Oxygen Diffusion Research Articles

Enhanced reactivity over Ce2(SO4)3/MgO with NiO modification for chemical looping partial oxidation of methane

Chemical looping partial oxidation of methane to syngas is a promising process. Thermodynamic and kinetic analysis both forecast the NiO/Ce2(SO4)3–MgO is a prospective oxygen carrier (OC) to this process, which enables with 100% syngas selectivity, 2.15H2/CO ratio, excellent methane conversion and stable cycling characteristic. Compared with Ce2(SO4)3, the methane conversion rate rise by 73.19% because of the excellent lattice oxygen availability, less carbon deposit, and large specific surface area. The distinctive pore structure also provides a favorable reaction environment. Through the density functional theory, Ni doping can lower the energy barrier (Eb), promote lattice oxygen activation and diffusion, and the oxygen vacancy (Ov) can further promote these processes. CH3 → CH2 + H (TS2) is the rate-limiting step. Compared with Ce2(SO4)3, the Ni doping can reduce Eb by 16.8%, and the Ov can further reduce it by 43.0%. It does not change when the Ov concentration is more than 1.96%.

Hierarchical pore engineering of MOF-5 derived electrocatalysts with high mass transfer for zinc-air flow batteries

From micro to macro level, the performance of zinc-air flow battery (ZAFB) hinges on two crucial factors: the effective oxygen reduction reaction (ORR) electrocatalysts, and the durable triple-phase electrodes. However, sluggish kinetic process always occurs due to insufficient active sites and hysteretic mass transfer. In this work, a well-confined iron phthalocyanine (FePc) structure onto carbonized metal-organic framework (C-MOF5) electrocatalyst is constructed through a pyrolysis-free strategy. The macrocyclic skeleton of MOF-5 has been confirmed to offer a stronger and more abundant environment for hosting FePc molecules. Attributing to the hierarchical pore engineering of MOF-5, the FePc@C-MOF5 electrocatalyst reveals a high content of Fe (5.68 wt%) with multiple exposed active sites. Notably, the FePc@C-MOF5 exhibits a remarkably high half-wave potential of 0.915 V for ORR in 0.1 M KOH, surpassing that of commercial Pt/C by nearly 60 mV. From a higher-level device perspective, the highest oxygen diffusion velocity and local current density of the FePc@C-MOF5 electrode is verified by computational fluid dynamics (CFD) simulations. As a result, the as-assembled ZAFB demonstrates long-term stability with 200 h’ cycling. This work not only presents the hierarchical pore tailoring strategy for designing ORR electrocatalysts but also offers a deeper understanding of the essence of interfacial mass transfer.

A device for rapid calorimetric measurements on small biological tissue samples

AbstractA new calorimetric technique is described that allows high-throughput heat production rate measurements on small biological tissue samples. The technique is based on the widely used thermopile chip technology combined with an innovative method for precise transport and positioning of samples of different biological materials at the thermal power detector inside the calorimeter. The new transport and positioning technique is a combination of fluidic and mechanical transport, where the latter is realized by a magneto-motor drive. The transport facility ensures good diffusive oxygen penetration into the sample, which is essential for highly metabolically active materials. The proper functioning of the device is demonstrated by measuring the heat production of metabolically active brown adipose tissue, biopsied tegu lizard muscle, and live Drosophila larvae at different stages and temperatures.

How quickly does FLASH need to be delivered? A theoretical study of radiolytic oxygen depletion kinetics in tissues

