Toxic trespassers: Uncovering phthalates and organophosphate flame retardants in children's rooms and their health implications.

Organophosphate flame retardants (OPEs) and phthalates have garnered significant attention due to their widespread presence in indoor environments. Many recent investigations have reported extensive contamination of indoor dust, air, children's toys, and other environmental compartments with these chemicals. This research aimed to analyze OPEs and phthalates in air (PM10) and dust samples collected from the bedrooms of children (N = 30) residing in various households in Jeddah, Saudi Arabia. High mean levels (ng/g) of phthalates namely DEHP (1438600) and DnBP (159200) were found in indoor dust while TPhP (5620) was the major OPEs in indoor dust. Similarly, DEHP and DnBP were the predominant phthalates in PM10 samples, exhibiting mean levels of 560 and 680 ng/m3, respectively. However, TCPP was the main OPEs with average levels of 72 ng/m3 in PM10 samples. The majority of individual phthalates and OPEs were detected in 90-100 % of the dust samples, whereas in PM10 samples, their presence ranged from 25 % to 100 %. The concentrations of OPEs were notably greater than those of PBDEs and other BFRs previously reported in these samples, suggesting their broader use than alternative BFRs. The estimated long-term non-carcinogenic risk, hazardous index (HI) and daily exposure via dust for children was above threshold levels for DEHP. On the other hand, the cumulative risk of cancer was below the concerning levels. Further research is required to explore diverse groups of chemicals in indoor microenvironments particularly significant for children, such as kindergartens, primary schools, and their rooms at home.

Nanocellulose-Based Passivated-Carbon Quantum Dots (P-CQDs) for Antimicrobial Applications: A Practical Review.

Passivated-carbon quantum dots (P-CQDs) have been attracting great interest as an antimicrobial therapy tool due to their bright fluorescence, lack of toxicity, eco-friendly nature, simple synthetic schemes, and possession of photocatalytic functions comparable to those present in traditional nanometric semiconductors. Besides synthetic precursors, CQDs can be synthesized from a plethora of natural resources including microcrystalline cellulose (MCC) and nanocrystalline cellulose (NCC). Converting MCC into NCC is performed chemically via the top-down route, while synthesizing CODs from NCC can be performed via the bottom-up route. Due to the good surface charge status with the NCC precursor, we focused in this review on synthesizing CQDs from nanocelluloses (MCC and NCC) since they could become a potential source for fabricating carbon quantum dots that are affected by pyrolysis temperature. There are several P-CQDs synthesized with a wide spectrum of featured properties, namely functionalized carbon quantum dots (F-CQDs) and passivated carbon quantum dots (P-CQDs). There are two different important P-CQDs, namely 2,2'-ethylenedioxy-bis-ethylamine (EDA-CQDs) and 3-ethoxypropylamine (EPA-CQDs), that have achieved desirable results in the antiviral therapy field. Since NoV is the most common dangerous cause of nonbacterial, acute gastroenteritis outbreaks worldwide, this review deals with NoV in detail. The surficial charge status (SCS) of the P-CQDs plays an important role in their interactions with NoVs. The EDA-CQDs were found to be more effective than EPA-CQDs in inhibiting the NoV binding. This difference may be attributed to their SCS as well as the virus surface. EDA-CQDs with surficial terminal amino (-NH2) groups are positively charged at physiological pH (-NH3+), whereas EPA-CQDs with surficial terminal methyl groups (-CH3) are not charged. Since the NoV particles are negatively charged, they are attracted to the positively charged EDA-CQDs, resulting in enhancing the P-CQDs concentration around the virus particles. The carbon nanotubes (CNTs) were found to be comparable to the P-CQDs in the non-specific binding with NoV capsid proteins, through complementary charges, π-π stacking, and/or hydrophobic interactions.

A Novel Microwave Hot Pressing Machine for Production of Fixed Oils from Different Biopolymeric Structured Tissues.

