Comparative Analysis of Long-Term Outcomes in Valve-Sparing Aortic Root Reimplantation: Full Sternotomy versus Mini-Sternotomy Approach.

Background: Aortic valve-sparing aortic root replacement (VSARR) David procedure has not been routinely performed via minimally invasive access due to its complexity. Methods: We compared our results for mini-VSARR to sternotomy-VSARR from another excellence center. Results: Eighty-four patients, 62 in the sternotomy-VSARR group and 22 in the mini-VSARR group, were included. A baseline, the aneurysm dimensions were higher in the mini-VSARR group. Propensity matching resulted in 17 pairs with comparable characteristics. Aortic cross-clamp and cardiopulmonary bypass times were significantly longer in the mini-VSARR group, by 60 and 20 min, respectively (p < 0.001). In-hospital outcomes were comparable between the groups. Drainage volumes were numerically lower, and hospital length of stay was, on average, 3 days shorter (p < 0.001) in the mini-VSARR group. At a median follow-up of 5.5 years, there was no difference in mortality (p = 0.230). Survival at 1, 5 and 10 years was 100%, 100%, and 95% and 95%, 87% and 84% in the mini-VSARR and sternotomy-VSARR groups, respectively. No repeat interventions on the aortic valve were documented. Echocardiographic follow-up was complete in 91% with excellent durability of repair regardless of the approach: no cases of moderate/severe aortic regurgitation were reported in the mini-VSARR group. Conclusions: The favorable outcomes, reduced drainage, and shorter hospital stays associated with the mini-sternotomy approach underscore its potential advantages expanding beyond cosmetic outcome.

Differential diagnosis of thyroid orbitopathy - diseases mimicking the presentation or activity of thyroid orbitopathy.

Thyroid orbitopathy (TO) is the most common cause of orbital tissue inflammation, accounting for about 60% of all orbital inflammations. The inflammatory activity and severity of TO should be diagnosed based on personal experience and according to standard diagnostic criteria. Magnetic resonance imaging (MRI) of the orbit is used not only to identify swelling and to differentiate inflammatory active from non-active TO, but also to exclude other pathologies, such as orbital tumours or vascular lesions. However, a group of diseases can mimic the clinical manifestations of TO, leading to serious diagnostic difficulties, especially when the patient has previously been diagnosed with a thyroid disorder. Diagnostic problems can be presented by cases of unilateral TO, unilateral or bilateral TO in patients with no previous or concomitant symptoms of thyroid disorders, lack of symptoms of eyelid retraction, divergent strabismus, diplopia as the only symptom of the disease, and history of increasing diplopia at the end of the day. The lack of visible efficacy of ongoing immunosuppressive treatment should also raise caution and lead to a differential diagnosis of TO. Differential diagnosis of TO and evaluation of its activity includes conditions leading to redness and/or swelling of the conjunctiva and/or eyelids, and other causes of ocular motility disorders and eye-setting disorders. In this paper, the authors review the most common diseases that can mimic TO or falsify the assessment of inflammatory activity of TO.

Middle temporal gyrus approach to mesial temporal lobe tumours in children.

AIM OF THE STUDY: To assess whether the middle temporal gyrus (MTG) approach to mesial temporal lobe (MTL) tumours is an effective procedure for the treatment of epilepsy in children. CLINICAL RATIONALE FOR THE STUDY: MTL tumours are a common cause of drug-resistant epilepsy in children. There is as yet no consensus regarding their treatment. One possibility is resection via a MTG approach. MATERIAL AND METHODS: We assessed the medical records of patients treated at the Department of Neurosurgery, Children's Memorial Health Institute,Warsaw, Poland between 2002 and 2020. A prospectively maintained database including clinical, laboratory, and radiographic presentation, as well as pre- and post-operative course, was analysed. Patients with at least a one- -year follow-up were included. RESULTS: There were 14 patients aged 4-18 years who underwent a MTG approach for a MTL tumour. All presented with epileptic seizure, and none had neurological deficit on admission to hospital. Median follow-up was 2.5 years. Neuronavigation was used to adjust the approach, localise the temporal horn, and achieve radical resection of the tumour and the hippocampus. Gross total resection was performed in all cases. In most patients, histopathological examination revealed ganglioglioma. One patient had transient aphasia. Two patients developed hemiparesis after surgery, which later improved. One of them also experienced visual disturbances. Acute complications were more frequent in younger patients (p = 0.024). In all cases, MRI confirmed complete resection and there was no tumour recurrence during the follow-up period. 13/14 patients remained seizure-free (Engel class I). CONCLUSIONS AND CLINICAL IMPLICATIONS: The MTG approach to MTL tumours is an effective procedure for the treatment of epilepsy in children. It avoids removal of the lateral temporal lobe and poses only a minor risk of permanent neurological complications.