Purpose. Radiation delivered over ultra-short timescales (‘FLASH’ radiotherapy) leads to a reduction in normal tissue toxicities for a range of tissues in the preclinical setting. Experiments have shown this reduction occurs for total delivery times less than a ‘critical’ time that varies by two orders of magnitude between brain (∼0.3 s) and skin (⪆10 s), and three orders of magnitude across different bowel experiments, from ∼0.01 to ⪆(1–10) s. Understanding the factors responsible for this broad variation may be important for translation of FLASH into the clinic and understanding the mechanisms behind FLASH. Methods. Assuming radiolytic oxygen depletion (ROD) to be the primary driver of FLASH effects, oxygen diffusion, consumption, and ROD were evaluated numerically for simulated tissues with pseudorandom vasculatures for a range of radiation delivery times, capillary densities, and oxygen consumption rates (OCR’s). The resulting time-dependent oxygen partial pressure distribution histograms were used to estimate cell survival in these tissues using the linear quadratic model, modified to incorporate oxygen-enhancement ratio effects. Results. Independent of the capillary density, there was a substantial increase in predicted cell survival when the total delivery time was less than the capillary oxygen tension (mmHg) divided by the OCR (expressed in units of mmHg/s), setting the critical delivery time for FLASH in simulated tissues. Using literature OCR values for different normal tissues, the predicted range of critical delivery times agreed well with experimental values for skin and brain and, modifying our model to allow for fluctuating perfusion, bowel. Conclusions. The broad three-orders-of-magnitude variation in critical irradiation delivery times observed in in vivo preclinical experiments can be accounted for by the ROD hypothesis and differences in the OCR amongst simulated normal tissues. Characterization of these may help guide future experiments and open the door to optimized tissue-specific clinical protocols.

Mesoporous Pdx-Nix aerogels for electrocatalytic evaluation of urea-assisted electrolysis

AbstractThis work presents the synthesis and evaluation of Pd-Ni aerogels toward the urea oxidation reaction (UOR). The incorporation of Ni led to a 0.13 V reduction in the energy required for the oxidation and reduction of PdO compared to monometallic Pd, both in alkaline medium with and without urea. Varying the Ni ratios in Pd (Pd-Ni 4:1, Pd-Ni 1:1, and Pd-Ni 1:4) led to significant changes in the electrochemical behaviour. In alkaline medium without urea, PdNi 4:1 showed the formation of NiOOH at 1.35 V, which promoted oxygen diffusion on the electrode surface and increased the current density, confirming the increase in the active sites of NiOOH and NiPdOOH and enabling urea-based electrolysis at these sites. While palladium aerogels alone are ineffective for UOR, the presence of nickel plays a key role in enhancing the UOR efficiency. On the other hand, physicochemical characterisation revealed that PdNi 4:1 has a crystal size of 4.37 nm and a larger shift in the 2θ positions of the (111) and (200) planes, which favours electronic changes that were investigated by XPS. These changes affected the electrocatalytic activity, which is primarily related to electronic effects. The results of SEM and TEM studies and nitrogen adsorption-desorption isotherm confirmed that the aerogels are highly porous and have an effective surface area and abundant active sites for reactions that allow efficient mass transfer and low diffusion resistance. TEM observations revealed interconnected nanochains indicating optimal electrocatalytic activity for both ORR and UOR due to high mass transfer. These interconnected networks are crucial for improving electrocatalytic activity in the urea oxidation reaction.

High-temperature oxidation characteristics of 20CrMnTi electroplated with copper

During high-temperature forming and phase change heat treatment, the steel surface is susceptible to oxidation. This can negatively affect the surface quality of steel parts. The production of antioxidant coatings on the surface of steel parts is important for high-temperature precision forming and heat treatment. In this paper, the high-temperature oxidation tests of 20CrMnTi steel, copper, and 20CrMnTi electroplated with copper are conducted. The 20CrMnTi samples showed varying degrees of mass gain above 900 °C; the copper samples showed varying degrees of mass gain above 700 °C; and the process of mass gain for copper-plated 20CrMnTi followed the same trend as for copper during heating and holding. For heated samples of 20CrMnTi plated with copper, the copper coating was oxidized and residual copper was observed in the oxide layer. The distance between the residual copper and the surface of the sample is greater than between the residual copper and the junction of the plating layer and the substrate. Oxygen diffuses through internal defects in the material at a higher rate than copper oxidation. In this study, an oxygen diffusion model and an antioxidant protective layer model at high temperatures were suggested. The protective layer against oxidation recommended in this research is a dense coating consisting of single crystals or fine grains free of porosities and cracks.