A microwave hot pressing machine (MHPM) was used to heat the colander to produce fixed oils from each of castor, sunflower, rapeseed, and moringa seed and compared them to those obtained using an ordinary electric hot pressing machine (EHPM). The physical properties, namely the moisture content of seed (MCs), the seed content of fixed oil (Scfo), the yield of the main fixed oil (Ymfo), the yield of recovered fixed oil (Yrfo), extraction loss (EL), six Efficiency of fixed oil extraction (Efoe), specific gravity (SGfo), refractive index (RI) as well as chemical properties, namely iodine number (IN), saponification value (SV), acid value (AV), and the yield of fatty acid (Yfa) of the four oils extracted by the MHPM and EHPM were determined. Chemical constituents of the resultant oil were identified using GC/MS after saponification and methylation processes. The Ymfo and SV obtained using the MHPM were higher than those for the EHPM for all four fixed oils studied. On the other hand, each of the SGfo, RI, IN, AV, and pH of the fixed oils did not alter statistically due to changing the heating tool from electric band heaters into a microwave beam. The qualities of the four fixed oils extracted by the MHPM were very encouraging as a pivot of the industrial fixed oil projects compared to the EHPM. The prominent fatty acid of the castor fixed oil was found to be ricinoleic acid, making up 76.41% and 71.99% contents of oils extracted using the MHPM and EHPM, respectively. In addition, the oleic acid was the prominent fatty acid in each of the fixed oils of sunflower, rapeseed, and moringa species, and its yield by using the MHPM was higher than that for the EHPM. The role of microwave irradiation in facilitating fixed oil extrusion from the biopolymeric structured organelles (lipid bodies) was protruded. Since it was confirmed by the present study that using microwave irradiation is simple, facile, more eco-friendly, cost-effective, retains parent quality of oils, and allows for the warming of bigger machines and spaces, we think it will make an industrial revolution in oil extraction field.

Nanobiochar Associated Ammonia Emission Mitigation and Toxicity to Soil Microbial Biomass and Corn Nutrient Uptake from Farmyard Manure.

The unique properties of NB, such as its nano-size effect and greater adsorption capacity, have the potential to mitigate ammonia (NH3) emission, but may also pose threats to soil life and their associated processes, which are not well understood. We studied the influence of different NB concentrations on NH3 emission, soil microbial biomass, nutrient mineralization, and corn nutrient uptake from farmyard manure (FM). Three different NB concentrations i.e., 12.5 (NB1), 25 (NB2), and 50% (NB3), alone and in a fertilizer mixture with FM, were applied to corn. NB1 alone increased microbial biomass in soil more than control, but other high NB concentrations did not influence these parameters. In fertilizer mixtures, NB2 and NB3 decreased NH3 emission by 25% and 38%, respectively, compared with FM alone. Additionally, NB3 significantly decreased microbial biomass carbon, N, and soil potassium by 34%, 36%, and 14%, respectively, compared with FM. This toxicity to soil parameters resulted in a 21% decrease in corn K uptake from FM. Hence, a high NB concentration causes toxicity to soil microbes, nutrient mineralization, and crop nutrient uptake from the FM. Therefore, this concentration-dependent toxicity of NB to soil microbes and their associated processes should be considered before endorsing NB use in agroecosystems.

Environmental evaluation of polyhydroxyalkanoates from animal slaughtering waste using Material Input Per Service Unit.

