Rheo-PIV of a shear-banding wormlike micellar solution under large amplitude oscillatory shear

We explore the behavior of a wormlike micellar solution under both steady and large amplitude oscillatory shear (LAOS) in a cone–plate geometry through simultaneous bulk rheometry and localized velocimetric measurements. First, particle image velocimetry is used to show that the shear-banded profiles observed in steady shear are in qualitative agreement with previous results for flow in the cone–plate geometry. Then under LAOS, we observe the onset of shear-banded flow in the fluid as it is progressively deformed into the non-linear regime—this onset closely coincides with the appearance of higher harmonics in the periodic stress signal measured by the rheometer. These harmonics are quantified using the higher-order elastic and viscous Chebyshev coefficients e [subscript n] and v [subscript n] , which are shown to grow as the banding behavior becomes more pronounced. The high resolution of the velocimetric imaging system enables spatiotemporal variations in the structure of the banded flow to be observed in great detail. Specifically, we observe that at large strain amplitudes (γ [subscript 0] ≥ 1), the fluid exhibits a three-banded velocity profile with a high shear rate band located in-between two lower shear rate bands adjacent to each wall. This band persists over the full cycle of the oscillation, resulting in no phase lag being observed between the appearance of the band and the driving strain amplitude. In addition to the kinematic measurements of shear banding, the methods used to prevent wall slip and edge irregularities are discussed in detail, and these methods are shown to have a measurable effect on the stability boundaries of the shear-banded flow.Spain. Ministerio de Educación y Ciencia (MEC) (Project FIS2010-21924-C02-02

Structure sensitivity of selective CO oxidation over Pt/gamma-Al2O3

In this study, the effect of particle size on the reaction rate and selectivity of preferential oxidation of CO (PROX) reaction was investigated on 2 wt% Pt/-Al2O3 catalysts prepared by an incipient wetness technique. The particle size of the catalysts was modified by calcination temperature and duration. CO oxidation and preferential CO oxidation reaction were studied on these catalysts at lambda = 2 (P-O2/P-CO) = 1. The CO oxidation reaction activation energy decreased with increasing particle size, consistent with previous reports. CO reaction orders exhibited no systematic change with respect to particle size, but a minor but systematic decrease in the CO oxidation reaction order was seen with respect to oxygen partial pressure with decreasing particle size, indicating higher selectivity toward PROX reactions at higher; on larger particles. On catalysts with 69 and 83% dispersions, the light-off curves were identical in hydrogen-free streams, whereas on the catalyst with higher dispersion, the light-off temperature was lower in the presence of hydrogen, indicating that the hydrogen oxidation reaction was more facile on catalysts with more defect sites. (c) 2006 Elsevier Inc. All rights reserved

Effect of helmet use on maxillofacial injuries due to bicycle and scooter accidents: a systematic literature review and meta-analysis

Maxillofacial injury is a common injury resulting from bicycle (including e-bike) and scooter accidents. With 80,000 admissions to emergency departments in 2019, bicycle accidents account for more than half of all traffic-related emergency department visits in the Netherlands. The United States reports approximately 130,000 injuries and 1000 fatalities related to cycling annually. This systematic review and meta-analysis was performed to examine the protective effect of helmets against maxillofacial injuries resulting from bicycle and scooter (including e-bike and e-scooter) accidents. After a systematic literature search, 14 studies were found to be eligible for this systematic review. Of these, 11 were included in the meta-analysis. None of the included studies focused on vehicles with motors (e-bikes and e-scooters); all focused only on non-motorized vehicles. All included studies were non-randomized, which could have led to bias in the pooled results. Data from the included studies were tested for heterogeneity using the binary random-effects model (DerSimonian-Laird method), and the odds ratio for the occurrence of maxillofacial injury in cyclists wearing a helmet versus those not wearing a helmet was calculated by random-effects meta-analysis. Patients who had worn a helmet suffered significantly fewer maxillofacial injuries than patients who had not, in bicycle accidents (odds ratio 0.682). In conclusion, wearing a helmet has a significant protective effect against maxillofacial injury, indicating the need for strict helmet legislation

