Portable Spectroscopy Crocombe, Richard A.
Applied Spectroscopy,
12/2018, Letnik:
72, Številka:
12
Book Review, Journal Article
Recenzirano
Odprti dostop
Until very recently, handheld spectrometers were the domain of major analytical and security instrument companies, with turnkey analyzers using spectroscopic techniques from X-ray fluorescence (XRF) ...for elemental analysis (metals), to Raman, mid-infrared, and near-infrared (NIR) for molecular analysis (mostly organics). However, the past few years have seen rapid changes in this landscape with the introduction of handheld laser-induced breakdown spectroscopy (LIBS), smartphone spectroscopy focusing on medical diagnostics for low-resource areas, commercial engines that a variety of companies can build up into products, hyphenated or dual technology instruments, low-cost visible-shortwave NIR instruments selling directly to the public, and, most recently, portable hyperspectral imaging instruments. Successful handheld instruments are designed to give answers to non-scientist operators; therefore, their developers have put extensive resources into reliable identification algorithms, spectroscopic libraries or databases, and qualitative and quantitative calibrations. As spectroscopic instruments become smaller and lower cost, “engines” have emerged, leading to the possibility of being incorporated in consumer devices and smart appliances, part of the Internet of Things (IOT). This review outlines the technologies used in portable spectroscopy, discusses their applications, both qualitative and quantitative, and how instrument developers and vendors have approached giving actionable answers to non-scientists. It outlines concerns on crowdsourced data, especially for heterogeneous samples, and finally looks towards the future in areas like IOT, emerging technologies for instruments, and portable hyphenated and hyperspectral instruments.
Polymeric foams are used extensively as the core of sandwich structures in automotive and aerospace industries. Normally, several experiments are necessary to obtain the required properties to model ...the response of crushable foams using finite element analysis (FEA). Hence, this research aims to develop a simple and reliable calibration process for extracting the physical parameters which are required by the material model available in the commercial FE package Abaqus. To do this, a set of experimental tests, including uniaxial compression, uniaxial tension and shear punch tests, is proposed. All the experimental tests were also simulated, and generally, good correlations between experiments and numerical models were obtained. The validity of the overall approach was finally demonstrated using an indentation test in which the foam was subjected to a more complex mixed mode loading. During these indentation tests, digital image correlation was used to observe full-field strain distribution in the foam under the indenter. Good agreement between the experimental results and the numerical predictions was found for load–displacement response, failure mode and strain distribution.
A reliable numerical damage model has been developed for adhesively bonded joints under fatigue loading that is only dependant on the adhesive system and not on joint configuration. A bi-linear ...traction–separation description of a cohesive zone model was employed to simulate progressive damage in the adhesively bonded joints. Furthermore, a strain-based fatigue damage model was integrated with the cohesive zone model to simulate the deleterious influence of the fatigue loading on the bonded joints. To obtain the damage model parameters and validate the methodology, carefully planned experimental tests on coupons cut from a bonded panel and separately manufactured single lap joints were undertaken. Various experimental techniques have been used to assess joint damage including the back-face strain technique and in situ video microscopy. It was found that the fatigue damage model was able to successfully predict the fatigue life and the evolving back-face strain and hence the evolving damage.
The aim of this research is to investigate the effect of moisture on the static response of adhesively bonded monolithic single lap joints and laminated doublers loaded in bending. All joints were ...made of aluminium alloy Al 2024-T3 bonded using epoxy film adhesive FM 73M OST. The joints were aged in deionised water at a temperature of 50°C for up to 2 years exposure. The use of different widths of specimen (5mm for monolithic single lap joints and 15mm for laminated doublers) allowed both full and partial saturation of the adhesive layer. The bulk adhesive has been characterised to obtain the coefficient of moisture diffusion, the coefficient of thermal and moisture expansion and the moisture dependent mechanical properties. The testing results showed that the mechanical properties degraded in a linear way with the moisture content. The residual strength after exposure decreased with increasing moisture content (exposure time) and tended to level off towards saturation. The damage evolution and failure of the joint has been successfully monitored using the backface strain technique and in-situ video microscopy. Progressive damage finite element modelling using a moisture dependent, bilinear traction-separation law has been undertaken to predict the residual strength. Residual stresses due to thermal and swelling strains in the adhesive layer have been included; however their effect on the predicted static strength was not significant. Good agreement was found between the predicted residual strength and the experimental result.
This paper presents a study of moisture absorption–desorption effects in single lap adhesive joints. Experiments were carried out to characterise the moisture uptake of the single part epoxide ...adhesive, FM73. Tensile testing of single lap joints manufactured from aluminium alloy 2024 T3 and O and FM73 adhesive was carried out after the joints were exposed to different conditioning environments. The experimental results revealed that the failure strength of the single lap joints with 2024 T3 adherends progressively degraded with time when conditioned at 50
°C, immersed in water. However, the joint strength almost completely recovered after moisture was desorbed. The single lap joints with 2024 O adherends showed decreased strength for 28 days of conditioning, after which strength recovered, reaching a plateau after 56 days. Again, strength almost completely recovered on desorption of moisture. The strength recovery of the joints, after desorption of moisture, showed that the degradation of the adhesive was largely reversible. Analysis of the failure surfaces revealed that the dry joints failed cohesively in the adhesive layer and that the failure path moved towards the interface after conditioning. The failure mode then reverted back to cohesive failure after moisture desorption.
