Emission cross sections for energetic O+^+(4S,2D,2P^4S,^2D,^2P)-N2_2 collisions

We report measurements of excitation functions for the O$^{+}-$N$_{2}$ process with the incident beam of $1-10$ keV O$^{+}$ in the ground O$^{+}(^{4}S)$ and metastable O$^{+}(^{2}D)$ and O$^{+}(^{2}P)$ states. The measurements are performed with the sufficiently high energy resolution of 0.001 eV, which allows to distinguish the excitation channels. The excitation cross section induced by incident ions in the metastable state O$^{+}(^{2}P)$ is much larger than that for the ground O$^{+}(^{4}S)$. The excitation cross section of N$_{2}^{+}$ ion for (0,0), (0,1) and (1,2) bands system is measured and the ratio of intensities for these bands is established as $10:3:1.$ It is shown that the cross sections for the N$^{+^{\ast }}$ions excitations in the dissociative charge exchange processes increase with the increase of the incident ion energy. The energy dependence of the excitation cross section of the band (0,0) $\lambda=391.4$ nm of the first negative system of the N$_{2}^{+}$ and degree of polarization of radiation in O$^{+}-$N$_{2}$ collision are measured for the first time. An influence of an admixture of the ion metastable state on a degree of polarization is revealed. It is demonstrated that for O$^{+}-$N$_{2}$ collision system the degree of polarization by metastable O$^{+}$($^{2}P$) ions is less compared to those that are in the ground O$^{+}$($^{4}S$) state and the sign of polarization degree of excited molecular ions does not change.Comment: 15 pages, 8 Figure

Contribution of cellular automata to the understanding of corrosion phenomena

We present a stochastic CA modelling approach of corrosion based on spatially separated electrochemical half-reactions, diffusion, acido-basic neutralization in solution and passive properties of the oxide layers. Starting from different initial conditions, a single framework allows one to describe generalised corrosion, localised corrosion, reactive and passive surfaces, including occluded corrosion phenomena as well. Spontaneous spatial separation of anodic and cathodic zones is associated with bare metal and passivated metal on the surface. This separation is also related to local acidification of the solution. This spontaneous change is associated with a much faster corrosion rate. Material morphology is closely related to corrosion kinetics, which can be used for technological applications.Comment: 13 pages, 9 figure

Experiments on the injection and containment of electron clouds in a toroidal apparatus

Injection and containment of electron clouds in azimuthally symmetric, toroidal apparatu

The dynamics of energy and charge transfer in low and hyperthermal energy ion-solid interactions

The energy and charge transfer dynamics for low and hyperthermal energy (10 eV to 2 keV) alkali and noble gas ions impacting noble metals as a function of incident energy, species and scattering geometry has been studied. The experiments were performed in an ultra-high vacuum scattering chamber attached to a low and hyperthermal energy beamline. The energy transfer was measured for K+ scattered from a Ag(001) surface along the [110] crystalline direction at a fixed laboratory angle of 90°. It was found that as the incident energy is reduced from 100 to 10 eV, the normalized scattered energy increased. Previous measurements have shown a decrease in the normalized energy as the incident ion energy is reduced due to an attractive image force. Trajectory analysis of the data using a classical scattering simulation revealed that instead of undergoing sequential binary collisions as in previous studies, the ion scatters from two surface atoms simultaneously leading to an increased normalized energy. Additionally, charge transfer measurements have been performed for Na+ scattering from Ag(001) along the [110] crystalline direction at a fixed laboratory angle of 70°. It was found that over the range of energies used (10 eV to 2 keV), the neutralization probability of the scattered ions varied from ~30% to ~70% depending on the incident velocity, consistent with resonant charge transfer. A fully quantum mechanical model that treats electrons independently accurately reproduces the observed data. Measurements of electron-hole pair excitations were used to explore the pathways which a solid uses to dissipate the energy imparted by the incident ion beam. Ultrathin film (10 nm) metal-oxide-semiconductor (Au/SiO2 /n-Si) devices were used to detect the electron-hole pairs for cases when the ion deposited all of its translational energy into the solid. The incident ions were incident at an angle normal to the surface of the device to maximize energy deposition and consequently electron-hole pair production. The rectifying metal-oxide-semiconductor device separates the electrons from the holes, allowing a current associated with electron-hole pair production to be measured. In these experiments a number of ion species (He,+ , Li+ , Ar+ , K+ ) were made incident on multiple devices and the incident energy ranged from 100 eV to 2 keV. It was found that electron-hole pair production increased with incident ion velocity consistent with a kinetic electron excitation model where the electrons in the metal are partially confined to the surface

