The Effect of Lithium Disilicate Ceramic Surface Neutralization on Wettability of Silane Coupling Agents and Adhesive Resin Cements

This in vitro study was aimed to evaluate the possible changes in wettability of an etched glass ceramic surface to silane primers, adhesive resin and resin cement when the surface had been neutralized by a special neutralizing agent after etching. Rectangular shaped specimens were cut from the CAD blocks of an e-max lithium disilicate glass ceramic, cut specimens were sequentially polished and ultrasonically cleaned. All the specimens were etched for 20 s with 5% hydrofluoric acid and ultrasonically cleaned. Specimens were randomly assigned to one control group (without neutralization) and one treatment group (with neutralization) having 20 specimens each. The specimens of each group were further divided into two subgroups having 10 specimens each and tested to determine the effect of neutralizing agent on wettability of experimental and commercial silanes. Each subgroup specimen was tested for wettability to adhesive resin and commercial resin cement. Data were analyzed using two-way ANOVA. Neutralizing the ceramic surface did not show a significant effect on wettability to the silanes and the resin based materials, but the experimental silane showed better wettability than the commercial silane. The adhesive resin had statistically significant lower contact angle (high wettability) values than the commercial resin cement. The results of the current study suggested that the neutralizing agent did not have an impact on the wettability of the etched ceramic. However, there were differences in wetting properties of the silane primers, and adhesive resin versus resin composite luting cements.     

Collapsible impact energy absorbers: an overview

This paper reviews the common shapes of collapsible energy absorbers and the different modes of deformation of the most common ones. Common shapes include circular tubes, square tubes, frusta, struts, honeycombs, and sandwich plates. Common modes of deformation for circular tubes include axial crushing, lateral indentation, lateral flattening, inversion and splitting. Non-collapsible systems, such as lead extrusions or tube expansions, are considered to be beyond the scope of this review.     

Mild stress stimuli built into a non-immersive virtual environment can elicit actual stress responses

The experience of Virtual Reality (VR) can lead to unwanted or wanted psychological stress reactions. Highly immersive VR games for instance utilise extreme, life-threatening, or dangerous situations to achieve those responses from their players. There is also sufficient evidence that in clinical settings and specific situations, such as fear of heights or post-traumatic stress, virtual stimuli can lead to perceived stress for clients. However, there is a gap in research targeting everyday, mild emotional stimuli, which are neither extreme nor specific and which are not presented in an immersive system. To what extent can common stimuli in a non-immersive virtual environment elicit actual stress reactions for its users? We developed a desktop VR system and evaluated it in a study with 54 participants. We could show that virtual stimuli in a common, domestic family environment led to a significant increase in perceived stress as measured by quantitative (self-reports) and qualitative (semi-structured interviews analysed with a General Inductive Approach (GIA)) responses. The results also showed that the introduction of virtual stimuli induced significantly higher levels of perceived workload and sense of presence and led to different physiological reactions. These findings have implications for the design and implementation of non-immersive VR systems.     

Solubility of water in lime-alumina-silica melts

The water solubility in fused silicates of the CaO-SiO₂ and CaO-SiO₂-Al₂O₃ systems has been measured using a vacuum fusion technique. The melts were equilibrated with nitrogen as “carrier gas” containing an accurately known water content. The solubility of water increased on the addition of lime to the melts of both systems. The effect of alumina is initially, to decrease the solubility. Additions above about 20 wt pct at a constant basicity of 0.6 however raised the water solubility of lime-silica melts. From the plot of oxygen density against the hydrogen concentration of the silicate melts of the system lime-silica-alumina studied in this investigation, it may be concluded that free hydroxyls take up interstitial positions in the silicate network. Wustite additions to lime-silica melts of basicity equal to 1 do not appear to influence the water solubility, although the rate of gas absorption from the furnace atmosphere is accelerated significantly. P. L. SACHDEV, formerly Graduate Student, Institut für Eisenhüttenwesen R. W. Technische Hochschule Aachen, West Germany A. MAJDIČ, formerly Senior Engineer, Institut für Eisenhüttenwesen R. W. Technische Hochschule Aachen     

A Novel Gradient Boosted Energy Optimization Model (GBEOM) for MANET

Mobile Ad Hoc Network (MANET) is an infrastructure-less network that is comprised of a set of nodes that move randomly. In MANET, the overall performance is improved through multipath multicast routing to achieve the quality of service (quality of service). In this, different nodes are involved in the information data collection and transmission to the destination nodes in the network. The different nodes are combined and presented to achieve energy-efficient data transmission and classification of the nodes. The route identification and routing are established based on the data broadcast by the network nodes. In transmitting the data packet, evaluating the data delivery ratio is necessary to achieve optimal data transmission in the network. Furthermore, energy consumption and overhead are considered essential factors for the effective data transmission rate and better data delivery rate. In this paper, a Gradient-Based Energy Optimization model (GBEOM) for the route in MANET is proposed to achieve an improved data delivery rate. Initially, the Weighted Multi-objective Cluster-based Spider Monkey Load Balancing (WMC-SMLB) technique is utilized for obtaining energy efficiency and load balancing routing. The WMC algorithm is applied to perform an efficient node clustering process from the considered mobile nodes in MANET. Load balancing efficiency is improved with a higher data delivery ratio and minimum routing overhead based on the residual energy and bandwidth estimation. Next, the Gradient Boosted Multinomial ID3 Classification algorithm is applied to improve the performance of multipath multicast routing in MANET with minimal energy consumption and higher load balancing efficiency. The proposed GBEOM exhibits ∼4% improved performance in MANET routing.     

