Glancing angle deposition of sculptured thin metal films at room temperature.

Metallic thin films consisting of separated nanostructures are fabricated by evaporative glancing angle deposition at room temperature. The columnar microstructure of the Ti and Cr columns is investigated by high resolution transmission electron microscopy and selective area electron diffraction. The morphology of the sculptured metallic films is studied by scanning electron microscopy. It is found that tilted Ti and Cr columns grow with a single crystalline morphology, while upright Cr columns are polycrystalline. Further, the influence of continuous substrate rotation on the shaping of Al, Ti, Cr and Mo nanostructures is studied with view to surface diffusion and the shadowing effect. It is observed that sculptured metallic thin films deposited without substrate rotation grow faster compared to those grown with continuous substrate rotation. A theoretical model is provided to describe this effect.

Mechanical characteristics of silicon nanostructures using force distance spectroscopy.

Experimental studies were undertaken to determine mechanical stiffness of Si chevron nanostructures grown by glancing angle deposition. Atomic force microscope based force-distance spectroscopy was performed on two types of chevron structures. The average stiffness of four-armed chevrons was found to be 381 +/- 16 Nm(-1), while that of five-armed chevrons was determined to be 375 +/- 23 Nm(-1). Simulations using finite element modeling were carried out to understand the mechanical characteristics of chevrons. For the nanostructures investigated in the present study, the simulation results indicate that while five-armed chevrons behave as springs, the four-armed chevrons act as cantilevers. It is shown that the position of loading point, physical dimensions and the geometry of the chevron control the overall mechanical response of chevron structures when subjected to an external load. It is proposed that by controlling the deposition parameters in glancing angle deposition, the topography of the structures and hence the position of loading points can be manipulated to generate a desirable mechanical response.

Highly ordered nanopatterns on Ge and Si surfaces by ion beam sputtering.

The bombardment of surfaces with low-energy ion beams leads to material erosion and can be accompanied by changes in the topography. Under certain conditions this surface erosion can result in well-ordered nanostructures. Here an overview of the pattern formation on Si and Ge surfaces under low-energy ion beam erosion at room temperature will be given. In particular, the formation of ripple and dot patterns, and the influence of different process parameters on their formation, ordering, shape and type will be discussed. Furthermore, the internal ion beam parameters inherent to broad beam ion sources are considered as an additional degree of freedom for controlling the pattern formation process. In this context: (i) formation of ripples at near-normal ion incidence, (ii) formation of dots at oblique ion incidence without sample rotation, (iii) transition between patterns, (iv) formation of ripples with different orientations and (v) long range ordered dot patterns will be presented and discussed.

Phase change thin films for non-volatile memory applications.

The rapid development of Internet of Things devices requires real time processing of a huge amount of digital data, creating a new demand for computing technology. Phase change memory technology based on chalcogenide phase change materials meets many requirements of the emerging memory applications since it is fast, scalable and non-volatile. In addition, phase change memory offers multilevel data storage and can be applied both in neuro-inspired and all-photonic in-memory computing. Furthermore, phase change alloys represent an outstanding class of functional materials having a tremendous variety of industrially relevant characteristics and exceptional material properties. Many efforts have been devoted to understanding these properties with the particular aim to design universal memory. This paper reviews materials science aspects of chalcogenide-based phase change thin films relevant for non-volatile memory applications. Particular emphasis is put on local structure, control of disorder and its impact on material properties, order-disorder transitions and interfacial transformations.

Ion mass and energy selective hyperthermal ion-beam assisted deposition setup.