The massive production and extensive use of fossil-based non-biodegradable plastics are leading to their environmental accumulation and ultimately cause health threats to animals, humans, and the biosphere in general. The problem can be overcome by developing eco-friendly ways for producing plastics-like biopolymers from waste residues such as of agricultural origin. This will solve two currently prevailing social issues: waste management and the efficient production of a biopolymer that is environmentally benign, polyhydroxyalkanoates (PHA). The current study assesses the environmental impact of biopolymer (PHA) manufacturing, starting from slaughterhouse waste as raw material. The Material Input Per Service Unit methodology (MIPS) is used to examine the sustainability of the PHA production process. In addition, the impact of shifting from business-as-usual energy provision (i.e., electricity from distribution grid network and heat provision from natural gas) to alternative renewable energy sources is also evaluated. As a major outcome, it is shown that the abiotic material contribution for PHA production process is almost double for using hard coal as an energy source than the petro-plastic low-density-poly(ethene) (LPDE), which PHA shall ultimately replace. Likewise, abiotic material contribution is 43 % and 7 % higher when using the electricity from the European electricity mix (EU-27 mix) and biogas, respectively, than in the case of LDPE production. However, PHA production based on wind power for energy provision has 12 % lower abiotic material input than LDPE. Furthermore, the water input decreases when moving from the EU-27 mix to wind power. The reduction in water consumption for various electricity provision resources amounts to 20 % for the EU-27 mix, 25 % for hard coal, 71 % for wind, and 70 % for biogas. As the main conclusion, it is demonstrated that using wind farm electricity to generate PHA is the most environmentally friendly choice. Biogas is the second-best choice, although it requires additional abiotic material input.

Phthalate esters and plastic debris abundance in the Red Sea and Sharm Obhur and their ecological risk level.

The abundance of plastic debris (PDs) and its correlation with phthalic acid esters (PAEs), a class of pollutants associated with plastics, is not well understood, although PDs have been reported in relation to the release and distribution of aquatic pollutants such as PAEs. Few studies have linked the distribution of these pollutants in seawater. The current study examined the abundance and relationship of PDs and PAEs in seawater from Sharm Obhur and the Red Sea. Estimates were also made of their ecological impacts. Sharm Obhur is a semi-enclosed bay on the eastern shore of the Red Sea, near Jeddah, Saudi Arabia, and is heavily impacted by human activities. Contaminants from Sharm Obhur may be transported into the deep waters of the Red Sea by the subsurface outflow. The PAEs concentrations in the study area ranged from 0.8 to 1224 ng/L. Among the six PAEs studied, diethyl phthalate (DEP) (22-1124 ng/L), di-n-butyl phthalate (DBP) (9-346 ng/L) and di (2-ethylhexyl) phthalate (DEHP) (62-640 ng/L) were the predominant additives detected across all the sampling sits. Whereas the other PAEs, dimethyl phthalate (DMP) (5-76 ng/L), benzyl butyl phthalate (BBP) (4-25 ng/L) and di-n-octyl phthalate DnOp (0.5-80 ng/L) were generally lower in most samples. The sum of the six analyzed PAEs (∑6 PAEs) was lower at Sharm Obhur (587 ± 82 ng/L) and in the Red Sea shelf (677 ± 182 ng/L) compared to the Red Sea shelf break (1266 ± 354 ng/L). This suggests that degradation and adsorption of PAEs were higher in Sharm Obhur and on the shelf than on the shelf break. In contrast, there was no difference in the abundance of PDs between Sharm Obhur (0.04 ± 0.02 PDs/m3), Red Sea shelf (0.05 ± 0.02 PDs/m3) and in the Red Sea shelf break (0.03 ± 0.1 PDs/m3). Polyethylene (32%) and polypropylene (8%) were dominant, mostly smaller than 5 mm2 (78%), with the majority consisting of white (52%) and black (24%) fragments (39%), fibers (35%) and films (24%). A positive correlation between PAE concentration and abundance of PDs, suggests either a common source or a causal link through leaching. The ecological risk of ∑4PAEs (DMP, DEP, DBP and DEHP) ranged from (0.20-0.78), indicating a low to moderate risk for the Red Sea. The pollution index of PDs ranged from (0.14-0.36), showing that the Sharm Obhur and both sites of Red Sea suffered relatively low pollution.

The effects of salinity, temperature, and UV irradiation on leaching and adsorption of phthalate esters from polyethylene in seawater.

