FINITE ELEMENT INVESTIGATION OF INITIAL CLEARANCE EFFECT ON TUBE-TO-TUBESHEET JOINT STRENGTH

The tube-to-tubesheet joint strength is measured in terms of residual contact pressure between the tube’s outer surface and tubesheet hole surfaces. The joint integrity is affected by several design parameters, including the type of material and the initial radial clearance. To avoid weakening of joints due to excessive initial radial clearances Tubular Exchanger Manufacturer Association (TEMA) has set standards in which maximum over-tolerances are spelled out. The present work complements the experimental program on the effect of over-tolerance on heat exchangers tube-to-tubesheet joint strength. The finite element analysis first addressed the ligament effect on the residual stress in order to select a satisfactory sleeve diameter. Second, the initial clearance effect on contact pressure and percent tube wall reduction is performed. Results show that for low strain hardening materials the initial clearance effect is negligible. However, higher levels of strain hardening have a significant effect on residual stress and percent wall reduction. For low clearances, the finite element estimated residual contact pressure compared well with the analytical result and that inferred from the experimentally measured pull-out force. The variation of the percent wall reduction with initial clearance is found to be similar to that of the measured one

The Prevalence of Microorganisms in H1N1 Patients Compared to Seasonal Influenza in a Sample of Iraqi Patients

This study provides valuable information on secondary microbial infections in H1N1 patients compared to Seasonal Influenza in Iraqi Patients. Nasopharynx  swabs were collected from  (12 ) patients  infected with Seasonal influenza (11  from Baghdad  and 1 Patient from south of Iraq) ,and ( 22 ) samples from patients with 2009 H1N1 ( 20 from Baghdad and  2 from  south of Iraq). The results show that the patients infected with 2009 H1N1 Virus were younger than healthy subjects and those infected with seasonal influenza. And the difference reached to the level of significance     (p< 0.01) compared with healthy subjects.Two cases infected with 2009 H1N1 virus (9.1%) were from south of the Iraq and remaining 20 cases were from Baghdad . Polymicrobial isolates from nasopharynx swab were observed in patients infected with 2009 H1N1 virus. Polybacterial infections (2-7 microorganisms) and fungal infection were reported in 21 out of 22 patients (95.5%) and 5 out of 22 (22.7 %) respectively.The predominant isolated microorganisms were Streptococcus pyogenes , Staphylococcus aureus and Streptococcus pneumoniae  were found in 95.2 %  , 95.2 % and 90.5 %  respectively .The results also show  that seven microorganisms were isolated from 10 (47.6 %) patients infected with 2009 H1N1 , no microorganism was isolated from patients infected with seasonal influenza or healthy persons. Key words: Seasonal Influenza , 2009 H1N1, Nasopharynx  swab

A Case Series of Severe Hospitalized COVID-19 Patients Treated with Tocilizumab and Glucocorticoids: A Report from Saudi Arabian Hospital

Background: The clinical spectrum of COVID-19 is variable and ranges from asymptomatic, mildly symptomatic, moderately severe and severe disease. A small proportion might develop severe disease and may have cytokine storm. One of the therapeutic options to treat such cases is Tocilizumab (TCZ). In this study, we present cases of severe COVID-19 treated with TCZ and glucocorticoids and discuss the treatment responses. Methods: This is a retrospective observational study of severe COVID-19 cases treated with TCZ and glucocorticoids. The case series examined the characteristics and outcome of those patients. Results: This study included 40 Severe Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) confirmed patients who received TCZ and glucocorticoids. The mean age of the included patients was 57.55 (±Standard deviation 12.86) years. There were 34 (85%) males, 19 (47.5%) were obese (BMI >30), 13 (32.5%) over weight, and five (12.5%) normal weight. The mean days from positive SARS-CoV-2 polymerase chain reaction (PCR) test to admission was 1.641 (±3.2) days. Of the patients, 18 (45%) had diabetes mellitus, 14 (35%) had hypertension. The mean days from hospital admission to ICU was 1.8 (±2.6), 20 (50%) required mechanical ventilation, 39 (97.5%) had received prone position, seven (17.5%) had renal replacement therapy, 13 (32.5%) required inotropes, four (10%) had plasmapheresis, one (2.5%) had intravenous immunoglobulin, all patients received steroid therapy, and the majority 31 (77.5%) did not receive any anti-viral therapy. Of all the patients, six (15%) died, 28 (70%) were discharged and six (15%) were still in hospital. Conclusion: The overall mortality rate was lower than those cited in meta-analysis. As our understanding of the COVID-19 continues, the approach and therapeutics are also evolving

