Radioactively driven colloids: A special case of anomalous diffusion

Citation: Wilson, G., Bahadori, A. A., & Bindra, H. (2019). Radioactively driven colloids: A special case of anomalous diffusion. Journal of Applied Physics, 126(12), 124308. https://doi.org/10.1063/1.5116220A novel concept of self-propelled, radioactively driven colloids is introduced. The focus of this paper is on assessing the impact of alpha emissions on colloidal kinematics. Using Langevin dynamics and a random walk model, a theory has been developed to describe this motion. This theory shows a special case of anomalous diffusion. Numerical simulations have substantiated the theory. It is shown that alpha-particle emission can significantly affect the motion of colloidal particles, although a very short-lived radioisotope is required

Cancer registry in Iran: A brief overview

Cancer registry is an important tool for any successful cancer control program. The first formal cancer related data from Iran were published in 1956. In 1969, observations documenting a high incidence of esophageal cancer in the Caspian Littoral, urged researchers to set up the first population-based cancer registry in this region. This cancer registry was established jointly by University of Tehran and the International Agency for Research on Cancer (IARC). In 1976, another cancer registry started its activities in Fars Province. In 1984, the Parliament passed a bill mandating the report of all tissues "diagnosed or suspected as cancer tissue" to the Ministry of Health. While only 18% of all estimated cancer cases were reported in first reports, this rate increased to 81% in 2005 In 1998, Tehran Population-Based Cancer Registry started to collect data from cases of cancer referred to the treatment and diagnostic facilities throughout the Tehran metropolis. Digestive Disease Research Center, Tehran University of Medical Sciences, established four new population-based cancer registries in Northern Iran and another in Kerman Province in the south. These five provinces have a total population of about 9.5 million, and constitute about 16% of the total population of Iran. While the pathology-based cancer registration is in place, we hope that the addition of the population-based cancer registries, and establishment of new registries in poorly-covered areas, will improve cancer reporting in the country

Anisotropy in Sand–Fibre Composites and Undrained Stress–Strain Implications

Among the plethora of studies on anisotropy in fibre-reinforced sands, there exist conflicting views on effects on the steady-state deformations of initial packing. These conflicting views are further confused by strictly limited experimental evidence on flow in complex loading environments where the principal stresses rotate whereby shearing and torsional stresses combine, and when extension in soil relieves the compressive stresses. In the heuristic of intrinsically anisotropic nature of the soil and in recognition of the inability of placement methods to overcome such anisotropy, this paper aims to use the orientation of principal stress and soil initial packing state combined as proxy parameters to further the knowledge of plastic behaviour in fibre-reinforced sands. This study furthers the knowledge of the dependency of steady states on anisotropy in composite geomaterials. In doing so, the direction of principal stress orientation is varied from 15° to 60° (from vertical axis), taking an intermediate principal stress ratio of 0.5 and 1.0 and two initial confining pressures. Twenty-four undrained torsional shear tests are conducted using a hollow cylindrical torsional shear apparatus. Under compression and plain strain conditions, torsional stresses limit the improvements in soils’ undrained shear strength upon fibre reinforcement. Extension in soil remarkably increases fibres’ contribution to betterment of undrained strength. Fibres are least effective under low isotropic confining pressures and also for certain ranges of torsional stresses

Liquefaction resistance of fibre-reinforced silty sands under cyclic loading

Whether the so-called double porosity in soils with a loose and natural packing state is a concept with real-world implications is a fundamental yet controversial question in the study of cyclic undrained shear behaviour of fibre-reinforced silty sands. An attempt is made here to clarify the question by means of particle-level modelling combined with 41 undrained cyclic triaxial shear tests. The study shows that the initial Random Loose Packing changes to Random Close Packing and then Close Packing with silt content increments. The transition from random to close packing occurs at a threshold silt content which is relatively lower in coarser sands. For sands with 40% silt content. Irrespective of fine content, fibres tend to sit deep into the silt pellets and encrust the macro-pore spaces. Generally, increasing fibre content leads to an increase in the average number of contacts per particle, dilation and easier dissipation of excess pore water pressure, a decrease in contact forces and improved liquefaction resistance. For sands with >40% silt content, effectiveness of fibre reinforcement diminishes with increasing sand median size

EVALUATION OF NON H. PYLORI SPIRAL ORGANISMS IN HUMAN GASTRIC BIOPSIES BY USING PCR AND MICROSCOPIC METHODS IN IRAN (FIRST REPORT)

