(E,E)-N1,N2-Bis(2,6-di­fluoro­benzyl­idene)ethane-1,2-di­amine.

The asymmetric unit of the title compound, C16H12F4N2, comprises half of the potentially bidentate Schiff base ligand, with an inversion centre located at the mid-point of the central C—C bond. The crystal packing is stabilized by inter­molecular C—H⋯N and π–π inter­actions [centroid–centroid distance = 3.6793 (12) Å and inter­planar spacing = 3.4999 (7) Å]

Yet Another Compressed Cache: a Low Cost Yet Effective Compressed Cache

Cache memories play a critical role in bridging the latency, bandwidth, and energy gaps between cores and off-chip memory. However, caches frequently consume a significant fraction of a multicore chip’s area, and thus account for a significant fraction of its cost. Compression has the potential to improve the effective capacity of a cache, providing the performance and energy benefits of a larger cache while using less area. The design of a compressed cache must address two important issues: i) a low-latency, low-overhead compression algorithm that can represent a fixed-size cache block using fewer bits and ii) a cache organization that can efficiently store the resulting variable-size compressed blocks. This paper focuses on the latter issue. In this paper, we propose YACC (Yet Another Compressed Cache), a new compressed cache design that uses super-blocks to reduce tag overheads and variable-size blocks to reduce internal fragmentation, but eliminates two major sources of complexity in previous work—decoupled tag-data mapping and address skewing. YACC’s cache layout is similar to conventional caches, eliminating the back-pointers used to maintain a decoupled tag-data mapping and the extra decoders used to implement skewed associativity. An additional advantage of YACC is that it enables modern replacement mechanisms, such as RRIP. For our benchmark set, YACC performs comparably to the recently-proposed Skewed Compressed Cache (SCC) ‎[Sardashti et al. 2014], but with a simpler, more area efficient design without the complexity and overheads of skewing. Compared to a conventional uncompressed 8MB LLC, YACC improves performance by on average 8% and up to 26%, and reduces total energy by on average 6% and up to 20%. An 8MB YACC achieves approximately the same performance and energy improvements as a 16MB conventional cache at a much smaller silicon footprint, with 1.6% higher area than an 8MB conventional cach

Use of Paracetamol and Ibuprofen in Combination for Pain Relief in Children after Oral Surgery

The aim of this study was to determine the use of paracetamol and ibuprofen in combination for pain relief in children after oral surgery. Children under 10 years old having one or more wisdom teeth removed under general or local anaesthesia were instructed to take two tablets before the operation then, every 4 h for up to 48 h, two tablets of a combination of acetaminophen 250 mg and ibuprofen 150 mg per tablet and acetaminophen 250 mg per tablet alone and ibuprofen 150 mg per tablet alone. The primary outcome measure was the area under the curve of the 100 mm visual analogue scale of pain measurements taken for up to 36 h after surgery, divided by time, at rest and in activity. The result showed that although all four secondary endpoints favoured the combination treatment, only the global pain rating reached statistical significance. More participants experienced ‘nil’ or ‘mild’ pain with the combination (68.4%) than with either other group; this difference was significant for acetaminophen (37.5%; P=0.008), but not for ibuprofen (54.3%; P=0.263). The use of any rescue medication also favoured the combination treatment, but this did not reach statistical significance. In conclusion, we demonstrated that patients using the combination of acetaminophen and ibuprofen experienced less pain during the first 48 h after oral surgery than those using the same daily dosage of either agent alone and we think the difference was clinically relevant

Methodologies for Obtaining Reliable Indicators for the Environmental Stress Cracking Resistance of Polyethylene

