Nonlinearity effects in wave propagation in multicomponent Bose-Einstein condensates

We consider a spinor Bose-Einstein condensate in its polar ground state. We analyze magnetization waves of a finite amplitude and show that their nonlinear coupling to density waves dramatically changes the dependence of the frequency on the wave number. On the contrary, the density wave propagation is much less modified by nonlinearity effects. A similar phenomenon in a miscible two-component condensate is also studied.     

Fast gas chromatography for pesticide residues analysis using analyte protectants

Fast GC-MS with narrow-bore columns combined with effective sample preparation technique (QuEChERS method) was used for evaluation of various calibration approaches in pesticide residues analysis. In order to compare the performance of analyte protectants (APs) with matrix-matched standards calibration curves of selected pesticides were searched in terms of linearity of responses, repeatability of measurements and reached limit of quantifications utilizing the following calibration standards in the concentration range 1-500 ng mL(-1)(the equivalent sample concentration 1-500 microg kg(-1)): in neat solvent (acetonitrile) with/without addition of APs, matrix-matched standards with/without addition of APs. For APs results are in a good agreement with matrix-matched standards. To evaluate errors of determination of concentration synthetic samples at concentration level of pesticides 50 ng mL(-1) (50 microg kg(-1)) were analyzed and quantified using the above given standards. For less troublesome pesticides very good estimation of concentration was obtained utilizing APs, while for more troublesome pesticides such as methidathion, malathion, phosalone and deltamethrin significant overestimation reaching up to 80% occurred. According to presented results APs can be advantegously used for "easy" pesticides determination. For "difficult" pesticides an alternative calibration approach is required for samples potentially violating MRLs. An example of real sample measurement is shown. In this paper also the use of internal standards (triphenylphosphate (TPP) and heptachlor (HEPT)) for peak areas normalization is discussed in terms of repeatability of measurements and quantitative data obtained. TPP normalization provided slightly better results than the use of absolute peak areas measurements on the contrary to HEPT.     

Comparison of sample preparation methods combined with fast gas chromatography-mass spectrometry for ultratrace analysis of pesticide residues in baby food

Four sample preparation techniques were compared for the ultratrace analysis of pesticide residues in baby food: (a) modified Schenck's method based on ACN extraction with SPE cleaning; (b) quick, easy, cheap, effective, rugged, and safe (QuEChERS) method based on ACN extraction and dispersive SPE; (c) modified QuEChERS method which utilizes column-based SPE instead of dispersive SPE; and (d) matrix solid phase dispersion (MSPD). The methods were combined with fast gas chromatographic-mass spectrometric analysis. The effectiveness of clean-up of the final extract was determined by comparison of the chromatograms obtained. Time consumption, laboriousness, demands on glassware and working place, and consumption of chemicals, especially solvents, increase in the following order QuEChERS < modified QuEChERS < MSPD < modified Schenck's method. All methods offer satisfactory analytical characteristics at the concentration levels of 5, 10, and 100 microg/kg in terms of recoveries and repeatability. Recoveries obtained for the modified QuEChERS method were lower than for the original QuEChERS. In general the best LOQs were obtained for the modified Schenck's method. Modified QuEChERS method provides 21-72% better LOQs than the original method.     

Decomposition of peroxides of oxidised polypropylene studied by the chemiluminescence method

It was found that the initial increase in light emission from pre-oxidised polypropylene, measured in a nitrogen atmosphere, is due to decomposition of hydroperoxides in the system. Decomposition is a bimolecular reaction with the probable participation of chemisorbed oxygen. A new initiation reaction step is proposed which contributes to the deterioration of the polymer properties in the induction period of oxidation.     

Accurate lifetime measurements for the noble gases by the electron beam alignment technique

Rotational rainbow scattering has been measured in the systems K- and Rb-CO₂ at collision energies 0.17≦E≦0.56 eV and CMS angles 110°≦?≦170°. The ellipsoidal hard shell anisotropy of the normal (repulsive) potentials is evaluated to be (c?a)=0.67Å in K?CO₂, (c?a)=0.63Å in Rb?CO₂, averaged over a slight energy dependence. Below an apparent activation thresholdE _a?0.23 eV, nearly equal in both systems, the scattering largely conforms to that of diatomic molecules, indicating linear, rigid rotor type behaviour as the dominant collisional response of triatomic CO₂. AboveE _a characteristic, eventually drastic distortions set in. They are probably caused by intermediary charge transfer which activates a complex, coupled vibrational, rotational motion inM ⁺-CO ₂ ^? , altering the outcome of the collisions altogether. The simple model of a partially absorptive, hard shell is used to find that some gross features of the distortions are consistent with distinct properties of the acceptingelectronic orbital 6a ₁ in CO ₂ ^? .     

