Crystal and molecular structure oftrans-dichlorobis(oxazole)palladium(II)

The crystal and molecular structure oftrans-dichlorobis(oxazole)palladium-(II), Pd(C₃H₃ON)₂Cl₂, has been determined by single-crystal X-ray diffraction techniques using counter methods and has been refined by full-matrix least-squares procedures to a finalR index of 0.022. The complex crystallizes in the triclinic space groupP¯1 with unit cell dimensions ofa = 6.957(1),b = 7.506(1),c = 5.538(1) Å, = 109.22(1), = 91.37(1), and = 115.09(1) °, withZ = 1. The palladium(II) ion, located at an inversion center, is coordinated in a regular square-planar manner to two chloride ions at 2.293(1) Å and, at 2.016(2) Å, to the nitrogen atoms of two oxazole ligands. The planar oxazole rings are tilted 33 ° with respect to the PdN₂Cl₂ plane. Further verification of the presence of oxazole in the complex was obtained by high-resolution mass spectrometry. Crystals of Pd(C₃H₃ON)₂Cl₂ resulted irreproducibly from attempts to prepare single crystals of a previously reported dimeric palladium(II) disulfide complex by treating Pd(CH₃CN)₂Cl₂ with a slight excess of diphenyl disulfide in benzene in the atmosphere. The source of the oxazole is not understood.     

An ion grouping method for calculating the Madelung constant for the sodium chloride lattice

A method has been developed for calculating the Madelung constant for a sodium chloride lattice. In this method, a reference ion is selected and all other ions are placed in groups around the reference ion. To include ions in all locations, seven types of groups are necessary. Recursion formulas are obtained to compute the effect of each group of ions and the Madelung constant is computed from the total effect produced by all the groups. A total of 29 cubical shells of ions around the reference ion were used in the calculation. The computation produces an oscillating function which alternately goes above and below the actual Madelung constant as the computation is expanded to include each successive shell of ions. A numerical method is described to obtain the average value of the oscillating function. A value of the Madelung constant of 1.74759 results from the abbreviated calculation.     

The influence of temporal cues on the strength of periodicity pitches

Three different waveforms were generated from the same component frequencies by setting the phase of the components so they were either homophasic (all component sinusoids start at 0 degree), diphasic (sinusoids alternate between -45 degrees and + 45 degrees), or heterophasic (starting phase randomly selected). Listeners were asked to rate the saliency of all periodicity pitches they could detect in stimuli which contained 12 or more components at frequencies above the region where pitches were perceived . A major finding was that the highest ratings of fundamental frequency (f1) pitch "strength" were always obtained for homophasic waveforms, which among the test stimuli have the most abrupt envelope fluctuations. In contrast, diphasic and heterophasic waveforms, which have smoother envelopes, yielded lower pitch strength estimates at f1 and higher ratings two octaves above the fundamental. These data indicate that information concerning the stimulus waveform envelope influences the relative prominence of competing pitches evoked by periodicity pitch stimuli. However, no one-to-one correspondence between pitch and waveform periodicity is apparent.     

In silico targeting PAD4 for the treatment of rheumatoid arthritis

Structural Chemistry - Rheumatoid arthritis (RA) is an autoimmune disorder that causes chronic inflammation with periodic bursts of activity in multiple synovial joints which lead to irreversible...     

Nuclear orbiting and anomalies in nuclear reactions

In this paper, we report our measurements of back-angle oxygen and carbon particle yields from ¹⁶O+⁸⁹Y, ¹²C+⁹³Nb reactions forming the same compound nucleus ¹⁰⁵Ag at the same excitation energy and spin distribution. We find anomalously large oxygen yield and entrance channel dependence at high excitation energies from ¹⁶O+⁸⁹Y reaction implying formation of a dinuclear orbiting complex. Possible connection between nuclear orbiting and fast fission is also discussed.