Extracellular glutamate accumulates only in final, ischemic stage of progressive epidural mass lesion in cats

Epidural mass lesions may cause ischemia due to progressive intracranial hypertension. In order to 1) investigate the impact of intracranial pressure (ICP) on accumulation of neuroactive substances, and 2) test the significance of neurochemical monitoring for early prediction of fatal outcome, we gradually raised ICP in cats by inflation of an epidural balloon: We assessed extracellular substrate alterations in the contralateral cortex in relation to changes of ICP, cerebral perfusion pressure (CPP) and mean arterial blood pressure (MABP). In a complementary experiment, regional cerebral blood flow was assessed by sequential positron emission tomography (PET).peer-reviewe

Comparison of Periodic Flow Fields in a Radial Pump among CFD, PIV, and LDV Results

The interaction between the impeller and the diffuser is considered to have a strong influence on the unsteady flow in radial pumps. In this paper, the unsteady flow in a low specific speed radial diffuser pump has been simulated by the CFD code CFX-10. Both Particle Image Velocimetry (PIV) and Laser Doppler Velocimetry (LDV) measurements have been conducted to validate the CFD results. Both the phase-averaged velocity fields and the turbulence fields obtained from different methods are presented and compared, in order to enhance the understanding of the unsteady flow caused by the relative motion between the rotating impeller and the stationary diffuser. The comparison of the results shows that PIV and LDV give nearly the same phase-averaged velocity fields, but LDV predicts the turbulence much clearer and better than PIV. CFD underestimates the turbulence level in the whole region compared with PIV and LDV but gives the same trend

Acid-Labile Traceless Click Linker for Protein Transduction

Intracellular delivery of active proteins presents an interesting approach in research and therapy. We created a protein transduction shuttle based on a new traceless click linker that combines the advantages of click reactions with implementation of reversible pH-sensitive bonds. The azidomethyl-methylmaleic anhydride (AzMMMan) linker was found compatible with different click chemistries, demonstrated in bioreversible protein modification with dyes, polyethylene glycol, or a transduction carrier. Linkages were stable at physiological pH but reversible at the mild acidic pH of endosomes or lysosomes. We show that pH-reversible attachment of a defined endosome-destabilizing three-arm oligo(ethane amino)amide carrier generates an effective shuttle for protein delivery. The cargo protein nlsEGFP, when coupled via the traceless AzMMMan linker, experiences efficient cellular uptake and endosomal escape into the cytosol, followed by import into the nucleus. In contrast, irreversible linkage to the same shuttle hampers nuclear delivery of nlsEGFP which after uptake remains trapped in the cytosol. Successful intracellular delivery of bioactive ß-galactosidase as a model enzyme was also demonstrated using the pH-controlled shuttle system

Microseismic joint location and anisotropic velocity inversion for hydraulic fracturing in a tight Bakken reservoir

To improve the accuracy of microseismic event locations, we developed a new inversion method with double-difference constraints for determining the hypocenters and the anisotropic velocity model for unconventional reservoirs. We applied this method to a microseismic data set monitoring a Middle Bakken completion in the Beaver Lodge area of North Dakota. Geophone arrays in four observation wells improved the ray coverage for the velocity inversion. Using an accurate anisotropic velocity model is important to correctly assess the height growth of the hydraulically induced fractures in the Middle Bakken. Our results showed that (1) moderate-to-strong anisotropy exists in all studied sedimentary layers, especially in the Upper and Lower Bakken shale formations, where the Thomsen parameters (ϵ and γ) can be greater than 0.4, (2) all the events selected for high signal-to-noise ratio and used for the joint velocity inversion are located in the Bakken and overlying Lodgepole formations, i.e., no events are detected in the Three Forks formation below the Bakken, and (3) more than half of the strong events are in two clusters at approximately 100 and 150 m above the Middle Bakken. Reoccurrence of strong, closely clustered events suggested activation of natural fractures or faults in the Lodgepole formation. The sensitivity analysis for the inversion results showed that the relative uncertainty in parameter δ is larger than other anisotropy parameters. The microseismic event locations and the anisotropic velocity model are validated by comparing synthetic and observed seismic waveforms and by S-wave splitting.Shell Oil Compan

Parametric study of a novel groove design for dry gas seals

This paper presents a performance analysis of a novel bidirectional groove design for dry gas seals. The scope of analysis includes the impact of important groove design parameters on the dry gas seal performance. The leakage flow and the axial stiffness and damping force coefficients are taken into account for performance assessment. For varying geometry the pressure field in the lubrication gap of the application is estimated. Based on these pressure fields the performance parameters are calculated. The utilized method to predict the fluid flow through the lubrication gap is founded on the Reynolds theory of lubrication. This two dimensional approach is based on the assumptions of a laminar viscous flow field with isothermal conditions and takes aerostatic as well as aerodynamic effects into account. The 2D approach is solved by a finite difference approximation. The aim of the contribution is to recommend geometrical parameters to ensure large static stiffness and damping force coefficients while still allowing for low seal leakage rates.Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016