Multicriteria optimization of the composition, thermodynamic and strength properties of fly-ash as an additive in metakaolin-based geopolymer composites.

This paper presents the construction of intelligent systems for selecting the optimum concentration of geopolymer matrix components based on ranking optimality criteria. A peculiarity of the methodology is replacing discrete time intervals with a sequence of states. Markov chains represent a synthetic property accumulating heterogeneous factors. The computational basis for the calculations was the digitization of experimental data on the strength properties of fly ashes collected from thermal power plants in the Czech Republic and used as additives in geopolymers. A database and a conceptual model of priority ranking have been developed, that are suitable for determining the structure of relations of the main factors. Computational results are presented by studying geopolymer matrix structure formation kinetics under changing component concentrations in real- time. Multicriteria optimization results for fly-ash as an additive on metakaolin-based geopolymer composites show that the optimal composition of the geopolymer matrix within the selected variation range includes 100 g metakaolin, 90 g potassium activator, 8 g silica fume, 2 g basalt fibers and 50 g fly ash by ratio weight. This ratio gives the best mechanical, thermal, and technological properties.

Solitary Extramedullary Plasmacytoma With Development of T-cell Anaplastic Large-Cell Lymphoma: A Rare Case Report and Literature Review.

Solitary extramedullary plasmacytomas are an exceedingly rare form of malignant neoplasms characterized by a single localized mass located in any soft tissue that consists of abnormal plasma cells. This type of tumor is characterized by the absence of plasmacytosis on bone marrow biopsy, the absence of other lesions on imaging, and no clinical signs of multiple myeloma. They usually present with mass effect, so the clinical picture varies based on the location of the tumor. In cases where the tumor is located in the gastrointestinal tract, patients may experience abdominal pain, small bowel obstruction, or gastrointestinal bleeding. The diagnostic process typically involves imaging to identify the tumor and its location, followed by a biopsy of the lesion with subsequent immunohistochemical analysis, as well as fluorescence in situ hybridization, and finally, bone marrow biopsy. Treatment options vary depending on the tumor's location and may include radiation therapy, surgical resection, and chemotherapy. Currently, radiation therapy is the preferred first-line treatment, with the best outcomes reported in the literature. Surgery is also frequently used and is often followed by radiation therapy. While chemotherapy has not been shown to have significant benefits, the available data is insufficient, and further studies are required to make better conclusions. Disease progression is often associated with transformation to multiple myeloma, but due to the rarity of the disease, data is limited, and it remains unclear if other forms of progression exist.   We report a case of a 63-year-old male who presented to the hospital with symptoms of abdominal pain, nausea, and vomiting. A computed tomography scan revealed a mass causing bowel obstruction, which was subsequently resected and evaluated by pathology. The final diagnosis was determined to be a solitary extramedullary plasmacytoma. Since the margins of the resected mass were clear, the patient was managed with solely clinical observation. Approximately eight months later, the patient was diagnosed with T-cell anaplastic large-cell lymphoma, ultimately leading to his passing 15 months after the initial diagnosis of solitary extramedullary plasmacytoma. We present this case to increase awareness of the rare condition of solitary extramedullary plasmacytoma and to highlight the potential association with T-cell anaplastic large-cell lymphomas, as demonstrated in this patient's case. Given the possibility of malignant transformation, close monitoring is warranted in similar cases.

Severe Central Hypoventilation Syndrome in a Patient With Anti-N-Methyl-D-Aspartate Receptor Encephalitis: Case Report and Review of the Literature.

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a condition that is characterized by a variety of psychiatric and neurological symptoms, including central hypoventilation syndrome (CHS). CHS presents with apnea or hypopnea and can vary in severity and rapidity of development but rarely leads to respiratory failure that requires mechanical ventilation. Our patient was diagnosed with anti-NMDAR encephalitis after he presented with classic symptoms, and cerebrospinal fluid analysis showed positive N-methyl-D-aspartate (NMDA) receptor antibodies. During the course of the disease, he developed CHS, which led to respiratory arrest. After treatment with corticosteroids, intravenous immunoglobulin, and plasma exchange, the patient's symptoms improved with complete resolution of the apneic episodes.

