SEM characterization of silicon nanostructures: can we meet the challenge?

The current semiconductor technology road map for device scaling champions a 4.5 nm gate length in production by 2022. The scanning electron microscope (SEM) as applied to critical dimensions (CD) metrology and associated characterization modes such as electron beam-induced current and cathodoluminescence (CL) has proved to be a workhorse for the semiconductor industry during the microelectronics era. We review some of the challenges facing these techniques in light of the silicon nanotechnology road map. We present some new results using voltage contrast imaging and CL spectroscopy of top-down fabricated silicon nanopillar/nanowires (<100 nm diameter), which highlight the visualization challenge. However, both techniques offer the promise of providing process characterization on the 10-20 nm scale with existing technology. Visualization at the 1 nm scale with these techniques may have to wait for aberration-corrected SEM to become more widely available. Basic secondary electron imaging and CD applications may be separately addressed by the He-ion microscope.     

Ludwik Finkelstein and measurement – A challenge for the future

A brief reflection on the contribution of Ludwik Finkelstein and, echoing his own words, the continually changing and developing response to the push of advancing technology and the pull of changing requirements, setting a challenge for education in the field of measurement and instrumentation for future generations.     

The 25th anniversary of BUA for the assessment of osteoporosis: time for a new paradigm?

The measurement of broadband ultrasonic attenuation (BUA) in cancellous bone at the calcaneus for the assessment of osteoporosis was first described within this journal 25 years ago. It was recognized in 2006 by Universities UK as being one of the '100 discoveries and developments in UK Universities that have changed the world' over the past 50 years. In 2008, the UK's Department of Health also recognized BUA assessment of osteoporosis in a publication highlighting 11 projects that have contributed to '60 years of NHS research benefiting patients'. The BUA technique has been extensively clinically validated and is utilized worldwide, with at least seven commercial systems currently providing calcaneal BUA measurement. However, there is still no fundamental understanding of the dependence of BUA upon the material and structural properties of cancellous bone. This review aims to provide an 'engineering in medicine' perspective and proposes a new paradigm based upon phase cancellation due to variation in propagation transit time across the receive transducer face to explain the non-linear relationship between BUA and bone volume fraction in cancellous bone.     

Markers for the lymphatic endothelium: In search of the holy grail?

The ability to discriminate reliably at the histological level between blood and lymphatic microcapillaries would greatly assist the study of a number of biological and pathological questions and may also be of clinical utility. A structure-function comparison of these types of microcapillary suggests that differences which could function as markers to allow discrimination between blood and lymphatic endothelium should exist. Indeed, to date a variety of such markers have been proposed, including basement membrane components, constituents of junctional complexes such as desmoplakin and enzymes such as 5'-nucleotidase. Additionally, a variety of cell surface molecules are thought to be differentially expressed, including PAL-E, VEGFR-3, podoplanin, and LYVE-1. Several of the lymphatic markers proposed in the literature require further characterization to demonstrate fully their lymphatic specificity and some have proven not to be reliable. The relative merits and drawbacks of each of the proposed markers is discussed.     

Assessing the quality of inspection for tapered aircraft fastener holes using an engineer’s blue contact test

Tapered interference-fit fasteners (e.g. Taper-lok) are commonly used by the aerospace industry due to their high fatigue strength. The inspection relies on a ‘true’ geometry gauge coated with a thin film of engineer’s blue being brought firmly into contact with the tapered hole. The pattern created on the gauge is then used to identify bearing surface area and distribution. This research investigates if the inspection reflects the hole geometry, and under what conditions the inspection may be assumed valid. The results show that the shade of the blue on the gauge as inspected through computer vision correlates with the unloaded geometry evaluated via a roundness tester, in particular when the red channel is taken alone. The inspection method falls short of accurately representing small features, particularly those tangential to the gauge removal direction. Thresholding visually or by computer vision may reasonably be used to identify the contact region pattern, however factors limiting blue migration mean the contact area may appear smaller than it actually is.     

First-generation teeth in nonmammalian lineages: Evidence for a conserved ancestral character?

