Qualitative Analysis of Growth Parameters for PECVD Based Low Temperature Synthesis of Graphene Using Design of Experiments

Determination of key factors and parameters is necessary to design any process when number of factors are large. Design of Experiments technique is an important statistical tool to serve the purpose. This work demonstrates a method to perform qualitative analysis in order to determine cardinal control factors for Graphene growth at low temperature values using Fractional Factorial design. Graphene is synthesized using Plasma Enhanced Chemical Vapor Deposition (PECVD) method in this work. Attribute Response Analysis suggests that Graphene growth temperature, deposition time and RF power are important controlling factors. This is verified by Graphene growth using the predicted recipe

Degradation Analysis of Silicone as Encapsulation and Molding Material in High Power LEDs

Applications of LEDs have increased significantly, and increasing outdoor applications are observed. Some outdoor applications require high reliability as their failure can lead to hazardous consequences. Examples are their applications in automotive, street lamp lighting etc. To ensure the reliability of LEDs in outdoor applications, reliability test that include humidity on the LEDs must be done. However, it is found that accelerated life test of LEDs at high humidity level cannot be extrapolated to standard condition of lower humidity as the mechanism of degradation depends critically on humidity level. In fact, the degradation of LEDs in outdoor applications is mainly due to the degradation of their encapsulation and housing materials (or called packaging material as a whole) instead of the semiconductor chip itself. The decrease in lumen is the results of crack and discoloration of the LED packaging material. Detail understanding of the failure physics of the packaging material for LED under humidity is needed for extrapolation performed at accelerated stress condition so that LED luminary reliability can be predicted. This chapter reviews the different types of degradation physics of the packaging material using ab-initio simulation with excellent verification from experiments. The method of extrapolation is therefore derived from the physics-based model after detailed understanding of the degradation physics of LEDs. The model also provides strategy for industry to prolong the usage of LEDs in outdoor applications, either through materials or operating conditions selection

Compressive strength of lightweight foamed concrete with charcoal as a sand replacement

Foamed concrete, a high performance concrete with lightweight properties and strength-enhancing additive have drawn the attention of researchers towards a sustainable life style. This paper presents a study of the compressive strength of various charcoal-filled lightweight foamed concrete (LFC), where waste materials, water-reducing agent and strength enhancement additives are introduced to the mix design in order to obtain further lightweight concrete. Five series of experimental tests were carried out, where Series 1 tested optimum ratio of silica fume and superplasticizer, Series 2 depicted the design mix of sand replacement with charcoal, Series 3 described the mix for additives, Series 4 illustrated effect of aggregate size for charcoal and different densities, as well as Series 5 was the conventional design mix ratio. The fresh and harden densities have been recorded while the shrinkage of LFC had also been observed during the casting and curing period. From the results, the mixture with silica fume replacing the cement was found to have a lower compressive strength as compared to mixtures with a full portion of cement. The strength reductions ranged between 62 to 80% for the mix with no superplasticizer and 29 to 82% for the mix with superplasticizer, which was obtained from the 20 to 50% of cement replacement with silica fume. Foamed concrete with superplasticizer achieved 66% of higher compressive strength. However, concrete expansion and spalling were discovered at the later concrete age of Series 5 which degraded the concrete strength. From this study, it was found that charcoal with low specific gravity is a suitable for full sand replacement in foamed concrete prior to the treatment that can lower its alkalinity

Applications of multi-walled carbon nanotube in electronic packaging

Thermal management of integrated circuit chip is an increasing important challenge faced today. Heat dissipation of the chip is generally achieved through the die attach material and solders. With the temperature gradients in these materials, high thermo-mechanical stress will be developed in them, and thus they must also be mechanically strong so as to provide a good mechanical support to the chip. The use of multi-walled carbon nanotube to enhance the thermal conductivity, and the mechanical strength of die attach epoxy and Pb-free solder is demonstrated in this work

Targeting codon 158 p53-mutant cancers via the induction of p53 acetylation

Abstract: Gain of function (GOF) DNA binding domain (DBD) mutations of TP53 upregulate chromatin regulatory genes that promote genome-wide histone methylation and acetylation. Here, we therapeutically exploit the oncogenic GOF mechanisms of p53 codon 158 (Arg158) mutation, a DBD mutant found to be prevalent in lung carcinomas. Using high throughput compound screening and combination analyses, we uncover that acetylating mutp53R158G could render cancers susceptible to cisplatin-induced DNA stress. Acetylation of mutp53R158G alters DNA binding motifs and upregulates TRAIP, a RING domain-containing E3 ubiquitin ligase which dephosphorylates IĸB and impedes nuclear translocation of RelA (p65), thus repressing oncogenic nuclear factor kappa-B (NF-ĸB) signaling and inducing apoptosis. Given that this mechanism of cytotoxic vulnerability appears inapt in p53 wild-type (WT) or other hotspot GOF mutp53 cells, our work provides a therapeutic opportunity specific to Arg158-mutp53 tumors utilizing a regimen consisting of DNA-damaging agents and mutp53 acetylators, which is currently being pursued clinically

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe