Millimeters In Length Research Articles

Surgical Anatomy of the Lateral Thoracic Artery and Its Perforators: A Computed Tomographic Angiography and Cadaveric Dissection Study

Objective: This study explores the anatomical variations and characteristics of the lateral thoracic artery (LTA) and its perforators through thoracic computed tomographic angiographies (CTA) and cadaveric dissection, aiming to enhance surgical planning and patient outcomes. Materials and Methods: Data were recorded for both thoracic CTA patients (n = 40) and soft cadavers (n = 13) for subsequent retrospective analyses of biological sex, age, body mass index (BMI), LTA characteristics (length, diameter, origin, number of perforators, number of lymph nodes), and locations (rib level and distance from the pectoralis major, latissimus dorsi, and acromioclavicular joint). Results: Average LTA parameters for thoracic CTAs were 89.6 millimeters in length from origin and 2.1 millimeters in diameter, while cadavers were 117.0 millimeters in length and 2.3 millimeters in diameter. At least 1-2 cutaneousperforators and 1 proximal lymph node were found across both thoracic CTAs and cadavers. No significant differences were observed between the left and right sides for both groups. On average, 73.8% and 66.4% of LTAs from thoracic CTAs and cadavers, respectively, originated from the axillary artery. Conclusion: This knowledge is crucial for surgical planning, both to minimize damage to the LTA and ensure the inclusion of its perforators and proximal lymph nodes in the lateral thoracic region. The researchers recommend lateral thoracic artery perforator flap harvest between the lateral border of the pectoralis major and the anterior border of the latissimus dorsi, specifically above the 3rd-6th ribs, which is correlated to the length of LTA at 89.6-117 millimeters from origins.

Detection of Defects in Polyethylene and Polyamide Flat Panels Using Airborne Ultrasound-Traditional and Machine Learning Approach

This paper presents the use of noncontact ultrasound for the nondestructive detection of defects in two plastic plates made of polyamide (PA6) and polyethylene (PE). The aim of the study was to: (1) assess the presence of defects as well as their size, type, and orientation based on the amplitudes of Lamb ultrasonic waves measured in plates made of polyamide (PA6) and polyethylene (PE) due to their homogeneous internal structure, which mainly determined the selection of such model materials for testing; and (2) verify the possibilities of building automatic quality control and defect detection systems based on ML based on the results of the above-mentioned studies within the Industry 4.0/5.0 paradigm. Tests were conducted on plates with generated synthetic defects resembling defects found in real materials such as delamination and cracking at the edge of the plate and a crack (discontinuity) in the center of the plate. Defect sizes ranged from 1 mm to 15 mm. Probes at 30 kHz were used to excite Lamb waves in the slab material. This method is sensitive to the slightest changes in material integrity. A significant decrease in signal amplitude was observed, even for defects of a few millimeters in length. In addition to traditional methods, machine learning (ML) was used for the analysis, allowing an initial assessment of the method’s potential for building cyber-physical systems and digital twins. By training ML models on ultrasonic data, algorithms can distinguish subtle differences between signals reflected from normal and defective areas of the material. Defect types such as voids, cracks, or weak bonds often produce distinct acoustic signatures, which ML models can learn to recognize with high accuracy. Using techniques like feature extraction, ML can process these high-dimensional ultrasonic datasets, identifying patterns that human inspectors might overlook. Furthermore, ML models are adaptable, allowing the same trained algorithms to work on various material batches or panel types with minimal retraining. This combination of automation and precision significantly enhances the reliability and efficiency of quality control in industrial manufacturing settings. The achieved accuracy results, 0.9431 in classification and 0.9721 in prediction, are comparable to or better than the AI-based quality control results in other noninvasive methods of flat surface defect detection, and in the presented ultrasonic method, they are the first described in this way. This approach demonstrates the novelty and contribution of artificial intelligence (AI) methods and tools, significantly extending and automating existing applications of traditional methods. The susceptibility to augmentation by AI/ML may represent an important new property of traditional methods crucial to assessing their suitability for future Industry 4.0/5.0 applications.

Modified Tap-drilling Technique for Mid-cervical Pedicle Screw Placement: A Case Series of 473 Consecutive Screws.

Retrospective cohort study. To report our modified tap-drilling technique for mid-cervical pedicle screw placement and to evaluate its safety and accuracy. Cervical pedicle screw fixation, which provides a strong stabilization, has been a major concern due to the potential risks to neurovascular structures despite its increasing use. Several insertion techniques have been described so far to improve the cervical pedicle screw placement accuracy. This study retrospectively reviewed patients who underwent mid-cervical (C3-C6) pedicle screw fixation between September 2005 and September 2020. Laminectomy, laminoforaminotomy, or notch-referred anatomic landmark methods were used to adjust the entry point and the direction of the screws. After the cortical bone was removed at the entry point with a diamond burr, the cancellous bone was slowly drilled with a hand drill starting from 8 to 10 millimeters in length. Then, all of the bone walls were checked with a ball-tip probe to determine if there was any breach. The procedure was repeated several times. After completing the drilling, the screw was inserted without tapping. The breach rate of pedicle screws was analyzed on postoperative computed tomography scans. A total of 473 mid-cervical pedicle screws were placed in 122 consecutive patients. No navigation or computer-assisted system was used, and the first 2 authors inserted all of the screws. All patients completed the surgery, and no evident intraoperative complications occurred. Postoperative CT scans were obtained for 405 screws. Although deviation was observed for 131 pedicle screws, a critical deviation was observed for only 25 pedicle screws. Cervical pedicle screw insertion is a risky but applicable technique. Checking all of the bone walls with a ball-tip probe before gradually advancing the hand drill in small amounts, as presented in this article, may lead to the safe and effective placement of cervical pedicle screws.

Surface-Guided Crystallization of Xanthine Derivatives for Optical Metamaterial Applications.

Numerous bio-organisms employ template-assisted crystallization of molecular solids to yield crystal morphologies with unique optical properties that are difficult to reproduce synthetically. Here, a facile procedure is presented to deposit bio-inspired birefringent crystals of xanthine derivatives on a template of single-crystal quartz. Crystalline sheets that are several millimeters in length, several hundred micrometers in width, and 300-600nm thick, are obtained. The crystal sheets are characterized with a well-defined orientation both in and out of the substrate plane, giving rise to high optical anisotropy in the plane parallel to the quartz surface, with a refractive index difference Δn ≈ 0.25 and a refractive index along the slow axis of n ≈ 1.7. It is further shown that patterning of the crystalline stripes with a tailored periodic grating leads to a thin organic polarization-dependent diffractive meta-surface, opening the door to the fabrication of various optical devices from a platform of small-molecule based organic dielectric crystals.

Characterization of superconducting through-silicon vias as capacitive elements in quantum circuits

The large physical size of superconducting qubits and their associated on-chip control structures presents a practical challenge toward building a large-scale quantum computer. In particular, transmons require a high-quality-factor shunting capacitance that is typically achieved by using a large coplanar capacitor. Other components, such as superconducting microwave resonators used for qubit state readout, are typically constructed from coplanar waveguides, which are millimeters in length. Here, we use compact superconducting through-silicon vias to realize lumped-element capacitors in both qubits and readout resonators to significantly reduce the on-chip footprint of both of these circuit elements. We measure two types of devices to show that through-silicon vias are of sufficient quality to be used as capacitive circuit elements and provide a significant reduction in size over existing approaches.

