Experimental and computational approach on the development of a new Green corrosion inhibitor formulation for N80 steel in 20% formic acid.

Organic acids are employed as scale dissolvers in the oil & gas industry during production to stimulate oil recovery by pumping in the formations. Corrosion of metallic surfaces in organic acid solutions poses a significant issue in the oil and gas sector. In recent years, considering the stringent environmental regulations, there has been a growing research interest in environmentally safe inhibitors. This paper explores the synthesis of 2-(3-(carboxymethyl)-1H-imidazol-3-ium-1-yl) acetate (IZ) and its first-time application for corrosion mitigation of N80 steel in 20% formic acid. A detailed experimental study involving gravimetric, electrochemical, and surface analytical techniques is reported herein. The electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) analyses suggest a rise of impedance with IZ and a mixed-type inhibition behavior, respectively. The inhibition efficiency (IE) is 99.54% at 200 mg/L at 308 K, reaching 99.4% at 363 K with the introduction of KI as a synergistic agent. Computational studies revealed that the inhibitor IZ gets protonated in the experimental environment. The protonated form shows a tendency to receive electrons from the metal surface and shows a greater energy of adsorption compared to that of the neutral form.

The development of a novel Wellness Assessment Instrument and its use in the assessment of wellness status in patients with chronic obstructive pulmonary disease.

AIMS: Chronic obstructive pulmonary disease (COPD) is a chronic respiratory disorder that affects health outcomes on multiple levels including overall wellbeing. More specifically, factors such as spiritual wellbeing, and psychological, mental and motivational status which may be at least as important as others, have been rarely studied. This article reports the method of validating a new wellness assessment questionnaire and the status of several wellness domains in patients with COPD. METHODS: The study consisted of two phases: first, the development of a new Wellness Questionnaire with the help of focus groups; second, the validation and use of the questionnaire in a cohort of patients with COPD. For focus groups, healthy people ⩾45 years of age with no known comorbidity as well as people with a clinical diagnosis of COPD were invited to participate in the study. RESULTS: Thematic analysis of findings from focus groups and original cohort respondents highlighted some factors that appear to influence wellness status. Five domains were explored as potential markers of wellness in patients with COPD. Quantitative analysis with Spearman correlation demonstrated a significant correlation between Physical/Personal Wellness and other markers of COPD progression such as Global Initiative Obstructive Lung Disease (GOLD; 0.006), force expiratory volume in 1 s (FEV1%; 0.01), health-related quality of life (0.009), multidimensional BOD score and quartile (0.003 and 0.02). CONCLUSION: The findings suggest that a combination of personal, physical, emotional, mental and other psychological factors is responsible for negative COPD outcomes. While there is a need to validate this new wellness questionnaire in further research, it incorporates new markers of wellness that could benefit management of COPD.

Evolving concepts in ventral hernia repair and physical therapy: prehabilitation, rehabilitation, and analogies to tendon reconstruction.

PURPOSE: The abdominal wall and musculoskeletal tendons share many anatomic, physiologic, and functional characteristics. This review aims to highlight these similar characteristics and to present a rationale why the treatment principles of successful musculoskeletal tendon reconstruction, including principles of surgical technique and physical therapy, can be used in the treatment of complex abdominal wall reconstruction or ventral hernia repair. METHODS: The MEDLINE/PubMed database was used to identify published literature relevant to the purpose of this review. CONCLUSIONS: There are several anatomical and functional similarities between the linea alba and musculoskeletal tendons. Because of this reason, many of the surgical principles for musculoskeletal tendon repair and ventral hernia repair overlap. Distribution of tension is the main driving principle for both procedures. Suture material and configuration are chosen to maximize tension distribution among the tissue edges, as seen in the standard of care multistrand repairs for musculoskeletal tendons, as well as in the small bites for laparotomy technique described in the STITCH trial. Physical therapy is also one of the mainstays of tendon repair, but surprisingly, is not routine in ventral hernia repair. The evidence surrounding physical therapy prehabilitation and rehabilitation protocols in other disciplines is significant. This review challenges the fact that these protocols are not routinely implemented for ventral hernia repair, and presents the rationale and feasibility for the routine practice of physical therapy in ventral hernia repair.

Question 5: Magnesium Sulphate for Acute Asthma in children.

Most children who present to the emergency department with acute asthma, respond well to inhaled ß2-agonists (spacer or nebuliser), oxygen (if required) and systemic steroids. Guidelines across the world agree on this simple, straight forward evidenced based approach. In children with more severe asthma attacks and those who do not respond to initial treatment, the evidence base for the secondary level treatment is less clear. Many regimens exist for the next step. Intravenous Magnesium Sulphate (MgSO4) is now used frequently in these situations and some centres are starting to use nebulized MgSO4 as part of the initial maximal inhaled therapy options. This paper examines the role of MgSO4 in acute asthma in children. It focusses on how MgSO4 might work, what are the current recommendations for use and then what is the current evidence base to support its use. We have presented the evidence for the use of both nebulized and intravenous MgSO4. At the end of the paper we have suggested future directions for research in this area. Our aim is to present a synthesis of the current role of MgSO4 in the management of an acute asthma attack.

Chitosan-cinnamaldehyde Schiff base: A bioinspired macromolecule as corrosion inhibitor for oil and gas industry.

A Schiff base of chitosan with cinnamaldehyde (Cinn-Cht) was synthesized in a single step using microwave irradiation and characterized using spectroscopic techniques. The synthesized Schiff base was used for the mitigation of carbon steel corrosion in 15% HCl. The corrosion evaluation was performed using weight loss tests, electrochemical impedance measurements, and polarization studies. The corrosion inhibition efficiency increased with inhibitor dosage and achieved a high value of 85.16% at 400 mgL-1. The inhibitor adsorption followed the Langmuir isotherm and displayed a mixed physical and chemical adsorption behavior. To further improve the corrosion inhibition efficiency, potassium iodide (KI) was incorporated in the corrosive solution, which increased the inhibition efficiency further to 92.45% at a concentration of 10 mM. Surface studies carried out via SEM analyses indicated the inhibitor adsorption and protective film formation on the steel surface. The computational studies carried out via DFT revealed that mainly the protonated form of inhibitor adsorbs on the metal surface. Monte Carlo simulation studies also showed that the protonated form of the inhibitor molecule exhibited higher adsorption energy than the neutral inhibitor.

Microwave-assisted synthesis of a new Piperonal-Chitosan Schiff base as a bio-inspired corrosion inhibitor for oil-well acidizing.

A new Schiff base of chitosan, namely Piperonal-chitosan (Pip-Cht), was synthesized for the first time, using a microwave irradiation method and characterized using spectroscopic techniques. The corrosion inhibition behavior of the new Schiff base was evaluated on carbon steel in 15% HCl medium via gravimetric and electrochemical techniques. This is the first work on the application of chemically functionalized chitosan as a corrosion inhibitor in the oil-well acidizing environment. The Pip-Cht inhibitor exhibited a high corrosion inhibition efficiency of 85.16% at a moderate dose of 600 mg L-1. Further, the addition of potassium iodide as a synergistic agent to the corrosive electrolyte produced a significant improvement in the inhibition efficiency to 91.15% at a low dosage of 10 mM of KI. At a higher temperature of 65 °C, the combination of both the inhibitor and KI yielded a high inhibition efficiency. The results of the gravimetric and electrochemical experiments were corroborated using AFM and SEM studies. The DFT calculations indicated that corrosion inhibition behavior of the Schiff base mainly occurs in the protonated form.

Bis(2-aminoethyl)amine-modified graphene oxide nanoemulsion for carbon steel protection in 15% HCl: Effect of temperature and synergism with iodide ions.

HYPOTHESIS: There is a scarcity of available literature studies on the inhibition of aqueous corrosion using graphene and graphene oxide (GO) due to their poor aqueous solubility. The abundance of oxygen-containing functional groups on the surface of GO offers promising aspects for its chemical modification. Accordingly, we herein report the application of bis(2-aminoethyl)amine-modified graphene oxide (B2AA-GO) as a corrosion inhibitor for carbon steel in industrial oil-well acidizing conditions. EXPERIMENTS: B2AA was used to modify the graphene oxide (GO) chemically and characterized using FTIR, SEM, and TEM. The corrosion evaluations were undertaken in 15% HCl using weight loss, electrochemical impedance spectroscopy, and potentiodynamic polarization techniques supported by a thorough surface analysis using water contact angle measurements, FTIR, and atomic force microscopy. FINDINGS: It observed that the B2AA-GO acted by adsorption on the metal surface and exhibited a mixed type of nature with cathodic prevalence. The results showed that the chemically modified GO exhibits excellent inhibition behavior showing 90.27% corrosion inhibition efficiency up to 65 °C. Furthermore, iodide ions were introduced to improve the inhibition efficiency of the GO via synergistic action and inhibition efficiency of 96.77% was obtained at 65 °C. The obtained results show that the chemically modified GO is a promising corrosion inhibitor in the acidizing environment.

