Growth and optical investigations of high quality individual CdTe/(Cd,Mg)Te core/shell nanowires.

CdTe nanowires with the average diameter of only 40 nm coated with (Cd,Mg)Te shells are grown using Au-catalyzed vapor-liquid-solid growth mechanism in a system for molecular beam epitaxy. High optical quality of individual nanowires is revealed by means of low temperature cathodoluminescence and micro-luminescence. It is found that, the optical emission spectrum consists mostly of the near band edge emission without any significant contribution of defect related luminescence. Moreover, the importance of surface passivation with (Cd,Mg)Te coating shells is demonstrated.

Comparison of magneto-optical properties of various excitonic complexes in CdTe and CdSe self-assembled quantum dots.

We present a comparative study of two self-assembled quantum dot (QD) systems based on II-VI compounds: CdTe/ZnTe and CdSe/ZnSe. Using magneto-optical techniques we investigated a large population of individual QDs. The systematic photoluminescence studies of emission lines related to the recombination of neutral exciton X, biexciton XX, and singly charged excitons (X(+), X(-)) allowed us to determine average parameters describing CdTe QDs (CdSe QDs): X-XX transition energy difference 12 meV (24 meV); fine-structure splitting δ1=0.14 meV (δ1=0.47 meV); g-factor g = 2.12 (g = 1.71); diamagnetic shift γ=2.5 µeV T(-2) (γ =1.3 µeV T(-2)). We find also statistically significant correlations between various parameters describing internal structure of excitonic complexes.

Coexistence of optically active radial and axial CdTe insertions in single ZnTe nanowire.

We report on the growth, cathodoluminescence and micro-photoluminescence of individual radial and axial CdTe insertions in ZnTe nanowires. In particular, the cathodoluminescence technique is used to determine the position of each emitting object inside the nanowire. It is demonstrated that depending on the CdTe deposition temperature, one can obtain an emission either from axial CdTe insertions only, or from both, radial and axial heterostructures, simultaneously. At 350 °C CdTe grows only axially, whereas at 310 °C and 290 °C, there is also significant deposition on the nanowire sidewalls resulting in radial core/shell heterostructures. The presence of Cd atoms on the sidewalls is confirmed by energy dispersive X-ray spectroscopy. Micro-photoluminescence study reveals a strong linear polarization of the emission from both types of heterostructures in the direction along the nanowire axis.

[Effect of water contamination with surface active substances and plant protecting agents on aquatic organisms]. / Wplyw zanieczyszczenia wód substancjami powierzchniowo-czynnymi i srodkami ochrony roslin na organizmy wodne.

The purpose of the study was establishing in what degree the presence of surface-active substances affects the influence of herbicides present in surface waters on aquatic organisms. The study was carried out under laboratory conditions using as herbicides promethrin (triazine group) and dichlorophenoxy-acetate sodium (2,4 D), and detergents - sodium alkylsuphonate ABS and non-ionic detergent Rokafenol N8P7. The effect of these substances was studied on the test organisms from own cultures - Daphnia magna Straus, larvae of insects Chironomus plumosus L, and young fish Lebistes reticulatus. The study showed that promethrin was the herbicide with stronger action on the studied organisms than 2,4 D. The presence of single detergents and their mixtures increased promethrin effects by 10-13% on the testes invertebrates even in concentrations permitted in surface waters. The toxic effect of the herbicide 2,4 D was potentiated by detergents in much higher concentrations, exceeding the permitted values. Contamination of surface waters with detergents may endanger the trophic chain of aquatic biocenoses.

[Occurrence of aquatic organisms in water pipes and the resulting problems with drinking water disinfection]. / Wystepowanie organizmów wodnych w wodociagach i wynikajace stad problemy dezynfekcji wody do picia. Czesc I.

The present text is the first part of a paper aimed at specification of the requirements ensuring effective disinfection of drinking water. The discussed health hazards result not only from the presence of pathogenic microorganisms in water, but also from the occurrence of micro- and macroscopic plant and animal organisms. It was shown that while the traditional method for water treatment and disinfection reduces the number of these organisms, it fails to eliminate them completely, particularly in the case of tap water intake from shore intakes of surface waters.

Identification of interleukin-1 in normal human lymph derived from skin.

Interleukin 1 was isolated from human lymph drained from normal skin. The lymph was separated by gel filtration chromatography on Spherogel TSK SW 2000 column. IL-1 activity was found in three fractions: greater than 70 kD, 13-16 kD and 5-5.5 kD. Additionally a slight IL-1 activity was found in the 36-40 kD fraction. When exogenous IL-1 was added to the lymph inhibitory activity was detected in fractions: greater than 70 kD, 22-30 kD and 5.5-8 kD.