Progression of parasitism from phoresy in mites

The mites are the smallest (less than a millimeter in length), the most diverse, and the most common of all arachnids. Mites are ubiquitous and inhabit all known terrestrial, marine, and freshwater habitats, including arctic and alpine extremes, tropical plains and desert barrens, and surface and mineral soils (Dunlop and Alberti, 2008). More than 55,000 species have been described up to date, accounting for 5% of all living species today. Mites are experts at transport with the aid of large animals, mostly insects. It is a temporary relationship called phoresy that allows the mites to exploit scarce resources. Phoresy in the subclass Acari includes insects that feed on carriers. Phoresy evolved from free-living ancestors. The primary waste material used by floating mites appears to be rotting logs. However, rapid changes in the later life stage allowed the development of short-term resources. Although phoresy is a form of social interaction, most interact with mites. These relationships can be very complex and context-specific, but they often use the vector's sources or descendants (Seeman and Walter, 2023). The switch from phoretic to parasitism seems popular, but the scientific evidence for a switch from phoretic to permanent parasitism seems to be lacking.

Temperature-Dependent Sheet Resistance and Surface Characterization of Thin Copper Films Bonded to FR4 Composite under Mechanical Vibrations

Electrical boards, also called printed circuit boards, constitute the basis of most electronic devices. These boards are mainly fabricated of thin copper films bonded to fiber epoxy laminates, such as FR4. Being the most important functional component of these devices, they sometimes undergo mechanical stresses such as shock and vibration during transport and operation that can induce electrical failure and malfunction; hence, studies addressing the effects of vibrations on their electrical properties have important applications. In this paper, small cantilever samples made of bare copper bonded to FR4 with three isolated rectangular zones were studied to analyze, for the first time, variations in electrical properties such as sheet resistance and resistivity before and after 200 k, 500 k, and 800 k vibration cycles at three different temperatures (25, 35, and 45 °C). A significant rise in resistance equivalent to 1657% of the initial value was observed from 0 to 800 k vibration cycles. These changes were accompanied by a 95% decrease in conductivity, from 4.1 × 107 to 2.3 × 106 S/m, whereas very little change in the electrical properties was observed due to temperature rise. Surface analysis by ESEM showed cracks ~1 µm in width and several millimeters in length with a crack density of ~8 cracks per mm after 800 k cycles. The surface composition (100% copper) was not altered even upon a high number of vibration cycles, and static drop contact angle measurements of 117–119 degrees indicated an increase in the hydrophobicity of the surface attributed to increased surface roughness and the accumulation of very small air bubbles on the cracks.

Traumatic endophthalmitis following injury by a fish: A rare case report and review of literature

A 26-year-old male presented with decreased vision in left eye (OS) following an attack by a fish while swimming in a pond. His best corrected visual acuity (BCVA) was hand movements in OS and 20/20 in right eye (OD). Fundus examination and ultrasonography B-scan confirmed the presence of traumatic endophthalmitis in OS. Wound exploration confirmed the presence of a foreign body near limbus, which was removed and found to be a cartilaginous fish tissue measuring 4.5 millimeters in length. Pars plana vitrectomy was performed, and intravitreal antibiotics were administered. The case highlights a rare form of ocular injury and its management.

Tool for automatic macrozone characterization from EBSD data sets of titanium alloys.

Microtexture heterogeneities are commonly found in titanium forgings because of the thermomechanical processing. Also known as macrozones, these regions can reach millimetres in length, with grains sharing a similar crystallographic orientation leading to less resistance to crack propagation. Since the link between macrozones and the reduction of cold-dwell-fatigue performance on rotative components in gas turbine engines was established, efforts have been put into macrozone definition and characterization. The electron backscatter diffraction (EBSD) technique, widely used for texture analysis, allows for a qualitative macrozone characterization; however, further processing is required to define the boundaries and disorientation spread of each macrozone. Current approaches often use c-axis misorientation criteria, but this can sometimes lead to a large disorientation spread within a macrozone. This article describes the development and application of a computational tool implemented in MATLAB for automatic macrozone identification from EBSD data sets on the basis of a more conservative approach where both the c-axis tilting and rotation are considered. The tool allows for detection of macrozones according to the disorientation angle and density-fraction criteria. The clustering efficiency is validated by pole-figure plots, and the effects of the key parameters defining the macrozone clustering (disorientation and fraction) are discussed. In addition, this tool was successfully applied to both fully equiaxed and bimodal microstructures of titanium forgings.

