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Background: Ex vivo machine perfusion (EVMP) has been established to extend viability of donor organs. However, EVMP protocols are inconsistent. We hypothesize that there is a significant relationship between specific parameters during EVMP and perfusion outcomes. Methods: A meta‐analysis of literature was conducted in accordance with the Preferred Reporting Items for Systematic Review and Meta‐Analysis (PRISMA) Statement. The search encompassed articles published before July 25, 2023. PubMed, Embase, and CENTRAL databases were screened using search terms "ex‐vivo," "ex‐situ," "machine," and "perfusion." Weight gain, an indicator of organ viability, was chosen to compare outcomes. Extracted variables included perfused organ, warm and cold ischemia time before perfusion, perfusion duration, perfusate flow, pressure, temperature, perfusate composition (presence of cellular or acellular oxygen carrier, colloids, and other supplements) and percent weight change. Data were analyzed using SPSS statistical software. Results: Overall, 44 articles were included. Red blood cell‐based perfusates resulted in significantly lower weight gain compared to acellular perfusates without oxygen carriers (11.3% vs. 27.0%, p < 0.001). Hemoglobin‐based oxygen carriers resulted in significantly lower weight gain compared to acellular perfusates (16.5% vs. 27%, p = 0.006). Normothermic perfusion led to the least weight gain (14.6%), significantly different from hypothermic (24.3%) and subnormothermic (25.0%) conditions (p < 0.001), with no significant difference between hypothermic and subnormothermic groups (24.3% vs. 25.0%, p = 0.952). There was a positive correlation between flow rate and weight gain (ß = 13.1, R = 0.390, p < 0.001). Conclusions: Oxygen carriers, low flow rates, and normothermic perfusate temperature appear to improve outcomes in EVMP. These findings offer opportunities for improving organ transplantation outcomes. [ABSTRACT FROM AUTHOR]

• A novel oxygen carrier (CuO/ZrO 2 /TiO 2 /MgO) additionally optimized. • Its performance in combustion of anthracite and bituminous investigated. • Blend of anthracite and bituminous and cyclic stability examined. • Blend (75 % anthracite + 25 % bituminous) enhanced combustion efficiency and CO 2 yield. • Novel oxygen carrier showed good reactivity and stability. Coal is the largest contributor to global CO 2 emissions, and current reserves are projected to last approximately 150 years, with 71.6 % being high-rank coals (anthracite and bituminous). Chemical looping combustion is an economical CO 2 capture method that uses oxygen carrier materials to supply oxygen for combustion. Copper is the most reactive due to its oxygen uncoupling capability, though it has poor stability. In our research, we developed a novel modified copper-based oxygen carrier with enhanced stability in oxygen uncoupling cycles by increasing the ZrO 2 ratio at the expense of TiO 2 to reduce phase interactions. The modified oxygen carrier (40 % CuO, 30 % ZrO 2 , 15 % TiO 2 , 15 % MgO) was used to combust bituminous and anthracite coal in a fixed-bed system. While bituminous coal had a high combustion rate, its efficiency was 63 %, yielding 18 mol/kg of CO 2 , compared to 90 % efficiency and 56 mol/kg CO 2 for anthracite. The lower efficiency for bituminous was due to the rapid release of volatiles. Adding steam improved bituminous combustion efficiency to 75 % and CO 2 yield to 21 mol/kg, with no significant change for anthracite. A blend of 25 % bituminous and 75 % anthracite showed better combustion efficiency, rate, and CO 2 yield. This blend test was stable over 10 cycles, as confirmed by SEM, XRD, and BET analyses. [ABSTRACT FROM AUTHOR]

