Estimation of the Degree of Crystallinity of Partially Crystalline Polypropylenes Using 13C\text{}^{13}C NMR

The paper deals with a method for the estimation of the degree of crystallinity for partially-crystalline isotactic-polypropylenes (i-PP) using high-resolution solid-state $\text{}^{13}C$ NMR. For this purpose direct polarization $\text{}^{13}C$ MAS NMR spectra were measured for i-PP samples with different degrees of crystallinity at 98°C. The areas beneath the resonance lines in these spectra correspond to the number of carbons in particular functional groups, while the widths and shapes of the lines reflect the degree of crystallinity, crystalline modifications, distribution of chain conformations and the chain mobility. The $\text{}^{13}C$ MAS NMR spectra, measured using appropriate combination of delay time and high proton decoupling field, made it possible to detect only amorphous domains in the sample. This enabled identification of the lines associated with the amorphous domains in the complete $\text{}^{13}C$ MAS NMR spectra and provided sufficient information for reliable estimation of the degree of crystallinity. The heteronuclear Overhauser enhancement of the $\text{}^{13}C$ NMR signals due to short delay time was taken into account in our calculations

Cu3(tmen)3(tma)2(H2O)2Cu_3(tmen)_3(tma)_2(H_2O)_2 · 6.5H2O6.5H_2O - New S = 1/2 "Sawtooth" Chain?

The results of the investigation of magnetic susceptibility, magnetization and specific heat of $Cu_3(tmen)_3(tma)_2(H_2O)_2$ · $6.5H_2O$ (tmen = N,N,N',N'-tetramethylethane-1,2 diamine; $H_3$ tma = 1,3,5-benzenetricarboxylic acid) are reported. The spatial arrangement of magnetic Cu(II) ions and network of covalent bonds suggest that the studied material might be a representative of S = 1/2 sawtooth chain with moderate exchange coupling J/$k_{B}$. The investigation of the temperature dependence of susceptibility and magnetic field dependence of magnetization yielding J/$k_{B}$ ≈ - 0.63 K is consistent with the structural features. In addition, specific heat data reveal short-range correlations in milikelvin temperature range and indicate long-range ordering below 150 mK

Spin Glass State in S=3/2 Kagomé Antiferromagnet Co(N3)2(bpg)[(CH3)2(NCOH)]4/3Co(N_{3})_{2}(bpg)[(CH_{3})_{2}(NCOH)]_{4/3}

Specific heat, magnetic susceptibility and magnetization of $Co(N_{3})_{2}(bpg)[(CH_{3})_{2}(NCOH)]_{4/3}$, representing S=3/2 kagomé system are reported. Long-range ordering at 16 K was revealed, however, at lower temperatures slow spin dynamics is still found. The analysis of alternating susceptibility suggests the onset of glassy state. The study of the time dependence of magnetization revealed the existence of more relaxation channels with pronounced different relaxation times. The observed behaviour is consistent with the formation of topological spin glass in which relaxation is governed by both spin and chiral degrees of freedom

Research on brake fluids in personal cars

Na bezpieczeństwo w ruchu drogowym składa się wiele czynników, jednym z nich są sprawność techniczna pojazdu i dyspozycja kierowcy. W artykule przedstawiono badania jakości płynu hamulcowego zrealizowane na wybranej grupie samochodów osobowych. W przeprowadzonych badaniach określano temperaturę wrzenia płynu hamulcowego oraz procentową zawartość wody w płynie. Wykazano, że regularna wymiana płynu hamulcowego jest konieczna, a jej optymalna częstotliwość zależy nie tylko od konstrukcji układu, ale przede wszystkim od jakości płynu.The road traffic safety consists of many factors, one of them is technical performance of vehicle and disposition of driver. This paper presents research on the quality of the brake fluid conducted for a selected group of cars. The present study determined the boiling point of the brake fluid and the percentage of water in the fluid. It has been shown that regular replacement of brake fluid is required, and the optimum frequency depends not only on the design of the system, but also on the quality of the liquid

Operation Safety and Performance of Milling Cutters with Shank Style Holders of Tool Inserts

