To what extent can mutual shifting of folded carbonaceous walls in slit-like pores affect their adsorption properties?

We have performed systematic Monte Carlo studies on the influence of shifting the walls in slit-like systems constructed from folded graphene sheets on their adsorption properties. Specifically, we have analysed the effect on the mechanism of argon adsorption (T = 87 K) and on adsorption and separation of three binary gas mixtures: CO2/N2, CO2/CH4 and CH4/N2 (T = 298 K). The effects of the changes in interlayer distance were also determined. We show that folding of the walls significantly improves the adsorption and separation properties in comparison to ideal slit-like systems. Moreover, we demonstrate that mutual shift of sheets (for small interlayer distances) causes the appearance of small pores between opposite bulges. This causes an increase in vapour adsorption at low pressures. Due to overlapping of interactions with opposite walls causing an increase in adsorption energy, the mutual shift of sheets is also connected with the rise in efficiency of mixtures separation. The effects connected with sheet orientation vanish as the interlayer distance increases

Late-onset bloodstream infections of Very-Low-Birth-Weight infants: data from the Polish Neonatology Surveillance Network in 2009–2011

BACKGROUND: Late-Onset Bloodstream Infections (LO-BSI) continue to be one of the most important complications associated with hospitalization of infants born with very low birth weight (VLBW). The aims of this study were to assess the epidemiology of LO-BSI together with the risk factors and the distribution of causative pathogens at six Polish neonatal intensive care units that participated in the Polish Neonatology Surveillance Network from January 1, 2009 to December 31, 2011. METHODS: The surveillance covered 1,695 infants whose birth weights were <1501 grams (VLBW) in whom LO-BSI was diagnosed >72 hours after delivery. Case LO-BSI patients were defined according to NeoKISS. RESULTS: Four hundred twenty seven episodes of LO-BSI were diagnosed with a frequency of 25.3% and an incidence density of 6.7/1000 patient-days (pds). Results of our multivariate analysis demonstrated that surgical procedures and lower gestational age were significantly associated with the risk of LO-BSI. Intravascular catheters were used in infants with LO-BSI significantly more frequently and/or for longer duration: Central venous cathters (CVC) (OR 1.29) and Peripheral venous catheters (PVC) (OR 2.8), as well as, the total duration of total parenteral nutrition (13 vs. 29 days; OR 1.81). Occurrence of LO-BSI was significantly associated with increased the length of mechanical ventilation (MV) (OR 2.65) or the continuous positive airway pressure (CPAP) (OR 2.51), as well as, the duration of antibiotic use (OR 2.98). The occurrence of more than one infection was observed frequently (OR 9.2) with VLBW with LO-BSI. Microorganisms isolated in infants with LO-BSI were dominated by Gram-positive cocci, and predominantly by coagulase-negative staphylococci (62.5%). CONCLUSIONS: Independent risk factor for LO-BSI in VLBV infants are: low gestational age and requirement for surgery. The incidence rates of LO-BSI especially CVC-BSI were higher in the Polish NICUs surveillance than those of other national networks, similar to the central- and peripheral utilization ratio

Mechanical thrombectomy in acute stroke – Five years of experience in Poland

Objectives Mechanical thrombectomy (MT) is not reimbursed by the Polish public health system. We present a description of 5 years of experience with MT in acute stroke in Comprehensive Stroke Centers (CSCs) in Poland. Methods and results We retrospectively analyzed the results of a structured questionnaire from 23 out of 25 identified CSCs and 22 data sets that include 61 clinical, radiological and outcome measures. Results Most of the CSCs (74%) were founded at University Hospitals and most (65.2%) work round the clock. In 78.3% of them, the working teams are composed of neurologists and neuro-radiologists. All CSCs perform CT and angio-CT before MT. In total 586 patients were subjected to MT and data from 531 of them were analyzed. Mean time laps from stroke onset to groin puncture was 250±99min. 90.3% of the studied patients had MT within 6h from stroke onset; 59.3% of them were treated with IV rt-PA prior to MT; 15.1% had IA rt-PA during MT and 4.7% – emergent stenting of a large vessel. M1 of MCA was occluded in 47.8% of cases. The Solitaire device was used in 53% of cases. Successful recanalization (TICI2b–TICI3) was achieved in 64.6% of cases and 53.4% of patients did not experience hemorrhagic transformation. Clinical improvement on discharge was noticed in 53.7% of cases, futile recanalization – in 30.7%, mRS of 0–2 – in 31.4% and mRS of 6 in 22% of cases. Conclusion Our results can help harmonize standards for MT in Poland according to international guidelines

Nitration and reduction route to surface groups of mesoporous carbons obtained from sucrose and phloroglucinol/formaldehyde precursors

Mesoporous ordered carbons were obtained from two precursors, sucrose and phloroglucinol/formaldehyde, using a hard-template and a soft-template method, respectively. The surface of the materials was modified with the –NH2 groups via nitration and subsequent reduction of the resulting –NO2 groups. The modified carbon materials were investigated by elemental analysis, Boehm titration, nitrogen sorption, XRD, TEM, thermal analysis including TPD, as well as XPS and Raman spectroscopy. Apart from the –NO2 groups, the nitration step resulted in formation of the oxygen-rich surface species, the concentration of which decreased after reduction. This concerned especially the carboxylic groups, a part of which transformed into the amino acetate type of species. The sucrose-based method resulted in the materials with more abounding acidic groups then in the case of the phloroglucinol-based route. The number of the acidic groups decreased after the nitration in the following order: CMK-1 > CMK-3 >> CMK-8. On the contrary, the resistance of the carbon structures to the nitration/reduction processes conformed to the order of CMC-1 > CMK-3 >> CMK-1 ∼ CMK-8. The nitrogen content after the amination step exceeded slightly 2 wt.%. Such surface modifications provided attachment of the TCPP ligands, the amount of which ranged between ca. 30–60 wt.%

Nanoscale Water Contact Angle on Polytetrafluoroethylene Surfaces Characterized by Molecular Dynamics–Atomic Force Microscopy Imaging

The aim of this study is to link polytetrafluoroethylene (PTFE) surface characteristics with its wetting properties in the nanoscale. To do this using molecular dynamics (MD) simulation, three series of rough PTFE surfaces were generated by annealing and compressing and next characterized by the application of the MD version of the atomic force microscopy (AFM) method. The values of specific surface areas were additionally calculated. The TIP4P/2005 water model was used to study the wetting properties of obtained PTFE samples. The simulated water contact angle (WCA) value for the most flat (but slightly rough) sample having PTFE density is equal to 106.94°, and it is close to the value suggested for a perfect PTFE surface on the basis of experimental results. Also, the changes in the WCA with PTFE compression are in the same range as experimentally reported. The obtained MD simulation results make it possible to link, for the first time, the WCA values with the surface MD–AFM root-mean-square roughness and with the PTFE density. Finally, we show that for PTFE wetting in the nanoscale, the line tension is negligible and the Bormashenko’s equation reduces to the Cassie–Baxter (CB) model. In fact, our simulation results are close to the CB mechanism