Search Results (246)

Hydrogen sulfide (H₂S) can be produced from the metabolism of foods containing sulfur in the gastrointestinal tract (GIT). At low doses, H₂S regulates the gut microbial community and supports GIT health, but depending on dose, age, and individual health conditions, it may also contribute to inflammatory responses and gut barrier dysfunction. Controlling H₂S production in the GIT is important for maintaining a healthy gut microbiome. However, research on this subject is limited due to the gaseous nature of the chemical and the difficulty of accessing the GIT in situ. In the present ex vivo experiment, we used a single-dose sodium sulfide preparation (SSP) as a H₂S precursor to test the effect of H₂S on the human gut microbiome across different age groups, including breastfed infants, toddlers, adults, and older adults. Metagenomic sequencing and metabolite measurements revealed that the development of the gut microbial community and the production of short-chain fatty-acids (SCFAs) were age-dependent; that the infant and the older adult groups were more sensitive to SSP exposure; that exogeneous SSP suppressed SCFA production across all age groups, except for butyrate in the older adult group, suggesting that H₂S selectively favors specific gut microbial processes. Full article

An efficient in vitro propagation protocol for Eulophia bicallosa was developed using asymbiotic seed germination and protocorm proliferation. The effect of light on seed germination and development was evaluated on Vacin and Went (VW) medium under five conditions: darkness, white, green, red, and blue light for 24 weeks. Blue and red light significantly accelerated seed development, allowing progression to stage 5 within 24 weeks. For protocorm proliferation, six semi-solid culture media were tested. Half-strength Murashige and Skoog (½MS) medium yielded the best results after 8 weeks, producing the highest numbers of shoots (1.0), leaves (1.1), and roots (4.2) per protocorm, with 100% survival. The effects of organic additives were also evaluated using coconut water and potato extract. A combination of 200 mL L⁻¹ coconut water and 50 g L⁻¹ potato extract enhanced shoot formation (1.7 shoots), while 150 mL L⁻¹ coconut water with 50 g L⁻¹ potato extract increased both leaf (1.9) and root (8.8) numbers. The effects of cytokinins (benzyladenine (BA), kinetin (6-furfurylaminopurine), and thidiazuron (TDZ)) and auxins (indole-3-acetic acid (IAA), α-naphthalene acetic acid (NAA), indole-3-butyric acid (IBA), and 2,4-dichlorophenoxyacetic acid (2,4-D)) were investigated using ½MS medium supplemented with each plant growth regulator individually at concentrations of 0, 0.1, 0.5, 1.0, and 2.0 mg L⁻¹. Among the cytokinins, 0.1 mg L⁻¹ BA produced the highest survival rate (96%), while 1.0 mg L⁻¹ BA induced the greatest shoot formation (93%, 2.3 shoots). Among the auxins, 0.1 mg L⁻¹ IAA resulted in the highest survival (96%), and 1.0 mg L⁻¹ IAA significantly enhanced root induction (4.2 roots per protocorm). Acclimatization in pots containing a 1:1:1 (v/v) mixture of pumice, sand, and soil resulted in 100% survival. This protocol provides a reliable and effective approach for the mass propagation and ex situ conservation of E. bicallosa. Full article

Laboratory data from in-cell tests at and near open circuit potentials (OCV) and ex-situ H₂O₂ vapor exposure tests are used to develop a fluoride emission rate (FER) model for a state-of-the-art 12-µm thin, low equivalent weight, long-chain perfluorosulfonic acid (PFSA) ionomer membrane that is mechanically reinforced with expanded PTFE and chemically stabilized with 2 mol% cerium as an anti-oxidant. The anode FER at OCV linearly correlates with O₂ crossover from the cathode and the high yield of H₂O₂ at anode potentials, as observed in rotating ring disk electrode (RRDE) studies. The cathode FER may be linked to the energetic formation of reactive hydroxyl radicals (·OH) from the decomposition of H₂O₂ produced as an intermediate in the two-electron ORR pathway at high cathode potentials. Both anode and cathode FERs are significantly enhanced at low relative humidity and high temperatures. The modeled FER is strongly influenced by the gradients in water activity and cerium concentration that develops in operating fuel cells. Membrane stability maps are constructed to illustrate the relationship between the cell voltage, temperature, and relative humidity for FER thresholds that define H₂ crossover failure by chemical degradation over a specified lifetime. Full article