This study proposed an innovative process of biomass torrefied liquids washing, torrefaction, and chemical looping gasification (BW/T-CLG). The fixed-bed reactor and Py-GC/MS were used to assess the effects of combined pretreatments on CLG performance of rice straw (RS). The pretreatment results indicate that torrefaction liquids washing effectively removed ash component in the RS, and combined measures clearly enhanced the calorific values and energy density of RS. The jointly pretreated RS exhibits good cyclic stability in multiple chemical looping gasification (CLG) cycles. When the reaction temperature boosted from 700 to 900 °C, a 34 % improvement in carbon conversion efficiency (η C) and 32.9 % rise in cold gas efficiency (η G) were achieved. As the OCs proportion increased, the η C increased from 62 % to 72 %, whereas the CO selectivity (Sel CO) and the syngas content (C syngas) generally reduced, and its optimal value was determined to be 30 %. The Py-GC/MS result showed that both washing and torrefaction decreased the levels of acidic compounds while boosting the production of high-value products. • Torrefied liquids washing, torrefaction and chemical looping gasification were combined. • Torrefied liquid washing removed most of K in straw and enhanced BCLG performances. • Torrefaction enhanced fuel properties of straw, increased energy density greatly. • Combined pretreatments improved the selectivity and quality of products from BCLG. • Combined pretreatments have declined acidic substances in bio-oil and improved quality. [ABSTRACT FROM AUTHOR]

This work systematically investigated the reaction characteristics of cotton stalk pyrolysis volatiles with CuO and NiO loaded on olivine (Cu/Ni/O) aiming to produce hydrogen-rich gas. The effect of pyrolysis temperature, gasification temperature, and oxygen carrier to biomass ratio (OC/B) on tar content, gas yield, carbon conversion has been investigated. Lattice oxygen donation capability and catalytic performance of OC was evaluated by comparing the Biomass Chemical Looping Gasification (BCLG) and catalytic gasification. Furthermore, the distribution of oxygen in the pyrolysis products and the distribution of lattice oxygen in the gasification products were investigated. The results indicate that cotton stalk pyrolysis tar is mainly composed of phenolic compounds. The OC can not only decompose most of cyclic compounds but also further reduce the content of monocyclic compounds to hydrogen-rich gas. The release of lattice oxygen from Cu/Ni/O was 56.2 %, which decreased to 47.7 % when steam was introduced at 800 °C. A H 2 concentration of 50.4 % and a H 2 yield of 0.57 Nm3/kg were achieved by both the reaction of tar reforming and the reaction of steam with reduced Fe in Cu/Ni/O. These findings offer new insights and a theoretical foundation for a detailed understanding of the BCLG. [Display omitted] • The interaction between biomass pyrolysis volatiles and oxygen carrier is systematically investigated. • The impact of the oxidation and reduction state of the Cu/Ni/O on BCLG is evaluated. • A total gas yield of 1.23 Nm3/kg and a H 2 yield of 0.57 Nm3/kg were achieved by both the reaction of tar reforming and steam with reduced Fe in Cu/Ni/O. • A tar yield of 4.41 g/Nm3 and a carbon conversion of 96.02 % were obtained. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydrogen and oxygen passivation in 4H-SiC markedly stabilizes the formation of vacancies, modifies the charge states of vacancies and regulates the doping types. • The evolution of charge transitions of vacancies in 4H-SiC altered by the passivation of hydrogen and oxygen was revealed. • The mechanism of carrier capture altered by passivations was described by the distribution of single-particle energy levels at different charge states. Unintentional dopants, such as hydrogen and oxygen, are unavoidable in the epitaxial growth of semiconductors, significantly impacting the device performances by acting as traps for interstitials and passivation. Herein, hybrid functional was adopted to systematically investigate the charge transfer of vacancies altered by hydrogen and oxygen passivation in 4H-SiC. Overall, both of them stabilize the formation of vacancies to prevent the diffusion and recombination effectively. Especially, the more the hydrogen passivated, the lower the formation energies. The number of passivated hydrogens shows huge impacts on the hole capturing of carbide vacancy (V C), while the effect is small on carbon dangling bonds to capture electron both k and h site, of which the transition level ε (0/−1) always locates around E C − 0.3–0.6 eV. Silicon vacancy (V Si) primarily acts as an electron acceptor, with its transition level ε (0/−1) showing limited response to hydrogen passivation, while the effectiveness of electron capture is determined by the passivation process. Comparing divacancy (V C V Si) with single V C and V Si , there is an enhanced ability for hole capturing by silicon dangling orbitals. Once all dangling bonds are passivated, V C , V Si and V C V Si always keep neutral state. For oxygen passivation, V C turns to a donor with one oxygen passivation and a neutral defect with fully passivated. V Si is regulated from an acceptor to a bipolar dopant with one and two oxygen passivation. Our calculations unveil the underlying mechanism for hydrogen and oxygen passivation effects on the process of carrier captures of vacancies, which can further explain the relative defect signal in experimental characterizations. [ABSTRACT FROM AUTHOR]

