Effect Of Atomic Number Research Articles

Electron scattering on atomic hydrogen and hydrogenoid atoms in their metastable state (2S-2S) in the relativistic regime

We present, in the relativistic regime, the results of the study of elastic scattering of hydrogen atoms in its metastable state (2S-2S) by electron impact in the absence of a laser field. In the first calculation, semi-relativistic wave functions present hydrogen states. Dirac spinor describes the incident and scattered electrons. The condition Zα<<1 of using Darwin wave functions has been verified. The second approach uses the exact relativistic calculation of this process. The relativistic case calculations converge to those of the non-relativistic case within the low electron velocity range. In the high incoming energy range, the Coulomb effect and exchange effect are neglected. We present the relativistic differential cross-section RDCS as a function of the final scattering angle for different energies of the incident electron. The effect of atomic number Z for hydrogenoid atoms on the cross-section is examined.

Sample thickness affects contrast and measured shape in TEM images and in electron tomograms

We investigated the effect of nanoparticle (NP) image broadening and its contrast change dependence on a support matrix thickness in a transmission electron microscope (TEM). We measured the effect of NP size and atomic number on its image broadening. Based on the experimental TEM images we generated tomograms of NPs on four types of support matrix. The measured shape aspect ratio of the NPs in such tomograms depends on the geometry of the support matrix. For example, the aspect ratio of 6 nm NP placed on a thin film with window-frame support is 1.14, while the aspect ratio of 6 nm NP on a rod-shaped support with 910 nm diameter is 1.67 in a tomogram.

Effect of atomic number and pressure on plasma pinch properties and characteristic soft x-ray emission in PF1000

In this study, the Lee code is used to compute the characteristics soft x-ray yield (Ysxr) production for nitrogen (N2), oxygen (O2), neon (Ne), and argon (Ar) and bremsstrahlung radiation for hydrogen (H2), deuterium (D2), and helium (He) with pressure variation in PF1000 of 2.5–2.6 MA for D2. In the calculation of characteristic soft x-ray, the corresponding temperature windows of the said gases are set into the code at which they are ionized to their H-like and He-like levels. The focus pinch parameters such as radius ratio (minimum radius of plasma pinch column/anode radius), ion density, specific heat ratio, pinch energy density, self-absorption correction factor, and maximum induced voltage are computed at the optimum pressure of each gas. The obtained pinch plasma temperature range (1.2–2.2) × 106 K of H2, D2, and He is sufficiently high for fully ionized plasmas and the resulting bremsstrahlung radiation (14 J) for He is significantly larger than for H2 (0.26 J) and D2 (0.62 J). The optimum Ysxr of Ne(∼9314 J) at 0.51 Torr with pinch energy density (PED) (∼26 × 108 Jm−3) is found to be the highest whilst for Ar(∼7 J) at 0.019 Torr with (∼1.2 × 108 Jm−3) is the lowest. It is found that the radius ratio (∼0.05) of Ne is 3-fold smaller than that (∼0.16) in Ar. This enhancement of compression in pinch of Ne increases the ion density significantly by a factor of 253 than in Ar gas. Thus, the results show a strong correlation of plasma pinch properties with Ysxr for various gases.

Late effects of heavy-ion space radiation on splenocyte subpopulations and NK cytotoxic function