In-Vitro Effect of Effectively of G-Bond and Z-Prime Plus in Prevention of Fracture of Prefabricated Zirconia Posts Bonded to Root Canal Walls

Background and Aim: The purpose of this research was to examine the influence of Z-Prime Plus and G-Bond on zirconia posts fracture resistance affixed to the walls of root canals. Place of Study: Avicenna Medical College Lahore Study Duration: March 2021 to April 2022 Materials and Methods: In this in-vitro experimental study, the diameter and length of each of the 20 mandibular premolars used were identical. This assured that the study's findings were comparable. Once a cut was made at the cementoenamel junction (CEJ) to prepare the teeth for root canal therapy, the teeth were randomly assigned to one of two groups (n=11) with the same number of teeth in each group. In the experiment, a single tooth from each group was chosen at random to serve as the control. A post space of approximately 10 millimeters in length was established in the remaining teeth. The following process involved etching the intracanal dentin, followed by rinsing and drying the material. The technique involved filling the canal with Panavia F2 resin cement. After applying G-Bond and Z-Prime Plus to the zirconia posts in respectively, groups 1 and 2, the placement of post was done in the canals and subsequently cemented. The photo core resin composite material was utilized in the fabrication of the cores. The longitudinal axis of the teeth was compressed by a force application to the core of central fossa o at a crosshead speed of 0.5 millimeters per minute. This was accomplished with a crosshead speed of 0.5 mm/min. The load that caused the fracture was measured and documented. To analyze the data, a t-test was conducted, and a normal distribution was also taken into account. Result: The results indicated that the average fracture resistance of G-Bond was 1088.1±330 while the average fracture resistance of Z-Prime Plus was 898.4±369 however, the difference was not statistically significant (P=0.3). Practical Implication: The influence of Z-Prime Plus and G-Bond on zirconia posts fracture resistance affixed to the walls of root canals Conclusion: There was no significant difference between the fracture resistance of zirconia posts bound with G-Bond and Z-Prime Plus to root canal walls. In contrast, G-Bond is highly advised for usage in this application due to its decreased coefficient of variation (CV) and significantly increased fracture resistance. This makes it a great option for the current endeavor. Keywords: Primer; resin composite; shear bond strength; zirconia ceramic, G-Bond, Post and Core Technique, Z-Prime Plus

A Retrospective Evaluation of the Clinical Outcome of Dental Implants Following Maxillary Sinus Augmentation with and without Bone Grafting

The reintegration of partial edentulism patients is the utmost common treatment performed by dental practitioners in relations of frequency & occurrence, even though the general decline in tooth loss seen in recent times. There is broad agreement among dental professionals that osseointegrated implant-supported prostheses are the preferred method for replacing an edentulous gap caused by one or more lost teeth. These implants have been shown to provide several benefits for both physical and mental health. Objectives: The current retrospective study sought to define and assess the 60 months follow-up of implants inserted in patients who needed sinus floor elevation surgery in the maxillary arch. Following a single-stage surgical method with delayed implant insertion, the impact of various RABH & the usage of graft and graft less methods were evaluated. Methodology: Patients chosen for the current retrospective study were selected from the data-based logbooks kept by the oral surgery department between January 2017 and December 2022. All patients who had concomitant lateral sinus floor elevation & implant insertion from the same department were evaluated in the current study after obtaining formal approval from the IRB of the institute. Results: 86 grafted sinuses received a sum of 239 implants, each assessing 10 & 12 millimeters in length and 4 or 5 mm in breadth. Specific measurements revealed that the majority were 4 mm broad & 10 mm long. Using a manual torque wrench, it was determined that all implants, regardless of size, attained an insertion torque of >35 Ncm at the moment of implantation. In 41 patients, xenograft was employed, corresponding to 60 sinuses; in contrast, in 45 patients, graft-less surgery was performed, corresponding to 62 sinuses. An average follow-up of 43 months was used. Conclusion: Maxillary sinuses with a RABH of more than four millimeters can be effectively transplanted using a single-stage xenograft technique. One-stage graft-less surgeries with blood clot alone & swift implant implantation should only be used in sinuses with a RABH > 6 mm since they have lower success rates. Practical Implication: The following study will help oral surgeon in choosing the surgery carried out for the implant placement involving the sinuses. Keywords: Dental Implants, Bone Replacements, Sinus Augmentation, Grafting Materials

