Laser shock processing (LSP) is increasingly applied as an effective technology for improving the properties of different metallic components. This is done principally to enhance their corrosion and ...fatigue life behaviour, stress corrosion cracking resistance, etc. In this paper, LSP has been applied to a commercially pure Mg and a Mg-1Zn alloy (wt%) which is aimed to be used as a biodegradable material for biomedical applications. The rational for microalloying with Zn is not only influencing the bacterial response, but also enhancing corrosion resistance and mechanical strength of Mg without causing any toxic effect. The present work is focussed on the examination of the effects of the LSP treatment on the relevant surface related properties of the samples and their correlation with the surface and subsurface induced modifications such as residual stress state, microstructural, roughness, hardness, etc. Central to this investigation is the study of the corrosion response and antibacterial properties against Staphylococcus epidermidis of the different samples as a function of material and LSP parameters. The results show that the application of LSP introduces compressive residual stresses up to 1 mm deep. This occurs together with a significant improvement in corrosion resistance, and less bacterial colonization.
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•LSP treatment was successfully applied to extruded pure Mg and Mg1Zn alloy.•Maximum compressive residual stresses, in the range of 20%–25% of their yield strengths, have been achieved by moderate overlapping densities treatments.•Zinc-containing material is more corrosion resistant than pure Mg and the higher EOD promotes higher corrosion resistance at 24 h of immersion in DPBS.•LSP treatment enhances the resistance against bacteria adhesion of alloy and pure magnesium, and is slightly correlated with the density of pulses applied.
The aim of this paper is to investigate the evolution of a matrix-filler interface during the processing of novel composites formed by a matrix of polylactic acid (PLA) and Mg particles, when they ...are manufactured by Materials Extrusion. The particles addition to the PLA was carried out through the preparation of a Magnesium stable suspension in the polymer solution. To improve the Mg dispersion, the surfaces of the particles were previously modified by the adsorption of dispersants, namely Polyethylenimine (PEI) and Cetyltrimethylammonium bromide (CTAB) in aqueous suspension. The physical and mechanical characterization of PLA/Mg composites show that the Mg surface modification is the key to its successful dispersion due to the formation of ionic interactions between the dispersants and the matrix. This is favoured by the seeding effect of the PEI-modified Mg particles over the PLA re-precipitation during the composite shaping. Moreover, a PEI-PLA covalent bond appeared in the printed scaffolds as a consequence of the temperature applied (165 °C) during extrusion and printing. Consequently, the matrix-filler strengthened interface improved the extrusion process and permits the printing of 3D customized pieces. At the same time, particle agglomeration and the nozzle blocking is prevented.
Trypanosoma cruzi, the agent of Chagas disease, can be subdivided into six discrete typing units (DTUs), TcI, TcIIa, TcIIb, TcIIc, TcIId or TcIIe, each having distinct epidemiologically important ...features. Dozens of genetic markers are available to determine the DTU to which a T. cruzi isolate belongs, but there is no consensus on which should be used. We selected five assays: three polymerase chain reaction (PCR)-restriction fragment length polymorphisms based on single nucleotide polymorphisms (SNPs) in the HSP60, Histone H1, and GPI loci, and PCR product size polymorphism of the LSU rDNA and mini-exon loci. Each assay was tested for its capacity to differentiate between DTUs using a panel of 48 genetically diverse T. cruzi clones. Some markers allowed unequivocal identification of individual DTUs, however, only by using a combination of multiple markers could all six DTUs be resolved. Based upon the results we recommend a triple-assay comprising the LSU rDNA, HSP60 and GPI markers for reliable, rapid, low-cost DTU assignment.
Using the method of maximal cuts, we construct the complete D-dimensional integrand of the five-loop four-point amplitude of N=4 super-Yang-Mills theory, including nonplanar contributions. In the ...critical dimension where this amplitude becomes ultraviolet divergent, we present a compact explicit expression for the nonvanishing ultraviolet divergence in terms of three vacuum integrals. This construction provides a crucial step towards obtaining the corresponding amplitude of N=8 supergravity required to resolve the general ultraviolet behavior of supergravity theories.
Soiling by dry deposition affects the power output of photovoltaic (PV) modules, especially under dry and arid conditions that favor natural atmospheric aerosols (wind-blown dust). In this paper, we ...report on measurements of the soiling effect on the energy yield of grid-connected crystalline silicon PV modules deployed in five cities across a north-south transect of approximately 1300 km in the Atacama Desert ranging from latitude 18°S to latitude 30°S. Energy losses were assessed by comparing side-by-side outputs of four co-planar PV modules. Two of the PV modules of the array were kept clean as a control, while we allowed the other two to naturally accumulate soiling for 12 months (from January 2017 to January 2018). We found that the combination of high deposition rates and infrequent rainfalls led to annual energy losses that peaked at 39% in the northern coastal part of the desert. In contrast, annual energy losses of 3% or less were measured at relatively high-altitude sites and also at locations in the southern part of the desert. For comparison, soiling-induced annual energy losses of about 7% were measured in Santiago, Chile (33°S), a major city with higher rainfall frequency but where urban pollution plays a significant role.
