Deposit shape control for local repair and welding by cold spray

Cold spray (CS) has proven to be a versatile deposition method with considerable capabilities in multiple fields including coating, additive manufacturing, and repair. Despite the significant progress in new applications of cold spray, there are still several challenges associated with controlling the shape of cold spray deposits that consequently affect their range of application and functionality. In this study, we discuss and demonstrate a new application of CS to connect adjoining edges along with repair local damages, focusing on deposit shape prediction. To do so, we start by proposing a numerical model that can predict the CS deposit geometry, by providing specific input parameters for a given set of particle and substrate properties, substrate geometry and nozzle position. Then we employ this numerical method to design the toolpath required for filling the artificial local damages and/or the welding grooves with controlled geometries. Through comparing the predictions with the shape of experimentally obtained depositions, we propose some corrections for the model. In both local repair and welding cases, the experimental results show a great resemblance to the predicted deposit profile and after applying the corrective measures, to the deposit height

Insights on Structural Evolution and Charge Storage Mechanism of Na4Mn9O18 as Active Material for Aqueous Rechargeable Sodium-Ion Storage Systems

As a renewable and sustainable energy storage technology, aqueous rechargeable sodium-ion storage systems have raised great interest due to environmental friendliness, safety and low cost. Unlike conventional lithium-ion batteries, aqueous sodium-ion systems have some distinct advantages for large-scale stationary electric storage, such as the abundant natural resource of Na and the possibility to achieve long-term stability and reversibility. In addition, aqueous electrolytes are inherently safer and more eco-friendly than organic electrolytes [1]. On the other hand, the use of aqueous electrolytes poses significant challenges in the selection of electrode materials. First, their redox potentials should be within the electrochemical stability window of water. Second, the side reactions between electrode materials and H2O or residual O2 may tremendously affect their cyclic stability [2]. Among the different eligible materials, channeled structure Na4Mn9O18 (NMO) is still one of the most promising candidate as cathodic material for aqueous Na-ion storage systems, because of its abundance, low price ($7.6 kg-1[3]), relatively high theoretical capacity (121 mAh g-1), non-toxicity, and simple synthesis by different routes. However, this material has yet to be characterized in detail in terms of its storage mechanisms and stability performance in aqueous environment. In this study, we undertake an in depth characterization of the kinetics of NMO electrode processes in 1 M Na2SO4 electrolyte, within its safe potential window in thiselectrolyte, namely 0.25-1.1 VSHE, as defined in the present work. We use cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) to deconvolve the complex behavior of this system and discriminate the different contributions of double-layer capacitance, pseudocapacitance and sodium ion insertion to charge/discharge at varying potential. First, by the power law analysis of voltammetry we identify kinetic processes and make an evaluation of their respective contribution; then, the analysis and modeling of EIS measurements, performed at varying potential after equilibration of the system, allow us to calculate the currents associated with the above processes at varying potential and as a function of the frequency. In particular, the EIS method proves that the diffusional or intercalation contribution is dominant over the entire safe potential window. The latter methodology holds great promise to be a powerful tool for an effective deconvolution of the complex behavior of the NMO / aqueous electrolyte system, enabling an in depth understanding of the role of different processes in its dynamic performance

The DNA demethylating agent decitabine activates the TRAIL pathway and induces apoptosis in acute myeloid leukemia

Although epigenetic drugs have been approved for use in selected malignancies, there is significant need for a better understanding of their mechanism of action. Here, we study the action of a clinically approved DNA-methyltransferase inhibitor - decitabine (DAC) - in acute myeloid leukemia (AML) cells. At low doses, DAC treatment induced apoptosis of NB4 Acute Promyelocytic Leukemia (APL) cells, which was associated with the activation of the extrinsic apoptotic pathway. Expression studies of the members of the Death Receptor family demonstrated that DAC induces the expression of TNF-related apoptosis-inducing ligand (TRAIL). Upregulation of TRAIL, upon DAC treatment, was associated with specific epigenetic modifications induced by DAC in the proximity of the TRAIL promoter, as demonstrated by DNA demethylation, increased DNaseI sensitivity and histone acetylation of a non-CpG island, CpG-rich region located 2kb upstream to the transcription start site. Luciferase assay experiments showed that this region behave as a DNA methylation sensitive transcriptional regulatory element. The CpG regulatory element was also found methylated in samples derived from APL patients. These findings have been confirmed in the non-APL, AML Kasumi cell line, suggesting that this regulatory mechanism may be extended to other AMLs. Our study suggests that DNA methylation is a regulatory mechanism relevant for silencing of the TRAIL apoptotic pathway in leukemic cells, and further elucidates the mechanism by which epigenetic drugs mediate their anti-leukemic effects

Novel non-covalent LSD1 inhibitors endowed with anticancer effects in leukemia and solid tumor cellular models