Use of Perfluorochemicals in Li-Air Batteries: A Critical Review.

As lithium-ion (Li-ion) batteries approach their theoretical limits, alternative energy storage systems that can power technology with greater energy demands must be realized. Li-metal batteries, particularly Li-air batteries (LABs), are considered a promising energy storage candidate due to their inherent lightweight and energy-dense properties. Unfortunately, LAB practicality remains hindered by inadequate oxygen solubility and diffusion rates within the electrolyte, both which are fundamental for LAB operation. Due to exceptionally high oxygen solubilities, perfluorochemicals (PFCs) have been investigated as a promising solution to this issue. Although PFCs have been reported to enhance LAB performance and longevity when implemented within the cathodic regions of LABs in several studies, the influence of this class of compounds on other components of the battery (including the anode and the electrolyte) is also highly important. This paper reviews the use of PFCs in LABs to date and discusses the performance enhancements resulting from their implementation. We identify and discuss future prospects and emerging research directions for the use of PFCs into LAB design, in the effort toward realization of high-performing LAB technologies.

A pore scale model study of mass transfer and electrochemical reaction in cathode catalytic layer of high-temperature polymer electrolyte membrane fuel cells

The mass transfer and related electrochemical reactions in the catalytic layer (CL) are crucial for the performance of high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs), but there is a lack of understanding of the optimal phosphoric acid content and Pt/C catalyst loading in the CL. In this work, we investigate the influences of Pt/C catalyst numbers (NPt/C) and phosphoric acid film thickness (δPA) on mass transfer and electrochemical reactions of the cathode CL using a pore-scale model (300 × 300 × 300 nm3). The results reveal that larger NPt/C and δPA can impede oxygen diffusion, while lower NPt/C and δPA lead to fewer reaction active sites and lower conductivity, both of which result in lower current density. Therefore, the balance of three-phase transport is extremely important for CL. There is a 3D volcanic relationship between current density, Pt/C catalysts, and phosphoric acid film. At NPt/C = 200 (7407 per μm3) and δPA = 4 nm (the volume fractions of 37.22 % and 17.87 %), the highest current density can be achieved at a potential of 0.5 V (vs. RHE), which increased with the decrease of potential. This work is valuable for understanding the optimizing the microstructure and three-phase transport pathway of the CL to improve the performance of HT-PEMFCs.

Exposure to fine particulate matter 2.5 from wood combustion smoke causes vascular changes in placenta and reduce fetal size

During gestation, maternal blood flow to the umbilical cord and placenta increases, facilitating efficient nutrient absorption, waste elimination, and effective gas exchange for the developing fetus. However, the effects of exposure to wood smoke during this period on these processes are unknown. We hypothesize that exposure to PM2.5, primarily sourced from wood combustion for home heating, affects placental vascular morphophysiology and fetal size. We used exposure chambers that received either filtered or unfiltered air. Female rats were exposed to PM2.5 during pre-gestational and/or gestational stages. Twenty-one days post-fertilization, placentas were collected via cesarean section. In these placentas, oxygen diffusion capacity was measured, and the expression of angiogenic factors was analyzed using qPCR and immunohistochemistry. In groups exposed to PM2.5 during pre-gestational and/or gestational stages, a decrease in fetal weight, crown-rump length, theoretical and specific diffusion capacity, and an increase in HIF-1α expression were observed. In groups exposed exclusively to PM2.5 during the pre-gestational stage, there was an increase in the expression of placental genes Flt-1, Kdr, and PIGF. Additionally, in the placental labyrinth region, the expression of angiogenic factors was elevated. Changes in angiogenesis and angiogenic factors reflect adaptations to hypoxia, impacting fetal growth and oxygen supply. In conclusion, this study demonstrates that exposure to PM2.5, emitted from wood smoke, in both pre-gestational and gestational stages, affects fetal development and placental health. This underscores the importance of addressing air pollution in areas with high levels of wood smoke, which poses a significant health risk to pregnant women and their fetuses.

