جستجوی مقالات مرتبط با کلیدواژه "xrd" در نشریات گروه "زیست شناسی"

Biological cementation is a new process in which urea hydrolysis bacteria or free urease enzyme decompose urea and increases the pH of the environment and chemical interactions in the presence of calcium ions to form calcite. Nowadays, nano-calcite is widely used in engineering, such as increasing the strength of soil and concrete, as well as in medicine, such as drug delivery and cancer treatment. This study aimed to investigate the laboratory conditions for producing nano-calcite particles with appropriate quality, size and purity by Sporosarcina pasteurii enzyme extract for use in medical and engineering studies. This investigation aimed to make calcite by S. pasteurii enzyme extract and optimize influential factors in calcite production. For this purpose, the bacterium S. pasteurii was cultured in nutrient broth containing urea and nickel, and upon reaching the appropriate time, the cells were separated and washed. Then, their enzyme extract was prepared by sonication, and calcite precipitation was studied in different amounts of urea, calcium chloride, enzyme and temperature. The quality of produced calcite crystals and their ratio compared to other crystals were investigated by XRD and SEM analyses. According to the results of XRD analysis, it was found that in 0.5 M urea and 0.25 M calcium chloride, the highest amount of calcite is produced with 96%, and the least side products are produced. Examining the particle size histogram in the sample containing 0.5 M urea and 0.25 M calcium chloride revealed that the range of particles were between 50 and 100 nm. The nature and type of crystals were studied by electron microscopy, and EDX analysis showed the presence of calcium, oxygen, and carbon. According to the results, it was found that by the increase of the concentrations of urea and calcium, the range of particle size became larger. Also, the percentage of calcite produced in low urea and calcium chloride concentrations is higher than those in high concentrations.

Silver nanoparticles (Ag-np) have high penetration and antimicrobial effect due to their high    surface-to-volume ratio. The aim of this study was to biosynthesize silver nanoparticles with red algae extract, Gracilaria gracilis, and to investigate their antibacterial activity against a number of standard and drug-resistant pathogenic bacteria.  First, Ag-np were synthesized. To confirm the structure and size of Ag-np, was used X-Ray diffraction spectroscopy, FE-SEM electron microscopy, and X-ray energy dispersive spectroscopy (EDS). The antimicrobial effects of algae extract on bacteria were determined by sequential dilution method. The size of nanoparticles under electron microscopy was between 12 and 46 nm. The nanoparticles were able to inhibit most of standard and antibiotic resistant bacteria, Ag-np at a concentration of 29 μg /ml, on the standard bacteria: S. typhimorium, E. coli, K. pneumonia and the clinically resistant bacteria, E. coli and           K. pneumonia, they had the most inhibitory effect. In contrast, standard and clinically resistant isolates of S. aureus and    standard strain S. pneumonia were resistant to Ag-np. The results of this research showed that the G. gracilis red algae as a bio-source that can be useful for green synthesis of silver nanoparticles at very low cost applications, these nanoparticles can be used as candidates for drug composition.

 In recent years, science and industry have focused on preparing nanoparticles based on the principles of green chemistry. For this purpose, various types of biological structures such as bacteria, yeasts, and string molds are used. Due to the resistance of bacteria to antibiotics, the need to replace effective antimicrobials, with fewer side effects is less. The aim of this research was to synthesis the iron oxide nanoparticles by lactobacillus fermentum cytoplasmic extract and investigate its antimicrobial effects against Staphylococcus aureus and Pseudomonas aeruginosa.

In this study, after preparing cytoplasmic extract of Lactobacillus fermentum from frees-thow method, iron sulfate solution 10-3 M were added and incubated for 3 weeks in the presence of 5 % carbon dioxide. Production of nanoparticles was investigated by X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) and finally, the antimicrobial effects of standard strains of two bacteria (Staphylococcus aurous and Pseudomonas aeruginosa) were determined using agar diffusion method.

Changing the color of solution to black is an indication of iron oxide nanoparticles production. The formation of iron oxide nano-crystals by Lactobacillus fermentum cytoplasmic extract was shown by XRD analysis and the average nanoparticles sizes that determined by transmission electron microscopy TEM were found to be about 10-15 nm with a spherical shape. The mean diameter of the no-growth field indicates that the synthesized nanoparticles inhibit Staphylococcus aureus in concentrations of 100 and 1000 mg/ ml, while are ineffective against  Psedumonas aeruginosa.

The use of cytoplasmic extract of Lactobacillus fermentum can be introduced as an effective biological method for the production of iron oxide nanoparticles and with more studies in this area, green nanoparticles may be used as suitable candidates for the treatment of microbial infections.

The castor plant )Ricinus communis L.) belongs to the Euphorbiaceae family and is a very important medicinal plant. Carbon nanotubes act as regulator of germination and growth of plant; and are able to change the morphology and physiology of plant cell.Penetration of carbon nanotubes in plant systems are able to change metabolic acts that lead to increase products . XRD and nanoparticle sizer experiments showed that the major phase is carbon and its size is range of 35-300 nm. The aim of this study is to investigate the effect of concentrations of multi-walled carbon nanotubes (MWCNTs) (0 and 500 µg ml-1 ) alongside the control under laboratory conditions on the characters of histology and ultrastructure. The vegetative growth was done in greenhouse conditions .foliar spray 500 µg ml-1 treatment (MWCNTs and deionezed water for 0 treatment) was done. Duration of experiment was 45 days. after that plant was exited from soil, shoot and root were seprated.process of preparation was done and samples go over on grid for study TEM.The result of ultra strcture studies of root and leaf showed, there is great aggregation of multi-walled carbon nanotubes with different length in vacuole and cytoplasm which in leaf cells have aggregation of vacuole and increase of plastogloboly in stroma of chlroplast and transformation of chloroplast from globular to ellipsoid and in root cells lead to destruction of mitochondria crista, vacoule and nucleus membrane and low chromatins, also was observed aggregation of vacuole and many diameter of sclreid and xylem wall.

Heavy metals are environmentally sustainable and durable pollutants that have become a world problem. As microorganisms show high resistance to heavy metals and can purify the environment and produce nanoparticles, the present study was designed to produce copper nanoparticles from copper-resistant bacteria isolated from wastewater of two copper workshops in Isfahan.
In this cross-sectional study, wastewater samples were collected from two copper workshops in Isfahan. The physicochemical factors of the wastewater, the minimum inhibitory concentration of bacteria (MIC) to copper and their resistance to several antibiotics were investigated. Morphological, biochemical and molecular identification tests were carried out on samples. Then the biomass of copper-resistant bacteria was added to the copper sulfate pentahydrate stock (CuSO4.5H2O) and the results were evaluated by Ultraviolet-Visible
spectrophotometer (UV-VIS), X-ray diffraction (XRD) and Transient Electron Microscopy (TEM).
Among the studied bacteria, the Bacillus toyonensis strain NE2 with the MIC of 3.5 mM and Arthrobacteragilis NE1 with MIC of 4 mM from copper workshop 2 and Stenotrophomonas maltophilia strain 5633 with the MIC of 6 mM from copper workshop 1 were isolated. Among these isolates, only S. maltophilia strain 5633 was able to synthesize copper nanoparticles. Peaks created in the range of 250-430 nm confirmed the presence of Copper (Cu) and Copper Oxide (CuO) particles.
The findings of this study showed that the isolated bacteria could be a good candidate to remove copper from wastewater and to biosynthesize copper nanoparticle.