Experimental and theoretical investigation of the fluid behavior during polymeric fiber formation with and without pressure

The fabrication of polymeric micro/nanofibers is gaining attention due to their use in an array of applications including tissue engineering scaffolds, nanosensors, and fiber-reinforced composites. Despite their versatile nature, polymeric fibers are widely underutilized due to the lack of reliable, large-scale production techniques. Upon the discovery of centrifugal spinning and, recently, pressurized gyration techniques, new research directions have emerged. Here, we report a comprehensive study detailing the optimal conditions to significantly improve the morphology, homogeneity, and yield of fibers of varying diameters. A series of polymeric fibers was created using a 21 wt. % solution of polyethylene oxide in distilled water and the fluid behavior was monitored inside a transparent reservoir using a high-speed camera. Fabrication of the fibers took less than 1 s. Using centrifugal spinning, we studied the formation of the fibers at three different rotational speeds, and for pressurized gyration, one rotational speed was studied with three different nitrogen gas pressures. Using the pressurized gyration technique at a gas pressure of 0.3 MPa, there was significant improvement in the production yield of the fibers. We found a strong correlation between the variation of pressure and the rate of the solution leaving the reservoir with the improved morphology of the fibers. The use of reduced power techniques, like centrifugal spinning and pressured gyration, to yield high-quality nonwoven nanofibers and microfibers in large quantities is important due to their use in rapidly expanding markets

Core–sheath polymer nanofiber formation by the simultaneous application of rotation and pressure in a novel purpose-designed vessel

Forming polymeric core–sheath nanofibers is gaining prominence owing to their numerous potential applications, most notably in functional scenarios such as antiviral filtration, which is attracting significant attention due to the current COVID pandemic. This study has successfully designed and constructed a novel pressurized gyration vessel to fabricate core–sheath polymer nanofibers. Several water-soluble and water-insoluble polymer combinations are investigated. Both polyethylene oxide and polyvinyl alcohol were used as the core while both poly(lactic acid) (PLA) and poly(caprolactone) (PCL) were used as the sheath; PLA and PCL were used as core and sheath, in different instances; respectively. The fluid behavior of the core–sheath within the vessel was studied with and without applied pressure using computational fluid dynamics to simulate the core–sheath flow within the chamber. A high-speed camera was used to observe the behavior of jetted solutions at core–sheath openings, and the best scenario was achieved using 6000 rpm spinning speed with 0.2 MPa (twice atmospheric) applied pressure. The surface morphology of core–sheath fibers was studied using a scanning electron microscope, and focused ion beam milling assisted scanning electron microscopy was used to investigate the cross-sectional features of the produced fibers. Laser confocal scanning microscopy was also used to verify the core–sheath structure of the fibers, which were further characterized by Fourier transform infrared spectroscopy and differential scanning calorimetry. Thus, using a variety of polymer combinations, we show, both theoretically and experimentally, how core–sheath fibers evolve in a vessel that can serve as a scalable manufacturing pressurized gyration production process

A novel reusable anti-COVID-19 transparent face respirator with optimized airflow

This novel face mask is designed to be a reusable respirator with a small and highly efficient disposable fabric filter. Respirator material requirements are reduced by 75% compared to traditional designs and allow repeated cleaning or sterilization. The probability of virus particle inhalation is reduced using novel air filtration pathways, through square-waveform design to increase filter airflow. Air enters the mask from right and left side filters, while the area in front of the mouth is isolated. Clear epoxy is used for a transparent frame, allowing lip-reading, and mask edges contain a silicone seal preventing bypass of the filters. The mask is manufactured using silicone molds, eliminating electricity requirements making it economical and viable in developing countries. Computational fluid dynamics numerical studies and Fluent ANSYS software were used to simulate airflow through the filter to optimize filter air path geometry and validate mask design with realistic human requirements. The breathing cycle was represented as a transient function, and N95 filter specifications were selected as a porous medium. The novel design achieved 1.2 × 10-3 kg s-1, 20% higher than human requirements, with air streamlines velocity indicating local high speed, forcing and trapping virus particles against filter walls through centrifugal forces

Perspective: Covid-19; emerging strategies and material technologies

It will be remembered in history as the event that brought the world together with science and technology; the COVID-19 pandemic has allowed for decades worth of progression in both healthcare policies and technology development. It has been a show of unprecedented global health policies ranging from the legal requirement for public facemask use to the use of tough movement restrictions that has bought the world's economy to its knees. Here, we observe the impact of national lockdowns, facemask usage, and their effect on infection rates. It is clear that healthcare policies alone cannot tackle a pandemic. There is a huge pressure to develop personal protective equipment that not only has the capacity to prevent transmission but also has the ergonomics to be worn for long durations. In this work, we reveal our views and thoughts on the healthcare policies and developing materials and technology strategies that have contributed to reduce the damage of the pandemic, coming from the perspectives of materials scientists and a UK National Health Service consultant doctor