Experimental and Theoretical Study of Plastic Deformation of Epoxy Coatings on Metal Substrates Using the Acoustic Emission Method.

Propagation of acoustic emission signals in continuous conjugated media under real-time loading was explored. The results of explored plastic deformation polymer coatings on a metal base using the acoustic emission method with synchronization of deformations and the moments of occurrence of acoustic emission signals are presented. Using the principal component method, the acoustic emission spectra, which make it possible to trace the evolution of deformation transformation processes, were analyzed. Presented the results of theoretical and experimental studies on the separate propagation of acoustic emission vibrations in a polymer coating, a metal base, and their joint combination in the form of multilayer structures. Boundary problems of propagation of acoustic emission signals in the conjugation of continuous media are considered from the standpoint of an elastic continuum and wave representations. The main variables are the force that initiates the appearance of acoustic emission signals and the displacement that determines the propagation of elastic waves. Based on the local rearrangement of the internal structure of conjugated media under conditions of development of deformation processes in the material, the verification of the main theoretical models of energy spectrum acoustic signals in continuous media at the micro-, meso-, and macro-levels was carried out. In this work, we present experimental data on a set of basic acoustic emission characteristics for four-point bending. It is shown that the principal components method reduces the dimension of data while maintaining the least amount of new information. Using the method of principal components to determine the stages of plastic deformation of polymer coatings on a metal base using the acoustic emission method. With the digitalization of acoustic emission signals and noise filtering, new possibilities for isolating a weak signal at the noise level appear even when its amplitude is significantly lower than the noise level. The study results can be used to predict the degree of destruction of two-layer materials under loading.

Fire Resistance of Geopolymer Foams Layered on Polystyrene Boards.

Geopolymer foams are excellent materials in terms of mechanical loads and fire resistance applications. This study investigated the foaming process of geopolymers and foam stability, with a focus on the fire resistance performance when using polystyrene as the base layer. The main purpose is to define the influence of porosity on the physical properties and consequently to find applications and effectiveness of geopolymers. In this study, lightweight materials are obtained through a process called geopolymerization. Foaming was done by adding aluminum powder at the end of the geopolymer mortar preparation. The interaction between the aluminum powder and the alkaline solution (used for the binder during the mixing process) at room temperature is reactive enough to develop hydrogen-rich bubbles that increase the viscosity and promote the consolidation of geopolymers. The basic principle of thermodynamic reactions responsible for the formation of foams is characterized by hydrogen-rich gas generation, which is then trapped in the molecular structure of geopolymers. The geopolymer foams in this study are highly porous and robust materials. Moreover, the porosity distribution is very homogeneous. Experimental assessments were performed on four specimens to determine the density, porosity, mechanical strength, and thermal conductivity. The results showed that our geopolymer foams layered on polystyrene boards (with optimal thickness) have the highest fire resistance performance among others. This combination could withstand temperatures of up to 800 °C for more than 15 min without the temperature rising on the insulated side. Results of the best-performing geopolymer foam underline the technical characteristics of the material, with an average apparent density of 1 g/cm3, a volume porosity of 55%, a thermal conductivity of 0.25 W/mK, and excellent fire resistance.

The Theory of Similarity and Analysis of Dimensions for Determining the State of Operation of Structures under Difficult Loading Conditions.

A simulation mathematical model of the state of operability of metal structures under difficult operating conditions without stopping the equipment was developed in the form of similarity criteria found on the basis of the laws of conservation of data obtained experimentally during tensile and four-point bending tests. Criteria are proposed for the similarity of the state of the material of the samples and the products in service, in which the kinetics of destruction are determined through the rate of damage accumulation and the movement of the structural components of the material. The residual life of the equipment under conditions of complex deformation effects was determined based on the theory of similarity and the analysis of the dimensions of the parameters of acoustic emission in real time. The use of concepts and models of fracture mechanics when creating methods and criteria for assessing the results of diagnostics and monitoring allows important information about the technical state of objects to be obtained.

Chronic Idiopathic Intestinal Pseudo-Obstruction.

