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Mohsin Al-Maghrabi,1 Silvia Mamede,2 Henk G Schmidt,3 Aamir Omair,4– 6 Sami Al-Nasser,4– 6 Nouf Sulaiman Alharbi,4– 6 Mohi Eldin Mohammed Ali Magzoub7 1Department of Pediatrics, Imam Abdulrahman Alfaisal Hospital, Riyadh, Saudi Arabia; 2Institute of Medical Education Research Rotterdam, Erasmus University Rotterdam, Rotterdam, the Netherlands; 3Department of Psychology, Erasmus University Rotterdam, Rotterdam, the Netherlands; 4Department of Medical Education, College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia; 5King Abdullah International Medical Research Center, Riyadh, Saudi Arabia; 6Ministry of the National Guard - Health Affairs, Riyadh, Saudi Arabia; 7Department of Medical Education, United Arab Emirates University, Al Ain, United Arab EmiratesCorrespondence: Nouf Sulaiman Alharbi, Department of Medical Education, College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia, Email ns.alharbi@gmail.comBackground: Literature suggest that physicians’ high level of confidence has a negative impact on medical decisions, and this may lead to medical errors. Experimental research is lacking; however, this study investigated the effects of high confidence on diagnostic accuracy.Methods: Forty internal medicine residents from different hospitals in Saudi Arabia were divided randomly into two groups: A high-confidence group as an experimental and a low-confidence group acting as a control. Both groups solved each of eight written complex clinical vignettes. Before diagnosing these cases, the high-confidence group was led to believe that the task was easy, while the low-confidence group was presented with information from which it could deduce that the diagnostic task was difficult. Level of confidence, response time, and diagnostic accuracy were recorded.Results: The participants in the high-confidence group had a significantly higher confidence level than those in the control group: 0.75 compared to 0.61 (maximum 1.00). However, neither time on task nor diagnostic accuracy significantly differed between the two groups.Conclusion: In the literature, high confidence as one of common cognitive biases has a strong association with medical error. Even though the high-confidence group spent somewhat less time on the cases, suggesting potential premature decision-making, we failed to find differences in diagnostic accuracy. It is suggested that overconfidence should be studied as a personality trait rather than as a malleable characteristic.Keywords: overconfidence, diagnostic accuracy, medical errors, premature closure

The particle size effects on the kinetic parameters of two overlapping crystallization peaks of Se85Te10Sb5 chalcogenide glass were studied using differential scanning calorimetry (DSC) under experimental and predicted isothermal conditions. The crystallization kinetics parameters of the two peaks were separated based on the application of a multi-peak Gaussian function using the advanced thermokinetics software package (AKTS). The nonisothermal methods of Friedman, Kissinger–Akahira–Sunose and the minimization, in addition to the predicted isothermal method, were used to investigate the variation of the effective activation energy with the extent of crystallization and, hence, with temperature. The local Avrami exponent as a function of the crystalline volume fraction was obtained at a constant heating rate or temperature for nonisothermal and isothermal processes. Its value was found to vary with particle size. The crystallization process of the two peaks was found to follow the Avrami–Erofeev reaction model. [ABSTRACT FROM AUTHOR]

This work is an attempt to quantitatively investigate the non-isothermal crystallization kinetics of Zn10Se90 chalcogenide. The behavior of kinetics parameters suggested that it is appropriate to conduct the investigation in three different heating regimes [(1) β =3-15, (2) β =20-50, and (3) β =60-99 K min-1]. Quantitative methods based on the Friedman and Starink models were utilized to evaluate variation in activation energy as a function of reaction progress and temperature. Both models showed the same trend, with a small variation which might have been due to the approximation approach. The variation in activation energy suggested that the chalcogenide responded differently in each heatingrate regime. This behavior was observed for the results obtained from the two models. Avrami's equation and Matusita analysis were used to evaluate Avrami's exponents. The results showed good agreement, indicating the reliability of both approaches. [ABSTRACT FROM AUTHOR]

In this study, we report the preparation of polymer blend nanocomposites based on chitin (CT)/cashew gum (CG) with various contents of magnetite nanoparticles (Fe3O4). The fabricated nanocomposites were characterised by FT infrared (FTIR), X‐ray diffraction (XRD), high‐resolution transmission electron microscopy (HRTEM), magnetic property (vibrating sample magnetometry (VSM)), differential scanning calorimetry (DSC), thermogravimetry (TGA) and impedance analyser. FTIR study revealed the characteristic absorption and shifts of peaks of the blend matrix, the shifts being attributed to the intermolecular interaction of Fe3O4 nanoparticles with CT/CG segments. The amorphous domain of the blend decreased with an increase in the concentration of nanoparticles was observed from XRD analysis. The HRTEM images showed the uniform arrangement of nanoparticles within the CT/CG network. VSM studies showed the ferromagnetic nature of the blend composite with an increasing saturation of magnetism with super‐paramagnetic behavior. DSC and TGA results revealed that the glass transition temperature and thermal stability of the composites were increased by the addition of magnetite nanoparticles. AC and dielectric properties were much improved in the entire range of frequencies due to the interaction with Fe3O4 nanoparticles. The role of nanoparticles on mechanical properties has been carefully studied. The tensile strength and hardness of magnetite filled nanocomposites become significantly higher in comparison to unfilled compounds and the nanocomposite with 10 wt. % of nanoparticles showed the maximum tensile strength. POLYM. COMPOS., 39:E540–E549, 2018. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

This work focuses on the in situ chemical oxidative polymerization of aniline with different contents of cerium-doped titanium dioxide (Ce-TiO) nanoparticles for the synthesis of polyaniline (PANI)/metal-doped TiO nanocomposites. The interaction of nanoparticles with PANI segments was characterized by FT-IR, UV, XRD, SEM, DSC, TGA and conductivity studies. The sensitivity of ammonia gas through the fabricated nanocomposite was also evaluated with respect to different contents of nanoparticles. The shift in FT-IR peak and UV absorption bands of nanocomposite with respect to pure PANI was clearly observed from the spectroscopic studies. Results from XRD studies showed the uniform arrangement of nanoparticles within the polymer matrix. SEM analysis showed the uniform structure of nanocomposites with spherically shaped dispersion of metal oxide nanoparticles. DSC studies revealed the increased glass transition and melting temperature of nanocomposites with an increase in the concentration of nanoparticles indicating the strong intermolecular interaction between nanoparticles and the polymer chain. TGA showed a higher thermal stability of nanocomposites than that of pure PANI, and thermal stability increases with the increase in the concentration of nanoparticles. Electrical properties such as AC conductivity, dielectric constant and dielectric loss tangent of nanocomposites were greater than pure PANI, and the magnitude of these properties increased with the loading of nanoparticles. Like AC conductivity, the DC conductivity of nanocomposite increased with the loading of nanoparticles. The maximum electrical conductivity was noted for 7 wt% composite. The ammonia sensing properties of composite were higher than the pristine PANI. [ABSTRACT FROM AUTHOR]

Si-Fe-O samples were produced using combinatorial sputtering and ball milling methods. Their structures were characterized by X-ray diffraction and Mössbauer spectroscopy, and electrochemical characterization was performed in Li cells. All samples were amorphous or nanostructured, however alloy phase composition had a strong dependence on synthesis method. Sputtered samples comprised amorphous Si, Fe and Si-O phases, while those made by ball milling were found to contain Si, α-FeSi2 and Si-O phases. This resulted in different reversible capacities, depending on the alloy synthesis method. In all alloys, the presence of oxygen results in low initial coulombic efficiency (ICE) below 0.9 V, due to the formation Li-O species that irreversibly trap Li. However, the ICEs increase as the upper cutoff voltage is increased, and at an upper cutoff of 2.5 V the ICE has little dependence on oxygen content. Electrodes prepared from Si-Fe-O powders mixed with graphite have good cycling performance and high volumetric capacities (e.g. ~1938 Ah/L for a Si0.80Fe0.08O0.12/graphite electrode). [ABSTRACT FROM AUTHOR]

Thin films of Si1-xOx were produced using combinatorial sputtering methods. X-ray diffraction studies of these films show that they are amorphous or nanostructured. The effect of oxygen content on the electrochemical performance of these materials was studied. The reversible specific capacity (between 0.005 and 0.9 V) agrees with the assumption that Si1-xOx is made up of amorphous silicon, which can react to form Li3.75Si, and amorphous SiO2, which reacts to form Li4SiO4. The irreversible capacity increases with oxygen content when measured to a potential limit of 0.9 V vs Li/Li+ but further Li can be extracted from sites presumably near oxygen up to a potential of 2.0 V vs Li/Li+. However, such potentials for the negative electrode would not be reached in a full Li-ion cell. This work shows that the oxygen content in Si1-xOx should be optimized to produce materials with a reasonable active/inactive ratio in order to have electrodes with the desired specific capacity, an appropriate irreversible capacity and an appropriate amount of inactive phase to buffer volume expansion. [ABSTRACT FROM AUTHOR]