Introduction: With current goals of increased space exploration and travel to Mars, there has been great interest in understanding the long-term effects of high atomic number, high energy (HZE) ion exposure on various organ systems and the immune system. Little is known about late effects on the immune system after HZE exposure. Therefore, our objective was to determine how natural killer (NK) cell populations were affected in geriatric mice that were exposed to HZE particles during middle-age, thereby representing elderly retired astronauts that undertook deep space missions.Methods: 10 month old male CBA/CaJ mice were whole-body irradiated: sham (control); 150-cGy gamma-rays (delivered in 1 fraction); 40-cGy 1-GeV/nu 28Si14+ ions (delivered in 3 fractions); 40-cGy 1-GeV/nu 16O8+ ions (1 fraction); and 40-cGy 1-GeV/nu 16O8+ ions (3 fractions). The mice were sacrificed 1–1.5 yr post-exposure, and the spleens harvested. Splenocyte effector (E) cells were harvested and added to 51Cr-labeled Yac-1 target (T) cells in E:T ratios of 12:1, 25:1, 50:1, and 100:1. NK cytotoxicity was measured with 51Cr release. In addition, 2 million splenocytes were aliquoted and stained with a seven-antibody cocktail, and flow cytometry was used to determine the percentage of NK, B lymphocytes, and T lymphocytes in the splenocyte population.Results: Mice exposed to either a single fraction of 150-cGy gamma rays or 40-cGy 16O8+ ions in 3 fractions were found to have significant decreases in NK cytotoxicity of approximately 30% and 25%, respectively. No significant differences were observed in NK cytotoxicity for 40-cGy 16O8+ ions delivered in 1 fraction, or 40-cGy 28Si14+ ions delivered in 3 fractions. No significant differences were observed in the percentage of spleen cells that were NK (%NK) amongst the groups.Conclusion: Fractionated HZE ion exposure has the potential to affect the innate arm of the immune system long after exposure, leading to decreases in NK cell function. Therefore, protective countermeasures may need to be considered to decrease the risk of reduced long-term immune function in elderly retired astronauts that undertook deep space missions.

Effect of Atomic Number on Plasma Pinch Properties and Radiative Emissions

The aim of the research is to examine the dependence of plasma pinch properties and radiation emissions on the atomic number of the operating gas within the dense plasma focus device (NX2) when using hydrogen and argon gases. Simulation was performed with Lee’s code on an NX2 dense plasma focus at a constant gas pressure value ( P 0 = 0.5 torr ). The results showed that the minimum radius of the plasma focus in the case of the hydrogen plasma pinch was 0.30 cm and in the case of the argon plasma pinch 0.17 cm, and this affected the value of the radiation emission as it was 7.8 × 10 − 6 J and 11 J for the hydrogen and argon pinch, respectively. The energy of the ion beam released by the breakdown of the plasma pinch was found as E n = 23.8 J in the state of hydrogen and E n = 105 J in the state of argon.

Effect of high Z materials loading in the performance of polystyrene-based thin-film plastic scintillators

The paper describes the effect of high effective atomic number (Zeff) materials loading in polystyrene based thin-film Plastic Scintillators (PS). Thin plastic scintillator sheets have been loaded with high Z materials such as BaFBr:Eu, Gd2O2S:Tb, Gd2O3, BaF2, CeO2 and Bi2O3. Polystyrene based PS sheets of 250 ± 50 μm thickness have been prepared by dissolving predetermined quantities of polystyrene, 2,5-Diphenyloxazole (PPO) and 1,4-bis(5-phenyl-2-oxazolyl) benzene (POPOP) in the p-xylene solvent. High Zeff material powders of 23μm size are mixed in the plastic scintillator solution and coated over the cellulose acetate-based transparency sheets. The dried films are peeled off, and their photoluminescence, radioluminescence, pulse height spectrum and response to alpha, beta, gamma and neutron radiations are studied by adopting suitable methods. The high Zeff materials for loading in PS are selected based on their physical properties like refractive index, bandgap, Zeff, Photoluminescence (PL) properties. While the composite scintillator loaded with 14.3 wt% of BaFBr:Eu2+ showed significant increase compare to other high Z materials. The loading concentration has been optimized as 14.3 wt% from the BaFBr:Eu2+ studies. Most of the composite scintillators showed improvement in radioluminescence and pulse height spectra for different radiations.

