Strain self-sensing tailoring in functionalised carbon nanotubes/epoxy nanocomposites in response to electrical resistance change measurement

Carbon nanotubes (CNTs) are inherently multifunctional, conductive and possess piezo-resistive characteristics. Aiming at the multi-functionality of materials, nanocomposites made of epoxy resin with embedded CNTs are a promising solution for strain self-sensing applications. A critical parameter to achieve repeatable and reliable measure is the CNTs dispersion state in the resin. This study investigated the effect of CNTs concentration (0.01 wt% and 0.1 wt%), with different loading of surfactant Triton X-100, (0.0%, 0.2%, 0.5% and 1.0%) on strain sensing in terms of sensitivity and linearity based on electrical resistance data. The CNTs were synthesised directly using an injection floating catalyst chemical vapor deposition (ICCVD) process and their quality was characterised by Raman spectroscopy and scanning electron microscopy. Only the epoxy modfied with 0.1 wt% CNTs exhibited sufficient piezo-resistivity for the resistance measurements, and those with 0.01 wt% CNTs did not show sufficiently measurable conductivity so were excluded in our study, since their CNTs were highly entangled, and conductive network failed to be established. It was observed that, with 0.1 wt% CNTs, adding 0.5% content of the surfactant improved gauge factor. With more content of the surfactant (1.0 %), surprisingly, we observed a drop of gauge factor by the order of two. Therefore, by comparing the conductivity change between 1.0% and 0.5% surfactant, we postulated that the relatively high content surfactant has reached critical micelle concentration, and negatively affects CNTs dispersion state. The research presented in this article shows that moderate content of surfactant could improve piezoresistivity gauge factor while excessive surfactant could cause adverse effect

Contactless Dielectric Process Monitoring (CDPM) of Polymer Composites Manufacturing

A feasibility study has been performed systematically to develop a real-time contactless measurement of the dielectric properties (DP) of composite surface by means of a high-frequency, free-space vector network analyser (VNA) associated with one steel conical horn antenna (mono- static method). Examinations of the dielectric spectra of thermoset epoxy systems over a frequency range of 1kHz to 10GHz have show

Recent progress in biohydrometallurgy and microbial characterisation

Since the discovery of microbiological metal dissolution, numerous biohydrometallurgical approaches have been developed to use microbially assisted aqueous extractive metallurgy for the recovery of metals from ores, concentrates, and recycled or residual materials. Biohydrometallurgy has helped to alleviate the challenges related to continually declining ore grades by transforming uneconomic ore resources to reserves. Engineering techniques used for biohydrometallurgy span from above ground reactor, vat, pond, heap and dump leaching to underground in situ leaching. Traditionally biohydrometallurgy has been applied to the bioleaching of base metals and uranium from sulfides and biooxidation of sulfidic refractory gold ores and concentrates before cyanidation. More recently the interest in using bioleaching for oxide ore and waste processing, as well as extracting other commodities such as rare earth elements has been growing. Bioprospecting, adaptation, engineering and storing of microorganisms has increased the availability of suitable biocatalysts for biohydrometallurgical applications. Moreover, the advancement of microbial characterisation methods has increased the understanding of microbial communities and their capabilities in the processes. This paper reviews recent progress in biohydrometallurgy and microbial characterisatio

Tailoring of Thermo-Mechanical Properties of Hybrid Composite-Metal Bonded Joints

Metallic substrates and polymer adhesive in composite-metal joints have a relatively large coefficient of thermal expansion (CTE) mismatch, which is a barrier in the growing market of electric vehicles and their battery structures. It is reported that adding carbon nanotubes (CNTs) to the adhesive reduces the CTE of the CNT-enhanced polymer adhesive multi-material system, and therefore when used in adhesively bonded joints it would, theoretically, result in low CTE mismatch in the joint system. The current article presents the influence of two specific mass ratios of CNTs on the CTE of the enhanced polymer. It was observed that the addition of 1.0 wt% and 2.68 wt% of multi-walled CNTs (MWCNTs) decreased the CTE of the polymer adhesive from 7.5×10−5 °C−1 (pristine level) to 5.87×10−5 °C−1 and 4.43×10−5 °C−1, respectively, by 22% and 41% reductions