'Evaluation of beta-2-microglobulin and neuron-specific enolase as prognostic factors in patients over 65 years of age with frailty syndrome hospitalized for acute coronary syndrome'.

BACKGROUND: The aim of the study is to assess the value of beta-2-microglobulin (B2M) and neuron-specific enolase (NSE) as prognostic factors in the population of patients over 65 years of age with frailty hospitalized due to acute coronary syndrome (ACS). METHODS: Patients aged ≥65 years with ACS were included. Assessment of frailty was carried out using the FRAIL scale. The measurement of NSE and B2M was carried out three times during hospitalization: (1) at the time of admission, (2) on the second day of hospitalization, (3) on the seventh day of hospitalization, or the day of discharge if it was before the seventh day. The primary endpoint was all-cause mortality, and the secondary endpoint was unscheduled rehospitalization. RESULTS: Of the 127 patients, frailty was identified in 39.3%. Multivariate analysis of variance showed significantly higher levels of NSE (P = 0.012) and B2M (P < 0.001) in patients with frailty compared to the nonfrail group and significant changes in marker levels during hospitalization - decreased NSE (P < 0.001) and increased B2M levels (P < 0.001). Elevated B2M-1 level was an independent marker of the occurrence of frailty [odds ratio (OR), 1.98 (1.09-4.00); P = 0.044], and the optimal cutoff point for the diagnosis of frailty was 2.85 mg/l [area under the curve (AUC), 0.718 (0.632-0.795)] with sensitivity 52% and specificity 84.4% (P < 0.001). Elevated NSE-3 level was associated with all-cause mortality, and each 1 ng/ml increase in NSE-3 increased the risk of death by 1.07-fold [OR, 1.07 (1.03-1.10]). Meanwhile, elevated B2M-3 level was associated with unscheduled rehospitalization, and each 1 mg/l increase in B2M-3 increased the risk of unscheduled rehospitalization by 1.21-fold [OR, 1.21 (1.03-1.42)]. The Harrell's C-index for all-cause mortality was higher for NSE-3 [0.820 (95% confidence interval {CI}, 0.706-0.934)] compared to frailty assessed by the FRAIL scale [0.715 (95% CI, 0.580-0.850)], which means that additional NSE-3 assessment may improve the prediction of all-cause mortality. However, Uno's C-Statistic analysis showed that the difference was not statistically significant (Pr>chi-square 0.556). Harrell's C-index for unscheduled rehospitalization was higher for frailty assessed by the FRAIL scale compared to B2M-3. CONCLUSION: Monitoring NSE and B2M marker levels in patients over 65 years of age with frailty and ACS does not provide additional benefits in terms of prognostic ability compared to tests assessing frailty. B2M, assessed upon hospital admission and monitoring NSE and B2M levels during hospitalization may be considered in the diagnosis of frailty and risk stratification in a group of patients for whom currently available frailty diagnostic tools cannot be used.

Technological and Modelling Progress in Green Engineering and Sustainable Development: Advancements in Energy and Materials Engineering.

