G. Ali Mansoori

Asphaltene deposition: a survey of field experiences and research approaches

Abstract The paper reviews the experiences]of the oil industry and the progress and direction of the research community in their efforts to provide solutions to the asphaltene deposition problem. The oil industry, basically, seems to be combating the problem through remedial rather than preventive methods. Mechanical and chemical cleaning methods are being improvised to maintain production at economical levels. The research community, currently, is rather split in the approach to model the asphaltene deposition problem. One school of thought considers the asphaltenes dissolved in the oil in a true liquid state and dwells upon thermodynamic techniques to predict their phase behavior. Another considers asphaltenes to exist in oil in a colloidal state, as minute suspended particles, and utilizes colloidal science techniques, among other, to predict their phase behavior. Experimental work over the last 40 years suggests that asphaltenes may exist in a colloidal state in the crude oil and further pursue of the subject in this direction by both the industrial and research communities is warranted.

Utilizing the folate receptor for active targeting of cancer nanotherapeutics

The development of specialized nanoparticles for use in the detection and treatment of cancer is increasing. Methods are being proposed and tested that could target treatments more directly to cancer cells, which could lead to higher efficacy and reduced toxicity, possibly even eliminating the adverse effects of damage to the immune system and the loss of quick replicating cells. In this mini-review we focus on recent studies that employ folate nanoconjugates to target the folate receptor. Folate receptors are highly overexpressed on the surface of many tumor types. This expression can be exploited to target imaging molecules and therapeutic compounds directly to cancerous tissues.

Aggregation and deposition of heavy organics in petroleum crudes

Abstract Deposition of complex and heavy organic compounds which exist in petroleum crude can cause a number of severe problems. To prevent deposition inside the reservoir, in the well head, and inside the transmission lines it is necessary to be able to predict the onset and amount of deposition due to various factors. In the present paper the basic mechanisms of organic deposition are described based on two different microscopic theories; and their predictive capabilities are discussed. These models are the continuous thermodynamic (CT) model and the steric colloidal (SC)model. Utilization of kinetic theory of aggregation enables one to develop a fractal aggregation (FA) model which combines the ideas of the two proposed CT and SC models. The FA model is capable of describing several situations, such as the phenomena of organic deposition, growing mechanism of heavy organic aggregates, the geometrical aspects of aggregates, the size distributions of precipitated organics, and the solubility of heavy org...

Asphaltene flocculation and collapse from petroleum fluids

Deposition of complex and heavy organic compounds, which exist in petroleum crude and heavy oil, can cause a number of severe problems. To prevent deposition inside the reservoir, in the well head and inside the transmission lines, it is necessary to be able to predict the onset and amount of deposition due to various factors. In the present paper, the mechanism of asphaltene deposition, which is the major cause of most organic deposition cases, is modeled based on statistical mechanics of polydisperse polymer solutions joined with the kinetic theory of aggregation and its predictive capability is discussed. Utilization of statistical mechanics of polydisperse polymer solutions joined with kinetic theory of aggregation enables us to develop a realistic model which is able to predict both reversible and irreversible heavy organic depositions. The present model is capable of describing several reversible and irreversible situations, such as the phenomena of organic deposition, growing mechanism of heavy organic aggregates, the size distributions of precipitated organics and the solubility of heavy organics in a crude oil due to variations in oil pressure, temperature and composition. As an example, the present model is applied for heavy organics deposition prediction of two different Brazilian crude oils for which experimental data are available. It is shown that the prediction results of the present model are in good agreement with the experimental data. D 2001 Elsevier Science B.V. All rights reserved.

Measurement of property relationships of nano-structure micelles and coacervates of asphaltene in a pure solvent

We have made some progress in studies towards formation and measurement of the behavior of asphaltene micelles nano-structures that might be formed to serve as elements of nano-materials and also on synthetic strategies for creating such structures. An investigation of the micellization and coacervation measurements of asphaltenes in polar solvents at various concentrations and temperatures are made. The critical micellization concentration (CMC) and the micelle coacervation point (MCP) of nano-structure asphaltene micelles are measured using viscometry. At concentration above the CMC, asphaltene in the solution will self-associate, saturation phase will be formed and then at a higher concentration asphaltene nano-structure micelles in the solution will coacervate represented by a second sharp point of inflection corresponding to the asphaltene MCP and finally, at a higher concentration the aggregation of asphaltenes coacervates will occur. As a result of these measurements, for the first time it has become possible to produce phase diagrams for the whole range of asphaltene micellization and micelle coacervation.

