both high-voltage resistance (up to 4.5 V) and flame-retardancy for the PEO-based electrolyte. On the basis of this novel solid electrolyte, all-solid-state Li/NCM811 batteries deliver an average reversible capacity of 151.4 mAh g-1 over the first 150 cycles with high capacity retention (83.0%) and high average Coulombic efficiency (99.7%) even at a 4.5 V cutoff voltage with a unprecedented flame-retardant properties. In view of these exploration, our studies revealed the critical role of LiBr in inducing an organic-rich thin and uniform CEI passivating layer with enhanced lithium ion surface diffusion and high-voltage resistant properties, which provides a new protocol for the further design of a high-voltage PEO-based all-solid-state electrolyte.

Quantum Squeezing and Sensing with Pseudo-Anti-Parity-Time Symmetry.

The emergence of parity-time (PT) symmetry has greatly enriched our study of symmetry-enabled non-Hermitian physics, but the realization of quantum PT symmetry faces an intrinsic issue of unavoidable symmetry-breaking Langevin noises. Here we construct a quantum pseudo-anti-PT (pseudo-APT) symmetry in a two-mode bosonic system without involving Langevin noises. We show that the spontaneous pseudo-APT symmetry breaking leads to an exceptional point, across which there is a transition between different types of quantum squeezing dynamics; i.e., the squeezing factor increases exponentially (oscillates periodically) with time in the pseudo-APT-symmetric (broken) region. Such dramatic changes of squeezing factors and quantum dynamics near the exceptional point are utilized for ultraprecision quantum sensing. These exotic quantum phenomena and sensing applications can be experimentally observed in two physical systems: spontaneous wave mixing nonlinear optics and atomic Bose-Einstein condensates. Our Letter offers a physical platform for investigating exciting APT symmetry physics in the quantum realm, paving the way for exploring fundamental quantum non-Hermitian effects and their quantum technological applications.

Cellulose nanocrystal chiral photonic micro-flakes for multilevel anti-counterfeiting and identification

Counterfeiting and forgery have caused enormous economic loss and many safety concerns, and many approaches have been employed for anti-counterfeiting. However, most of these approaches suffer intrinsic issues such as replicability, environmental sustainability, or the requirement of professional equipment to authenticate. Cellulose nanocrystal (CNC) chiral photonic films prepared by evaporation induced self-assembling display iridescent structural colors, circular dichroism, and unique fingerprint texture in microsize, which are promising for anti-counterfeiting. However, the application of CNC films in anti-counterfeiting are severely limited by their brittleness and nonuniformity. Herein, CNC chiral photonic micro-flakes facilely prepared via ultrasonication of CNC films preserve the optical characteristics of CNC chiral photonic films, and can be mixed with polymer matrices to fabricate flexible films or coatings for practical anti-counterfeiting and identification. The anti-counterfeiting characteristics of CNC chiral photonic micro-flakes can be authenticated by an inspection with naked eyes, using 3D glasses, and further with a polarized optical microscope. Therefore, CNC chiral photonic micro-flakes provide a non-replicable, environmentally friendly, easy-to-authenticate, and practical approach for multilevel anti-counterfeiting and identification.

Investigating cryogenically treated electrodes’ performance under modified dielectric(s) for EDM of Inconel(617)

ABSTRACT Inconel 617 has unique characteristics however it is extremely difficult to machine this alloy with conventional processes. Thereof, generally electric discharge cutting (EDM) is engaged for its precise cutting. The intrinsic issue of low machining rate in EDM confines its application. Therefore, this problem has been comprehensively examined herein employing different cryogenically treated electrodes, which has not been targeted so far. Moreover, the potentiality of modified dielectrics in the aforementioned context using the both cryogenic treated and non-treated electrodes have also been investigated. Experimentation was performed using three types of electrodes against five types of dielectric media under full factorial design. Total 30 experiments were performed. The electrode of Cu has outperformed in terms of material removal rate (MRR) in both treated and non-treated forms. The highest magnitude of MRR (15.66 mm3/min) has been achieved using a blend of Span-20 and kerosene dielectric. Cryo-trated brass has provided 95.2% higher MRR than that obtained with non-deep cryogenic treated (non-DCT) brass using kerosene as dielectric. Cryo-treated graphite tool produced the largest MRR (4.6 mm3/min) when T-20 mixed kerosene is used. Span-20 added kerosene is the best choice for getting high MRR if non-DCT electrodes are used whereas Tween-20 mixed kerosene is best suited for cryo-treated electrodes.

Neutronic analysis of silicon carbide Cladding-ATF fuel combinations in small modular reactors

With more attention being paid to the development of small modular reactors (SMR), the intrinsic safety issues have reached a critical point. Accident-tolerant fuel (ATF), such as the U3Si2, UO2-BeO, silicon carbide cladding etc. can maintain or improve fuel performance under normal reactor operating conditions and can maintain core integrity for a long period after the design-basis accident scenarios, providing a sufficient time margin to take measures. Therefore, applying the ATF to the SMR also enables the possibility of operating the SMR more safely. Most neutronic analyses of the ATF, however, have focused on the large-scale commercial pressurized water reactor. In this study, we adopted a given ATF design (the combination of U3Si2 and silicon carbide cladding) and compared it with other combinations of fuel and three different types of silicon carbide claddings in one single-fuel assembly and the full core of the mPower. We evaluated and analyzed the aspect of neutronic physics with Serpent-2 and OpenMOC computational codes. The results for the full core showed that the core life of U3Si2-SiC could be increased by 3.1% which feasibly could be used in the SMR from the neutronic point of view. The U3Si2, however, had a lower effect on neutron absorption than the UO2 when using the burnable poison rod in the full core. The neutronic penalties of different types of silicon carbide cladding were not significant in the SMR. Overall, the silicon carbide cladding-ATF fuel combinations were feasible for use in the mPower SMR.