A gp41 MPER-specific llama VHH requires a hydrophobic CDR3 for neutralization but not for antigen recognition

The membrane proximal external region (MPER) of the HIV-1 glycoprotein gp41 is targeted by the broadly neutralizing antibodies 2F5 and 4E10. To date, no immunization regimen in animals or humans has produced HIV-1 neutralizing MPER-specific antibodies. We immunized llamas with gp41-MPER proteoliposomes and selected a MPER-specific single chain antibody (VHH), 2H10, whose epitope overlaps with that of mAb 2F5. Bi-2H10, a bivalent form of 2H10, which displayed an approximately 20-fold increased affinity compared to the monovalent 2H10, neutralized various sensitive and resistant HIV-1 strains, as well as SHIV strains in TZM-bl cells. X-ray and NMR analyses combined with mutagenesis and modeling revealed that 2H10 recognizes its gp41 epitope in a helical conformation. Notably, tryptophan 100 at the tip of the long CDR3 is not required for gp41 interaction but essential for neutralization. Thus bi-2H10 is an anti-MPER antibody generated by immunization that requires hydrophobic CDR3 determinants in addition to epitope recognition for neutralization similar to the mode of neutralization employed by mAbs 2F5 and 4E10

Blocking entry of hepatitis B and D viruses to hepatocytes as a novel immunotherapy for treating chronic infections

Background. Chronic hepatitis B and D virus (HBV/HDV) infections can cause cancer. Current HBV therapy using nucleoside analogues (NAs) is life-long and reduces but does not eliminate the risk of cancer. A hallmark of chronic hepatitis B is a dysfunctional HBV-specific T-cell response. We therefore designed an immunotherapy driven by naive healthy T cells specific for the HDV antigen (HDAg) to bypass the need for HBV-specific T cells in order to prime PreS1-specific T cells and PreS1 antibodies blocking HBV entry. Methods. Ten combinations of PreS1 and/or HDAg sequences were evaluated for induction of PreS1 antibodies and HBV- and HDV-specific T cells in vitro and in vivo. Neutralization of HBV by PreS1-specific murine and rabbit antibodies was evaluated in cell culture, and rabbit anti-PreS1 were tested for neutralization of HBV in mice repopulated with human hepatocytes. Results. The best vaccine candidate induced T cells to PreS1 and HDAg, and PreS1 antibodies blocking HBV entry in vitro. Importantly, adoptive transfer of PreS1 antibodies prevented, or modulated, HBV infection after a subsequent challenge in humanized mice. Conclusions. We here describe a novel immunotherapy for chronic HBV/HDV that targets viral entry to complement NAs and coming therapies inhibiting viral maturation

Quantitative Binocular Assessment Using Infrared Video Photoscreening

Photorefraction is a technique that has been used in the past two decades for pediatric vision screening. The technique uses a digital or photographic camera to capture the examinee‟s retinal reflex from a light source that is located near the camera‟s lens. It has the advantages of being objective, binocular and low cost, which make it a good candidate for pediatric screening when compared to other methods. Although many children have been screened using this technique in the U.S., its sensitivity and other disadvantages make it unacceptable for continued use. The Adaptive Photorefraction system (APS) was developed at the Center for Laser Applications (CLA) at the University of Tennessee Space Institute (UTSI) to correct the problems in the existing PS devices. APS was designed to determine quantitatively binocular refractive errors and strabismus and to accomplish these tasks objectively, without the need of medical professionals, and it is capable of performing these objectives and reporting the digitally recorded results within one- to-two minutes. In this dissertation, two APS prototypes were constructed, and measurements were performed using both an artificial eye and human subjects. Binocular measurements of refractive error were determined, and the effects of the variation of pupil-size and gaze angle were determined. After initial corrections for ocular scattering effects, measurement of the binocular refractive error of forty human subjects was achieved, and in the myopic region with uncertainty of the method was 0.6 diopter. Ocular alignment determinations were achieved, and using a novel cover-uncover test, strabismus detection was demonstrated

