Pseudo-piezoelectricity in calcium titanate and structural changes under electric field

Calcium titanate does not exhibit piezoelectric behaviour. However, in present study such behaviour is observed in calcium titanate prepared by sol-gel synthesis and densified by field assisted sintering. Presumably, the instability of regular TiO6 octahedra results in the off-centering of titanium positions in nanostructured bulk calcium titanate. As a consequence, piezoelectric behavior is observed in calcium titanate which is referred to "pseudo-piezoelectricity". This particular response is of great interest in biomedicine because it can improve osseointegration of implant materials.Die vorliegende Arbeit weist piezoelektrisches Verhalten von Calciumtitanat nach, das mittels Sol-Gel Synthese hergestellt und mittels Feld-Aktiviertem Sintern verdichtet wurde. Vermutlich verursacht die Instabilität regulärer TiO6 Oktaeder eine Verschiebung der Positionen von Titanatomen in Festkörpern aus nanostrukturiertem Calciumtitanat. Daher kann piezoelektrisches Verhalten, genannt "Pseudopiezoelektrizität", in Calciumtitanat beobachtet werden. Dieses Ergebnis ist von großem Interesse für biomedizinische Anwendungen zur Verbesserung der Osseointegration von Implantatmaterialien

Awareness of sleep hygiene in medical students of Kara-chi: A cross sectional study.

Introduction: Sleep, a neurobiological phenomenon, is very essential component for the behaviours of human beings. Sleep Hygiene is essentially a term which is used to understand lifestyle and environmental factors that influence sleep. A stu-dent when get admission in a university, it’s a turning point in his/her life as previ-ous routine is dramatically altered. This is more so if a student enters a medical college or university. While studying medicine the syllabus, timetables, duties, shifts are all manifold and hence it changes the complete environment and lifestyle of nearly all students. This in turn leads to drastic change in the pattern of sleep hygiene.Objective: This study was conducted to assess the awareness of sleep hygiene among medical students.Methodology: This cross-sectional study was conducted from March –August 2019. The approval of study sought from Ethical Review committee of Isra University. A self- administered questionnaire used to collect data after student’s verbal consent and ensuring their anonymity. Using convenient sampling technique 467 medical students were studied including those from 1st year to 5th year students. The data was analyzed using SPSS version 21.0.Results: Showed that 59.5% of the students have not heard about sleep hygiene, 31.5% have heard it and 9% of them were not sure about it.77% of participants use social media, 72% takes shower and 63% of the students wash their face before going to the bed.Conclusion: We concluded that majority of the medical students are unaware of Sleep Hygiene and a large portion of them uses social media before going to bed.Key Words: Sleep Hygiene, medical students, awareness

السرقة والانتحال في الأدب والجامعات وطرق مكافحتها: Plagiarism in Literature and Institutions: History, Forms and Prevention

Plagiarism is the act of unacknowledged borrowing of the writings of others and passing them as one’s own. This fraudulence is closely related to forgery and piracy. This article deals with plagiarism in literature and institutions. Literary plagiarism is not new; its history is very old and goes back to pre-Islamic period. In the present era, it has spread as pandemic due to modern facilities. Our literature and educational institutions are badly affected by it. There are different types of plagiarism: accidental plagiarism, intentional plagiarism and self-plagiarism. This article describes its various forms, and the ways to control and prevent it. Key words: Plagiarism, literature, educational intuitions, evolution, prevention, pre-Islamic period, form

A novel approach to fabricate load-bearing Ti6Al4V-Barium titanate piezoelectric bone scaffolds by coupling electron beam melting and field-assisted sintering

A critical-size bone defect in load-bearing areas is a challenging clinical problem in orthopaedic surgery. Titanium alloy (Ti6Al4V) scaffolds have advantages because of their biomechanical stability but lack electrical activity, which hinders their further use. This work is focused on the fabrication of Ti6Al4V-Barium Titanate (BaTiO3) bulk composite scaffolds to combine the biomechanical stability of Ti6Al4V with electrical activity through BaTiO3. For the first time, a hollow cylindrical Ti6Al4V is additively manufactured by electron beam melting and combined with piezoelectric BaTiO3 powder for joint processing in field-assisted sintering. Scanning electron microscope images on the interface of the Ti6Al4V-BaTiO3 composite scaffold showed that after sintering, the Ti6Al4V lattice structure bounded with BaTiO3 matrix without its major deformation. The Ti6Al4V-BaTiO3 scaffold had average piezoelectric constants of (0.63 ± 0.12) pC/N directly after sintering due to partial dipole alignment of the BaTiO3 tetragonal phase, which increased to (4.92 ± 0.75) pC/N after a successful corona poling. Moreover, the nanoindentation values of Ti6Al4V exhibited an average hardness and Young's modulus of (5.9 ± 0.9) GPa and (130 ± 14) GPa, and BaTiO3 showed (4.0 ± 0.6) GPa and (106 ± 10) GPa, respectively. It reveals that the Ti6Al4V is the harder and stiffer part in the Ti6Al4V-BaTiO3 composite scaffold. Such a scaffold has the potential to treat critical-size bone defects in load-bearing areas and guide tissue regeneration by physical stimulation