Kelimpahan dan Jenis Mikroplastik pada Sedimen Lamun di Perairan Nusa Dua, Bali

The Indonesian archipelago, especially Bali, has extensive coastline and marine waters. However, it is undeniable that some of these waters contain much plastic waste. Nusa Dua waters are located in the Bali Province area with many complex activities, ranging from port activities, water sports, tourism, restaurants, hotels, fishing activities, and others, so they have a high potential for plastic waste pollution. Plastic waste that floats in the ocean will degrade and become small debris called microplastics. Marine plastic debris is divided into several varieties based on size. It is called microplastic for those less than 5 millimeters in length; for those above 5 mm and up to 25 mm, it is mesoplastic. This study aimed to determine the abundance and types of microplastics found in Nusa Dua. This research was conducted in November-Desember 2021. Sampling was carried out in situ with the simple random sampling method of 400 grams of each sample at ten stations. Sediment sampling was carried out using a shovel. Then the ex-situ processing was carried out by drying wet sediment, weighing dry sediment, density separation, filtering, and visual sorting. The results showed that the seagrass sediments in Nusa Dua waters were contaminated with microplastic. Four types of microplastic were found: fragment, fiber/filament, film/soft plastic, and foam. As many as 17 particles fragment the type of microplastic that dominates. The dominant color is blue. The highest total abundance of microplastics was found at station 6, as much as 35.1 particles/kg with different densities of seagrass species at each station. The density of seagrass species itself reaches the range of 1.2 stands/m2

Insights into Cell-Specific Functions of Microtubules in Skeletal Muscle Development and Homeostasis.

The contractile cells of skeletal muscles, called myofibers, are elongated multinucleated syncytia formed and maintained by the fusion of proliferative myoblasts. Human myofibers can be hundreds of microns in diameter and millimeters in length. Myofibers are non-mitotic, obviating the need for microtubules in cell division. However, microtubules have been adapted to the unique needs of these cells and are critical for myofiber development and function. Microtubules in mature myofibers are highly dynamic, and studies in several experimental systems have demonstrated the requirements for microtubules in the unique features of muscle biology including myoblast fusion, peripheral localization of nuclei, assembly of the sarcomere, transport and signaling. Microtubule-binding proteins have also been adapted to the needs of the skeletal muscle including the expression of skeletal muscle-specific protein isoforms generated by alternative splicing. Here, we will outline the different roles microtubules play in skeletal muscle cells, describe how microtubule abnormalities can lead to muscle disease and discuss the broader implications for microtubule function.

Efficacy of electrolytic treatment on degrading microplastics in tap water

Microplastics, or plastic fibers less than five millimeters in length, are a significant environmental problem and are extremely difficult to remove from water. In this experiment, we quantified the effect of electrolysis on the degradation of microplastics in tap water and explored electrolysis as a potential solution to this issue. We hypothesized that an electrolytic treatment would disassemble microplastic molecules, as it does with water. Treated water consisted of samples electrolyzed for 30 minutes in an electrolysis machine, while samples of untreated tap water were the control. We examined filters under a microscope before and after filtration of the water samples to determine the number of net microplastics in every sample. Overall, control samples demonstrated a greater number of net microplastics than experimental samples (Mann-Whitney U, p = 0.047). Thus, we conclude that electrolysis is a valid and practical method to degrade microplastics in tap water because of its high efficiency within a short duration of time. These findings could be of great value as they have the potential to improve the quality of drinking water, and by extension, public health. This research indicates electrolysis could be advantageous over many other methods of water purification in respect to microplastics.

