Dynamic SIMS analysis of cryo-prepared biological and geological specimens

The modification of a dynamic magnetic sector secondary ion mass spectrometry (SIMS) instrument to permit the analysis of frozen biological and geological samples is described. The SIMS instrument used for this study combines SIMS analysis with the generation of ion-induced secondary electron images, allowing direct superposition of the SIMS image onto the image of cellular structures. Secondary ion maps have been acquired with sub-micron resolution, permitting the characterisation of sub-cellular elemental distributions in plant cells and human fibroblast cells, as well as the distribution of chemical impurities at grain boundaries in polar ice samples. This cryo-preparation technique clearly extends the applicability of SIMS analysis to a wide range of samples.     

Luminescent metal complexes. 4—13C NMR spectra of the tris chelates of substituted 2,2′-bipyridyls and 1,10-phenanthrolines with ruthenium(II) and osmium(II)

¹³C Chemical shifts are reported for the ruthenium(II) tris complexes of thirteen 2,2′-bipyridyls and three 1,10-phenanthrolines and for the osmium(II) tris complexes of five 2,2′-bipyridyls. Chelation induced shifts (δ_complex – δ_ligand) are discussed in terms of models for π back-bonding. ¹³C NMR is shown to be a convenient tool for the direct observation of the geometrical isomerism of complexes formed from monosubstituted ligands.     

Independent oscillator model of a heat bath: Exact diagonalization of the Hamiltonian

The problem of a quantum oscillator coupled to an independent-oscillator model of a heat bath is discussed. The transformation to normal coordinates is explicitly constructed using the method of Ullersma. With this transformation an alternative derivation of an exact formula for the oscillator free energy is constructed. The various contributions to the oscillator energy are calculated, with the aim of further understanding this formula. Finally, the limitations of linear coupling models, such as that used by Ullersma, are discussed in the form of some critical remarks.     

Polysilicon TFT circuit design and performance

Both n- and p-channel polysilicon TFTs can be fabricated, allowing CMOS circuit techniques to be used. However, TFT characteristics are poor in comparison to conventional single-crystal MOSFETs, and relatively coarse design rules must be used to be compatible with processing on large-area glass plates. The authors examine these issues and describe the performance of a range of digital and analog circuit elements built using polysilicon TFTs. Digital circuit speeds in excess of 20 MHz are reported, along with operational amplifiers with over 80 dB of gain and more than 1-MHz unity-gain frequency. Several polysilicon TFT switched-capacitor circuits are also reported and shown to have adequate linearity, output swing, and settling time to form integrated data line drivers on an active-matrix liquid crystal display     

Surfactin-like structures of five cyclic depsipeptides from the marine isolate ofBacillus pumilus

Five cyclic depsipeptides with molecular masses of 1007, 1021, 1021, 1035, and 1035 were obtained fromBacillus pumilus KMM 150 associated with Australian marine spongeIrcinia sp. Their structures were assigned by mass spectrometric techniques (high-resolution fast atom bombardment and electron impact mass spectrometry), chemical modification, and extensive spectroscopic analysis, including several types of two-dimensional NMR.Deceased.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 979–983, May, 1995.The authors are grateful to Dr. V. V. Mikhailov, the Head of the Laboratory of marine microbiology of PIBC of the Far-Eastern Branch of the RAS, and to Dr. E. P. Ivanova for isolation, systematic determination, and cultivation of the strain KMM 150. The authors are also thankful to T. I. Zykova for carrying out the fermentative hydrolysis of peptide4c.     

Fabrication, RE performance, and yield of a combined limitingamplifier and dual-modulus prescalar GaAs IC chip

Production technology details, RF performance, and yield results for an ECL-compatible, L-band, limiting dual-modulus (÷10/11) prescalar are presented. Monolithic integration of analog and digital circuit functions is achieved using refractory self-aligned-gate FET technology. When tested with -22-dBm input signal power, one lot of six wafers had a total RF chip yield of 19% with a best-wafer yield of 43%. The average operating frequency was 1.45 GHz (SD=51 MHz) with an average power dissipation of 696 mW (SD=23 mW)