Processing and characterization analysis of pyrolyzed oil rubber (from waste tires)‐epoxy polymer blend composite for lightweight structures and coatings applications

In this experimental investigation, the authors have fabricated and characterized composites made from pyrolysis oil rubber and epoxy resin. As the dumping of waste scrap tires poses a serious environmental threat, the pyrolysis oil rubber was extracted from these waste tires only. The prepared blend having pyrolysis oil with various weight percentages (wt%) was examined on the basis of various physical, microstructural, mechanical, and thermal tests. The microstructural tests (scanning electron microscopy and X‐ray diffraction) analysis complemented with the mechanical tests (tensile, compression, flexural, hardness, and impact) results and confirmed that the 4.4 wt% of pyrolysis oil in epoxy resin sample exhibited the best results in toughening of the polymer network. Furthermore, the thermal analysis (differential thermal analysis and thermogravimetric analysis), electrical conductivity, density, water absorption, gas chromatography–mass spectroscopy, and Fourier‐transform infrared tests for the composites were also performed. Low density and high tensile strength than neat epoxy resin makes this composite a potential candidate for fabricating lightweight structures and in polymer coatings for automotive industries. POLYM. ENG. SCI., 59:2041–2051, 2019. © 2019 Society of Plastics Engineers     

Exploring the Molecular Interactions of 7,8-Dihydroxyflavone and Its Derivatives with TrkB and VEGFR2 Proteins

7,8-Dihydroxyflavone (7,8-DHF) is a TrkB receptor agonist, and treatment with this flavonoid derivative brings about an enhanced TrkB phosphorylation and promotes downstream cellular signalling. Flavonoids are also known to exert an inhibitory effect on the vascular endothelial growth factor receptor (VEGFR) family of tyrosine kinase receptors. VEGFR2 is one of the important receptors involved in the regulation of vasculogenesis and angiogenesis and has also been implicated to exhibit various neuroprotective roles. Its upregulation and uncontrolled activity is associated with a range of pathological conditions such as age-related macular degeneration and various proliferative disorders. In this study, we investigated molecular interactions of 7,8-DHF and its derivatives with both the TrkB receptor as well as VEGFR2. Using a combination of molecular docking and computational mapping tools involving molecular dynamics approaches we have elucidated additional residues and binding energies involved in 7,8-DHF interactions with the TrkB Ig2 domain and VEGFR2. Our investigations have revealed for the first time that 7,8-DHF has dual biochemical action and its treatment may have divergent effects on the TrkB via its extracellular Ig2 domain and on the VEGFR2 receptor through the intracellular kinase domain. Contrary to its agonistic effects on the TrkB receptor, 7,8-DHF was found to downregulate VEGFR2 phosphorylation both in 661W photoreceptor cells and in retinal tissue.     

Field Assessment of the Performance of a Ballasted Rail Track with and without Geosynthetics

Understanding the complex mechanisms of stress transfer and strain accumulation in layers of track substructure under repeated wheel loading is essential to predict the desirable track maintenance cycle as well as the design of the new track. Various finite element and analytical techniques have been developed in the past to understand the behavior of composite track layers subjected to repeated wheel loads. The mechanical behavior of ballast is influenced by several factors, including the track confining pressure, type of aggregates, and the number of loading cycles. A field trial was conducted on an instrumented track at Bulli, New South Wales, Australia, with the specific aims of studying the benefits of a geocomposite installed at the ballast-capping interface, and to evaluate the performance of moderately graded recycled ballast in comparison to traditionally very uniform fresh ballast. It was found that recycled ballast can be effectively reused if reinforced with a geocomposite. It was also found that geocomposite can effectively reduce vertical and lateral strains of the ballast with obvious implications for improved track stability and reduced maintenance costs.     

Computational study of 5<Emphasis Type=Italic>d</Emphasis> transition metal mononitrides and monoborides using density functional method

5d-metal mononitrides and monoborides viz. X-N and X-B (X = La, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg) are studied using density functional method based B3LYP functional with LANL2DZ and SDD basis set. The lowest spin state, electron affinities, ionization potentials and binding energies for mononitrides and monoborides are obtained. The electronic state and electronic configuration of mononitrides and monoborides are discussed. Orbitals involved in bond formation are identified. The properties of mononitrides and monoborides are compared. It is found that 5d-metal atoms form stronger bond with nitrogen atom than the boron atom. The range of binding energy, electron affinity and ionization potential is wider for mononitrides than that for monoborides. The properties of 5d-metal mononitrides and 3d-metal mononitrides are also compared. The binding energies for the former are lower than those for the latter.     