The synergistic influence of polyethyleneimine-grafted graphene oxide and iodide for the protection of steel in acidizing conditions.

Herein, graphene oxide (GO) was chemically functionalized with polyethyleneimine (PEI) in a single step to obtain PEI-GO, which was characterized via FTIR spectroscopy, SEM, and TEM. Additionally, for the first time, PEI-GO was employed for the corrosion mitigation of carbon steel in a solution of 15% HCl. The corrosion performance of the inhibitor was evaluated by utilizing weight loss tests, electrochemical measurements with impedance analysis, electrochemical frequency modulation, and potentiodynamic polarization studies. Thorough surface analysis was performed using 3D profilometry and static water contact angle measurements. PEI-GO was adsorbed on the steel surface and showed mixed-type corrosion inhibition behavior with the prevalence of cathodic characteristics. Additionally, potassium iodide was incorporated in the acid solution as a synergistic agent to enhance the corrosion inhibition behavior of PEI-GO. The obtained results showed that PEI-GO alone provided a high corrosion inhibition efficiency of 88.24% at a temperature of 65 °C and in the presence of KI, it showed an I.E. of 95.77% due to their synergistic effect. These interesting results demonstrate that PEI-GO can act as a potential corrosion inhibitor in acidizing conditions. The DFT-based computational studies showed that the inhibitor functioned in both its neutral and protonated forms.

Chitosan Schiff base: an environmentally benign biological macromolecule as a new corrosion inhibitor for oil & gas industries.

An eco-friendly Schiff base, namely Salicylaldeyde-Chitosan Schiff Base (SCSB), was synthesized by the reaction of chitosan and salicylaldehyde. In 3.5% NaCl saturated with carbon dioxide at 65 °C corrosion inhibition effect was analyzed using weight loss, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) methods. The PDP results revealed that SCSB acts as a mixed type inhibitor and reduces the corrosion process effectively at 150 mg L-1 concentration with an inhibition efficiency of 95.2% and corrosion rate of 0.444 mm/y. EIS measurements suggest that the corrosion inhibition process is kinetically controlled. Langmuir adsorption model is the best fit among the other tested isotherms. The surface analysis was carried out using scanning electron microscopy (SEM), atomic force microscopy (AFM), scanning Kelvin probe (SKP), and X-ray photoelectron spectroscopy (XPS) to corroborate the formation of inhibitor film on the metal surface. Computational studies showed the effective adsorption of the protonated form of inhibitor.

Comprehensive investigation of steel corrosion inhibition at macro/micro level by ecofriendly green corrosion inhibitor in 15% HCl medium.

HYPOTHESIS: In the present time, there is enormous need for environmentally friendly and effective corrosion inhibitor for the acidizing process. During acidization 15% hydrochloric acid is used, which causes corrosion of N80 steel. EXPERIMENTS: The present study aims at the synthesis of environmentally benign corrosion inhibitor, namely 2-amino-4-(5-hydroxy-3-methyl-1H-pyrazole-4-yl)-4H-chromene-3-carbonitrile (PCP), and corrosion inhibition evaluation for N80 steel in 15% HCl. The inhibition potential of PCP was examined by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), density functional theory (DFT), and molecular dynamics simulation (MSD). The surface morphology of N80 steel samples was characterized by atomic force microscopy (AFM), contact angle measurement, UV-vis spectroscopy, and scanning electron microscopy (SEM). FINDINGS: The EIS measurements disclosed that PCP inhibits corrosion via kinetic controlled process. PDP results confirmed that PCP is a mixed type inhibitor and reduces the corrosion process effectively at 400 mg/L concentration with 98.4% efficiency. The adsorption of PCP followed Langmuir isotherm. Surface analysis by SEM, AFM, contact angle measurement, and UV-vis spectroscopy supports PCP adsorption over the N80 steel surface. The DFT study explores the adsorption and reactive regions of the PCP molecules. The MSD reveals that the diffusion co-efficient of the corrosive species in inhibited solution is less as compared to uninhibited.

