Prevalence of vitamin D deficiency among patients attending Post COVID-19 follow-up clinic: a cross-sectional study

OBJECTIVE

Post-COVID-19 syndrome appears to be a multi-organ illness with a broad spectrum of manifestations, occurring after even mild acute illness. Limited data currently available has suggested that vitamin D deficiency may play a role in COVID-19 cases. However, to our knowledge, no study has examined the frequency of vitamin D deficiency in post-COVID-19 cases and its effect on the symptom severity. The aim of this study is to both screen the frequency of vitamin D deficiency in post-COVID-19 syndrome patients and to study its relation to persistent symptoms.

PATIENTS AND METHODS

A cross-sectional, single-center study was conducted involving all cases attending post-COVID-19 follow-up clinic from November 2020 to May 2021. Complete history, clinical examination, and laboratory analysis [kidney functions, serum calcium, C-reactive protein, serum ferritin, Serum 25-(OH) vitamin D] was done as well as HRCT chest.

RESULTS

The study included 219 post-COVID-19 cases, 84% had deficient vitamin D levels (< 20 ng/dL); 11.4% had insufficient level (20-30 ng/dL) and only 4.9 % reported normal level. There was no link between levels of vitamin D with either the acute or post-COVID-19 symptoms in the studied groups.

CONCLUSIONS

Despite the prevalence of vitamin D deficiency among the study population, no association was observed between the levels of vitamin D and post-COVID-19 symptoms. It appears that post-COVID-19 syndrome pathophysiology involves a more complex interaction with the immune system. Dedicated clinical trials are advised to better study vitamin D levels and the related disease severity in COVID-19 patients.

Ethylenediaminetetraacetate functionalized MgFe layered double hydroxide/biochar composites for highly efficient adsorptive removal of lead ions from aqueous solutions

The application of layered double hydroxides (LDHs) of MgFe and its composites with biochar of Eucalyptus camdulensis (Eb) and ethylenediaminetetraacetic acid (EDTA) was explored in a batch study to mitigate toxic lead ions (Pb²⁺) from synthetic wastewater solutions. SEM images revealed that MgFe/LDH composites with Eb were successfully formed, while FTIR spectra confirmed the successful adsorption of Pb²⁺ onto the MgFe/LDH and composite adsorbents. Batch equilibrium was attained after 60 min, then the adsorption capacity gradually increased. An increase in adsorption capacity (and a 60% decrease in the percentage removal) was observed by increasing the initial Pb²⁺ concentration, and the highest value was 136 mg g^-1 for MgFe/LDH-Eb_EDTA. A 50–60% increase in both the adsorption capacities and percent removal was seen in the pH range of 2–6. The second-order kinetic model had a nearly perfect fitting, suggesting that chemisorption was the mechanism controlling adsorption. The Langmuir isotherm model best presented the adsorption data, suggesting that the Pb²⁺ adsorption was monolayer, and predicted a better affinity between the adsorbent surface and absorbed Pb²⁺ for MgFe/LDH-Eb_EDTA in comparison to the other two adsorbents. The D–R isotherm suggested that the adsorption system was physical based on E values for all three adsorbents, while the Temkin isotherm model suggested that Pb²⁺ adsorption was heterogeneous. Finally, the Sips and R–P isotherms predicted that the adsorption of Pb²⁺ on the surface of the adsorbents was homogeneous and heterogeneous.

Non-hospitalised COVID-19 patients have more frequent long COVID-19 symptoms

BACKGROUND: Long COVID-19 syndrome refers to the persistence of symptoms for more than 12 weeks after the start of acute symptoms. The pathophysiology of this syndrome is not yet clear.OBJECTIVE: To assess long COVID-19 symptoms in hospitalised and non-hospitalised patients.METHODS: A cross-sectional survey was used. The study included 262 patients who were divided into two groups based on their hospital admission history: 167 (63.7%) were not hospitalised, while 95 (36.3%) were hospitalised.RESULTS: Long-COVID was reported in 157 out of 262 patients (59.9%), and was significantly more frequent in non-hospitalised patients (68.3% vs. 45.3%; P < 0.001). During the acute phase, hospitalised patients had more respiratory symptoms (95.9% vs. 85.6%), while non-hospitalised patients had more neuropsychiatric symptoms (84.4% vs. 69.5%; P < 0.05). Constitutional and neuropsychiatric symptoms were the most frequently reported persistent symptoms in both groups, but all persistent symptoms were more frequent in the non-hospitalised group (P < 0.005).CONCLUSION: Long COVID-19 symptoms affect both hospitalised and non-hospitalised patients. Neuropsychiatric manifestations were the most common persistent COVID-19 symptoms. Rehabilitation and psychotherapy could be advised for all recovered COVID-19 patients. Non-hospitalised COVID-19 patients should be counselled to contact healthcare providers whenever needed.