Environmental stress cracking (ESC) is one of the main, and probably the most common, failure mechanisms involved in polymer fractures. This type of failure is critically important as it occurs suddenly, without any visible pre-fracture deformation. Such failure can be catastrophic and costly in cases where structural integrity is required. In polyethylene (PE), ESC occurs through a slow crack growth mechanism. Cracks initiate from stress-concentrated imperfections, propagate through the bulk of PE, and ultimately result in a brittle fracture. In order to predict the environmental stress cracking resistance (ESCR) of PE, it is necessary to fully understand the molecular structure of the resin. In this thesis, attempts were made to find relationships between molecular structure characteristics and material responses, mainly inter-lamellar entanglements and strain hardening behaviour of PE resins, through mechanical and rheological experiments. Inter-lamellar entanglements are believed to be the main factor controlling slow crack growth of PE. Extent of entanglements and entanglement efficiency were investigated by monitoring the strain hardening behaviour of PE resins in the solid state through a uniaxial tensile test, and in the melt state, through extensional rheometry. ESCR is usually assessed by unreliable and time consuming testing methods such as the notch constant load test (NCLT) on notched PE specimens in the presence of an aggressive fluid and elevated temperatures. In this thesis, a practical, yet reliable, tensile test was developed for the evaluation and prediction of ESCR. The developed test offers a more reliable and consistent ESCR picture without the drawbacks of the subjective notching process and presence of aggressive fluids. Through this test, a factor called “corrected hardening stiffness (cHS)” was developed, which can easily be used for a relative ranking of ESCR of different PE resins. Studies were next extended to the melt state via shear and extensional rheometry. Through studies in the shear mode, a molecular weight-normalized average characteristic relaxation time (λN) was found to be efficient in predicting the extent of chain entanglements in resins. This provided a potential melt indicator for a relative measure of ESCR, for linear low density polyethylene (LLDPE), with different short chain branching levels. Extensional studies were conducted to evaluate the strain hardening behaviour in the melt state. An inverse correlation was obtained between ESCR and the melt strain hardening coefficient (MSHC), found from Sentmanat Extensional Rheometry (SER). This indicated an inverse relationship between ESCR and chain extensibility in the melt. In addition, a new factor called “melt hardening stiffness (mHS)” was developed from the slope of a stress-strain line, obtained from SER. This factor, analogous to cHS, can be used for a practical and reliable ranking of ESCR of PEs. ESCR is usually associated with classical crystalline phase property indicators, such as crystallinity and lamella thickness. In this thesis, the effect of processing and post processing temperature on the extent of inter-lamellar entanglements were investigated, evaluated, and correlated to ESCR. Also, analysis of the lamella surface area (LSA) was pursued since LSA reflects changes in phase interconnectivity more precisely. The focus of this part of the study was on the effect of temperature on LSA to identify the optimum processing and post-processing conditions which yield a higher LSA. It was reasonable to presume that PE with larger lamella lateral surface areas will have more inter-lamellar entanglements, hence higher ESCR. Finally, a well-controlled ultraviolet (UV) photoinitiated reactive extrusion (REX) process was developed for selective formation of long chain branches in the PE structure. This was conducted to impose restrictions against stretching of the polymer chain, which consequently enhanced ESCR

Wheat Straw-Clay-Polypropylene Hybrid Composites

The preparation of polymeric hybrid composite consisting of organic and inorganic fillers is of interest for industries like automotive, construction and packaging. In order to understand and predict the physical and chemical properties of these hybrid composites, it is necessary to fully understand the nature and properties of the employed fillers. In this study, the preparation of polypropylene hybrid composite consisting of wheat straw and clay was investigated. A detailed study was performed on wheat straw from South Western Ontario region. The effect of grinding the straw and compounding it with polypropylene was investigated. Experiments were carried out to identify the thermal stability of the ground wheat straw with respect to their size and composition. It was important to identify a correlation between these properties in order to minimize the straw degradation by processing and also to improve the final properties of the hybrid composite. The composite samples were prepared through melt blending method using a co-rotating twin-screw extruder. Sample test bars were prepared by injection moulding. The composition of the constituents of the hybrid composite; percentages of wheat straw, clay and coupling agent, were varied in order to investigate their influence on thermal stability, water resistance and mechanical properties. The results of the study indicated that grinding the wheat straw with a hammer mill produced particles with different sizes and shapes. It was found that through the grinding system all particles, regardless of their size, had a multi-layered structure similar to the plant structure. Further hammer milling did not produce plant particles with long aspect ratios that would be expected in a defibrillation process. Analysis of the chemical composition of wheat straw particles of different sizes and shapes was used to measure the ratio of hemicelluloses: lignin and the ash content. It was found that the large particles contained more amount of lignin whereas smaller particles had larger amount of ash content. The thermal stability of the particles was found to be a function of particle size rather than the lignin content. Particle size analysis on the wheat straw particles after the extrusion process indicated a reduction in the particle length and aspect ratio. The thermal stability of the composites was found to be enhanced by the addition of clay particles at higher temperature and the addition of coupling agent at lower temperatures. Increasing the amount of wheat straw and clay content increased the flexural modulus and reduced the resistance for water absorption. Increasing the amount of coupling agent also increased the flexural modulus and resistance for water absorption. The morphological study by scanning electron microscopy revealed that coupling agent increased the interfacial interaction between the particles and the polymer matrix