Chronic intestinal pseudo-obstruction (CIPO) is a rare, potentially debilitating gastrointestinal (GI) condition characterized by symptoms of intestinal obstruction with the absence of anatomic lesions. In this report, we present a case of an 86-year-old female who presented with severe abdominal discomfort, nausea, and vomiting for two weeks prior to presentation. Imaging studies revealed severe gastric distension with a lack of anatomic lesions. The patient was ultimately diagnosed with chronic idiopathic intestinal pseudo-obstruction (CIIP). The purpose of this case report is to raise awareness of this condition in the medical literature and discuss the epidemiology, pathophysiology, clinical manifestations, diagnostic workup, and treatment options of this disorder.

Deglutition Syncope Due to Exaggerated Vagal Reflex.

Swallow or deglutition syncope is an uncommon cause of syncope associated with bradyarrhythmia and hypotension during food swallowing. Early recognition of this condition is imperative but challenging. We report a case of a 60-year-old female who presented with a complaint of intermittent lightheadedness after swallowing food. An episode of presyncope was observed and a reduced pulse rate from baseline was noted when she was instructed to eat a candy bar in the clinic. Further workup revealed normal in-office electrocardiogram, bilateral carotid ultrasound, transthoracic echocardiogram, and videofluoroscopic swallow study. Our goal in presenting this case is to raise awareness of the condition in medical literature and provide a good understanding of its clinical manifestation to prevent life-threatening events.

Acute Pancreatitis: A Possible Side Effect of COVID-19 Vaccine.

For the first time, the mRNA technology was utilized to produce a vaccine against COVID-19 after the unprecedented pandemic equally affected every part of the world. Pfizer-BioNTech (BNT162b2) mRNA vaccine against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was granted emergency use authorization (EUA) by Food and Drug Administration (FDA) in December 2020. EUA has been widely discussed in the medical literature and the general public. The safety of the BNT162b2 vaccine has been investigated in short-term trials with data available for three months. We present a case of a 96-year-old female with a past surgical history of cholecystectomy who presented with acute onset severe abdominal pain a few days after getting the first dose of Pfizer-BioNTech COVID-19 vaccine. She was diagnosed with acute pancreatitis with a lipase level of 4036 U/L. Extensive history and investigations were unable to find any etiology. The patient was conservatively managed and discharged home without any complications. There has been some data available in medical literature showing an association between acute pancreatitis and COVID-19 infection. Trial data of Pfizer COVID-19 also shows one case of acute pancreatitis in the treatment group. There have also been individual cases of unexplained acute pancreatitis shared by medical professionals on online forums. Our main goal to write this case is to make medical literature aware of possible emerging side effects of the COVID-19 vaccine, one of such side effects being self-resolving uncomplicated acute pancreatitis.

Acute Pancreatitis in a Patient With COVID-19 After the Resolution of Respiratory Symptoms.

The gastrointestinal (GI) involvement, including acute pancreatitis (AP) from the novel coronavirus disease-2019 (COVID-19), is increasingly being reported. Recent evidence suggests that the pathogenesis of COVID-19 is mediated by the angiotensin-converting enzyme 2 (ACE-2) receptors and transmembrane protease serine 2 (TMPRSS2) for "priming," which is highly expressed in the pancreas. To our knowledge, there is no other reported case of AP associated with COVID-19 after the respiratory symptoms are resolved. In this article, we present a patient with COVID-19, who came with intractable epigastric pain and resolved respiratory symptoms. A diagnosis of AP complicated with COVID-19 was made after laboratory and imaging workup, which was successfully managed conservatively.

Gastric Epithelioid Angiosarcoma: An Unexpected Tumor in an Unexpected Location.

Angiosarcomas are aggressive neoplasms that arise from endothelial cells and can develop in any part of the body. Gastrointestinal angiosarcomas are very uncommon and can have a variable clinical presentation. We report a case of an 84-year-old female who presented with acute blood loss anemia. She underwent a gastrointestinal workup with esophagogastroduodenoscopy (EGD), which revealed two polyps in the stomach. Histologic evaluation of the polyps was indicative of angiosarcoma, and the diagnosis was eventually confirmed by immunohistochemical analysis with positive CD31, ERG, and FLI1 stains. This case is reported to demonstrate the importance of considering angiosarcoma in the differential for patients presenting with gastrointestinal bleeding.