LAMA improve tissue oxygenation more than LABA in patients with COPD

Background The effect of bronchodilators is mainly assessed with forced expiratory volume in 1s (FEV1) in COPD. Their impact on oxygenation and lung periphery is less known. Objectives To compare the action of long-acting ß2-agonists (LABA-olodaterol) and muscarinic antagonists (LAMA-tiotropium) on tissue oxygenation in COPD, considering their impact on proximal and peripheral ventilation as well as lung perfusion. Methods FEV1, Helium slope (SHe) from a single-breath washout test (SHe decrease reflecting a peripheral ventilation improvement), frequency dependence of resistance (R5-R19), area under reactance (AX), lung capillary blood volume (Vc) from double diffusion (DLNO/DLCO) and transcutaneous oxygenation (TcO2) were measured before and 2 hours post-LABA (day 1) and LAMA (day 3) in 30 COPD patients (FEV1 54±18% pred; GOLD A 31%/B 48%/E 21%) after 5-7 days of washout, respectively. Results TcO2 increased more (p=0.03) after LAMA (11±12%from baseline, p<0001) compared to LABA (4±11%, p=0.06) despite a lower FEV1 increase (p=0.03) and similar SHe (p=0.98), AX (p=0.63) and R5-R19 decreases (p=0.37). TcO2 and SHe changes were negatively correlated (r=-0.47, p=0.01) after LABA, not after LAMA (r=0.10, p=0.65). DLNO/DLCO decreased and Vc increased after LAMA (p=0.04; p=0.01, respectively) but not after LABA (p=0.53; p=0.24). Conclusion LAMA significantly improved tissue oxygenation in COPD patients, while only a trend was observed with LABA. The mechanisms involved may differ between both drugs: LABA increased peripheral ventilation while LAMA increased lung capillary blood volume. Should oxygenation differences persist over time, LAMA could arguably become the first therapeutic choice in COPD.

Versatile micro-electrode array to monitor human iPSC derived 3D neural tissues at air-liquid interface.

Engineered 3D neural tissues made of neurons and glial cells derived from human induced pluripotent stem cells (hiPSC) are among the most promising tools in drug discovery and neurotoxicology. They represent a cheaper, faster, and more ethical alternative to in vivo animal testing that will likely close the gap between in vitro animal models and human clinical trials. Micro-Electrode Array (MEA) technology is known to provide an assessment of compound effects on neural 2D cell cultures and acute tissue preparations by real-time, non-invasive, and long-lasting electrophysiological monitoring of spontaneous and evoked neuronal activity. Nevertheless, the use of engineered 3D neural tissues in combination with MEA biochips still involves series of constraints, such as drastically limited diffusion of oxygen and nutrients within tissues mainly due to the lack of vascularization. Therefore, 3D neural tissues are extremely sensitive to experimental conditions and require an adequately designed interface that provides optimal tissue survival conditions. A well-suited technique to overcome this issue is the combination of the Air-Liquid Interface (ALI) tissue culture method with the MEA technology. We have developed a full 3D neural tissue culture process and a data acquisition system composed of high-end electronics and novel MEA biochips based on porous, flexible, thin-film membranes integrating recording electrodes, named as "Strip-MEA," to allow the maintenance of an ALI around the 3D neural tissues. The main motivation of the porous MEA biochips development was the possibility to monitor and to study the electrical activity of 3D neural tissues under different recording configurations, (i) the Strip-MEA can be placed below a tissue, (ii) or by taking advantage of the ALI, be directly placed on top of the tissue, or finally, (iii) it can be embedded into a larger neural tissue generated by the fusion of two (or more) tissues placed on both sides of the Strip-MEA allowing the recording from its inner part. This paper presents the recording and analyses of spontaneous activity from the three positioning configurations of the Strip-MEAs. Obtained results are discussed with the perspective of developing in vitro models of brain diseases and/or impairment of neural network functioning.

