Original Article
Medicine
Frank Ablin Derosow
Abstract
Cermet, an abbreviation used worldwide for a homogeneous mixture consisting of metals or alloys or one or more ceramic phases comprising approximately 15 to 18% by volume and relatively little solubility between the metal and ceramic phases at the preparation temperature. It is being used. A good definition ...
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Cermet, an abbreviation used worldwide for a homogeneous mixture consisting of metals or alloys or one or more ceramic phases comprising approximately 15 to 18% by volume and relatively little solubility between the metal and ceramic phases at the preparation temperature. It is being used. A good definition of the word ceramic can be found in "Ceramic index". Any unusual, non-metallic product that is exposed to high temperatures during manufacture or use. By way of example, but not exclusively, the ceramic is a metal oxide, braide, carbide, or combination or mixture of such materials; In which there are anions that play an important role in atomic structure and properties. With a specific source on cermet’s, this definition of a ceramic component can be expanded to include nitrides, carbonatites, and silicides. In a broad view, cermet’s are like a special type of hard and refractory materials in the general class of metal composites. This topic is well covered in scientific papers, especially in the spectrum of specific comparable fracture volumes and metallic components. Compared to composite layers, the combination of metal and non-metal in cermet’s occurs on a very small scale. The non-metallic phase is usually non-filamentous, but a number of fine non-coaxial grains are formed, which are well dispersed and attached to the metal matrix. If the metal or ceramic component is often in the form of filaments, the material should be considered as a composite material. The connection between the non-metallic phase and the metallic background creates important effects among cermet’s; This greatly affects the phase associations, solubility and wetting characteristics associated with ceramic and metal components.
Original Article
Medicine
Martin Viberman
Abstract
The process of hot extrusion of very fine cemented carbide powder with a combination of softener has been known for many years. This method has been successfully used for cermet’s to make simple prismatic shapes that have a large length to cross-sectional area ratio. Cylindrical and quadrangular ...
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The process of hot extrusion of very fine cemented carbide powder with a combination of softener has been known for many years. This method has been successfully used for cermet’s to make simple prismatic shapes that have a large length to cross-sectional area ratio. Cylindrical and quadrangular shapes and other sections can be easily made with this method, even making pipes is also possible. Depending on the plasticizer used (for example, polystyrene with the addition of dimethyl and diphenyl ether), the extrusion process requires temperatures between 160 and 175 degrees Celsius (320- and 350-degrees Fahrenheit). The process of complete and slow sticking under vacuum before full sintering is necessary and even vital to avoid stretching (from casting defects, from sagging), breaking or very small porosity. Twisting of bodies produced by extrusion similar to what happens in the plastic industry is acceptable for this process. In order to produce a high-quality product, hot pressing is necessary.
Original Article
Medicine
Frank Ablin Derosow
Abstract
A major improvement in the resistance to deformation in TiC cermet’s and at the same time as a reduction in brittleness is possible by changing the arrangement of the bonded alloy or the carbide phase or both. to give an example of an optimal adhesive composition is 22.5% nickel, 10% molybdenum, ...
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A major improvement in the resistance to deformation in TiC cermet’s and at the same time as a reduction in brittleness is possible by changing the arrangement of the bonded alloy or the carbide phase or both. to give an example of an optimal adhesive composition is 22.5% nickel, 10% molybdenum, and approximately 7% aluminum. Improvement of the compressive yield strength of the carbide phase is achieved by forming a solid solution of TiC with 10% by weight of Vc. The addition of approximately 10% by weight of TiM greatly increases the deformation resistance of cermet. It is believed that this increase is ultimately the result of two factors, the effect of re-purification of the grains and the hardening of the carbide phase in the solid solution. If the ratio of titanium nitride to titanium carbide increases, carbo-nitride undergoes changes in its structure, which under controlled conditions can greatly improve the strength and fracture toughness of cermet. In the early 1970s, it was discovered that in the ternary systems Ti-MO-C-N and Ti-W-C-N there is a miscible gap in complete solid solutions between MON, MOC, TiN, and TiC under controlled, single-phase process conditions. Homogeneous solid solution breaks spontaneously or immediately into two similar phases that have close network parameters, but have different chemical compositions.