Difference method of evaluation of dynamic integral thermogravimetric curves in decomposition of polypropylene

A new differential method of evaluating integral thermogravimetric records of the formation of volatile products during the degradation of polypropylene in air is presented. The method, applied to 0–100% conversion of the polymer to volatile products, may distinguish the initial presence of low molecular compounds in the polymer, as well as changes in the mechanism of degradation of the material.

---

Zusammenfassung Es wird eine neue differentielle Methode zur Auswertung der die Bildung von flüchtigen Produkten während der Zersetzung von Polypropylen in Luft widerspiegelnden integralen thermogravimetrischen Kurven dargelegt. Mit der im Bereich 0–100% Konversion von Polymer zu flüchtigen Produkten anwendbaren Methode können sowohl die Anwesenheit niedermolekularer Verbindungen im Polymer als auch Veränderungen im Abbaumechanismus des Materials erkannt werden.

---

, . , 0–100%- , , .

     

Fast gas chromatography with solid phase extraction clean-up for ultratrace analysis of pesticide residues in baby food

A sample preparation method based on single solvent phase extraction and solid-phase extraction (SPE-NH2) clean-up is studied in combination with fast capillary gas chromatography (GC) to determine 18 selected pesticides belonging to various chemical classes in apples, the common raw material for baby food production and baby food, at the concentration level < or = 10 microg/kg maximum residual limit (MRL). Possibilities of mass spectrometry (MS) detector and electron capture detector (ECD) in fast gas chromatography (GC) of samples with complex matrice at ultra trace levels of pesticide residues were studied and compared. MS detection in single ion monitoring (SIM) mode provided higher selectivity compared to ECD. Optimisation of extraction as well as the simplifying of the whole process of sample preparation was carried out. Recoveries obtained at concentration level of 5 microg/kg (the required value for limit of quantification (LOQ) in baby food) were >90%, except of dimethoate (77.7%) and captan (46.4%) with MS detection. The obtained LOQs were at least 1 order lower than 5 microg/kg for the majority of compounds. The repeatability of gas chromatography-mass spectrometry (GC-MS) measurements of the matrix matched standards expressed as relative standard deviation was <11% except of captan and cypermethrin.     

The dependence of the properties of liquid crystals on the film thickness and surface quality of capillary columns

Summary Glass capillary columns were prepared from non-deactivated and deactivated glass and coated with (2-methyl-4-[trans-4-n-propyl-cyclohexylcarbonyloxy]-benzoic acid-[4-n-heptyloxy-phenylester]) as the liqud phase, in different film thicknesses. The columns were tested using substances of different structures and polarities. It was verified that the capacity factors, retention indices and selectivity significantly depend on the thickness of the liquid crystalline stationary phase film and the quality of the tube, particularly in the case of columns with thin films. Trasition temperatures (melting and clearing point) of the liquid crystal are also dependent on these two factors.Dedicated to Professor J. F. K. Huber on the occasion of the his 60th birthday.     

The Progress of Ageing of Lignin-containing Paper Induced by Light and its Relation to Chemiluminescence – Temperature Runs

Lignin-containing papers from different sources and of different age were irradiated by the visible light and the progress of the degradation reaction was followed by non-isothermal chemiluminescence method. Kinetic data obtained for papers degraded in oxygen were compared with double fold endurance test and carbonyl groups concentration. The effect of lignin on degradation of cellulose after deacidification treatment of the paper by methoxymagnesium methylcarbonate (MMMC) was ascertained and a mechanism of co-oxidation of lignin and cellulose in originally alkaline conditions was outlined.     

VSCPT subrecoil laser cooling of atoms with a non-degenerated (J=0) ground state

We present new investigations on a five-level laser cooling scheme which can be used for subrecoil cooling of the group of even-even isotopes. System dynamics and the temporal evolution of the atomic momentum distribution are examined numerically in the case of ²⁰⁰Hg. We prove important features, e.g. constant efficiency at long interaction times as well as the influence of relaxation of coherences on the cooling process.