Optimization of Process-Control Parameters for the Diameter of Electrospun Hydrophilic Polymeric Composite Nanofibers

A composite nanofiber composed of three polymers, namely polyvinyl alcohol/polyvinyl pyrrolidone/polyethylene oxide, is produced. The experiments are constructed using three design of experiment techniques, Taguchi L9, Taguchi L27, and Screening method. The experiments are verified using the analysis of variance (ANOVA) method and later a mathematical model is developed using the regression method. The impact of electrospun processing parameters, namely applied voltage, flow rate, and working distance, on nanofibers' diameter is measured. The working distance is a significant factor in controlling the size of the fiber diameter, while the applied voltage has the lowest effect on it. As a result of the regression equation, a Genetic algorithm is used to find the optimum variables for the required fiber diameter, which is 156 nm for flow rate = 0.001 mL h−1, voltage = 30 kV, and distance = 200 mm with a 3% difference from the experimental fiber diameter

Adaptive Control of IoT/M2M Devices in Smart Buildings using Heterogeneous Wireless Networks

With the rapid development of wireless communication technology, the Internet of Things (IoT) and Machine-to-Machine (M2M) are becoming essential for many applications. One of the most emblematic IoT/M2M applications is smart buildings. The current Building Automation Systems (BAS) are limited by many factors, including the lack of integration of IoT and M2M technologies, unfriendly user interfacing, and the lack of a convergent solution. Therefore, this paper proposes a better approach of using heterogeneous wireless networks consisting of Wireless Sensor Networks (WSNs) and Mobile Cellular Networks (MCNs) for IoT/M2M smart building systems. One of the most significant outcomes of this research is to provide accurate readings to the server, and very low latency, through which users can easily control and monitor remotely the proposed system that consists of several innovative services, namely smart parking, garden irrigation automation, intrusion alarm, smart door, fire and gas detection, smart lighting, smart medication reminder, and indoor air quality monitoring. All these services are designed and implemented to control and monitor from afar the building via our free mobile application named Raniso which is a local server that allows remote control of the building. This IoT/M2M smart building system is customizable to meet the needs of users, improving safety and quality of life while reducing energy consumption. Additionally, it helps prevent the loss of resources and human lives by detecting and managing risks.Comment: Accepted in IEEE Sensors Journa

Knowledge and Awareness of Diabetes Mellitus Disease among High School Students in King Abdulaziz Military City, Tabuk, Saudi Arabia

BACKGROUND: Saudi Arabia is considered to be one of the highest countries in the Middle East for the incidence of diabetes mellitus (DM). Data are lacking regarding knowledge and awareness about DM among school students in Saudi Arabia. AIM: The study aimed to assess the level of knowledge and awareness of DM among high school students within the military city, Tabuk, Saudi Arabia. METHODS: A descriptive type of cross-sectional study was conducted among 278 high school students applying a convenience sampling technique. The sample size was calculated using OpenEpi, Version 3. Self-administered questionnaires were distributed to the high school students (male and female) after official communication with the school’s dean. The level of knowledge and awareness was categorized into “adequate” and “inadequate” as per each topic/question, and also as per each response/answer. Data entry and analysis were carried out using the Statistical Package for the Social Sciences. Pearson’s Chi-square tests were performed to explore if there is any significant association between the knowledge and awareness level of the high school students and their (i) gender, (ii) age, and (iii) level of education. RESULTS: More than half of the high school students had adequate level of knowledge and awareness about DM in terms of symptoms (67.3%), complications (56.5%), monitoring method (62.6%), lifestyle modifications (63.7%), frequency of routine eye check-up (63.3%), important factors for blood sugar control (79.1%), treatment (56.5%), and management of hypoglycemia symptoms (57.6%). On the contrary, a large number of the students showed inadequate level of knowledge and awareness about the disease in terms of definition (80.6%), major causes (57.9%), effect of high blood pressure (51.8%), frequency of routine blood pressure check-up (55%), rationale of a regular urine test (58.3%), medication for DM (66.9%), and duration of medication (69.8%). However, no significant associations were found between the knowledge and awareness level of the high school students about the definition or major causes of DM and the (i) gender, (ii) age group, and (iii) level of education of the students. CONCLUSION: The level of knowledge and awareness of a considerable number of high school students regarding DM was inadequate, and some of them possessed various misconceptions about this particular chronic disease. Health authorities and school authorities in the region should offer special efforts to improve the level of knowledge and awareness of the students through regular health education campaigns

