20 research outputs found
Quantitative light element analysis: Complementary IBA methods for H to O detection using an external proton beam
No full textbcc-iron as a promising new monochromator material for thermal neutrons
No full textThe development of high-performance neutron monochromators is a long-standing and still actual topic in neutron instrumentation. Due to its high scattering cross section, iron is a particularly interesting material since it offers the possibility to obtain high reflectivities at small wavelength and good resolution. Phase transitions between bcc- and fcc-phases hindered the growth of large and high-quality single crystals in the past and only recently bcc-crystals became commercially available. We have characterized the reflecting properties of as-grown and deformed crystals using γ-rays and thermal neutrons. Absolute reflectivities well above 30% for neutron wavelengths near 1 Å could be obtained that are superior to that of all other existing monochromator materials. Hence, the progress in crystal growth along with the knowledge of directed plastic deformation makes the development of bcc-Fe neutron monochromators feasible. Their application in crystal-monochromator instruments is suitable to increase the useful neutron flux at large energies considerably
Low energy ion-solid interactions: a quantitative experimental verification of binary collision approximation simulations
No full textUltra-low energy ion implantation has become an attractive method for doping of two-dimensional materials and ultra-thin films. The new dynamic Monte Carlo program IMINTDYN based on the binary collision approximation allows a reliable prediction of low energy implantation profiles and target compositional changes, as well as efficient simulation of high energy light ion scattering. To demonstrate the quality of these predictions and simulations, we present a model case experiment where we implanted W ions into tetrahedral amorphous carbon with low (10 keV) and ultra-low (20 eV) ion energies and analyzed the W implantation profiles with high resolution Rutherford backscattering spectrometry (HR-RBS). This experiment is compared with a complete simulation of all aspects of ion-solid-interactions of the experiment using the new IMINTDYN program. A unique novel simulation option, also relevant for implantation into 2D materials, is the inclusion of the vacancy as target species with dynamic vacancy generation and annihilation. Whereas simulations neglecting vacancy formation cannot reproduce the measured implantation profiles, we find excellent agreement between simulated and measured HR-RBS spectra. We also demonstrate the important role of simultaneous weak collisions in the binary collision approximation at low projectile energies
Ion beam analysis for the detection of hydrogen and lithium using MeV ions
No full textLeichte Elemente verschließen sich den meisten Analysemethoden. Im Rahmen dieser Arbeit wurde Ionenstrahlanalyse genutzt, um wasserstoff und Lithium in Materialen nachzuwweisen.
Für den Nachweis von Wasserstoff wurde koinzidente Streuung und die resonante Kernreaktion mit N-15 genutzt um eine qantitative und qualitative Aussage treffen zu können. Für Lithium wurde die Kernreaktion zwischen Li-7 und Protonen ausgenutzt um die Zerfallsprodukte zu detektieren und aus deren Energie den Tiefenbereich zu ermitteln. Weiterhin konnte ein Aufbau entwickelt werden, welches eine Nachweisgrenze von etwa 10 ppm Lithium liefert.Light elements are not amenable to most analytical methods. In this work, ion beam analysis was used to detect hydrogen and lithium in materials.
For the detection of hydrogen, coincident scattering and the resonant nuclear reaction with N-15 were used to make a quantitative and qualitative statement. For lithium, the nuclear reaction between Li-7 and protons was used to detect the decay products and to determine the depth range from their energy. Furthermore, a setup was developed that provides a detection limit of about 10 ppm lithium.2024-07-0
Synthesis of biobased silver nano-inks for 3D printed electronics
No full textAdditive manufacturing as a method for producing electronic devices has seen significant growth in recent years, enabling simple, cost-effective, and sustainable processes. Electrohydrodynamic (EHD) printing is a promising additive manufacturing technique for producing microscale features with high precision. EHD also presents significant promise for use in microgravity, allowing for the on-demand fabrication of devices in outer-space missions. However, the selection of suitable inks remains a major challenge due to limited availability of formulations tailored for EHD processes. To address this, a new silver nano-ink platform was developed using a biobased polymer, 2-hydroxyethyl cellulose (HEC), which enables the in-situ synthesis and long-term stabilization of silver nanoparticles. This approach offers advantages over conventional polymer stabilizers, including cost, efficiency, and sustainability, while supporting high solids content and low-temperature sintering, making it well-suited for flexible electronics. The silver ink developed in this work was verified for smooth EHD printing, including in microgravity. In addition, a systematic study of nanoparticle size was conducted to understand its influence on the electrical and mechanical performance of printed films. While traditional synthesis methods rely on adjusting organic content to tune particle size, the presented platform offers tunability through a pH-mediated approach, allowing for independent control of both factors, and resulting in trends not previously reported. The results of this study were leveraged to optimize the electrical performance and mechanical durability of inks in flexible circuits, enabling robust printed features that perform reliably over 10,000s of deformation cycles. Finally, the conductive polymer PEDOT:PSS was investigated for incorporation into the ink platform to develop a high-solids silver ink that displays high conductivity without requiring any sintering step. Together, these developments offer a versatile and scalable solution for advancing sustainable, flexible, high-performance, and space-deployable electronics
Crystal Structure of an Ammonia-Permeable Aquaporin.