Original Article
Medicine
Martin Viberman
Abstract
In the general field of cemented carbides, cobalt-bonded tungsten carbide groups are the category that has undergone the most development over the past three decades. Arrangements, physical properties, manufacturing methods and application of this class of materials have been reviewed in the cemented ...
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In the general field of cemented carbides, cobalt-bonded tungsten carbide groups are the category that has undergone the most development over the past three decades. Arrangements, physical properties, manufacturing methods and application of this class of materials have been reviewed in the cemented carbides article in this issue. In many applications, tungsten carbide bonded to cobalt has certain disadvantages. The properties of titanium carbide bonded to steel can be compared to the same material for tungsten carbide bonded to cobalt as follows: Titanium carbides bonded to steel respond to heat treatment and when the joint is in an annealed condition, it can be machined with conventional machines. Carbide bonded to fully hardened steel can be heated to a variety of temperatures. Hence, it obtains more ductility than tungsten carbide bonded to cobalt. Cemented tungsten carbides are materials with high modulus. Carbides bonded to steel have a modulus that is not greater than that of steel. The coefficient of thermal expansion of steel-bonded carbides is closer to that of steel than to cemented tungsten carbides. Both tungsten carbide and carbide products can be soldered.
Original Article
Medicine
Antonin Brklay
Abstract
Gray cast iron will be produced from the alloy of iron and carbon, which is about 2% more, or the cooling speed is low, or silicon, which causes the instability of cementite. Now, if the amount of carbon is less than 3.4%, low carbon gray cast iron is obtained, which is easier to cast than steels, which ...
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Gray cast iron will be produced from the alloy of iron and carbon, which is about 2% more, or the cooling speed is low, or silicon, which causes the instability of cementite. Now, if the amount of carbon is less than 3.4%, low carbon gray cast iron is obtained, which is easier to cast than steels, which may have pearlite and pearlite properties. In the first stages of cutting the sample from the main piece, you are aware of its clarity, softness and neatness, and after cutting, filing is also done easily. But sanding it because of its high level of softness would be a problem. The result is that this steel is hyperiotectoid and according to the internal structure, i.e. the background of ferrite and pearlite grains, we understand that it contains 0.4% carbon and 5% ferrite and 5% pearlite, so we conclude that the more pearlite in the metal structure, the higher the percentage. Carbon is also more and the lower the amount and percentage of carbon, the higher the amount of ferrite, and the darkness of the surface under the microscope is the reason for this claim. The presence of sheet graphite causes gray cast iron to have unique properties. including having good machinability in conditions where the degree of hardness is such that the resistance to wear is excellent. The ability to resist burning in the last stages of the loss of lubricants is good, as well as the unusual elastic property that makes it capable of vibration. Several different factors affect the germination and growth of graphite sheets so that these graphite sheets can appear in different shapes and forms.
Original Article
Chemical Engineering
Saeed Raveshi; Amin Ahmadpour
Abstract
Nowadays energy and electricity production is one of the major concern of governments. Electricity generation by solar systems is considered as one of the alternative for fossil fuels. There is a surge in the use of the solar chimney power plant in the recent years which accomplishes the task of converting ...
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Nowadays energy and electricity production is one of the major concern of governments. Electricity generation by solar systems is considered as one of the alternative for fossil fuels. There is a surge in the use of the solar chimney power plant in the recent years which accomplishes the task of converting solar energy into kinetic energy. In this study a numerical simulation and geometrical parameters optimization of the solar chimney is discussed. In this paper, solar chimney prototype in Manzanares, Spain, as a practical example is used. To explore the geometric modifications on the system performance (output power and efficiency), effect of chimney height, collector radius and collector height is studied. A numerical simulation in this paper were used to evaluate the performance of a solar chimney power plant system, in which the effects of various parameters on the relative static pressure, driving force, power output and efficiency have been further investigated. In order to validate the present work, upwind velocity in the solar chimney was compared with an experimental model.