Operational Evaluation Test of Mine Neutralization Systems

During the Fiscal Year 2003 Humanitarian Demining Research and Development Program Requirements Refinement Workshop, expert deminers expressed a need for a costbenefit and performance analysis for currently available deflagration (burning) and high-order (non-explosive binary mixture) mine neutralization systems, which carry fewer shipping restrictions compared with tradition explosives commonly used for mine neutralization. In response to this request, the U.S. Army Communications-Electronics Command (CECOM) Acquisition Center-Washington, D.C., published a Federal Business Opportunities (FBO) (formerly Commerce Business Daily) announcement (solicitation number W909MY-04-T0003) on 21 January 2004 on behalf of the Communications-Electronics Research, Development and Engineering Command (CERDEC), Night Vision and Electronic Sensors Directorate (NVESD), Countermine Division, Humanitarian Demining Branch, stating that the government was seeking sources for nondevelopmental, high-order or deflagration mine neutralization systems suitable for use in humanitarian demining operations. U.S. and foreign companies responded to this FBO announcement. In addition to mature, nondevelopmental systems, three developmental systems were submitted for consideration. These newer systems were deemed promising enough to be evaluated for their demining potential. A description of these devices and a summary of test findings are included in Appendix B. Of the mature, nondevelopmental systems submitted for consideration, 6 deflagration systems, which included 7 different devices, and 7 high-order systems, which included 11 different devices, were selected for further evaluation. Although the original intent had been to evaluate only non-explosive binary mixtures for high-order neutralization, two of the seven high-order systems used RDX-propelled shaped charges. A capability demonstration of these deflagration and high-order systems was conducted at a government test facility during the August to October 2004 time frame. This demonstration evaluated only hand-held systems. The results of this mine neutralization capabilities demonstration are the subject of this report

The use of activated alumina for reclaiming and reconditioning turbine, transformer and circuit breaker oils

Advancements during the past few years have provided oil manufacturers with ample reason to claim that good oils no longer wear out because of use, but that deterioration by various destructive agencies such as moisture, air, heat, oxidation, emulsification and electro-chemical action may have the effect of rendering the oil totally unfit for use --page 1

Novel Approach to Ocular Photoscreening

Photoscreening is a technique that is typically applied in mass pediatric vision screening due to advantage of its objective, binocular, and cost-effective nature. Through the retinal reflex image, ocular alignment and refractive status are evaluated. In the USA, this method has screened millions of preschool children in the past years. Nevertheless, the efficiency of the screening has been contentious. In this dissertation, the technique is reviewed and reexamined. Revisions of photoscreening technique are developed to detect and quantify strabismus, refractive errors, and high-order ocular aberrations. These new optical designs overcome traditional design deficiencies in three areas: First, a Dynamic Hirschberg Test is conducted to detect strabismus. The test begins with both eyes following a moving fixation target under binocular viewing, and during the test each eye is designed to be unconscientiously occluded which forces refixation in strabismus subjects and reveals latent strabismus. Photoscreening images taken under monocular viewing are used to calculate deviations from the expected binocular eye movement path. A significant eye movement deviation from binocular to monocular viewing indicates the presence of strabismus. Second, a novel binocular adaptive photorefraction (APR) approach is developed to characterize the retinal reflex intensity profile according to the eye\u27s refractive state. This approach calculates the retinal reflex profile by integrating the retinal reflex intensity from a coaxial and several eccentric photorefraction images. Theoretical simulations evaluate the influence from several human factors. An experimental APR device is constructed with 21 light sources to increase the spherical refraction detection range. The additional light source angular meridians detect astigmatism. The experimentally measured distribution is characterized into relevant parameters to describe the ocular refraction state. Last, the APR design is further applied to detect vision problems that suffer from high-order aberrations (e.g. cataracts, dry eye, keratoconus). A monocular prototype APR device is constructed with coaxial and eccentric light sources to acquire 13 monocular photorefraction images. Light sources projected inside and along the camera aperture improve the detection sensitivity. The acquired reflex images are then decomposed into Zernike polynomials, and the complex reflex patterns are analyzed using the Zernike coefficient magnitudes