•Tagetes erecta extract is a green corrosion inhibitor for mild steel in 0.5M H2SO4.•Inhibition efficiency increases with concentration but decreases with temperature.•It acts as a mixed ...inhibitor.•It inhibits the corrosion through the physical adsorption of Lutein.
The extract of Tagetes erecta (Marigold flower) TEE has been evaluated as a corrosion inhibitor for mild steel in 0.5M H2SO4 solution by means of gravimetric, potentiodynamic polarization and electrochemical impedance spectroscopic measurements. Tafel polarization studies reveal that TEE acts as an efficient mixed inhibitor. The adsorption of the inhibitor on the mild steel (MS) surface follows the Langmuir adsorption isotherm, indicating monolayer adsorption. The activation parameters governing adsorption show that the inhibitor is physically adsorbed. The results of quantum chemical calculation indicate high feasibility of adsorption of molecular and protonated Lutein, a major component of TEE.
Mitochondrial dysfunction plays a very vital role in the pathogenesis of Alzheimer’s disease (AD). Several shreds of evidence have indicated that the mitochondrial function is severely compromised ...under AD pathogenesis. Most of the recent therapeutic strategies have been conversed to treat AD by pinpointing the pathways involved in the pathophysiology of AD. In AD, mitochondria progressively lose their proper functions that are ultimately responsible for their accumulation and removal via the autophagic process, which is called mitophagy that further worsens the progression of this incapacitating disease. Preclinical and clinical studies have suggested that mitochondrial dysfunction along with mitophagy significantly contributes to the accumulation of amyloid-beta (Aβ) fibrils and hyperphosphorylated tau protein tangles which lead to synaptic dysfunctions and cognitive impairments such as memory loss through reactive oxygen species (ROS)–mediated pathway. The present review is intended to discuss the recent advancements in the frontiers of mitochondrial dysfunction and consequent therapeutic strategies that have been employed to treat AD.
Physical and cognitive exercise may prevent or delay dementia in later life but the neural mechanisms underlying these therapeutic benefits are largely unknown. We examined structural and functional ...magnetic resonance imaging (MRI) brain changes after 6 months of progressive resistance training (PRT), computerized cognitive training (CCT) or combined intervention. A total of 100 older individuals (68 females, average age=70.1, s.d.±6.7, 55-87 years) with dementia prodrome mild cognitive impairment were recruited in the SMART (Study of Mental Activity and Resistance Training) Trial. Participants were randomly assigned into four intervention groups: PRT+CCT, PRT+SHAM CCT, CCT+SHAM PRT and double SHAM. Multimodal MRI was conducted at baseline and at 6 months of follow-up (immediately after training) to measure structural and spontaneous functional changes in the brain, with a focus on the hippocampus and posterior cingulate regions. Participants' cognitive changes were also assessed before and after training. We found that PRT but not CCT significantly improved global cognition (F(90)=4.1, P<0.05) as well as expanded gray matter in the posterior cingulate (P
<0.05), and these changes were related to each other (r=0.25, P=0.03). PRT also reversed progression of white matter hyperintensities, a biomarker of cerebrovascular disease, in several brain areas. In contrast, CCT but not PRT attenuated decline in overall memory performance (F(90)=5.7, P<0.02), mediated by enhanced functional connectivity between the hippocampus and superior frontal cortex. Our findings indicate that physical and cognitive training depend on discrete neuronal mechanisms for their therapeutic efficacy, information that may help develop targeted lifestyle-based preventative strategies.
► Polyacrylamide grafted with Okra mucilage is a biodegradable co-polymer. ► It is an effective green corrosion inhibitor for mild steel in 0.5M H2SO4. ► The inhibition efficiency is both ...concentration and time dependent. ► It acts as a predominantly cathodic inhibitor. ► Physically adsorbed polymer film on the metal surface restricts the corrosion.
A new green polymeric material, polyacrylamide grafted with Okra mucilage, a natural grade polysaccharide, was tested as corrosion inhibitor for mild steel in 0.5M H2SO4 using gravimetric and electrochemical techniques. The inhibition efficiency was found to increase with increasing inhibitor concentration up to maximum 96.6% for 100ppm at 25°C. The effects of immersion time (3–72h) and temperature (25–65°C) on the inhibition of corrosion have also been discussed. The adsorption of this inhibitor on the mild steel surface obeys a Langmuir adsorption isotherm. The scanning electron micrographs of the inhibited specimens show smoothening of the surface.