In this study, the leaching of six phthalic acid esters (PAEs) from three common consumer plastics was investigated: low and high density polyethylene (LDPE, HDPE) and recycled polyethylene (RP). The effects of salinity, temperature, and ultraviolet irradiation (UVR) on leaching were investigated. The study of leaching of phthalates in aqueous environments in batch experiments is challenging due to their readsorption by the high hydrophobicity of PAEs, and there are no standard methods to study release processes. Here with the experiments, leaching (A) and spiking (B) using six PAEs to study the readsorption in the leaching process. PAEs were identified and quantified using GC-MS. Dibutyl phthalate (DBP) and benzyl butyl phthalate (DEHP) showed considerable leaching during the 5-day incubation: 14 ±â€¯1 to 128 ±â€¯14 and 25 ±â€¯2 to 79 ±â€¯5 ng/cm2, respectively, under UVR, corresponding approximately to (1.9-13%) and (12.4-22.4%) of the solvent extracted mass. The highest Kd values were measured for RP polymers (0.3-9.4), followed by LDPE (0.5-5.4) and HDPE (0.2-2.2) polymers. Thus, readsorption of PAEs at the surface removed 30-80% of the leached PAEs in the dissolved phase. For example in LDPE, the calculated total release of DBP was up to 54 ±â€¯4 ng/cm2, while the dissolved amount was 8.5 ±â€¯1 ng/cm2 during the 5-day incubation under freshwater conditions. Increasing salinity negatively affected the leaching rate, which decreased for DBP from 54 ±â€¯4 ng/cm2 in freshwater to 44 ±â€¯3 and 38 ±â€¯3 ng/cm2 at salinity of 20 and 40 g/L, respectively, from LDPE during the 5-day incubation. Temperature and UVR had a positive effect on the leaching rate, with the release of DBP from LDPE increasing from 44 ±â€¯3 ng/cm2 at room temperature (25 °C) to 60 ±â€¯6 and 128 ±â€¯14 ng/cm2 at high temperature (40 °C) and UVR, respectively. Overall, this study highlights the positive relationship between temperatures, UVR on the extent of leaching and surface adsorption on the leaching measurements.

The role of size-controlled CeO2 nanoparticles in enhancing the stability and photocatalytic performance of ZnO in natural sunlight exposure.

In order to enhance the photocatalytic performance and stability, the various proportions of the size controlled cerium oxide (CeO2) nanoparticles were dispersed at the pre-synthesized ZnO. Although, the expected dual absorption onsets, probably due to the diminutive difference between the bandgaps of CeO2 (∼2.9 eV) and ZnO (∼3.1 eV), were not observed however, a blue shift in the bandgap energy of ZnO was witnessed with the increasing surface density of CeO2 particles. The delayed excitons recombination process with the increasing concentration of CeO2 nanoparticles was verified by the PL spectra. The structural investigation by Raman and XRD analysis revealed the surface attachment of CeO2 particles without altering the rock-salt lattice of ZnO. The morphological and fine microstructural analysis established the uniform distribution of evenly sized CeO2 particles at the surface of ZnO with the discrete fringe patterns of both the entities whereas the XPS analysis confirmed the majority of Ce4+ in dispersed CeO2. In comparison to pure ZnO, cyclic voltammetric (CV) analysis, under illumination, exposed the supportive role of surface residing CeO2 particles in eradicating the photo-corrosion of ZnO whereas the chronopotentiometry (CP) predicted the prolonged life-span of the excitons. Compared to pure ZnO, an appreciably high activity was revealed for 10% CeO2 loading as compared to pure ZnO for the removal of mono and di-nitrophenol derivatives and their mixtures under natural sunlight exposure. The variations in the removal rates in the mixture as compared to individual nitrophenol exposed the structure-based priority of ROS for the respective phenol. The significantly enhanced photocatalytic activity of the composite catalysts revealed the incremental role of surface-mounted CeO2 entities in boosting the generation of ROS under sunlight irradiation. The experimental observations were correlated and compiled to establish the mechanism of the removal process.

Temperature, humidity and outdoor air quality indicators influence COVID-19 spread rate and mortality in major cities of Saudi Arabia.