Due to a growing number of environmental issues, including global warming, water scarcity, and fossil fuel depletion, the topic of modern materials in energy is becoming crucial for our civilization. The technological advancements that have been observed bring many innovations that significantly impact how energy can be generated, stored, and distributed. Moreover, new opportunities have emerged in energy and materials engineering due to the increasing computational capability of current data processing systems. Methods that are highly demanding, time-consuming, and difficult to apply may now be considered when developing complete and sophisticated models in many areas of science and technology. Combining computational methods and AI algorithms allows for multi-threaded analyses solving advanced and interdisciplinary problems. Therefore, knowledge and experience in this subject, as well as the investigation of new, more efficient, and environmentally friendly solutions, currently represent one of the main directions of scientific research. The Special Issue "Advances in Materials: Modelling Challenges and Technological Progress for Green Engineering and Sustainable Development" aims to bring together research on material advances, focusing on modelling challenges and technological progress (mainly for green engineering and sustainable development). Original research studies, review articles, and short communications are welcome, especially those focusing on (but not limited to) artificial intelligence, other computational methods, and state-of-the-art technological concepts related to the listed keywords within energy and materials engineering.

Enhanced Superconducting Critical Parameters in a New High-Entropy Alloy Nb0.34Ti0.33Zr0.14Ta0.11Hf0.08.

The structural and physical properties of the new titanium- and niobium-rich type-A high-entropy alloy (HEA) superconductor Nb0.34Ti0.33Zr0.14Ta0.11Hf0.08 (in at.%) were studied by X-ray powder diffraction, energy dispersive X-ray spectroscopy, magnetization, electrical resistivity, and specific heat measurements. In addition, electronic structure calculations were performed using two complementary methods: the Korringa-Kohn-Rostoker Coherent Potential Approximation (KKR-CPA) and the Projector Augmented Wave (PAW) within Density Functional Theory (DFT). The results obtained indicate that the alloy exhibits type II superconductivity with a critical temperature close to 7.5 K, an intermediate electron-phonon coupling, and an upper critical field of 12.2(1) T. This finding indicates that Nb0.34Ti0.33Zr0.14Ta0.11Hf0.08 has one of the highest upper critical fields among all known HEA superconductors.

The impact of frailty on in-hospital complications in elderly patients with acute coronary syndrome.

BACKGROUND: Acute coronary syndrome (ACS) is linked to a range of in-hospital complications, and age is recognized as risk factor for adverse events. Discrepancies between physiological and chronological age are explained by frailty. However, the relationship between frailty and in-hospital complications is not clear. METHODS: Assessment of frailty in patients was carried out using the FRAIL scale. In-hospital complications assessed included, bleeding, infection, arrhythmia, acute kidney injury (AKI), delirium, stroke/transient ischemic attack (TIA), liver injury, hypoglycemia, length of stay in the cardiac care unit (CCU). RESULTS: Of the 174 patients, frailty was identified in 39.1% and pre-frailty in 29.9%. Frailty was associated with a higher incidence of all types of bleeding (frail vs. robust: 45.5% vs. 16.7%, P < 0.001) and infection (54.4% vs. 11.1%, P < 0.001), including pneumonia/lower respiratory tract infections (LRTI) and urinary tract infections (UTI). Incidence of antibiotic therapy (52.9% vs. 13.0%, P < 0.001), atrial fibrillation (AF) (47.1% vs. 9.3%, P < 0.001), AKI (57.3% vs. 20.4%, P < 0.001), delirium (52.9% vs. 3.7%, P < 0.001), liver injury, were higher in frail patients (17.6% vs. 0, P = 0.001), whilst their length of stay in the CCU was longer (4 days (2-6.5) vs. 2 days (2-3), P < 0.001). Infections, pneumonia/LRTI, antibiotic therapy during hospitalization, the incidence of AF and liver injury were more often in patients with pre-frailty compared to the robust group. After adjustment for potential confounders, frailty remained independently associated with an increased risk of infection (OR: 3.3 [1.6-7.0]), including pneumonia/LRTI (OR: 2.5 [1.1-5.8]) and UTI (OR: 4.8 [1.8-12.5]). Frail individuals had an increased requirement for antibiotic therapy (OR: 3.9 [1.9-8.1]), and greater risk of AF (OR: 3.5 [1.3-9.3]), AKI (OR: 2.6 [1.2-5.3]) delirium (OR: 11.7 [4.8-28.7]), as well as having to stay longer in the CCU (> 3 days) (OR: 3.7 [1.9-7.3]). CONCLUSIONS: Frailty was associated with an increased risk of numerous in-hospital complications in elderly patients who had been hospitalized with ACS.

