Sharif Digital Repository

In recent years, studying of biological tissues by mass spectrometry imaging (MSI) has been considered due to its selectivity in identifying different compounds in biological tissues, no need for sample preparation, and the possibility of creating the distribution map of these compounds. The complexity of biological tissues due to their heterogeneity, the large volume of data generated, and the effects of competition of other species for ionization in MSI experiments have doubled the importance of using chemometrics to interpret these data. The aim of this work is to quantitatively study Chlordcone as a carcinogenic pesticide and to extract its spatial distribution pattern in mouse liver... 

Progress in analysis of multicomponent mixtures and processes focused on the interpretation of the multivariate responses, rely on the combination of sophisticated instrumental techniques and suitable chemometric methods. Among the present chemometric method, curve resolution techniques have a wide application in the analysis of multicomponent mixtures and processes. Chemometric resolution techniques are used in the present work. At the first, Essential oil of green and black cardamoms was extracted by hydrodistillation and was analyzed by gas chromatography–mass spectrometry (GC-MS). Due to the fact that the essential oils are complex mixtures, strong overlap is observed between the peaks.... 

In recent years, comprehensive two-dimensional gas chromatography (GC×GC) has been widely used, especially in the separation and measurement of complex mixtures, due to its features such as higher peak capacity and better resolution in separation than usual chromatography methods, which the mixture analysis of polycyclic aromatic hydroarbons (PAHs) compounds have been targeted in this study. One of the main challenges in this field is the large amount of data and the qualitative and quantitative interpretation of the resulting data. Therefore, the identification, separation and quantitative measurement of species in this field is important, especially in the presence of interference in the... 

The use of hyperspectral images to detect food fraud has become popular and it is necessary to develop chemometrics methods for analyzing the data from these images. Additionally, food authenticity has become a major challenge, and the focus of this thesis is on developing multivariate methods in chemometrics to extract useful information from data obtained from food authenticity verification using hyperspectral imaging (HSI). This thesis consists of six chapters. In the first chapter, a brief introduction to the fundamentals of hyperspectral imaging and food authenticity verification is presented. In the second chapter, the data structure of these images and chemometric methods including... 

In recent years, with increasing spills of oil and related petroleum products in the marine environment , the need for source identification of crude oil is increasing rapidly. Oil spill can have serious biological and economic impacts. There are many oil tankers on the surface of the sea and 0.68х109 kg crude oil spilled into soil per year . The source identification of oil spills can be a considerable challenge so these studies analytically and environmentally are important. The purpose of this study was to provide an update of the state-of-the-art of oil fingerprinting techniques to demonstrate the use of a rapid, inexpensive and useful technique for distinguishing between crude oils. In... 

Recently, the use of mass spectrometry imaging (MSI) has been introduced as a powerful tool to study the compounds in biological and environmental samples. The lack of need to sample preparation have made it possible to quantify and qualify these compounds in complex matrix such as biological matrices. This technique will also allow analyzing the compounds in a very wide mass range and precise structural information this method gives leads to employ this method widely for quantification and qualification of wide variety compounds. Accuracy and precision of results obtained by this method beside unique information it gives about system lead to wide use of this method in scientific... 

The present research devoted to the application, development and implementation of clustering, classification and regression techniques for modeling of the biological activity of different drug and drug-like molecules. At first, the prediction ability of Bayesian regression techniques was evaluated for describing and predicting the inhibition behavior of Integrin antagonists. As a next step, the complementary local search techniques have been used for improving the performances of Bayesian regularized genetic neural network (BRGNN) algorithm. The results indicated that the pattern search algorithm has a great potential to be used as a feature selection method in Chemoinformatics. In line... 

Factor analysis based methods are one of the applied methods in the Chemometrics. In this regard, some modifications on one of the factor analysis based method named fixed size moving window evolving factor analysis were done and two new methods named variable size moving window evolving factor analysis and preselected variable size moving window evolving factor analysis were introduced. The performance of the new introduced methods were examined and compared by the fixed size moving window evolving factor analysis.
Pure variable selection methods are useful for curve resolution methods which need to define an initial estimate from chromatographic profile or spectra. In this aspect the... 

Our lives are redefined by the constant emergence of new products that are easier, smarter and faster to use than their predecessors. Enabling this evolution are advances in miniaturization that have produced smaller mechanical, optical, and electronic products and devices. In the field of analytical chemistry, portable and handheld devices are now commercially available for a wide range of spectroscopic techniques. One of the most important applications of portable spectroscopic devices is in determining the authenticity of food. Nowadays, the development of a low-cost, fast and non-destructive method that can be implemented in the entire food supply chain has become a research field of... 

The purpose of this study was to investigate the capability of Isotopic Ratio Mass Spectrometry (IRMS) in the detection of four common natural plant frauds in saffron, namely Marigold flower, Safflower, Rubia and Saffron Style. For this purpose, first natural saffron isotopes were analyzed and used to investigate fingerprints of carbon-13 and nitrogen-15 isotopes by Elemental Analyzer Isotopic Ratio Mass Spectrometry (EA-IRMS) and carbon-13 isotopic ratio of saffron components by Gas Chromatography Isotopic Ratio Mass Spectrometry (GC-C-IRMS). Then, according to the isotopic behavior of the original saffron, they were sampled to form a mixture of saffron that is representative of the... 