Introduction and Objectives: The Discovery of Helicobacter pylori in 1982 increased interest in the range of other spiral bacteria that had been seen in Stomach (Marshall & Warren 1984).The power of technologies such as the polymerase chain reaction (PCR) with genus specific primers revealed that many of these bacteria belong to the genus Helicobacter. These nonpylori helicobacters are increasingly being found in human clinical specimens. Non-pylori Helicobacters are Gram-negative, motile, long, tightly coiled, Spiral bacteria ,with three to eight coils, that cause of some gastric problems like gastritis, peptic ulceration and Mcosa-Associated Lymphoid Tissue (MALT) lynphoma in animals and humans. Materials and Methods: Samples taken during endoscopy were analyzed by rapid urease test, PCR and light microscope(Giemsa and Gram staining). In this study 270 samples were collected from Patients with gastric disorders. Presence of Helicobacters confirmed by a positive urease test and Helicobacter genus specific PCR method utilized. DNA was prepared from biopsies using the Qiamp tissue kit (QIAGEN Inc., Valencia, Calif.) and frozen at −20°C (like gastric samples/biopsies). DNA samples that PCR positive were amplified with 16SrRNA gene primers against Helicobacter species. Results: In gastric biopsy specimen's non-pylori helicobacter spp., have been observed. At the end of the study we found that 71% of urease tests, 0.37% of light microscopic studies (we observed some spiral gram negative bacteria with 2-7 coils) and 0.74% of PCR tests were positive. In analysis with PCR route 2 person (both of them were Male) were infected with H.heilmanniilike organisms( one of them kept a dog for 5 years as a pet).16S rRNA gene amplification was performed on 270 DNA samples and results were positive for H.heilmannii in two cases (275-bp), but negative for H.bizzozeronnii,H.felis and H. Salmonis

Comparison of Passive and Active Exploration Flight Test 1 Radiation Detector Measurements with Trapped Proton and Vehicle Shielding Model Calculations

Citation: Stoffle N, Gaza R, Nounu H, Lee K, and Bahadori A 2016 Comparison of Passive and Active Exploration Flight Test 1 Radiation Detector Measurements with Trapped Proton and Vehicle Shielding Model Calculations NASA/TP-2016-218599 NASA Johnson Space Center: Houston, TX http://ston.jsc.nasa.gov/collections/TRS/415.refer.htmlThe Battery-operated Independent Radiation Detector and Radiation Area Monitors ?own on-board the Exploration Flight Test 1 mission provide a unique opportunity to compare vehicle modeling results with both active and passive radiation measurements. The environment de?nitions and modeling e?orts are described, and a comparison of passive and active measurements is presented with respect to the modeling results

Hydrogen production by photoreforming of organic compounds

Productivity with respect to direct water photosplitting. Methanol is used here as model molecule to investigate the effect of catalyst composition and of substrate concentration on photocatalytic activity. Simple catalysts formulations were selected, in order to propose an easily scalable technology with a poorly expensive material. TiO2 with different structure (anatase, rutile and a mixture of them) was used as semiconductor, doped with a small amount of Au (0.1 wt%) to improve the lifetime of photogenerated charges. A new photoreactor was set up, with external irradiation that improves the scale up feasibility and possible future application with solar energy. Methanol conversion and hydrogen productivity increased with increasing methanol concentration up to 15 wt%. Rutile led to the highest conversion, but TiO2 P25 showed the highest hydrogen productivity. The best result was achieved by treating a 15 wt% methanol solution with 0.1 wt%Au/TiO2 P25, which led to 0.276 mol H2 h-1 kgcat-1

Modeling a 3-D multiscale blood-flow and heat-transfer framework for realistic vascular systems

Modeling of biological domains and simulation of biophysical processes occurring in them can help inform medical procedures. However, when considering complex domains such as large regions of the human body, the complexities of blood vessel branching and variation of blood vessel dimensions present a major modeling challenge. Here, we present a Voxelized Multi-Physics Simulation (VoM-PhyS) framework to simulate coupled heat transfer and fluid flow using a multi-scale voxel mesh on a biological domain obtained. In this framework, flow in larger blood vessels is modeled using the Hagen–Poiseuille equation for a one-dimensional flow coupled with a three-dimensional two-compartment porous media model for capillary circulation in tissue. The Dirac distribution function is used as Sphere of Influence (SoI) parameter to couple the one-dimensional and three-dimensional flow. This blood flow system is coupled with a heat transfer solver to provide a complete thermo-physiological simulation. The framework is demonstrated on a frog tongue and further analysis is conducted to study the effect of convective heat exchange between blood vessels and tissue, and the effect of SoI on simulation results.publishedVersio

research article

During embryonic development and tissue homeostasis, reproducible proportions of differentiated cell types are specified from populations of multipotent precursor cells. Molecular mechanisms that enable both robust cell-type proportioning despite variable initial conditions in the precursor cells, and the re-establishment of these proportions upon perturbations in a developing tissue remain to be characterized. Here, we report that the differentiation of robust proportions of epiblast-like and primitive endoderm-like cells in mouse embryonic stem cell cultures emerges at the population level through cell-cell communication via a short-range fibroblast growth factor 4 (FGF4) signal. We characterize the molecular and dynamical properties of the communication mechanism and show how it controls both robust cell-type proportioning from a wide range of experimentally controlled initial conditions, as well as the autonomous re-establishment of these proportions following the isolation of one cell type. The generation and maintenance of reproducible proportions of discrete cell types is a new function for FGF signaling that might operate in a range of developing tissues