Plasmonic Local Heating Induced Strain Modulation for Enhanced Efficiency and Stability of Perovskite Solar Cells

AbstractThe residual strain induced during the growth of perovskite film is an intrinsic issue that significantly affects the efficiency and stability of perovskite solar cells (PVSCs). Inspired by the flipped annealing method to release strain in perovskite thin films, SiO2‐coated gold nanorods (GNR@SiO2) are introduced into perovskite film and advantage of the plasmonic local heating effect is taken for in situ strain relaxation. The GNR@SiO2‐incorporated inverted PVSCs exhibit a champion power conversion efficiency (PCE) over 23%, which is the highest PCE in plasmonic‐incorporated PVSCs. Moreover, the intrinsic stability of the resulting PVSCs is greatly improved for the nonencapsulated device and retains 84% of its initial PCE after 2800 h aging under continuous illumination at 65 ± 5 °C in an N2 glove box and nearly 90% after 1000 h repetitive 12 h light on–off cycles. This work provides an efficient yet easy‐to‐implement plasmonic heating strategy for simultaneously enhancing the efficiency and stability of PVSCs.

Plasticization-enhanced trimethylbenzene functionalized polyethersulfone hollow fiber membranes for propylene and propane separation

Polymeric membranes for gas separations often suffer from plasticization, which leads to the swelling of polymer matrices and thus the loss of the separation selectivity and performance. Such intrinsic and detrimental issues remain challenging and unsolved. Here, we report a newly designed polymer, poly trimethyl phenylene ethersulfone (PTPES) that is a trimethylbenzene-functionalized polyethersulfone and beneficial from the plasticization. When the polymer is fabricated into defect-free hollow fiber membranes, both propylene permeance and propylene/propane selectivity increase exponentially with the feed pressure after plasticization. The PTPES hollow fibers have a propylene permeability and a propylene/propane selectivity about two orders of magnitude higher than their intrinsic values of dense films. The exceptionally plasticization-enhanced phenomena of PTPES hollow fibers might be ascribed to the unique plasticization-enlarged steric-hindrance molecular sieving effect, which happens in the ultra-thin PTPES skin layer and is caused by the trimethylbenzene moieties in the well-oriented polymer chains. Our work provides new insights to the membrane gas transport mechanisms and may inspire the development of new-generation polymeric materials and membranes for propylene/propane and other gas separations.

Disrupting Sodium Ordering and Phase Transitions in a Layered Oxide Cathode

Layered Nax MO2 cathodes are of immense interest as rechargeable sodium batteries further their development as a lithium-ion battery alternative. However, two primary intrinsic structural issues hinder their practicality—sodium ordering and transition-metal layer gliding during cycling. These phenomena plague the electrochemical profiles of these materials with several unwanted voltage plateaus. A Na+ and Fe3+ substitution for Ni2+ strategy is employed here to obtain a series of Na3+x Ni2–2x Fe x SbO6 (0 ≤ x ≤ 0.5) materials to suppress the structural phenomena that are apparent in O’3-layered Na3Ni2SbO6 cathode material. This strategy is successful in obtaining a sloping voltage curve without distinct plateaus—an indication of suppression of the underlying structural phenomena that cause them—at doping concentrations of x ≥ 0.3. The first-cycle coulombic efficiency of the doped compounds is much greater than the starting compound, presumably owing to a kinetic barrier to reforming the full O’3-layered starting materials within the voltage range of 2.5–4.3 V vs Na+/Na. Sodium doping into the MO2 layer thus remains a promising strategy for enabling commercial Na x MO2 cathodes, but further development is required to lower the kinetic barrier for sodium reinsertion into these materials in a useful voltage range to maximize their reversible capacity.

Comparison of electrical characteristics of Schottky junctions based on CdS nanowires and thin film

CdS nanowires and film Schottky diodes are fabricated and diode properties are compared. Effect of SnO2 on CdS film diode properties is investigated. CdS film/Au on 100 nm SnO2 substrate demonstrates like-resistor characteristics and increase in SnO2 thickness corrects resistor behavior, however the effective reverse saturation current density J o is significantly high and shunt resistance are considerably low, implying that SnO2 slightly prevents impurities migration from CdS films into ITO but cause additional issues. Thickness of CdS film on diode properties is further investigated and increasing CdS film thickness improved J o by one order of magnitude, however shunt resistance is obviously low, suggesting intrinsic issues in CdS film. 100 nm CdS nanowire/Au diodes reduce J o by three orders of magnitude in the dark and two orders of magnitude in the light respectively and their shunt resistance is significantly enhanced by 70 times when comparing with those of the CdS film diodes. The wide difference can be attributed to the fact that CdS nanowires overcome intrinsic issues in CdS film and thus demonstrate significantly well- defined diode behavior. Simulation found that CdS nanowire diodes have low compensating acceptor type traps and interface state density of 5.0 × 109 cm−2, indicating that interface recombination is not a dominated current transport mechanism in the nanowire diodes. CdS film diodes are simulated with acceptor traps and interface state density increased by two order of magnitude and shunt resistance reduced by one order of magnitude, indicating that high density of interface states and shunt paths occur in the CdS film diodes.