Photometrische Bestimmung von Thorium mit Indooxin

Zusammenfassung Es wird eine empfindliche Methode zur photometrischen Bestimmung von Thorium mit Indooxin bei Abwesenheit von Fremdionen mit Ausnahme der Alkali- und Erdalkaliionen beschrieben, die die Bestimmung von 0,1–6 g Th im Milliliter gestattet.Diese Arbeit wurde durch das Entgegenkommen von Herrn Prof. Dr. F. Hecht ermöglicht, dem wir hiermit unseren Dank aussprechen wollen.     

Prolongement d'un courant positif plurisousharmonique

The purpose of this Note is to prove an extension result for a positive plurisubharmonic (Psh) current T defined in the complement of a closed complete pluripolar set A, under the hypothesis that $H_{2p}(\overline{\mathrm{supp}T}\cap A)=0$ and that $d{d}^{c}T$ has a locally finite mass. We prove in the first part an Oka type inequality for a positive Psh current. We then prove an extension result for such a current across an irreductible analytic set, thereby generalizing a result of Siu concerning positive closed current and one of our previous results for a negative Psh current. To cite this article: K. Dabbek, C. R. Acad. Sci. Paris, Ser. I 342 (2006).     

Effect of IR laser radiation on the structure and optical properties of PC-PBT/Pd polymer nanocomposite films

ABSTRACT

Bayfol (PC-PBT blend ?lm) is a class of polymeric solid-state nuclear track detector which has a lot of applications in several radiation detection ?elds. It is a bisphenol-A polycarbonate PC blended with polybutylene terephthalate PBT. Bayfol/Palladium (PC-PBT/Pd) nanocomposite films have been deposited using the molding technique. It is worth mentioning that this report is almost the first one dealing with the topic of the changes of physical properties of Bayfol/Pd nanocomposite due to laser exposure. Samples from PC-PBT/Pd (5?wt%) nanocomposite were exposed to IR-pulsed laser of 5-W power, capable of producing 2000 pulses per second with pulse duration of 200?ns at 904?nm. The laser fluences were in the range 2–25?J/cm². The resultant modi?cations in the exposed nanocomposite samples have been studied as a function of fluence using different characterization techniques such as X-ray diffraction (XRD), UV spectroscopy and color difference studies. The results indicate the proper dispersion of Pd nanoparticles in the PC-PBT matrix that causes a strong intermolecular interaction between Pd and PC-PBT, resulted in an increase in refractive index and the amorphous phase. Also, it is found that the laser exposure reduces the optical energy gap that could be attributed to the increase in structural disorder of the exposed PC-PBT/Pd nanocomposites due to crosslinking. Further, the color intensity ΔE, which is the color difference between the exposed samples and the non-exposed one, was increased with increasing the laser fluence, convoyed by a significant increase in the green and yellow color components.     

Structural and Mössbauer studies of nanocrystalline Mn<Superscript>4+</Superscript>-doped Li<Subscript>0.5</Subscript>Fe<Subscript>2.5</Subscript>O<Subscript>4</Subscript> particles prepared by mechanical milling

The structure and magnetic properties of spinel-related Mn⁴⁺-doped Li_0.5Fe_2.5O₄ nanocrystalline particles of the composition Li_0.5Fe_2.25Mn_0.1875O₄, prepared by milling a pristine sample for different times, were investigated. The average crystallite and particle size, respectively, decreased form ～40 nm to ～10 nm and ～2.5 μm to ～10 nm with increasing milling time from 0 h to 70 h. Rietveld refinement of the XRD data of the non-milled sample show the Mn⁴⁺ dopant ions to substitute for Fe³⁺ at the octahedral B-sites of the spinel-related structure. The Mössbauer spectra of the milled ferrites indicate that more particles turn superparamagnetic with increasing milling time. The Mössbauer data collected at 78 K suggest that while in the non-milled sample the Mn⁴⁺ ions substitute for Fe³⁺ at the octahedral B-sites, this is reversed as milling proceeds with doped Mn⁴⁺ ions, balancing Fe³⁺ vacancies and possibly Li⁺ ions progressively migrate to the tetrahedral A-sites. This is supported by the slight increase observed in the magnetization of the milled samples relative to that of the non-milled one. The magnetic data suggest that in addition to the increasing superparamagentic component of the milled particles, thermal spin reversal and/or spin canting effects are possible at the surface layers of the nanoparticles.     

Nonradial large solutions of sublinear elliptic problems

Let p be a nonnegative locally bounded function on , N3, and 0<γ<1. Assuming that the oscillation sup_|x|=rp(x)−inf_|x|=rp(x) tends to zero as r→∞ at a specified rate, it is shown that the equation Δu=p(x)u^γ admits a positive solution in satisfying lim_|x|→∞u(x)=∞ if and only if

     

昆虫信息素研究III: 拟蚜虫警戒素的研究

合成了一系列碳数为十五和十四的倍半萜类蚜虫警戒素,并进行了生物活性测定,从中筛选有效化合物.     

Evaluation of the Antimicrobial Effect of Thymoquinone against Different Dental Pathogens: An In Vitro Study

This study aimed to evaluate the antimicrobial effect of Thymoquinone (TQ) on four different oral microorganisms. Minimum Bactericidal Concentration (MBC), Minimum Inhibition Concentration (MIC), Broth microdilution, and Well diffusion tests were used to determine the optimum antimicrobial concentrations of TQ against Streptococcus salivarius, Streptococcus oralis, Streptococcus mutans, and Staphylococcus aureus over 1, 3, 6, 12 and 24 h. Chlorhexidine 0.12% was selected as a positive control. The inhibitory effect of TQ on bacterial growth was most noticeable with S. salivarius, while the least affected was S. aureus. TQ’s MBC and MIC for S. oralis and S. aureus were comparable 2 mg/mL and 3 mg/mL, respectively. S. salivarius was most resistant to TQ and displayed a value of 5 mg/mL and 4 mg/mL for MIC and MBC, respectively. The viable count of different strains after exposure to TQ’s MBC values was most noticeable with S. aureus followed by S. oralis and S. mutans, while S. salivarius was least affected. This study emphasized the promising antimicrobial effect of TQ against the four main oral microorganisms. It has a potential preventive effect against dental caries as well as other oral diseases.