ABSTRACT
Nanofluids have opened the doors towards the enhancement of many of today's existing thermal applications performance. This is because these advanced working fluids exhibit exceptional thermophysical properties, and thus making them excellent candidates for replacing conventional working fluids. On the other hand, nanomaterials of carbon-base were proven throughout the literature to have the highest thermal conductivity among all other types of nanoscaled materials. Therefore, when these materials are homogeneously dispersed in a base fluid, the resulting suspension will theoretically attain orders of magnitude higher effective thermal conductivity than its counterpart. Despite this fact, there are still some challenges that are associated with these types of fluids. The main obstacle is the dispersion stability of the nanomaterials, which can lead the attractive properties of the nanofluid to degrade with time, up to the point where they lose their effectiveness. For such reason, this work has been devoted towards providing a systematic review on nanofluids of carbon-base, precisely; carbon nanotubes, graphene, and nanodiamonds, and their employment in thermal systems commonly used in the energy sectors. Firstly, this work reviews the synthesis approaches of the carbon-based feedstock. Then, it explains the different nanofluids fabrication methods. The dispersion stability is also discussed in terms of measuring techniques, enhancement methods, and its effect on the suspension thermophysical properties. The study summarizes the development in the correlations used to predict the thermophysical properties of the dispersion. Furthermore, it assesses the influence of these advanced working fluids on parabolic trough solar collectors, nuclear reactor systems, and air conditioning and refrigeration systems. Lastly, the current gap in scientific knowledge is provided to set up future research directions.
ABSTRACT
OBJECTIVES: This study intended to understand the risk of developing temporomandibular disorder among Saudi women who experienced a miscarriage. MATERIALS AND METHODS: Two hundred and eight Saudi women from several hospitals' gynecologic clinics in two areas in Saudi Arabia were screened to fill out the Impact of Events Scale-Revised (self-reporting questionnaire) Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition diagnostic criteria for posttraumatic stress disorder and a structured temporomandibular joint disorder (TMD) Questionnaire (Research Diagnostic Criteria for Temporomandibular Disorders). A single examiner did the clinical examination for temporomandibular joint (TMJ). One-hundred and fifty-eight of the participants were divided into two groups. Group A (85 participants) included females who had had a previous miscarriage, whereas Group B (73 participants) included females who had not had a miscarriage. IBM SPSS version 22.0 was used to conduct a nonparametric Chi-square test to find the significance of any observed differences. RESULTS: Almost 40% of the participants had symptoms that qualified for possible TMD. Around 73% of the miscarried Saudi women in Group A showed symptoms of TMD. Furthermore, approximately 38% of the participants in Group B developed significant symptoms of TMD. The Chi-square test (Chi-test = 22.03 with P = 0.0001) shows highly significant association between treatment groups (control and study) and temporomandibular joint disorder group and non temporomandibular joint disorder group. CONCLUSION: Women who suffer from spontaneous single or recurrent miscarriages are advised to seek a dental specialist for diagnosis and prevention devices such as a night guard.
ABSTRACT
INTRODUCTION: Chlorhexidine (CHX) is generally used as the final irrigating solution in root canal therapy. Recent studies have reported that, toxic precipitates containing parachloroaniline (PCA) are formed when CHX reacts with sodium hypochlorite (NaOCl). Whereas, Alexidine (ALX), a bisbiguanide disinfectant similar to CHX, has proven to form no precipitates with NaOCl. AIM: To compare antimicrobial activity of different concentrations of ALX with CHX individually and when combined with NaOCl against E. faecalis strains. MATERIALS AND METHODS: Different concentrations of ALX and CHX (0.5%, 1%, and 2%) were tested individually and when mixed with 2.5% NaOCl (1:1 ratio) using disc diffusion method against E. faecalis. After 24 hours incubation at 37°C, zones of inhibition were measured for each solution. The results obtained were statistically analysed using one way ANOVA and Scheffe's post-hoc tests. The p-value <0.001 was considered as highly significant. RESULTS: Regardless of the concentrations, ALX obtained the best results in comparison to CHX. There was no statistically significant difference between ALX + NaOCl and CHX + NaOCl mixtures. CONCLUSION: The present study showed that, the antimicrobial property of ALX against E. faecalis was found to be superior to CHX at same concentrations.