For the synthesis of high-quality thin films, ion-beam assisted deposition (IBAD) is a frequently used technique providing precise control over several substantial film properties. IBAD typically relies on the use of a broad-beam ion source. Such ion sources suffer from the limitation that they deliver a blend of ions with different ion masses, each of them possessing a certain distribution of kinetic energy. In this paper, a compact experimental setup is presented that enables the separate control of ion mass and ion kinetic energy in the region of hyperthermal energies (few 1 eV - few 100 eV). This ion energy region is of increasing interest not only for ion-assisted film growth but also for the wide field of preparative mass spectrometry. The setup consists of a constricted glow-discharge plasma beam source and a tailor-made, compact quadrupole system equipped with entry and exit ion optics. It is demonstrated that the separation of monoatomic and polyatomic nitrogen ions (N+ and N2+) is accomplished. For both ion species, the kinetic energy is shown to be selectable in the region of hyperthermal energies. At the sample position, ion current densities are found to be in the order of 1 µA/cm2 and the full width at half maximum of the ion beam profile is in the order of 10 mm. Thus, the requirements for homogeneous deposition processes in sufficiently short periods of time are fulfilled. Finally, employing the described setup, for the first time in practice epitaxial GaN films were deposited. This opens up the opportunity to fundamentally study the influence of the simultaneous irradiation with hyperthermal ions on the thin film growth in IBAD processes and to increase the flexibility of the technique.

Investigation on plasma immersion ion implantation treated medical implants.

In this work the biocompatibility of osteosynsthesis plates treated with plasma immersion ion implantation (PIII) was tested using a rat model. Small rods (Ø 0.9 mm, and length 10 mm) prepared from different materials-pure Ti, anodised Ti, and two NiTi alloys (SE 508, and SM 495)-were implanted with oxygen by PIII to form a rutile surface layer and subsequently inserted into rat femurs, together with a control group of untreated samples. The results of the biomechanical tests correlate with the histological results, and show that plasma immersion ion implantation leads to an increase of biocompatibility and osseointegration of titanium and NiTi, albeit no improvement of the (bad) biocompatibility of the anodised Ti. Despite the layer thickness of up to 0.5 microm a strong influence of the base material is still present.

Marital status, fatness and obesity.

Marital status is related to morbidity and mortality, with married people healthier and at lower risk of death than those who are unmarried (especially among men). However, the relationship between marital status and obesity is not well established. Role theory suggests through a marital causation model that people in the marital role are more likely to be obese, and through a marital selection model that people in the marital role are less likely to be obese because of stigmatization. The martial causation model was examined using data from the National Survey of Personal Health Practices and Consequences, a cross-sectional national telephone survey of 3025 adults age 20-64 in the United States. Sequential regression analyses revealed that married men were significantly fatter and more likely to be obese than never married or previously married men, even when demographic, social, and physical variables were controlled. By contrast, marital status was not significantly associated with fatness or obesity among women when other variables were controlled. The marital role appears to influence fatness and obesity among men, but not women.

[Plasma immersion ion implantation. A new method for homogeneous surface modification of complex forms of medical implants]. / Plasma-Immersions-Ionenimplantation. Ein neues Verfahren zur homogenen Oberflächenmodifizierung komplex geformter medizinischer Implantate.

Plasma immersion ion implantation (PIII) is a new method for the inexpensive rapid modification of the near-surface region of medical implants of complex shapes. PIII combines the advantages of conventional plasma and ion beam technologies. This article describes the physical basis of the procedure and the construction of a PIII system, and presents typical PIII parameters. In a number of examples, the use of the PIII to modify the surface of biocompatible materials (chrome-nickel stainless steel, titanium, titanium-aluminium-vanadium alloy) with the aim of reducing wear, increasing biocompatibility or improving adhesion, is described. Finally, the possibilities of combining PIII with other technologies are considered.

Nanoscale-resolved elasticity: contact mechanics for quantitative contact resonance atomic force microscopy.

Contact resonance atomic force microscopy (CR-AFM) constitutes a powerful approach for nanometer-resolved mechanical characterization of surfaces. Yet, absolute accuracy is frequently impaired by ad hoc assumptions on the dynamic AFM cantilever characteristics as well as contact model. Within the present study, we clarify the detailed interplay of stress fields and geometries for full quantitative understanding, employing combined experimental numerical studies for real AFM probes. Concerning contact description, a two-parameter ansatz is utilized that takes tip geometries and their corresponding indentation moduli into account. Parameter sets obtained upon experimental data fitting for different tip blunting states, are discussed in terms of model-specific artificiality versus real contact physics at the nanoscale. Unveiling the underlying physics in detail, these findings pave the way for accurate characterization of nanomechanical properties with highest resolution.

Integration of a broad beam ion source with a high-temperature x-ray diffraction vacuum chamber.