Prussian blue and its analogs (PBAs), considered potential cathode materials for sodium-ion batteries (SIBs), still confront multiple challenges. For example, many defect vacancies and high crystal water content are generated during the fast crystallization of PBAs, impairing the rate performance. The stress accumulation during Na⁺ insertion/extraction destabilizes the lattice framework and then damages the electrochemical performance. Herein, iron-based Prussian blue with an open-pore skeleton structure (PB-3) is prepared using a facile template method which employs PVP and sodium citrate to control the crystallization rate and adjust the particle morphology. The prepared materials exhibit excellent kinetic properties and are conducive to mitigate the volume changes during ion insertion/extraction processes. PB-3 electrode not only exhibits a superior rate performance (92 mAh g⁻¹ reversible capacity at 2000 mA g⁻¹), but also presents superior cycling performance (capacity retention remained at 90.2% after 600 cycles at a current density of 500 mA g⁻¹). The highly reversible sodium ion insertion/extraction mechanism of PB-3 is investigated by ex situ XRD tests, which proves that the stabilized lattice structure can enhance the long cycling performance. In addition, the considerable capacitance contributes to the rate performance. This study provides valuable insights for the subsequent development of high-performance and stable cathodes for SIBs. Full article

Background/Objectives: Challenges in normothermic machine perfusion (NMP) remain, particularly concerning the duration for which individual organs can be safely preserved. We hypothesize that optimal preservation can be achieved by perfusing organs together in a multivisceral block. Therefore, our aim was to establish a platform for ex situ multivisceral organ perfusion. Methods: Multivisceral grafts containing the liver, kidneys, pancreas, spleen, and intestine were obtained from Yorkshire pigs. Three generation (gen) set-ups were tested during the iterative design process, and minor changes were made throughout. Gen 1 (n = 4) used a custom-designed single perfusion circuit. Gen 2 (n = 3) employed a dual perfusion circuit. Gen 3 (n = 4) featured a single perfusion circuit with an optimized basin and reservoir. Grafts underwent NMP using an autologous blood-based perfusate, while hemostatic parameters and function were assessed. Results: Comparing Gen 1 versus Gen 3, the mean aortic flow improved (1.018 vs. 2.089 L), resistance decreased (0.224 vs. 0.038), urine output increased (51.90 vs. 271.3 mL), oxygen consumption rose (43.56 vs. 49.52 mL O₂/min), perfusate lactate levels dropped (10.44 vs. 3.10 mmol/L), and the pH became more physiological (7.27 vs. 7.30). Cellular injury trended lower in Gen 3. Histological evaluation demonstrated minimal differences in Gens 2 and 3. Conclusions: We demonstrate the feasibility of abdominal multivisceral NMP for up to 8 h. Adequate arterial flow, stable perfusate pH, and high oxygen consumption in setup 3 indicated organ viability. Multivisceral perfusion may serve as a plat-form for long-term NMP. Full article

Objective: This ex vivo study aimed to evaluate the influence of different acquisition protocols, combining voxel size and field of view (FOV), across four cone-beam computed tomography (CBCT) systems, on the accuracy of alveolar bone level measurements for periodontal assessment. Materials and Methods: A dry human mandible was used, with standardized radiopaque markers placed on the cementoenamel junction (CEJ) of the buccal–mesial and buccal–distal aspects of teeth 34 and 43. CBCT scans were performed using four systems—Veraview^® X800, OP300 Pro^®, I-CAT Next Generation^®, and Orthophos XG^®—applying various combinations of field of view (FOV) and voxel resolution available in each device. Reference measurements were obtained in situ using a digital caliper. CBCT images were exported in DICOM format and analyzed with OnDemand3D software (version 4.6) to obtain paracoronal sections. Linear measurements from the CEJ to the alveolar crest were recorded in triplicate and compared to the gold standard using ANOVA and the Dunnett test (α = 0.05). Results: Protocols with smaller voxel sizes and limited FOVs generally yielded measurements closer to the gold standard. However, some larger-FOV protocols with intermediate voxel sizes also achieved comparable accuracy. Among the systems, the I-CAT showed lower agreement within in situ measurements, while others demonstrated reliable performance depending on the acquisition parameters. Conclusions: The findings suggest that CBCT protocols with smaller voxel sizes and reduced FOVs can enhance measurement accuracy in periodontal bone assessments. Nevertheless, intermediate protocols may offer a balance between diagnostic quality and radiation exposure, aligning with the ALADA principle. This study reinforces the need for standardized acquisition parameters tailored to periodontal imaging. Full article

