ABSTRACT
Nitrogenated graphene oxide-decorated copper sulfide nanocomposites (Cu x S-NrGO, where x = 1 and 2) are designed to be incorporated in polysulfone (PSF) membranes for effective fouling resistance of PSF membranes and their dye removal capacity. The developed membranes possess more hydrophilicity and an enhancement in pure water flux (PWF). Also, the highest bovine serum albumin (BSA) rejection of 89% was observed when compared to membranes with pristine PSF (5 L/m2 h PWF and 88% BSA rejection) and CuS-incorporated PSF membranes (14 L/m2 h PWF and 83% BSA rejection) because of N doping and enhanced permeability. It is also found that the Cu x S-NrGO-incorporated PSF membranes exhibited a significantly higher fouling resistance, a larger permeate flux recovery ratio (FRR) of nearly 82%, and a congo red dye rejection of 93%. Cu x S-NrGO nanoparticles thus demonstrate the potential efficacy of enhancing the hydrophilicity, leading to a better flux, dye removal capacity, and antifouling capacity with a very high FRR value of 82% because of a strong interaction between the N-active sites of the NrGO, Cu x S, and polysulfone matrix, and negligible leaching of nanoparticles is observed.
ABSTRACT
Nanostructured polymeric membranes are of great importance in enhancing the antifouling properties during water filtration. Nanomaterials with tunable size, morphology and composition, surface modification, and increased functionality provide considerable opportunities for effective wastewater treatment. Thus, in this work, an attempt has been made to use spinel-structured MnCo2O4 as a nanofiller in the fabrication of nanostructured polysulfone (PSF) mixed matrix membranes and is investigated in terms of morphology, hydrophilicity, permeability, protein and natural organic matter separation, dye removal, and, finally, antifouling properties. The MnCo2O4 nanomaterials are synthesized and characterized via X-ray diffraction and field emission scanning electron microscopy and are loaded into a membrane matrix with varied concentrations (0 to 1.5 wt %). PSF nanocomposite membranes are prepared via a nonsolvent-induced phase-separation process. The results show an enhancement in hydrophilicity, porosity, and permeability with respect to the modified nanocomposite membranes because of oxygen-rich species in the membrane matrix, which increases affinity toward water. It was also found that the modified membranes display remarkably greater pure water flux (PWF) (220 L/m2 h), higher Congo red rejection coefficient (99.86%), higher humic acid removal (99.81%), higher fouling resistance, and a significant flux recovery ratio (FRR) (88%) when tested with bovine serum albumin protein when compared to a bare PSF membrane (30 L/m2 h PWF and 35% FRR). This is because the addition of MnCo2O4 nanoparticles into the polymeric casting solution yielded tighter PSF membranes with a denser skin layer and greater selectivity. Thus, the enhanced permeability, greater rejection coefficient, and antifouling properties show the promising potential of the fabricated PSF-spinel nanostructured membrane to be utilized in membrane technology for wastewater treatment.
ABSTRACT
SARS-CoV2 is transmitted primarily through oral mouth secretions and respiratory droplets. Commercial mouthwashes, povidone iodine (PI), hydrogen peroxide (HP) and chlorhexidine (CHX) have been tested in cell culture and RT-PCR studies for their efficacy to reduce SARS-CoV2 burden. Here, we evaluated SARS-CoV2 burden in whole mouth fluid (WMF) and respiratory droplets (RD) samples before and after the use of PI, HP or CHX mouthwashes in hospitalized COVID-19 patients using RT-PCR and rapid antigen test (RAT). Thirty-six SARS-CoV2 RT-PCR-positive in-patients were randomly assigned to one of the four groups: 20 and 60 minutes after 1% w/v PI or 1.5% HP; 90 and 180 minutes after 1.5% HP or 0.2% w/v CHX. WMF and RD samples were collected concurrently at baseline and after the two different time points. RD (92%) showed a higher reduction in SARS-CoV2 burden than WMF samples (50%; p=0.008). SARS-CoV2 burden was statistically lower at both 20 minutes (p=0.02) and 60 minutes (p=0.03) with PI; at 20 minutes with HP (p=0.0001); and 90 minutes with CHX (p=0.04). The overall and individual mean logarithmic reductions in the WMF and RD samples were greater than 1.0 at 20, 60 and 90 minutes after PI, HP or CHX. RAT-positive patients at 90 minutes post-treatment (n=3) demonstrated a one log increase in virus copies. Among the three RAT-negative post-treatment patients, SARS-CoV2 burden declined by one log in two while the third patient had a slight increase in RNA copies. In conclusion, we have shown for the first time that the mouthwashes, PI, HP and CHX can reduce the SARS-CoV2 burden in the concurrently collected RD and WMF samples. RAT is more appropriate than RT-PCR to evaluate the efficacy of the mouthwashes.