Original Article
Chemical Engineering
Hossein Hosseini; Asef Zare
Abstract
Gas turbines are usually designed in such a way that the pressure of hot gases at the exit of the turbine and after the last moving blade is slightly lower than the atmospheric pressure. Therefore, in order to overcome the ambient pressure, a divergent duct is considered at the gas turbine outlet, and ...
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Gas turbines are usually designed in such a way that the pressure of hot gases at the exit of the turbine and after the last moving blade is slightly lower than the atmospheric pressure. Therefore, in order to overcome the ambient pressure, a divergent duct is considered at the gas turbine outlet, and in this way, the exhaust gases, which have a relatively high temperature, are sent to the surrounding atmosphere through the exhaust. The useful output power is transferred to the compressor and then to the generator. Today, the use of gas turbines in power plants and as a generator of electricity is very valuable. In addition, they are widely used in various industries such as space industries, marine platforms, petrochemical industries, etc. These turbines can be useful especially in parts of the electricity industry that require quick installation and commissioning, as well as in cases where the national electricity grid is lost. Speed in construction and installation, low investment cost and low maintenance cost, light weight and the possibility of using multiple fuels are among the advantages of gas turbines compared to other power plants. Current gas turbines are operated with fuels such as natural gas, diesel, low thermal value gases, methane, crude oil, oil. Regarding the disadvantages of these turbines, we can mention the low efficiency and the need for major repairs after fewer working hours and the changes in power and efficiency due to atmospheric changes.
Original Article
Medicine
Reza Eghdam Zamiri; Abdolreza Mehdinavaz Aghdam
Abstract
Introduction: moking increases the risk of postoperative pulmonary complications in patients receiving general anesthesia. During laparoscopic surgeries, the effects of pneumoperitoneum and carbon dioxide (CO2) insufflation may amplify these. Our goal was to compare the metabolic and blood gas analysis ...
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Introduction: moking increases the risk of postoperative pulmonary complications in patients receiving general anesthesia. During laparoscopic surgeries, the effects of pneumoperitoneum and carbon dioxide (CO2) insufflation may amplify these. Our goal was to compare the metabolic and blood gas analysis of patients who underwent laparoscopic surgeries while under general anesthesia compared to those who did not smoke.Material and Methods: After receiving approval from the institutional review board, the 60 patients undergoing laparoscopic cholecystectomy were split into two groups of 30 each: smokers and non-smokers. A arterial blood gas sampling was performed along with baseline hemodynamic parameters to evaluate and compare PCO2, pH, and bicarbonate (HCO3) values at different time intervals with respect to pneumo-peritoneum creation, between smokers and non-smokers.Results: Systolic blood pressure was higher at baseline in the smoker group, and oxygen saturation was noticeably lower. Smokers had significantly higher PCO2 and end-tidal CO2 at all timesConclusion: Between smokers and non-smokers, there is a clear distinction in baseline arterial blood gas characteristics. Smokers appear to be more susceptible to the metabolic effects of CO2 insufflation and elevated intraabdominal pressure.
Original Article
Medicine
Mehrdad Zamani Esfahlani; Saeid Charsouei
Abstract
Introduction: Surface electromyography (sEMG) changes as a result of traumatic spinal cord injury (SCI), which disrupts spinal and supraspinal pathways. The sEMG is a useful addition to current clinical testing and can capture the residual motor command in great detail, even in muscles below the level ...