Plasmonic gold nanoagents for cancer imaging and therapy

AbstractGold nanoparticles (AuNPs) are a popular material in the field of nanoscience because of their excellent biocompatibility and unique physical and chemical properties, and have been widely used in the biomedical field. AuNPs have a simple preparation method, controllable shape and size, high electron density and atomic number, superparamagnetic properties, and radiation sensitization effect, and their optical absorbance can be adjusted to the required biological window; thus, AuNPs are suitable for cancer imaging (photoacoustic imaging, computed tomography, and magnetic resonance imaging), photothermal therapy, and radiotherapy. AuNPs can also be used as carriers to load photosensitizers or chemotherapeutic agents, and therefore, can also be used in photodynamic therapy and chemotherapy. In summary, AuNPs and their assemblies can simultaneously realize cancer diagnosis and treatment, providing a new idea in the development of precision medical treatment.

Effect of Mean Atomic Number of Measured Object on Measurement Results of X-Ray Computed Tomography (CT) for Dimensional Measurements

Effect of Mean Atomic Number of Measured Object on Measurement Results of X-Ray Computed Tomography (CT) for Dimensional Measurements

Molecular dynamics factors affecting on the structure, phase transition of Al bulk

In this work, we study the effect of atomic number (N) at temperature (T), T = 300 K; effect of T to Al5324 bulk; effect of annealing time (t) to Al5324 bulk at crystallization temperature (Tg), effect of Tg = 600 K on structure, phase transition of Al bulk by Molecular Dynamics (MD) method with embedded Sutton-Chen (SC) potential and recirculating boundary conditions. The results were analyzed through Radial Distribution Function (RDF), total energy of the system (Etot), size (l), Common Neighborhood Analysis (CNA) method, crystallization temperature (Tg) (via relationship between Etot, T). The obtained results show that the size (l) of Al bulk is always proportional with atomic number (N) according to the formula l ∼ N−1/3 and the total energy of the system (Etot) always proportional to the number of atoms (N) according to the formula Etot ∼ N−1. In particular, Al bulk always exists in three types of structures, including: Face Centred Cubic (FCC), Hexagonal Close-Packed (HCP), and Amorphous (Amor) structure. When atomic number (N) is increased, the temperature (T) decreases and the tempering time (t) increases then the number units of FCC, HCP increases, Amor decreases leads to change structure and phase transition of Al bulk.

Calculation the Effect of Atomic Number for Projectile and Target on the Electronic Stopping Power

In this research, a theoretical study was made to calculate electronic stopping power for heavy charged particles (Protons, Alpha particles, Heavy ions (C,O)) which interact with atomic targets (H,C,O,Si) by using the equation which resulting from distant and close collisions ,as it has been calculating the effect of atomic number (Z1) for projectiles and the effect of atomic number (Z2) for targets on the electronic stopping power in range velocities (v=vo,2vo,5vo,10vo). &#x0D; Mathematical approximative methods are used in the calculation and some of the equation programmed by Matlab language to obtain the theoretical result which is shown in the graphic.

Problem of the Account of Matrix Effect in Electron Probe Microanalysis of Rock-Forming Minerals

Four methods of correction and three methods of calculation of absorption coefficients are tested in electron probe microanalysis of rock-forming minerals. Experimental data by Pouchou and Pichoir, Sewell–Love–Scott, and Armstrong are attracted in tests. It is shown that the correction factor can be calculated with the error no more than 1 rel. % if a short-wave line (matrix effect is determined mainly by the effect of atomic number) is used as an analytical line or the analytical line belongs to the absorption K-edge of elements present in the sample. In the presence of binary matrix effect, when the analytical line absorbs in the K–L1 region, the situation is more complex and additional studies are required.