There is an increasing evidence that meteorological (temperature, relative humidity, dew) and air quality indicators (PM2.5, PM10, NO2, SO2, CO) are affecting the COVID-19 transmission rate and the number of deaths in many countries around the globe. However, there are contradictory results due to limited observations of these parameters and absence of conclusive evidence on such relationships in cold or hot arid tropical and subtropical desert climate of Gulf region. This is the first study exploring the relationships of the meteorological (temperature, relative humidity, and dew) and air quality indicators (PM10,CO, and SO2) with daily COVID-19 infections and death cases for a period of six months (1st March to August 31, 2020) in six selected cities of the Kingdom of Saudi Arabia by using generalized additive model. The Akaike information criterion (AIC) was used to assess factors affecting the infections rate and deaths through the selection of best model whereas overfitting of multivariate model was avoided by using cross-validation. Spearman correlation indicated that exponentially weighted moving average (EWMA) temperature and relative humidity (R > 0.5, P < 0.0001) are the main variables affecting the daily COVID-19 infections and deaths. EWMA temperature and relative humidity showed non linear relationships with the number of COVID-19 infections and deaths (DF > 1, P < 0.0001). Daily COVID-19 infections showed a positive relationship at temperature between 23 and 34.5 °C and relative humidity ranging from 30 to 60%; a negative relationship was found below and/or above these ranges. Similarly, the number of deaths had a positive relationship at temperature ˃28.7 °C and with relative humidity ˂40%, showing higher number of deaths above this temperature and below this relative humidity rate. All air quality indicators had linear relationships with the number of COVID-19 infections and deaths (P < 0.0001). Hence, variation in temperature, relative humidity and air pollution indicators could be important factors influencing the COVID-19 spread and mortality. Under the current scenario with rising temperature and relative humidity, the number of cases is increasing, hence it justifies an active government policy to lessen COVID-19 infection rate.

Biosynthesis Microwave-Assisted of Zinc Oxide Nanoparticles with Ziziphus jujuba Leaves Extract: Characterization and Photocatalytic Application.

The present work is intended to biosynthesize zinc oxide nanoparticles (ZnO NPs) via facile and modern route using aqueous Ziziphus jujuba leaves extract assisted by microwave and explore their photocatalytic degradation of methyl orange anionic dye and methylene blue cationic dye under solar irradiation. The biosynthesized microwave assisted ZnO NPs were characterized and the results showed that ZnO NPs contain hexagonal wurtzite and characterized with a well-defined spherical-like shape with an outstanding band gap (2.70 eV), average particle size of 25 nm and specific surface area of 11.4 m2/g. The photocatalytic degradation of the MO and MB dyes by biosynthesized ZnO NPs under solar irradiation was studied and the results revealed the selective nature of the ZnO NPs for the adsorption and further photocatalytic degradation of the MO dye compared to the MB dye. In addition, the photocatalytic degradation of MO and MB dyes by the ZnO NPs under solar radiation was fitted by the first-order kinetics. Moreover, the photodegradation mechanism proposed that superoxide ions and hydroxyl radicals are the main reactive species.

Exposure to Phthalate and Organophosphate Esters via Indoor Dust and PM10 Is a Cause of Concern for the Exposed Saudi Population.

In this study, we measured the occurrence of organophosphate esters (OPEs) and phthalates in the settled dust (floor and air conditioner filter dust) and in suspended particulate matter (PM10) from different microenvironments (households (n = 20), offices (n = 10) and hotels (n = 10)) of Jeddah, Saudi Arabia. Bis (2-Ethylhexyl) phthalate (DEHP) was the major pollutant (contributing >85% of total chemicals burden) in all types of indoor dust with a concentration up to 3,901,500 ng g-1. While dibutyl phthalate (DBP) and DEHP together contributed >70% in PM10 (1900 ng m-3), which indicate PM10 as a significant source of exposure for DBP and DEHP in different Saudi indoor settings. Tris (1-chloro-2-propyl) phosphate (TCPP) was the major OPE in PM10 with a concentration of up to 185 ng m-3 and the occurrence of OPEs in indoor dust varied in studied indoor settings. The estimated daily intake (EDI) of studied chemicals via dust ingestion and inhalation of PM10 was below the reference dose (RfD) of individual chemicals. However, estimated incremental lifetime cancer risk (ILCR) with moderate risk (1.5 × 10-5) for Saudi adults and calculated hazardous index (HI) of >1 for Saudi children from DEHP showed a cause of concern to the local public health.