The Himalayan ecosystem is one of the sensitive and fragile ecosystems with rich biodiversity that provides major ecosystem services. The study was conducted to measure the extent of vulnerability ...across forested grids of Uttarakhand—one of the States of Indian Western Himalayan (IWH) region. The forests of the state are exposed to various anthropogenic and natural climatic pressures, thus making them vulnerable. In this paper, we demonstrate how to map vulnerability of forest ecosystem by analyzing variability and trends of net primary productivity (NPP). The vulnerability of the forest ecosystem was evaluated through trends of sensitivity and adaptability of NPP. The sensitivity of a system was considered as the response degree of the system to climatic variability whereas adaptability was considered as the ability to maintain, recover or improve its structure in the face of climatic stresses. In our study, NPP was considered as the receptor of shock and stresses of climatic variability and human disturbances. We discuss the method and results with reference to productivity changes under the influence of changing climate for the forested landscape of a mountainous region. The results have been summarized to rank vulnerability at the level of administrative boundary of governance, i.e. district. Average value of vulnerability for all NPP pixels of forests grids in a district was used to compute the vulnerability at district level. The study will help forest managers in decision making for efficiently allocating resources and to prioritize management options in the identified regions to improve productivity in coming times.
Blast induced rock mass damage around tunnels Verma, H.K.; Samadhiya, N.K.; Singh, M. ...
Tunnelling and underground space technology,
January 2018, 2018-01-00, 20180101, Letnik:
71
Journal Article
Recenzirano
Drilling and blasting is a preferred method of rock excavation world-wide due to low initial investment, cheap explosive energy, easy acceptability among the blasting engineers and, possibility to ...deal with different shapes and sizes of openings. Although, drill and blast method has witnessed significant technological advancements, it has inherent disadvantage of deteriorating surrounding rock mass due to development of network of fine cracks in it leading to safety and stability problems. The damage in the peripheral rock mass culminates in the form of overbreak and damaged zone beyond overbreak. In some cases the projects cost has increased more than 15% because of overbreak. Although significant efforts have been made to assess damage to the surrounding rock mass using different methods, the solution based on easily available site parameters is still lacking. Authors have carried out field investigations at five different tunnels located in Himalaya, India to study blast induced damage for wide range of rock mass quality Q values (0.03–17.8). In addition to Q, specific charge, perimeter charge factor, maximum charge per delay, advancement and confinement factors have also been used. Data sets of 113 experimental blasts are collected from the five tunnel sites. All the parameters, easily available to the site engineers, have been used for developing an empirical correlation to estimate the rock mass damage around the tunnel, which is discussed in the paper. The proposed empirical correlation has been validated using ultrasonic tests on rock core samples obtained from one of the experimental location.
Background
During the last two decades, an increasing number of bariatric surgical procedures have been performed worldwide. There is no consensus regarding optimal perioperative care in bariatric ...surgery. This review aims to present such a consensus and to provide graded recommendations for elements in an evidence-based “enhanced” perioperative protocol.
Methods
The English-language literature between January 1966 and January 2015 was searched, with particular attention paid to meta-analyses, randomised controlled trials and large prospective cohort studies. Selected studies were examined, reviewed and graded. After critical appraisal of these studies, the group of authors reached a consensus recommendation.
Results
Although for some elements, recommendations are extrapolated from non-bariatric settings (mainly colorectal), most recommendations are based on good-quality trials or meta-analyses of good-quality trials.
Conclusions
A comprehensive evidence-based consensus was reached and is presented in this review by the enhanced recovery after surgery (ERAS) Society. The guidelines were endorsed by the International Association for Surgical Metabolism and Nutrition (IASMEN) and based on the evidence available in the literature for each of the elements of the multimodal perioperative care pathway for patients undergoing bariatric surgery.
Limited data exist on procedural and biophysical indicators of pulmonary vein (PV) isolation durability after the cryoballoon ablation of atrial fibrillation (AF).
The aim of this study was to ...investigate the procedural and biophysical characteristics associated with late PV reconnection (PVR) and durable PV isolation (PVI) after cryoablation using the currently available second-generation cryoballoon.
Data from 435 PVs targeted in 112 consecutive patients who underwent a repeat procedure 14 ± 3 months after an index cryoablation of AF were examined.