Humidity impact on polarization dynamics in polymer electrolyte membrane fuel cells through distribution of relaxation times analysis

The interaction among relative humidity, current density, and internal polarization plays a crucial role in optimizing the performance of polymer electrolyte membrane fuel cells (PEMFCs). However, achieving swift analysis and feedback on the internal humidity status of PEMFCs through on-vehicle impedance spectroscopy measurements remains a significant challenge. Conducting a series of impedance spectra under operating conditions of 30 %, 50 %, and 80 % relative humidity sheds light on the impact of humidity on performance. Correlations between specific distribution of relaxation times (DRT) peaks and internal polarization are established. Through DRT analysis, four polarization dynamics related to proton transfer at the proton exchange membrane interface, proton transport in the cathode catalyst layer, charge transfer, and the oxygen diffusion process are effectively identified based on characteristic frequencies and peaks. The rate-determining step of the polarization varies under idling, rated, and overload conditions, providing valuable insights. This study contributes analytical models and strategic guidance for tailoring relative humidity conditions to mitigate polarization, thereby enabling real-time control and enhancement of PEMFC performance.

In-situ Synchrotron x-ray photoelectron spectroscopy study of medium-temperature baking of niobium for SRF application

Abstract In order to determine optimal parameters of vacuum thermal processing of superconducting radiofrequency niobium cavities exhaustive information on the initial chemical state of niobium and its modification upon a vacuum heat treatment is required. In the present work the chemical composition of the niobium surface upon ultra-high vacuum baking at 200–400 °C similar to “medium-temperature baking” and “furnace baking” of cavities is explored in-situ by synchrotron X-ray photoelectron spectroscopy (XPS). Our findings imply that below the critical thickness of the Nb2O5 layer (≈ 1 nm) niobium starts to interact actively with surface impurities, such as carbon and phosphorus. By studying the kinetics of the native oxide reduction, the activation energy and the rate-constant relation have been determined and used for the calculation of the oxygen-concentration depth profiles. It has been established that the controlled diffusion of oxygen is realized at temperatures 200–300 °C, and the native-oxide layer represents an oxygen source, while at 400 °C the pentoxide is completely reduced and the doping level is determined by an ambient oxygen partial pressure. Fluorine (F to Nb atomic ratio is 0.2) after the buffered chemical polishing was found to be incorporated into the surface layer probed by XPS (≈ 4.6 nm), and its concentration increased during the low-temperature baking (F/Nb=0.35 at 230 °C) and depleted at higher temperatures (F/Nb=0.11 at 400 °C). Thus, the influence of fluorine on the performance of mid-T baked, nitrogen-doped and particularly mild-baked (120 °C/48 h) cavities must be considered. The possible role of fluorine in the educed Nb+5 → Nb+4 reaction under the impact of an X-ray beam at room temperature and during the thermal treatment is also discussed. The range of temperature and duration parameters of the thermal treatment at which the niobium surface would not be contaminated with impurities is determined.

Poly(ionic liquid) Ionomers Help Prevent Active Site Aggregation, in Single-Site Oxygen Reduction Catalysts.

Anion exchange membrane fuel cells (AEMFCs) can produce clean electricity without the need for platinum-group metals at the cathode. To improve their durability and performance, most research investigations so far have focused on optimizing the catalyst and anion exchange membrane, while few studies have been dedicated to the effect of the ionomer. Herein, we address this gap by developing a poly(ionic liquid)-based ionomer and studying its effect on oxygen transport and oxygen reduction kinetics, in comparison to the commercial proton exchange and anion exchange ionomers Nafion and Fumion. Our study shows that the choice of ionomer has a dramatic effect on the morphology of the catalyst layer, in particular on iron aggregation. We also observed that the quality of the catalyst layer and the degree of iron aggregation can be correlated to the rheological properties of the catalyst ink. Moreover, this work highlights the impact of the ionomer on the resistance to oxygen transport and reports improved oxygen diffusion compared to Nafion, for poly(ionic liquid)s with fluorinated anions. Finally, the performance of the catalyst-ionomer layer for oxygen reduction was tested with a rotating disc electrode (RDE) and a gas diffusion electrode (GDE). We observed dramatic differences between the two configurations, which we attribute to the different morphologies of the catalyst layer. In summary, our study highlights the dramatic and overlooked effect of the ionomer and the limitations of the RDE in predicting fuel cell performance.