Corrigendum to "Dietary administration of Nexrutine inhibits rat liver tumorigenesis and induces apoptotic cell death in human hepatocellular carcinoma cells". [Toxicol. Rep. 2 (2014) (November) 1-11].

[This corrects the article DOI: 10.1016/j.toxrep.2014.11.006.].

Thiosemicarbazide and thiocarbohydrazide functionalized chitosan as ecofriendly corrosion inhibitors for carbon steel in hydrochloric acid solution.

Organically functionalized chitosan macromolecules namely Chitosan-Thiosemicarbazide (CS-TS) and Chitosan-Thiocarbohydrazide (CS-TCH) were synthesized and evaluated as new corrosion inhibitors for mild steel corrosion in 1M HCl. The FTIR and 1H NMR studies confirmed the formation of the derivatives. The corrosion tests were performed using weight loss method, electrochemical measurements, surface morphology (AFM), quantum chemical investigation and molecular dynamics simulation methods. The maximum efficiency of 92% was obtained at a concentration as low as 200mgL-1. The inhibitors were found to obey Langmuir adsorption isotherm and exhibited both physical and chemical adsorption. Electrochemical impedance spectroscopy (EIS) results showed an increase in polarization resistance which supported the adsorption of inhibitors on the mild steel surface. Tafel data showed a mixed type behavior with cathodic predominance. The data of quantum chemical calculations and molecular dynamics simulation supported the experimental findings.

An impending inhibitor useful for the oil and gas production industry: Weight loss, electrochemical, surface and quantum chemical calculation.

The influence of a Schiff base namely N,N'-(pyridine-2,6-diyl)bis(1-(4-methoxyphenyl) methanimine) (PM) on the corrosion of J55 and N80 steel in 3.5 wt.% NaCl solution saturated with CO2 was evaluated using weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), X-ray diffraction (XRD), contact angle, scanning electron microscopy (SEM), atomic force microscopy (AFM) and scanning electrochemical microscopy (SECM). Potentiodynamic polarization results suggested that the inhibitor acted as a mixed type inhibitor by reducing both anodic and cathodic reactions. The adsorption of PM on the J55 and N80 steel surface obeyed the Langmuir adsorption isotherm. XRD, contact angle, SEM, AFM and SECM studies revealed that the surface of the metal was quite unaffected after the addition of inhibitor. Quantum chemical calculations and molecular dynamic simulation support the experimental results well.

Theoretical, thermodynamic and electrochemical analysis of biotin drug as an impending corrosion inhibitor for mild steel in 15% hydrochloric acid.

The corrosion mitigation efficiency of biotin drug for mild steel in 15% hydrochloric acid was thoroughly investigated by weight loss and electrochemical methods. The surface morphology was studied by the contact angle, scanning electrochemical microscopy, atomic force microscopy and scanning electron microscopy methods. Quantum chemical calculation and Fukui analysis were done to correlate the experimental and theoretical data. The influence of the concentration of inhibitor, immersion time, temperature, activation energy, enthalpy and entropy has been reported. The mitigation efficiency of biotin obtained by all methods was in good correlation with each other. Polarization studies revealed that biotin acted as a mixed inhibitor. The adsorption of biotin was found to obey the Langmuir adsorption isotherm. Surface studies showed the hydrophobic nature of the steel with inhibitor and vindicated the formation of a film on the metal surface that reduced the corrosion rate.

How to repair the surgical defect after excision of sacrococcygeal pilonidal sinus: a dilemma.

OBJECTIVE: Although there are various therapeutic modalities to manage patients suffering from sacrococcygeal pilonidal sinus disease, there remains controversy over a standard method to treat such patients. In this study the postoperative outcomes after three different surgical methods of wound repair in patients with sacrococcygeal pilonidal sinus were compared. METHOD: Patients were divided randomly into three different groups. All of the patients underwent a wide excision of their pilonidal sinus; the subsequent surgical wound was left open in the first group (lay open group) whereas it was repaired with a simple primary closure and a rhomboid flap in the second and third groups. Variables including length of hospitalisation, time for wound healing, time off work, recurrence and surgical complications were evaluated. RESULTS: A total of 60 patients with an average age of 27.61 years were studied, including 47 (78.3%) men and 13 (21.7%) women. Postoperative hospitalisation time was significantly shorter in patients who were treated using the simple primary closure method than those with the rhomboid flaps. However, there were no differences in terms of postoperative hospitalisation time between the lay open and simple primary groups or the lay open and rhomboid groups. The period of absence from work was significantly shorter in patients who were managed by a simple primary closure or rhomboid flap technique comparing to those whose wound was left open (p<0.05). Complete wound healing had a significantly shorter course in the rhomboid flap and the simple primary closure techniques compared to those within the lay open group. In terms of complications, postoperative infection and haemorrhage were more common in the lay open group than in the other two. Recurrence was about 5% in patients who were treated with the lay open method in an 18-month follow-up period; however, no recurrence was observed in the other two groups. CONCLUSION: Considering the earlier wound healing period, less days absent from work, lower complication levels and recurrence rates, the simple primary closure or rhomboid flap techniques appear to be better options to treat the subsequent wound after a wide excision of pilonidal sinus when compared to the lay open method. The simple primary closure method causes no cosmetic disfiguration and the most promising option among the three techniques assessed. DECLARATION OF INTEREST: The authors have declared that no conflict of interest exists.

