Mid-temperature CO2 Adsorption over Different Alkaline Sorbents Dispersed over Mesoporous Al2O3.

CO2 adsorbents comprising various alkaline sorption active phases supported on mesoporous Al2O3 were prepared. The materials were tested regarding their CO2 adsorption behavior in the mid-temperature range, i.e., around 300 °C, as well as characterized via XRD, N2 physisorption, CO2-TPD and TEM. It was found that the Na2O sorption active phase supported on Al2O3 (originated following NaNO3 impregnation) led to the highest CO2 adsorption capacity due to the presence of CO2-philic interfacial Al-O--Na+ sites, and the optimum active phase load was shown to be 12 wt % (0.22 Na/Al molar ratio). Additional adsorbents were prepared by dispersing Na2O over different metal oxide supports (ZrO2, TiO2, CeO2 and SiO2), showing an inferior performance than that of Na2O/Al2O3. The kinetics and thermodynamics of CO2 adsorption were also investigated at various temperatures, showing that CO2 adsorption over the best-performing Na2O/Al2O3 material is exothermic and follows the Avrami model, while tests under varying CO2 partial pressures revealed that the Langmuir isotherm best fits the adsorption data. Lastly, Na2O/Al2O3 was tested under multiple CO2 adsorption-desorption cycles at 300 and 500 °C, respectively. The material was found to maintain its CO2 adsorption capacity with no detrimental effects on its nanostructure, porosity and surface basic sites, thereby rendering it suitable as a reversible CO2 chemisorbent or as a support for the preparation of dual-function materials.

CO2 Physisorption over an Industrial Molecular Sieve Zeolite: An Experimental and Theoretical Approach.

The present work studies the adsorption of CO2 using a zeolitic industrial molecular sieve (IMS) with a high surface area. The effect of the CO2 feed concentration and the adsorption temperature in conjunction with multiple adsorption-desorption cycles was experimentally investigated. To assess the validity of the experimental results, theoretical calculations based on well-established equations were employed and the values of equilibrium, kinetic, and thermodynamic parameters are presented. Three additional column kinetic models were applied to the data obtained experimentally, in order to predict the breakthrough curves and thus facilitate process design. Results showed a negative correlation between temperature and adsorption capacity, indicating that physical adsorption takes place. Theoretical calculations revealed that the Langmuir isotherm, the Bangham kinetic model (i.e., pore diffusion is the rate-determining step), and the Thomas and Yoon-Nelson models were suitable to describe the CO2 adsorption process by the IMS. The IMS adsorbent material maintained its high CO2 adsorption capacity (>200 mg g-1) after multiple adsorption-desorption cycles, showing excellent regenerability and requiring only a mild desorption treatment (200 °C for 15 min) for regeneration.

Different reactor configurations for enhancement of CO2 methanation.

Greenhouse gas emissions are a massive concern for scientists to minimize the effect of global warming in the environment. In this study, packed bed, coated wall, and membrane reactors were investigated using three novel nickel catalysts for the methanation of CO2. CFD modelling methodologies were implemented to develop 2D models. The validity of the model was investigated in a previous study where experimental and simulated results in a packed bed reactor were in a good agreement. It was observed that the coated wall reactor had poorer performance compared to the packed bed, approximately 30% difference between the results, as the residence time of the former was lower. In addition, two membrane configurations were proposed, including a membrane packed bed and membrane coated wall reactor. Additional studies were performed in the coated wall reactor revealing that lower flow rates lead to higher conversion values. As for the bed thickness the optimum layer was found to be 1 mm. In both membrane reactor configurations, the effect of the thickness of M1 membrane, which indicates the membrane for the removal of H2O, didn't show difference while the reduction of the thickness of M2 membrane, which indicates the membrane for the removal of CO2, H2 and H2O, showed better results in terms of conversion.

Nanoparticle Exsolution from Nanoporous Perovskites for Highly Active and Stable Catalysts.