A Pillar/Perfusion Plate Enhances Cell Growth, Reproducibility, Throughput, and User Friendliness in Dynamic 3D Cell Culture.

Static three-dimensional (3D) cell culture has been demonstrated in ultralow attachment well plates, hanging droplet plates, and microtiter well plates with hydrogels or magnetic nanoparticles. Although it is simple, reproducible, and relatively inexpensive, thus potentially used for high-throughput screening, statically cultured 3D cells often suffer from a necrotic core due to limited nutrient and oxygen diffusion and waste removal and have a limited in vivo-like tissue structure. Here, we overcome these challenges by developing a pillar/perfusion plate platform and demonstrating high-throughput, dynamic 3D cell culture. Cell spheroids were loaded on the pillar plate with hydrogel by simple sandwiching and encapsulation and cultured dynamically in the perfusion plate on a digital rocker. Unlike traditional microfluidic devices, fast flow velocity was maintained within perfusion wells and the pillar plate was separated from the perfusion plate for cell-based assays. It was compatible with common lab equipment and allowed cell culture, testing, staining, and imaging in situ. The pillar/perfusion plate enhanced cell growth by rapid diffusion, reproducibility, assay throughput, and user friendliness in a dynamic 3D cell culture.

Structure and ionic conduction enhancement mechanisms at CeO2/SrTiO3 heterointerfaces

Fluorite-perovskite heterointerfaces garner great interest for enhanced ionic conductivity for application in electronic and energy devices. However, the origin of observed enhanced ionic conductivity as well as the details of the atomic structure at these interfaces remain elusive. Here, systematic, multi-stoichiometry computational searches and experimental investigations are performed to obtain stable and exact atomic structures of interfaces between CeO2 and SrTiO3—two archetypes of the corresponding structural families. Local reconstructions take place at the interface because of mismatched lattices. TiO2 terminated SrTiO3 causes a buckled rock salt CeO interface layer to emerge. In contrast, SrO terminated SrTiO3 maintains the fluorite structure at the interface compensated by a partially occupied anion lattice. Moderate enhancement in oxygen diffusion is found along the interface by simulations, yet evidence to support further significant enhancement is lacking. Our findings demonstrate the control of interface termination as an effective pathway to achieve desired device performance.

Tailored high-temperature corrosion behavior of Cr coatings using high power impulse magnetron sputtering on ZIRLO alloys for accident-tolerant fuel application

To further enhance the oxidation resistance of Zirconium alloys during Loss of Coolant Accident (LOCA), protective Cr coatings were deposited in synchronized pulse bias mode through high power impulse magnetron sputtering (HiPIMS). The results showed the weight gain of the Cr coatings with synchronized pulse bias was reduced by approximately 61.7 % compared to that of the Cr coatings without synchronized pulse bias after 90 min of steam oxidation at 1200 °C. This was mainly attributed to the formed intense (200) preferred orientation of the Cr coatings with synchronized pulse bias during deposition, accelerating the recrystallization growth of the residual Cr layer in a high-temperature steam environment, thereby reducing the rapid diffusion pathways for oxygen. Moreover, the synchronized pulse bias induced Cr grains refinement, favoring the formation of a more compact Cr2O3 scale, and therefore efficiently inhibiting the diffusion of external oxygen to the underlying alloy.

Modeling the phase boundaries in Cu(100)-(2√2 × √2)R45°-O missing row reconstruction (MRR) structure

