Constant Rate of Momentum Change Ejector: simulation, experiments and flow visualisation

An ejector is a momentum-transfer device that requires no external mechanical input or moving parts. However, ejectors have low performance due to irreversibilities such as viscous losses and shocks in the primary stream and diffuser. It has previously been argued that by maintaining a constant rate of momentum change along the ejector duct, shock losses could be eliminated or at least minimised, and so the Constant Rate of Momentum Change (CRMC) ejector was introduced. The CRMC configuration appears to have significant potential, but the CRMC design prescription relies on: (1) an arbitrary choice for the constant rate of momentum change along the length of the duct; and (2) complete mixing between primary and secondary streams at the entrance to the duct. This thesis investigates the themes of shock losses and mixing within a CRMC ejector using physical experiments and computational simulation. The CRMC ejector duct and the primary nozzle were manufactured using 3D printing technology and then an experimental test bench using air as the working fluid was assembled and successfully tested. The primary nozzle had a throat diameter of 3.2mm and an exit diameter of 13.6 mm; the CRMC duct had a throat diameter of 25.48 mm. Extensive experimental tests were carried out for primary pressure between 200 kPa and 270 kPa, and secondary pressure between 0.6 kPa and 5 kPa. The results demonstrate the primary nozzle exit position within the entrainment region has a limited effect on the ejector performance in terms of the entrainment ratio and critical back pressures. A gas dynamic model was used to compare the performance of the present CRMC ejector with different ejector profiles (both conventional and CRMC) working with different fluids. The CRMC ejector showed a slightly better performance in terms of entrainment ratio and compression ratio. When CFD simulations of the present CRMC ejector were compared with a conventional ejector at a similar operating condition, the total pressure of the CRMC ejector remained 15% larger than the conventional ejector but this higher performance was due to different primary flow shock structures, not due to improvements in the compression process within the diffuser. Differences in the primary flow structure are thought to be caused by the different contraction angle of the secondary flow area. Higher entrainment ratio and compression ratio were simulated for the CRMC ejector relative to the conventional ejector but were not as high as expected from the CRMC design. To investigate the mixing of the flow within the CRMC ejector, a laser-based visualization technique was developed. A transparent CRMC ejector test section was designed, fabricated, and operated in the ejector system using air as the working fluid. The laser-based flow visualisation used a laser light beam of diameter of 1mm to illuminate the seeded secondary flow and thus, the unmixed primary flow was defined. The wall static pressure of the seeded flow agrees well with that of the unseeded flow which indicates that the seeding has a very small effect on the flow. Analysis of the images by digital image processing tools enabled identification of the jet core flow length which was found to lie between 65mm and 95mm from the nozzle exit at the selected operating conditions. The primary and secondary flows entering the CRMC duct are certainly not fully mixed as assumed in the CRMC design prescription. Furthermore, enhancement of the distribution of the wall static pressure and centreline total pressure is not directly attributable to the CRMC prescription. The modest performance improvements associated with the present CRMC design relative to the performance of a conventional duct should be balanced against the added complexity associated with manufacturing a CRMC duct when considering the CRMC design for future applications

Transpleural systemic artery-pulmonary artery communications in the absence of chronic inflammatory lung disease. A case series and review of the literature

AIM: To describe the causes and computed tomography (CT) and angiographic appearances of transpleural systemic artery-pulmonary artery shunts in patients without chronic inflammatory lung disease and determine their best management. MATERIALS AND METHODS: All patients referred to a tertiary referral unit between January 2013 and January 2020 in whom a diagnosis of a systemic-pulmonary artery communication without underlying chronic inflammatory lung disease was subsequently made have been included in this report. Medical records and imaging findings were reviewed retrospectively. RESULTS: Ten patients (male: female ratio = 7:3; median age 42 years [range 22-70 years]) with systemic artery-pulmonary artery shunts without chronic inflammatory lung disease were identified. Five were misdiagnosed as having a pulmonary arteriovenous malformation and had been referred for embolisation. In six patients, there was either a history of accidental or iatrogenic thoracic trauma or of inflammatory disease involving the pleura, and in two patients, in whom a previous medical history could not be obtained, there were CT features suggesting previous pleural inflammatory disease. Two shunts were thought to be congenital. All individuals were asymptomatic other than one with localised thoracic discomfort that dated from the time of surgery. All patients were managed conservatively and have remained well with a median follow-up of 4.5 years (range 1-11.3 years). CONCLUSIONS: Localised transpleural systemic artery-pulmonary artery shunts in the absence of chronic inflammatory lung disease are usually related to previous thoracic trauma/intervention or abdominal or pulmonary sepsis involving a pleural or diaphragmatic surface. Congenital shunts are rare. The present study and much of the literature supports conservative management