A Comparative Study of Two Folate-Conjugated Gold Nanoparticles for Cancer Nanotechnology Applications

We report a comparative study of synthesis, characteristics and in vitro tests of two folate-conjugated gold nanoparticles (AuNP) differing in linkers and AuNP sizes for selective targeting of folate-receptor positive cancerous cells. The linkers chosen were 4-aminothiophenol (4Atp) and 6-mercapto-1-hexanol (MH) with nanoconjugate products named Folate-4Atp-AuNP and Folate-MH-AuNP. We report the folate-receptor tissue distribution and its endocytosis for targeted nanotechnology. Comparison of the two nanoconjugates’ syntheses and characterization is also reported, including materials and methods of synthesis, UV-visible absorption spectroscopic measurements, Fourier Transform Infra Red (FTIR) measurements, Transmission electron microscopy (TEM) images and size distributions, X-ray diffraction data, elemental analyses and chemical stability comparison. In addition to the analytical characterization of the nanoconjugates, the cell lethality was measured in HeLa (high level of folate receptor expression) and MCF-7 (low level of folate receptor expression) cells. The nanoconjugates themselves, as well as the intense pulsed light (IPL) were not harmful to cell viability. However, upon stimulation of the folate targeted nanoconjugates with the IPL, ~98% cell killing was found in HeLa cells and only ~9% in MCF-7 cells after four hours incubation with the nanoconjugate. This demonstrates that folate targeting is effective in selecting for specific cell populations. Considering the various comparisons made, we conclude that Folate-4Atp-AuNP is superior to Folate-MH-AuNP for cancer therapy.

Nanotechnology Solutions for Alzheimer's Disease: Advances in Research Tools, Diagnostic Methods and Therapeutic Agents

A century of research has passed since the discovery and definition of Alzheimers disease (AD), the primary common dementing disorder worldwide. However, AD lacks definite diagnostic approaches and effective cure at the present. Moreover, the currently available diagnostic tools are not sufficient for an early screening of AD in order to start preventive approaches. Recently the emerging field of nanotechnology has promised new techniques to solve some of the AD challenges. Nanotechnology refers to the techniques of designing and manufacturing nanosize (1-100 nm) structures through controlled positional and/or self-assembly of atoms and molecules. In this report, we present the promises that nanotechnology brings in research on the AD diagnosis and therapy. They include its potential for the better understanding of the AD root cause molecular mechanisms, ADs early diagnoses, and effective treatment. The advances in AD research offered by the atomic force microscopy, single molecule fluorescence microscopy and NanoSIMS microscopy are examined here. In addition, the recently proposed applications of nanotechnology for the early diagnosis of AD including bio-barcode assay, localized surface plasmon resonance nanosensor, quantum dot and nanomechanical cantilever arrays are analyzed. Applications of nanotechnology in AD therapy including neuroprotections against oxidative stress and anti-amyloid therapeutics, neuroregeneration and drug delivery beyond the blood brain barrier (BBB) are discussed and analyzed. All of these applications could improve the treatment approach of AD and other neurodegenerative diseases. The complete cure of AD may become feasible by a combination of nanotechnology and some other novel approaches, like stem cell technology.

Viscometric Determination of the Onset of Asphaltene Flocculation: A Novel Method

A new technique for the determination of the onset of asphaltene flocculation has been developed through accurate viscosity measurements of a crude oil being diluted with a precipitating agent (n-pentane, n-heptane, n-nonane). This detection method is based on experimental observations of an increase in the viscosity of a crude oil-asphaltene-precipitating agent suspension in which asphaltene particle aggregation occurs. The key point in this development is the phenomenon of asphaltene flocculation induced by the addition of a n-paraffin hydrocarbon (i.e. n-heptane, n-pentane, n-nonane) to crude oil. The onset of asphaltene flocculation is detected graphically, and its location is enhanced by comparison of the analyte curve with a reference system. The reference system was developed using polar and non-precipitating solvents (i.e. toluene, benzene, THF).

Nanotechnology in cancer prevention, detection and treatment: bright future lies ahead

This paper is an overview of advances and prospects in applications of nanotechnology for cancer prevention, detection and treatment. We begin with a brief description of the underlying causes of cancer. Then we address preventive treatment, disease-time treatment, and diagnosis in the context of some of the most recent advances in nanotechnology. Nanoparticle science is also briefly addressed as the foundation upon which most nanotechnology cancer therapy is based. It is demonstrated how nanotechnology can help solve one of the most challenging and longstanding problems in medicine, which is how to eliminate cancer without harming normal body tissue.

Nanostructured titanium dioxide materials: Properties, preparation and applications

Introduction Properties of Titanium Dioxide and its Nanoparticles Preparation of Nanostructured Titanium Dioxide and Titanates Applications of Nanostructured Titanium Dioxide Supported and Immobilized Titanium Dioxide Nanomaterials.