The purpose of this study is to evaluate the using of oscillatory baffled column in the field of ink removal by flotation Technology. Visualization and flotation experiments were carried out in a laboratory oscillatory baffled flotation column. Six central square orifice-plate baffles with equally spacing supported by two thin rods were installed in the column. The baffles are oscillated by a reciprocating mechanism. The mechanism was driven by a variable speed motor. The tested oscillation frequencies were 0.73, 0.98 and 1.64 Hz with corresponding oscillatory Reynolds number of 1007, 1351 and 2261. The oscillation amplitude was fixed at 2.2 cm. The experiments were conducted on the removal of HP commercial ink from water. The photographs showed the bubble distribution, bubble coalescence and vortex formation in the inter-baffle zone. The flotation results demonstrated the effect of both bubble distribution and enlargement on the ink recovery. For all tested frequencies, the ink recovery decreased in comparing to that of the unbaffled column. Finally, the present study indicates that further research is required to determine the optimal baffles geometry for application of this device in the filed of flotation technology. [ABSTRACT FROM AUTHOR]

Sand dunes in the Arabian Peninsula cause many problems for the population, environment and desert roads, which directly affects the regional development. Many studies have been carried out to solve this problem. However, they used agricultural and chemical materials to stabilize sand dunes which gave a limited success. This study used the non- active calcium bentonite ore from Khulais region, Saudi Arabia. The stabilization process by this proposed method is not only on the surface of sand dunes, but also to some depths from surface. That is to provide a relative thick bed on the sand dune surface, which has the ability to resist wind blew and be not able to be removed. In addition, it becomes able to conserve water for very long time. The present research deals with the comparison between surface and subsurface spraying of bentonite slurry in sand treatment. The method using subsurface spraying gives some improvement in the engineering properties of sand dunes. Their values increased to (1.5-4.0), twice the original values compared with only (1.0-2.50) twice of the original values in case of using surface spraying. These values have been obtained after 10 days of treatment and using only 2% of bentonite. [ABSTRACT FROM AUTHOR]

Froth flotation has been employed as a successful means of concentration of metalliferrous ores. Column flotation is a relatively new development. The process involves selective attachment of particles of certain minerals out of a slurry, descending a vertical column, to ascending air bubbles. There are some particles which attach themselves to the ascending air bubbles from the collection zone and go right up to the cleaning zone whereas others are attached for a while and are, then, detached. For certain other particles, the process of attachment and detachment is repeated. The probabilities of change from the attachment to detachment state of a particle are determined from the recoveries of the two zones. The paper explains the steady state probabilities of a particle from the probabilities of change from one state to another based on the principle of Markov process. [ABSTRACT FROM AUTHOR]

Background: Polyomavirus, known as BK virus, is an important cause of allograft dysfunction in renal transplant patients, leading to BK virus nephropathy. The main study objectives were to assess the disease incidence and disease course in pediatric patients, and assess the diagnostic accuracy of BK screening for asymptomatic patients., Methods: This is a single-center observational study, which included 81 pediatric renal allograft recipients that were transplanted and/or followed at King Fahad Specialist Hospital-Dammam, Saudi Arabia. Screening for BK virus was performed prospectively according to a predetermined hospital protocol. Our BK screening protocol consisted of periodic quantitative real time polymerase chain reaction test in the plasma. In patients with deranged graft function, graft biopsies were evaluated for the presence of BK nephropathy., Results: Our study detected BK viremia in 14 patients (17.3%), while BK nephropathy occurred in seven patients (8.6%). The onset of BK viremia had bimodal distribution, 78 percent occurring within first year post-transplantation, while 21.4% occurred late. Patients who developed BK nephropathy had a higher BK level than BK viremia patients, for both mean and peak values (p = .02, p = .02). A BK cutoff level of 40 000 copies/mL showed sensitivity and specificity of 85.7%, 85.7%, respectively, in predicting the conversion of BK viremia to BK nephropathy., Conclusions: BK viremia and BK nephropathy occur in pediatric patients with similar incidence rates compared to adult patients. Protocolized screening led to early detection of viremia, and could predict the conversion of BK viremia to BK nephropathy and allow for early immunosuppression modulation., (© 2023 Wiley Periodicals LLC.)