Practice of Pediatric Spinal Anesthesia in a Country with Limited Means: Example of Togo

Introduction: The practice of spinal anesthesia in pediatric surgery is declining, especially in countries with limited means. What about in our context? Objective: To evaluate the practice of spinal anesthesia in pediatric surgery in Togo. Framework and method of study: This was a prospective study from November 2017 to May 2018 in pediatric surgery at CHU SO de Lomé, in the operating room and hospital ward of CHU Kara. The surgical, anesthesiological and evolutionary aspects of the patients were analyzed. Results: Sixty children were selected for the study who had an indication for sub-umbilical surgery. The male sex was predominant (73.3%). 47 (78.30%) patients were operated on for scheduled surgery. Hernia repair was the most performed surgical intervention (43.30%). The mean duration of the surgery was 78 ± 35.9 minutes. Most of the patients were ASA 1 (98.30%). The local anesthetic used was 0.5% isobaric Bupivacaine. Fentanyl was the predominant adjuvant (55%). The most widely used lumbar puncture needle was 25 Gauge with 75 millimeters in length (63.30%). Diazepam was the most widely used sedative (50%). The predominant spinal anesthesia protocol was spinal anesthesia alone (60%). Only one patient had hypotension (1.70%). Conclusion: The fairly satisfactory pediatric spinal anesthesia in Togo remains poorly performed. Its promotion involves the training of anesthesia practitioners and the strengthening of the technical platform.

The Design of a Plastic Shredder Machine with The Crusher Cutting Knife Model for Environmentally Sustainable

Indonesia produced about 31.2 million metric tons of garbage in 2021. Roughly 87.1% of the total waste is comprised-evaluated of plastic waste. Plastic waste takes a very long time to break down in the environment. It took decades for trash made of plastic to decompose. Disorganized waste management at the landfill is a significant source of plastics-related problems. In order to reuse plastic garbage, it must be crushed up first before the recycling process. The primary objective of the design process for the crushing plastic machine used to shred plastic waste was to maximize productivity. The design of the machine that crushes plastic waste was created and prepared with the help of computer-aided design (CAD) and computer-aided manufacturing (CAM) software. One thousand and zero millimeters in length, three hundred and twenty millimeters in width, and twelve hundred and sixty millimeters in height describe this machine for chopping up plastic trash. In terms of crushing time and capacity, variations in the rotational speed of 1000, 1100, and 1200 blades in revolution per minute were optimal. The optimal crushing time for 2 kg-HDPE plastic waste was 37 seconds at 1200 revolutions per minute, followed by 1100 revolutions per minute; 2 kg-HDPE plastic waste was crushed and evaluated. HDPE plastic wastes have typically crushed faster in less time than PET plastic wastes. It has been evaluated and validated for any setting variation operation involving the crushing speed. Three kilograms of HDPE plastic waste yielded an optimum crushing capacity of 194.4 kg/hour at 1200 revolutions per minute. Next, at 1200 revolutions per minute, 2 kg-HDPE plastic waste is crushed. HDPE plastic wastes are typically more effective to crush than PET plastic wastes, regardless of the crushing speed setting variation operations. As a result of this study, plastic waste is being put to better use, helping to cut down on overall plastic use in the plastic waste management

Ultralong waveguide grating antenna enabled by evanescent field modulation.

Waveguide grating antenna (WGA) is a key component for an on-chip optical phased array. In order to form a beam with a small divergence angle, WGAs of several millimeters in length are highly desired. However, in high-index-contrast platforms such as silicon-on-insulator (SOI), such long WGAs typically require weakly modulated gratings with critical feature sizes below 10 nm. In this paper, we experimentally demonstrate a new, to the best of our knowledge, strategy to implement long WGAs. Instead of directly modulating a waveguide, we propose periodically modulating the evanescent field with subwavelength blocks. With this arrangement, weak grating strength can be achieved while maintaining a minimum feature size as large as 100 nm. For proof-of-concept, we experimentally demonstrate a 1-mm-long, single-etched WGA on a conventional 220 nm SOI platform, which achieves a far-field divergence angle of 0.095° and a wavelength scanning sensitivity of 0.168°/nm.

