This work shows how using specifically selected or designed waveforms in wireless power transfer (WPT) systems can lead to improved RF to dc conversion efficiency in rectifier circuits in the ...receiving end of these systems. Signals with different time domain waveforms are considered such as OFDM, white noise and chaotic waveforms, and the performance of a rectifier circuit operating at 433 MHz is evaluated when using these signals in comparison to a single carrier constant envelope signal. The performed experiments show that selecting high peak to average power ratio (PAPR) signals lead to improved RF-DC conversion efficiency in rectifier circuits.
Recently, the demand and studies related with Multi-Material Additive Manufacturing (MMAM) is continuously increasing. To uncover the essential knowledge hidden in the current mess of research works, ...this study, based on a simple review methodology, helps to identify and discuss the current knowledge about: limitations of software and hardware, the interface bonding strength of dissimilar materials, polymer reinforcement with continuous fiber, polymer-based multi-materials, and future and challenges. The review method starts with a list of topics to check: MMAM of polymers, the bonding strength between materials, knowledge gaps, and new development lines in polymer applications. Then, it continues with the search procedure on electronic databases and the inclusion and exclusion criteria definition. Finally, to help the discussion and assessment, the information is collected in tables.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Part appearance issues due to dimensional and shape inaccuracies (fidelity) hinder the use of additive manufacturing processes to obtain final products. Inaccuracies come from process parameter ...definition, post-processing operations, and the slicing process. Regarding the slicing procedure, the conventional approach is the indirect slicing of a tessellation that approximates the part model. Layer computation is straightforward in this method but introduces dimensional deviations for curvilinear surfaces. Direct slicing minimizes these deviations, but computation and layer representation are complex. This work blends both solutions, explaining how to build an improved tessellation from direct slices that can be introduced and processed in usual slicing programs. Two shapes , a simple hemisphere and a component of a retail product (a hair dryer nozzle), were printed by Fused Filament Fabrication (FFF), using conventional indirect slicing with different tessellation’s resolutions and the proposed Direct Slicing Tessellation (DST). The resulting samples were measured using a 3D scanner. Compared with a reference sample printed from a Computer-Aided Design (CAD) model discretized with a tolerance <6μm, maximum deviations were found on more areas of conventional indirect samples and with higher values (from 0.13 to 0.16 mm) than in the case of the DST samples (with maximum deviation of 0.1 mm at few points on the surface). Additionally, DST files are around ten times smaller than reference files. Finally, the deviation between the CAD model and the representation on the resulting surfaces of zebra stripes and mean curvature show that the proposed solution enhances the printed surface fidelity compared to the conventional indirect slicing.
Display omitted
•A tessellation from direct slicing DST was built in a CAD program using GrassHopper.•DST files can be used as conventional STL files in Additive Manufacturing.•Printed samples by material extrusion from conventional STL and proposed DST files.•3D scan measures: DST surface closer to reference than STL files.•DST file is ten times smaller than the STL with the finest resolution.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Cannabidiol (CBD) is a major non-psychotropic phytocannabinoid that attracted a great attention for its therapeutic potential against different pathologies including skin diseases. However, although ...the efficacy in preclinical models and the clinical benefits of CBD in humans have been extensively demonstrated, the molecular mechanism(s) and targets responsible for these effects are as yet unknown. Herein we characterized at the molecular level the effects of CBD on primary human keratinocytes using a combination of RNA sequencing (RNA-Seq) and sequential window acquisition of all theoretical mass spectrometry (SWATH-MS). Functional analysis revealed that CBD regulated pathways involved in keratinocyte differentiation, skin development and epidermal cell differentiation among other processes. In addition, CBD induced the expression of several NRF2 target genes, with heme oxygenase 1 (HMOX1) being the gene and the protein most upregulated by CBD. CRISPR/Cas9-mediated genome editing, RNA interference and biochemical studies demonstrated that the induction of HMOX1 mediated by CBD, involved nuclear export and proteasomal degradation of the transcriptional repressor BACH1. Notably, we showed that the effect of BACH1 on HMOX1 expression in keratinocytes is independent of NRF2. In vivo studies showed that topical CBD increased the levels of HMOX1 and of the proliferation and wound-repair associated keratins 16 and 17 in the skin of mice. Altogether, our study identifies BACH1 as a molecular target for CBD in keratinocytes and sets the basis for the use of topical CBD for the treatment of different skin diseases including atopic dermatitis and keratin disorders.
