Effect of flame weed control on various weed species at various developmental stages

ArticlePhysical methods of weed control as solarization, mulching, use of electricity, steam and flame are now an alternative in the organically grown crop. Flame weeder already has a wide range of practical use , particularly in the cultivation of vegetables in alternative form without any chemical treatment. Compared to chemical spraying, the use of flame weeder is more expensive, but we can compensate the costs by the added value of bioproducts. The issue of costs affects the wider use of the method in practice, but it may be offset by increased e fficiency of weed control. The correct parameters of flame weeder, such as burner angle, burner height, the gas pressure, speed of weeder as well as the growth stage of the weed, weed species, climate conditions etc., can increase the effectiveness of weed control. Field and laboratory tests carried out in Canada and Slovakia were aimed at verifying the influence of parameters on the effectiveness of flame weed control

The Development of Transport in the Czech Republic

Before 1989, transport in the former Czechoslovakia met its tasks based on the controlling principles of planned economy, focused eastwards and oriented on cooperation between the Eastern Bloc countries within COMECOM. Due to the preference for raw material extraction and heavy industry, the transport sector dealt mainly with transporting commodities of these branches with high demands in volume. The planned economic principles were also reflected by the consistent division of transport work with a preference for stack substrate transport by rail. The change of the political and economic circumstances in November 1989 influenced the life and needs of society substantially. A market economy has come, focused on the market of developed European countries and having an impact on the transport sector as such, individual transport systems, transport preferences and transported commodities [2]. As at 1 January 1993, Czechoslovakia has been divided into two independent countries, i.e. the Czech Republic and Slovakia. Therefore the following data from the Transport Statistics of the Czech Republic [1] are comparable starting from 1994. The authors of the article had data available until 2006

Quark Condensate in the Deuteron

We study the changes produced by the deuteron on the QCD quark condensate by means the Feynman-Hellmann theorem and find that the pion mass dependence of the pion-nucleon coupling could play an important role. We also discuss the relation between the many body effect of the condensate and the meson exchange currents, as seen by photons and pions. For pion probes, the many-body term in the physical amplitude differs significantly from that of soft pions, the one linked to the condensate. Thus no information about the many-body term of the condensate can be extracted from the pion-deuteron scattering length. On the other hand, in the Compton amplitude, the relationship with the condensate is a more direct one.Comment: to appear in Physics Review C (19 pages, 3 figures

Towards an understanding of isospin violation in pion-nucleon scattering

We investigate isospin breaking in low-energy pion-nucleon scattering in the framework of chiral perturbation theory. This work extends the systematic analysis of [1] to the energy range above threshold. Various relations, which identically vanish in the limit of isospin symmetry, are used to quantify isospin breaking effects. We study the energy dependence of the S- and P-wave projections of these ratios and find dramatic effects in the S-waves of those two relations which are given in terms of isoscalar quantities only. This effect drops rather quickly with growing center-of-mass energy.Comment: 12 pp, REVTeX, 8 figs, FZJ-IKP(TH)-2000-2

Preventive Effects of Flavonoids on Alloxan-Induced Diabetes Mellitus in Rats

The aim of the present study was the evaluation of possible protective effects of quercetin and chrysin in experimental alloxan-induced diabetes in rats. Alloxan was injected at a single dose of 60 mg/kg (into the tail vein) for diabetes induction. Quercetin (50 and 100 mg/kg; orally) and chrysin (50 and 100 mg/kg; orally) were administered daily for 3 days prior and 7 days after alloxan injection. Alloxan induced a significant increase of glycaemia (p p p p < 0.01). On the other hand, glycosuria was increased in all groups of animals receiving alloxan. We suggest that the protective effect of the used flavonoids in experimental diabetes mellitus may be related to their antioxidative/chelatory properties. Increased glycosuria indicated that inhibition of renal glucose reabsorption may also play a role in the hypoglycaemic effect of both flavonoids

Mechanochemical Synthesis and Characterization of II-VI Nanocrystals: Challenge for Cytotoxicity Issues

CdSe@ZnS nanocrystals have been prepared by a two-step solid state mechanochemical synthesis. CdSe prepared from elements in the first step is mixed with ZnS synthesized from zinc acetate and sodium sulfide in the second step. The crystallite size of the new type CdSe@ZnS nanocrystals determined by X-ray diffraction Rietveld refined method was 35 nm and 10 nm for CdSe and ZnS, respectively. Energy dispersive/transmission electron microscopy/energy dispersive spectroscopy methods show good crystallinity of the nanoparticles and scanning electron microscopy elemental mapping illustrate consistent distribution of Cd, Se, Zn and S elements in the bulk of samples. UV-VIS spectra show an onset at 320 nm with calculated bandgap 3.85 eV. This absorption arises from the vibration modes of Zn-S bonds. The nanocrystals show the blue shift from the bandgap of bulk ZnS (3.66 eV). The synthesized CdSe@ZnS nanocrystals have been tested for dissolution, cytotoxicity and L-cysteine conjugation. The dissolution of Cd was less than 0.05 μg $mL^{-1}$ (in comparison with 0.8 μg $mL^{-1}$ which was evidenced for CdSe alone). The very low cytotoxic activity for selected cancer cell lines has been evidenced. CdSe@ZnS nanocrystals coated with L-cysteine are water-soluble and have a great potential in biomedical engineering as fluorescent labels