LSD1 is a histone lysine demethylase proposed as therapeutic target in cancer. Chemical modifications applied at C2, C4 and/or C7 positions of the quinazoline core of the previously reported dual LSD1/G9a inhibitor 1 led to a series of non-covalent, highly active, and selective LSD1 inhibitors (2–4 and 6–30) and to the dual LSD1/G9a inhibitor 5 that was more potent than 1 against LSD1. In THP-1 and MV4-11 leukemic cells, the most potent compounds (7, 8, and 29) showed antiproliferative effects at sub-micromolar level without significant toxicity at 1 μM in non-cancer AHH-1 cells. In MV4-11 cells, the new derivatives increased the levels of the LSD1 histone mark H3K4me2 and induced the re-expression of the CD86 gene silenced by LSD1, thereby confirming the inhibition of LSD1 at cellular level. In breast MDA-MB-231 as well as in rhabdomyosarcoma RD and RH30 cells, taken as examples of solid tumors, the same compounds displayed cell growth arrest in the same IC50 range, highlighting a crucial anticancer role for LSD1 inhibition and suggesting no added value for the simultaneous G9a inhibition in these tumor cell lines

Biochemical, structural, and biological evaluation of tranylcypromine derivatives as inhibitors of histone demethylases LSD1 and LSD2.

LSD1 and LSD2 histone demethylases are implicated in a number of physiological and pathological processes, ranging from tumorigenesis to herpes virus infection. A comprehensive structural, biochemical, and cellular study is presented here to probe the potential of these enzymes for epigenetic therapies. This approach employs tranylcypromine as a chemical scaffold for the design of novel demethylase inhibitors. This drug is a clinically validated antidepressant known to target monoamine oxidases A and B. These two flavoenzymes are structurally related to LSD1 and LSD2. Mechanistic and crystallographic studies of tranylcypromine inhibition reveal a lack of selectivity and differing covalent modifications of the FAD cofactor depending on the enantiomeric form. These findings are pharmacologically relevant, since tranylcypromine is currently administered as a racemic mixture. A large set of tranylcypromine analogues were synthesized and screened for inhibitory activities. We found that the common evolutionary origin of LSD and MAO enzymes, despite their unrelated functions and substrate specificities, is reflected in related ligand-binding properties. A few compounds with partial enzyme selectivity were identified. The biological activity of one of these new inhibitors was evaluated with a cellular model of acute promyelocytic leukemia chosen since its pathogenesis includes aberrant activities of several chromatin modifiers. Marked effects on cell differentiation and an unprecedented synergistic activity with antileukemia drugs were observed. These data demonstrate that these LSD1/2 inhibitors are of potential relevance for the treatment of promyelocytic leukemia and, more generally, as tools to alter chromatin state with promise of a block of tumor progression

NA-Seq: a discovery tool for the analysis of chromatin structure and dynamics during differentiation

It is well established that epigenetic modulation of genome accessibility in chromatin occurs during biological processes. Here we describe a method based on restriction enzymes and next-generation sequencing for identifying accessible DNA elements using a small amount of starting material, and use it to examine myeloid differentiation of primary human CD34+ cells. The accessibility of several classes of cis-regulatory elements was a predictive marker of in vivo DNA binding by transcription factors, and was associated with distinct patterns of histone posttranslational modifications. We also mapped large chromosomal domains with differential accessibility in progenitors and maturing cells. Accessibility became restricted during differentiation, correlating with a decreased number of expressed genes and loss of regulatory potential. Our data suggest that a permissive chromatin structure in multipotent cells is progressively and selectively closed during differentiation, and illustrate the use of our method for the identification of functional cis-regulatory elements

Comparison of Neck Skin Excision and Whole Carcass Rinse Sampling Methods for Microbiological Evaluation of Broiler Carcasses before and after Immersion Chilling

Sampling protocols for detecting Salmonella on poultry differ among various countries. In the United States, the U.S. Department of Agriculture Food Safety and Inspection Service dictates that whole broiler carcasses should be rinsed with 400 ml of 1% buffered peptone water, whereas in the European Union 25-g samples composed of neck skin from three carcasses are evaluated. The purpose of this study was to evaluate a whole carcass rinse (WCR) and a neck skin excision (NS) procedure for Salmonella and Escherichia coli isolation from the same broiler carcass. Carcasses were obtained from three broiler processing plants. The skin around the neck area was aseptically removed and bagged separately from the carcass, and microbiological analysis was performed. The corresponding carcass was bagged and a WCR sample was evaluated. No significant difference (alpha <= 0.05) in Salmonella prevalence was found between the samples processed by the two methods, but both procedures produced many false-negative Salmonella results. Prechill, 37% (66 carcasses), 28% (50 carcasses), and 51% (91 carcasses) of the 180 carcasses examined were positive for Salmonella by WCR, NS, and both procedures combined, respectively. Postchill, 3% (5 carcasses), 7% (12 carcasses), and 10% (17 carcasses) of the 177 carcasses examined were positive for Salmonella by the WCR, NS, and combination of both procedures, respectively. Prechill, E. coli plus coliform counts were 3.0 and 2.6 log CFU/ml by the WCR and NS methods, respectively. Postchill. E. coli plus coliform counts were 1.7 and 1.4 log CFU/ml by the WCR and NS methods, respectively