Photodegradation kinetics of some indolecarboxylic acids and their regulation effects on plant growth (groundnut and haricot bean)

Indolecarboxylic acids belong to the auxins group. They constitute a class of phytohormones, which play an important role in plant growth. This paper deals with the kinetics of six indolecarboxylic acids and their regulation effects on the growth of groundnut (Arachis hypogea) and haricot bean (Phaseolus vulgaris). The results obtained enabled us to establish a relationship between photodegradation rate constants and their regulation properties on the growth of these two plants. The paper shows that the compounds yielding the highest photodegradation rates were efficient growth regulators. In this regard, a few explanations are provided.     

On the Binary Codes of Steiner Triple Systems

The binary code spanned by the rows of the point byblock incidence matrix of a Steiner triple system STS(v)is studied. A sufficient condition for such a code to containa unique equivalence class of STS(v)'s of maximalrank within the code is proved. The code of the classical Steinertriple system defined by the lines in PG(n-1,2)(n3), or AG(n,3) (n3) is shown to contain exactly v codewordsof weight r=(v-1)/2, hence the system is characterizedby its code. In addition, the code of the projective STS(2ⁿ-1)is characterized as the unique (up to equivalence) binary linearcode with the given parameters and weight distribution. In general,the number of STS(v)'s contained in the code dependson the geometry of the codewords of weight r. Itis demonstrated that the ovals and hyperovals of the definingSTS(v) play a crucial role in this geometry. Thisrelation is utilized for the construction of some infinite classesof Steiner triple systems without ovals.     

Demonstration of phase correlation in multiwavelength mode-locked semiconductor diode lasers

Wideband spectral phase correlation is demonstrated from a multiwavelength mode-locked semiconductor laser. By use of frequency-resolved optical gating techniques, significant phase correlation was observed between multiple intracavity oscillating wavelengths, with wavelength separations of ~1 nm . The resultant temporal characteristics show a substantial modulation owing to the spectral coupling induced by intracavity-generated four-wave mixing. This result may lead to novel methods for directly generating ultrafast subpicosecond optical pulse sequences with spectrally tailored amplitude and phase characteristics from actively mode-locked semiconductor lasers.     

Realization of aligned three-dimensional single-crystal chromium nanostructures by thermal evaporation

Aligned three-dimensional single-crystal chromium nanostructures are fabricated onto a silicon substrate by thermal evaporation in a conventional thermal evaporator, where the incident angle of Cr vapor flux with respect to the substrate surface normal is fixed at 88°. The effects of the deposition time and incident angle on the morphology of the resulting nanostructures are investigated. The achieved Cr nanostructures are characterized by scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, and surface area measurement. This study provides a convenient way to fabricate three-dimensional single-crystal Cr nanostructures, which is suitable for batch fabrication and mass production. Finally, the same technique is employed to fabricate the nanostructures of other metals such as Ag, Au, Pd, and Ni.     

A Convenient Synthesis of N-Arylanthranilic Acids Using Ultrasonics in the Ullmann-Goldberg Condensation

Ultrasonics efficiently promotes the Ullmann-Goldberg condensation of 2-halogenobenzoic acids and primary aromatic amines to obtain various N-arylanthranilic acids.     

Mass Spectrometry Study of Coumarins: Correlation Between Charges of Atoms and Fragmentation Processes

The mass spectrometry of a number of 6-substituted coumarins was studied in the context of correlating fragmentation pathways and electronic charges of atoms performed by AM₁ semiempirical method. The atomic charges of atoms are found to be good predictors of the fragmentation pathways.