Kinetic study of H-terminated silicon nanowires oxidation in very first stages

Oxidation of silicon nanowires (Si NWs) is an undesirable phenomenon that has a detrimental effect on their electronic properties. To prevent oxidation of Si NWs, a deeper understanding of the oxidation reaction kinetics is necessary. In the current work, we study the oxidation kinetics of hydrogen- terminated Si NWs (H-Si NWs) as the starting surfaces for molecular functionalization of Si surfaces. H-Si NWs of 85-nm average diameter were annealed at various temperatures from 50°C to 400°C, in short-time spans ranging from 5 to 60 min. At high temperatures (T ≥ 200°C), oxidation was found to be dominated by the oxide growth site formation (made up of silicon suboxides) and subsequent silicon oxide self-limitation. Si-Si backbond oxidation and Si-H surface bond propagation dominated the process at lower temperatures (T < 200°C)

Evaluation of the Relationship Between Reflux Esophagitis and Helicobacter Pylori Stomach Infection in Patients Referring to Zahedan Hospitals, Sistan and Baluchistan Province, Iran

Gastro-oesophageal reflux disease is a common disorder of the digestive tract. Exposure of the oesophageal mucosa to gastric acid can lead to mucosal damage as in oesophagitis. The aim of this study was to determine the relationship between Helicobacter pylori infection in the stomach and reflux oesophagitis in patients, referring to the endoscopy units of hospitals in Zahedan between 2015 and 2019. In this cross-sectional study, all patients (under 15, 15-25, 25-35, 35-45 and 45 years and older) who referred to the Endoscopy units of two randomly selected hospitals in Zahedan during 2015-2019, were studied. H. pylori infection was diagnosed from pathological specimens. Information on all patients, including age, sex, presence of oesophagitis and its grade, and H. pylori infection was recorded on questionnaires and their relationships with oesophagitis and its grade as well as H. pylori infection were analyzed statistically. Tables and charts were used to illustrate the data. T-tests and Chi-squared tests were used to investigate the relationships between variables. The results showed that the frequency of oesophagitis in our patients was 52.8%, with the highest frequency being obtained for grade B oesophagitis (48%). In this study, the prevalence of H. pylori infection was 57.5%. This rate was 55.4% in patients with oesophagitis, with a statistically significant difference from the group without oesophagitis. There was a significant relationship between grade A oesophagitis and H. pylori infection. In conclusion, we were able to demonstrate a significant relationship between H. pylori infection and oesophagitis in affected patients

Effect of hope therapy on the hope of diabetic patients

Hope is the most important factor in diabetic patients' life. The level of hope may be changing among these individuals as a result of chronic nature of diabetes and its complications. When the level of hope increases among these patients, they can resist against physical and psychological complications of diabetes more, accept the treatment better, enjoy life more, and adapt with their situations more efficiently. This study aimed to define the efficacy of hope therapy on hope among diabetic patients. This was a quasi-experimental study conducted on 38 diabetic patients referring to Sedigheh Tahereh Research and Treatment Center affiliated to Isfahan University of Medical Sciences in Iran in 2012. The subjects were selected based on the goals and inclusion criteria of the study and then were randomly assigned to study and control groups. Herth Hope Index (HHI) was completed by both groups before, after, and 1 month after intervention. In the study group, 120-min sessions of hope therapy were held twice a week for 4 weeks. Descriptive and inferential statistical tests were adopted to analyze the data through SPSS version 12. Comparison of the results showed that hope therapy significantly increased hope in diabetic patients after intervention in the study group compared to control (P < 0.001). The results showed that hope therapy increased hope among diabetic patients. This method is suggested to be conducted for diabetic patients. Effect of hope therapy on the hope of diabetic patients (PDF Download Available). Available from: https://www.researchgate.net/publication/272842885_Effect_of_hope_therapy_on_the_hope_of_diabetic_patients [accessed Oct 28 2017]