Acetone-Gasoline Blend as an Alternative Fuel in SI Engines: A Novel Comparison of Performance, Emission, and Lube Oil Degradation.

The disproportionate use of petroleum products and stringent exhaust emissions has emphasized the need for alternative green fuels. Although several studies have been conducted to ascertain the performance of acetone-gasoline blends in spark-ignition (SI) engines, limited work has been done to determine the influence of fuel on lubricant oil deterioration. The current study fills the gap through lubricant oil testing by running the engine for 120 h on pure gasoline (G) and gasoline with 10% by volume acetone (A10). Compared to gasoline, A10 produced better results in 11.74 and 12.05% higher brake power (BP) and brake thermal efficiency (BTE), respectively, at a 6.72% lower brake-specific fuel consumption (BSFC). The blended fuel A10 produced 56.54, 33.67, and 50% lower CO, CO2, and HC emissions. However, gasoline remained competitive due to lower oil deterioration than A10. The flash-point and kinematic viscosity, compared to fresh oil, decreased by 19.63 and 27.43% for G and 15.73 and 20.57% for A10, respectively. Similarly, G and A10 showed a decrease in total base number (TBN) by 17.98 and 31.46%, respectively. However, A10 is more detrimental to lubricating oil due to a 12, 5, 15, and 30% increase in metallic particles like aluminum, chromium, copper, and iron, respectively, compared to fresh oil. Performance additives like calcium and phosphorous in lubricant oil for A10 decreased by 10.04 and 4.04% in comparison to gasoline, respectively. The concentration of zinc was found to be 18.78% higher in A10 when compared with gasoline. A higher proportion of water molecules and metal particles were found in lubricant oil for A10.

[Optimization of the treatment of moderate to severe and active thyroid orbitopathy considering the recommendations of the European Group on Graves' Orbitopathy (EUGOGO) [Optymalizacja leczenia umiarkowanej do ciezkiej i aktywnej orbitopatii tarczycowej z uwzglednieniem zalecen European Group on Graves' Orbitopathy (EUGOGO)]].

Graves' disease (GB), also known as Basedow's disease, is the most common cause of hyperthyroidism, and thyroid orbitopathy (TO) is its most common non-thyroid manifestation with an incidence of 42.2/million people/year. Based on the guidelines of the European Graves' Orbitopathy Group (EUGOGO), certain management standards presented in our publication should be used to optimize and improve the efficacy of TO treatment. Deciding on the optimal treatment for both hyperthyroidism and TO requires a cooperative team of specialists: endocrinologist, ophthalmologist, radiation therapist, and surgeon, as well as consideration of the risk of relapse and possible complications of the treatment method. The inflammatory activity and severity of TO should be diagnosed based on the investigator's own experience and according to standard diagnostic criteria. Assessment of the inflammatory activity of TO can be performed using the clinical activity score (CAS) and using imaging methods - mainly MRI. The severity of TO is assessed using a seven-grade NOSPECS classification and a three-grade EUGOGO scale. In moderate to severe and active TO, i.v. methylprednisolone pulses are the treatment of choice. It is important to maintain the standard and regimen of treatment. The recommended standard as first-line treatment in most patients with moderate to severe and active TO is the combined use of methylprednisolone i.v. (cumulative dose of 4.5 g over 12 weeks) with concurrent administration of mycophenolate sodium 0.72 g per day for 24 weeks. In more severe forms of moderate to severe and active TO, a higher cumulative dose of methylprednisolone i.v. is recommended as an alternative first-line treatment (7.5 g) as monotherapy starting with a dose of 0.75 g once a week for 6 weeks and 0.5 g for a further 6 weeks. EUGOGO guidelines recommend that in cases of no clinical response after 6 weeks of first-line treatment with i.v. methylprednisolone and mycophenolate, after 3-4 weeks, a second course of i.v. methylprednisolone monotherapy should be started with a higher cumulative dose of 7.5 g. Other second-line treatment options are orbital radiotherapy with or without oral or i.v. systemic glucocorticosteroid therapy, cyclosporine, or azathioprine in combination with p.o. glucocorticosteroid, methotrexate monotherapy, and a group of biologic drugs rituximab, tocilizumab, teprotumumab). Keeping in mind that TO is a sight-threatening disease, we expect, through the treatment applied, to maintain full visual acuity, pain relief, single vision in the useful part of the visual field, and a positive cosmetic effect.

