scholarly journals A review of fungal influenced corrosion of metals

2021 ◽  
Vol 62 (4) ◽  
pp. 333-339
Author(s):  
Imo Okorie ◽  
Romanus Nwokorie

The growth of fungi on the surface of metals has great influence on their structural integrity and failure. Their growth on metal surfaces is determined by their secreted metabolites which enable them to adapt to new environmental and nourishment conditions. Although information on the capacity of fungi to adapt to metal surfaces is scarce, most fungi growing on metal surfaces alter the composition of the metals involving it in the process of functional growth and metabolism. Changes in the composition and colour of the metals are some of the evidences confirming that fungus has penetrated the metal surfaces and use it to satisfy its nutritional need with resultant corrosion. In this work we tried to explain different mechanisms of fungal influenced corrosion from different perspectives ranging from the role of biofilms, corrosive media generation by fungal metabolism processes to electrochemical processes generated by fungal growth on metal surfaces. Finally, no single mechanism can conclusively explain all forms of fungal influenced corrosion because every mechanism is unique and applies to individual fungus, its metabolic biproducts or the growth pattern.

2019 ◽  
Vol 118 (11) ◽  
pp. 80-88
Author(s):  
Ramyar Rzgar Ahmed ◽  
Hawkar Qasim Birdawod ◽  
S. Rabiyathul Basariya

The study dealt with tax evasion in the medical profession, where the problem was the existence of many cases of tax evasion, especially tax evasion in the income tax of medical professions. The aim of the study is to try to shed light on the phenomenon of tax evasion and the role of the tax authority in the development of controls and means that reduce the phenomenon of tax evasion. The most important results of the low level of tax awareness and lack of knowledge of the tax law and the unwillingness to read it and the sense of taxpayers unfairness of the tax all lead to an increase in cases of tax evasion and in suggested tightening control and follow-up on the offices of auditors, through the investigation and auditing The reports of certified accountants and the use of computers for this purpose in order to raise the degree of confidence in these reports and bring them closer to the required truth and coordination and cooperation with the Union of Accountants and Auditors and inform them about each case of violations of the auditors and accountants N because of its great influence in the rejection of the organization of the accounts and not to ratify fake accounts lead to show taxpayers accounts on a non-truth in order to tax evasion.


2019 ◽  
Vol 118 (1) ◽  
pp. 57-64
Author(s):  
G. Aiswarya ◽  
Dr. Jayasree Krishnan

Traditionally the products were pushed into the hands of customers by production and selling strategies; then the marketing strategy evolved which gained momentum by understanding the customer needs and developing products satisfying those needs. This strategy is most prevalent and what should be done to stand up in this most competitive scenario? The answer to this key question is to create an experience. The customers now also seek good experiences than other benefits. Brand experience has gained more attention, especially fashion brands. Previous studies demonstrate the role of the brand experience in brand equity and other consumer behavior constructs. But very little is known about the impact of brand experiences on fashion brands. The aim of this study is to develop a model which makes our understanding better about the role of Brand preference and Brand experience and its influence on purchase intention of the brand. An initial exploratory study is conducted using a focus group to generate items for the study. The items, thus generated are prepared in the form of a questionnaire and samples were collected.  Exploratory factor analysis is conducted and the reliability of the constructs is determined. These constructs are loaded onto AMOS to perform Confirmatory factor analysis. The results confirmed the scales used. We also noticed that Brand preference has a great influence on the Brand experience. Thereby the finding supports the role of the brand experience which tends to have a mediating role in influencing the purchase intention.


Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 562
Author(s):  
Miliça Ristovski ◽  
Danny Farhat ◽  
Shelly Ellaine M. Bancud ◽  
Jyh-Yeuan Lee

Lipid composition in cellular membranes plays an important role in maintaining the structural integrity of cells and in regulating cellular signaling that controls functions of both membrane-anchored and cytoplasmic proteins. ATP-dependent ABC and P4-ATPase lipid transporters, two integral membrane proteins, are known to contribute to lipid translocation across the lipid bilayers on the cellular membranes. In this review, we will highlight current knowledge about the role of cholesterol and phospholipids of cellular membranes in regulating cell signaling and how lipid transporters participate this process.