Procédé de greffes enfouies en situation d’échecs d’autogreffes cutanées

Local conditions can lead to a failure of traditional skin grafts. We propose here our technique about the realization of autologous skin graft using it buried chipped grafts, for wounds in failure of treatments or at risk of failure. The protocol includes cutting the skin graft within little squared pieces of a few millimeters of length, that are then buried directly deep into the wound. We can then obtain little islands of epidermisation on the random places of the wound that will heal by confluence of those epidermal islands.

On constriction and striation of a diffuse DBD in large gap filled with moderate pressure helium diluted by the air and easily ionized impurity

The experimental results on studying the plane-to-plane dielectric barrier discharge (DBD) excited in a very large volume (120 × 120 × 120 mm3) are presented. The DBD was powered by sinusoidal voltage with a frequency of 100 kHz. The plasma-forming gas is helium, which is slightly diluted by the air and trace impurity of an easily ionized gas. The total pressure of the working gas was varied within of 20–100 Torr. A moderate gas pressure allowed one the creation of non-typical DBD with a very long plasma column of 12 cm in length. Such a long gap DBD exhibits new features in its behavior compared to the well-known DBD in short gaps of several millimeters in length. Immediately after the discharge ignition, a long and uniform diffuse plasma column occurs that occupies the entire space of the inter-electrode bulk. However, this transversally homogeneous plasma mode is unstable. The ionization-thermal instability develops in the plasma owing to gas heating by the discharge. Therefore, the transversally uniform plasma breaks into several separate narrow current channels that move chaotically relative to each other. After a while, they eventually integrate into a single constricted plasma column located in the center part of the discharge volume. At the very beginning of its formation, the constricted plasma column is longitudinally uniform. But soon, it becomes streated. The strata are almost standing and their shape differs from that in a DC glow discharge at low pressure in a sealed tube. The revealed features in the slow spatial-temporal behavior of the long gap DBD are discussed with the involvement of mathematical analysis describing the small plasma disturbance development in the linear approximation.

Microstructural evolution of lamellar Fe-25Ni foams during steam-hydrogen redox cycling

Cyclical steam oxidation and hydrogen reduction, relevant to iron-air batteries, is performed on freeze-cast Fe-25Ni (at.%) foams consisting of colonies of parallel lamellae separated by channels, both ∼20 µm thick and millimeters in length. This structure is designed to accommodate volumetric changes associated with the cyclical oxidation and reduction of Fe. Metallographic imaging performed at various redox stages, together with time-resolved in situ X-ray diffraction during redox cycling, detail the reaction kinetics and phase evolution of the foam, the evolution of its lamellar microstructure, and the eventual degradation of its internal architecture. As Fe preferentially oxidizes over Ni, each lamella develops an outer Fe-oxide scale, with metallic Ni rejected to the cores of the lamellae which develops an interconnected network of Fe-oxide veins. The Ni-rich metallic core limits the accumulation of Kirkendall pores and provides adhesion to the Fe-oxide scale, thus preventing lamellar fracture observed in unalloyed Fe foams. While the oxidation rate is slowed by the presence of Ni, the reduction rate is accelerated, as Ni acts as a catalyst and as the network of oxidized veins reduces quickly and become open microchannels, thereby providing rapid hydrogen access (driving reduction) and steam egress to the lamellar interior. After complete reduction, the Fe-rich shell and the Ni-rich core interdiffuse and homogenize, which helps eliminate both Kirkendall pores and microchannels from the lamellae. Furthermore, the ductile Ni-rich core limits lamellar buckling (another densification mechanism active in Fe foams). Architectural changes also affect resistance to internal damage, with smaller lamellar colonies exhibiting better resistance to buckling. These combined effects provided by Ni alloying allow the Fe-25Ni foams to maintain a high channel porosity (>40% porous), and thus high active surface area, after 10 redox cycles, as compared to a near complete loss of open channel porosity reported in unalloyed Fe foams.