Altogether, 111 PVs (25.5%) in 71 patients (63.4%) demonstrated PVR, whereas 324 PVs (74.5%) exhibited PVI. The number and duration of cryoballoon applications did not differ between PVR and PVI. However, the time to PV isolation (time to effect) was considerably shorter (39.1 ± 11.7 seconds vs 67.6 ± 19.7 seconds; P < .001), the balloon temperature at time to effect was significantly warmer (−32.1°C ± 7.8°C vs −39.4°C ± 5.8°C; P < .001), the balloon nadir temperature was slightly cooler (−48.7°C ± 4.6°C vs −47.8°C ± 2.9°C; P = .034), and the total thaw time (56.5 ± 25.4 seconds vs 34.8 ± 9.1 seconds; P < .001) and interval thaw times at 0°C (iTT0; 14.8 ± 10.9 seconds vs 7.1 ± 2.0 seconds; P < .001) and 15°C (54.2 ± 25.4 seconds vs 33.3 ± 9.1 seconds; P < .001) were notably longer with PVI than with PVR. However, only a time to effect of ≤60 seconds and an iTT0 of ≥10 seconds emerged as significant predictors of PV isolation durability. Consequently, in a multivariate model, presence of both criteria predicted <1% and their mere absence ~75% likelihood of PVR.
A time to effect of ≤60 seconds and an iTT0 of ≥10 seconds significantly predict PV isolation durability after the cryoballoon ablation of AF. If both criteria are met, the likelihood of PV reconnection may be exceedingly low.
A phenomenological model based on thermodynamical variables is used to analyze the optical properties of nanomaterials. The expression of cohesive energy given by Qi and Wang model is extended to ...study the variation of the energy band gap, vibrational frequency, and static dielectric constant with size for nanoparticles, nanowires, and nanofilms. The energy bandgap is observed to increase in nanostructures with a reduction in size while the reduction in the vibrational frequency of nanostructures is found with a decrease in size from model calculations. The dielectric constant is also found decreasing with the size reduction of the nanostructure to the nanoscale. As the number of surface atoms changes with change in the shape of the nanomaterial, the shape effect on optical properties is also studied. The size and shape effect are found prominent in nanostructures up to the size limit of approximately 30 nm; however, the effect of size and shape becomes less significant as the size is more than 30 nm. The model predictions are consistent with the available experimental and simulated trend which supports the validity of the model theory.
Molecular scale understanding of the mechanism of solution-mediated nucleation and the growth of crystalline materials in the presence of growth inhibitors together with the process parameters ...continues to attract the interest of the scientific community though much headway has been made in recent years. Growth inhibitors can be added to solution of a crystallizing parent molecule to alter the rate of growth of different crystal faces, size and shape of the crystalline materials. In this work, we investigated the effects of a number of shape-controlling inhibitors, such as acetone, biuret and biurea, on the growth kinetics of the various faces of aqueous-grown urea crystals as a means to predictably control the crystal growth morphology. We combined the adsorption energy landscape of various auxiliaries with the kinetics of the molecular growth processes to develop an analytical model to compute the rate of growth as a function of supersaturation and the additive concentration. The model relates the kinetic and thermodynamic aspects of the adsorption of the solute, solvent and additive to provide a quantitative description of the crystal growth.
Ab initio
periodic dispersion-corrected density functional theory using the hybrid exchange-correlation functional was employed to determine the interfacial structure of the adsorption of various auxiliaries at crystalline surfaces. The calculated adsorption energies of different auxiliaries were employed to examine the role played by these auxiliaries during the aqueous crystallization of urea crystals containing small amounts of additives. Our results showed that the growth of (110), (111) and (1&cmb.macr;1&cmb.macr;1&cmb.macr;) faces were nearly unaltered by the addition of moderate amounts of acetone as it has lower adsorption energies with the surfaces of these faces. Nevertheless, the presence of acetone in the solution reasonably impeded the growth of the (001) face. The addition of biuret or biurea in the solution led to a higher adsorption energy at (001) and (111) faces. Consequently, the low concentration of these additives severely obstructed the growth of (001) and (111) faces as most of the adsorption sites were occupied by these additives. On the other hand, these additives were weakly adsorbed at the (110) face and, hence, the growth of the (110) face largely remained unaltered. Moreover, unlike biuret, biurea considerably inhibited the growth of the (1&cmb.macr;1&cmb.macr;1&cmb.macr;) face. Our results are in agreement with the experimental and computational results reported in the literature.
Effect of different growth additives on the aqueous growth of crystalline urea is investigated computationally at the different levels of supersaturation and additive concentration.
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