Background/Objectives: Oral squamous cell carcinoma (OSCC) is the most common oral cancer, progressing from hyperplasia to dysplasia, carcinoma in situ (CIS), and finally invasive squamous cell carcinoma (ISCC). Developing an animal model that mimics both early and advanced OSCC stages has been challenging. The 4-Nitroquinoline 1-oxide (4NQO) model is considered one of the most suitable, as it represents all stages of OSCC. Nevertheless, thoroughly understanding the properties of the 4NQO model is essential for preclinical testing of novel therapeutics. Methods: We aimed to characterize the 4NQO rat model using two application methods—drinking water and topical application—over eight months. Monthly sacrifices allowed histopathological analysis and ex vivo magnetic resonance imaging (MRI) to track tumor progression. Results: CIS was observed at three months in the drinking water group, evolving into ISCC by six months, while topical application induced CIS at eight months without ISCC formation. The tongue was divided into three regions and histological properties, lesion size, and invasion depth were analyzed. In the drinking water group, particularly in the body of the tongue, we saw earlier CIS development, larger lesions, and deeper invasion. Additionally, assessment of proliferative properties showed an increased cell division in dysplastic lesions that reduced upon invasion. MRI was able to show macroscopic tumoral lesions, in concordance with histology. Conclusions: Overall, the drinking water method closely mimics human OSCC, validating the 4NQO model for translational OSCC research. Full article

Environmentally sustainable methods for producing flexible electronics, such as paper-based energy harvesters in nanogenerators, are a major objective in materials science. In this frame, the present study investigated two different Komagataeibacter sp. strains (K2G30 and K2G44), never tested as biocatalysts for the production of bacterial cellulose (BC) functionalized with iron particles to provide potential electrical conductivity. Two functionalization strategies (ex situ and in situ) were evaluated using two iron compounds FeCl₂ and FeSO₄, individually and in combination (up to 0.1% w/v), to assess efficiency and feasibility. In addition, a Design of Experiment approach was implemented to calculate quantitative mathematical models to correlate the functionalization methods with the iron amount in the BC. Among the tested conditions, BC produced by strain K2G44 using the ex situ method with FeCl₂ showed the most promising results, achieving the highest iron content (~37% atomic weight) with a highly homogeneous dispersion of iron nanoparticles. Moreover, the in situ BC functionalization using FeSO₄ led to the formation of iron gluconate. FeSO₄ alone significantly enhanced BC production in the in situ process, with yields of 2.62 ± 0.15 g/L for K2G30 and 2.05 ± 0.09 g/L for K2G44. Full article

Biomass gasification is an effective process for converting organic wastes into syngas. Syngas is a biofuel that possesses several potential applications in the energy sector. However, the major bottleneck for the commercialization of this technology is tar production in biomass gasification, which affects gasifier performance and syngas yield/quality. Tar can be destructed by adopting in situ or ex situ modes of utilizing catalysts in biomass gasification. The added advantage of tar reduction is enhanced syngas energy content. Despite their advantages, catalysts face challenges such as high costs, declining performance over time, and difficulties in regeneration and recycling. Deactivation can also occur due to poisoning, fouling, and carbon buildup. While some natural materials have been tested as alternative materials, the financial sustainability and affordability of catalysts remain crucial for large-scale syngas production. This paper offers an overview of tar reduction strategies and the role of various catalysts in the gasification process and future perspectives on catalyst development for biomass gasification. Full article

This work evaluates the effectiveness of in situ and ex situ passivation methods for mitigating the pyrophoricity of uranium–6 wt.% niobium spherical powders produced via the hydride–dehydride process coupled with plasma spheroidization. Oxide layer thickness was characterized using STEM/EDX, and pyrophoricity was assessed by a UN-recommended test method, which involves directly dropping the powders in the air. In situ passivation, performed by introducing flowing oxygen during spheroidization, produced oxide layers ranging from tens to hundreds of nanometers but resulted in inconsistent pyrophoricity mitigation at lower oxygen flow rates. Ex situ passivation, achieved by slow oxygen exposure over several months, formed uniform oxide layers of approximately 20 nm and consistently mitigated pyrophoricity. Despite requiring higher bulk oxygen content, in situ passivation enables faster processing and control of oxygen, while ex situ passivation achieves superior oxide uniformity with lower oxygen incorporation. These findings highlight the trade-offs between passivation methods and provide a foundation for improving the safety and scalability of reactive metal powder production. Full article

The resistance to erosion of stainless steel-based plasma transferred arc (PTA)-cladded hardfacings reinforced with ex-situ-synthesized TiC is compared to those reinforced using in-situ-synthesized TiC (formed from TiO₂ and graphite). The PTA cladding was performed under an optimized torch linear velocity of 0.7 m/s and cladding current of 115 A. The microstructure of the cladded overlay was analyzed using scanning electron microscopy (SEM), and the phase composition was determined using X-ray diffraction (XRD). Vickers macrohardness measurements were made at representative areas at the surface of the overlays. An erosive wear test was conducted with impact angles of 30° and 90° and impact velocities of 20, 50, and 80 m/s. The formation of TiC from TiO₂ and graphite started during ball milling and ended during the cladding stage. The final TiC content in the hardfacings was below nominal, which is likely due to carbide segregation occurring during the cladding process. The highest hardness was 2.4 times that of stainless steel, which was observed in the deposit containing 60 vol.% ex-situ-synthesized TiC. Both ex-situ and in-situ TiC reinforcement improved resistance to erosion, providing up to 1.5 times better resistance under the 30° impact angle and up to 6.3 times under the 90° impact angle than that of stainless steel. However, ex-situ TiC showed a slightly larger improvement. At the 30° impact angle, the primary wear mechanism is micro-ploughing, but at the 90° impact angle it is surface fatigue. Both mechanisms appeared at both angles under 80 m/s impact velocity. Full article