No full textAquaporins of the TIP subfamily (Tonoplast Intrinsic Proteins) have been suggested to facilitate permeation of water and ammonia across the vacuolar membrane of plants, allowing the vacuole to efficiently sequester ammonium ions and counteract cytosolic fluctuations of ammonia. Here, we report the structure determined at 1.18 Å resolution from twinned crystals of Arabidopsis thaliana aquaporin AtTIP2;1 and confirm water and ammonia permeability of the purified protein reconstituted in proteoliposomes as further substantiated by molecular dynamics simulations. The structure of AtTIP2;1 reveals an extended selectivity filter with the conserved arginine of the filter adopting a unique unpredicted position. The relatively wide pore and the polar nature of the selectivity filter clarify the ammonia permeability. By mutational studies, we show that the identified determinants in the extended selectivity filter region are sufficient to convert a strictly water-specific human aquaporin into an AtTIP2;1-like ammonia channel. A flexible histidine and a novel water-filled side pore are speculated to deprotonate ammonium ions, thereby possibly increasing permeation of ammonia. The molecular understanding of how aquaporins facilitate ammonia flux across membranes could potentially be used to modulate ammonia losses over the plasma membrane to the atmosphere, e.g., during photorespiration, and thereby to modify the nitrogen use efficiency of plants
Educación y salud reproductiva en la biosfera de Calakmul, Campeche. Antropología. Boletín Oficial del Instituto Nacional de Antropología e Historia: Grupos sociales y diversidad cultural. Num. 66 Nueva Época (2002) abril-junio
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"Disney is the Tiffany’s and I am the Woolworth's of the business": A critical re-analysis of the business philosophies, production values and studio practices of animator-producer Paul Houlton Terry
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Animator-producer Paul Houlton Terry has been portrayed as having little passion for the animation he produced and being more concerned with making a profit than producing entertaining cartoons with high production values. The purpose of the dissertation is to re-evaluate Terry‘s legacy to animated cartooning by analyzing his business philosophies, production values, and studio practices.
Application of four psychodynamic factors to the early life and career of Terry, 1887-1929, found that his economic decision making was characterized by: an external locus of control, risk-averse financial behaviour, extreme saving behaviour through precaution, and shrewd money management practices. Based on Terry‘s historical responses to twelve major economic, technological, or institutional forces of change for the period 1929-1955, the psychodynamic factors were found to provide accurate explanations for his studio practices and production decisions.
There was no evidence to support the conclusion that three early career disappointments undermined Terry‘s intrinsic motivation to create animated cartoons. Rather, Terry‘s lack of risk taking, external locus of control, tight studio production schedule, desire to compete with neighbour studio Fleischer, difficulty in separating financial rewards from creative processes in animation, and practice of undertaking surveillance measures on staff may have undermined his and his studio‘s creativity. Archival research found Terry to possess strong passions for and to have made significant creative contributions to the field of animation.
Biographical research found that Terry retained a stable nucleus of highly talented artists who dedicated a significant portion of their working careers to the studio. An analysis of the cel aesthetics of a random sample of animated cartoons produced during the years 1930-1955 found that Terry created animated cartoons with above average cel aesthetics when compared to the other studios thereby supporting an inference that Terry was motivated to producing quality crafted animation. Further research is suggested into the role psychodynamic factors and economic decision-making play in the film production process and a clarification of Terry‘s legacy to the field of animated cartoons
The process of adhering to aerosol therapy in adolescents with cystic fibrosis: patient and parent perspectives
No full textAdvances in medicine and healthcare have resulted in significant improvements for those children and adolescents living with a chronic health condition. However, the treatments prescribed will only work if they are taken. Rates of adherence to treatment in cystic fibrosis are low. This is especially true for adherence to aerosol therapy, a particular concern considering the reliance on aerosol therapy for the treatment of Pseudomonas aeruginosa.
The advent of Adaptive Aerosol Delivery™ (AAD) technology has enabled accurate and objective measurement of adherence to aerosol therapy treatment. However, the factors which influence the process of adhering to aerosol therapy remain largely elusive. Therefore, the current study aims to qualitatively explore the process of adhering to aerosol therapy in a clinical sample of adolescents with CF from both a patient and parent perspective. In addition, objective data downloaded from an AAD device (the I-neb™, Respironics, Chichester, UK) will be used to cue reflections on actual events around adherence.
12 participants were interviewed (six parent-child dyads). The participating adolescents were all aged between 11 and 16 years and had a CF diagnosis. There were five mothers and one father who took part. The parent and adolescent data were analysed separately using the Grounded Theory Method. Nine core categories for the parent data and nine core categories for the adolescent data were developed into a coherent framework and represented as a theoretical formulation which described the process of adhering to aerosol therapy from both a parent and adolescent patient perspective. The theoretical formulation highlights the complexity involved and details the numerous interacting biological, psychological, social and environmental influences on adherence to aerosol therapy. These findings are discussed in relation to the existing literature and clinical implications are considered. The results of the current study complement and extend previous research on adherence in CF
