Search results for "grain"
showing 10 items of 752 documents
The effect of Ag, Pb and Bi impurities on grain boundary sliding and intergranular decohesion in Copper
2016
We investigate the changes in grain boundary sliding (GBS) and intergranular decohesion in copper (Cu), due to the inclusion of bismuth (Bi), lead (Pb) and silver (Ag) substitutional impurity atoms at a $\Sigma$5 (0 1 2) symmetric tilt grain boundary (GB), using a first-principles concurrent multiscale approach. We first study the segregation behavior of the impurities by determining the impurity segregation energy in the vicinity of the GB. We find that the energetically preferred sites are on the GB plane. We investigate the intergranular decohesion of Cu by Bi and Pb impurities and compare this to the effect of Ag impurities by considering the work of separation, $W_s$ and the tensile st…
Kasvavan liikenteen kannattava kanava : Saimaan kanavan rahtiliikenne autonomian aikana
2013
Eficacia de la terapia manual articulatoria vertebral en pacientes con migraña
2019
La migraña es uno de los trastornos del sistema nervioso más comunes y se considera la tercera causa de incapacidad en el mundo en menores de 50 años. El tratamiento de la migraña mediante terapia manual articulatoria vertebral (TMAV) puede ser efectivo, sin embargo, existe más controversia que en otros tipos de cefaleas. El objetivo del presente estudio es valorar los cambios producidos tras la aplicación de TMAV en pacientes con migraña en cuanto a la intensidad del dolor y su impacto.44 participantes con una edad media de 39 años (desviación típica= 9.47) con migraña, fueron divididos en dos grupos de forma aleatoria: 1) grupo TMAV (n=22), 2) grupo control (n=22). Se realizaron dos evalu…
Modification of the Structure and Nano-Mechanical Properties of LiF Crystals Under Irradiation with Swift Heavy Ions
2011
The modifications of the structure and hardness of LiF crystals under high-fluence irradiation with MeV- and GeV-energy Au ions have been studied using nanoindentation and atomic force microscopy. The formation of ion-induced dislocations and bulk nanostructures consisting of grains with nanoscale dimensions (50 nm - 100 nm) has been observed. The structural modifications are accompanied by a strong ion-induced hardening which is related to dislocation impeding by assemblies of defect aggregates, dislocation loops of vacancy and interstitial types and grain boundaries. For MeV ions, the modifications are localized in a thin surface layer (few mm) where much higher density of deposited energ…
Study of phase transition in Bi3TiNbO9-BaBi2Nb2O9 ceramics
2016
Abstract The subject of the paper is lead free bismuth layer structure oxides (1-x)Bi3TiNbO9-xBaBi2Nb2O9 (x=0; 1; 2; 3 mol). The influence of Bi3TiNbO9/BaBi2Nb2O9 ratio on dielectric and structural properties was studied in a wide range of temperatures. Change in the ratio causes a decrease in the maximum value of dielectric permittivity and shifts the temperature of ε’max to low values, leading to linear decreasing of average grain size and linear increasing of ceramics density. These results indicate an augment of the packing degree and the participation of pores are significantly decreased with the increase of BaBi2Nb2O9 compound intake. Moreover, for 0.7Bi3TiNbO9-0.3BaBi2Nb2O9 ceramics …
Investigations of Latvian Illite/Kaolinite Clays Irradiated Under Action of Accelerated Electrons
2019
Natural clay is a perspective material for application as sorbents for wastewater treatment as well as for sorption of radionuclides, where the properties of the clays can be changed under influence of ionizing radiation. For application of Latvian illite/kaolinite clays for isotope sorption it is important to characterize the physic-chemical properties of pre-prepared air dried clays. Two fractions of the illite clays were selected. A fraction with grain size 100 μm (SiO2 content 60.9 ± 1.5 wt.%, specific surface area 35 m2/g) and a sand free fraction – 2 μm (SiO2 47.7 ± 1.9 wt.%, specific surface area 38 m2/g). Selected fractions were irradiated with accelerated electrons (5 MeV, ELU-4, S…
Impaired glutamatergic neurotransmission in migraine with aura? Evidence by an input-output curves transcranial magnetic stimulation study.
2011
Objective: An imbalance between activity of inhibitory and facilitatory intracortical circuits could play a central role in migraine etiology. We used input-output curves to achieve further information about intracortical excitability of motor cortex in migraine with aura. METHODS: Input-output curves were measured in the right abductor pollicis brevis muscle at rest in 12 patients suffering from migraine with aura and 8 healthy subjects. Stimuli were delivered at intensity ranging from 100% to 160% of resting motor threshold with 10-second inter-stimulus intervals. Seven patients were studied before and during treatment with levetiracetam. RESULTS: Results showed a greater motor-evoked pot…
La microstruttura di una "locked sand"
2009
Nella nota si riportano alcuni risultati sperimentali sul comportamento meccanico di una locked sand. Si descrive la microstruttura della sabbia sulla base di osservazioni al microscopio ottico e al SEM. Si descrivono in particolare i tipi di contatti intergranulari, che sono prevalentemente interpenetranti (concavo-convessi e suturati), gli indici grain contact e packing density caratterizzanti la struttura del materiale, e la loro influenza sul comportamento meccanico della sabbia. I risultati ottenuti sono confrontati con quelli di altre locked sands.
Effect of a Craniosacral Therapy Protocol in People with Migraine: A Randomized Controlled Trial
2022
Background: Migraine is a common neurological disorder, and it is the second leading cause of disability worldwide. Manual techniques based on physical therapy have been proposed to improve migraine aspects; however, further research is needed on their effectiveness. The aim of this study was to evaluate the effectiveness of a craniosacral therapy protocol on different features in migraine patients. Methods: Fifty individuals with migraine were randomly divided into two groups (n = 25 per group): (i) craniosacral therapy group (CTG), following a craniosacral therapy protocol, and (ii) sham control group (SCG), with a sham treatment. The analyzed variables were pain, migraine severity and fr…
Galvassāpju izplatība Latvijas Universitātes medicīnas studentu vidū
2022
Ievads: Galvassāpju traucējumi, galvenokārt primārie, tiek uzskatīti par nopietnām globālām veselības problēmām, kas izraisa ievērojamu invaliditātes slogu slimniekiem, lai arī paradoksālā kārtā, bieži tiek ignorēti un nenovērtēti. Cilvēki savos produktīvajos gados irvisvairāk skartā grupa, un to vidū ir arī studenti. Mērķis: Pētījuma mērķis bija apkopot Latvijas Universitātes medicīnas studentu galvassāpju epidemioloģiskos un klīniskos raksturojumus, lainoteiktu cefalģijas izplatību, novērtētu riska faktorus, provocējošos faktorus, galvassāpju ietekmi un to mazināšanu ar medikamentiem, kā arī noskaidrot iespējamos iemeslus, kādēļ pētāmā populācija izvairās no specializētas galvassāpju trau…