فهرست مطالب معصومه طباطبایی

The reaction of magnesium chloride and cadmium nitrate with benzene-1,2,4,5-tetracarboxylic acid in the presence of NaOH and in aqueous solution led to formation of 3-dimensional coordination polymer formulated as, [Cd(bta)Na(H2O)4Mg0.5].2H2O}n(1) (btaH4 = benzene-1,2,4,5-tetracarboxylic acid),. The crystal structure of 1 was determined by X-ray diffraction. The Single-crystal X-ray structure shows that the asymmetric unit of 1 consists of cadmium, sodium and magnesium in (1:1:0.5) ratio. Three metals cations are linked with oxygen atoms of benzene-1,2,4,5-tetracarboxylate.  Benzene-1,2,4,5-tetracarboxylate acts as bidentate and monodentate bridging ligand and causes to making trimetallic 3-dimentinal coordination polymer.

Ginger is a plant that is used as a drug for pain relieving and anti-inflammatory in traditional medicine, but conventional prescribing of it faces serious challenges. One way to overcome these problems is the loading of ginger extract in polymer carriers. The aim of this study was characterization and evaluation of the loading and releasing of ginger extract from hyaluronic acid nanocapsules for medical applications.

In this applied study, ginger extract as a pain-relieving drug was loaded in hyaluronic acid nanocapsules. The hyaluronic acid nanocapsules containing ginger extract were fabricated by emulsion method. The surface morphology, particle size and zeta potential, surface roughness and functional groups on the sample surface were evaluated by field emission electron microscopy (FESEM), dynamic light scattering (DLS), atomic force microscopy (AFM) and fourier transform infrared spectroscopy (FTIR), respectively. The stability and ginger release from nanocapsules were also determined via DLS and HPLC, respectively. The toxicity and fibroblast cells viability of ginger extract encapsulated in hyaluronic acid were evaluated by MTT assay. Data were analyzed by SPSS 16 Software. The t-Student test was performed for statistical comparison of data and statistically significant was P < 0.05.

The ginger entrapment efficiency (EE %) in nanocapsules was 74%.  The average particle diameter and charge surface of the samples were calculated 413 nm and -10 mV, respectively. The negative charge of samples showed the stability of samples without agglomeration. Therefore, the surface morphology of the samples was observed as relatively spherical particles. In vitro test showed 95% fibroblast cell growth and proliferation on nanocapsules compared to the control sample (P < 0.05).

The hyaluronic acid nanocapsules have a great potential for delivery of ginger extract in the area of pain and inflammation.

In recent years, with the shortage of conventional energy resources, there has been a great advancement in the study of fuel cells particularly hydrogen-methanol types as an important energy alternative. One of the main components in such fuel cells is an electrolyte membrane whose main function is to carry protons and capture methanol. The electrolyte membrane must have a high chemical and electrochemical stability plus mechanical resistance. In addition, high proton conductivity is required to support better fuel cell performance.

In this research, novel nanocomposite membranes were prepared as electrolyte for application in fuel cells. For this purpose, two types of membranes, including sulfonated polyethersulfone (SPES) and its blend with polyurethane (PU), were chosen as base membranes. At first, polyethersulfone was sulfonated by using sulfonic acid and blended with PU. Then, silica nanoparticles with different percentages (3, 5, and 8 wt%) were added to blend membrane (SPES/PU/SiO2). The prepared membranes properties were studied by Fourier transform spectroscopy (FT-IR), X-ray diffraction analysis, thermogravimetry (TGA), water and methanol uptake test, proton conductivity test and scanning electron microscopy (SEM).

The results suggested that there was a proper distribution of PU into the prepared membrane through forming hydrogen bonds between polar groups of SEPS and PU. Hence, by the mechanism of increasing polarity, the conductivity in SPES/PU blend membrane was increased (74%), comparing to its pure samples without intense increase in water and ethanol uptake. Additionally, by adding the silica nanoparticles to a SEPS/PU blend membrane and forming SPES/PU/SiO2 nanocomposite membrane, these particles formed a higher adhesion between the phases by forming covalent bonds with sulfonic acid groups of SPES and forming hydrogen bond with polar groups of PU and SPES. As a result, the morphology was modified by the mechanism of decreasing cavities and voidages. Finally, the conductivity of SPEC/PU/SiO2 nanocomposite membrane compared to that of the SPES pure sample increased by 53.13% only by an increase of 11% and 8% in water and methanol uptake, respectively.

The ion mobility spectrometry (IMS) is an analytical technique that is widely used due to its high sensitivity and speed for the detection of ionized molecules in gas phase and under atmospheric pressure. Breath analysis is a new method for obtaining information about person's clinical conditions that is considered by researchers. Human exhaled air contains a variety of components such as water vapor, hydrogen, acetone which in case of disease changes the amount of them. Some of these substances are highly related to diseases like asthma, lung cancer, diabetes. In this research work, the detection and measurement of acetone in breath of diabetics is described using an ion mobility spectrometer with a corona-positive ionization source.