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Introduction: Surface electromyography (sEMG) changes as a result of traumatic spinal cord injury (SCI), which disrupts spinal and supraspinal pathways. The sEMG is a useful addition to current clinical testing and can capture the residual motor command in great detail, even in muscles below the level of injury with seemingly absent motor activities. We aimed to explain how the sEMG properties are altered after SCI in this in-depth review.Material and Methods: Following a thorough review of the literature, we focused on sEMG analysis methods and signal characteristics post-SCI. Early reports, according to what we discovered, tended to be primarily concerned with the qualitative analysis of sEMG patterns before moving on to semi-quantitative scores and a more thorough amplitude-based quantification.Results: On the other hand, recent studies are still limited to an amplitude-based analysis of the sEMG, and there are opportunities to more thoroughly characterize the time- and frequency-domain properties of the signal as well as to fully utilize high-density EMG techniques. We advise incorporating a wider variety of signal properties into the neurophysiological evaluation following SCI and gaining a better understanding of the relationship between these sEMG properties and underlying physiology.Conclusion: Improved sEMG analysis may help in understanding the mechanisms of change after neuromodulation or exercise therapy, as well as provide a more thorough description of how SCI affects upper and lower motor neuron function and their interactions.
Review Article
Medicine
Saeid Charsouei; Mehrdad Zamani Esfahlani
Abstract
Introduction: There do not appear to be any distinct, accepted clinical or investigative standards for the diagnosis or, more importantly, the selection of cervical radiculopathy patients for surgery. To decide who to operate on and to give our patients a realistic prognosis estimate, it is critical ...
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Introduction: There do not appear to be any distinct, accepted clinical or investigative standards for the diagnosis or, more importantly, the selection of cervical radiculopathy patients for surgery. To decide who to operate on and to give our patients a realistic prognosis estimate, it is critical that we can pinpoint the subgroup most likely to benefit from surgery. The purpose of this study is to determine whether electromyography (EMG) studies can be used to pinpoint the subgroup that will recover more favorably from surgery.Material and Methods: The latency of muscle contractions is measured by recording MEPs, and the CMCT is calculated by subtracting the latency of nerve conduction from the cerebral cortex to the muscle via the corticospinal tract from the latency of nerve conduction between the spinal nerve root and the muscle where an electrode was attached. For BB-CMCT, APB-CMCT, and TA-CMCT, the cut-off values are 8 to 9 ms, 18 ms, and 20 ms, respectively.Results: In the entire sample, there was a 40% agreement between NPS, MRI, and the level or levels that had undergone surgery. In group A, two patients' sensory nerve conduction studies show associated evidence of median nerve compression at the wrist. In group B, none of the patients had evidence of nerve root compression on preoperative NPS, but all of the patients had evidence of disc bulge and narrowing of the exit foramina on MRI scans.Conclusion: This study has shown that preoperative NPS is useful in determining which cervical radiculopathy patients will benefit most from surgery. Patients who undergo preoperative abnormal needle EMG examination will likely benefit from surgical decompression and fusion much more than those who undergo preoperative normal EMG. Therefore, whenever evaluating a patient with cervical radiculopathy.
Original Article
Medicine
Omar A. Hassan; Behzad Nazari
Abstract
Introduction: The current American Thyroid Association (ATA) recommendations support the intravenous administration of a loading dose of levothyroxine and an empiric glucocorticoid as part of the initial therapy despite the lack of adequate evidence. SH may ultimately direct patients to the intensive ...
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Introduction: The current American Thyroid Association (ATA) recommendations support the intravenous administration of a loading dose of levothyroxine and an empiric glucocorticoid as part of the initial therapy despite the lack of adequate evidence. SH may ultimately direct patients to the intensive care unit (ICU) for organ support and specialized care. Material and Methods: The following baseline data were available at the time of ICU admission: demographics, the modified Charlson score, the Simplified Acute Physiology Score II (SAPS II), the SOFA score, the presence of an underlying thyroid condition, precipitating factors, clinical symptoms, and laboratory results. Results: Cardiovascular SOFA =2 patients had lower heart rates, higher arterial lactate, and a higher risk of aspiration pneumonia and cardiac arrest prior to ICU admission than those without hemodynamic impairment. Conversely, patients who did not have cardiovascular failure experienced hypercapnia more frequently. In the population as a whole with SH, the median TSH, FT4, and FT3 levels were 51pmol/L, respectively. Notably, there were no differences in thyroid hormone levels, SH etiology, or triggers between patients with and without hemodynamic impairment.Conclusion: The overall ICU and 6-month post-admission mortality rates were 26% and 39%, respectively, based on 82 patients with SH admitted to ICUs. Age, hemodynamic and respiratory failure, but not neurological failure, were factors that were strongly linked to fatal outcomes. This extremely high mortality for a treatable condition necessitates early diagnosis, prompt levothyroxine administration, and careful cardiac and hemodynamic monitoring. More information is still required to more precisely define the ideal dosage and route of administration for this critical treatment.
