ABSTRACT
Over the past few decades, the field of organic electronics has depicted proliferated growth, due to the advantageous characteristics of organic semiconductors, such as tunability through synthetic chemistry, simplicity in processing, cost-effectiveness, and low-voltage operation, to cite a few. Organic electrochemical transistors (OECTs) have recently emerged as a highly promising technology in the area of biosensing and flexible electronics. OECT-based biosensors are capable of sensing brain activities, tissues, monitoring cells, hormones, DNAs, and glucose. Sensitivity, selectivity, and detection limit are the key parameters adopted for measuring the performance of OECT-based biosensors. This article highlights the advancements and exciting prospects of OECTs for future biosensing applications, such as cell-based biosensing, chemical sensing, DNA/ribonucleic acid (RNA) sensing, glucose sensing, immune sensing, ion sensing, and pH sensing. OECT-based biosensors outperform other conventional biosensors because of their excellent biocompatibility, high transconductance, and mixed electronic-ionic conductivity. At present, OECTs are fabricated and characterized in millimeter and micrometer dimensions, and miniaturizing their dimensions to nanoscale is the key challenge for utilizing them in the field of nanobioelectronics, nanomedicine, and nanobiosensing.
ABSTRACT
The emergence of COVID-19 raised awareness in hygiene practices and reminded us of the harm that microbes bring to our health. Incorporating antibacterial agents in polymeric materials would allow us to combat lingering bacteria on surfaces that we often use. The utilization of composite filaments with antibacterial activity would allow us to employ better precautions in reducing contact with harmful bacteria. Antibacterial acrylonitrile‐butadiene‐styrene (ABS) nanocomposites were prepared by incorporating silver zirconium phosphate (AgZrP) nanoparticles via twin screw extruder. The ABS/AgZrP nanocomposite filament with 5 wt % and 20 wt% of AgZrP were synthesized and characterized with Differential scanning calorimetry (DSC), Thermogravimetric Analysis (TGA), X-ray diffraction analysis (XRD), and Fourier transform infrared spectroscopy (FTIR). DSC and XRD data denote an increase in the presence of crystalline regions as the AgZrP content is increased. TGA data indicate that the addition of AgZrP has no effect on the thermal stability of the material. FTIR data indicate a decrease in transmission at higher AgZrP loading. The decreasing trend in tensile properties of the 3D-printed neat and AgZrP-filled ABS may have been due to particle agglomeration acting as stress concentrators. Antibacterial activity assessment via disk diffusion test showed a zone of inhibition within the sample indicating that there is no bacterial growth both for Escherichia coli and Staphylococcus aureus. © 2023 Trans Tech Publications Ltd, Switzerland.
ABSTRACT
Since the COVID-19 outbreak, the use of disposable plastics has rapidly increased along with the amount of plastic waste. During fragmentation, microplastics and other chemical substances contained in plastics are released. These then enter humans through food which could be problematic considering their hazardous potential. Polystyrene (PS), which is widely used in disposable containers, releases large amounts of microplastics (MPs), but no studies have investigated the release mechanisms of PS-MPs and simultaneously exposed contaminants. Therefore, in this study, the effects of pH (3, 5, 7, and 9), temperature (20, 50, 80, and 100 °C), and exposure time (2, 4, 6, and 8 h) on MPs release were systematically examined. A quantitative/qualitative study of MPs and styrene monomers was performed using microscopy-equipped Fourier-transformed infrared spectroscopy and gas chromatography-mass spectrometry. The release of PS-MPs (36 items/container) and simultaneously exposed pollutants (SEP), such as ethylene glycol monooleate (EGM), was highest at pH 9, 100 °C, and 6 h, which was proportional to the test temperature and time. Under the same conditions, 2.58 µg/L of styrene monomer migrated to the liquid food simulants. The fragmentation was proceeded by oxidation/hydrolysis and accelerated by increased temperature and exposure time. The strong positive correlation between PS-MPs and SEPs releases at pH and temperature indicates that PS-MPs and SEPs follow the same release process. However, a strongly negative correlation between PS-MPs and styrene monomers at the exposed time shows that styrene migration does not follow the same release process, but does its partition coefficient.