Instrumental parameters such as cell and injection temperatures, drift and corona voltages, carrier and drift gas flow rates, and pulse width were investigated. Under optimum conditions, calibration curve and other figures of merits were determined. Under optimum conditions, the breath of diabetics were sampled by syringe and then injected to IMS.

Under optimum experimental conditions, the calibration curve was linear in the range of 10-80 ng. The relative standard deviation for 20 and 50 ng of acetone with 6 times the measurement were 7.2 and 6.2%, respectively. The limits of detection and quantification were 2.7 and 9 ng, respectively. The developed method has been used satisfactory to determine of acetone in the breath of diabetics.

The reaction of 2-hydroxy-3-methoxybenzaldehyde with 4-nitrosulfonylhydrazide under refluxing led to co-crystalline compound contains N'-(2-hydroxy-3-methoxy benzylidene)-4-nitro benzenesulfonylhydrazide (a sulfonamide-Schiff base compound) and 1,2-bis (2-hydroxy-3-methoxy-benzylidenehydrazine) (I). A medium strong hydrogen bonds in 1 links the oxygen atoms of one molecule of 1,2-bis(2-hydroxy-3-methoxy-benzylidenehydrazine) to the NH group of the N'-(2-hydroxy-3-methoxy benzylidene)-4-nitrobenzenesulfonylhydrazide and is responsible for establishing of co-crystals. Compound 1 was characterized by NMR and IR spectroscopy, elemental analysis and single crystal X-ray diffraction method. Crystallographic data for 1 was collected at 95 K. The synthesized compound has been crystallized in monoclinic system with P21/n space group and a = 6.6771(2) Å, b = 19.2072(6) Å, c = 17.3980(1) Å, β = 95.56(3)º cell parameters. The final R value is 0.037 for 07 independent reflections.

A nickel complex with pyridine-2,6-dicarboxylic acid formulated as [Ni(pydcH)2].3H2O was synthesized and its crystal structure determined with single-crystal X-ray at diffraction temperatures (296 K and 120 K). Pyridine-2,6-dicarboxyli acid deprotonated on one group of COOH and two pydcH- anion is coordinated to Ni(II) atom as a tridentate ligand forming a distorted octahedral environment. The phase transition in crystal system is obtained with differ in temperature. The title compound is crystallized in monoclinic system with P21/c space group at 296 K, while it is crystallized in triclinic system with CAWT IMAGE space group at 120 K.

2,4-Dichlorophenoxyacetic acid (2,4-D) is a widely used acidic herbicide with high toxicity. So, this study was performed with the aim of investigation of 2,4-D photochemical oxidation by persulfate and UV.
This study was performed in bench scale and batch condition. K2S2O8 was used as oxidant in presence of UV. In this study, effects of pH, oxidant concentration, contact time and initial concentration of 2, 4-D on the process were examined in batch experiments. The concentration of 2, 4-D was determined using spectrophotometer at 285 nm.
The best results were achieved at acidic conditions (pH =3). Increasing dosages of persulfate and contact time increased the degradation of 2,4-D. However, an increase in initial 2,4-D concentration resulted in decreasing of photochemical oxidation efficiency. The maximum photochemical oxidation efficiency of 2,4-D was 96 % for a 2.5 mg/l persulfate, 10 mg/l 2,4-D, pH value of 3.0 and contact time of 240 min. The degradation of 2, 4-D by persulfate is found to follow the pseudo-first-order kinetic model (R2=0.979).
In this study, 2,4-D was effectively degraded in aqueous solutions by the photochemical oxidation using S2O8/UV. From this study, it seems that photochemical oxidation with S2O8/UV can be an effective process for the treatment of contaminated water with 2, 4-D.

N'-(2-hydroxy-3-methoxybenzylidene)-4-methylbenzenesulfonohydrazide (1) was prepared by the reaction of p-Toluenesulfonyl hydrazide and 2-hydroxy-3-methoxy benzaldehyde (1:1 molar ratio) in ethanol under reflux condition. The crystal structure of the compound was determined by X-ray crystallography. Crystal data for 1 at -100 K: space group C/2c with: a = 15.807(1) Å, b = 10.457(1) Å, c = 20.779(1) Å, β = 109.68º (1). The final R value is 0.0574 for 3155 independent reflection. The N -H …O hydrogen bond converts the molecules into an infinite chain along [010].

A variety of pesticides is used to combat weeds. Check-resistant residues of contaminants in drinking water resources have detrimental effects on human health and on environment. In recent years, advanced oxidation methods o remove toxins from the environment, particularly the aquatic environment is further considered.
In this study, samples adding different concentrations (mg/L10, 20, 30) of pesticides were prepared in deionized water. Specimens of the individual phases in a batch reactor with the catalyst (g / L 1 ,2, 3 and, 4), pH (3,5, 7, 9, 11) and contact time (60, 120, 180, 240 min) exposure contacts coupled Ag / ZnO and UV-c was performed.
The results showed a reduction in pesticide concentrations (2, 4-D) and increasing the reaction time, the degradation efficiency increases. The highest degradation efficiency was for 240 minutes and the initial concentration of toxin was (2, 4-D) 10 mg/L to 96 percent. The kinetics of the elimination of toxins (2, 4-D) by the process of photocatalytic Ag / ZnO in the presence of UV-C light corresponded to the pseudo first.
The most effective degradation of toxins (2, 4-D) by the process of photocatalytic Ag / ZnO under conditions of neutral pH and with increasing reaction time and reduce toxin concentrations (2, 4-D) is the result.

