Electron Microscopy Studies Research Articles

Characterization of the Structural Requirements for the NADase Activity of Bacterial Toll/IL-1R domains in a Course-based Undergraduate Research Experience.

TLRs initiate innate immune signaling pathways via Toll/IL-1R (TIR) domains on their cytoplasmic tails. Various bacterial species also express TIR domain-containing proteins that contribute to bacterial evasion of the innate immune system. Bacterial TIR domains, along with the mammalian sterile α and TIR motif-containing protein 1 and TIRs from plants, also have been found to exhibit NADase activity. Initial X-ray crystallographic studies of the bacterial TIR from Acinetobacter baumannii provided insight into bacterial TIR structure but were unsuccessful in cocrystallization with the NAD+ ligand, leading to further questions about the TIR NAD binding site. In this study, we designed a Course-Based Undergraduate Research Experience (CURE) involving 16-20 students per year to identify amino acids crucial for NADase activity of A. baumannii TIR domain protein and the TIR from Escherichia coli (TIR domain-containing protein C). Students used structural data to identify amino acids that they hypothesized would play a role in TIR NADase activity, and created plasmids to express mutated TIRs through site-directed mutagenesis. Mutant TIRs were expressed, purified, and tested for NADase activity. The results from these studies provide evidence for a conformational change upon NAD binding, as was predicted by recent cryogenic electron microscopy and hydrogen-deuterium exchange mass spectrometry studies. Along with corroborating recent characterization of TIR NADases that could contribute to drug development for diseases associated with dysregulated TIR activity, this work also highlights the value of CURE-based projects for inclusion of a diverse group of students in authentic research experiences.

Externally supplied ascorbic acid moderates detrimental effects of UV-C exposure in cyanobacteria.

The defensive role performed by exogenously supplied ascorbic acid in the cyanobacterium Nostoc muscorum Meg1 against damages produced by UV-C radiation exposure was assessed in this study. Exposure to UV-C (24mJ/cm2) significantly enhanced reactive oxygen species (ROS) (50%) along with peroxidation of lipids (21%) and protein oxidation (22%) in the organism. But, addition of 0.5mM ascorbic acid prior to UV-C exposure showed reduction in ROS production (1.7%) and damages to lipids and proteins (1.5 and 2%, respectively). Light and transmission electron microscopic studies revealed that ascorbic acid not only protected filament breakage but also restricted severe ultrastructural changes and cellular damages in the organism. Although the growth of the organism was repressed up to 9% under UV-C treatment within 15days, a pre-treatment with ascorbic acid led to growth enhancement by 42% in the same period. Various growth parameters such as photo-absorbing pigments (phycoerythrin, phycocyanin, allophycocyanin, chlorophyll a, and carotenoids), water splitting complex (WSC), D1 protein, RuBisCO, glutamine synthetase and nitrogenase activities in the UV-C treated organism were seen to be relatively intact in the presence of ascorbic acid. Thus, a detailed analysis undertaken in the present study was able to demonstrate that ascorbic acid not only act as first responder against harmful UV-C radiation by down-regulating ROS production, it also accelerated the growth performance in the organism in the post UV-C incubation period as an immediate response to an adverse experience presented in the form of UV-C radiation exposure.

Dielectric properties and microstructure of BaTiO3-PTFE composites via cold sintering process

The cold sintering process is capable of densifying ceramics and metal powders with other phases into composite materials without inducing chemical reactions between the constituent phases or causing the decomposition of any phases. In this study, we considered the co-sintering of BaTiO3 powders with polytetrafluoroethylene (PTFE) in the grain boundaries. We examined the microstructure and dielectric properties of these composites with different volume fractions of PTFE. The composites were highly dispersive from microstructure and general mixing laws, due to using fine PTFE. Transmission electron microscopy studies demonstrated that the thickness of the PTFE in the grain boundaries was determined with different volume fractions of PTFE. The cold-sintered BaTiO3 composites had high volume resistivity (>1011 Ω·cm), enhancing the resistivity of the cold-sintered pure BaTiO3 using Ba(OH)2·8H2O transient phase. Reliability tests, such as breakdown strength, and Jt curves, were conducted, and the reliability was improved by using fine powders of PTFE with controlled mixing.

