In this work, defect-free thin-film-composite (TFC) hollow fiber membranes containing various amino acid salts as CO2 facilitated transport carriers were fabricated via dip-coating. Four different ...amino acid salts, i.e., potassium prolinate (ProK), potassium argininate (ArgK), potassium glycinate (GlyK) and potassium cysteinate (CysK), were selected and embedded within polyvinyl alcohol (PVA) matrix. TGA, FTIR, SEM and humid mixed gas permeation test were used for the evaluation. Experiments show that adding amino acid salts into the PVA matrix significantly increases the CO2 permeance with little influence on the CO2/N2 selectivity. ProK was found the most effective within the four investigated mobile carriers; The addition of 40% ProK into the PVA matrix nearly doubled the CO2 permeance (from 399 to 791 GPU). The PVA/amino acid salt membranes also exhibited good long-term stability, in which both CO2 permeance and CO2/N2 selectivity remained nearly unchanged in a 20-h test and after a two-week shutdown period.
Display omitted
•Four amino acid salts were used as mobile carriers in PVA-based membranes to enhance CO2 transport.•Defect-free TFC hollow fiber membranes with selective layer thicknesses of <500 nm were fabricated.•Lab-size hollow fiber membrane module was prepared and tested using humid mixed feed gas.•Adding amino acid salt improves the CO2 permeance significantly without sacrificing the selectivity.•The membranes show good long-term stability in the test and after a shutdown operation.
The development of multilayer composite membranes for CO2 separation has gained increasing attention due to the desire for energy efficient technologies. Multilayer composite membranes have many ...advantages, including the possibility to optimize membrane materials independently by layers according to their different functions and to reduce the overall transport resistance by using ultrathin selective layers, and less limitations on the material mechanical properties and processability. A comprehensive review is required to capture details of the progresses that have already been achieved in developing multilayer composite membranes with improved CO2 separation performance in the past 15–20 years. In this review, various composite membrane preparation methods were compared, advances in composite membranes for CO2/CH4 separation, CO2/N2 and CO2/H2 separation were summarized with detailed data, and challenges facing for the CO2 separation using composite membranes, such as aging, plasticization and long-term stability, were discussed. Finally the perspectives and future research directions for composite membranes were presented.
Abstract Background Adhesive small bowel obstructions are the most common postoperative causes of hospitalization. Several studies investigated the diagnostic and therapeutic role of water-soluble ...contrast agent (WSCA) in predicting the need for surgery, but there is no consensus. Methods A systematic review and meta-analysis was done of studies on diagnostic and therapeutic role of oral WSCA. Results WSCA had a sensitivity of 92% and a specificity of 93% in predicting resolution of obstruction without surgery; diagnostic accuracy increased significantly if abdominal X-rays were taken after 8 hours. The administration of oral WSCA reduced the need for surgery (odds ratio .55, P = .003), length of stay (weighted mean difference −2.18 days, P < .00001), and time to resolution (weighted mean difference −28.25 hours, P < .00001). No differences in terms of morbidity or mortality were recorded. Conclusions The administration of WSCA is accurate in predicting the need for surgery; the test should be taken after at least 8 hours from administration. WSCA is a proven safe and effective treatment, correlated with a significant reduction in the need for surgery and in the length of hospital stay.
Although most patients with acute pancreatitis have the mild form of the disease, about 20-30% develops a severe form, often associated with single or multiple organ dysfunction requiring intensive ...care. Identifying the severe form early is one of the major challenges in managing severe acute pancreatitis. Infection of the pancreatic and peripancreatic necrosis occurs in about 20-40% of patients with severe acute pancreatitis, and is associated with worsening organ dysfunctions. While most patients with sterile necrosis can be managed nonoperatively, patients with infected necrosis usually require an intervention that can be percutaneous, endoscopic, or open surgical. These guidelines present evidence-based international consensus statements on the management of severe acute pancreatitis from collaboration of a panel of experts meeting during the World Congress of Emergency Surgery in June 27-30, 2018 in Bertinoro, Italy. The main topics of these guidelines fall under the following topics: Diagnosis, Antibiotic treatment, Management in the Intensive Care Unit, Surgical and operative management, and Open abdomen.
Acute appendicitis (AA) is among the most common causes of acute abdominal pain. Diagnosis of AA is still challenging and some controversies on its management are still present among different ...settings and practice patterns worldwide. In July 2015, the World Society of Emergency Surgery (WSES) organized in Jerusalem the first consensus conference on the diagnosis and treatment of AA in adult patients with the intention of producing evidence-based guidelines. An updated consensus conference took place in Nijemegen in June 2019 and the guidelines have now been updated in order to provide evidence-based statements and recommendations in keeping with varying clinical practice: use of clinical scores and imaging in diagnosing AA, indications and timing for surgery, use of non-operative management and antibiotics, laparoscopy and surgical techniques, intra-operative scoring, and peri-operative antibiotic therapy.