Although the structure of Cu(100)-(22×2)R45°-O missing row reconstruction (MRR) has been well-established for decades, the detailed structure of its various boundaries remains an untilled area due to the difficulties in obtaining atomically resolved images. Herein, atomic arrangement of the phase boundaries existing in MRR structure was modeled on the basis of scanning tunneling microscopy (STM) investigations. By determining the periodicity and unit structure of MRR in STM images and extending them to boundary region, several types of phase boundaries were identified, resulted respectively from: (1) the mismatch between c(2 × 2)-O patches, (2) the regulation by step edges, and (3) the mismatch between Cu missing rows (MRs). With the modeled structure, it was revealed that the types of the c(2 × 2)-O mismatch induced phase boundaries (OMIPBs) are mainly dominated by the oxygen exposure and in-diffusion barrier. The step edge regulated phase boundaries (SERPBs) are always terminated with Cu-O chain and may represent an intermediate growth stage to larger MRR structure. Comparatively, Cu MRs mismatch is often reconciled by the differently oriented domains between them. As a result, the Cu MRs mismatch induced phase boundaries (CMRMIPBs) are only occasionally observed as Cu-O chains between mismatched Cu MRs that encounter shoulder-to-shoulder. For all studied boundaries, the surrounding MRR domains exhibit obvious orientation preference through inclined packing along the SP direction with the degree closely related with the width of the boundaries.

Effects of Oxygen Therapy on Patients with a Chronic Wound: A Systematic Review and Meta-analysis.

To synthesize the effects of oxygen-based therapy on patients with a chronic wound. The authors searched PubMed, EMBASE, and Cochrane Central Register of Controlled Trials for relevant randomized controlled trials from database inception. Investigators measured risk of bias using the Cochrane Collaboration's Risk of Bias tool. The included randomized controlled trials focused on the effects (short- or long-term wound healing, amputation rate, percentage of reduction in ulcer size, and poststudy transcutaneous oxygen measurement [TcPO2]) of oxygen-based therapy (including hyperbaric oxygen therapy, topical oxygen therapy, and continuous diffusion of oxygen) on patients with a chronic wound. Researchers extracted information regarding participant characteristics and primary and secondary outcomes from the included studies. Pooled effects of 31 included studies showed that patients treated with oxygen had better short-term wound healing (risk ratio [RR], 1.544; 95% CI, 1.199 to 1.987), a higher percentage reduction in the ulcer area (standardized mean difference [SMD], 0.999; 95% CI, 0.439 to 1. 599), lower amputation rates (RR, 0.529; 95% CI, 0.325 to 0.862), shorter wound healing time (SMD, -0.705; 95% CI, -0.908 to -0.501), and higher poststudy TcPO2 (SMD, 2.128; 95% CI, 0.978 to 3.278) than those in the control group. For long-term wound healing, there was no statistically significant difference (RR, 1.227; 95% CI, 0.976 to 1.542). Oxygen-based therapy improves short-term parameters of wound healing in patients with chronic wounds.

In-vitro fretting tribocorrosion and biocompatibility aspects of laser shock peened Ti-6Al-4V surfaces

Laser shock peening without coating (LSPwC), a prospective surface modification technique for improving the mechanical aspects of Ti-6Al-4V alloy for automotive/aerospace sector, is also expected to dictate the efficiency of this material class for implant application. Here we unravel the impact of LSPwC on Ti-6Al-4V material surface characteristics, in-vitro tribocorrosion and biocompatibility. Micrography show the presence of nano and sub-micron sized pore after LSPwC process. The role of nano and sub-micron sized pores along with topography modification induced by LSPwC to serve as cues for controlling gene expressions, cell adhesion and activities offer novel insights in this research direction. A detailed X-ray photoelectron spectroscopy analysis detected local chemical non-stoichiometry with reduced number of oxygen diffusion channels. A crucial outcome of this oxide layer modification is the negative skewness (−0.55 ± 0.11) and reduced kurtosis (3.49 ± 0.14) of the surface, along with localized plastic deformation. These factors are correlated with the shift in potential during fretting tribo-corrosion from −800 to −250 mV after LSPwC, accompanied by a lower coefficient of friction of 0.4. Furthermore, the presence of well-spread cells and the up-regulation of beneficial genetic markers (Ki67) on LSPwC surfaces have the potential to form a better bone-material interface. The findings open new frontiers of the LSPwC-treated Ti-6Al-4V surface to synergistically modulate the tribocorrosion and biocompatibility aspects, with exciting possibilities for biomedical implants.