Slurry infiltrated low-quality construction and demolition coarse aggregate waste in concrete – a sustainable construction

Exponential growth in infrastructure projects, stimulated by emerging sophisticated technologies have been instrumental in the salutary proliferation of the construction sector, globally. An indubitable adversity of the rapid boom in the construction industry has been the rampant cumulative fallout of burgeoning waste during the demolition and construction phases of restoration. The current study explored the propriety of replacing natural coarse aggregate by low-quality recycled coarse aggregates (RCA) with varying proportions, along with silica fume (SF) and polypropylene (PP) fibers as admixtures, for the preparation of concrete. As the quality of RCA is determined by the history of its parent demolished structure, this investigation was preceded by assessment of the properties of RCA. A statistical approach using design of experiments, adopted to determine the coherent combinations of RCA and admixtures, yielded 16 combinations. Accordingly, concrete specimens were prepared with various quantities of RCA in place of natural coarse aggregate. Optimum proportions of the ingredients were inferred, based on the compressive strength attained by the concrete specimens. Further strength property evaluation was conducted, using these low-quality RCA treated with cement and silica fume slurry. Based on the strength results, 75% slurry infiltrated RCA, coupled with 10% SF and 0.5% PP, provided better strength in compression, tension and flexure. Scanning electron microscopy study, adopted for characterization of the micro-structural slurry-infiltrated RCA, shows the presence of strong interfacial transition zone in the treated RCA concrete. Thus, this study confirmed the efficacy of low-quality RCA as a promising material for structural construction, concurrent with a solution to various ecological disruptions precipitated by infrastructure construction and demolition wastes.

Resveratrol ameliorates atrazine-induced caspase-dependent apoptosis and fibrosis in the testis of adult albino rats

Pesticides like atrazine which are frequently present in everyday surroundings, have adverse impacts on human health and may contribute to male infertility. The work aimed to analyze the histological and biochemical effects of atrazine on the testis in adult albino rats and whether co-administration with resveratrol could reverse the effect of atrazine. Forty adult male albino rats in good health participated in this study. They were categorized at random into four groups: the Group Ӏ received water through a gastric tube for two months every day, the Group ӀӀ received resveratrol (20 mg/kg body weight (b.w.)) through a gastric tube for two months every day, the Group ӀӀӀ received atrazine (50 mg/kg bw) through a gastric tube for two months every day, the Group ӀV received concomitant doses of atrazine and resveratrol for two months every day. The testes of the animals were then carefully removed and prepared for biochemical, immunohistochemical, light, and electron microscopic studies. Atrazine exposure led to a significant decrease in serum testosterone hormone level, upregulation of caspase 3 and iNOS mRNA levels, destructed seminiferous tubules with few sperms in their lumens, many collagen fibres accumulation in the tunica albuginea and the interstitium, abnormal morphology of some sperms as well as many vacuolations, and damaged mitochondria in the cytoplasm of many germ cells. Concomitant administration of resveratrol can improve these adverse effects. It was concluded that atrazine exposure is toxic to the testis and impairs male fertility in adult rat and coadministration of resveratrol guards against this toxicity.

Nucleation, crystal growth, XRD, optical, electrical, PC, SEM, SHG and Z-scan analysis of LHPP for NLO and optical limiting application

High-quality organic L-histidinium 4-nitrophenolate 4-nitrophenol (LHPP) single crystals were grown using an aqueous solution. The crystals were grown using slow evaporation solution technique (SEST) at a temperature of 40°C using a constant temperature bath (CTB). Nucleation growth rates were monitored for various durations using an optical microscope. The crystalline perfection was confirmed through sharp, high-intensity diffraction peaks observed in the theoretical and experimental powder X-ray diffraction (PXRD) analysis, which also confirmed the monoclinic crystal structure with the noncentrosymmetric P21 space group. The crystallite size and strain were calculated using Williamson–Hall coefficient. Vibrational frequency assignments of LHPP were determined using FTIR spectroscopic analysis. Optical properties were studied using UV–Vis NIR spectroscopic studies, which showed that the crystals have very low absorption and high transmittance in the entire visible region. Additionally, the optical energy bandgap (Eg) was calculated and found to be 6.15[Formula: see text]eV. Luminescence properties were studied using fluorescence (FL) analysis. Dielectric investigations were subjected to varying frequencies to study the suitability of the crystal for transistor application. The positive photoconductive (PC) nature of the crystal was confirmed using photoconductivity studies to confirm suitability for photodetector devices that measure the intensity of light rays. Etching studies revealed the growth pattern and the formation of different kinds of etch pits. The surface morphology was studied using scanning electron microscopy (SEM) and electrochemical studies were also carried out. The relative second harmonic generation (SHG) efficiency of the material was also examined and found to be 1.34 times that of standard KDP. The optical limiting and higher-order nonlinear optical (NLO) properties of the grown crystals were studied by the [Formula: see text]-scan method using a Nd: YAG laser functioning at 532[Formula: see text]nm.

