Multifunctional ultralight,recoverable, piezoresistive,and super thermal insulating SiC nanowire sponges

Ultralight three-dimensional (3D) architectured silicon carbide (SiC) nanowire sponges with integrated properties of recoverable compressibility, outstanding high-temperature thermal and chemical stability, and fire-retardance have been actively pursued in recent years. However, efficient construction of SiC nanowire sponges with well-controlled overall shapes and distribution of SiC nanowires remains challenging. Herein, by coupling the electrospinning technique and carbothermal reduction process, we have developed a new fabrication process for highly porous and free-standing 3D SiC nanowire (SiCNW) sponges with closely attached nanowires through thermal treatment of stacked electrospun PAN/SiO₂ nanofiber membranes. The resulting SiCNW sponges possess ultralow density (∼29 mg cm⁻³), excellent compressive recoverability from large compressive deformation (up to 40% strain), and fatigue resistance, which endow them with excellent piezoresistive sensing capability under a variety of complex conditions. Furthermore, the sponges display superb thermal insulation (thermal conductivity of 24 mW m⁻¹K⁻¹) and fire-retardance. We believe that the present process provides technical clues for the development of other multifunctional ceramic sponges, and that further development of these ultralight multifunctional ceramic sponges offers potential for the design of advanced components for application in harsh engineering environments.     

Effect of commercial rye whole-meal bread on postprandial blood glucose and gastric emptying in healthy subjects

Background  

The intake of dietary fibre has been shown to reduce the risk of developing diabetes mellitus. The aim of this study was to compare the effects of commercial rye whole-meal bread containing whole kernels and white wheat bread on the rate of gastric emptying and postprandial glucose response in healthy subjects.     

In situ measurement of pitted area by diffuse light scattering

In studies of pitting corrosion, there is often a need for monitoring the size of growing pits in situ as well as the need for a rapid assessment of the extent of pitting damage ex situ on a large number of test specimens. The well-known method of determining surface roughness by diffuse light scattering has been adapted to satisfy both needs. In situ measurements with aluminium alloys immersed in NaCl solutions indicate that early stages of pit propagation can be monitored accurately. Furthermore, measurements on pre-pitted aluminium show that the technique is suitable for rapid, quantitative determinations of a pitted area up to a fraction of 40%.     

Dynamic crack propagation in large steel specimens

Dynamic fracture experiments on crack initiation and crack growth in single edge bend specimens are performed. The impact velocity is in the range of 14 to 50 m/s and the specimen size is 320×75 mm with a thickness varying from 18 to 40 mm. The experiments are recorded by high speed photography.Two different steel qualities are investigated and their constitutive characterisation are obtained from uni-axial tension tests and shear tests with strain rates in the range 10⁻⁴ to 10³ s⁻¹ and tension tests at temperatures between −196 and 600°C.One of the materials exhibits a transition from a ductile dimple fracture to a brittle cleavage fracture as the loading velocity increases and as the specimen thickness increases. Scanning electron microscope fractographs show that the density of plastic bridges within cleavage ligaments decreases with increasing impact velocity and with increasing specimen thickness. It is also noted that the local crack propagation direction deflects from the global one in cleavage fracture areas with a high density of plastic bridges.The other material fails in a ductile mode in all the investigated cases.     

A method for landscape regionalization based on fuzzy membership signatures

The aim of this paper is to present a new method for regionalization that can be used in landscape analysis and planning. The approach in this study concentrates on the possibility to use membership functions developed from training sites as a mean to characterize whole regions. Instead of traditional classification routines a fuzzy method was developed. The method is described with an example from a study area located in Sweden. Pre-classified and unclassified satellite data were used in the study. The frequency distribution of three land cover types was calculated for three different training sites. The frequency distributions were transformed into membership functions. As such they describe the graded membership for every frequency pixel to all the training sites. Thereafter, were the membership images combined through a weighted linear combination. The result shows the membership for every location in the study area to one of the training sites. The images were also classified into one resulting image showing the crisp regions of the study area. An accuracy assessment of the method was performed. The result showed an overall classification accuracy of 86% compared to existing regional divisions of the study area.     

Multiple channel detection of steady-state visual evoked potentials for brain-computer interfaces

In this paper, novel methods for detecting steady-state visual evoked potentials using multiple electroencephalogram (EEG) signals are presented. The methods are tailored for brain-computer interfacing, where fast and accurate detection is of vital importance for achieving high information transfer rates. High detection accuracy using short time segments is obtained by finding combinations of electrode signals that cancel strong interference signals in the EEG data. Data from a test group consisting of 10 subjects are used to evaluate the new methods and to compare them to standard techniques. Using 1-s signal segments, six different visual stimulation frequencies could be discriminated with an average classification accuracy of 84%. An additional advantage of the presented methodology is that it is fully online, i.e., no calibration data for noise estimation, feature extraction, or electrode selection is needed.     

Modeling of uniaxial compression in a 3D periodic re-entrant lattice structure

In this study, the behavior of a parametric 3D re-entrant dodecahedron lattice structure with negative Poisson’s ratio was studied. Four geometrical configurations for the re-entrant dodecahedron were designed, and the relationship between the mechanical properties and the design parameters was determined through beam theory. Samples were fabricated successfully via electron beam melting. Compressive tests as well as finite element analysis (FEA) were performed, and the results were compared with theoretical predictions. The modeling yielded explicit analytical equations of various mechanical properties including Poisson’s ratios, modulus and strength, and the compressive strength and the modulus from the prediction match well with the experiments, as well as the FEA results. The methodology used by this study also demonstrated a feasible approach to design 3D auxetic cellular structure for various applications.     

Distinctive exotic flavor and aroma compounds of some exotic tropical fruits and berries: a review

The characteristic flavor of exotic tropical fruits is one of their most attractive attributes to consumers. In this article, the enormous diversity of exotic fruit flavors is reviewed. Classifying some of the exotic fruits into two classes on the basis of whether esters or terpenes predominate in the aroma was also attempted. Indeed, as far as exotic tropical fruits are concerned, the majority of fruits have terpenes predominating in their aroma profile. Some of the fruits in this group are the Amazonian fruits such as pitanga, umbu-caja, camu-camu, garcinia, and bacuri. The ester group is made up of rambutan, durians, star fruit, snake fruit, acerola, tamarind, sapodilla, genipap, soursop, cashew, melon, jackfruit, and cupuacu respectively. Also, the role of sulphur-volatiles in some of the exotic fruits is detailed.