Development of carbonaceous tin-based solder composite achieving unprecedented joint performance

Weight reduction and improved strength are two common engineering goals in the joining sector to benefit transport, aerospace, and nuclear industries amongst others. Here, in this paper, we show that the suitable addition of carbon nanomaterials to a tin-based solder material matrix (C-Solder® supplied by Cametics Ltd.) results in two-fold strength of soldered composite joints. Single-lap shear joint experiments were conducted on soldered aluminium alloy (6082 T6) substrates. The soldering material was reinforced in different mix ratios by carbon black, graphene, and single-walled carbon nanotubes (SWCNT) and benchmarked against the pristine C-solder®. The material characterisation was performed using Vickers micro-indentation, differential scanning calorimetry and nano-indentation, whereas functional testing involved mechanical shear tests using single-lap aluminium soldered joints and creep tests. The hardness was observed to improve in all cases except for the 0.01 wt.% graphene reinforced solders, with 5% and 4% improvements in 0.05 carbon black and SWCNT reinforced solders, respectively. The maximum creep indentation was noted to improve for all solder categories with maximum 11% and 8% improvements in 0.05 wt.% carbon black and SWCNT reinforced ones. In general, the 0.05 wt.% nanomaterial reinforced solders promoted progressive cohesion failure in the joints as opposed to instantaneous fully de-bonded failure observed in pristine soldered joints, which suggests potential application in high-performance structures where no service load induced adhesion failure is permissible (e.g. aerospace assemblies). The novel innovation developed here will pave the way to achieving high-performance solder joining without carrying out extensive surface preparations

Integration of bow-tie plasmonic nano-antennas on tapered fibers

FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPIn this article, a new and flexible approach to control the electric field enhancement of bow-tie nano-antennas by integrating them on the lateral of a tapered optical fiber is proposed. The device is driven by a Q-switched laser and the performance of a fabricated nano-antenna in a quartz slide is tested by a Surface Enhanced Raman Scattering (SERS) experiment. A refractive index sensing experiment is also performed and a sensitivity of (240 +/- 30) nm/RIU is found in the 1.33-1.35 index range.25889868996FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP2014/50632-6The Asian Office of Aerospace Research and Development (AOARD US Air Force FA2386-15-1-4084); Australian Research Council (ARC LP160100253); and Sao Paulo Research Foundation (FAPESP) (#2014/50632-6)

Loss of tumor suppressor NF1 activates HSF1 to promote carcinogenesis

Intrinsic stress response pathways are frequently mobilized within tumor cells. The mediators of these adaptive mechanisms and how they contribute to carcinogenesis remain poorly understood. A striking example is heat shock factor 1 (HSF1), master transcriptional regulator of the heat shock response. Surprisingly, we found that loss of the tumor suppressor gene neurofibromatosis type 1 (Nf1) increased HSF1 levels and triggered its activation in mouse embryonic fibroblasts. As a consequence, Nf1[superscript –/–] cells acquired tolerance to proteotoxic stress. This activation of HSF1 depended on dysregulated MAPK signaling. HSF1, in turn, supported MAPK signaling. In mice, Hsf1 deficiency impeded NF1-associated carcinogenesis by attenuating oncogenic RAS/MAPK signaling. In cell lines from human malignant peripheral nerve sheath tumors (MPNSTs) driven by NF1 loss, HSF1 was overexpressed and activated, which was required for tumor cell viability. In surgical resections of human MPNSTs, HSF1 was overexpressed, translocated to the nucleus, and phosphorylated. These findings reveal a surprising biological consequence of NF1 deficiency: activation of HSF1 and ensuing addiction to this master regulator of the heat shock response. The loss of NF1 function engages an evolutionarily conserved cellular survival mechanism that ultimately impairs survival of the whole organism by facilitating carcinogenesis.United States. Army Medical Research and Materiel Command (Neurofibromatosis Research Program)Kathy and Curt Marble Cancer Research Fun