This executive manuscript summarizes the WSES guidelines for the diagnosis and treatment of AA. Literature search has been updated up to 2019 and statements and recommendations have been developed according to the GRADE methodology. The statements were voted, eventually modified, and finally approved by the participants to the consensus conference and by the board of co-authors, using a Delphi methodology for voting whenever there was controversy on a statement or a recommendation. Several tables highlighting the research topics and questions, search syntaxes, and the statements and the WSES evidence-based recommendations are provided. Finally, two different practical clinical algorithms are provided in the form of a flow chart for both adults and pediatric (< 16 years old) patients.
The 2020 WSES guidelines on AA aim to provide updated evidence-based statements and recommendations on each of the following topics: (1) diagnosis, (2) non-operative management for uncomplicated AA, (3) timing of appendectomy and in-hospital delay, (4) surgical treatment, (5) intra-operative grading of AA, (6) ,management of perforated AA with phlegmon or abscess, and (7) peri-operative antibiotic therapy.
The current COVID-19 pandemic underlines the importance of a mindful utilization of financial and human resources. Preserving resources and manpower is paramount in healthcare. It is important to ...ensure the ability of surgeons and specialized professionals to function through the pandemic. A conscious effort should be made to minimize infection in this sector. A high mortality rate within this group would be detrimental.This manuscript is the result of a collaboration between the major Italian surgical and anesthesiologic societies: ACOI, SIC, SICUT, SICO, SICG, SIFIPAC, SICE, and SIAARTI. We aim to describe recommended clinical pathways for COVID-19-positive patients requiring acute non-deferrable surgical care. All hospitals should organize dedicated protocols and workforce training as part of the effort to face the current pandemic.
Sourcing hydrogen with ceramic reactorsAn alternative to directly transporting hydrogen produced at large scales through steam reforming for applications such as vehicular fueling is smaller scale, ...on-site production from methane or carriers such as ammonia. The hydrogen produced must be separated from co-produced carbon dioxide or nitrogen. Proton ceramic electrochemical reactors can extract pure hydrogen from gas mixtures by electrolytically pumping protons across the membrane at 800°C, but as the extraction proceeds, temperature gradients and entropic effects lead to efficiency drops. Clark et al. developed a nickel-based glass-ceramic composite interconnect that allowed for the design of a more complex reactor pathway (see the Perspective by Shih and Haile). Counterflowing streams balanced heat flows and maintained stable operating conditions that enabled 99% efficiency of hydrogen recovery. —PDS
Small and large bowel obstructions are responsible for approximately 15% of hospital admissions for acute abdominal pain in the USA and ~ 20% of cases needing acute surgical care. Starting from the ...analysis of a common clinical problem, we want to guide primary care physicians in the initial management of a patient presenting with acute abdominal pain associated with intestinal obstruction.
CO2 separation performance in facilitated transport membranes has been reported depended not only on the CO2 carrier properties but also to a great extent on the polymeric matrix regarding the ...capacity of retaining water and carriers as well as the processability for coating defect-free ultra-thin films. In this study, the blends of hydrophilic polymers polyvinyl pyrrolidone (PVP) and polyvinyl alcohol (PVA) were studied to find an optimal polymer matrix to host carriers in facilitated transport membranes for enhanced CO2 separation. It is found out that the optimized blend is 50/50 PVA/PVP by weight, which shows a significant increase in the water uptake (from 63 to 84%) at equilibrium state compared to the neat PVA. Polyethyleneimine (PEI) was employed to provide sample carriers to evaluate the synergistic effect of PVA and PVP on the CO2 separation performance. A thin film composite (TFC) membrane of the optimized blend (50/50 PVA/PVP with 50 wt% PEI) was fabricated on polysulfone (PSf) porous support. The fabrication of the TFC membranes is simple and low cost, and CO2 permeance of the optimized blend membrane is nearly doubled with the CO2/N2 selectivity remained unchanged, showing great potential for industrial applications of the resulted membranes.
A polymeric matrix suitable to host CO2 facilitated transport carriers was optimized by blending PVA and PVP. The water-retention of the blend membrane and the processability for thin-film coating were improved, showing synergetic enhancement on CO2 separation permeance. Display omitted
Application of conventional polymeric membranes in CO₂ separation processes are limited by the existing trade-off between permeability and selectivity represented by the renowned upper bound. ...Addition of porous nanofillers in polymeric membranes is a promising approach to transcend the upper bound, owing to their superior separation capabilities. Porous nanofillers entice increased attention over nonporous counterparts due to their inherent CO₂ uptake capacities and secondary transport pathways when added to polymer matrices. Infinite possibilities of tuning the porous architecture of these nanofillers also facilitate simultaneous enhancement of permeability, selectivity and stability features of the membrane conveniently heading in the direction towards industrial realization. This review focuses on presenting a complete synopsis of inherent capacities of several porous nanofillers, like metal organic frameworks (MOFs), Zeolites, and porous organic frameworks (POFs) and the effects on their addition to polymeric membranes. Gas permeation performances of select hybrids with these three-dimensional (3D) fillers and porous nanosheets have been summarized and discussed with respect to each type. Consequently, the benefits and shortcomings of each class of materials have been outlined and future research directions concerning the hybrids with 3D fillers have been suggested.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
PDF
