Preparation and spectroscopic studies of Hydroxyapatite embedded in Poly(N-Vinylpyrrolidone) matrix

Pure HAp powder was prepared by precipitation and HAp/PVP composites were prepared by casting technique. X-ray diffraction was performed to examine the crystallinity and the complexation between HAp and PVP when the amount of HAp increased. XRD and EDX analysis showed that the concentration 15 wt% is the most confirmation for the formation of HAp. SEM shows more than one form of HAp such as plates, needles and bundles in the morphological structure of pure HAp and 15 wt% of HAp. Two main weight loss regions and two peaks were observed in TGA and DSC thermograms that reveal reduction in the thermal stability of the prepared samples as HAp content increases. The activation energy of the films was decreased with increasing the concentration of HAp. DSC thermographs of the samples show that the values of the glass transition temperatures are decreased with increasing the content of HAp filler which suggest that HAp filler act as plasticizer. The conductivity–temperature plots show linear variation, which suggests an Arrhenius behavior. The conductivity increases with adding HAp content for low concentrations while decreased for the critical concentration (15 wt %) which confirms the XRD results

You Don’t Have To Go Home But You Carrot Stay Here: Root-Knot Nematode Biological Control in Carrots

Root-knot nematodes cause tens of billions of dollars in damages annually in agricultural production. The enormous economic losses brought about by nematodes, combined with the downsides to current methods for handling them, have led to an increased focus in understanding natural plant defense mechanisms and finding alternative methods to lessen the damage done by root-knot nematodes. Endophyte biocontrol agents such as Trichoderma harzianum have shown promise in reducing nematode damage. Recent studies have demonstrated that soil management practices and plant genotype can influence endophyte community structure, but it is unclear whether such differences influence susceptibility to nematode damage. This study seeks to better understand these dynamics by quantifying how differences in endophyte community structure influence nematode (Meloidgyne incognita) infection and plant performance in three carrot varieties that are susceptible, moderately resistant, or highly resistant to nematodes. The treatments are 1) unamended control, 2) Trichoderma harzianum, 3) endophytes from an organically farmed field, and 4) endophytes from a conventionally farmed field. Preliminary results indicate that carrot genotype significantly impacts carrot biomass, and carrots grown in the presence of endophytes from organically farmed soils have greater biomass than carrots grown in the other treatments. Analysis of endophyte community structure and nematode infection are ongoing

Synthesis and Molluscicidal Activity of Some Newly Substituted Chromene and Pyrano[2,3-c]pyrazole Derivatives

The arylidene derivatives 3a-f react with 1,3-cyclohexanedioneand dimedone 4a,b to afford the 4-(2- or 3-pyridyl) or 4-pipronyl-chromene derivatives 6a-l. The arylidene derivatives 3a-c react with the pyrazolone derivatives 7a,b to afford the pyrano[2,3-c]pyrazole derivatives 9af.The molluscicidal activity of the synthesized compounds towards Biomphalaria alexandrina snails, the intermediate host of Schistosoma mansoni, was investigated and most of them showed weak to moderate activity.

Heterocyclic synthesis with ω-bromoacetophenone: Synthesis of some new pyrazole, pyridazine and furan derivatives

p-Bromophenacylnitrile derivatives 3a,b react with hydrazinederivatives under different conditions to afford the diaminopyrazoles 4a,b, the pyridazine-6-imines 5a,b,and 5-aminopyrazoles 11a,b. Refluxing of 5a in ethanol/hydrochloric acid mixture furnished its transformation into the pyridazine-6-one 6 while 5b under the same reaction conditions, underwent ring contraction expelling phenyl hydrazine to afford the furan derivative 7.Compound 7 could also be obtained from 3a upon refluxin ethanol catalyzed by triethylamine. Ethyl  phenacylcyanoacetate 3b reacts with hydrazine hydrate and phenylhydrazine to afford the 4-phenacylpyrazole derivatives11a,b respectively. Compound 3b afforded a mixture ofthe two furan derivatives 12 and 13 upon reflux in ethanolcatalyzed by triethylamine. Compound 3b also undergoesthe coupling reaction with the aromatic diazoniumsalts 14a-d to afford the pyrazole derivatives 16a-d presumablyvia the hydrazo derivatives 15a-d respectively

Multiple exciton generation in nano-crystals revisited: Consistent calculation of the yield based on pump-probe spectroscopy

Multiple exciton generation (MEG) is a process in which more than one exciton is generated upon the absorption of a high energy photon, typically higher than two times the band gap, in semiconductor nanocrystals. It can be observed experimentally using time resolved spectroscopy such as the transient absorption measurements. Quantification of the MEG yield is usu- ally done by assuming that the bi-exciton signal is twice the signal from a single exciton. Herein we show that this assumption is not always justified and may lead to significant errors in the estimated MEG yields. We develop a methodology to determine proper scaling factors to the signals from the transient absorption experiments. Using the methodology we find modest MEG yields in lead chalcogenide nanocrystals including the nanorods