Outline of CHN Elementary and CN Environmental Analysis

Wydrukowano z dostarczonych Wydawnictwu UŁ gotowych materiałówA review on the CHN analysis of organic compounds and the CN environmental analysis is described. The review contains outline of the evolutionary development of elementary analysis, since Gay-Lussac, Dumas and Liebig era until a present slate analysis, with computer controlled, fully automated analyzers. Physical principles of high temperature and low temperature combustions are discussed. Technical foundations on conjunctions of the high temperature combustion with chromatographic separations of the ultimate combustion products of organic samples, is delineated. Commercially available elemental analyzers are compared and their construction and operating principles are described. The basic methods of determination of environmental carbon and nitrogen are discussed. The representative analyzers for environmental carbon and nitrogen analysis are presented and their operating principles are described.Zadanie pt. Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki nr 885/P-DUN/2014 zostało dofinansowane ze środków MNiSW w ramach działalności upowszechniającej naukę

Analysis of Organophosphorus Compounds. 1. Application of Iodine-Azide Reaction for Detection of Thiophosphoorganic Compounds in Thin-Layer Chromatography

Wydrukowano z dostarczonych Wydawnictwu UŁ gotowych materiałówZadanie pt. Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki nr 885/P-DUN/2014 zostało dofinansowane ze środków MNiSW w ramach działalności upowszechniającej naukę

Prefektura annony w okresie flawijskim. Uwagi wstępne

The praefectus annonae was responsible for the supply of grain to Rome, which is one of maid food products of the population of the Roman Empire. The office praefectus annonae was created by Augustus, the emperors of flavian dynasty filled it regularly. In equestrian cursus honorum this function has really great importance, it was one of the main equestrian offices. The office praefectus annonae is the intermediate post between the function praefectus vigilum and praefectus Aegypti, it could crown the career of equites or be an indirect element of the administrative career

The δ-phase of SrTeO3 at 780 K1

As part of a structural investigation of strontium tellurate(IV) (STO), SrTeO3, with particular emphasis on the crystal chemistry and phase transitions, the structure of the δ-phase has been determined at 780 K using a single-crystal analysis. Both structural and non-linear optical measurements indicate that STO undergoes a γ→δ second-order ferroelectric phase transition at 633 K from the C2 (γ) to the C2/m (δ) modification. Systematic differences between the similar γ- and δ-phase structures were determined and it was found that this phase transformation can be described by a displacive mechanism

Piezoelectric properties of Bi₂TeO₅ single crystals

This paper is devoted to the measurement results of piezoelectric, dielectric and elastic tensor components in the temperature range between 20 °C and 400 °C. It was revealed that excitation resonance and antiresonance signals were possible without preliminary sample polarizing. Besides, the sound velocities measured along the main axes by echo-pulse method at room temperature are presented.У роботi наведенi результати вимiрювань компонент п’єзоелектричних, дiелектричних та пружних тензорiв у діапазонi температур 20– 400 °C. Виявлено, що збудження сигналiв резонансу та антирезонансу можливе без попередньої поляризацiї зразка. Луна-iмпульсним методом отримано значення швидкостi звуку вздовж головних кристалографiчних осей при кiмнатнiй температурi

Ising-type behaviour of critical properties in weak ferroelectric Li₂Ge₇O₁₅

The dielectric constant ε and electron spin resonance spectra of Mn²⁺ ions have been studied in the range of the ferroelectric phase transition in Li₂Ge₇O₁₅ single crystals. Analysis of the experimental data permits one to estimate the critical exponents of dielectric susceptibility γ ≅ 1.25, order parameter β ≅ 0.32 and correlation length ν ≅ 0.63. The values of the critical exponents determined in a fairly broad temperature interval around Tc, are consistent with the theoretical predictions of the Ising model with a one-component non-polar ordering coordinate.Дiелектрична проникнiсть ε та спектри ЕПР iонiв Mn²⁺ дослiдженi в околi сегнетоелектричного фазового переходу у кристалах Li₂Ge₇O₁₅. Аналiз експериментальних даних дозволив оцiнити критичнi iндекси дiелектричної сприйнятливостi γ ≅ 1.25, параметра порядку β ≅ 0.32 i кореляцiйної довжини ν ≅ 0.63. Величини критичних iндексiв, обчисленi у досить широкому iнтервалi температур поблизу Tc, узгоджуються з теоретичними показниками моделi Iзiнга для однокомпонентного неполярного параметра порядку

Effects of process parameters on structure and properties of melt-blown poly(lactic acid) nonwovens for skin regeneration

Skin regeneration requires a three-dimensional (3D) scaffold for cell adhesion, growth and proliferation. A type of the scaffold offering a 3D structure is a nonwoven material produced via a melt-blown technique. Process parameters of this technique can be adapted to improve the cellular response. Polylactic acid (PLA) was used to produce a nonwoven scaffold by a melt-blown technique. The key process parameters, i.e., the head and air temperature, were changed in the range from 180–270 °C to obtain eight different materials (MB1–MB8). The relationships between the process parameters, morphology, porosity, thermal properties and the cellular response were explored in this study. The mean fiber diameters ranged from 3 to 120 µm. The average material roughness values were between 47 and 160 µm, whereas the pore diameters ranged from 5 to 400 µm. The calorimetry thermograms revealed a correlation between the temperature parameters and crystallization. The response of keratinocytes and macrophages exhibited a higher cell viability on thicker fibers. The cell-scaffold interaction was observed via SEM after 7 days. This result proved that the features of melt-blown nonwoven scaffolds depended on the processing parameters, such as head temperature and air temperature. Thanks to examinations, the most suitable scaffolds for skin tissue regeneration were selected

Rapid in situ assessment of radiocesium wood contamination using field gamma-ray spectroscopy to optimise felling

The Chernobyl nuclear power meltdown that took place in 1986 has left a radioactive contamination legacy that currently severely limits the economic potential of impacted regions including the Polessie State Radioecology Reserve in Southern Belarus. Extensive areas of forested land could potentially become economically viable for firewood and building materials if radioactive contamination, notably 137Cs, could be characterised faster, whilst closely adhering to regulatory limits. Currently, laboursome tree coring and unreliable transfer factors derived from limited soil sampling data are routinely employed in felling decision making, which has financial repercussions owed to the large amounts of waste produced and unnecessary transportation costs. In this study, it is demonstrated that a combination of targeted mobile gamma-ray spectrometry and a newly developed, lead shielded, in situ gamma-ray spectrometry method can significantly speed up the process of characterisation of 137Cs wood activity in the field. For the in situ method, Monte Carlo calibration routines were developed alongside spectral processing procedures to unfold spectra collected in the field allowing for separation of ground and tree spectral components. Isolated contributions from the tree could then be converted to activity. The method was validated at a test facility and then demonstrated at three separate sites with differing contamination levels. This technique showed that single trees could be measured within approximately 20% of the activity compared to conventional tree core data. However, some discrepancies were found which were attributed to under sampling using the tree corer and low count rates at the lowest activity site, prompting the need for further data collection to optimise the method. It was concluded that this real-time approach could be a valuable tool for management of contaminated forested areas, releasing valuable timber and ultimately reducing the risk associated with living and working in these areas