Cholangiocarcinoma in a Resected Biliary Cyst: Importance of Follow-up

Biliary cysts are rare cystic dilatations of the biliary tree. Biliary cysts are positively associated with several significant complications, amongst them, cholangiocarcinoma befalls the most dreadful one. The elevated incidence is 20-30% in the unresected cyst and 0.7% in resected cysts. Magnetic resonance imaging (MRI) scan, magnetic resonance cholangiopancreatography (MRCP) or a contrast-enhanced computed tomography (CECT) is applied for the initial diagnostic study but the ultimate diagnosis ordinarily requires the tissue biopsy. Currently, the sole curative option involves the complete surgical resection of the lesion, with standard chemotherapy and active radiation applied as an alternative for the unresectable tumors. Despite the curative surgery the percentage of eternal recurrence of the tumor indefinitely persists, and effective post-surgical surveillance is reasonably demanded. We report a case of 29-year-old female with local recurrence of cholangiocarcinoma in a previously resected biliary cyst type I. The curative resection of the choledochal cyst only minimizes the considerable risk of the possible development of future cholangiocarcinoma but it does not completely prevent it. The appropriate follow-up for potential patients who have been typically treated for a biliary cyst is unclear. The lethal course of cholangiocarcinoma is believed due to its slow asymptomatic growing phase. Therefore, to adequately screen for malignancy, periodic imaging along with annual liver tests represents a reasonable approach to prevent the possible development of this appalling complication.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Experimentation on Optimal Configuration and Size of Thin Cylinders in Natural Convection

In this paper, an experimental study of laminar, steady state natural convection heat transfer from heated thin cylinders in an infinite air medium has been reported. Two electrically heated cylinders having the same slenderness ratio (L/D) i.e. 6.1 but different diameters i.e. 3.8 cm and 5.08 cm were used. 105 experiments were carried out to study the effect of diameter and inclination angle of thin cylinder on natural convection heat transfer. After mandatory corrections of radiation and endcap heat losses, convective heat transfer results were presented in the form of local and average dimensionless numbers. For vertical configuration of thin cylinder, Nusselt number was varied from 52.99 to 95.10 corresponding to 1.28×108≤Ra*L≤1.08×1010. While for horizontal configuration,Nusselt number was varied from 10.74 to 17.78 corresponding to 9.42×104≤Ra*D≤8.17×106. Results were compared with the published data and found satisfactory as the maximum percentage difference was only 3.09%. The essence of research is that the heat transfer coefficient increases with decrease in diameter and increase in inclination angle. Smoke flow visualization was done to capture patterns of fluid flow. Finally, comparison was made to quantify increase in Nusselt number from slender cylinder as compared to the flat plate

Convection Heat Transfer from Heated Thin Cylinders Inside a Ventilated Enclosure

Experimental study was conducted to determine the effect of velocity of axial fan, outlet vent height, position, area, and aspect ratio (h/w) of ventilated enclosure on convection heat transfer. Rectangular wooden ventilated enclosure having top and front transparent wall was made up of Perspex for visualization, and internal physical dimensions of box were 200 mm × 200 mm × 400 mm. Inlet vent was at bottom while outlet vents were at the side and top wall. Electrically heated cylindrical heat source having 6.1 slenderness ratio was fabricated and hanged at the centre of the enclosure. To calculate heat transfer rates, thermocouples were attached to the inner surface of heat source with silica gel. Heat source was operated at constant heat flux in order to quantify the effect of velocity of air on heat transfer. It was observed that average Nusselt number was increased from 68 to 216 by changing velocity from 0 to 3.34 m/s at constant modified Grashof number i.e. 5.67E+09. While variation in outlet height at the front wall did not affect heat transfer in forced convection region. However, Nusselt number decreased to 5% by changing the outlet position from top to the front wall or by 50% reduction in outlet area during forced convection. Mean rise in temperature of enclosure increased from 8.19 K to 9.40 K by increasing aspect ratio of enclosure from 1.5 to 2 by operating heat source at constant heat flux i.e. 541.20 w/m2

