Sharif Digital Repository

This study was designed to compare one-step, two-step and spent medium bioleaching of spent catalyst by adapted Aspergillus niger in batch cultures. Aspergillus niger, which was adapted to heavy metal ions, Ni, Mo, Fe, and W, was grown in medium containing up to 5% (w/v) of spent catalyst. The main lixiviant in bioleaching was gluconic acid, which was produced at all pulp densities in the one-step bioleaching process. Gluconic acid was also produced in the two-step bioleaching process when the spent catalyst was present at pulp densities greater than 1% (w/v). In the spent medium leaching, however, the primary agent was citric acid. The pulp density of the spent catalyst was varied, and this... 

A novel recognition method for selective determination of the hyoscine N-Butyl bromide (HBB), an antispasmodic agent for smooth muscles, was devised using extended gate field-effect transistor (EG-FET) as transducing unit. For this purpose a PVC membrane, containing hyoscine n-butyl-tetraphenyl borate ion-pair as recognition component, was coated on Ag/AgCl wire, which was connected to the extended metal gate. In optimal conditions, the linear range for HBB was 10-8-10-5 molL−1 with limit of detection 1.7×10-9 molL-1. The proposed sensor was applied in real sample, it showed fast response with high accuracy, and therefore it could be used as HPLC detector in the pharmaceutical samples in... 

Lake Urmia, which was once the second-largest saline lake in the world, has been shrinking dramatically. Moreover, Lake Urmia has become supersaturated with total salinity averaging more than 350 g/l. Salt precipitation and dissolved materials brought by inflowing rivers have formed a layer of sediment with low hydraulic conductivity on the lakebed. Considering the flat bathymetry of Lake Urmia, we conducted a series of numerical simulation scenarios to study the groundwater flow pattern in the vicinity of the hypersaline Lake Urmia using COMSOL Multiphysics®. In the first step, we performed the simulations in steady-state conditions. Secondly, we simulated the lake level fall in 10 years at... 

Purpose: Drowsy driving accounts for many accidents and has attracted substantial research attention in recent years. Electroencephalography (EEG) signals are shown to be a reliable measure for the early detection of drowsiness. Unfortunately, there is no comprehensive study showing the applicability of drowsiness detection systems with EEG signals. In this research, we targeted the studies under the category of drowsiness detection, which adopted an EEG-based approach, to inspect the applicability of these systems from different aspects. Materials and Methods: We included documented studies that utilized clinical devices and consumer-grade EEG headsets for detection of drowsiness and... 

Investigating the dynamic evolution of storage volume and salinity of Lake Urmia (LU), which is crucial to present more reliable estimations of water balance components, needs to be furthur studied. We aimed to fill this gap by developing a coupled lumped mathematical model that considered the two-way effect of salt and water balance components on each other. Through the coupled water and salt balance model, salt precipitation and dissolution components were incorporated, and vaporation was calculated dynamically based on the lake's salinity. The final model was then used as a tool to estimate the groundwater flux. Results indicated that during the lake shrinkage period (2009–2015),... 

In this study, nanostructured biodegradable pure Zn, Zn-4 wt. % Mn and Zn-24 wt % Mn alloys were produced by 20 h mechanical alloying and consequent cold pressing and sintering. Structural evolutions were investigated using the X-ray diffraction technique. Also, the microstructure was characterized by scanning electron microscopy. The effects of alloy composition on density, mechanical properties, corrosion behavior in Hank's solution, cell viability and cell attachment were investigated. Crystallite size of the synthesized alloys after 20 h of milling reached to less than 40 nm and remained less than 80 nm after consolidation and sintering for 1 h. Alloys contain MnZn13 as second phase... 

N-annulated perylene based materials show outstanding and tunable optical and physical properties, making them suitable to be charge transport materials for optoelectronic applications. However, this type of materials has so far not been well studied in solar cells. Here, we develop a new hole transport material (HTM), namely S5, based on perylene building block terms, for organic-inorganic hybrid perovskite solar cells (PSCs). We have systematically studied the influences of the film thickness of S5 on their photovoltaic performance, and a low concentration of S5 with a thinner HTM film is favorable for obtaining higher solar cell efficiency. S5 shows excellent energy alignment with... 

This study aimed to preconcentration of sulfamethoxazole (SMX) in water and biological samples. Ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) and ultrasound-assisted dispersive solid-phase microextraction (UA-DSPME) methods paired with spectrophotometry were applied to extraction and preconcentration of SMX. ZnFe2O4 nanoparticles were prepared as adsorbent in UA-DSPME method by hydrothermal method. The scanning electron microscopy (SEM) technique showed that the adsorbent had symmetrical, bullet-shaped particles with uniform size. The results of the X-ray diffraction (XRD) showed the successful synthesis of the ZnFe2O4 nanoparticles. Effective parameters in... 

