Sharif Digital Repository

In this study the ability of Acidithiobacillus ferrooxi-dans, with regard to the biorecovery of heavy metals in shake flask has been investigated. Adaptation experiments with the single metal ions Ni, Co, V, Mo, W and a mixture of the first four metal ions in the medium was developed through serial sub-culturing. Adaptation showed that A. ferrooxidans could tolerate up to 2.3 g/l Ni, 1.4 g/l Co, 1.4 g/l V, 0.045 g/l Mo and 0.005 g/l W, singly. In the presence of multi-metals considering a mixture of Ni-Co-V-Mo, the bacteria was able to tolerate up to 1.5 g/l Ni, 0.8 g/l Co, 0.8 g/l V and 0.05 g/l Mo in steps of 50-100 mg/l for Ni, Co and V, while for Mo and W with increments in concentration... 

The synthesis of a new drug delivery system based on hybrid nanomaterials containing a β-CD core and hyperbranched PG is described. Conjugating PG branches onto β-CD not only increases its water solubility but also affects its host/guest properties deeply. It can form molecular inclusion complexes with small hydrophobic guest molecules such as ferrocene or FITC with reasonable release. In addition, the achievable payloads are significantly higher as for carriers such as hyperbranched PGs. Short-term in vitro cytotoxicity and hemocompatibility tests on L929 cell lines show that the hybrid nanomaterial is highly biocompatible. Due to their outstanding properties, β-CD-g-PG hybrid nanomaterials... 

In this study, superparamagnetic iron oxide nanoparticles (SPION) embedded by folic acid (SPION-folate) were prepared by a modified co-precipitation method. The structure, size, morphology, magnetic property and relaxivity of the SPION-folate were characterized systematically by means of XRD, VSM, HRSEM and TEM and the interaction between folate and iron oxide (Fe3O 4) was characterized by FT-IR. The particle size was shown to be ≈5-10 nm. To ensure biocompatibility, the interaction of these SPION with mouse connective tissue cells (adhesive) was investigated using an MTT assay. Consequently, gallium-67 labeled nanoparticles ([67Ga]-SPION-folate) were prepared using 67Ga with a high labeling... 

At present, nanoparticles are used for various biomedical applications where they facilitate laboratory diagnostics and therapeutics. More specifically for drug delivery purposes, the use of nanoparticles is attracting increasing attention due to their unique capabilities and their negligible side effects not only in cancer therapy but also in the treatment of other ailments. Among all types of nanoparticles, biocompatible superparamagnetic iron oxide nanoparticles (SPIONs) with proper surface architecture and conjugated targeting ligands/proteins have attracted a great deal of attention for drug delivery applications. This review covers recent advances in the development of SPIONs together... 

We previously reported that MR01, an indigenous strain of Pseudomonas aeruginosa, was able to produce a rhamnolipid-type biosurfactant. Here, we attempted to define the structural properties of this natural product. The analysis of the extracted biosurfactant by thin-layer chromatography (TLC) revealed the presence of two compounds corresponding to those of authentic mono- and di-rhamnolipid. The identity of two structurally distinguished rhamnolipids was confirmed by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. Liquid chromatography/mass spectrometry (LC/MS) of extracted biosurfactant revealed up to seventeen different rhamnolipid congeners. Further quantification showed... 

Background: Exposure-response information about particulate air-pollution constituents is needed to protect sensitive populations. Particulate matter <2.5 mm (PM 2.5) components may induce oxidative stress through reactive-oxygen-species generation, including primary organics from combustion sources and secondary organics from photochemically oxidized volatile organic compounds. We evaluated differences in airway versus systemic inflammatory responses to primary versus secondary organic particle components, particle size fractions, and the potential of particles to induce cellular production of reactive oxygen species. Methods: A total of 60 elderly subjects contributed up to 12 weekly... 

Background: Recent clinical studies of treating traumatic brain injury (TBI) with autologous adult stem cells led us to compare effect of intravenous injection of bone marrow mesenchymal stem cells (BMSC) and bone marrow hematopoietic stem cell mobilization, induced by granulocyte colony stimulating factor (G-CSF), in rats with a cortical compact device. Methods: Forty adult male Wistar rats were injured with controlled cortical impact device and divided randomly into four groups. The treatment groups were injected with 2 × 106 intravenous bone marrow stromal stem cell (n = 10) and also with subcutaneous G-CSF (n = 10) and sham-operation group (n = 10) received PBS and "bromodeoxyuridine... 