Review Article
Medicine
Parisa Mehrasa; Tala Pourlak
Abstract
Introduction: This is because the development of cytokine release syndrome (CRS) as the pathologic basis for the progression of severe Covid-19 disease is possible. Material and Methods: A two-step selection process that involved first screening studies based on their titles and abstracts and then reading ...
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Introduction: This is because the development of cytokine release syndrome (CRS) as the pathologic basis for the progression of severe Covid-19 disease is possible. Material and Methods: A two-step selection process that involved first screening studies based on their titles and abstracts and then reading the full texts of those studies was carried out independently by the two reviewers. Studies were considered if they were RCTs, observational cohorts, or case-control in design, described two or more patients diagnosed with Covid19, and reported measures of cytokine levels (with a focus on IL-6). The use of standardized data extraction tables allowed for the duplication of the data extraction process. Data were taken from the text of the article, the tables, and the graphs.Results: In all of the studies that were included, elevated IL-6 levels were found in Covid-19 patients. Numerous studies specifically found that patients with more severe (complicated) diseases had higher levels of IL-6 descriptions of other inflammatory markers, such as ferritin and IL2R. Six studies in total compared the levels of IL-6 in patients with complicated disease (those with ARDS, needing ICU admission, or having "severe" or "critical" presentations according to the Chinese New Coronavirus Pneumonia Prevention and Control Program score) and noncomplicated disease (those without the aforementioned criteria present).Conclusion: In this systematic review and meta-analysis, we show that elevated serum IL-6 levels are associated with complicated Covid 19 disease and that these elevated IL-6 levels are also significantly associated with poor clinical outcomes. This implies that an excessive host immune response and autoimmune injury may be the result of an initial SARS-CoV2 infection that progresses to a complicated disease. These results underline the necessity of continuing, carefully designed clinical studies to clarify the function of immunomodulation, specifically IL-6 inhibition, in the treatment of severe Covid-19.
Original Article
Medicine
Ramin Azhough; Mahsa Teimoury
Abstract
Introduction: Our study examined the predictive value of six miRNAs of interest for evaluating treatment with FOLFOX and FOLFIRI when used as a first-line therapeutic option in managing patients with metastatic colorectal cancer in this context and considering the importance of this first-line treatment ...
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Introduction: Our study examined the predictive value of six miRNAs of interest for evaluating treatment with FOLFOX and FOLFIRI when used as a first-line therapeutic option in managing patients with metastatic colorectal cancer in this context and considering the importance of this first-line treatment option in managing patients with metastatic CRC.Material and Methods: We select a combination of endogenous and exogenous control miRNAs to improve the accuracy of the exosomal miRNA expression because there is currently no widely accepted best practice for exosomal miRNA normalization. Recent evidence suggests that using the same type of RNA species (miRNAs) as normalizers may be a more accurate approach than using other RNA species, such as RNU6B small nuclear RNA (U6). Due to this, we include cel-miR-39 as a spike-in (2 108 transcripts) as an exogenous normalizer and miR-16-5p as an endogen normalizer based on prior research on exosomal miRNA normalization.Results: We examined the expression of these microRNAs in 17 patients under the FOLFIRI (FIRI) protocol and 14 patients under the FOLFOX (FOX) protocol at 2 different time points (baseline and post-chemotherapy) to determine the associations between the miRNAs of interest and the response to first-line chemotherapy. At baseline (B) and post-chemotherapy (PC), there were no statistically significant differences in microRNA expression between the two chemotherapy protocols.Conclusion: Our findings demonstrated the discriminatory power of exosomal miR-92a-3p, miR-146a-5p, miR-221-3p, and miR-484 for non-responder patients regardless of the treatment employed. High baseline levels of these genes were associated with a lack of response to FOLFOX chemotherapy. Increased exosomal levels of miR-143-3p and miR-221-3p at the start of therapy have a predictive value for shorter OS, whereas increased exosomal levels of miR-92a-3p and miR-486-5p are associated with lower OS and PFS1.