Some Factors Affected on Structure, Mechanical of Ni Bulk

The article examines the effect of atomic number, temperature and tempering time on microstructure and mechanical of Ni bulk by molecular dynamics simulation and deformation z-axis. Samples Ni with N = 4000, 5324, 6912, and 8788 atoms at 300 K, 6912 atoms at T = 1100, 900, 700, 500, 300 K and 6912 atoms at 900 K after different annealing time. The samples were incubated with the same heating rate . Combined with common neighborhood analysis method shown in sample is always existing four types structure: FCC, HCP, BCC, and Amor. In particular, structural units FCC, HCP and Amor always prevail and BCC are very small and appear only at 300, 500 K with 6912 atoms. When increasing atomic number, lowering temperature or increasing tempering time will facilitate crystallization process leading to increased FCC and HCP units number. The increasing FCC, HCP units number and additional appearance BCC structure led to change microstructure and mechanical of material: When increasing atom, lowering temperature and increasing incubation time lead to an increase in density of atoms that increase mechanical properties of the material.

Some Factors Affecting Structure, Transition Phase and Crystallized of CuNi Nanoparticles

This paper studies the influence of atomic number at temperature of 300 K, temperature at 5324 atoms, phase transition & crystallization at different temperatures of 300 K, 500 K, 600 K, 700 K, 1100 K after 2×10 5 move steps number by increasing temperature of 4×10 12 K/s on microstructure, phase transition temperature, phase transition & crystallization of CuNi nanoparticle by molecular dynamics (MD) with embedded interaction Sutton-Chen and soft boundary conditions. Microstructure characteristics are analyzed through radial distribution function (RDF), energy, size, phase transition temperature (via relationship between energy and temperature), phase transition & crystallization (via radial distribution function, E tot , move step number and common neighbor analysis (CNA)). Results show that first peak position of the radial distribution function is dominant; lengths of Cu-Cu, Ni-Ni with the results of Ni-Ni consistent with simulation. At 300 K temperature, nanoparticle appears in four phases namely FCC, HCP, ICO and Amorphous, presenting the effect of atomic number, temperature and move step number on microstructure, phase transition temperature and phase transition & crystallization of CuNi nanoparticle.

RETRACTED: Thermodynamic Stability of ABX Heavy Elements of TaIrGe, TiIrSb, TaIrSn and ZrIrSb TCOs Using the Half-Heusler Technique

Electronic structure theory has recently been used to propose hypothetical compounds in presumed crystal structures, seeking new useful functional materials. The functional materials include transparent conductors needed in solar cell, light emitting diode and flat panel displays, which represent the usually contraindicated functionalities of optical transparency (generally associated with electrical insulators) coexisting with electrical conductivity (generally associated with optically opaque metals). Usually, such hypothetical materials are meta-stable, albeit with technologically useful long lifetimes. Yet, in other cases, suggested hypothetical compounds may be significantly higher in energy than their lowest-energy crystal structures or competing phases, making their synthesis and eventual device-stability questionable. Shifting focus from the previous searches of doping wide-gap metal oxides turns our focus to the newly predicted never before synthesized ABX compounds of TiIrSb, TaIrSn and ZrIrSb called “filled tetrahedral structure” (sometimes called Half-Heusler). We give interest to these compounds because; there stability range is located around X-richest and A/B-poor growth. The ‘inverse design’ principles are applied to ABX compounds. Then the effect of atomic number in their materials to tolerance of sufficient level of off-stoichiometry in creation of free holes that avoid the ionic sites and thus lead to high hole mobility at room temperature.

Effect of atomic number and atomic weight on time-dependent inelastic deformation in metals

Effect of atomic number and atomic weight on time-dependent inelastic deformation in metals

The biological effects induced by high-charged and energy particles and its application in cancer therapy

The radiobiological effects of high atomic number and energy (HZE par cles) ion beams are of interest for radioprotec on in space and tumor radiotherapy. Space radia on mainly consists of heavy charged par cles from protons to iron ions, which is dis nct from common terrestrial forms of radia on. HZE par cles pose a significant cancer risk to astronauts on prolonged space missions. With high delivered energies and intense ioniza on, HZE par cles can damage not only the biological systems but also the shielding materials. HZE par cles are more effec ve than low-LET radia on like γor X-rays to induce gene c muta on and cancer. On Earth, similar ions are being used for targeted cancer therapy due to the advantage of the inverse dose profile, with delivering higher doses to the tumor while keeping lower doses to the surrounding ssues. In this review, we focus on the recent insights into the biological effects caused by HZE par cles and the corresponding mechanism. We also discuss the current applica on of HZE par cle in cancer therapy. Understanding the mechanisms underlying the repair of DNA damage induced by HZE par cles contribute to accurately es mate the risks to human health associated with HZE par cle exposure and to improve the effec veness of tumor radiotherapy.