Sustainability Evaluation of Polyhydroxyalkanoate Production from Slaughterhouse Residues Utilising Emergy Accounting.

High raw material prices and rivalry from the food industry have hampered the adoption of renewable resource-based goods. It has necessitated the investigation of cost-cutting strategies such as locating low-cost raw material supplies and adopting cleaner manufacturing processes. Exploiting waste streams as substitute resources for the operations is one low-cost option. The present study evaluates the environmental burden of biopolymer (polyhydroxyalkanoate) production from slaughtering residues. The sustainability of the PHA production process will be assessed utilising the Emergy Accounting methodology. The effect of changing energy resources from business as usual (i.e., electricity mix from the grid and heat provision utilising natural gas) to different renewable energy resources is also evaluated. The emergy intensity for PHA production (seJ/g) shows a minor improvement ranging from 1.5% to 2% by changing only the electricity provision resources. This impact reaches up to 17% when electricity and heat provision resources are replaced with biomass resources. Similarly, the emergy intensity for PHA production using electricity EU27 mix, coal, hydropower, wind power, and biomass is about 5% to 7% lower than the emergy intensity of polyethylene high density (PE-HD). In comparison, its value is up to 21% lower for electricity and heat provision from biomass.

Synthesis, characterization and photocatalytic performance of W6+ impregnated g-C3N4 for the removal of chlorophenol derivatives in natural sunlight exposure.

The surface of the g-C3N4 was altered by impregnating W6+ ions that transformed to homogeneously coated oxide layer by a calcination process. An enhanced absorption and the suppressed de-excitation in the emission spectra, with the increasing W6+ loading, exposed the supporting role of the coated layer in extending the spectral response as well as the prolonged life span of excitons. The same was further supported by electrochemical impedance spectroscopy (EIS). The XRD and XPS analysis revealed the coated layer as highly crystalline pure phase monoclinic WO3 with the majority of impregnated tungsten ions in 6+ oxidation state respectively, whereas the FESEM and HRTEM analysis substantiated the uniformity of the coated layer with the interlayer spacing of the 0.369 nm. Additionally, the probable formation of individual WO3 nanoparticles or clusters was ruled out. The as-synthesized impregnated photocatalysts, in comparison to pure g-C3N4, were subjected to natural sunlight exposure for the photocatalytic removal of chlorophenol derivatives (2-CP, 3-CP, 4-CP, 2,3-DCP, 2,4-DCP, 2,4,6-TCP and PCP) that revealed the 5 wt% coating as the optimum level for significant removal. The progress of the photocatalytic process was monitored by periodic HPLC analysis whereas ion chromatography (IC) was used for the estimation of released ions. The mineralization capability of the as-synthesized W6+ coated catalysts was measured by the time scale TOC measurements. As the formation of intermediates was indicated in HPLC analysis, selected samples were subjected to GC-MS analysis for the identification of the nature of intermediates. The variable degree of removal of chlorophenol derivatives signified the role of the position and orientation of Cl group. The kinetics of the removal process was evaluated with the calculation of rate constants. The results extracted from the analytical tools and the associated band edge potentials were correlated to speculate the probable mechanism as well as the identification of major reactive oxygen species (ROS) involved in the removal process.

Arsenic and lead in the indoor residential settings of different socio-economic status; assessment of human health risk via dust exposure.