A Rare Case of Small Bowel Obstruction Due to Sunflower Seeds Consumption in an Adult.

Small bowel obstruction can occur due to multiple etiologies, including intra-abdominal adhesions, hernias, strictures, Crohn's disease, and malignancies. An infrequent cause of small bowel obstruction can be seed bezoars. We present a case of a 72-year-old male who presented to the emergency department with a clinical picture of small bowel obstruction without any apparent risk factors for this condition. After thorough questioning, it was revealed that he had consumed a large number of sunflower seeds prior to the onset of symptoms. This eventually was proved to be the cause of his symptoms. The case is presented with the intent to highlight the necessity of acquiring dietary history in patients with high suspicion for bowel obstruction without any predisposing risk factors.

Acute Pancreatitis Induced by Linagliptin: A Rare but Dangerous Side Effect.

Diabetes mellitus type 2 (DMT2) is a highly prevalent disease both in the United States and worldwide. Multiple treatment options are currently available, and several new groups of medications have been introduced over the last couple of decades. One of these groups is dipeptidyl peptidase-4 (DPP-4) inhibitors. These medications have side effects, some of which are severe and potentially life-threatening; however, some of their side effects have been underreported since they are relatively new. When prescribing these medications, it is essential to be cautious, especially with patients at an increased risk of developing an adverse effect. We present the case of a 57-year-old male who developed DPP-4 inhibitor-induced acute pancreatitis after the initiation of linagliptin. The patient did not have any apparent risk factors for pancreatitis as he did not drink alcohol or smoke cigarettes, his lipid panel was within normal limits, and he had a cholecystectomy five years prior. His linagliptin was held in the hospital and discontinued post-discharge, which led to the resolution of his symptoms.

An Acoustic Emission Method for Assessing the Degree of Degradation of Mechanical Properties and Residual Life of Metal Structures under Complex Dynamic Deformation Stresses.

An acoustic emission method for assessing the degree of degradation of mechanical properties under conditions of complex dynamic deformation stresses is proposed. It has been shown that changing the operating conditions of metal structures, peak loads, external collisions, and thermally changing loads, which cannot be taken into account, leads to uncertainty and unpredictable structural changes in the material. This in turn makes it difficult to identify the state of the structure material to ensure trouble-free operation of the equipment. Changes in the mechanical properties under difficult loading conditions are identified by polynomial approximation of the results of AE measurements and the construction of boundary curves separating the operability region from the fracture region. This is achieved by approximating the experimental dependences of the acoustic parameters for various types of loading. This approach significantly expands the capabilities of the technical means of identification systems of metal structures, and in particular, allows the current state of the equipment and its suitability for further operation to be assessed without stopping the equipment in real time. It is of interest not only to fix the damage, but also to diagnose the processes of reducing the mechanical properties during the operation of the equipment.

Analysis of the Generation of Vibration Signals under Uniaxial Loading of Materials Using the Coherent Properties of Laser Radiation.

: The present article describes the results of theoretical and experimental investigations of the force response of materials to external tensile stresses. The method used is based on remote precision measurements of the amplitudes of the harmonics of vibration signals and synchronous fixation of deformations under load. It was determined that the shape of the propagating acoustic signal depends not only on the bias time, but also on the frequency. In addition, fixation of the moments of occurrence of the vibrational signals and determination of the number of excesses in the amplitudes of harmonics over the discrimination level allows structural models to be studied in order to diagnose the strength properties of materials under dynamic loading of solids. The experimental setup consisted of a P100 Labtest-2 tearing machine providing a loading speed of 6.22 mm/min, a Polytech PSV-400 vibrometer including lasers, and a computer. Measurements were made at frequencies of 0.4, 1.6, and 40 kHz. An analysis of the mathematical models of the occurrence and propagation of acoustic signals in a material under load is presented, and the features of their application are reported. Transferring the moments of occurrence of vibrational signals to a strain diagram from the applied load allows the development of physical processes of hardening and destruction of materials to be traced. The occurrence of vibrational signals under load can be used as an information parameter for the diagnosis of developing defects in the structure of materials under load.