Parametric study of the corrosion of API-5L-X65 QT steel using potentiostat based measurements in a flow loop

Low-carbon steel is widely used in industrial pipelines, and corrosion studies are focused mostly on erosion-corrosion, its prediction and control. In this paper, the corrosion rate in pipelines is modeled using a flow loop and measured by linear polarization resistance method (LPR) using a 3-electrode corrosion setup for API-5L-X65 QT steel. Optical microscopy and SEM studies are conducted to examine the surface of the sample and the corrosion products. The effect of NaCl concentration on the corrosion rate is studied at different pH, temperature range, and flow velocities with dissolved oxygen content in the solution maintained at 6 mg/L (6ppm). The corrosion rate is found to be varying from 1 mil per year (0.0254 mmyr−1) to 10 mils per year (0.254 mmyr−1), and the corrosion rate increases with the flow velocity and reaches a maximum at Reynolds Number above 10,000. Further increase in fluid velocity shows corrosion is flow insensitive, and uniform corrosion is predominant in the region

A Pan-cancer analysis reveals high-frequency genetic alterations in mediators of signaling by the tgf-β superfamily

We present an integromic analysis of gene alterations that modulate transforming growth factor β (TGF-β)-Smad-mediated signaling in 9,125 tumor samples across 33 cancer types in The Cancer Genome Atlas (TCGA). Focusing on genes that encode mediators and regulators of TGF-β signaling, we found at least one genomic alteration (mutation, homozygous deletion, or amplification) in 39% of samples, with highest frequencies in gastrointestinal cancers. We identified mutation hotspots in genes that encode TGF-β ligands (BMP5), receptors (TGFBR2, AVCR2A, and BMPR2), and Smads (SMAD2 and SMAD4). Alterations in the TGF-β superfamily correlated positively with expression of metastasis-associated genes and with decreased survival. Correlation analyses showed the contributions of mutation, amplification, deletion, DNA methylation, and miRNA expression to transcriptional activity of TGF-β signaling in each cancer type. This study provides a broad molecular perspective relevant for future functional and therapeutic studies of the diverse cancer pathways mediated by the TGF-β superfamily

An orthogonal DNA replication system for in vivo continuous directed evolution

Directed evolution is a powerful approach for engineering biomolecules and understanding the basic principles of adaptation. However, experimental strategies for directed evolution are notoriously labor-intensive and low-throughput, limiting access to demanding functions, multiple functions in parallel, and the study of molecular evolution in replicate. Here, I describe OrthoRep, an orthogonal DNA polymerase-plasmid pair in yeast that stably mutates ~100,000-fold faster than the host genome in vivo, exceeding the error threshold of genomic replication that causes single-generation extinction. User-defined genes in OrthoRep continuously and rapidly evolve through serial passaging, a highly straightforward and scalable process. Using OrthoRep, I evolved malarial DHFR to strongly resist the drug pyrimethamine in 90 independent replicates. This large-scale experiment revealed a more complex fitness landscape than previously realized, including new resistant alleles, common adaptive trajectories constrained by epistasis, rare outcomes that avoid a frequent early adaptive mutation, and a suboptimal fitness peak that occasionally traps evolving populations. OrthoRep enables a new paradigm of routine, high-throughput evolution of biomolecular and cellular function

Physical Optimization of Acid Fracturing with Unified Fracture Design

Acid fracturing is a reservoir stimulation technique where a fracture is created by injection of acid into the reservoir instead of conventional proppant slurry. The acid causes differential etching on the fracture walls, creating asperities. These asperities hold up the fracture wall, thus contributing to fracture conductivity. Acid fracturing is used mainly to stimulate carbonate rock. This technique has certain advantages over conventional fracturing. There is no proppant used, therefore the risk of screenout is nullified. There are also logistic reasons such as transport of proppant, which might make acid fracturing a viable choice. Theoretically, acid fractures have infinite conductivity in these conduits. This is not always true in practice. In this work, a physical optimization of acid fracturing is performed by utilizing the Unified Fracture Design methodology (UFD, hereforth). Parametric studies are performed to study the dependency of productivity on various factors.Chemical and Biomolecular Engineering, Department o

Tunable Expression Systems for Orthogonal DNA Replication

We recently developed an orthogonal DNA replication (OrthoRep) system capable of driving the rapid continuous evolution of genes in vivo. However, OrthoRep uses a special transcription system, the components of which (e.g., promoters) have previously limited the strength with which OrthoRep-encoded genes can be expressed. Here, we report a collection of synthetic and evolved OrthoRep expression parts that allow OrthoRep-encoded genes to span expression levels matching those of endogenous Saccharomyces cerevisiae genes. Specifically, we found that various promoter mutations as well as a genetically encoded poly(A) tail enable us to tune the expression level of OrthoRep-encoded genes over a large range and up to levels 43-fold higher than were previously attained, reaching at least ∼40% of the strength of the genomic TDH3 promoter. We further show that expression level gains using our new parts are stable over passaging and consistent across multiple genes and OrthoRep systems of different mutation rates. This new set of expression parts further expands OrthoRep's applicability to the continuous in vivo evolution of proteins and pathways

Effect of Magnetic Field on the Corrosion of API-5L-X65 Steel Using Electrochemical Methods in a Flow Loop

Limited studies have been conducted on the effect of a magnetic field on the corrosion behavior of steels. Investigating the effect on pipeline material in the oil and gas industries will be beneficial regarding corrosion prediction and control. In this work, the effect of a magnetic field on the corrosion process of API 5L X65 carbon steel was investigated in a well-developed flow loop using potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS). Using permanent magnets and a well-designed corrosion electrode set-up, the corrosion mechanism of API 5L X65 steel was studied at different magnetic orientations and different flow conditions in a NaCl solution. The surface morphology of the corroded samples was studied using a scanning electron microscope, and the micro-morphologies of the corrosion deposits and the surface elemental composition were analyzed. The results show that the presence of a magnetic field increases the corrosion rate of API 5L X65 carbon steel, and that flow velocities and magnetic orientation have a significant influence on the anodic corrosion current. The results of the polarization curves indicate a negative shift in the Tafel curve, leading to an increase in the corrosion rate with the introduction of a magnetic field in the flow system. The results of the EIS show that the charge transfer rate is decreased when a magnetic field is applied. This work provides important direction in terms of the understanding of the combined effect of magnetism and flow on the corrosion in pipelines used in the oil and gas industries

Magnetic resonance imaging diagnosis of Mayer-Rokitansky-Kuster-Hauser syndrome

Magnetic resonance imaging (MRI) is the mainstay in the imaging evaluation of Mullerian agenesis, but is not routinely being utilized, particularly in India. Though sagittal MRI clearly demonstrates the absence or hypoplasia of the uterus and the axial images demonstrate the normal ovaries, it is the ability to identify and objectively evaluate other associated anomalies that makes MRI a unique diagnostic modality. It is also noninvasive and has multiplanar capabilities at the same time having a very high soft tissue resolution. We presume it can be used as a comprehensive imaging package for evaluating these patients at one sitting. We report a case of Mullarian agenesis presenting as primary amenorrhea stressing the role and benefits of MRI