Revealing the displacive and diffusional phase transformations in a low-modulus Ti-12Nb alloy

Non-toxic and biocompatible Ti alloys with low modulus are promising biomaterials for implants. Except from the intensely studied metastable β Ti-Nb-based alloys, the α′-type Ti alloys could also present low modulus. But due to the low β stability, the microstructures of these α′ Ti alloys are sensitive to the heat-treatments especially to the cooling rates, which could lead to very different deformation mechanisms and mechanical properties. Thus, the phase transformations and the ‘microstructure–mechanical property’ correlation in the α′ Ti alloys need to be established. In this study, a novel Ti-12Nb wt% alloy was prepared and cooled from the β region temperature to obtain the water-quenched (WQ), air-cooled (AC), and furnace-cooled (FC) samples. Systematic investigations revealed the displacive β → α′ martensitic transformation in the WQ and diffusional β → β + α transformation in the AC and FC samples, in which the α′/α show evident variant selections. The inter-variant orientation relationships (ORs) among the α′/α variants and their ORs with the retained β phase, were found to be agree well with the classical Burgers OR. The high-resolution transmission electron microscope (HRTEM) studies show coherent α′/α′ interfaces in the WQ samples and α/β phase boundaries in the AC and FC samples, the abnormal β nanodomains inside the α′ martensites in WQ samples and the ω nanoparticles in the β phase of AC and FC samples were also presented. The tensile tests show increasing Young's modulus of 61.8 GPa, 77.1 GPa and 108.6GPa in the WQ, AC and FC samples, respectively. The difference in the modulus of these samples was explained by the Nb dependency of Young's modulus in the Ti-Nb alloy. The correlations between the microstructures, deformation mechanisms and mechanical properties were established. The {101¯1}α′ and {101¯2}α′ deformation twins inside the α′ martensites are believed to contribute to the good plasticity in the WQ samples, while the fine α + β structures and severely piled-up dislocations should account for the high yield strength and the poor plasticity in the AC samples. The abundant mobile dislocations in the α bands and deformation-induced ω needles in the surrounding β phase led to the best plasticity in the FC samples among all Ti-12Nb samples. This study systematically studied the displacive and diffusional transformations and the plastic deformation in a Ti-12Nb alloy, the results might pave the way for designing low-modulus biomedical α′ Ti alloy with low content of β stabilizing elements and provide insights into tailoring of the phase transformations and mechanical properties in these Ti alloys.

In vitro antifungal activity analysis of Streptomyces sp. strain 196 against Candida albicans and Aspergillus flavus.

Numerous bioactive compounds have been reported to be produced by the members of the genus Streptomyces. During our previous studies, Streptomyces sp. strain 196 was tested for its antimicrobial activity, and bioactive compounds produced by this strain were characterized LC-MS and 1H NMR. To examine the antifungal potential of strain 196 is the goal of the current investigation. Present investigation is focused on exploring antifungal activity of extract of strain 196 (196EA) on membrane disruption potential against two fungi Candida albicans ATCC 90028 and Aspergillus flavus ITCC 5599. Results revealed that the MIC value is higher for A. flavus than for C. albicans which is 450µg/mL and 250µg/mL, respectively. Disc diffusion and spot assay also correspond to the values of the MIC for their respective pathogen. In growth curve analysis, lag and log phase are significantly affected by the extract of strain 196. The effects of extract from strain 196 on plasma membrane disruption of Candida albicans and Aspergillus flavus were analyzed in terms of ergosterol quantification assay, cellular leakage, proton efflux measurement (PM-ATPase), plasma membrane integrity assay (PI), and DNA damage assay (DAPI). Results shown that the extract of strain 196 has the potential to inhibit the cell membrane of the both pathogenic fungi which was further confirmed with the help of scanning electron microscopic (SEM) studies.