2021 ◽  
Vol 22 (5) ◽  
pp. 2435
Author(s):  
Marzia Beccaccioli ◽  
Manuel Salustri ◽  
Valeria Scala ◽  
Matteo Ludovici ◽  
Andrea Cacciotti ◽  
...  

Fusarium verticillioides causes multiple diseases of Zea mays (maize) including ear and seedling rots, contaminates seeds and seed products worldwide with toxic chemicals called fumonisins. The role of fumonisins in disease is unclear because, although they are not required for ear rot, they are required for seedling diseases. Disease symptoms may be due to the ability of fumonisins to inhibit ceramide synthase activity, the expected cause of lipids (fatty acids, oxylipins, and sphingolipids) alteration in infected plants. In this study, we explored the impact of fumonisins on fatty acid, oxylipin, and sphingolipid levels in planta and how these changes affect F. verticillioides growth in maize. The identity and levels of principal fatty acids, oxylipins, and over 50 sphingolipids were evaluated by chromatography followed by mass spectrometry in maize infected with an F. verticillioides fumonisin-producing wild-type strain and a fumonisin-deficient mutant, after different periods of growth. Plant hormones associated with defense responses, i.e., salicylic and jasmonic acid, were also evaluated. We suggest that fumonisins produced by F. verticillioides alter maize lipid metabolism, which help switch fungal growth from a relatively harmless endophyte to a destructive necrotroph.


2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
A.J Francis ◽  
J.M Firth ◽  
N Islam ◽  
J Gorelik ◽  
K.T MacLeod

Abstract Background Post-menopausal women have an enhanced risk of developing heart failure, attributed to declining oestrogen levels during menopause. However, the signalling mechanisms remain undetermined. Purpose We aim to determine the role of G-protein coupled oestrogenic receptor 1 (GPER1) in intracellular Ca2+ regulation and the consequences of hormonal changes that may exacerbate the pathophysiology of heart failure. Methods Ovariectomy (OVx) (mimics menopausal hormone changes) or sham surgeries were conducted on female guinea pigs. Left ventricular cardiomyocytes were isolated 150-days post-operatively for experimental use. Cellular t-tubule network and structural integrity was measured using fluorescent di-8-ANEPPs staining and scanning ion conductance microscopy. GPER1 expression and localisation was measured by Western blot and immunostaining. The role of GPER1 activation was measured using selective agonist G-1 in electrophysiological and Ca2+-sensitive dye fluorescence experiments. Results Following oestrogen withdrawal, the t-tubule network density decreased by 13% and z-groove index reduced by 15%. GPER1 predominantly localised to the peri-nuclear endoplasmic reticulum and its expression increased by 32% in OVx. Action potential duration (APD) prolonged in OVx and following GPER1 activation, APD90 shortened by 11% and 25% in sham and OVx respectively. OVx cells had larger peak inward Ca2+ current (ICaL) (by 22%) and sarcoplasmic reticulum (SR) Ca2+ content (by 13%), compared with sham. While GPER1 activation had little effect on peak ICaL or SR content, it reduced Ca2+ transient amplitude (by 20%), SR fractional release (by 11%) in OVx cells. The frequency of occurrence of spontaneous Ca2+ waves evoked by periods of rapid stimulation reduced by 40% and wave-free survival time prolonged in OVx cells following GPER1 activation. Conclusions In the hearts of an animal species whose electrophysiology and intracellular Ca2+ regulation is akin to humans, we show that following oestrogen deficiency, the t-tubule network is down-regulated and becomes disorganised, GPER1 expression is increased and its activation induces negative inotropic responses in cardiomyocytes. This may limit the adverse changes to Ca2+ signalling reported in OVx that could be pro-arrhythmic and exacerbate the progression to heart failure. Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): British Heart Foundation


Author(s):  
Changyu Zhou ◽  
Bo Wang ◽  
Zhigang Sun ◽  
Jilin Xue ◽  
Xiaohua He