The success of a pediatric kidney transplantation program can only be judged by reviewing its results. We aim to audit our short-term outcome of pediatric kidney transplantation at the King Fahad Specialist Hospital-Dammam. A retrospective chart review was performed to collect data about recipient demographics, etiology of end-stage kidney disease, type of dialysis, type of donor and outcome. Between September 2008 and April 2012, 35 pediatric kidney trans-plantations (<16 year) were performed of a total of 246 kidney transplants (14.2%). The mean age was 8.1 years, with a mean weight of 23.3 kg, and there were 21 (60%) boys in the study. Kidney dysplasia/hypoplasia was the most common etiology (51.4%). Preemptive kidney transplantation was performed in six (17%) patients. Peritoneal dialysis was the most common mode of dialysis [24 (69%) children]. Living donation was the source of kidney allografts in 13 (37%) cases. During a mean follow-up of 1.5 years, one patient died and one graft was lost due to kidney vein thrombosis. The one year patient and graft survival rates were 97% and 94%, respectively. Efforts should now be focused on achieving optimal long-term results. There is also a need to encourage preemptive transplantation and living donation in this population.

Background: The aim of our study was to use a quantitative measure of muscle strength to identify the muscle power at which the patient can safely ambulate unassisted after spinal anesthesia., Methods: Twenty ASA physical status I and II patients undergoing elective perineal or lower abdominal surgery under spinal anesthesia were enrolled in the study. Spinal anesthesia was conducted using 10 mg heavy bupivacaine. The regression of motor block was assessed both qualitatively using the Bromage score and quantitatively by measuring the isometric contraction of the knee, hip, and ankle flexors every 15 minutes until the patient was able to ambulate unassisted., Results: The rate of regression of the Bromage score was faster than regression of the isometric forces at all tested joints. As the median Bromage score reached 0 (no motor blockade), the mean±SD motor power recoveries at the knee, hip, and ankle were 28.2%±16%, 45.5%±24%, and 56.3%±28 %, respectively, and only 6 of 20 patients (30%, 95% confidence interval 10%-53%) were able to walk unassisted. After 75 minutes passed, 90% of the patients (95% confidence interval 56%-99%) were able to walk unassisted with mean motor power recovery of 63.6%±20%, 82.1%±27%, and 90.2%±24% at the knee, hip, and ankle, respectively. The area under the receiver operating characteristic curves was significantly higher with isometric contraction at different joints than the Bromage score (P<0.001). In addition, isometric contraction at different joints was effective in predicting the patients' ability to walk unassisted after subarachnoid block with prediction probabilities of 0.901, 0.948, and 0.958 for the knee, hip, and ankle, respectively, as compared with 0.752 for the Bromage score (P<0.001)., Conclusion: Quantitative measurement of the degree of recovery of the motor power of the knee, hip, or ankle flexors is more accurate and superior to the qualitative Bromage score, as a predictor of the patient's ability to safely ambulate after spinal anesthesia. This may be recommended when assessing motor block when small-dose anesthetic solutions are used.

Introduction: A case of cefepime-induced nonconvulsive status epilepticus in a 15-year-old child with end stage renal disease on hemodialysis is reported. Clinical symptoms and EEG dramatically improved 48 h after discontinuation of cefepime., Methods: Twenty-five cases of nonconvulsive status epilepticus associated with cefepime that have been reported in the literature are reviewed., Results: The average age was 60 years [15-86], our patient is the second pediatric patient reported, and 56% of cases occurred in women. The cefepime dosage was adjusted to the renal function in 5 cases. All except 1 patient have impaired renal function (CRF: 17 cases, ARF: 7 cases). The symptoms start 1-15 days after starting cefepime, mean 6 days. The outcome was good after discontinuation of cefepime therapy and anticonvulsant treatment, but lethal outcome was also reported in 2 cases. One fatality was related to status epilepticus., Conclusion: The clinicians' awareness must be increased about cefepime-induced nonconvulsive status epilepticus.