Prevalence of ‘pouch failure’ of the ileoanal pouch in ulcerative colitis: A systematic review and meta-analysis

Background and aims The ileoanal pouch (IPAA) provides patients with ulcerative colitis (UC) that have not responded to medical therapy an option to retain bowel continuity and defecate without the need for a long-term stoma. Despite good functional outcomes, some pouches fail, requiring permanent diversion, pouchectomy, or a redo pouch. The incidence of pouch failure ranges between 2 and 15% in the literature. We conducted a systematic review and meta-analysis aiming to define the prevalence of pouch failure in patients with UC who have undergone IPAA using population-based studies. Methods We searched Embase, Embase classic and PubMed from 1978 to 31st of May 2021 to identify cross-sectional studies that reported the prevalence of pouch failure in adults (≥ 18 years of age) who underwent IPAA for UC. Results Twenty-six studies comprising 23,389 patients were analysed. With < 5 years of follow-up, the prevalence of pouch failure was 5% (95%CI 3–10%). With ≥ 5 but < 10 years of follow-up, the prevalence was 5% (95%CI 4–7%). This increased to 9% (95%CI 7–16%) with ≥ 10 years of follow-up. The overall prevalence of pouch failure was 6% (95%CI 5–8%). Conclusions The overall prevalence of pouch failure in patients over the age of 18 who have undergone restorative proctocolectomy in UC is 6%. These data are important for counselling patients considering this operation. Importantly, for those patients with UC being considered for a pouch, their disease course has often resulted in both physical and psychological morbidity and hence providing accurate expectations for these patients is vital

Glycogen synthase kinases 3α and 3β in cardiac myocytes: regulation and consequences of their inhibition

Inhibition of glycogen synthase kinase 3β (GSK3β) as a consequence of its phosphorylation by protein kinase B/Akt (PKB/Akt) has been implicated in cardiac myocyte hypertrophy in response to endothelin-1 or phenylephrine. We examined the regulation of GSK3α (which we show to constitute a significant proportion of the myocyte GSK3 pool) and GSK3β in cardiac myocytes. Although endothelin increases phosphorylation of GSK3 and decreases its activity, the response is less than that induced by insulin (which does not promote cardiac myocyte hypertrophy). GSK3 phosphorylation induced by endothelin requires signalling through the extracellular signal-regulated kinase 1/2 (ERK1/2) cascade and not the PKB/Akt pathway, whereas the reverse is true for insulin. Cardiac myocyte hypertrophy involves changes in morphology, and in gene and protein expression. The potent GSK3 inhibitor 1-azakenpaullone increases myocyte area as a consequence of increased cell length whereas phenylephrine increases both length and width. Azakenpaullone or insulin promotes AP1 transcription factor binding to an AP1 consensus oligonucleotide, but this was significantly less than that induced by endothelin and derived principally from increased binding of JunB protein, the expression of which was increased. Azakenpaullone promotes significant changes in gene expression (assessed by Affymetrix microarrays), but the overall response is less than with endothelin and there is little overlap between the genes identified. Thus, although GSK3 may contribute to cardiac myocyte hypertrophy in some respects (and presumably plays an important role in myocyte metabolism), it does not appear to contribute as significantly to the response induced by endothelin as has been maintained

Are Histopathological Changes of H. pylori Infection in Young Dyspeptic Patients Necessitate Endoscopy?