Tuning of Cloud Point by the Nature of Surfactant Headgroup: Influence of Counterion and Additives

Work was performed to distinguish the role of sulfonate (–SO₃ ^?) and sulfate (–OSO₃ ^?) with respect to the micellization and clouding phenomenon in ionic surfactant solutions. The clouding phenomenon is a recent addition to the conventional one observed with nonionic surfactants. Three ionic surfactants [sodium dodecylsulfate (SDS), sodium dodecylbenzenesulfonate (SDBS), and sodium dodecylsulfonate (SDSo)] are chosen and the effects of added tetra-n-pentylammonium bromide (TPeAB) and benzyl tributylammonium bromide (BTAC) have been studied on micellization and clouding behaviors in aqueous solution. Based on critical micelle concentration (CMC) and cloud point (CP) measurements, the following order has been observed: SDBS < SDS < SDSo. Though both SDBS and SDSo contain sulfonate groups, they are found at the two ends of the ordering. Therefore, the role of the phenyl ring is also having importance in clouding phenomena. For a typical surfactant, TPeAB was found to be more effective than BTAC. Based on the CP studies, two compositions of SDSo + TPeAB/BTAC were chosen and the effects of different additives (carbohydrate, amino acid, and l-ascorbic acid) on the CP were investigated. Additive may either decrease or increase CP, depending on the structure of the counterion or additive. The present work shows a few novelties: (1) headgroup/counterion dependence of CP and (2) hydrophobicity of counterion/surfactant has an important bearing on the phenomenon. The data can be utilised in improving cloud point extraction methodologies (CPEMs).     

Reduced Maternal Erythrocyte Long Chain Polyunsaturated Fatty Acids Exist in Early Pregnancy in Preeclampsia

The present prospective study examines proportions of maternal erythrocyte fatty acids across gestation and their association with cord erythrocyte fatty acids in normotensive control (NC) and preeclamptic pregnancies. We hypothesize that maternal fatty acid status in early pregnancy influences fetal fatty acid stores in preeclampsia. 137 NC women and 58 women with preeclampsia were included in this study. Maternal blood was collected at 3 time points during pregnancy (16–20th weeks, 26–30th weeks and at delivery). Cord blood was collected at delivery. Fatty acids were analyzed using gas chromatography. The proportions of maternal erythrocyte α‐linolenic acid, docosahexaenoic acid, nervonic acid, and monounsaturated fatty acids (MUFA) (p < 0.05 for all) were lower while total n‐6 fatty acids were higher (p < 0.05) at 16–20th weeks of gestation in preeclampsia as compared with NC. Cord 18:3n‐3, 22:6n‐3, 24:1n‐9, MUFA, and total n‐3 fatty acids (p < 0.05 for all) were also lower in preeclampsia as compared with NC. A positive association was observed between maternal erythrocyte 22:6n‐3 and 24:1n‐9 at 16–20th weeks with the same fatty acids in cord erythrocytes (p < 0.05 for both) in preeclampsia. Our study for the first time indicates alteration in maternal erythrocyte fatty acids at 16th weeks of gestation which is further reflected in cord erythrocytes at delivery in preeclampsia.     

CFD simulation of Taylor–Couette flow in scraped surface heat exchanger

The flow between two concentric cylinders which is termed as Taylor–Couette flow has been studied in scraped surface heat exchanger with and without blades. Shear rate in annular flow with and without blades was measured by Dumont et al. (2000a) using electrochemical method and determined the onset of Taylor vortices at specific Taylor number in both cases for Newtonian flow. CFD simulations have been carried out to determine the transition zone from laminar Couette flow to Taylor vortex flow using the same geometry for which Dumont et al. (2000a) had carried out the experiments. The Reynolds stress model (RSM) and k–? model are used for Taylor vortex flow (Ta > 300) to characterize the flow pattern in annular flow and SSHE respectively. The aim of the present work is to analyze the effect of rotating scraper on the existing flow patterns in simple annular flow using CFD simulations.     

Freestanding chemiresistive polymer composite ribbons as high-flux sensors

Chemiresistive polymer composite ribbons that function as chemical detectors were produced from solution-cast films of polymers and carbon composites. An array with multiple polymer sensor threads was exposed to dimethyl methyl phosphonate, a nerve agent simulant, and different interferents in the vapor phase. Principal component analysis was used to differentiate between the analytes. The response of the ribbon sensors as a function of the carbon composite and the host polymer source was investigated. The freestanding threads/sensors were mounted into a cell perpendicular to the gas flow to provide little pressure drop and were imbedded into fabrics to provide an example of a small, low-cost, wearable chemical sensor. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Multilevel metal interconnection utilizing CVD tungsten and liftoff processing

Interconnections between semiconductor devices in integrated circuits continue to present difficult problems in the tradeoffs between RC time constants, production worthiness, reliability, structural complexity, and compactibility for any single technology. A process and structure has been demonstrated for integrated circuit interconnections which uses a conformai tungsten layer deposited by chemical vapor deposition to provide step coverage into via holes of variable height. The film is then patterned with a via interconnect pattern designed for liftoff processing, layers of chromium copper and chromium are then depositedinsitu on the wafers by way of evaporation. The undesired material is lifted off in a solvent process and the resulting metal pattern is used as the mask for the reactive ion etching of CVD tungsten. This combination of materials and process allows for high conductivity reliable interconnections with negligable step coverage problems. Processing and test information will be presented in the paper.     

Stress Spikes in Pin and Hanger System of Truss Bridge

Several functional problems have been reported on pin and hanger system truss bridges, such as frozen pins, stress spikes in hangers, lack of expansion joint movements, etc. It has been difficult to develop a pin and hanger retrofit strategy because the cause for the observed problems is usually unknown. This paper presents a study performed on the pin and hanger system of one such bridge—the Newburgh Beacon bridge. Extensive field testing performed so far has failed to identify the cause for the observed stress spikes. The concept of misalignment loading is developed in this article to explain the observed behavior. Stress spikes predicted using this concept matched very well with the observed stress spikes. Finally, the use of misalignment loading to evaluate other truss members is also discussed.