Nanoporosity is clearly beneficial for the performance of heterogeneous catalysts. Although exsolution is a modern method to design innovative catalysts, thus far it is predominantly studied for sintered matrices. A quantitative description of the exsolution of Ni nanoparticles from nanoporous perovskite oxides and their effective application in the biogas dry reforming is here presented. The exsolution process is studied between 500 and 900 °C in nanoporous and sintered La0.52 Sr0.28 Ti0.94 Ni0.06 O3±Î´ . Using temperature-programmed reduction (TPR) and X-ray absorption spectroscopy (XAS), it is shown that the faster and larger oxygen release in the nanoporous material is responsible for twice as high Ni reduction than in the sintered system. For the nanoporous material, the nanoparticle formation mechanism, studied by in situ TEM and small-angle X-ray scattering (SAXS), follows the classical nucleation theory, while on sintered systems also small endogenous nanoparticles form despite the low Ni concentration. Biogas dry reforming tests demonstrate that nanoporous exsolved catalysts are up to 18 times more active than sintered ones with 90% of CO2 conversion at 800 °C. Time-on-stream tests exhibit superior long-term stability (only 3% activity loss in 8 h) and full regenerability (over three cycles) of the nanoporous exsolved materials in comparison to a commercial Ni/Al2 O3 catalyst.

Bimetallic Exsolved Heterostructures of Controlled Composition with Tunable Catalytic Properties.

In this paper, we show how the composition of bimetallic Fe-Ni exsolution can be controlled by the nature and concentration of oxygen vacancies in the parental matrix and how this is used to modify the performance of CO2-assisted ethane conversion. Mesoporous A-site-deficient La0.4Sr0.6-αTi0.6Fe0.35Ni0.05O3±Î´ (0 ≤ α ≤ 0.2) perovskites with substantial specific surface area (>40 m2/g) enabled fast exsolution kinetics (T < 500 °C, t < 1 h) of bimetallic Fe-Ni nanoparticles of increasing size (3-10 nm). Through the application of a multitechnique approach we found that the A-site deficiency determined the concentration of oxygen vacancies associated with iron, which controlled the Fe reduction. Instead of homogeneous bimetallic nanoparticles, the increasing Fe fraction from 37 to 57% led to the emergence of bimodal Fe/Ni3Fe systems. Catalytic tests showed superior stability of our catalysts with respect to commercial Ni/Al2O3. Ethane reforming was found to be the favored pathway, but an increase in selectivity toward ethane dehydrogenation occurred for the systems with a low metallic Fe fraction. The chance to control the reduction and growth processes of bimetallic exsolution offers interesting prospects for the design of advanced catalysts based on bimodal nanoparticle heterostructures.

The Facts and Myths for the Use of Lasers in Orthopedic Surgery.

For the past three decades, laser use has been investigated, mainly on implant applications, as well as hard and soft tissue processing on orthopedics. However, despite significant technological advances and achievements in Biophotonics, lasers have yet to emerge as a successful tool for hard-tissue manipulation (e.g., osseous tissue). Indeed, a careful search in relevant literature reveals a limited number of laser-based clinical applications in orthopedics, except for the low-level laser therapy applications. In this review article, we give a brief overview of the biophysical mechanisms of bone tissue and biocompatible implants laser surgery and, in parallel, we summarize some specific pre-clinical and clinical laser applications in orthopedics. Taking into consideration the complexity of laser-based applications in inhomogeneous musculoskeletal biostructures and/or implants, it is justified to state that applying laser radiation is still an open field of multidisciplinary research before performing interventions in clinical praxis. The evidence from this study indicates the need for more experimental and theoretical studies regarding light transport on soft and hard tissues, in order to further enhance safe and efficient laser applications in orthopedics. This undoubtedly implies the need for developing modern light delivery devices for laser surgery, by means of implementing robotic guidance, specialized for medical procedures on various anatomic structures. The aforementioned studies could eventually revolutionize the clinical applications of laser technology in orthopedics.

Distraction Osteogenesis Technique for the Management of a Gustillo Type I Tibial Shaft Fracture Initially Managed with an Intramedullary Nail Device.

Fractures of the tibia shaft are the most common long bone fractures, especially in young male adults. Due to specific anatomical features, these fractures are more common than any other long-bone fracture. This is one of the main reasons they are associated with twice the incidences of deep infection compared with any other bone and can be combined with the presence of segmental bone defect. Many reconstruction techniques have been used to manage such cases, including Ilizarov technique, Masquelet technique, vascularized fibula transfer, and the monolateral external fixator. We present a case of a 21-year-old male patient who was admitted to our hospital for a Gustillo type I tibial shaft fracture which was initially treated by an intramedullary nail device. Two months postsurgery the patient presented with clinical signs of infection in the area of the fracture site, confirmed by an osteolytic lesion revealed radiographically. A surgical operation was performed that included a tibial osteotomy proximal to the defected bone, bone excision, and application of a LRS external fixation device. Antibiotic therapy was administrated based grown cultures, and regular follow-up X-ray revaluation was performed. After six months, the bone was radiologically united, the frame was removed, and the leg was protected in a walking boot while the patient used only partial weight bearing. The treatment of segmental bone defects associated with infection and soft tissue loss presents a great challenge, and the choice of the appropriate method requires further study.