AbstractPaper introduces results related to the application of advanced milling cutters provided with shank style of tool insert holder. Design of prototypes of tool bodies is based on calculations of theoretical number of tool edges. Bodies of milling cutter include holes to mount tool insert holder while two types of insert shape as round and octagonal are used in milling cutter design. Based on measuring of cutting forces when milling planar surfaces, critical cutting conditions leading to the tool damage are identified and they are compared with commercial milling cutters. Applying cutting force data, operation safety is being studied concerning outer appearance of tool failure. Application of Finite Element Method is used to assess the critical spots leading to the insert holder failure. Maximum stress which brings about ductile fracture of shank style's insert holder has been found out by FEM modelling. Operation capability of tool inserts is compared with tool performance data. Surface roughness and short term tool wear testing was used as tool performance criteria to asses capability of new cutting tools in face milling operations. Surface quality produced by that kind of milling cutter is referred to as semi finishing and finishing cut. Advantages and limitations of that milling cutter innovation are discussed.Selection and/or peer-review under responsibility of the Branch Office of Slovak Metallurgical Society at Faculty of Metallurgy and Faculty of Mechanical Engineering, Technical University of Košice

Solid State 13C\text{}^{13}C NMR Study of Modified Polyhydroxybutyrate

Structural changes in polyhydroxybutyrate (PHB) brought about by addition of chain extender and/or plasticizer were studied using $\text{}^{13}C$ MAS NMR spectra, which were measured using the direct polarization technique at 30 and 98°C. Four resonances associated with the CO, CH, $CH_{2}$ and $CH_{3}$ groups of PHB were observed in the spectra. The $CH_{3}$ resonance appearing at 98°C shows splitting into two lines related to the crystalline and amorphous regions. Analysis of the $CH_{3}$ resonances made it possible to estimate the influence of applied modifications on crystallinity and distribution of conformations in amorphous and crystalline domains of PHB samples

Chosen aspects of safety of maritime transport in the Baltic Sea Basin

Gospodarka morska jest w szczególny sposób narażona na niebezpieczeństwo ze względu na środowisko swojej działalności. Zagrożenia te wynikają zarówno z działań umyślnych, jak i przypadkowych (warunki hydrometeorologiczne, mechaniczne itp.). Są to zagrożenia zależne i niezależne od człowieka np. środowiskowe, bezpieczeństwo zdrowia i życia ludzi, czy mienia. Pomimo podejmowania prób ograniczania ryzyka niebezpieczeństwa, niemożliwe jest jego całkowite wyeliminowanie. Pomocne mogą być wszelkiego rodzaju systemy bezpieczeństwa, alarmowe, ratunkowe, oraz działania legislacyjne i edukacyjne armatorów i załóg statków do działań obronnych. W artykule przedstawiono wybrane aspekty bezpieczeństwa transportu w basenie morza Bałtyckiego oraz podjęto próbę analizy stanu bezpieczeństwa na tym akwenie.The maritime economy is particularly exposed to danger due to the environment of its operations. These risks result from deliberate actions, as well as incidental (hydrometeorological conditions, mechanical, etc.). These are the threat dependent and independent of human eg. environmental, safety health and life of humans or belongings. In spite of attempts to limit the risk of danger, it is impossible to completely eliminate it. May be helpful here all kinds of security systems, alarm, emergency, legislative and educational of ship owners and crews to the defense activities. The article presents some aspects of the state of transportation safety in the Baltic Sea Basin as well as undertaken the attempt to analyze the security state of this sea area

The State of Road Transport Safety in Poland and Slovakia in 2004-2014

W artykule dokonano analizy porównawczej stanu bezpieczeństwa w ruchu drogowym w Polsce i na Słowacji na przestrzeni ostatnich dziesięciu lat. Analizę uzupełniono o prezentację danych odnośnie do programów i działań na rzecz poprawy bezpieczeństwa realizowanych w obu państwach. W pracy ukazano różnice w skuteczności prowadzonych działań i dokonano próby wyjaśnienia przyczyn ich występowania.In the article is performed the comparative analysis of the state of road safety in Poland and Slovakia over the past ten years. The analysis was complemented by a presentation of data concerning the programs and activities aimed at improving safety implemented in both countries. In the paper are the differences in the effectiveness of their actions were made the attempts to explain the reasons for their occurrence