Comparison of the prognostic value of frailty assessment tools in patients aged ≥ 65 years hospitalized in a cardiac care unit with acute coronary syndrome.

BACKGROUND: Frailty is associated with adverse events in elderly patients with acute coronary syndrome (ACS). Our aim was to compare the prognostic value of four frailty scales in patients aged ≥ 65 years hospitalized with ACS in a cardiac care unit (CCU). METHODS: Patients aged ≥ 65 years with ACS were included. Frailty was assessed using the Fried frailty scale (reference standard), the Edmonton Frail Scale (EFS), the FRAIL scale, and the Clinical frailty scale (CFS). The primary end point was all-cause mortality and the secondary end point was unscheduled rehospitalization. RESULTS: One hundred and seventy four patients aged ≥ 65 years with ACS were recruited. The median follow-up was 637.5 days. Frailty was identified in 41.4%, 40.2%, 39.1% and 36.3% patients by the Fried frailty scale, EFS, FRAIL scale and CFS, respectively. The agreement coefficients were 0.88, 0.86, and 0.79 for the FRAIL scale, EFS and CFS, respectively. In the Cox regression model, frailty was associated with all-cause mortality regardless of the scale used (univariate: hazard ratio [HR] 95% CI = 10.5, 2.4-46.8 Fried frailty scale; 12.0, 2.7-53.4 FRAIL scale; 7.1, 2.0-25.2 EFS; 8.3, 2.4-29.6 CFS. Multivariate: HR = 5.1, 1.1-23.8 Fried frailty scale; 5.7, 1.2-26.8 FRAIL scale; 3.7, 1.0-14.0 EFS; 4.2, 1.1-15.9 CFS). The FRAIL scale had the highest HR. In the univariate analysis, frailty was associated with unscheduled rehospitalization (HR = 3.2, 1.7-6.0 Fried frailty scale; 3.4, 1.8-6.3 FRAIL scale; 3.5, 1.8-6.6 EFS; 3.1, 1.7-5.8 CFS). In the multivariate analysis, only the EFS independently predicted unscheduled rehospitalization (HR = 2.2, 1.1-4.63). CONCLUSIONS: Frailty assessed by the Fried frailty scale, FRAIL scale, EFS and CFS is associated with all-cause mortality and unscheduled rehospitalization in elderly patients hospitalized in a CCU with ACS. The adjusted HR of the FRAIL scale for all-cause mortality was the highest among the scales compared, whereas the EFS was an independent predictor of unscheduled rehospitalization. These data should be taken into consideration when choosing a frailty assessment tool.

Digital science platform: an interactive web application and database of osteological material for anatomy education.

BACKGROUND: To meet the remote-learning constraints imposed due to the COVID-19 pandemic, the Digital Science Platform was developed. Human anatomy courses require practical classes that involve working on prepared specimens, although access to such specimens has been restricted. Therefore, the aim was to prepare appropriate-quality, scanned 3D model databases of human bone specimens and an interactive web application for universal access to educational materials. MAIN BODY: The database is located on the pcn.cnt.edu.pl website and contains 412 three-dimensional osteological models created via a structured light scanner, tomography and microtomography. The webservice contains a search engine and enables interactive visualization of the models. The database can be accessed, without restrictions, by any student or researcher wishing to use the models for noncommercial purposes. The stored models can be visualized with the open-source VisNow platform, which is also available to download from the webservice. The MariaDB backend database was deployed, and an Apache server with a personal home page (PHP) frontend was used. CONCLUSION: The models in the database are unique due to the specific digitalization process and skeleton specimen origin. Further development of the Digital Science Platform is foreseen in the near future to digitize other valuable materials.

Tirzepatide - a dual GIP/GLP-1 receptor agonist - a new antidiabetic drug with potential metabolic activity in the treatment of type 2 diabetes.