Modelling, Simulation, and Control of a Flexible Space Launch Vehicle

Modern Space Launch Vehicles (SLVs), being slender in shape and due to the use of lightweight materials, are generally flexible in nature. This structural flexibility, when coupled with sensor and actuator dynamics, can adversely affect the control of SLV, which may lead to vehicle instability and, in the worst-case scenario, to structural failure. This work focuses on modelling and simulation of rigid and flexible dynamics of an SLV and its interactions with the control system. SpaceX's Falcon 9 has been selected for this study. The flexible modes are calculated using modal analysis in Ansys. High-fidelity nonlinear simulation is developed which incorporates the flexible modes and their interactions with rigid degrees of freedom. Moreover, linearized models are developed for flexible body dynamics, over the complete trajectory until the first stage's separation. Using classical control methods, attitude controllers, that keep the SLV on its desired trajectory, are developed, and multiple filters are designed to suppress the interactions of flexible dynamics. The designed controllers along with filters are implemented in the nonlinear simulation. Furthermore, to demonstrate the robustness of designed controllers, Monte-Carlo simulations are carried out and results are presented.Comment: Presented at 20th International Bhurban Conference on Applied Sciences and Technology (IBCAST), 202

Testing the validity and reliability of the Arabic version of the painDETECT questionnaire in the assessment of neuropathic pain

Introduction Neuropathic pain (NP) can cause substantial suffering and, therefore, it must be diagnosed and treated promptly. Diagnosis of NP can be difficult and if made by an expert pain physician is considered the gold standard, however where expert help may not be easily available, screening tools for NP can be used. The painDETECT questionnaire (PD-Q) is a simple screening tool and has been widely used in several languages. We developed an Arabic version of PD-Q and tested its validity and reliability. Methods The original PD-Q was translated into the Arabic language by a team of experts. The translated version of the PD-Q was administered to the study population, which included patients having moderate to severe pain for at least three months. Reliability of the Arabic version was evaluated by an intra-class-correlation coefficient (ICC) between pre- and post-measures and Cronbach’s α values. Validity was measured by receiver operating characteristic (ROC) curve. Expert pain physician diagnosis was considered as the gold standard for comparing the diagnostic accuracy. Results A total of 375 patients were included in the study, of which 153 (40.8%) patients were diagnosed with NP and 222 [59.2%] patients had nociceptive pain. The ICC between pre- and post-PD-Q scale total scores for the overall sample, NP group, and NocP group was 0.970 (95% CI, 0.964–0.976), 0.963 (95% CI, 0.949–0.973), and 0.962 (95% CI, 0.951–0.971), respectively. The Cronbach’s α values for the post-assessment measures in the overall sample, NP group, and nociceptive pain group, were 0.764, 0.684, and 0.746, respectively. The area under the ROC curve was 0.775 (95% CI, 0.725–0.825) for the PD-Q total score. Conclusion The Arabic version of the PD-Q showed good reliability and validity in the detection of NP component in patients with chronic pain

Mothers’ and Caregivers’ Knowledge and Experience of Neonatal Danger Signs: A Cross-Sectional Survey in Saudi Arabia

Introduction. The majority of neonatal deaths in developing countries occur at home. Many of these deaths are related to late recognition of the signs of a serious illness by parents and a delay in the decision to seek medical care. Since the health-seeking behavior of mothers for neonatal care depends on the mothers' knowledge about WHO recognized danger signs, it is essential to investigate their knowledge of these signs.Objective. To investigate the knowledge and the experience of mothers and caregivers towards the WHO suggested neonatal danger signs.Methods. A community-based study was conducted on mothers who had delivered or had nursed a baby in the past two years.Results. A total of 1428 women were included in the analysis. Only 37% of the participant's knowledge covered three or more danger signs. The frequently reported participants’ knowledge of danger signs in this study was for yellow soles (48.0%), not feeding since birth or stopping to feed (46.0%), and signs of local infection (37.0%). The majority (69.0%) of the participants had experienced at least one of the danger signs with their baby. The noteworthy frequent reports of the participants’ experiences were for yellow soles (27.0%), not feeding since birth or stopping to feed (25.0%), and umbilical complications (19.0%).Conclusion. The proportion of mothers with knowledge of at least three neonatal danger signs is low. There is a need for developing interventions to increase a mother’s knowledge of newborns danger signs