Here, the integration of a low energy, linearly variable ion beam current density, mechanically in situ adjustable broad beam ion source with a high-temperature x-ray diffraction (XRD) vacuum chamber is reported. This allows in situ XRD investigation of phase formation and evolution processes induced by low energy ion implantation. Special care has been taken to an independent adjustment of the ion beam for geometrical directing towards the substrate, a 15 mm small ion source exit aperture to avoid a secondary sputter process of the chamber walls, linearly variable ion current density by using a pulse length modulation (PLM) for the accelerating voltages without changing the ion beam density profile, nearly homogeneous ion beam distribution over the x-ray footprint, together with easily replaceable Kapton(®) windows for x-rays entry and exit. By combining a position sensitive x-ray detector with this PLM-modulated ion beam, a fast and efficient time resolved investigation of low energy implantation processes is obtained in a compact experimental setup.

The influence of change in marital status on weight change over one year.

Marital status is an influence on body weight. Changes in marital status and body weight were examined in the National Survey of Personal Health Practices and Consequences, a telephone survey of 2,436 adults interviewed twice approximately 1 year apart. Two statistical methods for analyzing weight change were compared, and both produced similar results: regression analysis of weight change and regression analysis of weight at follow-up controlling for baseline weight. The findings revealed that women who entered marriage had greater weight change than women who remained married. Analysis of weight gain and weight loss separately showed that women who became married lost less weight than those who remained married. For men, there were no statistically significant relationships between marital change and weight change over a 1-year period. These findings support other literature showing that marital status plays a role in body weight changes. The results suggest gender differences may exist in the rate of body weight change after marriage, with more immediate changes in women than men.

Questionnaire-based measures are valid for the identification of rural households with hunger and food insecurity.

This study assessed the validity of questionnaire-based measures for the identification of rural households with hunger and food insecurity. Data used were from a 1993 survey of 193 households with women and children living at home in a rural county. Two interviews provided data on demographics, factors contributing to food insecurity, coping strategies, fruit and vegetable consumption, disordered eating behaviors, height, weight, dietary recall and household food-stores inventory. This information was used to develop a definitive criterion measure for hunger and food insecurity to compare with hunger and food insecurity items from Radimer/Cornell, the Community Childhood Hunger Identification Project (CCHIP) and the Third National Health and Nutrition Examination Survey (NHANES III). The Radimer/Cornell and CCHIP questionnaire-based measures had good specificity (i.e., percentage of truly food secure correctly classified; 63-71%) and excellent sensitivity (i.e., percentage of truly food insecure correctly classified; 84-89%) when compared with the criterion measure. Estimates of the prevalence of household food insecurity from the criterion, Radimer/Cornell and CCHIP measures were almost identical. The overall agreement of the Radimer/Cornell and CCHIP measures was very good. These measures can be validly used to screen for hunger and food insecurity among rural households similar to those studied and to target subpopulations for food programs. The NHANES III item alone had excellent specificity but poor sensitivity, and underestimated prevalence.

Characteristics related to elderly persons' not eating for 1 or more days: implications for meal programs.

We examined how social, economic, location, health, and food need characteristics are related to elderly persons' not eating for 1 or more days. The following variables were positively related to not eating: ethnicity, location, receipt of Medicaid, living alone, health problems, mobility, age less than 80 years, cancer, nausea, difficulty swallowing, diarrhea, loss of appetite, and receipt of food from a food pantry. These results have implications for allocating meal program funds, screening clients, and monitoring whether clients eat regularly.

Dependency on soup kitchens in urban areas of New York State.

We studied the dependency of persons on soup kitchens in Albany, Buffalo, Rochester, Syracuse, and Westchester County, New York. Seventeen percent of the meal recipients were homeless, 62 percent lived in apartments or houses, 20 percent were working, 40 percent were women, and 17 percent had a child in their household. Fifty-nine percent started eating at the soup kitchen more than a year ago, and 51 percent ate five or more meals at soup kitchens in the last week. Most reported they came to the soup kitchen because of economic problems or lack of food; 93 percent had incomes below the poverty threshold. Most used some government food program; 48 percent received food stamps. Utilization of soup kitchens and other programs differed between men and women and between households with and without children.