Enhancing rooting tobacco (Nicotiana tabacum) plant by loaded indole-3-butyric acid in alginate/chitosan nanocapsule.

Recently, nanocarriers have been utilized for encapsulating and sustained release of agrochemicals specifically auxins. Due to their potential applications such as increased bioavailability and improved crop yield and nutritional quality. Herein, the efficacy of alginate/chitosan nanocapsules as a nanocarrier for the hormone indole-3-butyric acid (IBA) loading and its effect on rooting tobacco plants has been carried out in the present study. The average particle size of IBA-alginate/chitosan nanocapsules was measured by Dynamic light scattering analysis at 321 nm. Scanning electron microscope studies revealed the spherical shape of nanoparticles with an average size of 97 nm. The average particle size of IBA-alginate/chitosan nanocapsules was measured by Dynamic light scattering analysis at 321 nm. The characteristic peaks of IBA on alginate/chitosan nanocapsules were identified by Fourier transform infrared spectroscopic analysis. Also, high efficiency (35%) of IBA hormone loading was observed. The findings indicated that the concentration of 3 mgL-1 of IBA-alginate/chitosan nanocapsules has the highest efficiency in increasing the rooting in tobacco (Nicotiana tabacum) plants compared to other treatments. According to our results, we can introduce alginate/chitosan nanocapsules as an efficient nanocarrier in IBA hormone transfer applications and their use in agriculture.

Sustainable Electrosynthesis of N,N-Dimethylformamide via Relay Catalysis on Synergistic Active Sites.

Electrified synthesis of high-value organonitrogen chemicals from low-cost carbon- and nitrogen-based feedstocks offers an economically and environmentally appealing alternative to traditional thermocatalytic methods. However, the intricate electrochemical reactions at electrode surfaces pose significant challenges in controlling selectivity and activity, especially for producing complex substances such as N,N-dimethylformamide (DMF). Herein, we tackle this challenge by developing relay catalysis for efficient DMF production using a composite WO2-NiOOH/Ni catalyst with two distinctive active sites. Specifically, WO2 selectively promotes dimethylamine (DMA) electrooxidation to produce strongly surface-bound (CH3)2N*, while nearby NiOOH facilitates methanol electrooxidation to yield more weakly bound *CHO. The disparity in binding energetics of the key C- and N-intermediates expedites C-N coupling at the WO2-NiOOH interface. In situ infrared spectroscopy with isotope-labeling experiments, quasi-in situ electron paramagnetic resonance trapping experiments, and electrochemical operating experiments revealed the C-N coupling mechanism and enhanced DMF-synthesis selectivity and activity. In situ X-ray absorption spectroscopy (XAS) and postreaction transmission electron microscopy (TEM) studies verified the stability of WO2-NiOOH/Ni during extended electrochemical operation. A Faradaic efficiency of ∼50% and a production rate of 438 μmol cm-2 h-1 were achieved at an industrially relevant current density of 100 mA cm-2 over an 80 h DMF production period. This study introduces a new paradigm for developing electrothermo relay catalysis for the sustainable and efficient synthesis of valuable organic chemicals with industrial potential.

Greening the composite industry: Evaluating Lantana camara Verbenaceae fiber as a promising substitute for lightweight polymer matrix composites

Presently, researchers are engaged in investigations with the aim of developing novel products that exhibit biodegradability and subsequent environmental friendliness. As products, biofiber-based composites are gaining popularity in various industries. Consequently, this investigation successfully identified a unique cellulosic stem fiber from Lantana camara L. (Verbenaceae) plant. As the fiber was unique, sustainable, and abundantly available throughout all seasons, it was selected for the comprehensive characterization investigation to find its potential use as a lightweight bio-based composite material substitute for synthetic fibers. Physiochemical examination revealed that the Lantana camara Verbenaceae fiber had a greater cellulose concentration (61.23±8.42 %) and density (1167±60 kg/m3), measured to be very less compared to synthetic fiber, making a perfect choice for producing lightweight composites with higher strength. The presence of cellulose Iβ and the ordered character of the crystallites were verified by Fourier transform infrared spectroscopy and X-ray diffraction method. Thermogravimetric study showed the maximum degradation temperature of 323 °C, a thermal stability of 242 °C, and a kinetic activation energy of 66.11 kJ/mol. The maximum tensile strength, strain-to-failure percent, and Young’s modulus were observed for 50-mm-length fibers. Detailed analysis of the longitudinal section of the fiber from atomic force microscopy and scanning electron microscopy study revealed that the fiber had a rough surface, which improves the bonding behavior when reinforced. The aforementioned properties showed that L. camara L. fibers are an excellent, greener alternative reinforcement for composite materials, allowing for the cleaner, more sustainable components.