BACKGROUND: Helicobacter pylori is an important gastrointestinal infective bacteria with many serious complications including gastric erosions and ulceration, duodenal ulcer, gastric carcinoma and MALT gastric lymphoma. The gastric biopsy is commonly performed in H. pylori-positive dyspeptic individuals, and many previous researchers studied the histopathological features of infected gastric biopsies however little previous studies focused on the histopathological findings in young population in comparison to the older one. AIM: To make a focus on the histopathological effects of H. pylori infection in young patients compared with the older one and predicts the need for endoscopy in this population, also to estimates the prevalence of infection in Iraqi patients. MATERIAL AND METHODS: the sample for this study is 180 patients in total, they attended Marjan medical city in Iraq for dyspepsia of more than 3 months and prepared for OGD. Patients asked for their permission to do immunological tests for H. pylori. Both serology for H. pylori antibodies and stool for antigen tests are used, and the case is included in the study only if both tests were positive, after OGD, the gastric biopsies are processed and examined histopathologically. RESULTS: Normal gastric biopsy is the most common histopathological finding in young (&lt; 25 years) patients (75%) while chronic atrophic gastritis is the most common one in patients &gt; 25 years age (57%). The prevalence of Helicobacter pylori infection in dyspeptic patients was 73.3%, the correlation between infection and sex was insignificant (p-value 0.06), and no significant correlation between infection and age (p-value 0.07) was concluded. CONCLUSION: H. pylori-related histopathological changes of gastric mucosa in young (&lt; 25 years) are commonly mild and does not necessitate endoscopy at this age unless there are alarming signs

Local Reference Ranges of Thyroid Volume in Sudanese Normal Subjects Using Ultrasound

This study aimed to establish a local reference of thyroid volume in Sudanese normal subjects using ultrasound. A total of 103 healthy subjects were studied, 28 (27.18%) females and 75 (72.82%) males. Thyroid volume was estimated using ellipsoid formula. The mean age and range of the subjects was 21.8 (19–29) years; the mean body mass index (BMI) was 22.3 (16.46–26.07) kg/m2. The overall mean volume ± SD volume of the thyroid gland for both lobes in all the patients studied was 6.44 ± 2.44 mL. The mean volume for both lobes in females and males were 5.78 ± 1.96 mL and 6.69 ± 2.56 mL, respectively. The males' thyroid volume was greater than the females'. The mean volume of the right and left lobes of the thyroid gland in males and females were 3.38 ± 1.37 mL and 3.09 ± 1.24 mL, respectively. The right thyroid lobe volume was greater than the left. The values obtained in this study were lower than those reported from previous studies

The effect of COVID-19 on the academic performance of Zayed University students in the United Arab Emirates

The outbreak of the coronavirus (COVID-19) pandemic led to significant changes across various sectors, including the field of education. In response to the pandemic, educational institutions worldwide, including Zayed University in the United Arab Emirates (UAE), transitioned to online learning. This study aimed to investigate the impact of COVID-19 on the academic performance of students in the UAE and their satisfaction with remote learning, while also examining gender differences in these variables. This study used a quantitative research design in which a questionnaire was used to collect data. The study employed a snowball sampling method to recruit a total of 1,780 male and female students aged 18 and above from Zayed University in the UAE. The collected data were analyzed using appropriate statistical techniques. This study revealed that students at Zayed University maintained a good level of academic performance (M = 3.34, SD = 0.76) during the COVID-19 pandemic and were satisfied with online learning (M = 3.48, SD = 0.84) during the COVID-19 pandemic. A significant positive correlation was observed between students’ academic performance and their level of satisfaction with online teaching during the COVID-19 pandemic (p \u3c 0.001). Furthermore, no significant differences were found between gender and both academic performance and level of satisfaction with online learning. Finally, we found that more males leaned toward online learning while more females leaned toward face-to-face learning. This study contributes to understanding the impact of COVID-19 on students’ academic performance and satisfaction with remote learning in the UAE context. The findings highlight the significance of student satisfaction for successful online learning and emphasize the need for adequate resources and the maintenance of education quality

