Coating of 1.4404 stainless steel by a combination of brazing and nitriding

In the current research, surface hardening of 1.4404 stainless steel was investigated. A hard Ni-containing coating was prepared by brazing at 1150 °C using a Ni foil with Si powder. The hardness behavior was increased by nitriding as well. The nitriding experiments were performed at low and high temperatures (460 and 640 °C) for a different period (3 and 6 h). The microstructure and material properties were characterized using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and Micro Vickers hardness testing. Results show that the hard phase and the binding Ni foil were well distributed into the hard layer. The hard coating material was composed of a Si-phases and Ni-containing compound dispersion. After the nitriding, the hardness of the samples was increased with increasing the nitriding time and temperature and increasing the brazing time. The 10 min brazing and 6h nitriding at 640°C resulted in 32% higher hardness than the non-nitride sample. Strong metallurgical bonding is formed between the stainless steel substrate and the coating layer, as well as between the binding Ni foil and the hard phase; because of the mutual diffusion of alloying elements, the hardness of this hard coating was 2 to 3 times higher than the initial hardness of steel substrate

Experimental Investigation of the Surface Roughness for Aluminum Alloy AA6061 in Milling Operation by Taguchi Method with the ANOVA Technique

The surface roughness of the machined parts is the most important parameter to predict the performance of mechanical components. Moreover, predicting the optimal machining parameters conditions is the preferable method for cost reduction and achieving the desired surface quality of the product. This study investigates three cutting parameters, such as depth of cut, spindle speed, and feed for the milling aluminium alloy AA6061, to predict the surface roughness quality. The experimental work utilized a manual milling machine with a coated carbide cutter. Furthermore, the experiments were arranged using the Taguchi L9 orthogonal array (OA) method. The average surface roughness (Ra) was measured and converted to signal-to-noise (S/N) ratio and then analyzed in the statistical method of analysis of variance (ANOVA). Finally, the optimal combination set speed, feed, and depth of cut was 2400 rpm, 30 mm/min, and 0.5 mm, respectively. Also, according to the ANOVA test, the most influential parameter was the spindle speed among the selected parameters, with the highest P value of (66.42%). In comparison, the lowest P value is a depth of cut (5.34%). Furthermore, spindle speed was the only significant factor statistically. By selecting a high spindle speed (2400 rpm), surface quality was enhanced, but the preferable level was low for depth of cut and feed.

Wettability of Metals by Water

The wetting behavior of water on metal surfaces is important for a wide range of industries, for example, in the metallurgical industry during the preparation of metallic nanoparticles or electrochemical or electroless coating preparation from aqueous solutions, as well as in the construction industry (e.g., self-cleaning metal surfaces) and in the oil industry, in the case of water–oil separation or corrosion problems. Wettability in water/metal systems has been investigated in the literature; nevertheless, contradictions can be found in the results. Some papers have reported perfect wettability even in water/noble metal systems, while other researchers state that water cannot spread well on the surface of metals, and the contact angle is predicted at around 60°. The purpose of this paper is to resolve this contradiction and find correlations to predict the contact angle for a variety of metals. In our research, the wetting behavior of distilled water on the freshly polished surface of Ag, Au, Cu, Fe, Nb, Ni, Sn, Ti, and W substrates was investigated by the sessile drop method. The contact angle of the water on the metal was determined by KSV software. The contact angle of water is identified as being between 50° and 80°. We found that the contact angle of water on metals decreases linearly with increasing the atomic radius of the substrate. Using our new equation, the contact angle of water was identified on all of the metals in the periodic table. From the measured contact angle values, the adhesion energy of the distilled water/metal substrate interface was also determined and a correlation with the free electron density parameter of substrates was determined

Herpes Simplex Virus 1 (HSV-1) ICP22 Protein Directly Interacts with Cyclin-Dependent Kinase (CDK)9 to Inhibit RNA Polymerase II Transcription Elongation