Chemical looping methane reforming has emerged as a promising avenue to produce blue hydrogen. Currently, satisfactory CH 4 conversion and H 2 productivity typically requires reaction temperature above 800 °C, bringing challenges for industrial reactor design and energy conservation. To realize high chemical looping methane reforming performance at low temperature, a Fe-Ni bimetallic nano oxygen carrier was presented, along with the workflow and platform for scaled-up synthesis of the oxygen carrier. On account of the synergy of nanoscale Fe-Ni species, the operating temperature could be lowered to 500–600 °C. The lab-scale oxygen carrier converted >90 % CH 4 and produced 3.5 H 2 per CH 4 molecule with 80–82 % outlet H 2 purity at 575–600 °C. The 10-kg scale synthesized oxygen carrier powder exhibited >90 % CH 4 conversion, >78 % H 2 purity and produced 2.8–3.5 H 2 per CH 4 , with performance penalty from scaling up controlled within 5 %. After shaping and calcination, the 10-kg oxygen carrier beads still produced 2.8 H 2 from per CH 4 molecule with >70 % H 2 purity. Longevity test revealed the 10-kg powder and beads as stable in phase, morphology, and redox activity over 110 cycles. Experiments of variable operating conditions found that the 10-kg oxygen carriers can meet industrial requirements of H 2 production at >550 °C, with low steam/carbon ratio favored by 10-kg beads. Further analysis attributed the performance distinction of 10-kg beads to its lower surface area, reduction extent and steam affinity, compared to those of the lab-scale and 10-kg powders. These findings contributed to the mid-temperature chemical looping methane reforming by bridging laboratory practices and industrial application. • Synthesized from lab to 10-kg scale Fe-Ni nano oxygen carrier for <600 °C reaction. • Achieved >90 % CH 4 conversion, >78 % H 2 purity and 2.8–3.5 H 2 produced per CH 4. • Performance penalty <5 % for 10-kg powder and mechanism revealed for beads. • Stable structure and reactivity of 10-kg scale powder and beads over 110 cycles. [ABSTRACT FROM AUTHOR]

Hydrogen is a clean and sustainable energy source with the potential to meet rising energy demands and address environmental concerns. Chemical looping steam CH 4 reforming is a promising technology for hydrogen production but is often restricted by the low activity and carbon deposition of oxygen carriers. In this study, a highly active and stable multicomponent oxygen carrier, LaFe 0.8 Co 0.15 Cu 0.05 O 3 /NiO/Silicalite-1 (LFCC/NiO/S-1), is synthesized using a mechanical mixing method. Compared with pure LFCC, the average hydrogen yield over LFCC/NiO/S-1 increases from 2.69 mmol/g to 3.52 mmol/g. Additionally, the purity of the produced hydrogen remains at 100 %, indicating better resistance to carbon deposition. For LFCC/NiO/S-1, CH 4 conversion exceeds 80 %, the syngas yield reaches 6.04 mmol/g, and the H₂/CO ratio is near the ideal value of 2.0. After multiple depletions and replenishments of lattice oxygen, elements migration between LFCC, NiO and S-1 occur, which plays a significant role in the redox process. In CH 4 conversion stage, larger amounts of Ni element migrate to the surface of LFCC. However, Ni element migrates from the perovskite to the surface of S-1 in water splitting stage. After the migration process, Ni particles are highly dispersed, which is favorable for the conversion of CH 4 and H 2 O in chemical looping. [Display omitted] • LFCC/NiO/S-1 shows enhanced reactivity for hydrogen production in CL-SMR. • 100 % H 2 purity is obtained in the water splitting step. • Migration of Cu and Ni elements crucially impacts redox process performance. • Migrated Ni and Cu elements captured by hydroxyl on S-1. • Dispersed Ni particles significantly activate CH 4 and H 2 O in reactions. [ABSTRACT FROM AUTHOR]