ABSTRACT
Aim of the study. To evaluate the value of predictors of hemoadsorption clinical efficacy in patients with COVID-19. Materials and methods. This study analyzed the results of treatment of 62 patients with severe COVID-19 in the intensive care unit using selective hemoadsorption of cytokines. All patients with severe COVID-19 were admitted to the intensive care unit within 14 days from the disease onset were subdivided into two groups. Group 1 patients (n=32) received on a top of standard treatment the hemoperfusion (HP) procedure for 4 hours, for 2-3 days in a row, using a cytokine sorption column composed of mesoporous styrene-divinilbenzen copolymer matrix. Group 2 patients were not subjected to extracorporeal blood purification. All patients received IL-6 inhibitors at a baseline in accordance to the temporary guidelines. We evaluated factors of unfavorable outcomes by analyzing changes in biochemical markers of systemic inflammatory response and mortality rates in patients of both groups. Results. Initiation of HP later than 10 days from NCI onset (P < 0.001), length of stay in the ICU, extent of lung damage (P = 0.036) and the SOFA (Sequential Organ Failure Assessment) score (P = 0.009) were the most powerful predictors of unfavorable outcome. Levels of systemic inflammatory response markers (in-terleukin-6, CRP, D-dimer) in both groups did not significantly affect the survival rates and length of hospital stay (P > 0.05). HP group demonstrated better survival (P < 0.05). Mean hospital stay was 31 and 27 days, ICU stay - 11 and 8 days for Groups 1 and 2, respectively (P < 0.05). Conclusion. Treatment of severe COVID-19 patients with HP using novel domestic hemosorbent composed of styrene-divinilbenzen copolymer matrix resulted in decrease in CRP levels on the first day after application and, with early onset, contributed to a significant increase in survival and decreased hospital and ICU stay. Additional studies are warranted to clarify the optimal timing of the initiation of HP in severe COVID-19 patients.Copyright © 2023, V.A. Negovsky Research Institute of General Reanimatology. All rights reserved.
ABSTRACT
Aim of the study. To evaluate the value of predictors of hemoadsorption clinical efficacy in patients with COVID-19. Materials and methods. This study analyzed the results of treatment of 62 patients with severe COVID-19 in the intensive care unit using selective hemoadsorption of cytokines. All patients with severe COVID-19 were admitted to the intensive care unit within 14 days from the disease onset were subdivided into two groups. Group 1 patients (n=32) received on a top of standard treatment the hemoperfusion (HP) procedure for 4 hours, for 2-3 days in a row, using a cytokine sorption column composed of mesoporous styrene-divinilbenzen copolymer matrix. Group 2 patients were not subjected to extracorporeal blood purification. All patients received IL-6 inhibitors at a baseline in accordance to the temporary guidelines. We evaluated factors of unfavorable outcomes by analyzing changes in biochemical markers of systemic inflammatory response and mortality rates in patients of both groups. Results. Initiation of HP later than 10 days from NCI onset (P < 0.001), length of stay in the ICU, extent of lung damage (P = 0.036) and the SOFA (Sequential Organ Failure Assessment) score (P = 0.009) were the most powerful predictors of unfavorable outcome. Levels of systemic inflammatory response markers (in-terleukin-6, CRP, D-dimer) in both groups did not significantly affect the survival rates and length of hospital stay (P > 0.05). HP group demonstrated better survival (P < 0.05). Mean hospital stay was 31 and 27 days, ICU stay - 11 and 8 days for Groups 1 and 2, respectively (P < 0.05). Conclusion. Treatment of severe COVID-19 patients with HP using novel domestic hemosorbent composed of styrene-divinilbenzen copolymer matrix resulted in decrease in CRP levels on the first day after application and, with early onset, contributed to a significant increase in survival and decreased hospital and ICU stay. Additional studies are warranted to clarify the optimal timing of the initiation of HP in severe COVID-19 patients.Copyright © 2023, V.A. Negovsky Research Institute of General Reanimatology. All rights reserved.