Comparative study for adsorption of methylene blue dye on biochar derived from orange peel and banana biomass in aqueous solutions

Biochar pyrolyzed at 800 °C from banana (B_b) and orange peels (OP_b) was applied for sorption of methylene blue (MB) dye in a batch system. OP_b showed better affinity for MB dye than B_b with rapid increase in sorption capacity and percent removal for both biochars attaining equilibrium at 30 min. Chemisorption was suggested as the rate limiting step based on the best fitting of the pseudo-second-order reaction kinetics to the batch adsorption data. Linear increase in sorption capacity was seen as the initial MB dye concentration increased from 50 to 300 mg g^-1 with a 40 % decrease in removal efficiency. An increase of 90 mg g^-1 in sorption capacity for both biochars with a 15 and 30 % increase in removal efficiency for OP_b and B_b, respectively, was observed after increasing the solution pH from 2 to 6 or 8. An increase in sorption capacity of about 150 mg g^-1 was seen by increasing the biochar dose from 0.1 to 0.5 g. Langmuir isotherm model represented the adsorption data well as reflected by the high values of R² (0.99) when using both biochar, while least representation of adsorption data was seen in H-J isotherm as estimated from very low R² (0.6-0.66) for both types of biochar. An endothermic nature of MB dye sorption was suggested based on the linear increase in sorption capacity with an increase in solution temperature from 30 to 60 °C. This was further confirmed by the observed positive changes in standard entropy and standard enthalpy while negative values of Gibbs-free energies proposed the non-spontaneous natures of MB dye sorption on to both biochars. The effective sorption of MB dye demonstrated the potential of plant-based biochar as economically viable adsorbents for MB dye.

Nonspontaneous and multilayer adsorption of malachite green dye by Acacia nilotica waste with dominance of physisorption

Adsorption of the hazardous dye malachite green (MG) by Acacia nilotica (AN) waste was investigated. Batch process variables for the adsorption of MG by AN were optimized. The mechanisms involved in the adsorption of MG by AN were explored using isotherms and kinetic models. The thermodynamic parameters were calculated to determine the spontaneity and thermal nature of the MG adsorption reaction. The maximum equilibrium adsorption capacity of AN was found to be 113.26 mg/g at 30 °C. The MG adsorption data revealed that AN adsorbs MG by multilayer adsorption, as shown by the better fit of the data to the Freundlich and Halsey models (R² = 0.99) rather than to the Langmuir model. Multilayer adsorption involves physisorption, which was confirmed by the E value (mean free energy of adsorption) of the Dubinin-Radushkevich model (6.52 kJ/mol). Surface diffusion was found to be the main driving force for MG adsorption by AN. The MG adsorption reaction was endothermic, based on the enthalpy, and was controlled by the entropy of the system in the T₁ temperature range (30 to 40 °C), while the opposite trend was observed in the T₂ range (40 to 50 °C). Moreover, MG adsorption by AN was found to be nonspontaneous at all temperatures.

A best-fit probability distribution for the estimation of rainfall in northern regions of Pakistan

This study was designed to find the best-fit probability distribution of annual maximum rainfall based on a twenty-four-hour sample in the northern regions of Pakistan using four probability distributions: normal, log-normal, log-Pearson type-III and Gumbel max. Based on the scores of goodness of fit tests, the normal distribution was found to be the best-fit probability distribution at the Mardan rainfall gauging station. The log-Pearson type-III distribution was found to be the best-fit probability distribution at the rest of the rainfall gauging stations. The maximum values of expected rainfall were calculated using the best-fit probability distributions and can be used by design engineers in future research.

Enhancing co-metabolic degradation of trichloroethylene with toluene using Burkholderia vietnamiensis G4 encapsulated in polyethylene glycol polymer

The biodegradation potential of Burkholderia vietnamiensis G4 (B. vietnamiensis G4) was evaluated under encapsulation in comparison with direct exposure to trichloroethylene (TCE) (0.1, 0.5, 1 and 5 mg/L) and toluene (10 and 50 mg/L), maintaining aerobic conditions. B. vietnamiensis G4 was encapsulated in polyethylene glycol (PEG) polymer. Under suspended conditions, the degradation rate decreased as the initial TCE concentration increased, even with a higher amount of substrate available. However, the encapsulated systems were less suppressed, presumably by mitigated toxicity, and completely removed TCE with 50 mg/L of toluene. The transformation yield (Ty) was as high as 0.427 mg-TCE/mg-toluene for the encapsulated cultures and 0.1007 mg-TCE/mg-toluene for the suspended cultures. The Ty value for the encapsulated cultures was one to two orders higher than what has been reported in the literature. The higher Ty values in the encapsulated cultures compared with those from suspended cultures showed that the PEG encapsulation provided more a favourable environment for efficient substrate use.