Understanding the viscoelastic properties of plantar soft tissue under dynamic conditions is crucial for assessing foot health and preventing injuries. In this work, we document an in vivo device, employing the principles of dynamic mechanical analysis (DMA), which, for the first time, enables in situ, real-time multidimensional mechanical characterization of plantar soft tissues. This device overcomes the limitations of conventional ex vivo and single-DOF testing methods by integrating three sinusoidal mechanism-based multi-DOF dynamic testing modules, providing measurements of tensile, compressive, shear, and torsional properties in a physiological setting. The innovative modular design integrates advanced sensors for precise force and displacement detection, allowing for comprehensive assessment under cyclic loading conditions. Validation tests on volunteers demonstrate the device’s reliability and highlight the significant viscoelastic characteristics of the plantar soft tissue. The example dataset was analyzed to calculate the storage modulus, loss modulus, loss factor, and energy dissipation. All design files, CAD models, and assembly instructions are made available as open-source resources, facilitating replication and further research. This work paves the way for enhanced diagnostics and personalized treatments in orthopedic and rehabilitative medicine. Full article

Passive films that form on Alloy 600 and Alloy 690 during four hours in simulated Primary Water (PW) of Pressurized Water Nuclear Reactors (PWRs) at 320 °C were investigated by in situ surface-enhanced Raman spectroscopy (SERS). Similar tests conducted on unalloyed nickel, unalloyed chromium, and laboratory alloys of Ni-10Cr, Ni-20Cr, Ni-5Cr-8Fe, and Ni-10Cr-8Fe aided in assigning the peaks in the surface-enhanced Raman (SER) spectra of the passive films of Alloy 600 and Alloy 690. SERS indicates an inner layer (IL) of Cr₂O₃/CrOOH forms on both Alloy 600 and Alloy 690 and that Alloy 690’s IL was more protective against corrosion due to its greater resistance to ion transport. The outer layer (OL) of Alloy 600 consists of NiO and spinels, FeCr₂O₄—M(Cr,Fe)₂O₄. The OL of Alloy 690 contains no spinel. A comparison of SER spectra in 320 °C PWR PW to the spectra following cooling down to room temperature and after exposure to air indicates some differences between in situ films and ex situ films. Full article

Formic acid has recently been considered one of the most promising liquid organic hydrogen carriers (LOHCs). Its decomposition to obtain H₂ has been fruitfully investigated during recent years using catalysts of a very diverse nature. Most of these catalysts lack stability, so finding stable materials under reaction conditions is highly desirable but challenging. In the present study, catalysts based on Pd nanoparticles supported on C₃N₄-modified activated carbon derived from biomass residues were developed, characterized, and assessed in the decomposition of formic acid in the liquid phase. These catalysts were prepared using a straightforward method that allowed different nitrogen contents to be achieved in the support and avoided the ex situ reduction in the Pd precursor. The results of the catalytic tests indicated the positive role of incorporating C₃N₄, leading to catalysts that displayed much better performance than the C₃N₄-free counterpart. The incorporation of C₃N₄ resulted in catalysts with small and well-distributed Pd nanoparticles, leaching resistance and modified electronic properties of the Pd species. As a result, promising catalytic activity was observed in the developed materials. Pd/AC_C₃N₄(19) attained an initial TOF of 2893 h⁻¹, and it preserved most of its catalytic activity for at least six consecutive reaction cycles, which is a remarkable characteristic of the developed catalytic system. Full article

Specklinia digitale is an epiphytic orchid endemic to Mexico. The destruction of its habitat has resulted in it being regarded as an endangered species, and, to our knowledge, no effort has been made to establish ex situ conservation programs. Here, we describe an in situ assessment of flower and fruit phenology and subsequent in vitro germination. We also established a successful protocol for asymbiotic in vitro germination and acclimatization using Murashige–Skoog (MS) medium at full (full-MS) and half (1/2 MS) strength as well as activated charcoal (AC). All-year flower and fruit production was confirmed. Nevertheless, we observed a low pollination occurrence. No significant difference in germination rate was found for the four treatments tested; however, after protocorm evaluation, full-MS plus AC emerged as the best treatment for S. digitale in vitro propagation. Germination of up to 90.53% was achieved in full-MS. The acclimatization survival was 95%. These observations and our effective germination protocol can be used in a comprehensive approach for conservation efforts of this species. Full article