Recent progresses in bentonite/lignin or polysaccharide composites for sustainable water treatment.

Today, with the growth of the human population, industrial activities have also increased. Different industries such as painting, cosmetics, leather, etc. have broadly developed, and as a result, they also produce a lot of pollutants. These pollutants can enter the environment and pollute water, air, and soil. Organic dyes, nitro compounds, drug residues, pesticides and herbicides are pollutants that should be removed from the environment. Natural polymers or biopolymers are important types of organic materials that are broadly applied for different applications. Among them, polysaccharides and lignin, which are two types of biopolymers, have attracted much consideration owing to their advantages such as biocompatibility, environmental friendly, safety, availability, etc. Polysaccharides include cellulose, gum, starch, alginate (Alg), chitin, and chitosan (CS). On the other hand, bentonite is one of the types of clays, which owing to their properties like large specific surface area, adsorption performance, naturally available, etc., have drawn the interest of many researchers. As a result, the synthesis of a composite including polysaccharide/lignin and bentonite can be very efficient for different applications, especially environmental ones. In this review, we instigated the preparation of these composites as well as the removal performance of them. In fact, we reported recent advancements in the synthesis of lignin- and polysaccharide-bentonite composites for the removal of diverse kinds of contaminants like organic dyes, nitro compounds, and hazardous materials.

Design and manufacture of 3D-cylindrical scaffolds based on PLA/TPU/n-HA with the help of dual salt leaching technique suggested for use in cancellous bone tissue engineering.

A series of 3-D scaffolds based on polylactic acid (PLA) and thermoplastic polyurethane (TPU) as major phase and hydroxyapatite nanoparticles (n-HA) were prepared by using the dual leaching technique. Fourier-transform infrared spectroscopy analysis showed that almost the interactions between the constituent materials can be identified based on their functional groups. The results of thermogravimetric analysis were used to obtain the best time to prepare the samples without residual of any progen additives. The scanning electron macroscopy images clearly proved that the dual leaching technique is an effective method to prepare the appropriate morphology and also a very good dispersion and distribution for n-HA can be obtained. Dynamic contact angles showed that the presence of TPU in the PLA matrix has a positive effect on the hydrophilicity of the scaffolds. The bulk modulus (κ) values of S-PLA70TPU30H5 in dry and wet conditions were 321 and 212 Pa, respectively and the compressibility coefficient (ß) of pure samples was higher than that of other scaffolds, while among the nanocomposite samples, the compressibility coefficient of S-PLA70TPU30H5 and S-PLA50TPU50H5 samples in dry and wet conditions was higher than that of other samples. Biological tests such as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) tetrazolium reduction assay, cell adhesion, 4',6-diamidino-2-phenylindole (DAPI) analysis and alizarin red were also performed, and the results obtained for 3D scaffolds were good. In the DAPI analysis test, sample 3D-S-PLA70TPU30H5 showed good behavior, and also in the alizarin red test, the amount of minerals created in 3D-S-PLA50TPU50H5 was significant.

Dual leaching technique was used to prepare cylindrical scaffolds with high porosity.3D cylindrical scaffolds based on PLA/TPU/n-HA were proposed for use in cancellous bone.Bulk modulus and compressibility coefficient of 3D cylindrical scaffolds were obtained in wet and dry conditions.DAPI analysis showed the role of n-HA nanoparticles on cell growth in 3D cylindrical scaffolds.Alizarin red studies showed that sample PLA50TPU50H5 has more calcium content.

Enhanced survival of Lacticaseibacillus rhamnosus in simulated gastrointestinal conditions using layer-by-layer encapsulation.

OBJECTIVE: The release behavior of Lacticaseibacillus rhamnosus from single bilayer microcapsules of alginate-chitosan (AC) and its double bilayer (ACAC) was investigated in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF). Methods Multilayer polyelectrolyte AC microcapsules were fabricated using the layer-by-layer (LbL) self-assembly technique through electrostatic interactions. Results AC and ACAC microcapsules kept their integrity and mechanical stability in simulated gastric conditions. Bacterial cells remained inside microcapsules in SGF and dissolution of microcapsules was observed in SIF. To improve the bacterial survivability, L. rhamnosus was co-encapsulated in a double bilayer of AC hydrogels with calcium carbonate as an antacid agent. Conclusions The LbL self-assembly technology provides stable and target release for ACAC microcapsules. Therefore, the double bilayer polyelectrolyte microcapsules have a remarkable potential for successful application in the targeted and controlled delivery of different probiotics and drugs.

Human Responses in Public Health Emergencies for Infectious Disease Control: An Overview of Controlled Topologies for Biomedical Applications.

COVID-19 originated in Wuhan city of Hubei Province in China in December three years ago. Since then, it has spread to more than 210 countries and territories. This disease is caused by Severe Acute Respiratory Syndrome Coronavirus 2. The virus has a size of one to two nanometers and a single-stranded positive RNA. Droplets spread the virus from coughing and sneezing. This condition causes coughing, fever, acute respiratory problems, and even death. According to the WHO, the virus can survive outside the body for several hours. This research aimed to determine how environmental factors influenced the COVID-19 virus's survival and behavior, as well as its transmission, in a complex environment. Based on the results, virus transmissions are influenced by various human and environmental factors such as population distribution, travel, social behavior, and climate change. Environmental factors have not been adequately examined concerning the transmission of this epidemic. Thus, it is necessary to examine various aspects of prevention and control of this disease, including its effects on climate and other environmental factors.