Transmission Electron Microscopy Study of a Nanosuspension of Verteporfin and Evaluation of Stability in Human Serum

Transmission Electron Microscopy Study of a Nanosuspension of Verteporfin and Evaluation of Stability in Human Serum

Identical Location Electron Microscopy Study of Cu Electrocatalyst

Identical Location Electron Microscopy Study of Cu Electrocatalyst

A non-toxic equinatoxin-II reveals the dynamics and distribution of sphingomyelin in the cytosolic leaflet of the plasma membrane

Sphingomyelin (SM) is a major sphingolipid in mammalian cells. SM is enriched in the extracellular leaflet of the plasma membrane (PM). Besides this localization, recent electron microscopic and biochemical studies suggest the presence of SM in the cytosolic leaflet of the PM. In the present study, we generated a non-toxic SM-binding variant (NT-EqtII) based on equinatoxin-II (EqtII) from the sea anemone Actinia equina, and examined the dynamics of SM in the cytosolic leaflet of living cell PMs. NT-EqtII with two point mutations (Leu26Ala and Pro81Ala) had essentially the same specificity and affinity to SM as wild-type EqtII. NT-EqtII expressed in the cytosol was recruited to the PM in various cell lines. Super-resolution microscopic observation revealed that NT-EqtII formed tiny domains that were significantly colocalized with cholesterol and N-terminal Lyn. Meanwhile, single molecule observation at high resolutions down to 1 ms revealed that all the examined lipid probes including NT-EqtII underwent apparent fast simple Brownian diffusion, exhibiting that SM and other lipids in the cytosolic leaflet rapidly moved in and out of domains. Thus, the novel SM-binding probe demonstrated the presence of the raft-like domain in the cytosolic leaflet of living cell PMs.

Effect of Two Forms of Tenofovir on Duodenal Enterocytes - a Hypothesis for Different Effect of TDF and TAF on Body Weight and Plasma Lipids.

Tenofovir disoproxil fumarate (TDF) compared to tenofovir alafenamide (TAF) leads to lower body weight and plasma lipids by an unknown mechanism. We hypothesize that TDF, when absorbed, may damage enterocytes of the proximal duodenum, leading to reduced absorption of nutrients. People living with HIV, without significant gastrointestinal symptoms, receiving TDF (n=12) or TAF (n=12) containing regimen underwent esophagogastroduodenoscopies with duodenal biopsies. Plasma/serum concentrations of nutrients absorbed from proximal duodenum and serum intestinal fatty-acid-binding protein (I-FABP), a marker of enterocyte damage, were measured. COX/SDH histochemical staining and electron microscopy (EM) were conducted to evaluate mitochondria. Five patients in TDF (celiac disease (excluded from further analyses), helicobacter gastritis, and three esophagitis) and two in TAF group (two esophagitis) had a pathological finding in esophagogastroduodenoscopy. Villi were flatter (337 (59) vs. 397 (42) μm, p=0.016), crypts non-significantly deeper (200 (46) vs. 176 (27) μm, p=0.2), and villus to crypt ratio lower (1.5 (0.42) vs. 2.5 (0.51), p=0.009) in TDF vs. TAF group. I-FABP concentration was higher in TDF vs. TAF group (3.0 (1.07) vs. 1.8 (0.53) ng/ml, p=0.003). TDF group had numerically but not statistically significantly lower concentrations of folate, vitamins A, B1, D, and E. COX/SDH staining showed signs of mitochondrial damage in 10 participants in TDF and 11 in TAF group. EM studies showed similar mitochondrial damage in both groups. Duodenal villous alterations may explain TDF-associated decrease in body weight and plasma lipids. Larger studies are needed to evaluate concentrations of nutrients absorbed from duodenum among TDF users.