Status of Groundnut Research and Production in South Asia

South Asia, comprising Bangladesh, Bhutan, India, Myanmar, Nepal, Pakistan, and Sri Lanka, accounts for about 43.4% of the world groundnut (Arachis hypogaea) area (8.6 million ha) and 35.7% of production (8.1 million t). The period coinciding with the Southwest monsoon is the main growing season in the region although the crop is grown in more than one season in India, Myanmar, and Sri Lanka. The low average yields of groundnut in the region result from: raising the crop mostly under rainfed conditions on marginal and submarginal lands with low levels of inputs, use of varieties with long maturity periods, susceptibility of the crop to a plethora of insect pests and diseases, and nonavailability of efficient farm machinery and quality seed. All countries in the region made sustained efforts in the development of improved technology, including development of high-yielding varieties, improved agronomic practices, new and efficient strains of Bradyrhizobium, and efficient and economical plant protection schedules for the control of major insect pests and diseases. When tested in the farmers' fields, the technology indicated much unrealized yield poten- tial. The future crop improvement research in the region aims to concentrate on the areas of crop duration. fresh seed dormancy, resistance/tolerance to major biotic stresses, seed quality and production. and design and development of efficient farm implements and machinery. To realizefull impact of research on groundnut production in the region, it is important to ensure adequate support price and market to the crop. The International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) has contributed substantially towards the development of improved cultivars as well as offering training facilities to accomplish better human resource development in the region

Protein Kinase A Binds and Activates Heat Shock Factor 1

BACKGROUND. Many inducible transcription factors are regulated through batteries of posttranslational modifications that couple their activity to inducing stimuli. We have studied such regulation of Heat Shock Factor 1 (HSF1), a key protein in control of the heat shock response, and a participant in carcinogenisis, neurological health and aging. As the mechanisms involved in the intracellular regulation of HSF1 in good health and its dysregulation in disease are still incomplete we are investigating the role of posttranslational modifications in such regulation. METHODOLOGY/PRINCIPAL FINDINGS. In a proteomic study of HSF1 binding partners, we have discovered its association with the pleiotropic protein kinase A (PKA). HSF1 binds avidly to the catalytic subunit of PKA, (PKAca) and becomes phosphorylated on a novel serine phosphorylation site within its central regulatory domain (serine 320 or S320), both in vitro and in vivo. Intracellular PKAca levels and phosphorylation of HSF1 at S320 were both required for HSF1 to be localized to the nucleus, bind to response elements in the promoter of an HSF1 target gene (hsp70.1) and activate hsp70.1 after stress. Reduction in PKAca levels by small hairpin RNA led to HSF1 exclusion from the nucleus, its exodus from the hsp70.1 promoter and decreased hsp70.1 transcription. Likewise, null mutation of HSF1 at S320 by alanine substitution for serine led to an HSF1 species excluded from the nucleus and deficient in hsp70.1 activation. CONCLUSIONS. These findings of PKA regulation of HSF1 through S320 phosphorylation add to our knowledge of the signaling networks converging on this factor and may contribute to elucidating its complex roles in the stress response and understanding HSF1 dysregulation in disease.National Institutes of Health (2RO1CA047407, RO1CA077465

Co-chaperones are limiting in a depleted chaperone network

To probe the limiting nodes in the chaperoning network which maintains cellular proteostasis, we expressed a dominant negative mutant of heat shock factor 1 (dnHSF1), the regulator of the cytoplasmic proteotoxic stress response. Microarray analysis of non-stressed dnHSF1 cells showed a two- or more fold decrease in the transcript level of 10 genes, amongst which are the (co-)chaperone genes HSP90AA1, HSPA6, DNAJB1 and HSPB1. Glucocorticoid signaling, which requires the Hsp70 and the Hsp90 folding machines, was severely impaired by dnHSF1, but fully rescued by expression of DNAJA1 or DNAJB1, and partially by ST13. Expression of DNAJB6, DNAJB8, HSPA1A, HSPB1, HSPB8, or STIP1 had no effect while HSP90AA1 even inhibited. PTGES3 (p23) inhibited only in control cells. Our results suggest that the DNAJ co-chaperones in particular become limiting in a depleted chaperoning network. Our results also suggest a difference between the transcriptomes of cells lacking HSF1 and cells expressing dnHSF1