ABSTRACT
ImportanceThe nasopharyngeal swab (NPS) is considered the ideal diagnostic specimen for Covid-19, while WMF is recently promoted due to collection simplicity and importance in disease transmission. There is limited knowledge on the relative viral load in these samples - NPS, whole mouth fluid (WMF) and respiratory droplets (RD; another important source in transmission), on how the loads vary with disease severity and on how much virus is shed. ObjectiveTo quantify and compare SARS-CoV2 copies in the NPS, WMF and RD samples, and correlate with disease severity. DesignCross sectional study. SettingTertiary care multi-speciality hospital with limited resources in a low-to-middle income country. ParticipantsEighty suspected COVID-19 patients were recruited from the COVID-19 out-patient clinic and hospital isolation wards. InterventionConcurrent NPS, WMF and RD samples were collected from all the recruited patients and tested for SARS-CoV2 copies by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). Main outcomes and measuresThe main outcome was COVID-19 measured by SARS-CoV2 quantitative RT-PCR in NPS samples. COVID-19 disease severity was determined according to NIH criteria. Virus shedding was defined as the presence of SARS-CoV2 copies in the WMF and RD samples. ResultsSARS-CoV2 was detected in 55/80 (69%) of the NPS samples. Of these 55, WMF and RD samples were positive in 44 (80%) and 17 (31%), respectively. The concordance of WMF with NPS was 84% (p=0.02). SARS-CoV2 copy numbers were comparable in the NPS (median: 8.74x10^5) and WMF (median: 3.07x10^4), but lower in RD samples (median: 3.60x10^2). Patients with mild disease had higher copies in the NPS (median: 3.46x10^6), while patients with severe disease had higher copies in the WMF (median: 1.34x10^6) and RD samples (median: 4.29x10^4). The 25-75% interquartile range of NPS SARS-CoV2 copies was significantly higher in the WMF (p=0.0001) and RD (p=0.01) positive patients. Conclusion and relevanceSARS-CoV2 copies are highest in NPS samples. WMF is a reliable surrogate sample for diagnosis. High copy numbers in the NPS imply initial virological phase and higher risk of virus shedding via WMF and RD. Key pointsO_ST_ABSQuestionC_ST_ABSHow the numbers of SARS-CoV2 copies in nasopharyngeal swab (NPS) samples might reflectvirus shedding from the whole upper aerodigestive tract and indicatedisease severity? FindingsIn this cross-sectional study involving 80 suspected COVID-19 patients, the data indicate higher SARS-CoV2 copies in NPS samples of patients with mild disease,and in the whole mouth fluid (WMF) and respiratory droplet (RD) samples of patients with severe disease. Patients with higher SARS-CoV2 copies in the NPS shed the virus in the WMF and RD samples at statistically higher levels. MeaningHigh SARS-CoV2 copies in NPS samples imply initial virological phase withhigh levels of shedding through both WMF and RD.
ABSTRACT
IntroductionSARS-CoV2, the aetiological agent of the current COVID-19 pandemic, has been detected in saliva and recently implicated in several oral diseases. Collection of nasopharyngeal swabs (NPS) and detection by reverse transcriptase-polymerase chain reaction (RT-PCR) requires medical / technical expertise. A reliable and easy to handle point-of-care (POC) test is highly desirable, especially to curb transmission. Therefore, in this study, we evaluated a commercially available POC rapid antigen test (RAT) for the detection of SARS-CoV2 antigens in the saliva of RT-PCR confirmed positive and negative patients. MethodsThirty saliva samples of 10 saliva RT-PCR negative and 20 saliva RT-PCR positive patients were tested by RAT. ResultsRAT was negative in 10/10 (100%) RT-PCR-negative samples; positive in 9/20 (45%) RT-PCR-positive samples; concordance was 63% (p=0.001). Patients with positive RAT had higher virus copies in their NPS samples compared to the RAT-negative patients. This difference was also statistically significant (p=0.01). ConclusionThus, the POC RAT may be used to detect SARS-CoV2 as a reliable tool for self-testing, large-scale population screening and emergency medical/dental screening. Patients negative by RAT should be confirmed by RT-PCR.