High temperature pressure pipes are widely used in power stations, nuclear power plants, and petroleum refinery, which always bear combined effects of high temperature, high pressure, and corrosive media, so the local pits are the most common volume defects in pressure pipe. Due to various reasons, the defects usually appear on the internal or external wall of pipe. In this paper, the dimensions of a defect were characterized as three dimensionless factors: relative depth, relative gradient and relative length. The main objects of study were the pipe with an internal pit and pipe with an external pit. Orthogonal array testing of three factors at four different levels was applied to analyze the sequence of the influence of three parameters. In present study, when the maximum principal strain nearby the location of the defects reaches 2%, the corresponding load is defined as the limit load, which is classified as two kinds of load type: limit pressure and limit bending moment. According to this strain criterion and isochronous stress strain data of P91 steel, the limit load of high temperature pipe with a local pit was determined by using ABAQUS. And in the same load condition of the pipe with the same dimensionless factors, the limit load of the internal defected pipe was compared with that of the external defected pipe. The results of this study can provide a reference for safety assessment and structural integrity analysis of high temperature creep pressure pipe with pit defects.


2006 ◽  
Vol 50 (8) ◽  
pp. 2797-2805 ◽  
Author(s):  
Jingsong Zhu ◽  
Paul W. Luther ◽  
Qixin Leng ◽  
A. James Mixson

ABSTRACT A family of histidine-rich peptides, histatins, is secreted by the parotid gland in mammals and exhibits marked inhibitory activity against a number of Candida species. We were particularly interested in the mechanism by which histidine-rich peptides inhibit fungal growth, because our laboratory has synthesized a variety of such peptides for drug and nucleic acid delivery. In contrast to naturally occurring peptides that are linear, peptides made on synthesizers can be varied with respect to their degrees of branching. Using this technology, we explored whether histidine-lysine (HK) polymers of different complexities and degrees of branching affect the growth of several species of Candida. Polymers with higher degrees of branching were progressively more effective against Candida albicans, with the four-branched polymer, H2K4b, most effective. Furthermore, H2K4b accumulated efficiently in C. albicans, which may indicate its ability to transport other antifungal agents intracellularly. Although H2K4b had greater antifungal activity than histatin 5, their mechanisms were similar. Toxicity in C. albicans induced by histatin 5 or branched HK peptides was markedly reduced by 4,4′-diisothiocyanato-stilbene-2,2′-disulfonate, an inhibitor of anion channels. We also determined that bafilomycin A1, an inhibitor of endosomal acidification, significantly decreased the antifungal activity of H2K4b. This suggests that the pH-buffering and subsequent endosomal-disrupting properties of histidine-rich peptides have a role in their antifungal activity. Moreover, the ability of the histidine component of these peptides to disrupt endosomes, which allows their escape from the lysosomal pathway, may explain why these peptides are both effective antifungal agents and nucleic acid delivery carriers.


2009 ◽  
Vol 185 (3) ◽  
pp. 475-491 ◽  
Author(s):  
Evgeny Onischenko ◽  
Leslie H. Stanton ◽  
Alexis S. Madrid ◽  
Thomas Kieselbach ◽  
Karsten Weis

The nuclear pore complex (NPC) mediates all nucleocytoplasmic transport, yet its structure and biogenesis remain poorly understood. In this study, we have functionally characterized interaction partners of the yeast transmembrane nucleoporin Ndc1. Ndc1 forms a distinct complex with the transmembrane proteins Pom152 and Pom34 and two alternative complexes with the soluble nucleoporins Nup53 and Nup59, which in turn bind to Nup170 and Nup157. The transmembrane and soluble Ndc1-binding partners have redundant functions at the NPC, and disruption of both groups of interactions causes defects in Ndc1 targeting and in NPC structure accompanied by significant pore dilation. Using photoconvertible fluorescent protein fusions, we further show that the depletion of Pom34 in cells that lack NUP53 and NUP59 blocks new NPC assembly and leads to the reversible accumulation of newly made nucleoporins in cytoplasmic foci. Therefore, Ndc1 together with its interaction partners are collectively essential for the biosynthesis and structural integrity of yeast NPCs.


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