ABSTRACT
In accordance with global economic prosperity, the frequencies of food delivery and takeout orders have been increasing. The pandemic life, specifically arising from COVID-19, rapidly expanded the food delivery service. Thus, the massive generation of disposable plastic food containers has become significant environmental problems. Establishing a sustainable disposal platform for plastic packaging waste (PPW) of food delivery containers has intrigued particular interest. To comprise this grand challenge, a reliable thermal disposable platform has been suggested in this study. From the pyrolysis process, a heterogeneous plastic mixture of PPW was converted into syngas and value-added hydrocarbons (HCs). PPW collected from five different restaurants consisted of polypropylene (36.9 wt%), polyethylene (10.5 wt%), polyethylene terephthalate (18.1 wt%), polystyrene (13.5 wt%), polyvinyl chloride (4.2 wt%), and other composites (16.8 wt%). Due to these compositional complexities, pyrolysis of PPW led to formations of a variety of benzene derivatives and aliphatic HCs. Adapting multi-stage pyrolysis, the different chemicals were converted into industrial chemicals (benzene, toluene, styrene, etc.). To selectively convert HCs into syngas (H2 and CO), catalytic pyrolysis was adapted using supported Ni catalyst (5 wt% Ni/SiO2). Over Ni catalyst, H2 was produced as a main product due to C[sbnd]H bond scission of HCs. When CO2 was used as a co-reactant, HCs were further transformed to H2 and CO through the chemical reactions of CO2 with gas phase HCs. CO2-assisted catalytic pyrolysis also retarded catalyst deactivation inhibiting coke deposition on Ni catalyst. © 2022 Elsevier B.V.
ABSTRACT
Designing a surface that can disinfect itself can reduce labor-intensive cleanings and harmful waste, and mitigate spread of surface borne diseases. Additionally, since COVID-19 is an airborne pathogen, surface modification of masks and filters could assist with infection control. Styrene-maleic acid (SMA) copolymers and their derivatives were shown to have lipid-bilayer disrupting properties, making them candidates as anti-viral materials. A series of network polymers with styrene-maleic acid-based polymers and control over polymer chain-length and composition were synthesized. All the polymers formed mechanically robust structures, with tunable Young's moduli on the order of MPa, and tunable swelling capability in water. The SMA-based bulk materials, containing a zwitterionic polar unit, showed excellent lipid disrupting properties, being up to 2 times more efficient than a 10% Triton solution. The highest performance was observed for materials with lower crosslink densities or shorter chain-lengths, with lipid disruption capability correlating with swelling ratio. Additionally, the material can capture the spike protein of SARS-CoV-2, with up to 90% efficiency. Both the lipid disrupting and spike protein capture ability could be repeated for multiple cycles. Finally, the materials are shown to modify various porous and non-porous substrates including surgical and KN95 masks. Functional network modified masks had up to 6 times higher bilayer disruption ability than the unmodified masks without inhibiting airflow. © 2022 The Royal Society of Chemistry.
ABSTRACT
The global situation caused by a coronavirus in 2020 has become an unprecedented health crisis. Since 1918, during the Spanish flu, Brazilian society haven’t seen a pandemic disease. Among the many individuals exposed to the virus, health care professionals are essential workers who fight the disease. However, due to the lack of previous investments in the public health sector in Brazil, several obstacles are evident, such as the reduced number of Personal Protective Equipment (PPE) available for healthcare professionals who have direct contact with those affected by the disease. Therefore, undergraduate students and professors from UFPA (Universidade Federal do Pará—Federal University of Pará) Biomedical Engineering program course mobilized to create solutions to this problem through the study and production of a low-cost face shield model, which proved to be essential in helping professionals, in addition to engaging several students in the social causes. Similar initiatives like this took place in states in southeastern Brazil, through the making of PPE in 3D printers from PLA (polylactic acid) or ABS (Acrylonitrile Butadiene Styrene) filaments, which can take hours to be ready. Therefore, the present study presents a handmade model to promote higher cost–benefit and shorter manufacturing time. To measure how this PPE proposed here affected the daily work of these professionals, this study performed a feedback form focused on the professionals who used the handmade model. Also, a comparison between the 3D printed versus the handmade model was done. The study showed that 69.5% of the respondents, which were professionals working in the health field, felt more protected with the handmade face shield. Finally, for this research, it is possible to say that the handmade faceshields have proven to be effective, providing confidence when used by the research participants. © 2022, Springer Nature Switzerland AG.
ABSTRACT
This paper presents the design of a small size Unmanned Aerial Vehicle (UAV) using the 3DEXPERIENCE software. The process of designing the frame parts involves many methods to ensure the parts can meet the requirements while conforming to safety and industry standards. The design steps start with the selection of materials that can be used for the drone, which are polylactic acid (PLA), acrylonitrile styrene acrylate (ASA), and acrylonitrile butadiene styrene (ABS). The drone frame consists of four main parts, which are the center top cover (50 g), the side top cover (10 g), the middle cover (30 g), and the drone’s arm (80 g). A simulation was carried out to determine the stress, displacement, and weight of the drone’s parts. Additionally, a trade-off study was conducted to finalize the shapes of the parts and the various inputs based on their priorities. The outcome of this new design can be represented in design concepts, which involve the use of the snap hook function to assemble two body parts together, namely the middle cover and the center top cover, without the need of an additional fastener.
ABSTRACT
In the wake of the SARS-CoV-2 pandemic, inactivating bioaerosols became a pivotal issue which helps to prevent the transmittance of SARS-CoV-2. Thus, the current study was conducted to investigate a potential inactivating method using both ozone (O-3) and ultraviolet C (UVC). Individual and integrated effects of O-3 and UVC were compared. A solution containing approximately 4 similar to 7.3 x 10(6) CFU/mL of Salmonella typhimurium bacteria was used to produce bacteria droplets. These droplets were exposed to O-3 and UVC to determine the reduction rate of bacteria. The exposure times were set as 1 and 30 minutes. Ozone concentrations were 100 and 200 ppmv. UVC-LEDs were used as a UVC source. Peak wavelength of the UVC-LED was 275 nm and the irradiation dose was 0.77 mW/cm(2). In terms of O-3 and UVC-LED interaction, 194 ppmv styrene was used as a target compound to be removed. Considering the O-3 and UVC-LED interaction, the presence of O-3 could reduce the performance of the UVC-LED, and UVC-LED could also reduce significant amount of O-3. The sequence of O-3 and UVC-LED treatment was as follows: O-3 was exposed at first, then UVC-LED, and this order showed the best reduction ratio ( > 99.9%). Therefore, if O-3 and UVC-LED is used to disinfect Salmonella typhimurium bacteria contained in droplets, bacteria should be separately exposed to O-3 and UVC-LED in order to improve the inactivation efficiency.
ABSTRACT
A detailed molecular fingerprint of raw pyrolysis oil from plastic wastes is a new research area. The present study focuses for the first time on the chemical recycling of plastic marine litter;we aim to chemically characterize the obtained raw pyrolysis oil and its distillates (virgin naphtha and marine gasoil) via GC-MS and FT-IR. For all samples, more than 30% of the detected compounds were identified. 2,4-dimethyl-1-heptene, a marker of PP pyrolysis, is the most represented peak in the chemical signature of all the marine litter pyrolysis samples, and it differentiates commercial and pyrolysis marine gasoil. The presence of naphthalenes is stronger in commercial gasoil, compared to its pyrolysis analog, while the opposite holds for olefins. The overlap between the two molecular fingerprints is impressive, even if saturated hydrocarbons are more common in commercial gasoil, and unsaturated compounds are more common in the gasoil derived from pyrolysis. A technical comparison between the commercial marine gasoil and the one obtained from the marine litter pyrolysis is also attempted. Gasoil derived from marine litter fully complies with the ISO8217 standards for distillate marine fuel. On the other hand, the virgin naphtha is particularly rich in BTX, ethylbenzene, styrene, and alpha olefins, which are all important recoverable platform chemicals for industrial upcycling.