Photooxidation/adsorption of arsenic (III) in aqueous solution over bentonite/ chitosan/TiO2 heterostructured catalyst.

Arsenic contamination of the environment is a serious health hazard due to its toxicity and carcinogenic effects thus demanding developed and robust removal methodologies. In this study, bentonite/chitosan/titania (BT/CS-TiO2) was developed to boost photo-oxidation/adsorption efficiency while providing a low-cost and potential heterostructured platform for arsenic removal from aqueous media. Under UV irradiation, BT/CS-TiO2 heterostructured exhibited the desired capability (97%) of boosting oxidize toxic AsIII to minor toxic AsV. Results confirmed that •OH radicals available at TiO2 sites under UV light played a critical role in the proposed photo-oxidation process of AsIII. BT/CS exhibited a high adsorption capacity (160 mg g-1) for AsV removal due to its electrostatic interaction and surface complexation. Additionally, BT/CS-TiO2 heterostructured showed satisfactory recyclability with no considerable interferences in the presence of coexisting anions due to the suitability of the valence band position of TiO2 for the oxidation of AsIII as well as the presence of CS into BT layers. Thereby, the findings revealed that impregnation of TiO2 in BT/CS is a promising approach for arsenic removal.

Statistical modeling and optimization of Toluidine Red biodegradation in a synthetic wastewater using Halomonas strain Gb.

BACKGROUND: Synthetic dye wastewater is a group of environmental pollutants that are widely used in some industries like textile, printing, dyeing and etc. Traditional treatment methods for wastewaters containing synthetic dyes are considered as expensive and time consuming approaches due to the chemical stability of these pollutants. Therefore, in recent years, biodegradation by means of capable microorganisms has been considered as an effective way to remove these pollutants. Hence, the present study has aimed at examining the decolorization of Toluidine Red (C.I. no.12120), which is an oil soluble azo dye, as the sole sources of carbon and energy from a synthetic dye wastewater by the halophilic Halomonas strain Gb bacterium. In order to model, optimize, and investigate the individual factors affecting the biodegradation capacity of this dye by Halomonas strain Gb, for the first time response surface methodology (RSM) and central composite design (CCD) were applied. METHODS: In this research, statistical modeling and optimization were performed by Design Expert software version 10 and the degradation capacity was considered by carrying out 30 tests using RSM method. For this purpose, the effect of 4 variables included dye concentration (10-30 ppm), salt concentration (2-10%), pH (5.5-9.5), and temperature (20-40) at different times of 2nd, 4th, and 10th days have been studied. Then, a second-order function was presented for the amount of dye removal in terms of the four selected variables, based on statistical modeling. RESULTS: According to the obtained results and analysis of variance, all main variables were found to be significantly effective on the biodegradation capacity. With regard to the results, the highest amount of biodegradation between different days was 81% and observed at the 4th day, while the optimum conditions for the maximum biodegradation of this time has been determined at pH of 6.5, temperature of 35 °C, and salt and dye concentrations were equivalent to 4% and 25 ppm, respectively. There is 11% relative error between the experimental and predicted results in the selected experiments, which confirms the reliability of the obtained correlation for calculating the decolorization capacity. CONCLUSION: In accordance with the results, the proposed model can provide a good prediction of the effect of different conditions on the biodegradation of Toluidine Red, and the optimization results in this study have been consistent with the previous studies conducted with the IP8 and D2 strains by the OFAT method. Moreover, the proposed model may help in better understanding the impact of main effects and interaction between variables on the dye removal. Overall, the results indicated that the halophilic bacterium used in dye removal can be more effective in high-salinity environments.

Characterization of a lipase from a newly isolated Pseudomonas sp.

BACKGROUND AND OBJECTIVES: Lipases are valuable biocatalysts which are widely used in the detergent, food, dairy and pharmaceutical industries. The aims of the present study included the isolation of a lipase-producer from industrial zones and the partial characterization of the enzyme. MATERIALS AND METHODS: A number of bacteria were isolated from sites related to the oil industries. An isolate forming a halo zone in a selective medium (TW agar) was then selected and grown on a medium suitable for the production of lipase. The isolate was subsequently identified by the 16S rRNA sequencing method, and its enzyme activity was measured by a spectrophotometer using pNPP as a substrate. RESULTS: The selected isolate was identified by the molecular method as Pseudomonas sp. Its extracellular lipase activity was 41.5 ± 1.4 U/ml, and the high affinity of this enzyme for the substrate was indicated by the kinetic parameters of Km and Vm, which were estimated by the the Lineweaver-Burk plot as 0.77 mM and 49.5 U/ml, respectively. Activation energy of lipase calculated from the Arrhenius plot was found to be 20.78 kJ/mol, and a temperature coefficient (Q10) of 4.39 indicated the high catalytic activity of the enzyme and the temperature dependence of the enzymatic reaction. CONCLUSION: The results demonstrated that the indigenous isolate could have potential applications in many relevant industries.