Needle insertion simulation and planning systems (SPSs) will play an important role in diminishing inappropriate insertions into soft tissues and resultant complications. Difficulties in SPS development are due in large part to the computational requirements of the extensive calculations in finite element (FE) models of tissue. For clinical feasibility, the computational speed of SPSs must be improved. At the same time, a realistic model of tissue properties that reflects large and velocity-dependent deformations must be employed. The purpose of this study is to address the aforementioned difficulties by presenting a cost-effective SPS platform for needle insertions into the liver. The study... 

A new dibenzothiophene (DBT) desulfurizing bacterium was isolated from oil-contaminated soils in Iran. HPLC analysis and PCR-based detection of the presence of the DBT desulfurization genes (dszA, dszB and dszC) indicate that this strain converts DBT to 2-hydroxybiphenyl (2-HBP) via the 4S pathway. The strain, identified as Rhodococcus erythropolis SHT87, can utilize DBT, dibenzothiophene sulfone, thiophene, 2-methylthiophene and dimethylsulfoxide as a sole sulfur source for growth at 30 °C. The maximum specific desulfurization activity of strain SHT87 resting cells in aqueous and biphasic organic-aqueous systems at 30 °C was determined to be 0.36 and 0.47 μmol 2-HBP min-1 (g dry cell)-1,... 

A bacterial strain was isolated and cultured from the oil excavation areas in tropical zone in southern Iran. It was affiliated with Pseudomonas. The biochemical characteristics and partial sequenced 16S rRNA gene of isolate, MR01, was identical to those of cultured representatives of the species Pseudomonas aeruginosa. This bacterium was able to produce a type of biosurfactant with excessive foam-forming properties. Compositional analysis revealed that the extracted biosurfactant was composed of high percentages lipid (∼65%, w/w) and carbohydrate (∼30%, w/w) in addition to a minor fraction of protein (∼4%, w/w). The best production of 2.1 g/l was obtained when the cells were grown on... 

A crude phenolic glycolipid extract from Mycobacterium bovis BCG was fractionated by column chromatography. A reversed-phase high performance liquid chromatography (HPLC) method with UV detection at 275nm was developed for simultaneous detection and separation of phenolic glycolipids (PGLs) in Mycobacterium bovis BCG. This analysis provides a good resolution. Different solvent systems and columns for HPLC were compared. A system composed of acetonitrile-water in the ratio of 0→80% at a flow rate of 0.8 mL/min and C8 analytical column were found to be optimum for HPLC of the phenolic glycolipids. This simple method is therefore appropriate to purify these compounds present in M. bovis extract... 

The performance of nanoparticles for biomedical applications is often assessed by their narrow size distribution, suitable magnetic saturation and low toxicity effects. In this work, superparamagnetic iron oxide nanoparticles (SPIONs) with different size, shape and saturation magnetization levels were synthesized via a co-precipitation technique using ferrous salts with a Fe3+/Fe2+ mole ratio equal to 2. A parametric study is conducted, based on a uniform design-of-experiments methodology and a critical polymer/iron mass ratio (r-ratio) for obtaining SPION with narrow size distribution, suitable magnetic saturation, and optimum biocompatibility is identified. Polyvinyl alcohol (PVA) has been... 

The volatile components of Iranian saffron were extracted using ultrasonic solvent extraction (USE) technique and then were separated and detected by gas chromatography-mass spectrometry (GC-MS). Variables affecting the extraction procedure were screened by using a 25-1 fractional factorial design and among them; sample amount, solvent volume, solvent ratio and extraction time were optimized by applying a rotatable central composite design (CCD). The optimum values of factors were: 2.38 g sample, 29.04 mL solvent, 69.23% MeOH solvent ratio and 71.8 min for the extraction time. Forty constituents were identified for Iranian saffron by GC-MS representing 90% of the total peak area. The major... 