Synthesis and properties of new polyimide foams from foaming compositions with flexible segments of aliphatic diamine

AbstractNew foaming prepolymer compositions based on 4,4′‐oxydiphthalic anhydride, 4,4′‐diaminodiphenyl ether, 1,6‐hexamethylenediamine (HMDA), and a surfactant were synthesized. Polyimide (PI) foams containing from 0 to 40 mol% HMDA were prepared. The possibility of controlling the pore sizes in a foam material by selecting different fractions (250–400 μm) of particles of the powdered foam composition for heat treatment was shown. Scanning electron microscopy studies of morphology of the synthesized PI foams (PIFs) showed that all foams exhibited open cellular structures with pore diameters ranging from 50 to 500 μm. The influence of the components of the foaming composition (surfactant and aliphatic diamine) on the structure, thermal, and mechanical properties of the resulting PIFs was traced. The samples of PIFs containing 20% and 30% HMDA were elastic (the corresponding stress–strain curves were almost linear up to the 30% deformation) and able to restore their shape after removing the load. The resulting foams exhibited high thermal stability (the onset of weight loss was observed in the 470–500°C range). It was revealed that the synthesized PIF compositions were incombustible in an open flame. Due to their high heat resistance and nonflammability, the obtained PIFs can be used for thermal insulation applications in the aerospace, transport, construction, and microelectronics industries.Highlights New, lightweight, flexible, and nonflammable PIFs have been synthesized. The HMDA additive imparts elasticity to PIFs. The introduction of a surfactant (KT‐6) makes the PIF homogeneous.

Hexagonal rod-like Eu3+doped CaMoO4 phosphors: Structural, photoluminescence and photometric properties for display device applications

A multicolored LED illumination device is a compact, durable, easy to obtain color-adjustable output illumination source. It is frequently utilized in the domains of room illumination and exterior displays. However, the advancement of multicolor LEDs has been hampered by the rise in price and the fall in luminous efficacy while changing illumination colors. In the present investigation we have prepared intense red emitting Eu3+ doped CaMoO4 phosphor nanopowders via simple solid-state reaction technique. The powder X-ray diffraction (PXRD) studies reveal the crystalline nature of the samples with scheelite–type mono phase tetragonal structure with I41/a space group. The band gap (Eg) energy values were estimated and found to range between 4.63–5.32 eV. Scanning electron microscopy (SEM) studies reveled the hexagonal rod-like structures with different Aloe Vera gel concentrations. The particle size was found to be around 40 nm. The vibrational modes of the prepared powders were evaluated by using Fourier Transform Infrared Spectroscopy (FTIR) and Raman spectroscopy. It was observed from the results that, there were 26 vibrational modes of CaMoO4 (Γ=3Ag + 5Au + 5Bg + 3Bu + 5Eg + 5Eu) 8 of which (4Au and 4Eu) were infrared active and 13 (Ag, Bg, and Eg) are Raman active. Photoluminescence (PL) emission intensity increases up to 5 mol% of Eu3+ ions load and subsequently it declines due to the concentration quenching phenomenon and effective energy transfer from Mo-O charge transfer band (CTB) to 5D0 levels of Eu3+. It was noticed from PL emission spectra that, four intense peaks located at 5D0 → 7F1 (590 nm), 5D0 → 7F2 (613 nm), 5D0 → 7F3 (654 nm), 5D0 → 7F4 (702 nm) of Eu3+ respectively. The Commission International de I'Eclairage (CIE) diagram indicates the red color emission and average correlated color temperature (CCT) value was found to be 2050 K. Further, the external quantum efficiency (QE) and color purity (CP) were calculated to check the phosphor efficiency and found to be 92% and 72% respectively. The present investigation opens up a new avenue in the fabrication of low-cost display devices with high color purity and luminous efficacy.