ABSTRACT
In the day we fight against Covid-19, the use of disposable masks and isolation clothing is multiplied by 12 compared to the time before the Covid-19 pandemic. Considering that these disposable masks are made of polypropylene (PP), an average of 480 kilotons of PP waste is produced each year, exclusively from masks. After the use of these masks, it is important to collect and re-evaluate them in a controlled manner so as not to pose a risk of contamination and not to threaten the environment. Because of its advantageous properties, PP is used in the production of many parts in the automotive industry. With this study, it is aimed to develop composite materials to be used in car bumper manufacturing by using recycled PP obtained from melt blown PP fabrics (surgical mask fabric). Due to accidents or road conditions, impact damage can occur on the bumpers. Therefore, the impact resistance of the bumpers must be improved. In addition, in case of microscale damage resulting from the impacts received, microcracks may develop and cause material failure below the maximum tensile stress. In summary, effective reinforcements should be used to improve impact strength in composites for use in car bumpers. Accordingly, novel recycled PP (rPP) based composites are manufactured by using elastomer-styrene-ethylene-butylene-styrene (SEBS) and graphene nanoplatelets (GnPs) as compatible reinforcements with rPP. As experimental characterization, three-point bending tests and Charpy impact tests were carried out. Incorporation of GnPs increased the flexural strength and blending with SEBS improved the impact resistance of the developed composites. Certain clusters of the graphene nanoplatelets were observed by means of microscopy. © 2022, The Society for Experimental Mechanics.
ABSTRACT
PurposeThe surface roughness of additively manufactured parts is usually found to be high. This limits their use in industrial and biomedical applications. Therefore, these parts required post-processing to improve their surface quality. The purpose of this study is to finish three-dimensional (3D) printed acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) parts using abrasive flow machining (AFM).Design/methodology/approachA hydrogel-based abrasive media has been developed to finish 3D printed parts. The developed abrasive media has been characterized for its rheology and thermal stability using sweep tests, thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The ABS and PLA cylindrical parts have been prepared using fused deposition modeling (FDM) and finished using AFM. The experiments were designed using Taguchi (L9 OA) method. The effect of process parameters such as extrusion pressure (EP), layer thickness (LT) and abrasive concentration (AC) was investigated on the amount of material removed (MR) and percentage improvement in surface roughness (%ΔRa).FindingsThe developed abrasive media was found to be effective for finishing FDM printed parts using AFM. The microscope images of unfinished and finished showed a significant improvement in surface topography of additively manufactures parts after AFM. The results reveal that AC is the most significant parameter during the finishing of ABS parts. However, EP and AC are the most significant parameters for MR and %ΔRa, respectively, during the finishing of PLA parts.Practical implicationsThe FDM technology has applications in the biomedical, electronics, aeronautics and defense sectors. PLA has good biodegradable and biocompatible properties, so widely used in biomedical applications. The ventilator splitters fabricated using FDM have a profile similar to the shape used in the present study.Research limitations/implicationsThe present study is focused on finishing FDM printed cylindrical parts using AFM. Future research may be done on the AFM of complex shapes and freeform surfaces printed using different additive manufacturing (AM) techniques.Originality/valueAn abrasive media consists of xanthan gum, locust bean gum and fumed silica has been developed and characterized. An experimental study has been performed by combining printing parameters of FDM and finishing parameters of AFM. A comparative analysis in MR and %ΔRa has been reported between 3D printed ABS and PLA parts.
ABSTRACT
In addition to revealing the cracks in global health care, emergency preparedness, and response systems, COVID-19 also exposed the lack of capacity to run chemical plants safely under such conditions. On 7th May 2020, self-polymerization runaway reaction from an atmospheric storage tank in a polymer facility triggered the release of styrene to the atmosphere, resulting in 12 fatalities and hospitalization of more than 1000 individuals. A similar incident had happened 35 years back at Bhopal involving the release of methyl isocyanate resulting in one of the deadliest process safety incidents to date. Therefore, it is very important to understand the causal factors so that such high-risk incidents can be prevented in future. This paper presents a comprehensive investigative study of styrene gas leak at Vizag with special emphasis on probabilistic risk analysis of the loss of containment. Hazard perception study was performed to understand the possible hazardous scenarios in bulk styrene storage facilities for preventing such catastrophic recurrences. Energy barrier analysis was performed to study the inadequacy of pro-active and reactive barriers with respect to the accident case study. The analysis also considers the escalation factors resulting from extremities of COVID-19 lockdown. The self-polymerization reaction that resulted in toxic styrene dispersion was preventable owing to the advancements in safety engineering and loss prevention since Bhopal Gas Tragedy (1984). Based on the investigative analysis, it can be pointed out that this accident would have occurred even in the absence of COVID-19 restrictions, mainly due to negligence and complacency shown towards safety by the company's management. © 2021 Institution of Chemical Engineers