Original Article
Medicine
Shahram Ghasembaglou; Ali Reza Lotfi
Abstract
Introduction: In our study, we investigated the expression of XIST in LSCC cells and tissues and its functional role in cell proliferation, anti-apoptosis, migration and invasion from LSCC cells. Meanwhile, the relationship between XIST, miR-125b-5p, and TRIB2 was also revealed, which may provide a good ...
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Introduction: In our study, we investigated the expression of XIST in LSCC cells and tissues and its functional role in cell proliferation, anti-apoptosis, migration and invasion from LSCC cells. Meanwhile, the relationship between XIST, miR-125b-5p, and TRIB2 was also revealed, which may provide a good target for the treatment of LSCC associated with the XIST/miR-125b-5p/TRIB2 axis.Material and Methods: Transduced cells (2.5 x 103 cells/100 µl)/well) were prepared for growth analysis and seeded in 96 well plates. Cells were cultured for 24, 48, and 72 h until 10 μl of CCK-8 reagent (DOJINDO, Kumamoto, Japan) was added to each well and cultured for an additional 4 h. Optical density (OD value) was measured at an absorbance of 450 nm using a microplate readerResults: LSCC cell lines (AMC-HN-8 and M4E cells) and nasopharyngeal epithelial cells (NP69 cells) were also selected to examine XIST expression. qRT-PCR analysis data showed higher XIST in LSCC cells compared to NP69 cells. In summary, we found that XIST as an oncogene in LSCC may be an indicator of cancer progression.Conclusion: In this study, lncRNA XIST and TRIB overexpression and miR-125b-5p downregulation were observed in LSCC tissues and cells. High-grade XIST often indicates poor prognosis in LSCC patients. Inhibition of XIST slows cell growth and impairs cell metastasis and anti-apoptotic effects. Both XIST and TRIB2 have binding sites for miR-125b-5p, which was predicted for the first time in our study.
Review Article
Medicine
Moen Hosein Pour Feyzi; Majid Montazer Bavil Olyaee
Abstract
Introduction: The symptoms of anastomotic leak often appear only at a late stage or are nonspecific, with many different diagnoses and treatments available with no clear consensus on the underlying mechanisms. The purpose of this review is to provide a brief summary of the existing literature on the ...
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Introduction: The symptoms of anastomotic leak often appear only at a late stage or are nonspecific, with many different diagnoses and treatments available with no clear consensus on the underlying mechanisms. The purpose of this review is to provide a brief summary of the existing literature on the definition and classification of thoracic esophagectomy anastomotic leak, its importance and prevalence, as well as the different risk factors, diagnoses and treatments.Material and Methods: Scopus and PubMed electronic databases were searched to identify articles published between 1995 and 2022 on AL after esophagectomy. Terms used include: “anastomotic leak,” “esophageal cancer,” “cervical,” “intrathoracic,” “diagnosis,” “management,” “risk factor,” combined with Boolean “OR” function study Frequent references for further research and related publications are searched. There is limited English language.Results: Anastomotic leak is one of the most common complications after esophagectomy and is associated with increased morbidity and mortality. Many projects range from small studies to large collaborations aimed at identifying potential preoperative and perioperative risks and improving diagnostic and management procedures. Despite the increase in available data, many aspects of anastomotic leak remain problematic and no general guidelines exist. Conclusion: AL after esophagectomy has many causes, is complex, and can have serious complications that will later affect the outcome. Current treatment is based on an individualized approach and reliable international evidence will help improve the prevention and treatment of AL. Treatment and patient outcomes. Higher quality evidence for such guidelines is urgently needed. The introduction of the ECCG system is a first priority to provide an up-to-date international standard for comparing the results of treatment strategies.