Effects of catchment, first-flush, storage conditions, and time on microbial quality in rainwater harvesting systems

Rainwater collected from a rooftop rainwater harvesting (RWH) system is typically not considered suitable for potable uses, primarily because of poor microbial quality. The quality of stored rainwater, however, can be improved through basic design and maintenance practices during the construction and operation of an RWH system. This paper presents the microbial analysis of rainwater in two RWH systems installed at the Seoul National University Campus in South Korea. Rainwater samples were collected at different locations within each system and analyzed for total and fecal coliforms, Escherichia coli, and heterotrophic plate count bacteria. Within their storage tanks, water quality improved horizontally from inlet to outlet points, and higher quality was observed at the supply point (located about 0.5 m from the base of the tank) than at the surface or bottom of the tank. First-flush rainwater was found to be highly contaminated but rainwater quality improved following about 1 mm of precipitation. The catchment surface also had a significant effect on the quality of rainwater; samples collected from a rooftop exhibited better microbial quality than from a terrace catchment. Better water quality in underground tanks (dark storage conditions) compared to open weirs/ filters (exposed to natural light) demonstrated the importance of storage conditions. Water quality also improved with longer storage, and a decrease of 70% to 90% in microbial concentrations was observed after about 1 week of storage time. The findings of this study demonstrate that the microbial quality of harvested rainwater can be improved significantly by the adoption of proper design and maintenance guidelines such as those discussed in this paper.

Silver disinfection of Pseudomonas aeruginosa and E. coli in rooftop harvested rainwater for potable purposes

Rainwater harvesting being an alternate source in water scarce areas is becoming a common practice. Catchment contact, however, deteriorates the quality of rainwater making it unfit for potable purposes. To improve the quality of harvested rainwater, silver was used as antimicrobial agent in this study. Rainwater samples were taken from underground storage tank of a rooftop rainwater harvesting system installed in one of the buildings at Seoul National University, Seoul, South Korea. The target microorganisms (MOs) were Pseudomonas aeruginosa and Escherichia coli which were measured by using plate count method and standard MPN method, respectively. The efficiency of silver disinfection was evaluated at concentrations, ranging from 0.01 to 0.1 mg/l; the safe limit approved by WHO. The experiments were performed for 168 h with different time intervals to evaluate the parameters including inactivation rate, residual effect of silver and re-growth in both MOs at lower (i.e. 0.01-0.04 mg/l) as well as the higher concentrations of silver (i.e. 0.08-0.1 mg/l). Results showed the re-growth in both MOs was only in the case of lower concentrations of silver. The possible reason of re-growth at these concentrations of silver may be the halting of bacterial cell replication process for some time without permanent damage. The kinetics of this study suggest that higher inactivation and long term residual effect towards both MOs can be achieved with the application of silver at 0.08 mg/l or higher under safe limit.

Roof-harvested rainwater for potable purposes: application of solar collector disinfection (SOCO-DIS)

The efficiency of solar disinfection (SODIS), recommended by the World Health Organization, has been determined for rainwater disinfection, and potential benefits and limitations discussed. The limitations of SODIS have now been overcome by the use of solar collector disinfection (SOCO-DIS), for potential use of rainwater as a small-scale potable water supply, especially in developing countries. Rainwater samples collected from the underground storage tanks of a rooftop rainwater harvesting (RWH) system were exposed to different conditions of sunlight radiation in 2-L polyethylene terephthalate bottles in a solar collector with rectangular base and reflective open wings. Total and fecal coliforms were used, together with Escherichia coli and heterotrophic plate counts, as basic microbial and indicator organisms of water quality for disinfection efficiency evaluation. In the SOCO-DIS system, disinfection improved by 20-30% compared with the SODIS system, and rainwater was fully disinfected even under moderate weather conditions, due to the effects of concentrated sunlight radiation and the synergistic effects of thermal and optical inactivation. The SOCO-DIS system was optimized based on the collector configuration and the reflective base: an inclined position led to an increased disinfection efficiency of 10-15%. Microbial inactivation increased by 10-20% simply by reducing the initial pH value of the rainwater to 5. High turbidities also affected the SOCO-DIS system; the disinfection efficiency decreased by 10-15%, which indicated that rainwater needed to be filtered before treatment. The problem of microbial regrowth was significantly reduced in the SOCO-DIS system compared with the SODIS system because of residual sunlight effects. Only total coliform regrowth was detected at higher turbidities. The SOCO-DIS system was ineffective only under poor weather conditions, when longer exposure times or other practical means of reducing the pH were required for the treatment of stored rainwater for potable purposes.