Oxygen corrosion of reboiler tube served in production of dilution steam from heat exchanger of petrochemical refinery

This paper reports the oxygen corrosion of heat exchanger tubes serviced in dilute steam generation system. The floating head heat exchanger employed in a petrochemical industry underwent remnant corrosion failures particularly at lower passes of tube bundle. Initially remote field eddy current inspection technique was employed for tube bundle conditional assessment and further, root cause of degradation of tube had been analyzed. Comprehensive experimental techniques including visual examination, tube chemistry analysis, external tube surface morphological analysis, elemental mapping, scanning electron microscopy, light microscopy and x-ray diffraction studies were employed. The tube surface at the degraded position with its cross sectional examination was rigorously evaluated as well. Moreover, actual steam parameters such as pH, conductivity and iron & chloride concentration have been monitored in the petrochemical facility. The detailed analysis concluded that dissolved oxygen in boiler feed water (BFW) was the root cause for corrosion failure. Several other foreign elements were detected and source of each element was discussed in the context of actual heat exchanger operating conditions. Simulated conditions of BFW service have electrochemically been evaluated in two different dissolved oxygen concentrations at 7.5 ppm and 12.7 ppm, respectively. Even small increase of dissolved oxygen in BFW could lead to promotion of oxygen reduction reaction. Theoretically SA179 tubes operated at pH of 9.75 could lead to formation of bicarbonate and it could protect the tube in absence of dissolved oxygen as evaluated by Molecular Dynamics simulation. However, according to obtained results, tube has been degraded due to presence of dissolved oxygen in BFW. Various contributing factors such as external paint/coat removal, absence of de-aerator system in BFW treatment and improper corrosion inhibitor programme were discussed. Several practical countermeasures have been suggested to mitigate oxygen corrosion failure in petrochemical refineries.

Characterisation of four species of the genus Acrobeloides Cobb, 1924 (Rhabditida, Cephalobidae) from xeric areas in Spain, with revision of the genus and restoration of Paracephalobus Akhtar, 1962

New material of four Acrobeloides species (Acrobeloides arenicola, Acrobeloides bodenheimeri, Acrobeloides nanus and Acrobeloides tricornis) are redescribed from xeric areas in Spain. This species are morphological (based on light microscopy and scanning electron microscopy study) and morphometrically differentiated in two groups. One of them, including A. arenicola, A. nanus and A. tricornis (belonging to the buetschli-group), are characterised by having smaller body, lip region with labial probolae having rectangular base, pharynx with long isthmus, female genital system scarcely developed with vulva midventral, and usually males absent, these with small spicules. Other species group, including A. bodenheimeri (belonging to the maximus-group), is characterised by having longer body, lip region with triangular base, pharynx with very short isthmus, female genital system well developed with vulva usually located ventrolateral, and males frequent with large and robust spicules. This division is corroborate with molecular analyses based on 18S and 28S rDNA. According to this, the separation of the genus Acrobeloides in two different genera is proposed. As Paracephalobus litoralis is morphologically similar to the species of the maximus-group, the genus Paracephalobus is restored to name the species included in the maximus-group. An updated list of species for the genera Acrobeloides and Paracephalobus is included. In addition, Acrobeloides insignis, A. sexlineatus, A. thornei and A. varius are proposed new junior synonyms of A. tricornis.

Lanthanum nanoparticle decorated carbon nanotubes: Facile method of synthesis and studies of their redox stability, cytotoxicity and corrosion inhibition on the magnesium alloy in 3.5 % NaCl environment

Functionalized carbon materials can act as high-temperature coatings and eco-friendly composite materials. We have studied lanthanum-doped carbon nanotube (La-CNT) material redox behavior, cytotoxicity, and corrosion inhibition efficiency. The La-CNT material has been characterized by different techniques to confirm the presence of functional groups. The Fourier transform infrared (FTIR) and Raman studies were performed to investigate the functional groups and carbon defects. Field emission scanning electron microscopy (FESEM) and tunneling electron microscopy (TEM) studies were used to investigate the carbon nanotube microstructure, La nanoparticles were shown to interact with the carbon nanotube surface. X-ray diffraction (XRD) techniques were used to confirm the crystallinity of composite material. Electrochemical methods were used to investigate corrosion inhibition and redox stabilities. After corrosion study on the Mg alloy its microstructure was analyzed to confirm the composite material inhibition efficiency. The composite material showed significant cytotoxicity, and corrosion inhibition efficiency was shown to be 82 % as compared with pristine epoxy-coated Mg alloy.XPS results are suggested that alloy oxide layer formed. The DFT study supported the experimental findings.