The Pharmacological Activities of New Synthetic Compounds, in vitro and in vivo Studies

تعتبر مركبات البيرازول ومشتقاتها من المركبات المهمة طبيا ‘ والتي تجذب انتباه الباحثين ‘ وذلك لخصائصها الدوائية الواسعة ‘ حيث انها اثبتت فعاليتها كمركبات مسكنة للالم ومضادة للاتهابات اهداف الدراسة تهدف ھذه الدراسة لفحص النشاط المسكن للمركبات (تي بي دي) بطريقة نفض الذيل في الفئران البيضاء المعملية‘ ومن ثم اختيار افضلها نشاطا وتاثيرا لمزيد من الدراسات البيولوجية الأخري وتشمل: تقييم النشاط المضاد للالتهاب للمركب (تي بي دي - 04) عن طريق استحداث الالتهاب بواسطة مادة الكاراجينان ، وتمسخ الألبومين، و ثباتية غشاء كريات الدم الحمراء. دراسة التقرحات المعوية للمركب (تي بي دي - 04) عن طريق الحيوانات المعملية، یھدف ھذه البحث لدراسة الخواص الفارماكوداینامیكیة والتأثيرات الدوائية وتحديد آلية للمركب (تي بي دي - 04) الذي تقوم عليه عملها على امعاء الارنب المعزول باستخدام الطرق الفارماكولوجیة المتعارف علیھا علمیاً. منهجية إجراء الدراسة تم فحص النشاط المسكن المركبات (تي بي دي) في الجسم الحي النشاط مسكن بطريقة نفض الذيل في الفئران البيضاء المعملية بإستخدام ثلاث جرعات ]0.5 ،1 ، و 2 ملغرام/ كغ[ عن طريق الحقن داخل الفجوة البريتونية ، ثم تم التحقيق للمركب (تي بي دي- 04) في الجسم الحي لمعرفة نشاطة كمضاد للالتهابات عن طريق استحداث الالتهاب بواسطة مادة الكاراجينان بإستخدام ثلاث جرعات ]10 ،20 ، و 40 ملغرام/ كغ[ عن طريق الحقن داخل الفجوة البريتونية. وللتاكد من النتائج تم استخدام تجارب حيوية علي مستوي الانسجة (خارج جسم الحيوان) مثل ثباتية غشاء كريات الدم الحمراء و تمسخ الالبيومين عن طريق استخدام تراكيز تتراوح بين [900 إلي 0.9 ميكروغرام / مل]. ولدراسة التقرحات المعوية للمركب (تي بي دي - 04) تم إستخدام الفئران البيضاء المعملية بإستخدام ثلاث جرعات ]50 ،100 ، و 200 ملغرام/ كغ[ عن طريق الفم ، تم قياس معامل التقرح، معامل الشدة، ونسبة إجمالي التقرح. تم استخدام عقار ديكلوفيناك الصوديوم القياسي كدواء قياسي (مرجع) لدراسة النشاط المسكن والمضاد للالتهاب وكذلك لدراسة التقرحات المعويه للمركبات تحت الدراسة. للأنسجة المعزولة تم استخدام مجموعة من الادویة العیاریة مثل عقار الاستایلكولین، والسیروتونین، كلورید الباریوم، الاتروبین والسبروھیبتادین. وبعد إذابة المركب (تي بي دي - 04) فى المذیب العضوى ثنائي – میثل اوكسید الكبریت تم انشاء منحنى الجرعة والاستجابة الكامل له وللادویة القیاسیة بشكل منفرد او فى وجود جرعات فارماكولوجیة مختلفة من الشالات القیاسیة. بالإضافة لذلك تمت دراسة الخواص الفارماكوداینامیكیة المتوقعة للمركب (تي بي دي - 04) ببناء منحنى الجرعة والاستجابة للأدویة القیاسیة، ثم تحدید حساب قیمة كل من الجرعة التي تحدث نصف الفعالیة القصوى (EC50) ، الفعالیة القصوى (Emax) ، ومعامل الشال النوعي .