Microbiological analysis of root canal infections using high throughput sequencing on the Illumina MiSeq platform

Aim: To investigate the microbial diversity of primary and secondary root canal infections using high throughput sequencing on the illumina MiSeq and culture methods. Methods: 19 subjects were recruited for the study; ten primary infections and nine secondary infections. Samples were collected before chemo-mechanical preparation (S1) and prior to obturation (S2), respectively. Microbiological culture aliquots were serially diluted and inoculated onto various non selective and selective media for total anaerobic and total aerobic counts. For high throughput sequencing, DNA was extracted and the V3/V4 region of the 16SrRNA gene was amplified using the 347F/803R primers, sequenced using the Illumina MiSeq instrument. Raw data were analysed using an open-source bioinformatics pipeline called quantitative insights into microbial ecology (QIIME). Results: Culture: Total anaerobic counts from primary infections ranged from 1.7 X10^1- 7.9 X10^6 colony forming units (cfu)/ml (mean log10 cfu/ml ± SD: 3.08 ± 1.51), whilst total aerobic counts ranged from 3 X10^3- 4.17 X10^5 cfu/ml ( mean log10 cfu/ml ± SD:3.09 ± 1.72). The quantity of microorganisms recovered from secondary infections ranged from 3 X10^2- 4.9 X10^3 cfu/ml (mean log10 cfu/ml ± SD: 2.81 ± 0.78) and from 2.7 X10^2- 8 X10^5 (mean log10 cfu/ml ± SD: 2.60 ± 1.48) with regard to total anaerobic and total aerobic viable counts, respectively. Sequencing analysis yielded partial 16S rRNA gene sequences that were taxonomically classified into 10 phyla and 143 genera. The most represented phyla in the total sample were Firmicutes, Proteobacteria, Actinobacteria, Bacteroidetes, Synergistetes and Fusobacteria. The most dominant genera in primary S1 samples were Streptococcus, Bacillaceae and Eubacterium while Alkalibacterium, Bacillaceae and TG5 dominated the secondary infections. The majority of genera occurred at low levels. The mean number (± SD) of species-level phylotypes per canal was 63 (±14.9; range 34– 80), and 69.9 (± 12.0; range 50 – 87) in primary and secondary infections (S1) samples, respectively. A great inter-individual variation in the composition of the root canal microbiota was observed. Conclusions: The study demonstrated the extensive diversity of the bacterial communities present in root canal infections although the majority of the taxa detected were in low abundance. The study indicates that secondary infections seem more diverse than previously anticipated

Effects of mist fractions on heat transfer characteristics in a rotating roughened cooling passage

This paper investigates the effects of the mist fractions on heat transfer characteristics applied on a rotating U-channel with inclined ribs at an angle of 45°. This study has been conducted on five different mist percentages from 1 to 5 with a 1% increment at each step, and all of the cases have been investigated for Reynolds number values of 5000, 10000, 25000 and 40000. The numerical results obtained from the application of RNG k-ε turbulence model with enhanced-wall function were in good agreement with the experimental data of the smooth and ribbed channels both with and without mist addition. Results also demonstrated a 300% increase in the flow temperature difference and a noticeable increase in Nusselt number at each bend region and at the downstream of the leading edge around 25% and 110% respectively, at high mist fraction (5%); when compared with the case where only air was used. With %5 mist addition, the convective efficiency also reaches approximately 69%

Flow structure and heat transfer of jet impingement on a rib-roughened flat plate

The jet impingement technique is an effective method to achieve a high heat transfer rate and is widely used in industry. Enhancing the heat transfer rate even minimally will improve the performance of many engineering systems and applications. In this numerical study, the convective heat transfer process between orthogonal air jet impingement on a smooth, horizontal surface and a roughened uniformly heated flat plate is studied. The roughness element takes the form of a circular rib of square cross-section positioned at different radii around the stagnation point. At each location, the effect of the roughness element on heat transfer rate was simulated for six different heights and the optimum rib location and rib dimension determined. The average Nusselt number has been evaluated within and beyond the stagnation region to better quantify the heat transfer advantages of ribbed surfaces over smooth surfaces. The results showed both flow and heat transfer features vary significantly with rib dimension and location on the heated surface. This variation in the streamwise direction included both augmentation and decrease in heat transfer rate when compared to the baseline no-rib case. The enhancement in normalized averaged Nusselt number obtained by placing the rib at the most optimum radial location R/D = 2 was 15.6% compared to the baseline case. It was also found that the maximum average Nusselt number for each location was achieved when the rib height was close to the corresponding boundary layer thickness of the smooth surface at the same rib position