Over the last years new evidences of several short-lived regional maxima of the geomagnetic field intensity at various times and locations have been defined. These features have important ...implications both for geomagnetic field modeling and for Earth's dynamo simulations. However, the nature, extent and underlying causes of these variations are still poorly understood. The major constraint for an adequate description of these important features is the absence of continuous detailed records and the current limited availability of precisely dated geomagnetic field recorders. In this context, archeological materials from superimposed strata covering long sequences of occupation provide a powerful tool to investigate the temporal variability of geomagnetic field strength at decadal and centennial time scales. In this work we report the archeomagnetic study of 79 potteries from Southeastern Spain collected in 14 different stratigraphic units. The chronological framework of the studied collection, ranging from the 9th to the 12th centuries, is based on historical/archeological data such as written sources and well-established typological and archeometric documentation on ceramics found on reference contexts in the area. Additionally, two radiocarbon dates obtained from two different stratigraphic units confirm the proposed chronological intervals. From classical Thellier and Thellier experiments including partial thermoremanent magnetization (pTRM) checks and TRM anisotropy and cooling rate corrections, height new high-quality mean intensities were derived. The new data provide an improved description of the sharp abrupt intensity decay that took place in Western Europe after the 800 AD intensity maximum, the most significant geomagnetic field intensity feature observed in Europe over the last two millennia. The new results confirm that several rapid intensity changes (with rates higher than 10 μT/century) took place in Western Europe during the recent history of the Earth. The comparison between the regional curve of Western Europe and the SHA.DIF.14k global field model predictions suggests that the 800 AD event observed in Europe is probably controlled by non-dipolar geomagnetic sources.
•Height new high-quality archeointensities were obtained for Spain.•Several short-lived regional intensity maxima are confirmed for the last 2000 yrs.•Intensity rates larger than 10 μT/century are observed.•Available data and models suggest that the 800 AD event may have a predominantly non-dipolar character.
Context.
Low-resolution spectroscopy is a frequently used technique. Aperture prism spectroscopy in particular is an important tool for large-scale survey observations. The ongoing ESA space mission
...Gaia
is the currently most relevant example.
Aims.
In this work we analyse the fundamental limitations of the calibration of low-resolution spectrophotometric observations and introduce a calibration method that avoids simplifying assumptions on the smearing effects of the line spread functions.
Methods.
To this aim, we developed a functional analytic mathematical formulation of the problem of spectrophotometric calibration. In this formulation, the calibration process can be described as a linear mapping between two suitably constructed Hilbert spaces, independently of the resolution of the spectrophotometric instrument.
Results.
The presented calibration method can provide a formally unusual but precise calibration of low-resolution spectrophotometry with non-negligible widths of line spread functions. We used the
Gaia
spectrophotometric instruments to demonstrate that the calibration method of this work can potentially provide a significantly better calibration than methods neglecting the smearing effects of the line spread functions.
Purpose
To compare the optical quality between two intraocular lenses (IOLs): the Mini WELL Ready progressive multifocal (SIFI Medtech, Catania, Italy), and the TECNIS Symfony (Abbott Laboratories, ...Illinois, USA), which both provide a continuous range of vision from far to near positions.
Methods
The in vitro optical quality of each lens was assessed with an instrument conceived for measuring the modulation transfer function (MTF). The optical quality of each lens was described in terms of MTF, through-focus MTF, defocus tolerance, pupil dependence, and Strehl ratio MTF. These metrics were assessed for the best lens far focus, and at four vergences (from −1.5 to −3.0 D in 0.5-D steps), at 3.0 and 4.5 mm apertures.
Results
The through-focus curves of each lens showed two main areas: one corresponding to far-distance vision, and another to intermediate- and near-distance vision. Both lenses showed similar MTF curves and Strehl ratio values at both apertures. The optical quality of both lenses slightly decreased with the aperture for all vergences. Nevertheless, the quality of the progressive multifocal lens increased with the aperture at far-distance vision. This lens also showed the largest defocus tolerance at near-distance vision for both apertures.
Conclusions
The results obtained in the present study suggest that both designs might enlarge the depth of focus. Whereas, the Mini WELL Ready showed better optical quality than the TECNIS Symfony at far vision with 4.5 mm aperture, and larger defocus tolerance than the diffractive lens at near-distance vision.
Summary
Background
Patients with advanced or metastatic skin cancer have a limited life expectancy and the majority die as a result of the tumor despite modern treatment options. The preferences of ...these patients concerning care during their last phase of life are currently unknown.
Patients and methods
150 patients with advanced skin cancer (AJCC/UICC stage III or IV) were interviewed using a structured questionnaire.
Results
75% of the respondents wished to die in their domestic environment, although a more advanced tumor stage and increased reflection upon end‐of‐life care lead away from this wish. However, only 42% reported having communicated this wish to someone else. 55% of the respondents had completed advance directives, while younger patients did this significantly less often (95% CI: 0.11–0.56; p = 0.001). The majority of patients (62%) would like to have discussions about possibilities for end‐of‐life care with the attending dermato‐oncologist.
Conclusions
Although the moment of death is unpredictable, early initiation of end‐of‐life advance care planning appears prudent. The attending dermato‐oncologists should take the initiative to raise the subject with their patients during routine control visits. In this context, it may be useful to present available care options to patients and relatives and to design strategies for the event of deteriorating health.
Aberrations and accommodation Del águila-carrasco, Antonio J; Kruger, Philip B; Lara, Francisco ...
Clinical and experimental optometry,
January 2020, Letnik:
103, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Modern methods of measuring the refractive state of the eye include wavefront sensors which make it possible to monitor both static and dynamic changes of the ocular wavefront while the eye observes ...a target positioned at different distances away from the eye. In addition to monitoring the ocular aberrations, wavefront refraction methods allow measurement of the accommodative response while viewing with the eye's habitual chromatic and monochromatic aberrations present, with these aberrations removed, and with specific aberrations added or removed. A large number of experiments describing the effects of accommodation on aberrations and vice versa are reviewed, pointing out the implications for fundamental questions related to the mechanism of accommodation.
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