In this study, polystyrene was functionalized with Meldrum's acid toward the introduction of the ketenes (C=C=O) system to its backbone for producing a dramatically reactive intermediate. Meldrum's acid, as a ketene source, was reacted by poly(styrene-co-p-chloromethyl styrene) through a simple nucleophilic reaction to synthesize poly(styrene-co-styryl Meldrum's acid). Then, the pendant Meldrum's acid under thermal treatment converted to ketene intermediate resulting in highly reactive polystyrenes derivatives, which rapidly reacted by nucleophilic reagents to afford ultimate organic building blocks. The polystyrene derivatives were characterized using elemental analysis, FT-IR,... 

Carbazole compounds are p-type hole-transporting materials (HTMs) useful for perovskite solar cells (PSCs). In this work, we developed a new class of carbazol based HTMs; non-fused 3-D asymmetric structures (S14 and S12) as HTM of PSCs. To the best of our knowledge, there is no report on non-fused HTMs with a high glass transition temperature (Tg = 165 °C), which reduces crystallization and suppresses grain boundaries in glassy film, resulting in long-term durability. Experimental results show that tuning the carbazole moiety in S14 structure has a constructive influence on geometrical alignment, hole mobility, hydrophobicity, stability as well as efficiency. The resultant power conversion... 

The biological identity of nanoparticles (NPs) is established by their interactions with a wide range of biomolecules around their surfaces after exposure to biological media. Understanding the true nature of the biomolecular corona (BC) in its native state is, therefore, essential for its safe and efficient application in clinical settings. The fundamental challenge is to visualize the biomolecules within the corona and their relationship/association to the surface of the NPs. Using a synergistic application of cryo-electron microscopy, cryo-electron tomography, and three-dimensional reconstruction, we revealed the unique morphological details of the biomolecules and their... 

It is well understood that patients with different diseases may have a variety of specific proteins (e.g., type, amount, and configuration) in their plasmas. When nanoparticles (NPs) are exposed to these plasmas, the resulting coronas may incorporate some of the disease-specific proteins. Using gold (Au) NPs with different surface properties and corona composition, we have developed a technology for the discrimination and detection of two neurodegenerative diseases, Alzheimer's disease (AD) and multiple sclerosis (MS). Applying a variety of techniques, including UV-visible spectra, colorimetric response analyses and liquid chromatography-tandem mass spectrometry, we found the corona-NP... 

Engineered nanoparticles are increasingly being considered for use as biosensors, imaging agents and drug delivery vehicles. Their versatility in design and applications make them an attractive proposition for new biological and biomedical approaches. Despite the remarkable speed of development in nanoscience, relatively little is known about the interaction of nanoscale objects with living systems. In a biological fluid, proteins associate with nanoparticles, and the amount and the presentation of the proteins on their surface could lead to a different in vivo response than an uncoated particle. Here, in addition to protein adsorption, we are going to introduce concept of cell "vision",... 

In vivo dose-dependent effects of nanoscale graphene oxide (NGO) sheets on reproduction capability of Balb/C mice were investigated. Biodistribution study of the NGO sheets (intravenously injected into male mice at dose of ∼2000 μg/mL or 4 mg/kg of body weight) showed a high graphene uptake in testis. Hence, in vivo effects of the NGO sheets on important characteristics of spermatozoa (including their viability, morphology, kinetics, DNA damage and chromosomal aberration) were evaluated. Significant in vivo effects was found at the injected concentrations ≥200 μg/mL after (e.g., ∼45% reduction in sperm viability and motility at 2000 μg/mL). Observation of remarkable DNA fragmentations and... 

Asian red ginseng was used for green reduction of chemically exfoliated graphene oxide (GO) into reduced graphene oxide (rGO). The reduction level and electrical conductivity of the ginseng-rGO sheets were comparable to those of hydrazine-rGO ones. Reduction by ginseng resulted in repairing the sp 2 graphitic structure of the rGO, while hydrazine-rGO showed more defects and/or smaller aromatic domains. The ginseng-rGO sheets presented a better stability against aggregation than the hydrazine-rGO ones in an aqueous suspension. Whilst the hydrophobic hydrazine-rGO films exhibited no toxicity against human neural stem cells (hNSCs), the hydrophilic GO and ginseng-rGO films (as more... 

Vigorous debates have taken place within and between many countries about regulatory policy regimes covering the assessment and approval of genetically modified (GM) crops. In Iran, a very vigorous and hotly contested policy debate concerning legislation covering GM crops occurred between 2004 and 2009, but it was confined within government circles with almost no public discussion. This paper analyses the Iranian policy-making process in the period 2006-9. It explains how and why a stalemate arose in disputes between ministries and departments. The chosen analytical framework draws mainly on the regulation of technological risks and the analysis of public policy-making. It deploys the...