In the present study, occurrence of arsenic (As) and lead (Pb) is reported in rural and urban household dust (floor and AC filter dust) of the Kingdom of Saudi Arabia (KSA). Several studies have found concerning concentrations of these toxic metals in indoor dust from different countries, but data from this region is missing. The association between studied toxic metals and different socioeconomic parameters was investigated. Furthermore, health risk associated with these toxic metals via dust exposure was evaluated for the Saudi population. Mean concentration of Pb was several times higher than As in both types of dust samples. AC filter dust was more contaminated with these metals than floor dust. Levels of Pb were up to 775 ppm in AC filter dust from urban areas, while 167 ppm in rural AC filter dust. Different socioeconomic parameters did not influence much on the presence of studied metals in both AC and floor dust. To estimate health risk from contaminated dust hazardous index (HI), hazardous quotient (HQ), and incremental lifetime cancer risk (ILCR) via dust ingestion, inhalation, and dermal contact was calculate using USEPA equations. The ILCR range for both toxic metals was within the tolerable range of reference values of USEPA (1 × 10-5 to 5 × 10-7). Nonetheless, HI was close to 1 for Pb via dust exposure for young urban children, which signifies the risk of non-carcinogenic health problems in studied area. Graphical abstract.

Comparing and Contrasting MERS, SARS-CoV, and SARS-CoV-2: Prevention, Transmission, Management, and Vaccine Development.

The COVID-19 pandemic is responsible for an unprecedented disruption to the healthcare systems and economies of countries around the world. Developing novel therapeutics and a vaccine against SARS-CoV-2 requires an understanding of the similarities and differences between the various human coronaviruses with regards to their phylogenic relationships, transmission, and management. Phylogenetic analysis indicates that humans were first infected with SARS-CoV-2 in late 2019 and the virus rapidly spread from the outbreak epicenter in Wuhan, China to various parts of the world. Multiple variants of SARS-CoV-2 have now been identified in particular regions. It is apparent that MERS, SARS-CoV, and SARS-CoV-2 present with several common symptoms including fever, cough, and dyspnea in mild cases, but can also progress to pneumonia and acute respiratory distress syndrome. Understanding the molecular steps leading to SARS-CoV-2 entry into cells and the viral replication cycle can illuminate crucial targets for testing several potential therapeutics. Genomic and structural details of SARS-CoV-2 and previous attempts to generate vaccines against SARS-CoV and MERS have provided vaccine targets to manage future outbreaks more effectively. The coordinated global response against this emerging infectious disease is unique and has helped address the need for urgent therapeutics and vaccines in a remarkably short time.

Recent Advances in Metal Decorated Nanomaterials and Their Various Biological Applications: A Review.

Nanoparticles (nanoparticles) have received much attention in biological application because of their unique physicochemical properties. The metal- and metal oxide-supported nanomaterials have shown significant therapeutic effect in medical science. The mechanisms related to the interaction of nanoparticles with animal and plant cells can be used to establish its significant role and to improve their activity in health and medical applications. Various attempts have been made to discuss the antibiotic resistance and antimicrobial activity of metal-supported nanoparticles. Despite all these developments, there is still a need to investigate their performance to overcome modern challenges. In this regard, the present review examines the role of various types of metal-supported nanomaterials in different areas such as antibacterial, antifungal, anticancer, and so on. Based on the significant ongoing research and applications, it is expected that metal-supported nanomaterials play an outstanding role not only in medical but also in other important areas.

Spectroscopic Assessment of Platinum Group Elements of PM10 Particles Sampled in Three Different Areas in Jeddah, Saudi Arabia.

Platinum group elements (PGE) including Ru, Rh, Pt and Pd have been quantified in air particulate matter with an aerodynamic diameter equal or less than 10 microns (PM10) using inductively coupled plasma mass spectrometry (ICP-MS). PM10 aerosols have been collected from three sites representing various activities in Jeddah city, Saudi Arabia. These locations are residential site with heavy traffic, industrial site and heavy traffic and a light traffic site outside the city. To obtain reasonable data of the PGE concentrations, a group from 10 to 15 PM10 samples were collected every month. The annual and seasonal variation of the mass concentration of the PGE were demonstrated. In all locations, Pt and Pd were relatively higher than Ru and Rh possibly because their main use is in automobile catalytic converters. Concentrations of observed PGE in PM10 could be arranged in ascending order as: Rh < Ru < Pd < Pt. In case of Ru and Pt, there are clear similarities in terms of the overall mean concentrations at the sampling locations. Due to the high concentration of Ru, Rh and Pd at low traffic site, there are certainly other sources of these elements rather than vehicle catalytic converters. However, at the industrial/heavy traffic location, high concentrations of Ru were detected during February 2015. In addition, high Pt concentrations were also detected at the light traffic site during May 2015. Results indicate that Pt source in PM10 is mainly the automobile catalytic converters.