Ionic liquids due to their unique physical and chemical properties are widely used in various fields of chemistry and chemical engineering. Determining properties of ionic liquids can be difficult, time consuming or even impossible. In first step of this study the IL thermo database was chosen as source of experimental data of ionic liquids. Viscosity, density, surface tension and melting temperature of ionic liquids based on bis(trifluoromethylsulfonyl)imide anion with cations imidazolium, pyridinium, pyrrolidinium, piperidinium and ammonium were modeled using QSPR approach. Linear and nonlinear models were built by means of multiple linear regression (MLR), multilayer perceptron neural... 

Today, with increasing concerns about the health of food and its effects on human health, ensuring the quality of food has become a big challenge for regulatory institutions. This issue is more important in the case of foods that have high nutritional and economic value. Among different food items, saffron is especially important due to its low production rate and high economic value. In this research, a new approach based on the diffusion liquid-liquid microextraction method (DLLME) along with gas chromatography-flame ionization detector (GC-FID) combined with chemometrics techniques has been developed to measure the amount of two pesticides in saffron. In this regard, in the extraction... 

Breast cancer is one of the most known types of cancer. About every eight women, one woman will suffer from one of the types of malignant tissues during her life. Diagnosing this type of cancer in the early stages is an important matter and can lead to full recovery. Therefore, one of the challenges in this field is the emergence of a fast method with high sensitivity to diagnose this disease in its early stages. Currently, biopsy is the standard method for breast cancer diagnosis. However, there are some drawbacks to this method. For instance, in order to detect the tumor margin, all breast tissue must be removed, which causes all breast tissue, including healthy tissues, to be removed.... 

Fast, non-destructive and reliable methods for food authentication purposes have been deemed important in recent years. The hyperspectral imaging technique (HSI) is a powerful method in this field, allowing the study of different features such as size, color, texture. Comprehensive interpretation is crucial, and utilizing chemometric methods enhances data interpretation. Rice is a vital and strategic food source for nearly half of the world, with Asia, particularly Iran, being a leading producer and exporter. Various types of rice fraud exist, including the mixing of high-quality and low-quality varieties, sold at a high cost. The present project aims to determine the geographical origin and... 

Regarding the importance of biological systems in daily life and the complexity of these systems, this project is concerned with this problem and especially with applications of chemometrics in proteomics. In this respect, specific importance of peptides has been taken into account in the process of construction of especial and necessary proteins for human body. Due to the risks involved in some experimental investigations, it is quite preferable to utilize modeling approaches using different sets of data. Achieving a number of specific descriptors, a powerful can be established. This model could be quiet comprehensive for the prediction of the electrophoretic mobility of peptides. This... 

The main aim of this study is developing a robust QSAR model for describing and predicting the inhibitory activities of O-(2-phthalimidoethyl)-N-substituted thiocarbamates derivatives as novel HIV-1 non-nucleoside reverse transcriptase (HIV-1 NNRTIs) inhibitors. These drugs change the active site of the reverse transcriptase enzyme, and finally halter the HIV reproduction cycle. As the first step of this study, a multiple linear regression (MLR) model was built but it has no satisfied prediction ability. As a next step, the nonlinear correlation of the molecular descriptors and activities has been investigated by using artificial neural networks (ANN). In this section the effects of variable... 

With the expansion of the pharmaceutical market and the increasing likelihood of distributing substandard medicines, it is necessary to develop methods for rapid, timely, and non-destructive analysis. These methods should enable the assessment of qualitative features such as the amount of active substance and the homogeneous distribution of materials at various stages of drug manufacturing. In this regard, numerous studies have been conducted using spectroscopy and hyperspectral imaging, particularly in the visible and near-infrared regions. The challenge here is that active ingredients in medicine and excipients look very similar in this region. They're usually white powders, and the weak... 

In this study, a new strategy based on chemometrics and extraction method of Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) combined with dispersive liquid–liquid micro-extraction (DLLME) in addition gas chromatography-flame ion detector (GC-FID) has been developed for the determination of ten pesticides in complex samples (such as tap water and milk).In this regard, experiments were designed, modeled and optimum condition was achieved by using central composite design (CCD), backward multiple linear regression (MLR) and Nelder-Mead simplex optimization. On this matter, 36 experiments for 5 extraction factors in 5 levels were generated. Also, multi-response optimization using... 

Nowadays, with increasing concerns about health of food and its influence on human health,food authenticity has become a vital issue and a major challenge for consumers and regulatory agencies. It's especially remarkable about food with high nutritional and economical value. On the other hand, solving these challenges necessitates the use of fast and reliable techniques.Among the various foods, saffron is the main candidate for food adulteration due to its low production and high economic value and from this viewpoint it's in fourth place. Since the scope of fraud in this food is vast and also Iran is the major producer of saffron in the world,the present project has highlighted the... 

In recent years, comprehensive two-dimensional gas chromatography (GC×GC) have emerged as a powerful technique suitable for the separation of complex mixtures because of their higher resolution and higher peak capacity. The invention of GC×GC is a milestone development in chromatographic history. However, one of the main challenges in chromatography and especially in GC×GC is related to the difficulty on the analysis and interpretation of the enormous amount of data obtained in these cases. In this context, resolution, identification and quantification of target compounds in the presence of interferences are issues which have a great importance and not totally solved yet. The present...