The efficacy and clinical outcome of transjugular intrahepatic portosystemic shunts in the management of ectopic variceal bleeding: a multicenter retrospective study

status: publishe

Electrical Power Quality of Iron and Steel Industry in Turkey

Iron and Steel Industry has been growing increasingly in Turkey in the last decade. Today its electricity demand is nearly one tenth of the installed generation capability of 40 GW in the country. In this paper, power quality investigations based on the arc furnace installations of the iron and steel plants using field measurements according to the international standard IEC 61000-4-30 are documented. Inter-harmonies and voltage flicker problems occurring both at the common coupling points of those plants and at the are furnace and SVC systems of the plants themselves are determined with the use of GPS receiver synchronization modules attached to the mobile power quality measurement systems. It has been observed that flicker and interharmonic problems are dominant at the point of common couplings where arc furnace installations are supplied. Based on the field measurements obtained with collaborative work of five arc furnace plants, it is possible to say that contemporary SVC systems cause interharmonic amplification problems around the second harmonic and novel methods are required to solve this problem

Mobile Monitoring System to Take PQ Snapshots of Turkish Electricity Transmission System

This work is devoted to taking nationwide power quality (PQ) snapshots of the Turkish Electricity Transmission System, via field measurements carried out by application speck mobile monitoring equipment. This project is carried out as a subproject of the National Power Quality Project of Turkey, and is aimed at investigating the general status of electric power quality and reactive power flows in the Electricity Transmission System all over the country. Critical points will then be selected to place permanent PQ monitors, and to carry out troubleshooting projects on the system. This paper describes the mobile monitoring system established, and the methodology used to obtain power quality snapshots of the Turkish Electricity Transmission System. Some sample outputs of the mobile monitoring system are also given in the paper

Mobile monitoring system to take nationwide PQ measurements on electricity transmission systems

This paper describes mobile power quality monitoring systems developed to carry out extensive power quality (PQ) measurements nationwide, in addition to instrumentation and measurement technologies used in those systems. The developed systems have been used to measure the PQ of the Turkish Electricity Transmission System, which is among the largest transmission systems in Europe. To make trouble-shooting studies at the problematic measurement points in terms of PQ different measuring instruments and a wide range of PQ analysis methods from raw data acquisition to PQ event detection have been achieved depending on the nature of the problem, thanks to the flexible signal processing algorithms developed. Being an essential issue in the evaluation of PQ at various points of the electricity transmission network, time synchronization of mobile PQ monitoring systems has been applied using different techniques. Electromagnetic immunity of the system has been tested and reported. Based on the proposed instrumentation and measurement technologies, PQ of the 205 measurement points has been assessed all over the country. In order to exhibit the capabilities and usefulness of the mobile monitoring system developed, sample measurement results are given in the paper. Guidelines of instrumentation and measurement technologies are presented for other researchers who would like to build distributed PQ measurement systems

Neopterin and soluble CD14 levels as indicators of immune activation in cases with low anti-HCV reactivity and true HCV infection

Neopterin and soluble CD14 (sCD14) are detected at high levels in hepatitis C virus (HCV) infections. We aimed to evaluate the role of these plasma immune activation biomarkers, for the indirect assessment of immune activation status of patients with low anti-HCV reactivity and a HCV infection. Low anti-HCV reactivity group (LRG, n: 70), true positive HCV infection group (THG, 30) and healthy control group (HCG, 30) were analyzed in this study. We have used ELISA, HCV RIBA/LIA and HCV-RNA methods. Mean neopterin levels were significantly lower in LRG than THG (p 0.05). Mean sCD14 were significantly higher in LRG than THG and HCG (p <0.05, p <0.001). Values of 3.95 mu g/ml and 5.36 nmol/l for sCD14 and neopterin resulted in the maximum area under the receiver operating characteristic curves (ROC), which were 0.859 (95% CI, 0.745 to 0.935; <0.0001) and 0.788 (95% CI, 0.663 to 0.883; <0.0001), respectively. These cut-offs corresponded to a sensitivity of 73.3% and a specificity of 73.3% for neopterin and of 100% and 76.7% for sCD14. Our results suggest that a specific immunoactivation might be caused by true positive HCV infection. Due to the significant results sCD14 in LRG might be non-specifically affected by some underlying atypical immunohematological pathologies. Only neopterin might be used to exclude low anti-HCV reactivity from a true HCV infection. The use of neopterin but not sCD14 in combination with fourth-generation EIA/CMIA combo tests will be useful when nucleic acid tests are not available for screening blood donors at blood banks