Trace metals in different socioeconomic indoor residential settings, implications for human health via dust exposure.

In this study a number of heavy metals namely chromium (Cr), cadmium (Cd), zinc (Zn), barium (Ba), copper (Cu), manganese (Mn), cobalt (Co), rubidium (Rb), selenium (Se) are studied in the floor and air condition (AC) filter dust collected from urban and rural households of Saudi Arabia. To the best of our knowledge, many of these heavy metals are reported for the very first time in the indoor dust of Saudi Arabia. Studied metals were higher in urban dust than rural except Mn and Rb which were significantly higher (P < 0.05) in rural dust. All metals, except Cd, Zn, and Ba in urban settings, were detected at higher (P < 0.05) levels in AC filter dust than household floor dust from both rural and urban residential settings. Levels of the two dominant metals i.e., Zn and Mn were up to 1600 and 700 µg/g, respectively in studied dust samples. Also associations between heavy metals and a number of different socio-economic parameters were studied which was significant for some trace metals. In literature exposure to many of trace metals are associated with various health problems, therefore health risk assessment for the Saudi population was calculated by incremental lifetime cancer risk (ILCR) and hazardous index (HI) via dust ingestion, inhalation, and dermal contact. The ILCR for all metals was within the tolerable range of reference values of USEPA (1 × 10- 11 to 1 × 10- 4). However, calculated HI for Mn, Cu, Ni, and Zn was more than 1 via dust exposure, which signifies the non-carcinogenic risk. The study highlights the occurrence of toxic metals in the indoor environments of Saudi Arabia and provides baseline data for future studies on these toxic metals in the region.

Antibacterial Silver Nanomaterial Synthesis From Mesoflavibacter zeaxanthinifaciens and Targeting Biofilm Formation.

Considering the significance of biological and eco-friendly nanomaterials, in the present study, we have synthesized silver nanoparticles from the exopolysaccharide of recently recovered bacterial strain CEES51 from the Red Sea coastal area of Jeddah, Saudi Arabia. 16S ribosomal RNA gene sequencing was used to characterize the isolated bacteria, and it was identified as Mesoflavibacter zeaxanthinifaciens and assigned an accession number MH707257.1 GenBank. The bacterial strain is an excellent exopolysaccharide producer and survived at hypersaline (30%) and high-temperature (50°C) conditions. The bacterial exopolysaccharides were employed for the fabrication of silver nanoparticles at room temperature. UV-visible spectrophotometer optimized the synthesized nanoparticles, and their size was determined by Nanophox particle size analyzer and dynamic light scattering. Additionally, the X-ray powder diffraction and Fourier-transform infrared spectroscopy studies also approved its crystalline nature and the involvement of organic functional groups in their formation. The synthesized nanomaterials were tested for their antibacterial and antibiofilm properties against pathogenic microorganisms Bacillus subtilis and methicillin-resistant Staphylococcus aureus. The antimicrobial property showed time, and dose-dependent response with a maximum of zone inhibition was observed at around 22 and 18 mm at a dose of 50 µg/well against B. subtilis and S. aureus and a minimum inhibitory concentration of 8 and 10 µg/ml, respectively. Furthermore, the synthesized silver nanoparticles possessed a substantial antibiofilm property and were also found to be biocompatible as depicted by red blood cell lysis assay and their interaction with peripheral blood mononuclear cells and human embryonic kidney 293 cells. Therefore, Mesoflavibacter zeaxanthinifaciens is found to be an excellent source for exopolysaccharide synthesis that assists in the silver nanoparticle production.