Towards an automatic extraction of synonyms for Quranic Arabic WordNet

In this paper, we developed an automatic extraction model of synonyms, which is used to construct our Quranic Arabic WordNet (QAWN) that depends on traditional Arabic dictionaries. In this work, we rely on three resources. First, the Boundary Annotated Quran Corpus that contains Quran words, Part-of-Speech, root and other related information. Second, the lexicon resources that was used to collect a set of derived words for Quranic words. Third, traditional Arabic dictionaries, which were used to extract the meaning of words with distinction of different senses. The objective of this work is to link the Quranic words of similar meanings in order to generate synonym sets (synsets). To accomplish that, we used term frequency and inverse document frequency in vector space model, and we then computed cosine similarities between Quranic words based on textual definitions that are extracted from traditional Arabic dictionaries. Words of highest similarity were grouped together to form a synset. Our QAWN consists of 6918 synsets that were constructed from about 8400 unique word senses, on average of 5 senses for each word. Based on our experimental evaluation, the average recall of the baseline system was 7.01 %, whereas the average recall of the QAWN was 34.13 % which improved the recall of semantic search for Quran concepts by 27 %.     

Urolithin A and B Alter Cellular Metabolism and Induce Metabolites Associated with Apoptosis in Leukemic Cells

Leukemia is persistently a significant cause of illness and mortality worldwide. Urolithins, metabolites of ellagic acid and ellagitannins produced by gut microbiota, showed better bioactive compounds liable for the health benefits exerted by ellagic acid and ellagitannins containing pomegranate and walnuts. Here, we assessed the potential antileukemic activities of both urolithin A and urolithin B. Results showed that both urolithin A and B significantly inhibited the proliferation of leukemic cell lines Jurkat and K562, among which urolithin A showed the more prominent antiproliferative capability. Further, urolithin treatment alters leukemic cell metabolism, as evidenced by increased metabolic rate and notable changes in glutamine metabolism, one-carbon metabolism, and lipid metabolism. Next, we evidenced that both urolithins equally promoted apoptosis in leukemic cell lines. Based on these observations, we concluded that both urolithin A and B alter leukemic cell metabolome, resulting in a halt of proliferation, followed by apoptosis. The data can be used for designing new combinational therapies to eradicate leukemic cells.     

RecAm: a collaborative context-aware framework for multimedia recommendations in an ambient intelligence environment

With an ever-increasing accessibility to different multimedia contents in real-time, it is difficult for users to identify the proper resources from such a vast number of choices. By utilizing the user’s context while consuming diverse multimedia contents, we can identify different personal preferences and settings. However, there is a need to reinforce the recommendation process in a systematic way, with context-adaptive information. The contributions of this paper are twofold. First, we propose a framework, called RecAm, which enables the collection of contextual information and the delivery of resulted recommendation by adapting the user’s environment using Ambient Intelligent (AmI) Interfaces. Second, we propose a recommendation model that establishes a bridge between the multimedia resources, user joint preferences, and the detected contextual information. Hence, we obtain a comprehensive view of the user’s context, as well as provide a personalized environment to deliver the feedback. We demonstrate the feasibility of RecAm with two prototypes applications that use contextual information for recommendations. The offline experiment conducted shows the improvement of delivering personalized recommendations based on the user’s context on two real-world datasets.     

Determining the effects of thermal conductivity on epoxy molds using profiled cooling channels with metal inserts

Polymer injection molds are generally manufactured with metallic materials, such as tool steel, which provide reliable working of molds and extended service life. The manufacture of injection molds with steel is a prolonged process because of the strength of steel. For a short prototype production run, one of the suitable choices could be the use of aluminum-filled epoxy material, which can produce a functional mold in a short time as compared with a conventionally machined tool. Aluminum-filled epoxy tooling is a good choice for short production runs for engineering applications, yet works best for relatively simple shapes. The advantages in relation to the fabrication of injection molds with epoxy-based materials include time saving in producing the mold, epoxy curing at ambient temperature, and ease of machining and post processing. Nevertheless, one major drawback of epoxy material is its poor thermal conductivity, which results in a relatively longer cooling time for epoxy injection molds. This study investigates some of the innovative ideas for enhancing the thermal conductivity for epoxy molds. The basic concept behind these ideas was to embed a highly thermally conductive metal insert within the mold between cavities with an innovative design of cooling channels called profiled cooling channels. This technique will increase the effective thermal conductivity of the epoxy mold, leading to the reduction in cooling time for the injection molded polymer part. Experimental analysis conducted in the current study also verified that the mold with profiled cooling channels and embedded metal insert has significantly reduced the cooling time.