Residual stress measurement on Titanium Grade 5 and Inconel 625 thin dissimilar welded joints by contour method

Journal of Materials Science - Residual stress assessment is a key factor in engineering design owing to its impact on engineering properties of materials, structural components and welded joints....     

Multimedia summarization using social media content

In this work, we propose a novel multimedia summarization technique from Online Social Networks (OSNs). In particular, we model each Multimedia Social Network (MSN)—i.e. an OSN focusing on the management and sharing of multimedia information—using an hypergraph based approach and exploit influence analysis methodologies to determine the most important multimedia objects with respect to one or more topics of interest. Successively, we obtain from the list of candidate objects a multimedia summary using a summarization model together with an heuristics that aims to generate summaries with priority (with respect to some user keywords), continuity, variety and not receptiveness features. The performed experiments on Flickr shows the effectiveness of proposed approach.     

Physical properties of straw lignin-based polymer blends

Lignin powder, obtained from an abundant and low cost source, straw, through a low environmental impact process, the steam explosion, is used for the preparation of blends with low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE) and atactic polystyrene (PS).The obtained blends are processable through the conventional techniques used for thermoplastics; the modulus slightly increases for most lignin-polymer blends, while the tensile stress and elongation reduce. Moreover, lignin acts as a stabilzer against the UV radiation for PS, LDPE and LLDPE.     

Subcritical Growth of Indentation Median Cracks in Soda-Lime-Silica Glass

The influence of load and dwell time on the subcritical growth of indentation cracks was investigated. The behavior of soda-lime-silica glass in both active and inert environments was considered. Vickers indentations were obtained.using loads ranging from 1.96 to 39.2 N and the dwell time.at maximum load was varied between 5 s and 30 min. Indented samples were broken and the fracture surfaces.observed using optical microscopy. Anomalous crack shapes were obtained in air and water for long dwell times, particularly at higher indentation loads. The cracks were markedly circular in shape and substantially deeper than conventional median/radial indentation cracks, evidencing a time-dependent growth. Comparison of the measured crack depth with a theoretical analysis demonstrated that the appearance of the "circular" cracks was related to the subcritical growth of median cracks.     

Zeolite-Nafion composites as ion conducting membrane materials

Composite membranes formed of zeolitic fillers embedded in Nafion can be made by evaporating the solvents from a suspension of small zeolite crystals in a Nafion solution. Two natural zeolites were selected as fillers: chabazite and clinoptilolite. Membranes with various zeolite content were obtained. Composite membranes with zeolite content up to 40 vol.% exhibited uniform distribution of the zeolite fillers throughout the thickness, as ascertained by scanning electron microscopy (SEM), energy dispersive X-rays absorption (EDX) and ion conductivity measurements. Although more brittle than Nafion, these composite sheets retain—when hydrated—reasonable flexibility below 40 vol.% zeolite content. We have determined the hydrogen ion conductivity and the permeability of methanol molecules through these membranes (in the H⁺-form as well as in the Na⁺-form) in the temperature range 22-60 °C. We found that the presence of the zeolitic fillers in the membranes can bear notable changes of conductivity, permeability and selectivity with respect to membranes made out of sole Nafion.     

High‐Throughput Miniaturized Screening of Nanoparticle Formation via Inkjet Printing

The self‐assembly of specific polymers into well‐defined nanoparticles (NPs) is of great interest to the pharmaceutical industry as the resultant materials can act as drug delivery vehicles. In this work, a high‐throughput method to screen the ability of polymers to self‐assemble into NPs using a picoliter inkjet printer is presented. By dispensing polymer solutions in dimethyl sulfoxide (DMSO) from the printer into the wells of a 96‐well plate, containing water as an antisolvent, 50 suspensions are screened for nanoparticle formation rapidly using only nanoliters to microliters. A variety of polymer classes are used and in situ characterization of the submicroliter nanosuspensions shows that the particle size distributions match those of nanoparticles made from bulk suspensions. Dispensing organic polymer solutions into well plates via the printer is thus shown to be a reproducible and fast method for screening nanoparticle formation which uses two to three orders of magnitude less material than conventional techniques. Finally, a pilot study for a high‐throughput pipeline of nanoparticle production, physical property characterization, and cytocompatibility demonstrates the feasibility of the printing approach for screening of nanodrug delivery formulations. Nanoparticles are produced in the well plates, characterized for size and evaluated for effects on metabolic activity of lung cancer cells.     

Porcelain stoneware consolidation by flash sintering

Porcelain stoneware was consolidated by flash sintering under DC polarization using current densities in the range 4‐20 mA/mm². The results show the applicability of this innovative sintering technology to a material whose densification occurs by vitrification, thus allowing to extend the possible application field of flash sintering to traditional ceramics. Using appropriate current density, the flash‐ sintered samples are dense, homogeneous, and well‐vitrified. XRD and microstructural analysis points out the formation of primary mullite while secondary mullite is only sporadically observed. In addition, comparison between flash sintering and fast firing shows that the densification obtained in the selected ceramic system via the former route cannot be reproduced just by a rapid heating process.     

Design of Engineered Elastomeric Substrate for Stretchable Active Devices and Sensors

In the field of flexible electronics, emerging applications require biocompatible and unobtrusive devices, which can withstand different modes of mechanical deformation and achieve low complexity in the fabrication process. Here, the fabrication of a mesa‐shaped elastomeric substrate, supporting thin‐film transistors (TFTs) and logic circuits (inverters), is reported. High‐relief structures are designed to minimize the strain experienced by the electronics, which are fabricated directly on the pillars' surface. In this design configuration, devices based on amorphous indium‐gallium‐zinc‐oxide can withstand different modes of deformation. Bending, stretching, and twisting experiments up to 6 mm radius, 20% uniaxial strain, and 180° global twisting, respectively, are performed to show stable electrical performance of the TFTs. Similarly, a fully integrated digital inverter is tested while stretched up to 20% elongation. As a proof of the versatility of mesa‐shaped geometry, a biocompatible and stretchable sensor for temperature mapping is also realized. Using pectin, which is a temperature‐sensitive material present in plant cells, the response of the sensor shows current modulation from 13 to 28 °C and functionality up to 15% strain. These results demonstrate the performance of highly flexible electronics for a broad variety of applications, including smart skin and health monitoring.     

Sintering behavior of Ba/Sr celsian precursor obtained from zeolite‐A by ion‐exchange method

(Ba, Sr)‐exchanged zeolite A with composition Ba_0.74Sr_0.22Na_0.04Al₂Si₂O₈ was prepared by cation exchange; a mild thermal treatment converts into an amorphous phase. Successive crystallization and sintering behavior was studied by XRD, DTA, and thermodilatometric analysis. The results point out the activation of viscous flow sintering mechanisms between 900°C and 1050°C. The densification process starts when the amorphous phase reaches its glass transition temperature (897°C) and finishes when the material crystallizes forming hexacelsian. The application of an external pressure in such temperature range allows to achieve an almost complete densification, the material transforming at 1300°C into dense monoclinic celsian much below the typical processing temperature.     

计算机与建筑:非欧几里得空间的产生过程

首先做个假设,总体来说,讨论一个思想的起源几乎是不可能的。无论其是抽象或是具体的,它的产生过程总是被不确定性所掩盖。本文的主旨在于了解计算机如何生成建筑空间的一种新理念。特别是我们关注的非欧几里得空间,因为利用电子工具我们有可能借助软件容易地处理复杂的形状．从而释放出设计师的创造性。