The present study focuses on the main characteristics of first-generation teeth (i.e., the first teeth of the dentition to develop in a given position and to become functional) in representatives of the major lineages of nonmammalian vertebrates (chondrichthyans, actinopterygians, and sarcopterygians: dipnoans, urodeles, squamates, and crocodiles). Comparative investigations on the LM and TEM level reveal the existence of two major types of first-generation teeth. One type (generalized Type 1) is characterized by its small size, conical shape, atubular dentine, and small pulp cavity without capillaries and blood vessels. This type is found in actinopterygians, dipnoans, and urodeles and coincides with the occurrence of short embryonic periods in these species. The other type assembles a variety of first-generation teeth, which have in common that they represent miniature versions of adult teeth. They are generally larger than the first type, have more complex shapes, tubular dentine, and a large pulp cavity containing blood vessels. These teeth are found in chondrichtyans, squamates, and crocodiles, taxa which all share an extended embryonic period. The presence in certain taxa of a particular type of first-generation teeth is neither linked to their phylogenetic relationships nor to adult body size or tooth structure, but relates to the duration of embryonic development. Given that the plesiomorphic state in vertebrates is a short embryonic development, we consider the generalized Type 1 first-generation tooth to represent an ancestral character for gnathostomes. We hypothesize that an extended embryonic development leads to the suppression of tooth generations in the development of dentition. These may still be present in the form of rudimentary germs in the embryonic period. In our view, this generalized Type 1 first-generation teeth has been conserved through evolution because it represents a very economic and efficient way of building small and simple teeth adapted to larval life. The highly adapted adult dentition characteristic for each lineage has been possible only through polyphyodonty.     

Developing a bio-mechanotronic probing system for estimating soft tissue Young’s modulus in vivo

In many medical applications such as rehabilitation, clinical palpation, and manipulation of organs, it is important to characterize soft-tissue properties accurately. This paper presents a bio-mechatronic probing system that could be used for estimating soft tissue Young’s modulus in vivo. The system employs an electromagnetic spatial displacement sensor. The accuracy and reliability of the system were investigated. In addition, the effect of indentation rate on the variation of the values of the measured effective Young’s modulus was also studied. A series of elastomers with different Young’s modulus (ranged from 13.08 to 36.19 kPa) were assessed with both the probing system and a Hounsfield material testing machine. Intra-individual and inter-individual variations of the system were tested by five independent operators. The probing system was applied to assess the effective Young’s modulus of human body parts in vivo. Fifteen healthy female subjects with age of 22.5 ± 4.3 years old were included for the in vivo test. The system was shown to be highly accurate (R ² = 0.995) in comparison with the results obtained by the mechanical testing machine and had good reliability (intra-individual variation = 5.43%, inter-individual variation = 5.99%). The average effective Young’s modules of the region of umbilicus were 13.33 and 10.71 kPa for two different sites, respectively. Based on the results obtained, it is believed that this probing system was an accurate and reliable tool for rapidly assessing the mechanical properties of human body tissues in vivo.     

Computer-supported workplace for the production manager — a tool for preparing strategic decisions

This paper describes how the production manager can make better decisions more quickly than before through a new computer-supported information architecture. Therefore, the position of the production manager in the enterprise is first described. The information supply situation is then represented and evaluated before the initial stages of solving partial problems are examined. The architecture for a computer-supported information system for production managers is then presented.     

Walking aids for elderly people: a systematic overview

Reduction of falls of elderly people has been an active research area for many years.Falls of older people can be signicantly reduced through the smart use of technologies.Such technologies can help older people to regain mobility and reduce their reliance on community care services.Therefore,mobility aids,as one of the main components of these assistive technologies,are mainly discussed in this paper.Recent obstacle detection systems and mobility aids will be reviewed in this paper,where different features are explicitly addressed.     

Crosslinking-mediated activation of the FcεRI: Does it need antigen for success?

Mast cells (MCs), hematopoietic cells of the myeloid lineage, are well-known for their pro-inflammatory nature contributing to the development of various allergic and autoimmune diseases. One of the characteristic receptors on MCs, the high-affinity receptor for IgE (FcεRI), is activated in its IgE-bound state via binding and crosslinking by polyvalent antigen. This results in its phosphorylation by the SRC family kinase LYN, initiating differential signaling pathways, eventually triggering immunological effector functions, such as degranulation and cytokine production. Few publications have reported on FcεRI-dependent but antigen-independent MC activation by antibody-mediated crosslinking of membrane molecules (e.g., transmembrane proteins and glycosphingolipids) that are both localized in membrane rafts and in close vicinity to the FcεRI. In this Viewpoint we will briefly introduce FcεRI-mediated MC stimulation, cite examples of FcεRI-proximal molecules, the crosslinking of which can cause FcεRI-dependent MC activation, and discuss the potential of certain viruses as well as auto-antibodies to act as indirect FcεRI-crosslinking agents. In latter cases, antigen-independent FcεRI-mediated pro-inflammatory MC activation could contribute to the development of detrimental cytokine storms.     

Does a monochromator improve the precision in quantitative HRTEM?