The recognised relationship between oral health and general health, the rapidly increasing older population worldwide, and changes in the type of oral health care older people require have raised ...concerns for policymakers and health professionals. Nurses play a leading role in holistic and interprofessional care that supports health and ageing. It is essential to understand their preparation for providing oral health care.
To synthesise the evidence on nursing students' attitudes towards, and knowledge of, oral healthcare, with a view to determining whether oral health education should be incorporated in nursing education.
: Three electronic databases - PubMed, Scopus, and CINAHL.
Original studies addressing the research objective, written in English, published between 2008 and 2019, including students and educators in undergraduate nursing programs as participants, and conducted in Organisation of Economic Co-operation and Development countries.
Data extracted from identified studies were thematically analysed, and quality assessment was done using the Mixed Methods Appraisal Tool.
From a pool of 567 articles, 11 met the eligibility criteria. Findings documented five important themes: 1.) nursing students' limited oral health knowledge; 2.) their varying attitudes towards providing oral health care; 3.) the need for further oral health education in nursing curricula; 4.) available learning resources to promote oral health; and 5.) the value of an interprofessional education approach to promote oral health care in nursing programs.
The identified studies recruited small samples, used self-report questionnaires and were conducted primarily in the United States.
The adoption of an interprofessional education approach with a focus on providing effective oral health care, particularly for older people, needs to be integrated into regular nursing education, and practice. This may increase the interest and skills of nursing students in providing oral health care. However, more rigorous studies are required to confirm this. Nursing graduates skilled in providing oral health care and interprofessional practice have the potential to improve the oral and general health of older people.
This paper is concerned with modelling damage and fracture in woven fabric CFRP single-lap bolted joints that fail by net-tension. The approach is based on the assumption that damage (matrix ...cracking, delamination and fibre tow fracture) initiates and propagates from the hole in a self-similar fashion. A traction–separation law (based on physically meaningful material parameters) is implemented within an Extended Finite Element Method (XFEM) framework and used to predict the joint strength. Reasonable agreement between model and experiment was obtained for test configurations covering different weave types and lay-ups, a range of joint geometries (two hole diameters and a range of normalised joint widths) and finger-tight and fully torqued clamp-up conditions. The greatest discrepancies were for situations where the tensile fracture mechanisms were more complex, and hence not captured fully in the model or when bearing failure occurred.
Abstract Osseointegrated trans-femoral implant is a relatively new orthopaedic anchoring method for connecting a stump with a prosthesis. Through a follow-up study of a patient over six years, ...significant bone remodelling has been observed. Finite element (FE) simulations were carried out to investigate the relationship between the bone remodelling and the strain re-distribution around the trans-femoral osseointegrated implant system. An initial FE model representing the original status of the femur-implant assembly was created from CT scans of the subject prior to osseointegration. Follow-up X-ray images were acquired at various stages post-surgery, which allowed the changes in bone wall thickness to be measured. By updating the bone thickness in the initial model, a series of follow-up FE models were created. Representative load associated with the subject׳s body weight was applied to the models, and the strain re-distributions were calculated. The results showed that in order to minimise the adverse effect of bone remodelling, an osseointegration implant made by functionally gradient materials are preferred over homogeneous materials.
The post-World War II availability of commercial spectrometers spurred the development of professional spectroscopic societies: The Infrared and Raman Discussion Group in the UK, the Coblentz ...Society, and the Society for Applied Spectroscopy in the USA. There was a desire to ensure that customers understood the instrumentation and techniques, became part of a community, and had access to the latest subject matter knowledge. With the advent of low-cost routine instruments, and portable instruments in the field, professional societies have a distinct role to play in education and training, especially as libraries deaccession (withdraw) even comparatively recent books on practical spectroscopy.
This work is concerned with investigating the residual static strength of adhesively bonded joints after long-term exposure to a combined mechanical-hygro-thermal environment. Associated experimental ...data are also reported. The degradation process of the joints was modelled using a fully-coupled approach, with the moisture concentration affecting the stress distribution and the stress state affecting the moisture diffusion analyses simultaneously. A bilinear cohesive zone model was then used to implement the progressive damage FE analysis of the quasi-statically loaded joints following the ageing phase. This model is degraded using the damage factors (creep strain and moisture uptake) accumulated over the ageing process and calibrated against the experimental results from static tests on the bulk adhesive. Predicted and experimentally-measured quasi-static responses for the aged adhesive joints were found to be in good agreement.
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