(pA2) اٌستخدمت الادوية العيارية مثل عقار الاتروبين والسيبروهيبتادين لمعرفة الية الفعالية علي مستوي الانسجة. قورنت جميع النتائج اعلاه إحصائیا وستعتبر الاختلافات مھمة عند قیمة الاحتمالیة (p ≤ 0.05). النتائج أظهرت النتائج طريقة نفض الذيل أن مركبات (تي بي دي ) قد خفضت بشكل ملحوظ من الألم ‘وان الفعالية تزداد بزيادة الجرعة. المركب (تي بي دي - 04) اعطي انخفاضا ملحوظا من الالم (ع = 0.0003) مقارنة مع الدواء القياسي ويعطي أقصى فعالية كمون له في نفض الذيل (= 6.91، 6.25 و 6.04) ثانية في جرعة ]0.5 ،1 ، و 2 ملغرام/ كغ[ على التوالي في حين ان الدواء القياسي ديكلوفيناك الصوديوم ] 1 ملغرام/ كغ[ إعطاء فعالية كمون مع (= ثانية5.06). اظهرت نتائج استحداث الالتهاب بواسطة مادة الكاراجينان ان المركب (تي بي دي - 04) اعطي انخفاضا ملحوظا لوذمة كف القدم والاتهابات‘ بشكل ملحوظ (ع = 0.0103) وانه يعطي أقصى تثبيط له في الوقت 3 بالنسب المئوية (28.6 % و 25.0 % (. اظهرت النتائج عن طريق استخدام التجارب حيوية علي مستوي الانسجة (خارج جسم الحيوان) مثل ثباتية غشاء كريات الدم الحمراء و تمسخ الالبيومين فعالية واضحة للمركب (تي بي دي - 04)‘ حيث انه اعطي اقصي فعالية له في كلا التجربتين في تركيز ] 900 ميكروغرام/ مل[ وكانت النتائج مقارنة مع الدواء القياسي ديكلوفيناك الصوديوم في نفس التركيز باستخدام ثباتية غشاء كريات الدم الحمراء هي (97 % و 99 % على التوالي) ‘ وباستخدام تمسخ الالبيومين هي (61.1 % و 63.9 % على التوالي). كشفت نتائج دراسة التقرحات المعوية نتيجة تحمل عالية للمعدة للمركب (تي بي دي - 04) مقارنة مع الدواء القياسي ديكلوفيناك الصوديوم. اظھرت النتائج خلو المذیب العضوى (داي میثیل سلفوكساید) فى التركیز المستخدم للاذابه من اى تاثیر على امعاء الارنب المعزول، بینما اظھر المركب (تي بي دي - 04) انقباضا بسيطا علي النسيج المعزول ,وعند مقارنته مع عقارى الاستایلكولین والسرتونین مع انخفاض فاعلية وأقل فعالية (تقريبا ربع التأثير) لعقاري الاستایلكولین والسرتونین. وأثبتت الدراسة ان هذه التاثيرات تنسب لتاثيره الواضح في المستقبلات المسكارينية‘ والتاثير البسيط نسبيا في المستقبلات السيروتونينية. الخاتمة والتوصيات أظهرت النتائج أن المركب (تي بي دي - 04) له فوائد صحية محتملة حيث اثبت فعاليته كعقار واعد كمسكن ومضاد للالتهابات، مع إحتمالية منخفضة لتقرحات المعدة، بالتالي يمكن استخدامه لعلاج العديد من الأمراض مثل السرطان، الاضطرابات العصبية، والاضطرابات الالتهابية. المزيد من الدراسة مطلوبة علي هذه المركبات‘ خاصة على المستوى الجزيئي الدوائي، والتي قد تكشف الضوء على بعض الخصائص‘ وبالتالي اعطاء نتائج وتفسيرات دقيقة. مستقبلا‘ يؤخذ في الاعتبار، الآثار المحتملة من هذا المركب علي أمراض القلب