Critical Pedagogy in Architectural Design Course (case study: postgraduate design course (1) of Islamic Azad university of Gorgan)

Background and Objective:Creating a learning environment rich in social relationships in which peer interaction and collective learning can be developed is the core of the studio-based education for teaching architectural design. The social dimensions of the studio and the opportunities it provides for collaboration and participation serve as a stimulus for learning, and it is the culture of the studio that means sustainability to students. One of the interactive teaching methods that seems to be in line with the multiplicity of today's world and the different nature of architecture and the workshop education system is the critical pedagogy method invented by the Brazilian thinker Paolo Freire. Freire considers the main purpose of education to be the development of creative and critical human beings who look critically at all the thoughts, ideas and values ​​in society, as well as the actions of individuals and the way they deal with various events and happenings to find their roots. Freire's model in critical education mostly includes critical dialogue in which students (whole class) present their views and review evaluations and critiques. Participate in evaluating the thoughts of others and together with them, by combining views and examining arguments, take a more accurate and comprehensive approach to the issue and discover effective solutions. Therefore, it can be inferred that the critical education methodwith its special characteristics has the potential to improve the quality of architectural design classes. The aim of this study is to illustrate the procedure of applying critical pedagogy in Iran higher education context –architecture discipline- to identify challenges and improve the method in the selected environment. Methods:The qualitative method (interpretation) was selected as research method and content analysis was performed on the collected data. 24 postgraduate architecture students were selected as the sample, and by using a bipartite subject, comparison between two methods (traditional and critical) become possible. To verify and extend the model, the experiment was repeated next year with 22 different students. Findings: The results indicated that the effects of critical pedagogy have been perceived by students in eight categories: (1) improving intrinsic motivation (2) improving social skills, oral skills and self-confidence, (3) improving the speed and quality of development process of architectural ideas, (4) creating diversity and cheerfulness, (5) reducing stress and anxiety, (6) waste of time and vain discussions, (7) educational marginalization, and (8) self-censorship. The first 5 categories are positive feedbacks and the other three are negative feedbacks considered as challenges of applying critical pedagogy. At the end, some strategies are purposed to overcome these challenges and improve the quality of the classes. Conclusion:Some solutions to overcome the challenges are suggested including: students choosing an external reality topic, phasing group corrections, continuing the method to institutionalize it, changing students' view of the teacher as the source of information or the professor as a superior and miraculous person and change the view and reduce students' distrust of themselves. Characteristics for the critical teacher are also mentioned, such as humility, humor, high capacity of the teacher against laughter and jokes, great patience of the teacher in the face of useless discussions, and familiarity of the critical teacher with theories of psychology and psychoanalysis.   ===================================================================================== COPYRIGHTS  ©2019 The author(s). This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, as long as the original authors and source are cited. No permission is required from the authors or the publishers.  ====================================================================================

One-dimensional Modelling and Optimisation of an Industrial Steam Methane Reformer

Steam methane reforming is one of the most promising processes to convert natural gas into valuable products such as hydrogen. In this study, a one-dimensional model was used to model and optimise an industrial steam methane reformer, using mass and thermal balances coupled with pressure drop in the reformer tube. The proposed model was validated by the experimental data. Furthermore, the effects of flowrate and temperature of the feed, tube wall temperature, and tube dimension on the reformer performance were studied. Finally, a multiobjective optimisation was done for methane slip minimisation and hydrogen production maximisation using genetic algorithm. The results illustrated the optimum feed flowrate of 2761.9 kmol h–1 (minimum 32 mol.% produced hydrogen and maximum 0.15 mol.% unreacted methane). This is one of the few studies on investigation of steam methane reformer using a simple and effective model, and genetic algorithm. This work is licensed under a Creative Commons Attribution 4.0 International License