Novel Approach to Increase the Energy-related Process Efficiency and Performance of Laser Brazing

AbstractAlthough laser brazing is well established, the energy-related efficiency of this joining method is quite low. That is because of low absorptivity of solid-state laser radiation, especially when copper base braze metals are used. Conventionally the laser beam is set close to the vertical axis and the filler wire is delivered under a flat angle. Therefore, the most of the utilized laser power is reflected and thus left unexploited. To address this situation an alternative processing concept for laser brazing, where the laser beam is leading the filler wire, has been investigated intending to make use of reflected shares of the laser radiation. Process monitoring shows, that the reflection of the laser beam can be used purposefully to preheat the substrate which is supporting the wetting and furthermore increasing the efficiency of the process. Experiments address a standard application from the automotive industry joining zinc coated steels using CuSi3Mn1 filler wire. Feasibility of the alternative processing concept is demonstrated, showing that higher processing speeds can be attained, reducing the required energy per unit length while maintaining joint properties

I2B is a Small Cytosolic Protein that Participates in Vacuole Fusion

Saccharomyces cerevisiae vacuole inheritance requires two low molecular weight activities, LMA1 and LMA2. LMA1 is a heterodimer of thioredoxin and protease B inhibitor 2 (IB2). Here we show that the second low molecular weight activity (LMA2) is monomeric IB2. Though LMA2 / IB2 was initially identified as a protease B inhibitor, this protease inhibitor activity is not related to its ability to promote vacuole fusion: ( i ) Low M r protease B inhibitors cannot substitute for LMA1 or LMA2, ( ii ) LMA1 and LMA2 promote the fusionof vacuoles from a strain that has no protease B, ( iii ) low concentrations of LMA2 that fully inhibit protease B do not promote vacuole fusion, and ( iv ) LMA1, in which is complexed with thioredoxin,is far more active than LMA2 / IB2 in promoting vacuole fusion and far less active in inhibiting protease B. These studies establish a new function for IB2

Comportamento ad alta temperatura di rivestimenti NiCrAlY prodotti mediante tecnica Laser Cladding

La tecnica Laser Cladding è un metodo alternativo alla spruzzatura termica per la produzione di rivestimentiresistenti alle alte temperature con una porosità molto bassa o addirittura nulla.Il presente studio ha riguardato il comportamento ad ossidazione di rivestimenti NiCrAlY ottenuti medianteLaser Cladding su substrati di Hastelloy X. Il comportamento ad ossidazione dei campioni rivestiti è statovalutato mediante prove in forno a circolazione d’aria alla temperatura di 1100°C con durate fino a 450 ore.I rivestimenti sono stati analizzati, prima e dopo le prove di ossidazione, mediante tecniche di microscopiaottica ed elettronica, microanalisi e diffrazione di raggi X. Dopo la deposizione il rivestimento ha mostratouna struttura dendritica con grani colonnari e porosità pressoché nulla. Dopo le prove di ossidazione l’analisimicroscopica ha mostrato la presenza di due distinti strati di ossidi, uno più esterno costituitoprevalentemente da ossidi di tipo spinello e uno strato più interno, continuo, costituito principalmenteda allumina. I risultati ottenuti suggeriscono che il rivestimento di NiCrAlY preparato per Laser Claddingè in grado di formare, ad alte temperature ed in atmosfera ossidativa, uno strato continuo di alluminache può proteggere il substrato dall’ossidazione

Studio per lo sviluppo di nuovi rivestimenti ceramico compositi impiegabili in sistemi abradibili

Una strategia per l’incremento delle prestazioni delle turbine a gas consiste nella riduzione del trafilamentodei gas nella zona ad alta temperatura della turbomacchina grazie alla riduzione della distanza tra lasommità delle palette e la copertura protettiva della cassa della turbina. A tal fine sono stati studiati sistemiabradibili realizzati mediante diverse tecniche. Sono stati realizzati sistemi compositi compositi a baseCoNiCrAlY/Al2O3 mediante tecnica Air Plasma Spray (APS), a base NiCrAlY/graphite mediante tecnica LaserCladding e barriere termiche spesse e porose. Le resistenze all’ossidazione e alla fatica termica dei rivestimentisono state valutate per mezzo di prove di ossidazione isoterma e ciclica. I rivestimenti compositiCoNiCrAlY/Al2O3 e NiCrAlY/graphite dopo 1000 ore a 1100°C non hanno mostrato rilevanti modificazionimicrostrutturali. La resistenza all’ossidazione dei nuovi rivestimenti compositi soddisfa le specifiche deiproduttori, gli “Original Equipment Manufacturer” (OEM). Le barriere termiche spesse e porose superano i testdi fatica termica imposti dalle procedure degli OEM. La durezza di tali rivestimenti suggerisce il loro uso incombinazione con palette dotate di rivestimento abrasivo sull’estremità. Le barriere termiche hanno mostratobuone caratteristiche di abradibilità

An untargeted multi-technique metabolomics approach to studying intracellular metabolites of HepG2 cells exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin

<p>Abstract</p> <p>Background</p> <p><it>In vitro </it>cell systems together with omics methods represent promising alternatives to conventional animal models for toxicity testing. Transcriptomic and proteomic approaches have been widely applied <it>in vitro </it>but relatively few studies have used metabolomics. Therefore, the goal of the present study was to develop an untargeted methodology for performing reproducible metabolomics on <it>in vitro </it>systems. The human liver cell line HepG2, and the well-known hepatotoxic and non-genotoxic carcinogen 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), were used as the <it>in vitro </it>model system and model toxicant, respectively.</p> <p>Results</p> <p>The study focused on the analysis of intracellular metabolites using NMR, LC-MS and GC-MS, with emphasis on the reproducibility and repeatability of the data. State of the art pre-processing and alignment tools and multivariate statistics were used to detect significantly altered levels of metabolites after exposing HepG2 cells to TCDD. Several metabolites identified using databases, literature and LC-nanomate-Orbitrap analysis were affected by the treatment. The observed changes in metabolite levels are discussed in relation to the reported effects of TCDD.</p> <p>Conclusions</p> <p>Untargeted profiling of the polar and apolar metabolites of <it>in vitro </it>cultured HepG2 cells is a valid approach to studying the effects of TCDD on the cell metabolome. The approach described in this research demonstrates that highly reproducible experiments and correct normalization of the datasets are essential for obtaining reliable results. The effects of TCDD on HepG2 cells reported herein are in agreement with previous studies and serve to validate the procedures used in the present work.</p

The evidence base for circulating tumour DNA blood-based biomarkers for the early detection of cancer: a systematic mapping review

Background: The presence of circulating cell-free DNA from tumours in blood (ctDNA) is of major importance to those interested in early cancer detection, as well as to those wishing to monitor tumour progression or diagnose the presence of activating mutations to guide treatment. In 2014, the UK Early Cancer Detection Consortium undertook a systematic mapping review of the literature to identify blood-based biomarkers with potential for the development of a non-invasive blood test for cancer screening, and which identified this as a major area of interest. This review builds on the mapping review to expand the ctDNA dataset to examine the best options for the detection of multiple cancer types. Methods: The original mapping review was based on comprehensive searches of the electronic databases Medline, Embase, CINAHL, the Cochrane library, and Biosis to obtain relevant literature on blood-based biomarkers for cancer detection in humans (PROSPERO no. CRD42014010827). The abstracts for each paper were reviewed to determine whether validation data were reported, and then examined in full. Publications concentrating on monitoring of disease burden or mutations were excluded. Results: The search identified 94 ctDNA studies meeting the criteria for review. All but 5 studies examined one cancer type, with breast, colorectal and lung cancers representing 60% of studies. The size and design of the studies varied widely. Controls were included in 77% of publications. The largest study included 640 patients, but the median study size was 65 cases and 35 controls, and the bulk of studies (71%) included less than 100 patients. Studies either estimated cfDNA levels non-specifically or tested for cancer-specific mutations or methylation changes (the majority using PCR-based methods). Conclusion: We have systematically reviewed ctDNA blood biomarkers for the early detection of cancer. Pre-analytical, analytical, and post-analytical considerations were identified which need to be addressed before such biomarkers enter clinical practice. The value of small studies with no comparison between methods, or even the inclusion of controls is highly questionable, and larger validation studies will be required before such methods can be considered for early cancer detection

Disruption of paired-associate learning in rat offspring perinatally exposed to dioxins

The prevalence of cognitive abnormalities in children has partly been ascribed to environmental chemical exposure. Appropriate animal models and tools for evaluating higher brain function are required to examine this problem. A recently developed behavioral test in which rats learn six unique flavor-location pairs in a test arena was used to evaluate paired-associate learning, a hallmark of the higher cognitive function that is essential to language learning in humans. Pregnant Long-Evans rats were dosed by gavage with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or 2,3,7,8-tetrabromodibenzo-p-dioxin (TBDD) at a dose of 0, 200, or 800 ng/kg (referred as Control, TCDD-200, TCDD-800, TBDD-200, or TBDD-800, hereafter) on gestational day 15, and the offspring was tested during adulthood. Paired-associate learning was found to be impaired in the TCDD-200 and TBDD-200 groups, but not in either group exposed to 800 ng/kg, the observations of which were ensured by non-cued trials. As for the emotional aspect, during habituation, the TCDD-200 and TBDD-200 groups showed significantly longer latencies to enter the test arena from a start box than the Control, TCDD-800, and TBDD-800 groups, suggesting that the TCDD-200 and TBDD-200 groups manifested anxiety-like behavior. Thus, both the chlorinated dioxin and its brominated congener affected higher brain function to a similar extent in a nearly identical manner. Use of the behavioral test that can evaluate paired-associate learning in rats demonstrated that in utero and lactational exposure to not only TCDD but also TBDD perturbed higher brain function in rat offspring in a nonmonotonic manner