•CBD upregulates HMOX1 expression in keratinocytes in vitro and in vivo.•CBD induces nuclear export and degradation of BACH1.•CBD induces HMOX1 expression in an NRF2-independent manner.•CBD induces keratinocyte proliferation in vivo.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A rectenna design methodology combining electromagnetic (EM) simulation and harmonic balance (HB) analysis is presented. It consists of applying reciprocity theory to calculate the Thevenin ...equivalent circuit of the receiving antenna and optimizing the rectifying circuit parameters using HB analysis. The method is demonstrated by designing a 2.45-GHz rectenna based on a square aperture-coupled patch antenna with dual linear polarization. A compact implementation is achieved by etching a cross-shaped slot on the patch surface leading to a 32.5% patch side reduction. Voltage-doubling circuits convert the received RF power from each port to dc permitting the rectenna to receive arbitrarily polarized signals. The circuit is optimized for low input power densities and a simulated maximum efficiency of 38.2% was obtained for 1.5 nWcm -2 input RF power density at 2.43 GHz.
Despite their miniature brains, insects exhibit substantial variation in brain size. Although the functional significance of this variation is increasingly recognized, research on whether differences ...in insect brain sizes are mainly the result of constraints or selective pressures has hardly been performed. Here, we address this gap by combining prospective and retrospective phylogenetic-based analyses of brain size for a major insect group, bees (superfamily Apoidea). Using a brain dataset of 93 species from North America and Europe, we found that body size was the single best predictor of brain size in bees. However, the analyses also revealed that substantial variation in brain size remained even when adjusting for body size. We consequently asked whether such variation in relative brain size might be explained by adaptive hypotheses. We found that ecologically specialized species with single generations have larger brains—relative to their body size—than generalist or multi-generation species, but we did not find an effect of sociality on relative brain size. Phylogenetic reconstruction further supported the existence of different adaptive optima for relative brain size in lineages differing in feeding specialization and reproductive strategy. Our findings shed new light on the evolution of the insect brain, highlighting the importance of ecological pressures over social factors and suggesting that these pressures are different from those previously found to influence brain evolution in other taxa.
Background
The New Zealand mud snail
Potamopyrgus antipodarum
(Gray, 1843) is among the most widespread non-indigenous mollusk in the world. Based on a comprehensive phylogenetic analysis, the ...invasion of this species to central Chile, which is also the first record of this species from South America, is reported.
Results
Molecular analysis identified four populations of
P. antipodarum
in central Chile, Parque O'Higgins and Estero La Dehesa in Santiago city, and Estero Consuelo and the Chalinga River in Salamanca, a town located in a different basin. No sequence divergence was found among populations in the cytochrome
c
oxidase subunit I (COI) gene. Morphological and reproductive evidence is in agreement with these findings.
Conclusions
This is the first record of
P. antipodarum
in the Neotropical region. All populations contained only females with embryos or juvenile snails in their brood pouches suggesting that they are viable and well established. It is important to prevent the spread of
P. antipodarum
to other localities in Chile and other South American countries.
Additive Manufacturing (AM), also known as “three-dimensional printing”, has experienced significant advancements in recent years, including improvements in the mechanical properties of printed ...objects ...
The recent step towards “Sustainable Manufacturing (SM)” and efforts to reduce the consumption of cutting fluids have become the hot topic of research these days. Various efforts and strategies have ...been employed in the modern manufacturing sector to control the environmental pollutions generated from the application of cutting fluids. Therefore, in this holistic work, one such effort of reducing the consumption of cutting fluid is employed with the application of minimum quantity lubrication (MQL) and tool texturing. The turning trials were made on titanium alloy:Ti3Al2.5V alloy under dry and MQL conditions using textured and non-textured tools. The tool life, average surface roughness, specific cutting energy, air quality, and chip morphology were studied with the aid of the above-subjected conditions. In the end, the socio-economic aspects of all cooling conditions were studied and analyzed in the context of sustainable manufacturing. The outcomes of this study reveal that the combination of textured tools and minimum quantity lubrication considerably enhance the machining and sustainability performance as contended with other conditions. However, the air quality factor, i.e., PM2.5 particle generation, was less in the case of a textured tool with MQL conditions. Overall, it is worthy to mention that the combination of tool texturing and MQL cooling conditions has been considered as one of the potential combinations in the area of green machining.
Full text
Available for:
DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In the current paper, a methodology for the evaluation of fatigue crack shielding using 2D digital image correlation (DIC) is proposed. The crack tip shielding has been evaluated from the analysis of ...the displacements field observed at the vicinity of a growing fatigue crack. The proposed methodology is based on the evaluation of the stress intensity factors calculated from displacement fields measured around the crack tip using DIC. A comparative study employing four different mathematical models describing the crack tip displacements field (namely Westergaard, Williams and Muskhelishvili equations and Christopher, James and Patterson model) has been performed. For this purpose, a set of fatigue tests on aluminium 2024‐T3 compact tension specimens have been conducted at different R‐ratios. Results obtained from DIC technique have been compared with those obtained using compliance‐based methods. Results show a very good level of agreement illustrating the potential of the DIC technique for the analysis of crack shielding during fatigue crack growth.
Full text
Available for:
BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
PDF