Fabrication of silicon molds with multi-level, non-planar, micro- and nano-scale features.

A method for single-step fabrication of arbitrary, complex, three-dimensional (3D) silicon structures from the nano- to millimeter-scale at multiple levels on non-planar, curved, or domed surfaces is reported. The fabrication is based on focused or masked ion beam irradiation of p-type silicon followed by electrochemical anodization. The process allows fabrication of a wide range of surface features at multiple heights and with arbitrary orientations by varying the irradiated feature width, ion type, energy fluence, and subsequent anodization conditions. The technology has achieved depth resolution of 10 nm as step heights and is capable of creating lateral features down to 7 nm at high aspect ratios of up to 40, with surface roughness down to 1 nm scaled up to full wafer areas. The single-step ability has seamlessly interfaced a network of complex, integrated micro- to nano-structures in 3D orientations with no alignment required. The final template has been converted to a master copy for nano-imprinting lithography of 3D fluidic structures and optical components.

Interaction of free-living marine nematodes in the artificial mangrove environment (Southeast Coast of India).

Free-living marine nematode diversity was analyzed between Avicennia marina and Rhizophora mucronata mangrove covers of the Vellar Estuary (southeast coast of India). A total of 4,976 specimens of free-living marine nematodes were collected in 56 species. Comparatively, a higher species richness was obtained for A. marina (52 species) than for R. mucronata (44 species), whereas 40 species commonly existed in both mangrove covers. A higher density of nematodes was found in sediments of sandy nature, whereas there was lower total organic carbon compared to silt/clay composition; epigrowth feeders were dominant over the other feeding groups based on organic enrichment in surface sediments. Principal component analysis clearly explained the relationship between the environmental parameters of various months. Higher R values of analysis of similarities revealed significant differences in nematode assemblages between months, and it was quite evident by non-metric multidimensional scaling. Diversity indices showed higher values in the dry months. RELATE analysis explained serial changes in nematode species composition between months, and a relationship between biotic and abiotic variables was clarified using the BIO-ENV procedure. Viscosia spp., Metachromadora spp., Theristus spp., and Sphaerolaimus spp. were candidate species of A. marina leaf interaction by observation.

Methodological quality and descriptive characteristics of prosthodontic-related systematic reviews.

Ideally, healthcare systematic reviews (SRs) should be beneficial to practicing professionals in making evidence-based clinical decisions. However, the conclusions drawn from SRs are directly related to the quality of the SR and of the included studies. The aim was to investigate the methodological quality and key descriptive characteristics of SRs published in prosthodontics. Methodological quality was analysed using the Assessment of Multiple Reviews (AMSTAR) tool. Several electronic resources (MEDLINE, EMBASE, Web of Science and American Dental Association's Evidence-based Dentistry website) were searched. In total 106 SRs were located. Key descriptive characteristics and methodological quality features were gathered and assessed, and descriptive and inferential statistical testing performed. Most SRs in this sample originated from the European continent followed by North America. Two to five authors conducted most SRs; the majority was affiliated with academic institutions and had prior experience publishing SRs. The majority of SRs were published in specialty dentistry journals, with implant or implant-related topics, the primary topics of interest for most. According to AMSTAR, most quality aspects were adequately fulfilled by less than half of the reviews. Publication bias and grey literature searches were the most poorly adhered components. Overall, the methodological quality of the prosthodontic-related systematic was deemed limited. Future recommendations would include authors to have prior training in conducting SRs and for journals to include a universal checklist that should be adhered to address all key characteristics of an unbiased SR process.