Photodegradation of Escherichia coli bacteria in presence of Ag-TiO2/Ag/a-TiO2 nanocomposite film with an effective storage of silver nanoparticles was investigated in the visible and the solar light irradiations. The nanocomposite film was synthesized by sol-gel deposition of 30 nm Ag-TiO2 layer on ∼200 nm anatase(a-)TiO2 film previously doped by silver nanoparticles. Both Ag/a-TiO2 and Ag-TiO2/Ag/a-TiO2 films were transparent with a SPR absorption band at 412 nm. Depth profile X-ray photoelectron spectroscopy showed metallic silver nanoparticles with diameter of 30 nm and fcc crystalline structure were self-accumulated on the film surface at depth of 5 nm of the TiO2 layer and also at the... 

As the use of superparamagnetic iron oxide nanoparticles (SPION) in biomedical applications increases (e.g. for targeting drug delivery and imaging), patients are likely to be exposed to products containing SPION. Despite their high biomedical importance, toxicity data for SPION are limited to date. The aim of this study is to investigate the cytotoxicity of SPION and its ability to change cell medium components. Bare and poly(ethylene glycol)-co-fumarate (PEGF)-coated SPION with narrow size distributions were synthesized. The particles were prepared by co-precipitation using ferric and ferrous salts with a molar Fe3+/Fe2+ ratio of 2. Dulbecco's modified Eagle's medium (DMEM) and primary... 

The oxidation of ferrous iron (Fe2+) in solution using Acidithiobacillus ferrooxidans has industrial applications exclusively in the regeneration of ferric iron (Fe3+) as an oxidizing agent for the removal of hydrogen sulfide from waste gases, desulfurization of coal, leaching of non-ferrous metallic sulfides and treatment of acid mine drainage. The aim of this investigation was to increase the bio-oxidation rate of ferrous sulfate by using immobilized cells. Rate of Fe2+ oxidation was determined in a packed-bed bioreactor configuration with monolithic particles being used as support material. Biooxidation of ferrous iron by immobilized cells was investigated in repeated batch culture and... 

We report a new method of growing Mn-doped CdS (CdS:Mn) nanoparticles in an aqueous solution at boiling temperature. The idea is to use precursors that react only at high temperature, in order to gain crystalline luminescent nanoparticles. CdSO4, Mn(NO3)2 and Na 2S2O3 were used as the precursors, and thioglycerol was employed as the capping agent and also the reaction catalyst. Na2S2O3 is thermally sensitive and it releases S2- ions upon heating. The CdS:Mn nanoparticles obtained are about 4 nm in size and show both cubic and hexagonal crystalline phases with a ratio of 35% to 65%. The luminescence of nanoparticles contains a peak at 580 nm, which is related to Mn2+ ions. Prolonged reaction... 

The purpose of this study was to develop the structure-toxicity relationships for a large group of 268 substituted benzene to the ciliate Tetrahymena pyriformis using mechanistically interpretable descriptors. The shuffling-adaptive neuro fuzzy inference system (Shuffling-ANFIS) has been successfully applied to select the important factors affecting the toxicity of substituted benzenes to T. pyriformis. The results of the proposed model were compared with the model of linear-free energy response surface and also the principal component analysis Bayesian-regularized neural network (PCA-BRANN) trained using the same data. The presented model shows a better statistical parameter in comparison... 

In this study the effects of initial concentration of Fe(II) and Fe(III) ions as well as initial pH on the bioleaching of a low-grade sphalerite ore in a leaching column over a period of 120 days with and without bacteria were investigated. Four different modifications of medium were used as column feed solutions to investigate the effects of initial concentration of Fe(II) and Fe(III) ions on zinc extraction. The experiments were carried out using a bench-scale, column leaching reactor, which was inoculated with mesophilic iron oxidizing bacteria, Acidithiobacillus ferrooxidans, initially isolated from the Sarcheshmeh chalcopyrite concentrate (Kerman, Iran). The effluent solutions were... 

In this study isolated perfused rat muscle was used to examine the direct effect of temperature changes on the eccentric contraction-induced force and desmin loss. The left medial gastrocnemius muscle was separated and the entire lower limb was transferred into a prewarmed (35°C) organ bath. Temperature was adjusted to 31 or 39°C before and during eccentric contractions. Maximal isometric force and desmin loss were measured after 15 isometric or eccentric contractions. According to our data, organ bath temperature changes before or during eccentric contractions had no significant effect on force loss. However, a strong correlation between desmin loss and temperature changes before (r = 0.93,...