Pyrano[2,3-d]thiazoline-7-spiro-3
-(1
-substitutedindoline-2
-ones) 5a,b has been
synthesized and reacted with some nucleophile reagents to afford new
spirothiazolino[4,5:2
,3
]pyrano[6
,5
-d]pyrimidine derivatives 6a,b–13a,b, which
are analogues of some reported biologically active spiroheterocyclic compounds

Pyrano[2,3-d]thiazoline-7-spiro-3
-(1
-substitutedindoline-2
-ones) 5a,b has been
synthesized and reacted with some nucleophile reagents to afford new
spirothiazolino[4,5:2
,3
]pyrano[6
,5
-d]pyrimidine derivatives 6a,b–13a,b, which
are analogues of some reported biologically active spiroheterocyclic compounds

Pyrano[2,3-d]thiazoline-7-spiro-3
-(1
-substitutedindoline-2
-ones) 5a,b has been
synthesized and reacted with some nucleophile reagents to afford new
spirothiazolino[4,5:2
,3
]pyrano[6
,5
-d]pyrimidine derivatives 6a,b–13a,b, which
are analogues of some reported biologically active spiroheterocyclic compounds

Azotobacter chroococcum was grown on cultures containing five carbon sources alone and also in co-cultures with
three cellulolytic fungi (Aspergillus niger, Penicillium funiculosum and Trichoderma harzianum). In the absence of fungal
species, nitrogenase activity was relatively low. The best nitrogenase activity was recorded in cultures containing faba bean
straw followed by that in cultures havingwheat straw, sugar cane leaves, carboxymethyl cellulose (CMC) or cellulose. In co-cultures
with fungi, Azotobacter showed substantial nitrogenase activity on all tested substrates. Azotobacter-Trichoderma association
showed thg highest nitrogenase activity.

The effect of N fertilizers on nodulation, nitrogenase, nitrate reductase activities and growth of two cultivars of
soybean, Clark and Crauford was evaluated in a field experiment. KNO3 or NH4C1 were applied 27 days after
planting at 0,16, 32, 64 and 128 kg N/ha. Nodulation and growth of both cultivars significantly increased when N
was applied at low levels whereas specific N2-ase activity (SNA) slightly and insignificantly increased. Cv Crauford
showed a greater positive response than cv. Clark. Higher rates of KNO3 and NH4C1 (128 kg N/ha) significantly
depressed nodulation and SNA but slightly decreased the plant dry matter. Cv. Crauford was more tolerant to N
fertilizers than cv. Clark. The decline in SNA was ascribed to increased nitrate reductase activity (NRA) and higher
accumulation of nitrites in nodule cytosol. NRA and nitrate contents in nodules of cv. Clark were greater than that in
cv. Crauford. Results showed that NH4 + is the preferred N source with occasional increases in nodule number and
weight. This study provides an evidence for the nodulation and growth variability of soybean cultivars fertilized
with different levels of N. The results also suggest that diminishing NRA could contribute to increased N2 fixation
and the interaction between NO3- assimilation and N2 fixation is strongly dependent on the plant cultivar.

The effects of application of combined nitrogen fertilizer (ammonium nitrate or urea) on root-hair infection and nodulation of four grain legumes were studied. Young roots of each legume were inoculated with their compatible rhizobia. The application of the two forms of combined N either at the early stages of plant growth and/or at the time of nodule formation depressed root-hair curling, infection and nodulation. Infection of hairs on the primary roots was more sensitive to the N fertilizer than hair infection of secondary roots in bothVicia faba andPisum sativum. The nodule number and total fresh mass of the four legumes were drastically affected by fertilizer application. The combined N added both at early and at later stages significantly reduced the nodulation ofV. faba, Phaseolus vulgaris andVigna sinensis. The inhibitory effect of urea on nodulation ofP. sativum was only observed when the fertilizer was applied at the late stages of plant growth. It is concluded that, although the nodulation of the four legumes was suppressed by combined N, the initial events ofRhizobium-legume symbiosis (infection of roots and nodule initiation) are more sensitive to combined N than the stages after nodule formation

ABffI~CT. Six Bradyrhizobium (lupin) strains were evaluated for their ability to produce siderophores using four chemical
assays. Two strains gave positive reactions with chrome azurol S assay (CAS) and produced hydroxamate-type siderophores.
The other four strains gave negative results for siderophore production using the four assays. Generation time, growth yield
and hydroxamate production of one strain (WPBS 3201 D) were affected by the iron concentration of the culture medium and
the previous culture history of the cells. Resuspension of washed ceils grown previously in media supplemented with 0 and
20 IJmol/L Fe into differing iron regimes (0, 0_5, 1, 2, 4, 8, 10, 15 and 20 lamol/L Fe) suggest that the extent of hydroxamate
production depended on the growth history of the cells. Cells pregrown in 20 lamol/L Fe produced a high amount of hydroxamares
compared with cells pregrown in iron-free medium when resuspended in medium containing up to 4 Izmol/L Fe. Cells
pregrown in 20 lamol/L Fe were more sensitive to iron repression than those pregrown in 0.5 lamoi/L Fe. Mannitol was the best
carbon source for siderophore production. Siderophore synthesis was inhibited by 4-chloromercuribenzenesuifonie acid, 2,4-dinitrophenol,
sodium azide and MgCI 2 suggesting that an energized membrane and a mercapto group are essential and required
for hydroxamate synthesis in strain WPB5 3201 D

Bulk AsxGe40-xSe60 (with x = 0; 10 and 20 at.%) glasses were repared using the melt-quench technique. Short range order (SRO) was examined by X-ray diffraction using CuðKaÞ radiation in the wave vector interval 0.28 < K < 6.5 (1/A).

For Ge40Se60 glass, the first sharp diffraction peak (FSDP) is located at K = 1(1/A) and shifted to higher K-values with increasing As content.Consequently, the coherence length has a maximum value for the binary glass.The SRO parameters have been obtained from the total distribution function, TðrÞ: The inter-atomic distances obtained from the first and second peak are, r1 = 2.37 (A) and r2 = 3.93 (A) in good agreement with previous works.The fundamental structural unit of the studied glasses is the Ge-Se4/2 tetrahedral.

Bulk AsxGe40-xSe60 (with x = 0; 10 and 20 at.%) glasses were repared using the melt-quench technique. Short range order (SRO) was examined by X-ray diffraction using CuðKaÞ radiation in the wave vector interval 0.28 < K < 6.5 (1/A).

For Ge40Se60 glass, the first sharp diffraction peak (FSDP) is located at K = 1(1/A) and shifted to higher K-values with increasing As content.Consequently, the coherence length has a maximum value for the binary glass.The SRO parameters have been obtained from the total distribution function, TðrÞ: The inter-atomic distances obtained from the first and second peak are, r1 = 2.37 (A) and r2 = 3.93 (A) in good agreement with previous works.The fundamental structural unit of the studied glasses is the Ge-Se4/2 tetrahedral.