The incretin hormones glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are responsible for up to 65% of postprandial insulin secretion. Tirzepatide, developed by Eli Lilly, is a dual GIP/GLP-1 receptor agonist in the form of a synthetic linear peptide; its acylation technology allows it to bind to albumin, thus making it possible to dose the drug once a week. This review summarizes the key characteristics and pharmacokinetics of tirzepatide. The authors present the results of a phase 1, 2, and 3 clinical trial on the effects of tirzepatide on glycaemic and lipid control and the beneficial effects on body weight in a dose-dependent manner in patients with type 2 diabetes mellitus (T2DM). Tirzepatide has the ability to reduce glycaemic levels, improve insulin sensitivity, reduce body weight, and improve lipid metabolism, which is critically important in T2DM. Tirzepatide administered by weekly subcutaneous injections appears to be a promising drug for the treatment of T2DM as well as cardiometabolic disorders. The mechanism of action and safety profile of tirzepatide potentially fills important gaps in the current treatment of T2DM.

Extracorporeal membrane oxygenation for severe COVID-19-associated acute respiratory distress syndrome in Poland: a multicenter cohort study.

BACKGROUND: In Poland, the clinical characteristics and outcomes of patients with COVID-19 requiring extracorporeal membrane oxygenation (ECMO) remain unknown. This study aimed to answer these unknowns by analyzing data collected from high-volume ECMO centers willing to participate in this project. METHODS: This retrospective, multicenter cohort study was completed between March 1, 2020, and May 31, 2021 (15 months). Data from all patients treated with ECMO for COVID-19 were analyzed. Pre-ECMO laboratory and treatment data were compared between non-survivors and survivors. Independent predictors for death in the intensive care unit (ICU) were identified. RESULTS: There were 171 patients admitted to participating centers requiring ECMO for refractory hypoxemia due to COVID-19 during the defined time period. A total of 158 patients (mean age: 46.3 ± 9.8 years) were analyzed, and 13 patients were still requiring ECMO at the end of the observation period. Most patients (88%) were treated after October 1, 2020, 77.8% were transferred to ECMO centers from another facility, and 31% were transferred on extracorporeal life support. The mean duration of ECMO therapy was 18.0 ± 13.5 days. The crude ICU mortality rate was 74.1%. In the group of 41 survivors, 37 patients were successfully weaned from ECMO support and four patients underwent a successful lung transplant. In-hospital death was independently associated with pre-ECMO lactate level (OR 2.10 per 1 mmol/L, p = 0.017) and BMI (OR 1.47 per 5 kg/m2, p = 0.050). CONCLUSIONS: The ICU mortality rate among patients requiring ECMO for COVID-19 in Poland was high. In-hospital death was independently associated with increased pre-ECMO lactate levels and BMI.

Characteristics of Impulse Carburization LPC Process.

In the present work, Pyrowear53 steel was subjected to the impulse carburizing LPC process. After carburation, the material was quenched and tempered. Postprocessing analyses included the measurement of hardness, carbon content, residual austenite, and residual stresses. The results revealed that the thermochemical treatment resulted in the formation of an approximately 1200 µm wide carburized layer. The results of hardness, carbon content, and residual austenite measurement showed a continuous gradient (drop) in the measured values within the carburized layer. However, the results of residual stresses revealed the existence of a local extremum, namely, a zone with higher compressive stresses at the depth between 600 and 1000 µm. This was explained by a different temperature for initiation of martensite transformation as a function of carbon content. This difference resulted in the occurrence of two martensite expansion fronts at two different depths, resulting in an increase in compressive stresses at the noted depth range. Moreover, it was concluded that this region was present for material containing between 0.8 and 0.4 wt% carbon for Pyrowear53.

The Use of Ion Milling for Surface Preparation for EBSD Analysis.

