Studija promjena ispod obrađene površine i pridruženi fenomeni u zoni rezanja tijekom bušenja nehrđajućeg čelika s niskim sadržajem ugljika

This article presents the results of experiments that concerned the verification of machined surface conditions of workpieces from a new austenitic stainless steel with Extra Low Carbon (ELC) Cr22Ni9MoTi compared with stainless steels Cr18Ni8. The results of cutting zone evaluation under cutting speed 80 m/min, depth of cut 2,75 mm and feed 0,08 mm per rev., a definition of shear level angle Φ1. For Cr22Ni9MoTi steel Φ1 is 36° to 39°. The acquired results are interesting in that for the defined conditions we can achieve a quality outer surface after cutting with roughness parameters down to around 0,65 μm at cutting speed 80 m/min and feed 0.08 mm per rev.Rad prikazuje rezultate eksperimentalnog istraživanja koji se odnose na verifikaciju uvjeta strojne obrade radnih komada od austenitnog nehrđajućeg čelika sa posebno niskim sadržajem ugljika (ELC) Cr22Ni9MoTi u usporedbi sa nehrđajućim čelikom Cr18Ni8. Rezultati ocjene rezne površine kod brzine rezanja 80 m/min, dubine reza 2,75 mm i posmaka 0,08 mm po okretaju definiraju vrijednost smičnog kuta Φ1. Za čelik Cr22Ni9MoTi Φ1 je 36° do 39°. Prikupljeni rezultati su zanimljivi za definiranje uvjeta pod kojim se može postići kvaliteta hrapavosti vanjske površine nakon rezanja do oko 0,65 μm kod brzine rezanja 80 m/min i posmaka 0,08 mm po okretaju

Repeated bedside echocardiography in children with respiratory failure

<p>Abstract</p> <p>Background</p> <p>The aim of this study was to verify the benefits and limitations of repeated bedside echocardiographic examinations in children during mechanical ventilation. For the purposes of this study, we selected the data of over a time period from 2006 to 2010.</p> <p>Methods</p> <p>A total of 235 children, average age 3.21 (SD 1.32) years were included into the study and divided into etiopathogenic groups. High-risk groups comprised: Acute lung injury and acute respiratory distress syndrome (ALI/ARDS), return of spontaneous circulation after cardiopulmonary resuscitation (ROSC), bronchopulmonary dysplasia (BPD), cardiomyopathy (CMP) and cardiopulmonary disease (CPD). Transthoracic echocardiography was carried out during mechanical ventilation. The following data were collated for statistical evaluation: right and left ventricle myocardial performance indices (RV MPI; LV MPI), left ventricle shortening fraction (SF), cardiac output (CO), and the mitral valve ratio of peak velocity of early wave (E) to the peak velocity of active wave (A) as E/A ratio. The data was processed after a period of recovery, i.e. one hour after the introduction of invasive lines (time-1) and after 72 hours of comprehensive treatment (time-2). The overall development of parameters over time was compared within groups and between groups using the distribution-free Wilcoxons and two-way ANOVA tests.</p> <p>Results</p> <p>A total of 870 echocardiographic examinations were performed. At time-1 higher average values of RV MPI (0.34, SD 0.01 vs. 0.21, SD 0.01; p < 0.001) were found in all groups compared with reference values. Left ventricular load in the high-risk groups was expressed by a higher LV MPI (0.39, SD 0.13 vs. 0.29, SD 0.02; p < 0.01) and lower E/A ratio (0.95, SD 0.36 vs. 1.36, SD 0.64; p < 0.001), SF (0.37, SD 0.11 vs. 0.47, SD 0.02; p < 0.01) and CO (1.95, SD 0.37 vs. 2.94, SD 1.03; p < 0.01). At time-2 RV MPI were lower (0.25, SD 0.02 vs. 0.34, SD 0.01; p < 0.001), but remained higher compared with reference values (0.25, SD 0.02 vs. 0.21, SD 0.01; p < 0.05). Other parameters in high-risk groups were improved, but remained insignificantly different compared with reference values.</p> <p>Conclusion</p> <p>Echocardiography complements standard monitoring of valuable information regarding cardiac load in real time. Chest excursion during mechanical ventilation does not reduce the quality of the acquired data.</p

Spectral characteristics of the newborn rhesus macaque EEG reflect functional cortical activity

Brain electrical activity is one means of assessing neural development in awake, reactive infants. The development of the electroencephalogram (EEG) in the first week of infant rhesus macaque life is poorly understood though recent work has demonstrated the utility of using this measure to assess neural responses to biologically meaningful stimuli. Here we report on the emergence of EEG rhythms in one-week-old infant rhesus macaques under both light and dark conditions. Our data show that the 5 – 7 Hz frequency band responds reliably to changes in illumination. As well, we found EEG in higher frequencies (12 – 20 Hz) that significantly increase between dark and light conditions similar to the increase in the beta band of humans during cognitive tasks. These findings demonstrate similarities between infant human and infant monkey EEG and suggest approaches for future translational research in developmental psychobiology