<div><p>The Herpes Simplex Virus 1 (HSV-1)-encoded ICP22 protein plays an important role in viral infection and affects expression of host cell genes. ICP22 is known to reduce the global level of serine (Ser)2 phosphorylation of the Tyr1Ser2Pro3Thr4Ser5Pro6Ser7 heptapeptide repeats comprising the carboxy-terminal domain (CTD) of the large subunit of RNA polymerase (pol) II. Accordingly, ICP22 is thought to associate with and inhibit the activity of the positive-transcription elongation factor b (P-TEFb) pol II CTD Ser2 kinase. We show here that ICP22 causes loss of CTD Ser2 phosphorylation from pol II engaged in transcription of protein-coding genes following ectopic expression in HeLa cells and that recombinant ICP22 interacts with the CDK9 subunit of recombinant P-TEFb. ICP22 also interacts with pol II <i>in vitro</i>. Residues 193 to 256 of ICP22 are sufficient for interaction with CDK9 and inhibition of pol II CTD Ser2 phosphorylation but do not interact with pol II. These results indicate that discrete regions of ICP22 interact with either CDK9 or pol II and that ICP22 interacts directly with CDK9 to inhibit expression of host cell genes.</p></div

Transient ectopic expression of ICP22 causes specific loss of pol II CTD Ser2 and Tyr1 phosphorylation.

<p>(<b>A</b>) Myc epitope-tagged ICP22 and U_S1.5 were ectopically expressed in HeLa cells from a transfected expression vector containing the ICP22 open-reading frame followed by three Myc epitope tags. pcDNA3 was used as the control in this and all subsequent transfections. An anti-Myc tag antibody was used for the western blot analysis and the positions of full-length ICP22 and U_S1.5 are noted. α-tubulin was used as a loading control (<b>B</b>) Western blot analysis was performed as described in (A). The antibody used is indicated on the right. (<b>C</b>) Western blot analysis was carried out using antibodies to the CTD phosphorylation marks indicated on the right. CTCF was used as a loading control.</p

Ectopic expression of ICP22 or the 193–256 subdomain causes loss of Ser2 phosphorylation from pol II transcribing host cell protein-coding genes.

<p>(<b>A</b>) Diagrams of the PLK2 and EIF2S3 genes, with the position of chromatin immunoprecipitation (ChIP) primer pairs indicated. (<b>B</b>), (<b>C</b>), (<b>E</b>) The results of ChIP analysis using the antibodies indicated on the left after transfection of vectors expressing the Myc-tagged proteins indicated. (<b>D</b>), (<b>F</b>) The ratio of the CTD modification to pol II as indicated at the left.</p

Sequence of primer sets used for qRT-PCR analysis.

<p>Sequence of primer sets used for qRT-PCR analysis.</p

Model for the role of ICP22 in inhibition of pol II CTD Ser2 phosphorylation.

<p>In uninfected cells (top panel), the negative elongation factor (NELF) and the DRB-sensitivity-inducing factor (DSIF) enhance pol II stalling. Subsequent recruitment of P-TEFb allows phosphorylation of DSIF, NELF and Ser2 of the pol II CTD, which leads to productive elongation. In the context of HSV-1-infected cells (bottom panel), ICP22 associates with P-TEFb and inhibits the kinase activity of CDK9 at the site of transcription, as indicated by the loss of phosphorylation of Ser2 of the pol II CTD, NELF and DSIF. As a consequence, the transition to productive elongation is inhibited. Interaction between ICP22 and pol II is not necessary to recruit ICP22 to genes or inhibit CDK9 when ICP22 is ectopically expressed in cells on its own. However, the interaction between pol II and ICP22 may be necessary to recruit ICP22 to host cell genes in HSV1-infected cells. Alternatively, interaction between ICP22 and pol II may play a role in regulation of viral gene expression by ICP22.</p

Ectopic expression of ICP22 or the 193–256 subdomain causes loss of pol II CTD Ser2 phosphorylation.

<p>Alignment of the conserved core motif within ICP22 of the alphaherpesviruses showing the degree of conservation according to the scheme above. Alignments were generated using PRALINE (<a href="http://www.ibi.vu.nl/programs/pralinewww/" target="_blank">http://www.ibi.vu.nl/programs/pralinewww/</a>). Asterisks indicate identical residues. Accession Nos. AEDO2597, AEV91400, AAA46092, CAA54262, AEL30878 (<b>B</b>) Top, diagram of full-length ICP22 and 193–256 showing the position of the alphaherpesvirus conserved core motif and the epiptope tags (Myc). Bottom, the results of western blot analysis of extracts from HeLa cells transfected with the constructs indicated using antibodies to the Myc tag. α-tubulin was used as a loading control. (<b>C</b>) Western blot analysis of whole-cell extract from HeLa cells transfected with the constructs indicated using antibodies to the Ser2P CTD phosphorylation mark. RPAP2 was used as a loading control.</p