The prevalence of polypharmacy and hyper-polypharmacy among middle-aged vs. older patients in Saudi Arabia: a cross-sectional study

IntroductionPolypharmacy, the use of multiple medications, is a growing concern among middle-aged and older patients, posing potential risks and challenges in healthcare management.AimThis study aimed to identify the prevalence of polypharmacy and hyper-polypharmacy among populations of middle-aged vs. older patients and identify its associated common comorbidities and prescribed medications in Qatif Central Hospital (QCH), Saudi Arabia.MethodsPatients aged 40 years or older who presented to an outpatient medical care clinic at QCH, Saudi Arabia, between 1 January and 31 December 2021 were included, and their comorbidities, prescribed medications, and recent clinical laboratory test results were collected. The Charlson comorbidity index (CCI) score was calculated to predict the risk of mortality. Logistic regression was used to compute the association between the prevalence of polypharmacy and patient characteristics. The results were presented as odds ratios (ORs) and 95% confidence intervals (95% CIs).ResultsA total of 14,081 patients were included; 31% of the cohort comprised older patients, and 66% of the cohort was identified with polypharmacy. The majority of the polymedicated patients were presented to an internal medicine care unit (34%). The prevalence of polypharmacy was positively associated with CCI (OR = 3.4, 95% CI 3.3–3.6), having a disease related to the musculoskeletal system (MSD) (OR = 4.2, 95% CI 3.8–4.7), and alimentary tract and metabolism (ATM) (OR = 3.8, 95% CI 3.4–4.2). Conversely, the prevalence of polypharmacy was negatively associated with age (OR = 0.9, 95% CI 0.89–0.91) and patients with cardiovascular diseases (OR = 0.6, 95% CI 0.5–0.7).ConclusionPolypharmacy is still an ongoing concern. Patients, particularly those with diseases related to MSD or ATM, should be considered for reviewing prescriptions by pharmacists to reduce the risk of adverse drug reactions and future consequences of polypharmacy

Energy Demand and Temperature: A Dynamic Panel Analysis

This paper is a first attempt to investigate the effect of climate on the demand for different energy vectors from different final users. The ultimate motivation for this is to arrive to a consistent evaluation of the impact of climate change on key consumption goods and primary factors such as energy vectors. This paper addresses these issues by means of a dynamic panel analysis of the demand for coal, gas, electricity, oil and oil products by residential, commercial and industrial users in OECD and (a few) non-OECD countries. It turns out that temperature has a very different influence on the demand of energy vectors as consumption goods and on their demand as primary factors. In general, residential demand responds negatively to temperature increases, while industrial demand is insensitive to temperature increases. As to the service sector, only electricity demand displays a mildly significant negative elasticity to temperature changes

FINITE ELEMENT INVESTIGATION OF INITIAL CLEARANCE EFFECT ON TUBE-TO-TUBESHEET JOINT STRENGTH

The tube-to-tubesheet joint strength is measured in terms of residual contact pressure between the tube’s outer surface and tubesheet hole surfaces. The joint integrity is affected by several design parameters, including the type of material and the initial radial clearance. To avoid weakening of joints due to excessive initial radial clearances Tubular Exchanger Manufacturer Association (TEMA) has set standards in which maximum over-tolerances are spelled out. The present work complements the experimental program on the effect of over-tolerance on heat exchangers tube-to-tubesheet joint strength. The finite element analysis first addressed the ligament effect on the residual stress in order to select a satisfactory sleeve diameter. Second, the initial clearance effect on contact pressure and percent tube wall reduction is performed. Results show that for low strain hardening materials the initial clearance effect is negligible. However, higher levels of strain hardening have a significant effect on residual stress and percent wall reduction. For low clearances, the finite element estimated residual contact pressure compared well with the analytical result and that inferred from the experimentally measured pull-out force. The variation of the percent wall reduction with initial clearance is found to be similar to that of the measured one