Physico-chemical studies for strontium sulfate radiation dosimeter

Anhydrous strontium sulfate (SrSO4) has shown a promise candidate as a dosimeter for low dose applications producing unique EPR signals with γ-rays which it has a linear response relationship (r2 = 0.999) in the range of 1–100 Gy. The present study extended to evaluate the properties of strontium sulfate dosimeter in intermediate dose range of technology applications. It was observed that the intensity of the EPR signal at g = 2.01081 increases with a 3rd polynomial function in the range of 0.10–15 kGy. In addition, the radical (SO4−) provides a stable signal with a good reproducibility (0.107%). Other physics characteristic including the collision of mass stopping power dependence of the system and the effect of atomic number in different energy regions were investigated. The uncertainty budget for high doses has obtained from the measurement with value of 3.57% at 2σ confidence level.

Experimental Evaluation of Free Radical Generation in Nanoparticle-Aided HDR Brachytherapy

Effect of high atomic number (Z) nanoparticles such as gold and platinum in radiation therapy has extensively been characterized in terms of enhancement in dose deposition owing to an increase in the probability of photoelectric interaction and subsequent increase in secondary electron generation. Recent studies demonstrating higher effective cell kill than estimated cell kill based on physical dose deposition due to radiation in the presence of gold nanoparticles point toward some additional biochemical effects.

A facile route for CdSe nanoparticles: synthesis and structural characterisation

Semiconducting CdSe nanoparticles of a few nanometers in size were synthesised by solvothermal decomposition of novel, single-source molecular precursor Cd(II) complex of bis(aminoethyl)selenide ((NH2CH2CH2)2Se.CdCl2)) using quinoline as coordinating agent at 200°C. Particle size, structural phase, elemental compositions, morphology and optical bandgap of as-synthesised nanoparticles were characterised using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDAX), transmission electron microscopy (TEM) and UV–Vis spectroscopy. The XRD pattern revealed that hexagonal CdSe nanocrystallites of ≈7 nm average size can be obtained by the solvothermal decomposition of ((NH2CH2CH2)2Se.CdCl2)) in quinoline. Elemental composition ratio of Cd:Se reveals non-stochiometric phase as confirmed standard less ZAF quantification, where Z, A and F are the matrix correction parameters, describing the atomic number effect (stopping power and backscatter effect), the absorption effect, and the fluorescence effect, respectively, in EDAX. Absorption spectra show blue shift in the absorption in nano particles with respect to their bulk counterpart and the calculated optical bandgap is estimated at 3·94 eV. This method has several advantages such as non-toxic and non-pyroforic single-source precursor, relatively low temperature and avoids the need for inert environment. However, quinoline used as coordinating agent has proved ineffective in capping and dispersing the nanoparticles and need to be further investigated.

Study of Ion Beam Processing Using Different Materials

Study of Ion Beam Processing Using Different Materials Simulation of ion beam processing in different target materials using different noble gases was studied. The Simulation was conducted using singly charged neon, argon and krypton ions at different energies greater than 3keV and up to 10keV. The open source computer code SRIM 3D was used in the simulation to determine the ion beam penetrability into the target material, as well as the range dependence on the beam’s energy. The effect of target material atomic number on the ion penetration range was studied. The distribution of the range and the trajectory of the ions in the target material were determined. The sputtering yield of the studied target materials due to ion bombardement was determined showing that the highest sputtering yield is when krypton is used as the working gas for the production of the ions, however, the least range is that of the krypton ion beam.