An electron backscattered diffraction (EBSD) method provides information about the crystallographic structure of materials. However, a surface subjected to analysis needs to be well-prepared. This usually requires following a time-consuming procedure of mechanical polishing. The alternative methods of surface preparation for EBSD are performed via electropolishing or focus ion beam (FIB). In the present study, plasma etching using a glow discharge optical emission spectrometer (GD-OES) was applied for surface preparation for EBSD analysis. The obtained results revealed that plasma etching through GD-OES can be successfully used for surface preparation for EBSD analysis. However, it was also found that the plasma etching is sensitive for the alloy microstructure, i.e., the presence of intermetallic phases and precipitates such as carbides possess a different sputtering rate, resulting in non-uniform plasma etching. Preparation of the cross-section of oxidized CM247 revealed a similar problem with non-uniformity of plasma etching. The carbides and oxide scale possess a lower sputtering rate than the metallic matrix, which caused formation of relief. Based on obtained results, possible resolutions to suppress the effect of different sputtering rates are proposed.

Experimental Investigation of an Intensified Heat Transfer Adsorption Bed (IHTAB) Reactor Prototype.

The first experience in the operation of intensified heat transfer adsorption bed reactor designed for low-pressure adsorption processes is presented in this paper. This work aims to assess the possibility of fluidizing the porous media bed induced by the pressure difference between the evaporator and the adsorption reactor. The conducted experimental research allowed indicating the type of silica gel recommended to use in fluidized beds of adsorption chiller. The fixed bed of silica gel was observed for the lower pressure differences, while fluidization appeared in the case of the pressure difference between the evaporator and the adsorption chamber higher than 1000 Pa. The most significant differences in the adsorption process between the fixed bed and the fluidized bed are revealed in the changes of sorbent temperatures. The silica gel bed was fluidized with water vapor generated in the evaporator.

The Effect of Adhesive Additives on Silica Gel Water Sorption Properties.

Adsorption chillers are characterized by low electricity consumption, lack of moving parts, and high reliability. The disadvantage of these chillers is their large weight due to low adsorbent sorption capacity. Therefore, the attention is turned to finding a sorbent with a high water sorption capacity and enhanced thermal conductivity to increase chiller efficiency. The article discusses the impact of selected adhesives used for the production of an adsorption bed in order to improve heat exchange on its surface. Experiments with silica gel with three commercial types of glue on metal plates representing heat exchanger were performed. The structure of samples was observed under a microscope to determine the coverage of adsorbent by glue. To determine the kinetics of the free adsorption, the amounts of moisture adsorbed and the desorption dynamics the prepared samples of coated bed on metal plates were moisturized and dried in a moisture analyzer. Samples made of silica gel mixed with the adhesive 2-hydroxyethyl cellulose, show high adsorption capacity, low dynamic adsorption, and medium dynamic desorption. Samples containing adhesive poly(vinyl alcohol) adsorb less moisture, but free adsorption and desorption were more dynamic. Samples containing the adhesive hydroxyethyl cellulose show lower moisture capacity, relatively dynamic adsorption, and lower dynamic desorption.

A Comprehensive, Three-Dimensional Analysis of a Large-Scale, Multi-Fuel, CFB Boiler Burning Coal and Syngas. Part 2. Numerical Simulations of Coal and Syngas Co-Combustion.

This paper presents the results of numerical computations for a large-scale OFz-425 CFB (circulating fluidized bed) boiler utilizing coal and syngas. Four different operating scenarios are considered, including the reference variant, corresponding to the conventional, mono-combustion of bituminous coal, and three tests involving replacement of secondary air and part of the coal stream with syngas fed by start-up burners. Pressure, gas velocity, temperature, and carbon dioxide distribution in the combustion chamber are discussed in the paper. The results indicate that the syngas supply leads to an increase in local temperature and carbon dioxide concentrations. The proposed concept is not advisable as it may lead to frequent emergency stops of the CFB boiler.

A Comprehensive Three-Dimensional Analysis of a Large-Scale Multi-Fuel CFB Boiler Burning Coal and Syngas. Part 1. The CFD Model of a Large-Scale Multi-Fuel CFB Combustion.

The paper is focused on the idea of multi-fuel combustion in a large-scale circulating fluidized bed (CFB) boiler. The article discusses the concept of simultaneous coal and syngas combustion. A comprehensive three-dimensional computational fluid dynamics (CFD) model is developed, which allows us to describe complex phenomena that occur in the combustion chamber of the CFB boiler burning coal and syngas produced from coal sludge.