Bimetallic Ni-Based Catalysts for CO2 Methanation: A Review.

CO2 methanation has recently emerged as a process that targets the reduction in anthropogenic CO2 emissions, via the conversion of CO2 captured from point and mobile sources, as well as H2 produced from renewables into CH4. Ni, among the early transition metals, as well as Ru and Rh, among the noble metals, have been known to be among the most active methanation catalysts, with Ni being favoured due to its low cost and high natural abundance. However, insufficient low-temperature activity, low dispersion and reducibility, as well as nanoparticle sintering are some of the main drawbacks when using Ni-based catalysts. Such problems can be partly overcome via the introduction of a second transition metal (e.g., Fe, Co) or a noble metal (e.g., Ru, Rh, Pt, Pd and Re) in Ni-based catalysts. Through Ni-M alloy formation, or the intricate synergy between two adjacent metallic phases, new high-performing and low-cost methanation catalysts can be obtained. This review summarizes and critically discusses recent progress made in the field of bimetallic Ni-M (M = Fe, Co, Cu, Ru, Rh, Pt, Pd, Re)-based catalyst development for the CO2 methanation reaction.

An Unusual Presentation of a Massive Acromioclavicular Joint Ganglion Cyst Geyser Sign Secondary to Massive Rotator Cuff Tear and Cuff Arthropathy.

A Geyser sign is a rare manifestation of acromioclavicular joint (ACJ) ganglion cysts that are seen in patients with massive rotator cuff tears and arthritis of the ACJ. We present a case report of a 70-yr-old male who was presented to our hospital with a massive AC ganglion cyst measuring 7 × 8 cm with normal shoulder function tests. Imaging studies revealed a massive rotator cuff tear, advanced cuff arthropathy, degeneration of the ACJ, and a Geyser sign (seen with magnetic resonance imaging). The cyst was initially aspirated but recurred, so open debridement distal clavicle resection and ganglion cyst excision were performed. Eight months following debridement, the patient visited the outpatient department with cyst recurrence and limited shoulder movement. A reverse shoulder arthroplasty was performed with good clinical results.

Morganella Morganii: An Unusual Case-Report of Shoulder Septic Arthritis.

Morganella morganii is a gram-negative, anaerobic, facultative bacillus that is part of the natural flora of the gastrointestinal system. In the rare event of joint effusion, it is known for its slow-paced progression of symptoms and occasional attacks and remissions leading to septic arthritis, and it is difficult to recognize and to address with a timely response. We present a case of a 95-year-old male hospitalized due to left shoulder septic arthritis. The symptoms commenced as simple discomfort in the joint, and 10 days later this was followed with pain and dysfunction, diffusion, and mild fever. Blood and pus cultures were obtained on the day of admission; arthroscopic debridement was performed the next morning; and wide-spectrum antibiotic treatment was initiated. Both blood and pus cultures isolated Morganella morganii, and the antibiotic regimen was adjusted to the antibiogram. Clinical and laboratory scores demonstrated signs of improvement, and the patient recovered within 3 months.

SEPSIS SECONDARY TO DELAYED PRESENTATION OF NECROTISING FASCIITIS OF THE THIGH-PRESENTATION OF TWO CASES WITH A POOR OUTCOME.

Necrotizing fasciitis is an extremely virulent form of infectious fasciitis. It affects skin, subcutaneous fat, and superficial and deep muscular fascia by rapidly progressive necrosis. We present two cases, a 54-year-old female patient and a 46-year-old male patient, who presented to the emergency department of our hospital 30 days and 14 days after the onset of symptoms, respectively, with progressively deteriorating pain and swelling of the thigh, accompanied by fever, nausea, sweating, shortness of breath, and sepsis. Clinical, laboratory, and imaging findings suggested thigh fasciitis, which was secondary to osteomyelitis of the femoral head in one case. Despite the urgent surgical exploration and debridement, multiple courses of various schemes of intravenous antibiotics administered, the numerous surgical debridements and interventions performed, and the prolonged hospitalization in the intensive care unit, both patients died due to multiple-organ failure and disseminated intravascular coagulation. Necrotizing fasciitis is of surgical urgency with a high mortality rate, and early surgical intervention is of vital importance. In both of these cases, delayed presentation to the hospital was of great significance to the final outcome.