This paper addresses the question as to what extent the incorporation of a monochromator in an electron microscope can enhance the performance of high resolution transmission electron microscopy (HRTEM). The monochromator will reduce the chromatic aberration, and hence the information limit, at the expense of beam current, leading to a decrease in signal intensity and a corresponding decrease in signal-to-noise ratio (SNR). Both aspects, information limit and SNR, have been included in a quantitative evaluation based on the statistical precision with which the position of an atom column can be estimated. It is shown that the effect of a monochromator on the attainable precision depends on the microscope and monochromator parameters, as well as on the characteristics of the object.     

An immunofluorescence method for postembedded tissue in the acrylic resin Technovit 9100 New® using fluorescein isothiocyanate secondary detection

Immunofluorescence labeling on postembedded tissue in resin is a formidable task. Although resin components and stabilizers are a source of additional strong native fluorescence that overlaps with absorption and emission spectra of commonly used green fluorophores, the unfixed tissue is also subject to native fluorescence. For tissue embedded in resin, we hypothesized that initially removing the resin and subsequently quenching the native fluorescence from the sample could result in specific immunofluorescence signals. The hypothesis was tested on fixed tissue samples embedded in Technovit 9100 New®. Deacrylated and rehydrated semithin sections from a variety of soft tissues were exposed to a quenching solution prior to immunolabeling. Cryostat sections from snap frozen tissue were also stained to assess whether all antigens investigated in fixed tissue were adequately detected. The secondary detection included antibodies conjugated with fluorescein isothiocyanate. The results were evaluated using conventional dark-field and confocal laser scanning microscopy. Both forms of microscopy confirmed the considerable lowering of the native fluorescence associated with the resin and fixed tissue samples with enhanced specific signal. The cryostat tissue sections using the same antibodies in equivalent concentrations confirmed labeling of the same cellular sites as those observed in the fixed tissue. This article describes a method for immunofluorescence labeling in Technovit 9100 New resin embedded tissue and suggests the likely chromogenic elements generating autofluorescence. Microsc. Res. Tech., 2009. © 2009 Wiley-Liss, Inc.     

Vibroacoustic: The challenges of a mission impossible?

Why it is difficult to solve a vibroacoustic problem; what are the hidden pitfalls that one is called to overcome; are there methods or techniques suggested in other fields of physics that can help to formulate an efficient vibroacoustic prediction model? The authors provide personal answers to these questions and suggest also a classification of the numerous prediction methods proposed in the literature.     

Application of the Shack–Hartmann Wavefront Sensor for Monitoring the Parameters of a Supersonic Gas Jet

Results of an experimental study of the density distribution in a small-size (1–2 mm in diameter) supersonic gas jet in vacuum are reported. The measurements are performed by the developed Shack–Hartmann wavefront sensor, which consists of a microlens array with 100 × 100 elements and a video camera with a resolution of 2048 × 2048 pixels. The reliability of measurements in terms of the space and time resolution, as well as in terms of the minimum levels of phase changes induced by the tested object, is analyzed.     

Development of a Setup for the Discrimination of β+ and γ Rays

Abstract

A β⁺–γ discrimination set‐up was developed and applied to the ²²Na radioisotope. The radioisotope emits positrons (β⁺) and these positrons create γ rays by annihilating with electrons. These annihilation γ rays were used here, and the discrimination between these positrons and γ rays was investigated by the coincidence measurement between time signals and the energy signals. The detection system presented here uses a 3 inch (diameter) by 3 inch (length) NaI(Tl) inorganic scintillation detector for γ detection and 3 inch (diameter) by 3 inch (length) plastic scintillation detector for β⁺ detection.     

Magnetic mitohormesis: A non-invasive therapy for inflammatory disorders?

An organism’s survival depends on its ability to adapt to stress. Mitochondria are the cellular integrators ofenvironmental stressors that ultimately translate their responses at the organismal level, and are thus central to theprocess whereby organisms adapt to their respective environments. Mitochondria produce molecular energy viaoxidative phosphorylation that then allows cells to biosynthetically respond and adapt to changes in theirenvironment. Reactive oxygen species (ROS) are by-products of oxidative phosphorylation that can be eitherbeneficial or damaging, depending on the context; ROS are hence both the conveyors of environmental stress as wellas cellular “adaptogens”. Mitohormesis refers to the process whereby low levels of oxidative stress spur survivaladaptations, whereas excessive levels stymie survival. Low energy and frequency pulsing electromagnetic fields havebeen recently shown capable of stimulating mitochondrial respiration and ROS production and instillingmitohormetic survival adaptations, similarly to, yet independently of, exercise, opening avenues for the futuredevelopment of Magnetic Mitohormetic interventions for the improvement of human health. This viewpoint exploresthe possibilities and nuances of magnetic-based therapies as a form of clinical intervention to non-invasively activatemagnetic mitohormesis for the management of chronic diseases.