Antimony trioxide (Sb2O3) has been utilized as a catalyst in polyethylene terephtalate (PET) production, and the studies conducted on the bottled water has demonstrated that antimony can be leached from PET bottles into drinking water. In this study, a simple method was applied in order to determine the trace amount of antimony in bottled drinking water based on preconcentration /solid phase extraction. The nano alumina modified with Schiff base ligand was used in regard with Sb preconcentration. The experiments were performed in a continuous system and HCI was used as eluent of Sb ion. Several chemical and flow variables were optimized for a quantitative preconcentration and determination of Sb ion. The atomic absorption spectroscopy was used to determine Sb ion concentration. In order to study the keeping conditions on the leaching of Sb ion from PET plastic, drinking water bottles were kept in different conditions(room temperature, sunny light and -18˚C). The calibration graph was linear in the range of 0.5 to 15.0 ppm Sb with detection limit of 0.055 ppm. The flow rate of sample was optimized in range of 1.0-9.0 mLmin-1 and Sb ion can be quantitatively eluted at 90 Vsample: Veluent retio. The study results revealed that the modified nano alumina is an effective sorbent in regard with absorbing Sb ion from water and HCI 1M can be used as an appropriate eluent. Maximum leaching of Sb ion is observed when the bottled drinking water was exposed to the sun light.

In this research mixed ZnO and TiO2 was used for degradation of an azo dye (Direct Blue 71). In comparison with just TiO2 or ZnO as photocatalyst, mixed photocatalyst (ZnO/TiO2) is more efficient catalyst for degradation of dye under UV irradiation. The progress of the reactions was monitored spectrophotometrically by measuring the absorbance of dye at special wavelengths. The effects of various parameters such as ZnO/TiO2 ratio, amount of photocatalyst, pH,initial dye concentration and irradiation time on decolorization rate were systematically investigated. Results show that approximately 90 % of Direct Blue 71 has been eliminated after 70 minutes and optimized condition.

The heavy metals are the most important pollutants their concentration of which in the environment is increasing in connection with cities and industrials development. One of these metals is chromium which، in the trivalent and Hexavalent oxidation state، is used in industries such as electroplating، glass، ceramic، tannery and leather. Hexavalent Chromium has proven several health hazards such as being carcinogenic. The aim of this study was to investigate nano-alumina modified with Schiff base ligands in removal of hexavalent chromium from aqueous solution in acidic conditions. This study is experimental which was performed in batch reactor at 20 ° C temperature to investigate the effect of initial chromium concentration، adsorbent dose and reaction time on removal of chromium by nano-alumina. For adsorbent preparation، nano-alumina was purchased from Nano Kimia Pajoh company، and for increasing adsorption power، it was modified with Schiff base ligands in the presence of proper surfactant. The study was performed on the synthetic samples containing 2 and 5 mg/L concentration of chromium. The unknown concentration of Hexavalent Chromium was detected by spectrophotometer set (UV/VisibleSP-3000 Plus-Japan) at 540 nm. According to the results، removal efficiency increases with increasing adsorbent dose and reaction time and decreases with increasing initial concentration of chromium. Results of this study indicated that Hexavalent chromium adsorption by nano-Alumina modified with Schiff base ligands reaches equilibrium at 30 minutes and maximum capacity will be obtained. The maximum removal efficiency، and adsorption capacity in optimum conditions (adsorbent dose=0. 1mg/L، pH=3)، with chromium initial concentration of 5mg/L at 180 minute، were 83. 4% and 4. 17 mg/L respectively. Nano-alumina modified with Schiff base ligands is an effective adsorbent in removal of hexavalent chromium from aqueous solution.

The application of laser in dentistry has gained special attention in caries removal, cavity preparation and surface modification to obtain best adhesion of restorative materials to dental tissue. The aim of this study was to compare the microleakage of composite restoration in occlusal and cervical parts of cavities prepared by Er:YAG laser and diamond bur. 12 human caries free third molars were selected for this study. Then, the teeth were randomly divided in 2 groups of 6 in each. The class V cavities were prepared on both buccal and lingual side of each teeth by Er:YAG or diamond bur. After etching and bonding procedure, the cavities were restored by composite resin incrementally and light cured for 40 sec. All tooth surfaces were coated with two layers of nail varnish leaving 1mm wide border around restoration margins. Then, the samples were immersed in 2% methylene blue solution. After 24 hours, they were washed and dried. The samples were bisected longitudinally into two equal buccal and lingual halves. Then, samples were assessed by using a light microscope. The extent of dye penetration in occlusal and cervical part was analyzed by Kruskal-Wallis. There was no significant difference in 2 groups. Regardless of the method of cavity preparation (Er:YAG laser or diamond bur) the microleakage of class V cavities in cervical part was significantly more than those in occlusal part.